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Materials for energy and environment


Advanced functional materials for environmental monitoring and applications

About three quarters of the European population lives in urban areas. The urban environment has a profound effect on people’s health and well-being. Environmental sustainability of the urban society is a key issue in the era of smart cities and information services for the quality of life. Solid state sensors based on functional materials have been developed for several decades and recent improvements in nanotechnology and multifunctional materials have open up the possibility to develop a new generation of sensitive, selective and stable sensors, with largely improved capacity to give relevant information both on a personal level and system levels.




Air quality takes a prominent position in discussions on urban environment and health, and it is a concern for many inhabitants of urban areas. Nanotechnologies including nanostructured materials for sensing, chemical sensors, portable systems and commercial devices give a challenging opportunity to create a new generation of nanosensors for air quality control. Functional nanomaterials (i.e., nanowires, nanotubes, graphene, nanoparticles of metal-oxides, carbonnanostructures, large band-gap semiconductors, and metals) with new sensing properties (detection at ppb-level, high sensitivity and selectivity), self-heating and durable operations for low powered (tens of mWatt to tens of mWatt) devices are potential key elements in advanced air quality measurements for indoor and outdoor air quality monitoring.


Modeling provides a tool for nanomaterials tailor-made for specific purposes and applications. In order to realize functional, sensor-systems improvements in packaging, testing and aging are also very important and a focus area of this conference as current research hot-issues.


Nanotechnologies offer a big challenge to create innovative low-cost nanosensors for air quality monitoring. Functional nanomaterials (one- and two-dimensional nanostructures of carbon, graphene, metal-oxides, metals, polymers, supramolecular materials, self-organized materials, organic/inorganic materials, hybrid composites) with new tailored properties are key-issues for the development of low-powered devices for indoor and outdoor air quality monitoring, including practical applications such as geo-tagged database collected by networked stationary or mobile smart devices to address new sensing concepts for novel air quality monitoring and mapping techniques of gas molecules and particulate matter. These solid-state chemical sensors based on smart materials are useful for real deployment and complementary to the existing official high-cost high-quality air-quality monitoring stations used by public authorities, scientists or community groups.


Many worldwide investigators are involved in research in materials physics/chemistry and engineering, including nanosciences and nanotechnologies for sensing applications. Current international research includes the design and synthesis of organic, inorganic, polymers, and hybrid materials, the development of biomimetic materials and biomaterials, the discovery of new organometallic catalysts, the synthesis of nano- and mesoscopic materials including raw materials, the preparation of multilayers and multifunctional coatings, the study of chemistry of surfaces and interfaces, the exploration of the sensing properties of reactive materials, the characterization of the matter at nanoscale level for deep insights, the photo-physical study of supramolecular materials and the demonstration of functional nano/micro systems.


Basic research on sensing mechanisms and gas/surface interaction is critical for advancements in materials science and nanosensors in order to address practical applications in the field of the environmental monitoring, safety, security, healthcare, automation, green buildings, energy efficiency, transportations, food quality, industrial process control.


Hot topics to be covered by the symposium:


The specific technological areas are:


  • Advanced gas sensing semiconducting materials
  • Hybrid materials and nanocomposites for gas sensing
  • Catalytic sensing materials
  • Device fabrication, packaging, testing and aging
  • New (nano)sensors for monitoring gaseous and liquid pollutants
  • Ab initio modeling of gas/surface interaction
  • Surface-sensitive spectroscopies for studying sensor/gas interaction
  • Modeling of materials, devices and sensor systems
  • Functional applications




Proceedings as Regular Research Papers will be managed by a peer-review process in a Special Issue to be published in Journal of Sensors and Sensor Systems (JSSS) edited by Copernicus Publications.


Deadline for submission to Special Issue JSSS: 30 June 2014
Publication of Special Issue JSSS expected on December 2014


Manuscripts must be submitted on‐line via the JSSS Manuscript Submission, see:


For manuscript preparation and submission, please follow the guidelines and template in the Information for Authors at the JSSS Journal webpage:


Further information on Special Issue JSSS: Dr. Michele Penza, ENEA, Brindisi, Italy:







Symposium organizers:


Michele Penza
ENEA Italian National Agency for New Sensing Technologies
Energy and Sustainable Economic Development
PO BOX 51 Br-4
I-72100 Brindisi
Phone: +39 0831 201422
Fax: +39 0831 201423


Anita Lloyd Spetz
Linköping University/Oulu University
Dept. Physics, Chemistry and Biology
Linköping University
SE-581 83 Linköping
Phone: +46 13 281710; (Finland): +358 294 482717
Fax: +46 13 137568


Albert Romano-Rodriguez
University of Barcelona
Departament d’Electrònica
Martí i Franquès 1
08028 Barcelona
Phone: +34 93 4039156
Fax: +34 93 4021148


Yongxiang Li
Shanghai Institute of Ceramics
Chinese Academy of Sciences
No.1295 Dingxi Road
Phone: +86 21 52411066
Fax: +86 21 52413122

Meyya Meyyappan
Ames Research Center
MS 229-3
Moffett Field, CA 94035
Phone: +1 650 604 2616

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08:45 Welcome Address    
Nanostructured Metal Oxides Chemical Sensors I : Anita Lloyd Spetz Linköping University (Sweden) and University of Oulu (Finland), Michele Penza, ENEA (Italy), Albert Romano-Rodriguez, Universitat de Barcelona (Spain)
Authors : Bilge Saruhan, Azhar A. Haidry, Yakup Gönüllü
Affiliations : German Aerospace Center, German Aerospace Center, University of Cologne

Resume : High-temperature combustion in engines of vehicles and airplanes, energy production turbines, power plants and at industrial processes is the main reason for the release of pollutants. For monitoring of these processes and for control of emission, the use and development of high stability, selectivity and sensitivity sensors are required. NOx is one of the important green-house emission gases, produced during combustion processes and cannot be avoided by solely improving the fuel-quality. Gas sensors are extensively used for the precise determination of the quantity and chemistry of gas emissions. In-situ monitoring and real-time detection of emission are essential for the control of combustion processes. This report presents the recent developments achieved in our group at DLR related to transient oxide layers as gas sensor electrodes (nanostructured doped/undoped TiO2- and SnO2-sensing layers) employed for detection of NO2 at temperatures above 400°C. The sensor devices are based on a simple design and manufactured by sputtering technique as well as anodic oxidation process. Nanotubular structuring as well as doping of TiO2 with Al and Cr yields favorable properties regarding sensor’s selectivity and sensitivity. Use of sensor arrays and integration of sensing layers into the compounds allows the measurement of a broader range of gas concentrations at a wider temperature range up to 900°C in atmospheres containing humidity and reducing gases such as CO.

Authors : Joni Huotari (1), Wei Cao (2), Robert Bjorklund (3), Yuran Niu (4), Vladimir Pankratov (2), Jyrki Lappalainen (1), Anita Lloyd Spetz (1,3), Marko Huttula (2)
Affiliations : (1) Microelectronics and Materials Physics Laboratories, University of Oulu, P.O. Box 4500, FIN-90014 Oulu, Finland; (2) Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland; (3) Department of Physics, Chemistry and Biology, Linköping University, SE-581 83, Linköping, Sweden; (4) MAX-lab, Lund University, SE-221 00 Lund, Sweden

Resume : Detailed structural characterization of solid state vanadium oxide phases of V2O5 and V7O16, and their mixtures was performed. Vanadium oxide thin films were manufactured by pulsed laser deposition on oxidized silicon substrates. The grazing incidence X-ray diffraction together with Rietveld refinement showed the films were composed of V2O5 phase, but also of another vanadium oxide phase, identified as V7O16, usually seen only in the wall structure of vanadium oxide nanotubes (VOx-NT’s). Raman spectroscopy studies strongly supported these findings. X-ray photoelectron spectroscopy studies showed that the valence structure of the thin films varied according to phase structure. When the films were composed solely of V2O5 phase, the presence of V5+ ions was pronounced and when the amount of V7O16 phase increased in films, the amount V4+ ions increased as well. The near-edge X-ray absorption fine structure (NEXAFS) studies from vanadium L-edge and oxygen K-edge, supported the XPS studies strongly. The vanadium L-edge spectra of the films showed also that the amount of V4+ ions increased when the presence of V7O16 phase got stronger in the thin films. Vanadium oxide thin films with similar phase compositions were tested as a sensing material for ammonia gas and were found to be highly sensitive to NH3, down to ppb-level. Also, the thin film sensors were able to detect ammonia even in the presence of NO gas in the same atmosphere.

Authors : A. Goldoni #, L. D'Arsiè ^, G. Di Santo #, M. Caputo #, L. Sangaletti *, V. Alijani #
Affiliations : # Elettra - Sincrotrone Trieste, Trieste, Italy ^ Queens’ College, Cambridge, UK * Università Cattolica del Sacro Cuore, Brescia, Italy

Resume : Nanopillars of SnO2 grown starting from ITO on glass by means of chemical vapor deposition in acetylene atmosphere, reveal as extremely sensitive gas sensors. Measurements in air and in vacuum conditions of hydrogen, ethylene, oxygen, NO2, Ammonia and CO2 shows for some gases a sensitivity in the PPT range and a very fast recovery time compared with commercial sensors. Covering the nano pillars with ZnO or carbon will change the sensitivity or completely attenuate the sensor response.

10:00 Coffee Break    
Nanostructured Metal Oxides Chemical Sensors II : Jyrki Lappalainen, University of Oulu (Finland) and Gemma Garcia-Mandayo, CEIT (Spain)
Authors : F.E. Annanouch, J.L. Ramírez, M. Camara*, D. Briand* and E. Llobet
Affiliations : MINOS-EMaS, Universitat Rovira i Virgili, Tarragona, Spain *EPFL, Samlab, Neuchatel, Switzerland

Resume : Aerosol assisted CVD, as shown by our prior results [1], is a flexible, inexpensive and high-yield technique for growing metal oxides with remarkable gas sensing properties. Here we show that this technique is suitable for growing metal-decorated low-dimensional metal oxides directly on flexible polymeric hotplates. This represents a significant breakthrough towards mass-market affordable nanotechnology-based gas sensors, taking into account integration easiness and a great reduction in production cost. Au or Pt nanoparticle decorated tungsten oxide nanowire (5 microns long and 60 to 120 nm wide) films were grown at 380ºC by AA-CVD directly on the electrode area of polymeric hotplates using tungsten hexacarbonyl, hydrogen tetrachloroaurate and hydrogen hexachloroplatinate as precursors. On the other hand, porous nanoparticle films of pure tungsten oxide were obtained under the same conditions. The response to hydrogen of the different sensors was tested at different operating temperatures (200 to 350ºC). The optimal operating temperature was found to be 300ºC. Pt-decorated tungsten oxide NWs (followed by Au-WO3 NWs) showed the highest response to hydrogen with over an order of magnitude decrease in resistance when exposed to 500 ppm of H2. Pure tungsten oxide NP films exhibited weak response to hydrogen. At the conference, morphological and compositional studies together with humidity effect will be presented and discussed in detail. [1] Adv. Funct. Mat. 23 (2013) 1313-1322.

Authors : C. Baratto*, Raj Kumar*, G. Faglia*, G. Sberveglieri*, K.Vojisavljevic**, B.Malic**
Affiliations : * CNR-INO SENSOR Lab. and University of Brescia, Dept. of Information Engineering, Via Valotti, 9 25133 Brescia, Italy ** Electronic Ceramics Department, Jozef Stefan Institute Jamova 39, SI-1000, Ljubljana, Slovenia

Resume : Recently, new ternary material with p-type behavior attracted significant research interest in the field of chemical gas sensing, since they can be teamed with well-known n-type materials to be use in a sensing matrix like an electronic nose. Copper aluminum oxide is a p-type ternary oxide that raised interest as a transparent conducting material in the delafossite phase CuAlO2; we demonstrated that different phases with higher resistance can be applied successfully as p-type resistive gas sensor for ozone detection. Copper aluminum oxide thin films were deposited by RF sputtering in inert atmosphere starting with a delafossite CuAlO2 target. Thin films with different morphology and phases were obtained by changing the deposition temperature and post annealing treatment: in some cases polycrystalline nanowires were observed on silicon substrate. Thin films were tested for ozone, NO2 and reducing gas (CO, ethanol, acetone) sensing in the working temperature range from 200-500°C. Two order of magnitude sensor response towards 70 ppb of ozone was observed at 300°C. Response to reducing gases was much smaller than that to ozone and optimum working temperature was observed at 400°C. Sensing capabilities will be discussed in relation to thin film morphology and phases analyzed by SEM, Raman spectroscopy and XRD. The research leading to these results has received funding from the European Communities 7th Framework Programme under the grant agreement NMP3-LA-2010-246334, ‘‘ORAMA’’.

Authors : Sadullah OZTURK1, Arif KOSEMEN2, Necmettin KILINC1, Zafer Ziya OZTURK1.3*
Affiliations : 1Gebze Institute of Technology, Department of Physics, Kocaeli 41400, Turkey 2Mus Alparslan University, Department of Physics, 49100 Mus, Turkey 3TUBITAK Marmara Research Center, Institute of Material Science, Kocaeli, Turkey

Resume : ZnO, is the member of semiconducting metal oxide materials, has wide and direct band gap and large exciton binding energy. ZnO are very good candidate as a gas sensing material. In gas sensor metal oxides are very sensitive to changing ambient surrounding of them at elevated temperatures (200?C-400?C). Selectivity of ZnO based gas sensors is so poor depending on showing same sensitivity. To overcome this problem, semiconducting metal oxide materials are functionalized with doping or heterostructures with catalytical materials. Palladium has catalytical effects on sensing of hydrogen. Palladium modified ZnO can sense hydrogen at low temperature especially room temperature. There have been some reports on enhancing sensing facilities of semiconducting metal oxide gas sensor under UV light. In this study, ZnO nanorods were fabricated on both ITO coated and uncoated glass substrate by hydrothermal process in 3h at 90?C. Hydrothermal process was realized in aqueous solution of Zn(NO3)2*6H2O and hexamethylenetetramine. Then metal electrodes were coated on ZnO nanorods by thermal evaporation in order to fabricate sensor device and the thickness was 100 nm. Fabricated sensor sample was tested to different gases depending on concentration and temperature. Moreover sensing measurements were realized in dark and UV illuminated ambient. Under UV illumination, the sensors showed high sensitivity, low response and recovery times. Acknowledgement: This study was supported by Scientific and Technological Research Council of Turkey (TUBİTAK) with Project Number: 111M261.

Authors : E. Xuriguera (1), O. Monereo (1), C. López-Gándara (2), N. Bonet (2), F. M. Ramos (2), A. Cirera (1)
Affiliations : (1) MIND-IN2UB, Electronics Department, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain; (2) FAE-Francisco Albero S.A.U., Rafael Barradas 19, 08908, L’Hospitalet de Llobregat, Spain

Resume : Up to now, the measurement of exhaust gases for combustion control (lambda sensors) is mainly dominated by YSZ electrochemical and TiO2 resistive devices. The use of these materials requires from high temperature. These devices are large to keep mechanical integrity at high temperature. Besides, the use of these devices is not adequate for all range lambda parameter. These drawbacks discourage these well known sensors for very reach combustion such hydrogen, in which temperature of the device should be the lowest possible. To avoid these problems, a fast, simple and reliable exhaust gas sensor based on SnO2 nanofibers has been developed by electrospinning on ceramic substrates with Pt interdigital electrodes. The spun nanofibers produced by this process, offer the advantage to produce thin mats with high surface area. The compatibility with microceramic technologies (LTCC, HTCC) results in a micro-device (3x3 mm). Our results indicateshigh repeatability and excellent response and sensibility lambda parameter that allows measurements from lambda that ranges from 0.3 up to 1.2. The response time is about 1-2 s at working temperature around 250ºC. The linear dependence of the response value on lambda factor observed for undoped SnO2 nanofibers in contraposition with non-linear dependence of doped ones suggest an interesting catalytic activity of the dopants. In conclusion, electrospinning method has been demonstrated like a simple method for the large-scale synthesis of SnO2 nanofibers and technological procedures and sensor results will be presented to show the reliability of the device.

Authors : T. Sauerwald 1; M. Afshar 2; Marius Rodner 1; E. Preiß 2; D. Feili 2; H. Seidel 2; A. Schütze 1
Affiliations : 1 Saarland University /Lab for Measurement Technology, Saarbrücken/GER; 2 Saarland University / Lab of Micromechanics, Microfluidics/Microactuators, Saarbrücken/GER

Resume : A new process for the preparation of nanowire metal oxide is presented to be used for the production of gas sensors with low power consumption and low cost. We demonstrate the processing of a four point probed indium-tin-oxide (ITO) single-nanowire and its suitability as NOx sensor for environmental monitoring. Nanowires were structured by laser enhanced lithography with lengths between 60-90 µm, widths of 450-650 nm and a thickness of 100 nm connected with four point gold-electrodes. The single nanowire is simultaneously used as sensor and heater filament. The sensor temperature can be estimated by correlating the heating power per area with resistance measurements obtain by temperature coefficient measurements with passive heating. We achieve a temperature of 120 °C with constant heating power of 3.8 mW for a wire with 90 µm length and 450 nm width on a glass substrate. The ITO wire shows n-type semiconducting behavior and exhibits good sensitivity and high selectivity towards nitrogen dioxide (NO2). A significant sensor response (relative change of resistance) was recorded after exposure to 0.1-50 ppm NO2 in humid air. The sensor showed no response vs. carbon monoxide (CO) up to 2000 ppm and only a small response against a variation of oxygen concentration O2 between 0-20 %. Moreover, the time constants for adsorption and desorption processes were studied in order to correlate the interaction between response times and sensor temperature.

Authors : C.Fabrega, J.R.Morante
Affiliations : IREC, Catalonian Institute for Energy Research, Jardíns de les Dones de Negre,1. San Adrià del Besòs. 08930. Spain

Resume : After more than 50 years, from the use of metal oxides for gas sensing technologies arise still many questions concerning to the understanding and control of the mechanisms taking place at its surface. Unlike the use of nanoparticles, metal oxide nanowires can facilitate a more robust scenario for advancing in the required answers in order to achieve low cost and high mass production reliable integrated gas sensors. In this contribution, an insight into chemical to electrical transduction mechanisms taking place at the surface of single metal oxide nanowire is reported. This analysis is performed considering the consequences on the main parameters for a resistive gas sensor from the found behavior in a nanowire taken as a metal oxide monocrystal at the nanoscale level. Surface chemical reaction kinetics is discussed considering competitiveness phenomena among different active sites and gas species. Experimental results for different representative casuistic of gas target species are shown to determine and understand sensor selectivity’s. Kinetic properties are proposed as a particular signature for each one of the possible surface chemical reactions allowing their identification and distinction. Likewise, features as thermal inertia limitation and effects of the molecular and monoatomic absorbed oxygen are also estimated considering operation working modes based on the nanowire self-heating. Furthermore, the applicability of a surface electrical field on one dimensional metal oxide nanostructure for enhancing the surface ionization of the absorbed molecules is suggested as a new type of metal oxide based nanosensor for achieving improved selectivity’s

12:30 Lunch    
Graphene Chemical Sensors I : Jérôme Brunet, Université Blaise Pascal and CNRS (France) and Jens Eriksson, Linköping University (Sweden)
Authors : Ruth Pearce 1, Anita Lloyd Spetz 2, Jens Eriksson 2 and Rositza Yakimova 2
Affiliations : 1) The National Physical Laboratory, U.K. 2) Linkoping University, Sweden

Resume : Graphene can be formed as a truly one dimensional material comprising a single atomic layer, however, it most often is produced along with some bi-layer or thicker areas of graphene. The effect of increasing layer number on the electronic properties of graphene has been the topic of much investigation but, as yet, the effect of layer thickness on the sensitivity of graphene gas sensors is little-studied. The effect of electron withdrawing and donating gases on the work function, carrier concentration and mobility of single and bi-layer graphene is discussed along with atomic force microscopy characterisation techniques which reveal the nanoscale functionality of a sensor surface. Single layer graphene has every atom on the surface, leading to electronic properties which are highly susceptible to doping from both the substrate and the environment. The linear band structure of graphene has a vanishing density of states at the Dirac point, with narrow bands above and below. If the Fermi level lies in this linear region, even a small change in carrier concentration leads to a large change in conductivity. Consequently, the conductivity of graphene can be dramatically altered by small concentrations of electron-withdrawing or donating gases. In contrast to single-layer graphene, the band structure of non-rotated bi-layer graphene is parabolic, with a broader density of states near the Dirac point, arguably making it a less sensitive sensor material. Atomic force microscopy (AFM) is a well-known technique for mapping nanoscale changes in the topography of sensor materials. Many other modes of operation can also be used to give information about the mechanism of response of a sensor device. For example, scanning Kelvin probe microscopy gives information about the uniformity of the work function of a surface. In graphene this enables the identification of areas of graphene of different thicknesses. Environmental scanning Kelvin probe microscopy, where the work function of the surface is mapped in controlled environments, is a useful tool for visualisation of the relative changes in work function over sensor devices. The effect of changing environment on each component of the device can be measured giving insight into the mechanism of sensor response at the nanoscale. Examples of such effects include a change in voltage drop between the contacts and the sensor material, and different changes in work function for areas of the sample where there are surface additives or varying thicknesses of sensor material. Additional AFM operating modes, such as force curve mapping, can be used to map the adhesion of a sensor material giving information regarding how strongly a molecule sticks to the sensor surface. For example, hydrophilic and hydrophobic tip coatings provide maps of how strongly polar molecules are attracted or repelled from the sensor surface. The relative changes in work function of a graphene sample containing single and bi-layer graphene has been mapped using environmental scanning Kelvin probe microscopy. The work function of graphene is shown to be sensitive to many atmospheric components such as O2 and water vapour and pollutants such as NO2, showing the largest response to stronger electron donating or withdrawing molecules. We demonstrate increasing sensitivity to changing environmental conditions with decreasing graphene layer thickness. A significantly larger change in the work function was observed for single layer graphene in the presence of electron donating (NH3) and withdrawing (NO2) gases than for bi-layer graphene [1]. Moreover, resistance measurements show that a single layer graphene gas sensor demonstrates a larger change in resistance than a multi-layer (MLG) graphene sensor on exposure to NO2 [2][3]. We calculate that the measured gating sensitivity difference between single layer graphene and bi-layer graphene is not fully accounted for by the difference in density of states, which is linear for single layer graphene and parabolic for bi-layer graphene. The adsorption of water vapour was observed to change the work function of single layer graphene dramatically, whereas the work function of bi-layer changed to a lesser extent over a wide range of relative humidity. We use force curve mapping to show the change in adhesion of graphene domains of different thicknesses and demonstrate that hydrophobicity increases with epitaxial graphene layer thickness. These results indicate the preferential adsorption of water vapour on single layer graphene compared to bilayer graphene. Surface contamination was also observed to preferentially deposit on either single or bi-layer graphene, which may also alter the adhesion relative properties of the graphene thicknesses. Knowledge of the affinity of environmental adsorbates to graphene and the effect they have on the electronic properties of graphene is necessary for producing environmentally stable devices as well as accurate and precisely calibrated environmental sensors. We demonstrate that a combination of effects leads to the increasing environmental sensitivity of graphene with reducing layer number. This work has implications for gas sensor research and suggests that a well-controlled and homogeneous single layer of graphene is essential in order to optimise sensitivity and uniformity of device response. AFM techniques are demonstrated to be a very useful tool in the characterisation of sensor material and devices, revealing the areas of the device most responsible for the sensor response. 1. Pearce, R.; Eriksson:, J.; Iakimov, T.; Hultman, L.; Spetz, A. L.; Yakimova, R., On the differing sensitivity to chemical gating of single and double layer epitaxial graphene explored using Scanning Kelvin Probe Microscopy. ACS Nano 2013, 7 (5) 4647- 4656 2. Pearce, R.; Iakimov, T.; Andersson, M.; Hultman, L.; Spetz, A. L.; Yakimova, R., Epitaxially grown graphene based gas sensors for ultra sensitive NO2 detection. Sensors and Actuators B: Chemical 2011, 155 (2), 451-455 3. Pearce, R.; Yakimova; Eriksson, J.; Hultman, L.; Andersson, M.; Lloyd Spetz, A., Development of FETs and Resistive Devices Based on Epitaxially Grown Single Layer Graphene on SiC for Highly Sensitive Gas Detection. Materials Science Forum, Silicon Carbide and Related Materials 2011, (717 - 720), 687-690

Authors : J. F. Feller*, M. Castro, T. T. Tung
Affiliations : Smart Plastics Group, European University of Brittany (UEB), LIMATB-UBS, Lorient, France

Resume : Spraying layer by layer (sLbL) Conductive Polymer nanoComposites (CPC) dispersions onto interdigitated electrodes is a versatile way to fabricate low cost Quantum Resistive vapour Sensors (vQRS) that can be implemented into e-noses for applications such as anticipated disease diagnosis, smart packaging or environmental monitoring. The nano-architecture of CPC transducers has been adjusted by the association of nanofillers of different shapes and natures, in order to tune the QRS macroscopic chemo-resistive properties, i.e., sensitivity and selectivity to volatile organic compounds (VOC). The synthesis of hybrids of silver nanoparticle-decorated reduced graphene oxide (Ag-RGO) prepared with poly(ionic liquid) (PIL), allowed to develop VOC transducers that can be used for environmental monitoring, as they exhibited high sensitivity to polar vapours such as methanol, ethanol, methyl acetate, acetone, water, and to a lesser extend to non-polar vapours like chloroform, dichlorobenzene, toluene, styrene. Their high signal to noise ratios (SNR up to 168 for 1 ppm of methanol) is expected to allow reaching a limit of detection in the range of ppb at least by extrapolation. These results are promising to design e-noses based on highly stable graphene QRS for emerging applications such as environmental monitoring of toxic molecules.

Authors : Giuseppe Valerio Bianco, Maria Michela Giangregorio, Maria Losurdo, Pio Capezzuto, Giovanni Bruno
Affiliations : Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, Department of Chemistry, University of Bari, via Orabona 4, 70126 Bari, Italy

Resume : The sensor properties of graphene are based on the changes in its resistivity due to the adsorption of molecules from the vapor phase that act as donors or acceptors. Indeed, perfect graphene is a relatively inert material providing weak adsorbtion energies and charge transfer with adsorbates. The sensitivity, specificity, and reversibility of graphene as vapor sensors strongly depends on the presence of structural defects and attached functional groups that can (i) locally change the surface reactivity with chemical species (also providing selective binding with specific target molecules) (ii), change the electronic state of graphene which defines the entities of the charge transfer processes between graphene and adsorbates. Thus, it is important to modify the graphene “carpet” to fully exploit its possibilities for the vapor sensing. In this contribute, we explore several approaches to fabricate graphene-based materials with tailored properties for maximizing their interaction and charge transfer with specific analites. We present data on the modification of chemical vapor deposition (CVD) graphene by thermal treatments for the introduction of heteroatoms in the graphene lattice and plasma chemical treatment for the covalent binding of functional group. The explored graphene-based materials include graphene oxide, graphane, fluoro-graphane and nitrogen-doped graphene. Their chemical and electrical properties, as required by specific sensing applications, are discussed.

Authors : A. Martucci (1), M. Cittadini (1), M. Bersani (1), F. Perrozzi (2), L. Ottaviano (2), W. Wlodarski (3)
Affiliations : (1) Università di Padova, Dipartimento di Ingegneria Industriale, Italy; (2) Università dell'Aquila, Dipartimento di Scienze Fisiche e Chimiche, Italy; (3) RMIT University Melbourne, School of Electrical and Computer Engineering, Australia

Resume : Partially reduced graphene oxide (GO) coupled with Au or Ag nanoparticles (NPs) have been used for optical gas sensing with the aim of combining the semiconducting and photocatalytic activity behavior of the GO and the Localized Surface Plasmon Resonance (LSPR) of the noble metal NPs. The synergistic interplay between these materials resulted in an enhancement of the photocatalytic properties of GO, extending them to the visible range where the LSPR of metal NPs can be used as an optical probe. The sensor has been prepared by depositing partially reduced GO flakes over a monolayer of gold or silver NPs, chemically attached to a functionalized fused silica substrate. We observed a blue-shift of the LSPR peak due to the injection of electrons into the metal NPs as a consequence of the interaction of the GO with the reducing gases (H2), mediated by the adsorbed oxygen on GO. On the other hand, the interaction with NO2 (which is an oxidizing gas) induces a red-shift in the SPR peak of the metal NPs. The sample with Au NPs showed the best sensing performances and it was also demonstrated that the coupling of Au or Ag NPs with GO can provide a wavelength-dependent sensing response for different gas, allowing the realization of a selective sensor. While the use of GO for gas sensing has been covered in multiple reports, with the GO-Au NPs system already employed as a resistive gas sensor, only very recently GO has been used in an optical fiber array for the detection of vapors and

Authors : G. Reza Yazdi1, F. Akhtar1, T. Iakimov1,3, I. Ivanov1, A. Zakharov2, R. Yakimova1,3
Affiliations : 1-Dep of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden 2-Maxlab, Lund University, S-22100 Lund, Sweden 3-Graphensic AB, Linkoping, Sweden

Resume : Graphene growth on Si face of SiC substrates was carried out in an inductively heated furnace at a temperature of 2000°C and at an ambient argon pressure of 1 atm. Graphene surface morphology, thickness, structure and electronic properties have been assessed by using AFM, LEEM, Raman, STM, STS, and EFM respectively. Sensitivity of epitaxial graphene on SiC to adsorption in open atmosphere is investigated. The surface morphology of the graphene layer shows a clean graphene surface after 1 month and completely decorated with adsorbed material after about 10 months. The aim of this work is to understand the reason of graphene surface modification. The adsorption on the surface which appears as bright spots is not uniform, the spots occur just on monolayer (ML) of graphene and not on 2ML. The second monolayer was distinguished by phase contrast mode and EFM and it is confirmed by the LEEM images as well. The EFM image of the large-scale area taken with Vtip=3V demonstrates two major levels of contrast, where the dark contrast corresponds to a single layer of graphene and the bright one to bilayer graphene On 2ML adsorption occurs on the edge of steps and wrinkles due to the geometry of the π bonds. The mechanism of this effect and dependency of their density on surface morphology will be elucidated. Strain differences between one and two monolayer graphene have been studied by Raman spectroscopy. Line Raman scanning clearly shows compressive strain in 2ML. Mapping is performed to obtain more precise results. The absence of adsorbed material on the second layer may be due to the present of compressive strain. It has been shown that the tensile strain on graphene layer makes the π bonds more active, which means in our case the compressive strain works in reverse way. To clean the graphene surfaces we have performed a series of annealing at different temperatures to find out the optimal regimes. The complete study will help to develop proper conditions for graphene maintenance before subsequent device process.

15:30 Coffee Break    
Poster Session 1: Materials for Environmental Sensing : Anita Lloyd Spetz Linköping University (Sweden) and University of Oulu (Finland) and Michele Penza, ENEA (Italy)
Authors : Ece UNUR.
Affiliations : Department of Chemistry, Bursa Technical University, Osmangazi 16190, Bursa, Turkey

Resume : Water pollution triggered by industrial revolution continues to threaten many forms of life. Synthetic dyes used in textile, paper and printing industries are the major industrial sources of water pollution. Numerous chemical, physical and biological methods, such as sedimentation, chemical oxidation, membrane separation, sorption, bacterial treatment etc. have been visited to remove contaminants from water. Among these, adsorption on activated carbons and photocatalysis have become the procedures of choice as simple, low cost, efficient and toxic-insensitive methods. While adsorption immobilizes pollutants at active carbon’s functional surface and pores, photocatalysis oxidatively degrades these organic contaminants. The major barrier to effective photocatalysis by TiO2 is the limited ability of this material to harvest sunlight due to its large band-gap energy (~3.2 eV). Carbon doping decreases the band gap energy and allows the material to harvest light over the entire UV-vis range. Adsorption of pollutants on carbon surface improves the pollutant-catalyst interaction and enhances photoactivity. Porous and magnetic C/TiO2 nanocomposites with functional carbon surfaces, prepared by green, efficient and scalable hydrothermal method at a single step in one pot, exhibit strong photoactivity. Other than that, these magnetic nanocomposites can be effectively recovered by an external magnetic field and reused.

Authors : Héctor Francisco-Rodríguez1, Julio Cesar Gonzalez-Torres2, Oscar Olvera-Neria2, Virineya Bertin1 and Enrique Poulain2
Affiliations : 1Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, México, D. F. 09340, México. 2Área de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, México, D. F. 02200, México.

Resume : Nitrous oxide (N2O) is an undesired compound for the emission control of exhaust pipe gases produced by vehicles combustion. In this way, the catalytic conversion of N2O to N2 is necessary to prevent the dangerous pollution caused. The N2O adsorption and dissociation catalyzed by octahedral and prism Rh6 nanoclusters were theoretical investigated with the density functional theory and the zero order regular approximation (ZORA). The Rh6 septet ground state is the most active in the N2O dissociation, though the spin multiplicity states in the range 1 to 9 are also active because they are degenerated or they are neighboring states. The Rh6 cluster activates spontaneously the N2─O bonding and the reaction is highly exothermic. The N2─O breaking is obtained for the N2O approaches to Rh –Rh bridge or on a Rh3 surface which are the geometrical arrangements that maximizes the molecular orbital overlap and electronic transfers between the N2O and Rh6. All N2O end-on interactions with Rh6 do not show any N2O dissociation, only capture is presented. Keywords: N2O activation; transition metal clusters; excited states; spin states; density functional theory.

Authors : R.Yatskiv, J. Grym, M.Verde, M. Hamplova, P. Gladkov
Affiliations : Institute of Photonics and Electronics, Academy of Sciences CR, v.v.i.

Resume : Over the past decade ZnO nanostructures of various shapes have been intensively investigated. These nanostructures are ideal for studying transport mechanisms in low-dimensional systems, which represent a great promise for the development of a new generation of nanodevices with high performance. A low temperature chemical method developed by L. Vayssieres(L.Vayssieres 2003 Adv. Mater.15 464-466) was used to grow ZnO nanorods (NRs). Vertical arrays of hexagonal ZnO NRs with dimensions given by the reaction time were grown in aqueous solutions of zinc nitrate and hexamethylenetetramine at 95°C on partly photoresist-masked Si and ZnO substrates. The quality of as-grown ZnO NR was checked by photoluminescence spectroscopy at different temperatures from 4 to 300 K. A layer of ZnO NRs was used for the fabrication of Schottky diodes (SDs). A Schottky contact with a diameter of about 1 mm was created by printing colloidal graphite on top of the ZnO NRs. The photoresist was removed to create a Ga-In ohmic contact on a bare substrate. SDs were characterized by the measurement of current voltage (I-V) characteristics. The values of the barrier height and of the ideality factor extracted from I-V characteristics were 0.70 eV and 3.46, respectively. Deterioration of the quality of graphite/ZnO NRs SD as compared with the graphite/ZnO SD (R. Yatskiv and J. Grym 2012 Appl.Phys. Lett. 101 162106) can be explained by the increased density of structural defects of the ZnO NRs.

Authors : Thomas J. Macdonald(a), Soundarrajan Chandrasekaran(b), Nicolas H. Voelcker(b)*, Thomas Nann(a)*
Affiliations : (a) Ian Wark Research Institute, University of South Australia Mawson Lakes, Adelaide SA 5095, Australia; (b) Mawson Institute, University of South Australia Mawson Lakes, Adelaide SA 5095, Australia

Resume : Diminishing fossil fuels and increasing carbon dioxide levels in the atmosphere are major drivers for research into renewable alternatives. Artificial photosynthesis constitutes non-natural approaches where solar energy is converted to chemical energy by following the blueprint of natural photosynthesis. This is attractive because it allows for the storage of the fuel and thus offers a solution to intermittent energy supply. A typical artificial photosynthesis device consists of a photoanode, where oxidation happens and a photocathode, the site for reduction. Each of these photoelectrodes contains a pigment (mimicking chlorophyll) and a catalyst (an analogue of the natural enzyme cascades). In inorganic-based systems, the photoanode is based on n-type semiconductors and the photocathode p-type. Catalysts may be molecular analogues of enzymes or crystalline heterogeneous catalysts. This study focuses on a new type of photocathode, which is based on porous p-type silicon, semiconductor quantum dots and a bio-inspired molecular catalyst. In our approach we built up a hierarchical nanoarchitecture, starting with a robust inorganic base material, porous p-type silicon, we then decorate this with colloidal InP quantum dots, and finally attach the molecular Fe2S2(CO)6 catalyst. This strategy resulted in a photocathode with superior performance and yielded a solar to hydrogen efficiency of 0.63%.

Authors : Aoudia Hanane
Affiliations : engineering process

Resume : The optimization of wastewater purification processes requires the development of new operations based on low-cost raw materials with high pollutant-removal efficiency. Many toxic heavy metals are being discharged into the environment as industrial wastes, causing serious soil and water pollution. The aim of this work is the removal of cadmium and lean ions from aqueous solutions using zeolite Na-X. An experimental study of the influence of some parameters, namely, the contact time, the initial concentration, temperature, pH, the amount of zeolite was carried out to allow the optimization of the elimination of this metal. The results of this study show that the method studied is highly efficient in cadmium and lead removal from aqueous solution. The both cations are better retained at low concentrations and tend to a limit value after approximately two hours of exchange. For basic pH, the process has the highest holding capacity. The cationic exchange capacity is more important at elevated temperatures and for increasing amounts of zeolithe. The sorption isotherm of both metals is of conventional type I, and kinetic study shows that the sorption of cadmium and lead follows the pseudo second order model. Keywords - zeolite, pollution, heavy metals

Authors : Gita Sakale, Maris Knite, Igors Klemenoks, Egons Skadins, Santa Stepina
Affiliations : Riga Technical University, Institute of Technical Physics

Resume : Emerging increase of different kind of sensors for gas and volatiles detection broadens the field of application of gas analysis method. Analysis of gaseous substance can give valuable information in fields like health care, food quality control, chemical and biochemical process control, cosmetics production and air quality control for health and safety reasons as well. Application of polymer nanocomposites to gaseous analyte detection has several advantages like in-situ monitoring, non-destructive, cost-effective, fast and easy measurements compared to conventional used methods. This study is about sensor material made of polymer and electro-conductive nanostructured filler. Previous research results have shown that electro-conductive grid structure of the composite has direct effect on sensitivity of the composite. Issues, which have to be considered, are type of filler, shape of aggregates (simple or complex), dispersion quality of the filler and size of the aggregates. Several hybrid polymer nanocomposites have been made by utilizing mix of two fillers: short multi wall carbon nanotubes and extra conductive, highly structured carbon black. The steady state electrical resistance of hybrid nanocomposites with defined filler concentrations has been greatly reduced comparing to composites, where only one type of filler is used, and sensitivity to gaseous analytes has been improved as well.

Authors : Umut Cindemir, Zareh Topalian, Lars Österlund, Claes-Göran Granqvist, Gunnar Niklasson.
Affiliations : Uppsala University

Resume : Formaldehyde is a volatile organic compound, which is a harmful indoor pollutant, causing sick building syndrome (SBS) and is released from household and building materials. Since higher concentrations of formaldehyde are considered to be carcinogenic, monitoring them indoors is of great importance. Advanced gas deposition has here been used to fabricate highly porous nickel oxide (NiO) thin films for formaldehyde sensing. The films were deposited on Al2O3 substrates with prefabricated comb-structured electrodes, and a resistive heater at the opposite face. The morphology of the films was investigated with scanning electron microscopy, and the porosity was determined by nitrogen adsorption isotherms with the Brunauer-Emmett-Teller method. The particle size was found to be less than 10 nm, as determined by x-ray diffraction. X-ray photoelectron spectroscopy of the NiO films was also done. Gas sensing measurements were done using a total gas flow rate of 200 ml/min. Resistivity values of sensors were recorded with formaldehyde diluted in synthetic air. Sensor resistances were recorded at 50 ppm, 25ppm, 10ppm and 5 ppm formaldehyde concentration. Measurements showed a response time of 2.5 minutes and saturation time around 20 minutes at 50 ppm. In the end, NiO films showed promising properties implying lower levels of detection limit.

Authors : Abhishek KUMAR(1,2), Jérôme BRUNET(1,2), Amadou NDIAYE(1,2), Alain PAULY(1,2), Michele PENZA(3), Christelle VARENNE(1,2), Marco ALVISI(3)
Affiliations : 1. Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand, France 2. CNRS, UMR 6602, Institut Pascal, F-63171 Aubière, France 3. ENEA, Brindisi Technical Unit of Technologies for Materials, PO Box 51-Br4, I-72100 Brindisi, Italy

Resume : Phthalocyanines are molecular semiconducting materials whose optical, electrical and chemical properties lead to many applications like dyeing, catalysis, molecular electronic or gas sensor development. Their physical and chemical properties can be modified by the grafting of the functional groups at their peripheral position or the substitution of the central atom. Thus, these materials can be adapted to different applications. This is especially attractive for chemosensors: such a sensitive material can be tailored to the pollutant to be detected and its processability can be optimized. Tetra-tert-butyl metallophthalocyanines (ttb-MPc) appear as suitable sensing materials for gas sensors aimed to aromatic hydrocarbons detection. On one hand, benzene rings of phthalocyanine macrocycle are good adsorption sites for aromatic analytes through pi-pi stacking interactions. On the other hand, peripheral butyl groups enhance the solubility of phthalocyanines into solvents, increasing the number of possible thin film deposition modes. This work reports the elaboration and the characterization of ttb-CuPc and ttb-ZnPc QCM-based sensors for the detection of benzene, toluene and xylene. Measurements are realized at room temperature, frequency drifts of QCM transducers due to temperature variations being corrected. Sensor sensitivity, stability, reproducibility, resolution and threshold have been determined. The insensitivity towards CO, H2S, NO2 and ethanol was also established.

Authors : Fatma Kayaci,a,b Sesha Vempati,*a Cagla Ozgit-Akgun,a,b Necmi Biyikli,a,b and Tamer Uyar*a,b
Affiliations : a UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey b Institute of Materials Science & Nanotechnology, Bilkent University, Ankara, 06800, Turkey

Resume : Heterostructures and their oxidative degradation of environmental pollutants is well known for their efficiency where the photo-generated charge carriers (electron and hole) are driven apart before their recombination. To design novel photo-catalyst one needs to understand the role of each charge carrier in which context we have fabricated core-shell heterojunction (CSHJ) nanofibers. Core and shell structures were fabricated via electrospinning and atomic layer deposition, respectively with ZnO and TiO2 in two combinations. In either case, only the ‘shell’ part of the CSHJ participates in photocatalytic reaction and hence they expose electrons or holes to the environment, where the band alignment governs such selection. Under suitable illumination, in ZnO-TiO2 CSHJ e/h pairs are created majorly in TiO2 and electrons take part in catalysis (i.e. reduce the organic dye) at the conduction band or oxygen vacancy sites of ‘shell’ while holes migrate to the core of the structure. Conversely holes take part in catalysis and electrons diffuse to the core in the case of TiO2-ZnO CSHJ. The results further revealed that TiO2-ZnO CSHJ shows ~1.6 times faster photocatalytic activity when compared to the ZnO-TiO2 CSHJ because of the efficient hole capture by oxygen vacancies, and lower mobility of holes. All the sample materials were thoroughly characterized via SEM, TEM, XRD, XPS, and photoluminescence.

Authors : R. Calavia, S. Roso, R. Vázquez, I. M. Szilagyi* and E. Llobet
Affiliations : MINOS-EMaS, Universitat Rovira i Virgili, Tarragona, Spain *Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Hungary

Resume : Here we discuss atomic layer deposition (ALD) to conformably coat porous anodic alumina (PAA) templates with thin films of zinc oxide (thickness up to 15 nm) in view of producing nanostructured gas sensors. The gas sensing properties of nanostructured metal oxide films, sputter-deposited on PAA templates had been studied by our group [1,2]. For such films to continuously cover the pores of PAA, a step of pore widening is unavoidable, which significantly reduces the length to width aspect ratio of pores and, therefore, surface area. In contrast, ALD allows for avoiding the pore widening step needed with sputtering and this results in nanostructured metal oxides with increased surface area. The PAA templates were obtained by the anodising of an Al/Ti bilayer in tartaric acid at a constant current density of 4.5 mA/cm2 (pore width and length were 50 and 700 nm and interpore distance was 180 nm). ALD was run at 100ºC. Diethyl zinc and water were used as precursors and 30-60-90 cycles with 0.3 s pulse and 15 s purge were performed for getting 5, 10 and 15 nm thick, amorphous ZnO films. SEM images of FIB cross sectional cuts show that a conformal coating of PAA is obtained. After an annealing step, the gas sensing properties of these films to ethanol, nitrogen dioxide both in dry and humid air were studied. Results are promising and show enhanced sensitivity at moderate operating temperatures (250ºC). [1] Int. J. Hyd. Energy, 38 (2013) 8011-8021 [2] Anal. Chem., 84 (2012) 7502-75

Authors : Amadou NDIAYE1,2, Michele Penza3, Jérôme BRUNET1,2, Marco Alvisi3, Alain PAULY1,2, Christelle VARENNE1,2
Affiliations : 1Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand, France 2 CNRS, UMR 6602, Institut Pascal, F-63171 Aubière, France 3 ENEA Technical Unit of Technologies for Materials, Brindisi Research Center, I-72100 Brindisi, Italy,

Resume : Carbon nanotubes (CNTs) present peculiar transport properties which are sensitive to surface reaction (gas adsorption). As a consequence CNTs are a judicious choice for the development of efficient gas sensors [1]. Sensing material we are developing in our study use the main advantage of CNTs i.e. their high surface area, an important property to reach higher sensitivities [2]. In terms of sensing, functionalization (non-covalent) is a good way to process the CNTs and bring additional functionalities for gas detection. Our sensing materials consist of CNTs hybrid materials obtained upon functionalization with macrocycles like porphyrins or phthalocyanines to achieve VOCs (Volatile Organic Compounds) detection like Benzene, Toluene and Xylenes. To understand the gas/material interaction between VOCs and CNTs hybrid materials, we have performed two studies: first, we have simultaneously investigated QCM and SAW transduction modes, and second, we have proceeded to gas sensing experiment towards interfering gases (NO2, H2S, and Ethanol etc). The sensing materials were prepared and characterized by standard techniques (UV-Vis spectroscopy, TGA, TEM, Raman analysis). The results have provided information on the ability of these CNTs-based hybrid materials to detect VOCs while they seem to be insensitive towards other interfering gases, at room temperature. References: [1] S. Liu Coord. Chem. Rev. 254 (2010) 1101. [2] A.L. Ndiaye Sens. Actuators B 162 (2012) 95.

Authors : C. Bilel*, M. M. Habchi, A. Rebey, and B. El Jani
Affiliations : University of Monastir, Faculty of Sciences Unité de Recherche sur les Hétéro-Epitaxies et Applications (URHEA), 5019 Monastir, Tunisia E-mail: *

Resume : The effect of an applied stationary electric field on the band structures of GaNAsBi/GaAs quantum wells has been investigated using self-consistent calculations. Such study based on the optimization of N and Bi contents can be useful to improve physical proprieties of emitters or photodetectors devices operating at 1.55 µm. We have examined the quantum confined Stark effect on the shape of the confining potential, the Fermi level, the subband energies and their corresponding wave functions as well as their occupations, and the charge density distributions. We have also determined the oscillator strength and the absorption coefficient of the inter-subband transitions and their dependences on the applied perturbation. Keywords: Stark effect; GaNAsBi/GaAs QWs; band structures; self-consistent calculations.

Authors : S. Roso, F. Guell*, E. Llobet
Affiliations : MINOS-EMaS, Universitat Rovira i Virgili, Tarragona, Spain *Departament d'Electronica, Universitat de Barcelona, Barcelona, Spain

Resume : Zinc oxide (ZnO) is an interesting material with optoelectronic and gas-sensitive properties. Here we have synthesized ZnO nanowires (NWs) via the vapor-liquid-solid technique. This is a catalyst assisted chemical vapor deposition suitable for obtaining good quality NWs. We have chosen sapphire substrates with different crystallographic orientations, namely, c-plane, r-plane and a-plane. Au clusters were previously deposited on the substrates by sputtering and annealing. Then, 40 nm wide and 1 micro long nanowires were grown at 900?C in a horizontal quartz furnace, using ZnO powder and graphite as precursors and Ar as carrier gas. NWs grew oriented in different directions or with different morphologies depending on the crystalline planes of the substrates. For example NWs grew at 51? and 129? (on c-plane substrates), vertically aligned (on a-plane) or showing a nanorod structure (on r-plane). The response of ZnO NWs to different gases and concentrations was tested at different working temperatures. The optimum operating conditions have been identified and the dependency of the gas response on the orientation of NWs has been studied (higher gas response is observed for r-plane and a-plane samples). Full details on growth mechanisms, morphology, crystalline phase and gas response to CO, C6H6 and EtOH will be given. Enhanced response can be due to the lower amount of NW to NW contacts and higher specific surface found in samples that grow vertically aligned.

Authors : Zixian JIA, Mounir BEN AMAR, Arlette VEGA, Xavier DUTEN, Andrei KANAEV
Affiliations : LSPM ; Universite Paris-Nord 13, Sorbonne Paris Cite, CNRS, Villetaneuse, France; LPP, Ecole Polytechnique, UPMC, Universite Paris sud 11, CNRS, Palaiseau, France

Resume : In our previous studies, we have reported a new method of preparation of Ag/TiO2nanoparticulate coatings with stable and highly reproducible morphology and studied the degradation of acetaldehyde using a process coupling NTP and this catalyst. Our later studies were directed to enhance the process efficiency and selectivity and to correlate these factors with the deposited noble metals mass and morphology. In this communication, acetaldehyde decomposition was investigated in a diphasic process coupling NTP and a fluidized nanostructured gold-based bed. We show that the size and distribution gold particles strongly affect the acetaldehyde degradation. Compared to silver catalysts, the same quantity of the input pollutant can be decomposed with Au NPs catalysts in similar experimental conditions. In the same time, utilization of the gold catalyst enhances the process selectivity towards CO2 and diminishes formation of by-products like acetic acid, nitromethane and acetonitrile. We introduce a new term, specific pollutants removal efficiency, which characterize the catalyst activity and permits to understand the catalysts morphology influence on the plasma-catalytic process.

Authors : Zeggai Oussama , Ould-Abbes Ammaria , Zeggai Hichem
Affiliations : Research unit of Materials and Renewable energies (URMER), University Abou Bakr Belkaïd, B.P. 119, Tlemcen, Algeria

Resume : Semiconductor nanowires are nano-objects to a very promising dimension for the realization of future high-performance electronic components. The development of semiconductor nanowires (ZnO) has been a great interest in the scientific community over the past ten years. These one-dimensional objects have been developed using various techniques such as molecular beam epitaxy or vapor phase epitaxy. The ZnO is one of the attractive semiconductor due to their excellent electrical and optical properties (large exciton binding energy, very large gaps to the emission and detection of light in the UV, for surface functionalization the realization of biological sensors, etc. ....). The possibility to study recently nano-objects ZnO resulted in a large number of scientific works in the field of biology and health. In this work we demonstrate the role of electrical and electrochemical properties of nanowires (ZnO), and the contact with the biological catalysts such as enzymes in biological solutions for the detection of analytes (glucose, CO2 ....).

Authors : I. Veselova, N. Borzenkova, O. Vashkinskaya, T. Shekhovtsova, A. Sidorov, A. Grigoryeva, E. Goodilin
Affiliations : Lomonosov Moscow State University, Moscow, Russia

Resume : The creation of sensitive and selective sensor systems for the determination of different biologically active compounds (phenols, flavonoids, catecholamines, phenothiazines, dibenzothiophene and its oxidation products, and organic peroxides) without preliminary pretreatment of samples with complex matrices is the promising direction of modern biochemical analysis. The determination of such compounds is necessary to control the quality of pharmaceutical and food products, plant materials, diesel oil, environmental samples and etc. In the present work the solid-phase biosensors with photometric, fluorescent and SERS detection of an analytical signal were developed. The action of the proposed photometric, fluorescent biosensors is based on the molecular recognition of the above mentioned analytes by horseradish peroxidase included into a self-assembled optically transparent film or hydrogel of a biopolymer (chitosan). The main peculiarity of the proposed biosensors is the measurement of the analytical signal as an absorbance or emission of a glass slide with biorecognizing films {polyelectrolyte-enzyme-photometric or fluorescent reagent}. The solid-phase photometric and fluorescent indicator systems for each group of the above mentioned analytes (twelve systems totally) were elaborated. The novel approach for detection of SERS “invisible” molecules (such as dibenzothiophene and its oxidation products) based on formation of charge–transfer complexes with different substituted benzoquinones immobilized in chitosan films was developed. This investigation was financially supported by RFBR (Projects 12-03-00249-а, 13-03-00441-a, 14-03-01151-a).

Authors : K. F. KAM, J. K. YUAN
Affiliations : The Hong Kong Polytechnic University

Resume : This project aims to develop new low-cost inorganic nanowire membrane composites for the treatment of polluted water, typically containing oil spills, heavy metal ions, and organic compounds. The whole process consists of pretreatment polluted water using coated MnO2 nanowire membranes for selectivity absorbing hydrophobic organic compounds followed by ion-exchange processes based on acid manganese dioxide octahedral molecular sieve nanowire membrane with strong ion-exchange capabilities. The multifunctional highly-selective absorbent membrane materials could be an ideal candidate for the separation and removal of pollutants in water, and the applications of the nanowire multifunctional membranes could lead to a significant reduction of energy consumption through low-pressure-permeability. The choice of membrane materials, Alpha-MnO2, with unique properties including high selectivity for solvents that need to be separated, high surface area and permeability, good mechanical and thermal stability, good chemical stability, good ion-exchange properties and low cost of the membrane materials.

Authors : Oral Ualibek, Ruggero Verre, Ehsan Razvani, Brendan Bulfin, Karsten Fleischer, Igor V. Shvets
Affiliations : Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Physics, Trinity College Dublin, Dublin 2 , Ireland; Department of Applied Physics, Chalmers University of Technology, Goteborg, Sweden; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Chemistry, Trinity College Dublin, Dublin 2 , Ireland; School of Physics, Trinity College Dublin, Dublin 2 , Ireland

Resume : Highly ordered self-assembled plasmonic nanoparticle (NP) arrays have been produced by glancing angle deposition (GLAD) on faceted c-plane Al2O3 templates. This procedure allows for engineering and tuning of their optical and geometrical properties via control of growth parameters. The NP shape can be tuned by changing the substrate temperature during deposition. The structures showed a strong optical anisotropy in the visible region, with a shift between longitudinal and transverse resonances. This phenomenon has been attributed to the combined effects of both shape anisotropy and strong inter-particle interaction. Due to the presence of “hot spot” areas in the inter-particle sites, the structure is appealing for surface enhanced Raman spectroscopy measurements and biosensing applications. The average NP diameter and inter-particle distance are below the limitations of lithographic methods, with standard deviations of ~20%. We could tune the plasmonic resonance peak within the range of 1.1 eV to 2.6 eV by changing the material of the nanoparticles, their size and shape. Thus, engineering of the optical properties of the array is readily achievable by the versatile GLAD method. With regard to the application potential of the GLAD technique, we present SERS results in which the Raman signal achieves an enhancement factor of 10^7 due to the presence of the underlying NP arrays.

Authors : M.C. Sportelli1, D. Hoetger2, R.A. Picca1, K. Manoli1, C. Kranz2, B. Mizaikoff2, L. Torsi1, N. Cioffi1
Affiliations : 1 Chemistry Department, Univ. degli Studi Bari Aldo Moro, Italy 2 Institute of Anal. and Bioanal. Chemistry, University of Ulm, Germany

Resume : ZnO is one of the most important functional oxides. The electrochemical synthesis of ZnO is particularly interesting as green, cheap and easy procedure1. Application of ZnO to fabricate gas sensors is widespread: the key-issues hereby is the development of smart ZnONPs with tailored properties for solid-state sensors2. Here we report on the galvanostatic aqueous electrosynthesis of ZnONPs3 in the presence of sodium polystyrensulfonate, often used as stabilizer for NPs in sensing applications4. Calcination of colloids was carried out at 300/600°C. All nanomaterials were characterized by TEM, UV-Vis, IR and XPS. Detailed investigation of photoelectronic and Auger XPS spectra was accomplished. We prepared high-performance OFETs, by preparing a poly-3hexyltiophene (P3HT)-ZnO multilayered composite with improved electronic figures of merit in respect to bare P3HT devices5; preliminary successful experiments on the use of ZnONPs in biosensors devices were carried out. 1. M.C. Sportelli, et al., Recent trends in the electrochemical synthesis of ZnO nanocolloids, in CRC Concise Encyclopedia of Nanotech., submitted. 2. B.Bhooloka Rao, Mat. Chem. Phys. 2000, 64, 62-65. 3. K.G. Chandrappa et al., Nano-Micro Lett. 2012, 4, 14-24. 4. L. Wan, et al., Coll. Surf. A 2012, 396, 46–50. 5. M. D. Angione, et al., PNAS 2012, 109, 6429–6434.

Authors : O. Darčanova, A. Begansksienė, A. Kareiva
Affiliations : Department of Inorganic Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania

Resume : Documents, books and artworks from paper are slowly degrading due to the inherent ageing of the cellulose substrate or the technological errors of the past (acid paper, iron gall ink). The main stabilization procedure of damaged documents ? deacidification process. Aqueous solutions of calcium and magnesium compounds have been widely used for many decades, and nanoparticles of calcium hydroxide just started to be used for wall painting conservation. Smaller size of particles should ensure greater penetration efficacy in panted surface layer, so same have to be with paper fibres. The aim of study was the preparation of suspension of nano-Ca(OH)2 particles suitable for paper deacidification. According sol-gel method prepared solution was tested and compered with currently widely used deacidification methods ? commercial Bookkeper and Ca(OH)2 prepared by Barrow method. Suspensions of obtained particles were used for cotton paper treatment. Treated samples with nano-Ca(OH)2 were aged at 90 0C for 512 h. The pH values and alkaline reserve results of treated paper showed that synthesized nano-Ca(OH)2 compound with stabilization of gelatin are more effective for paper conservation than Bookkeeper or commercial Ca(OH)2. The data of infrared spectroscopic analysis showed that all deacidification systems reduce the formation of the acidic species on the paper surface.

Authors : Elena Dilonardo 1, Michele Penza 2, Marco Alvisi 2, Domenico Suriano 2, Gennaro Cassano 2, Francesco Palmisano 1, Luisa Torsi 1, Nicola Cioffi 1
Affiliations : 1 Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Campus Universitario, via Orabona 4, 70126 Bari, Italy 2 ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic DevelopmentTechnical Unit for Materials Technologies - Brindisi Research Center, PO Box 51 Br4; I-72100 Brindisi -Italy

Resume : A facile one-step strategy based on sacrificial anode electrolysis was developed to obtained stabilized gold nanoparticles (Au NPs) directly deposited on the surface of nanostructured ZnO and ZrO2 powders, previously synthesized by sol-gel method and subjected to thermal annealing prior to the electrosynthesis step. The resulting nanocomposite is proposed as active layer in resistive sensors for NO2 detection. The nanostructured composite materials were firstly thermally annealed under mild conditions and, subsequently, they were morphologically and chemically characterized using transmission and scanning electron microscopies, as well as X-ray photon electron spectroscopy which revealed the formation of nanoscale gold, and its successful decoration on metal oxide nanoparticles. Au functionalized metal oxide thin films were tested as active layers for NOx sensing application. Nitrogen dioxide sensors based on drop-casted Au-doped and un-doped metal oxide (MOX) thin films were prepared. The effect of the metal oxide composition and of the Au-doping on the sensor performance (e.g., gas response and baseline resistance drift) were analyzed. In particular, the gas sensing properties of MOx and hybrid nanostructured thin films were studied at various temperatures for a wide range of concentration for analyzed gas. Moreover, the response of these sensors towards some interfering species such as CO, NH3, CH4 and SO2 were also analyzed.

Authors : Hyun Kim, Bee Lyong Yang
Affiliations : School of Advanced Materials and System Engineering, Kumoh National Institute of Technology

Resume : Solar hydrogen generation via water splitting is a promising technology for a renewable clean energy which has attracted much attention in the past decade [1–3]. Up to now, mainly n-type semiconductor photoanode and Pt cathode PEC cell configuration systems have been extensively studied. However, the n-type semiconductor/Pt system requires application of external bias for effective operation. Therefore, development of PEC cell that does not require external bias is critical for efficiently converting the solar energy. Use of the above system to generate hydrogen from water without applying an external bias requires p- and n-type semiconductor electrodes [4]. Titanium dioxide (TiO2) has been considered as one of the promising candidates as a n-type photoanode, due to its high chemical stability, proper band edge positions, and inexpensive cost. On the other hand CuO can be utilized as a p-type semiconductor due to its narrow bandgap and suitable band configuration. However, to reduce a proton requires high overpotential on CuO. Thus co-catalysts are necessary to reduce overpotential for hydrogen generation on CuO. In this work, we demonstrate fabrication and analysis of Pt nanoparticles deposited CuO nanosheets on FTO glass substrate as a p-type photoelectrode. Morphology and microstructural properties of the CuO and TiO2 electrodes were examined by FE-SEM, XRD and HRTEM analysis. Photocatalytic properties of both electrodes were confirmed by measuring photocurrents responses under both white and visible light illumination. Furthermore, operation conditions of PEC cell with Pt-CuO and Pt-TiO2 electrodes that can generate hydrogen and oxygen gases without external bias will be discussed. 1. A. Fujishima and K. Honda, Nature, 37, 238 (1972) 2. A. Ryu, J. Photochem Photobiol C: Photochem. Rev., 11, 179 (2010) 3. A. Kudo and Y. Miseki, Chem. Soc. Rev., 38, 253(2009) 4. S. Ida, K. Yamada, T. Matsunaga, H. Hagiwara, Y. Matsumoto, T. Ishihara, J. Am. Chem. Soc., 132, 17343(2010)

Authors : Pragati Thakur, Kirti Shitole
Affiliations : Department of Chemistry, University of Pune, Pune, India

Resume : The TiO2-Sb2S3 semiconductor heterojunction promotes the charge separation of electron-hole charges generated upon light irradiation. This enhancement in charge separation depends on the quality of interfacial contact between Sb2S3 and TiO2, their composition, their morphological and surface properties. In this study, the TiO2-Sb2S3 nanocomposites were synthesized by two different methods (hydrothermal and mechanical mixing method) with different percent composition (5-20% of Sb2S3) and with different calcinations temperatures (200-600 oC) to study their effects in improving the interfacial contact between both semiconductors. Among all synthesized samples, hydrothermally synthesized 10% TiO2-Sb2S3 nanocomposite calcined at 300 oC shows the highest photocatalytic degradation of (Methyl orange) MO dye solution under UV light irradiation. XRD shows the anatase phase of TiO2 and orthorhombic phase of Sb2S3 retains in the nanocomposite. SEM and EDX reveal the formation of nanocomposite with purity. TEM reveals that TiO2 is well deposited on Sb2S3 in hydrothermally synthesized nanocomposite than the one formed by mechanical mixing. However 300 oC calcinations help to improve the interaction between Sb2S3 and TiO2. BET surface area analysis shows the highest specific surface area for the hydrothermally synthesized 10% TiO2-Sb2S3 nanocomposite calcined at 300 oC. Considering all the results of the present study a reasonable mechanism of photocatalysis on TiO2-Sb2S3 nanocomposite under UV light has been proposed.

Authors : Hyun Kim, Bee Lyong Yang
Affiliations : School of Advanced Materials and System Engineering, Kumoh National Institute of Technology

Resume : The hydrogen is a promising eco-friendly energy, due to its high potential such as to reduce a usage of fossil fuel, easy storage than others and high energy density. Many researchers have studied to produce hydrogen via split water into hydrogen and oxygen in the past decade [1–3]. Until now, most metal oxides show a n-type properties due to oxygen vacancy. However, to reduce a proton to hydrogen at interface between n-type metal oxides and electrolytes requires a high potential due to n-type band is bended upward to electrolytes. Thus it is necessary that switching a direction of bend bending to downward to decrease a potential. What the key point which can switch is a fabrication of p-type metal oxides. In this work, we demonstrate fabrication and analysis of CuFe2O4 on FTO glass substrate as a p-type photoelectrode. Morphology and microstructural properties of the CuFe2O4 electrodes was examined by FE-SEM, XRD and HRTEM analysis. Photocatalytic hydrogen production was confirmed by measuring photocurrent density, IPCE and GC under both white and visible light irradiation. 1. A. Fujishima and K. Honda, Nature, 37, 238 (1972) 2. A. Ryu, J. Photochem Photobiol C: Photochem. Rev., 11, 179 (2010) 3. A. Kudo and Y. Miseki, Chem. Soc. Rev., 38, 253(2009)

Authors : S. Vallejos, F. Annanouch, E. Llobet, E. Figueras, C. Canè, I. Gràcia
Affiliations : Instituto de Microelectrónica de Barcelona (IMB-CNM), CSIC, Barcelona, Spain; MINOS-EMaS, Department d'Enginyeria Electrónica, Universitat Rovira i Virigili, Tarragona, Spain

Resume : Tungsten oxide nanostructures functionalized with either Au or Pt nanoparticles are co-deposited directly on microsensor arrays via localized Aerosol Assisted CVD. In this work the evaporation and reaction of the aerosol droplets is promoted by using the self-heating capability of the microsensor platforms and maintaining the reaction chamber at room temperature, unlike to our previous reports in which a ‘hot wall’ reactor was used [1-2]. Localized heating for CVD synthesis is used to confine the required thermal environment for the decomposition of the vapor phase reactant and the growth kinetics of nanostructures to a microscale area, with the aim of maintaining the microelectronics-compatible thermal environment elsewhere. Our results demonstrate the viability of this deposition technique to integrate uniform functionalized nanostructured films on microsensor arrays, obtaining similar properties to those deposited in ‘hot-wall’ reactors. The microsensors fabricated using this method show improved sensitivities to H2 (500, 200, 80, 20 ppm), CO (500, 200, 80, 20 ppm) and EtOH (80, 40, 60, 20 ppm), with microsensors based on Pt-functionalized tungsten oxide nanostructures showing improved responses towards H2. This method provides great potential for simple integration of functional nanomaterials on microsensor devices and reduces both material and power consumption in device manufacture [1] Chem. Commun. 2011, 47, 565 [2] Adv. Funct. Mater. 2013, 23, 1313

Authors : Nana Qian, Liping Gao, Feihu Zhang, Jun He, Nan Qin, Jiaqiang Xu
Affiliations : Shanghai university,China

Resume : Nowadays, BTEX (benzene, toluene, ethylbenzene, and xylol) has received a great deal of attention owing to their frequent detection in high concentration in environments (urban outdoor and indoor) and their health hazards. High indoor pollution concentration has been associated with sick building syndrome symptoms such as eye irritation, dizziness, headache and nausea. The permissible exposure limit has been lowered from 10 ppm to 100 ppb in the last 10 years due to relationships between the contaminants and disease. The monitoring of BTEX in our daily life has attracted lots attentions in sensor field. Researchers have done many great works for BTEX detection. Recent results showed that BTEX could be detected by using sensing materials based on SnO2, WO3, phenylene-silica, porphyrins and metal-decorated MWCNT. However, an easy-synthesized sensing material with both good sensitivity and selectivity for BTEX is still a challenge. SnO2 is one of the most popular gas-sensing materials owing to its considerable response to lots of gases, but indicating its poor selectivity. Normally, to get a high selectivity for a specific gas, researchers usually adjust its morphology or exposed face and composite it with other metallic oxide. V2O5 is usually used as an organic chemical catalyst, and it is an activator for benzene ring. Under certain condition, catalyst V2O5 could make solid benzene ring fracture. The product after benzene ring fracture with high activity resulted in a high gas sensitivity. In order to achieve a good sensing material with both great sensitivity and high selectivity for BTEX, especial for benzene, activating the benzene ring is essential. We chose SnO2 as a main sensing material and V2O5 as a catalyst to detect BTEX. We designed series SnO2/V2O5 composites sensing material for selectively sensing BTEX (benzene, toluene, ethylbenzene, and xylol) based on a catalytic oxidation reaction. The sensing materials were prepared by impregnation method. V2O5 nanobelts and SnO2 nanospheres were prepared through a hydrothermal method, respectively. XRD, SEM and TEM are employed to characterize the composites. The TEM results revealed that the as-prepared SnO2 take on nanosphere morphology with maximum size of 100 nm and the V2O5 show nanobelt shape with the length of several microns. Gas sensing results of side-heating sensor showed that the SnO2/V2O5 composites had a much better response to BTEX rather than other VOCs such as ethanol, acetone, methanol, methanol and acetic acid compared with pure SnO2. Among the series composites of SnO2/V2O5, the composite containing 3% V2O5 has the best selectivity and sensitivity for BTEX. At 270 ?C, an optimal working temperature, the values of gas response to 50 ppm (parts per million) BTEX are more than 5, meanwhile the limit of detection is as low as 0.5 ppm.

Authors : Federica Rigoni(ab), Silvia Tognolini(ab), Patrizia Borghetti(bc), Giovanni Drera(ab), Stefania Pagliara(ab), Andrea Goldoni(d), Luigi Sangaletti(ab)
Affiliations : (a)Interdisciplinary Laboratories for Advanced Materials Physics (I-LAMP), via dei Musei 41, Brescia, Italy; (b)Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, via dei Musei 41, Brescia, Italy; (c)Centro de Fisica de Materiales CSIC/UPV-EHU-Materials Physics Center, E-20018 San Sebastian, Spain;‏ (d)Elettra Sincrotrone Trieste S.C.p.A., s.s.14 Km. 163.5, 34149, Trieste, Italy

Resume : Novel perspectives in the development of chemiresistor gas sensors (CGS) are determined by the possibility to meet the requirements of environmental monitoring, in particular (i) the sensitivity in the low ppb range and (ii) the capability to detect the polluting gas molecule on a background of water molecules brought about by the humidity conditions. We present single-wall carbon nanotube (SWCNT) CGS operating at RT, displaying an enhanced sensitivity to NH3. Different materials were tested as substrates, including cheap plastic flexible substrates, and also possible functionalizations have been explored. Ammonia concentrations in air as low as 20 ppb have been measured, and a detection limit of 3 ppb is demonstrated [1], which is in the full range of the average NH3 concentration in a urban environment and well below the sensitivities so far reported for non-functionalized SWCNT operating at RT. In addition to a careful preparation of the SWCNT layers, the low-ppb limit is also attained by revealing and properly tracking a fast dynamics during the desorption process. On the basis of these results a model of the CGS response vs time is proposed. When functionalized with ITO nanoparticles, a sensitivity increase is detected, along with a remarkable selectivity towards water molecules. The response to humidity is rationalized on the basis of the extent of charge transfer to SWCNT upon molecule adsorption. This work was funded by COST – EuNetAir. [1] Analyst, 2013, 138, 7392

Authors : Yongde Xia,1 Fenghua Bai,1,2 Binling Chen,1 Yanqiu Zhu1
Affiliations : 1 College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom 2 School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, Inner Mongolia, People’s Republic of China

Resume : The ever-increasing emission of CO2 from the combustion of fossil fuels, a major greenhouse gases that contribute to global warming, has triggered worldwide concerns on atmospheric environment and made it compelling to reduce CO2 emissions into air. It is therefore highly desirable to develop high performance CO2 adsorption materials which may help to debase CO2 emission. Porous materials are attractive CO2 adsorbents due to their high surface area and large pore volume that can facilitate to host plenty of CO2 gas. Among diverse porous adsorbents, porous carbon-based materials with alkaline functional groups such as N species on their surfaces is one of the most promising candidates for CO2 storage, due to their intrinsic properties such as low cost, ease of preparation and regeneration. Various synthesis approaches have been developed to generate porous carbons with controlled pore structures; there are, however, seldom studies on porous carbons derived from direct carbonization of metal-organic frameworks as CO2 uptake adsorbents. Herein, we report our systemic work on the preparation of porous carbon materials via direct carbonization of ZIF-8 under various conditions and on the evaluation of their CO2 uptake performances. The effect of carbonization conditions on the textural properties and their CO2 uptake capacities of the ZIF-derived porous carbons are addressed for the first time. The resulting porous composites (before removal of the inorganic species) and carbon materials are characterized by a variety of techniques and their adsorption capacities for CO2 are compared. The influence of both textural properties and surface chemistry on the CO2 capture performance of the resultant porous adsorbents is discussed.

Authors : M. Govender1,2, B. W. Mwakikunga1, A. K. Prasad3, S. Umapathy4, S. Sil4, A. J. G. Machatine2, H. W. Kunert2, S. Mathur5, T. Singh5, Y. Gönüllü5, R. Müller5, E. Manikandan6
Affiliations : 1DST/CSIR National Centre for Nano-Structured Materials. CSIR. P. O Box 395, Pretoria, 0001, South Africa, 2Department of Physics, University of Pretoria, Pretoria, 0002, South Africa; 3Surface and Nanoscience Division, IGCAR, Kalpakkam, 603102, India; 4Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India; 5Department für Chemie, Lehrstuhl für Anorganische und Materialchemie, Universität zu Köln, Greinstraße 6, D-50939 Köln, Germany; 6Department of Physics, B.S. Abdur Rahman University, Chennai-600048, India

Resume : WO3 film was RF-sputtered with Ar-plasma on Al2O3 from a pure WO3 target. The amorphous WO3 containing small amounts of carbon was used for gas-sensing because the annealed sample was found to be stoichiometric and insulating WO3 according to current-voltage (IV) measurements and XPS. The amorphous WO3 sensed NO2 from concentrations as low as 20 ppm and NH3 from concentrations as low as 30 ppm at an optimum sensing temperature of 200oC. Temperature studies were carried out on the WO3 sample using thermogravimetric analysis and the vibrational properties and electrical properties were investigated using Raman spectroscopy and IV-curves as a function of temperature, respectively. Theoretical studies were also carried out on WO3 as a function of temperature, because it is well-known that this compound exhibits temperature-dependent crystal phases, and these phases can influence the gas-sensing mechanism. From powder neutron diffraction, we have found several different phases of WO3. At temperatures above 910oC, the symmetry falls under space group P4/nmm (D4h-7). As the temperature is lowered, WO3 exhibits orthorhombic, monoclinic and triclinic phases. We have used the rigid thermodynamical method which involves Landau-Lifshitz theory to identify the correct symmetry of modes responsible for second order phase transitions. The symmetries of (S.O.Ph.Tr.) modes before and after transitions can be precisely measured by Raman and I-V spectroscopy.

Authors : M. Filipescu, A. Palla-Papavlu, A. Matei, B. Mitu, V. Ion, F. Stokker-Cheregi, M. Dinescu
Affiliations : Department of Lasers, National Institute for Laser Plasma and Radiation Physics, 077125 Magurele, Romania

Resume : Due to high specific surface area and capability to convert chemical interactions into electrical signals, polyaniline (PANI) mixed with tungsten oxide nanoparticles (WO3) is a compound that can be used in sensors applications. Thin films of this composite were obtained by Matrix Assisted Pulsed Laser Evaporation technique. A frozen target consisting in a mixture of polyaniline, WO3 nanoparticles (different concentrations) and xylene solvent was irradiated with a Nd:YAG laser working at 266 nm wavelength. The surface morphology was in detail studied by Atomic Force Microscopy and Scanning Electron Microscopy and the chemical bonding was investigated by Fourier Transformed Infrared Spectroscopy. The influence of PANI/WO3 ratio on the electrical properties was studied and gas tests in ammonia have been carried out for detecting layers sensitivity.

Authors : Z. Zelinger, P. Janda
Affiliations : J. Heyrovský Institute of Physical Chemistry AS CR, v.v.i., Dolejškova 3, 182 23 Prague 8 Czech Republic

Resume : Graphene leafs have outstanding electromechanical properties and impressive sensitivity as a mass detector. Its mechanical properties offer utilization as nano/micro-levers. These levers could work as extremely sensitive pressure sensors or mass detectors. Such types of sensing devices for chemical analysis are important challenges [1]. Micro-levers as pressure sensors in the form of silicon cantilevers enhanced the sensitivity of laser photoacoustic spectroscopy (PAS) [2]. We have used laser PAS for sensitivity testing of different AFM-based silicon cantilevers and graphene sheets. Graphene sheets have been prepared from multilayer graphene (MLG) by micromechanical cleavage of basal plane highly ordered pyrolytic graphite [3]. MLG leafs (thickness <10 mm) have been mounted on an additional glass window of cuvette for PAS. Movements of leafs induced by an acoustic wave have been measured by the He-Ne laser beam reflected to a quadrant detector. A discretely tunable CO2 laser and NIR diode lasers have been used as sources of radiation energy for the laser PAS. Quantitative sensitivity testing of investigated sensors has been based on concentration standards and mixing arrangement in a flow regime. The combination of sensitive microphones and micro/nano-mechanical elements with advanced laser techniques offers us a precise method for development of reliable and highly sensitive chemical sensing system. 1. P. Li, Z. You, T. Cui, Appl. Phys. Lett., 101, (2012) Issue 9, id. 093111. 2. J. Kauppinen, K. Wilcken, I. Kauppinen, V. Koskinen, Microchem. J. 76 (2004)151-159. 3. Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. (2004). Science 306 (5696): 666–669.

Authors : Fabrizio Caprioli, Paolo Di Lorenzo, Domenico Palumbo, Iole Venditti, Ilaria Fratoddi, Maria Vittoria Russo, Luigi Quercia
Affiliations : ENEA Centro Ricerche Casaccia; ENEA Centro Ricerche Casaccia; ENEA Centro Ricerche Casaccia; Dipartimento di Chimica Università La Sapienza di Roma; Dipartimento di Chimica Università La Sapienza di Roma; Dipartimento di Chimica Università La Sapienza di Roma; ENEA Centro Ricerche Casaccia

Resume : Ethylene (C2H4) is a vegetal hormone playing a key role in several fundamental processes. Among other things, its concentration can be used to assess the ripening stage of climacteric fruits, making its detection a very topical issue in post harvest technology. Up to now, the quantification of C2H4 has been mainly achieved by sensors based on semiconducting oxides such as SnO2 or WO3 which, however, present some intrinsic drawbacks such as the scarce selectivity and the high operation temperature. In the present study we tested several insatured polymers as novel active material for ethylene detection. In order to increase their surface area, the materials have been prepared in nanostructured form by means of a simple osmosis based method. Moreover, to enhance their sensitivity and selectivity toward the analyte, they have been decorated with Cu(I) salts, to take advantage from the good affinity of ethylene for d9 transition metal ions. The polymers have been deposited from solution onto interdigitated electrodes (IDEs) and their capacitance has been determined at room temperature as a function of ethylene concentration by means of impedance measurements. The observed detection limit has proved suitable for a possible application in post harvest technology. On the basis of the obtained results, these materials appear good candidates for the development of wireless sensors based on RFID technology.

Authors : Xu Yong, Hu Xue Feng, Wang Rui , Li Tao,Qin Wei Wei, Xu Meigui, and Wei Zhang*
Affiliations : State Key Laboratory of Material-oriented Chemical Engineering and School of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China

Resume : The increased emission of carbon dioxide (CO2) and other greenhouse gases since the mid-20th century has been thought to be the cause of the increase in the average near-surface air and ocean temperature of the earth, a phenomenon known as global warming. Efforts are being undertaken to mitigate the greenhouse gas concentration by monitoring and subsequently reducing CO2 emission from the combustion of fuel in vehicles and the burning of coal in power plants. Therefore, it is important to develop low-cost, sensitive, resettable sensors that can be used to monitor the CO2 concentration in industrial exhaust gases. In this article, we report on a high-performance hydrided graphene and ZnO carbon dioxide (CO2) gas sensor fabricated by pulsed laser ablation and grapheme transfer technology. Unlike other solid-state gas sensors, the graphene sensor can be operated under ambient conditions and at room temperature. Changes in the device conductance are measured for various concentrations of CO2 gas adsorbed on the surface of grapheme and ZnO films. The conductance of the grapheme gas sensor increases linearly when the concentration of CO2 gas is increased from 10 to 100 ppm. The advantages of this sensor are high sensitivity, fast response time, short recovery time, and low power consumption. *Corresponding author,

Authors : Umut Cindemir, Zareh Topalian, Raul Calavia, Eduard Llobet, Claes-Göran Granqvist, Radu Ionescu
Affiliations : Uppsala University, Uppsala, Sweden. Rovira i Virgili University, Tarragona, Spain

Resume : People spend most of their time indoors, in buildings and vehicles, and therefore it is important to monitor the indoor air quality for health and well-being. Volatile organic compounds (VOCs) are pollutants causing sick building syndrome that exist in buildings, and high concentrations can be carcinogenic. Formaldehyde is such a VOC, which is moreover found in the breath of lung cancer patients. Gold nanoparticles (Au NPs) with organic compounds were fabricated and tested for the detection of this VOC. Firstly, dispersed Au NPs were prepared and deposited by means of advanced gas deposition, which allows controlling the size of NPs with a narrow distribution. They were examined via scanning electron microscopy (SEM) and X-ray diffraction to determine morphology and particles size. Next, the Au NPs were functionalized with several organic materials: 1-butanethiol, 1-decanethiol, 1-dodecanethiol and 4-methoxy-alpha-toluenethiol. SEM images taken again on the sensing films showed changes in particles arrangement. Materials characterization was completed by X-ray photoelectron studies. Sensors responses to different concentrations of formaldehyde were recorded and compared. Note:Author for correspondence is Radu Ionescu (

Authors : Qin Wei Wei, Wang Rui, Gao Zhi Qiang, Li Tao, Hu Xue Feng,Xu Meigui, Huang Shengming, Liang Qi, and Wei Zhang,*
Affiliations : a State Key Laboratory of Material-oriented Chemical Engineering and School of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, PR China b School of Physical Science, Hefei University of Technology, Hefei, Anhui 230009, PR China

Resume : Recent discovery in ZnO nanogenarator has spurred tremendous interest in micro-sensor power application. The fundamental principle of ZnO nanogenarator is to utilize the environmental mechanical energy, which is available everywhere from irregular vibrations, light airflow, noise and human activity with a wide spectrum of frequencies and time-dependent amplitudes. The first prototyping of a nanogenarator by means of ZnO piezoelectric nanowire (NW) arrays have demonstrated to able to drive sensor network nods in micro-power range. ZnO piezoelectric thin films have also been successfully transferred onto flexible substrates for stretchable energy harvesting, which suggests new possible applications of piezoelectric nanomaterials. However so far the fundamental mechanism from thin film piezoelectric generator is still unclear. To further clarify the effect of stress-induced and nonsymetry charge center promoted electrical potential is critical for large power output from ZnO nanogenerator. power output from NW nanogenarator is still in the power range micro watt, which is still far way from milli-power output source requested by most applications of individual sensor and sensor network system. The lacking of high power output in current ZnO NW generator is partially attribute to non-well c-axis oriented crystalline of ZnO NW material and low yield in NW device[5], both are synthesized by chemical method. Therefore to explore new approach for ZnO NW material synthesis to enhance piezoelectric effect is desirable. In this paper, the effects of the stress on piezoelectric response for ZnO film grown by pulsed-laser deposited (PLD) are investigated. To promote differerent film stress, the ZnO films are deposited at different thcknessa and different temperature. Structurally, special emphasis is placed on XRD characterizations of the films. Additional characterizations using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) will be detailed at a later date. The piezo-electric properties of these films are characterized by Piezoelectric Force Microscopy (PFM). The observed corresponds of piezoelectric (PE) property to stress is also theoretically investigated. *Corresponding author,

Authors : (1), (2) Pushkar N. Patil (1) Riccardo Checchetto (1) Roberto S. Brusa (1) Antonio Miotello
Affiliations : (1) Department of Physics, University of Trento, via Sommarive 14, I-38123, Povo, TN, Italy (2) Institute for Composites and Biomedical Materials, National Research Council, Piazzale Tecchio, 80, I-80125 Napoli, Italy

Resume : The development of polymeric membranes for gas separation is of increasing importance in areas such as carbon dioxide separation, dehydration, hydrogen capture/storage and oxygen-nitrogen separation as well as advanced functional material for gas sensing. Epoxy resins are one of the most important thermosetting polymers having wide applications in adhesives, mixed matrix membranes and separation sciences owing to their high strength, stiffness and good adhesion to many substrates. To achieve specific properties, uncured epoxy resins should be converted into crosslinked macromolecules having the correct crosslinking density. In the present study, a cured epoxy resin has been used as a polymeric membrane for the study of the gas transport process. The aliphatic epoxy is cured by diamines with various chain lengths to achieve different crosslink density of the polymeric membranes in order to obtain different free volume structure at nanoascale level. Characterization of them was done by FTIR and DSC while the gas transport was studied for light gases such as CO2, N2 and H2 gases at different temperatures by gas phase permeation technique. The gas transport parameters such as permeability, diffusivity and gas selectivity were evaluated and correlated with the free volume properties, as analyzed by Positron annihilation spectroscopy.

Authors : A.Taoufyq, F.Guinneton , J-C. Valmalette, A. Benlhachemi, B. Bakiz, A. Lyoussi, G. Nolibe, J.R. Gavarri
Affiliations : Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université de Toulon, BP 20132, 83957, La Garde Cedex, France. Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université de Toulon, BP 20132, 83957, La Garde Cedex, France. Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université de Toulon, BP 20132, 83957, La Garde Cedex, France. Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc. Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc. Département d‘Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA, 13108, Cadarache, France. Société CESIGMA- signals & systems, 1576 Chemin de La Planquette, 83130, La Garde, France. Institut Matériaux Microélectronique et Nanosciences de Provence, IM2NP, UMR CNRS 7334, Université de Toulon, BP 20132, 83957, La Garde Cedex, France.

Resume : To develop new sensing devices, we try to connect catalytic and photonic behaviors in materials susceptible to present at least two types of applications. The bismuth tungstate phase Bi2WO6 is a typical multifunctional material presenting several properties: piezoelectricity, ionic conduction, photocatalytic activity and luminescence under UV or X-ray excitation. Presently, we develop systematic studies on the series Bi2-xLnxWO6 where Ln is a rare earth (La, Lu, Ce). We analyze the evolutions of luminescence or photocatalytic activities with composition x, crystallinity and size effects. Polycrystalline samples and thin layers have been elaborated and characterized. The structures are constituted of (Bi2O2)2+ and (WO4)2- alternating layers involving a complex electron band structure. The photocatalytic activity is conditioned mainly by the band gap and the specific surface of the material. The luminescence responses are conditioned by additional specific energy levels associated with permitted transitions. The photocatalytic degradation of Rhodamine B in aqueous medium has been studied using polycrystalline phases Bi2-xLnxWO6 as catalysts subjected to irradiation by a Xenon lamp. The photocatalytic efficiency strongly depended on the elaboration conditions and more precisely on particle sizes. The photocatalytic responses are directly linked to electron transfer from the valence band to the conduction band and depend on the gap of the samples (close to 2.7 eV). This gap depends on the elaboration conditions. Luminescence analyses under UV or X-ray irradiation have been performed on the same samples and discussed. The luminescence responses in the case of UV or X-ray irradiation are probably due to additional energy levels in the band gap and cannot be easily interpreted. In the case of thin layers, the luminescence responses under UV irradiation have been observed and discussed.

Authors : C.Fabrega 1, A. M. Saranya 1, A. Morata 1, A. De Luca 2, S. Zeeshan 3 A. Tarancón 1, F. Udrea 2-3, J.R.Morante 1
Affiliations : 1. IREC, Catalonian Institute for Energy Research, Jardíns de les Dones de Negre,1. San Adrià del Besòs. 08930. Spain; 2. Cambridge University; 3. CMOS sensor

Resume : Easy detection of oxygen is of great interest from many different applications. However, the current oxygen solid state based sensor technology, mainly based on oxide ionic conductors such as doped zirconia, requires high operating temperatures that prevent from its integration in standard microplatform technologies. In this contribution, we present two new approaches that allow driving the technology towards feasible integrated oxygen gas sensors, namely, (i) using silicon on insulator based platforms from Cambridge CMos Sensors Ltd to allow increasing the operation temperature and working under pulsed mode and (ii) screening mixed ionic electronic conductor perovskite materials with different oxygen exchange properties (T<400ºC) as oxygen sensitive material. Lanthanum Strontium Cobaltite (LSC), Lanthanum Strontium Manganite (LSM) and Lanthanum Strontium Ferrite (LSF) have been deposited by pulsed laser deposition (PLD) on silicon on insulator (SOI) based microchips and their electrical and sensing properties have been fully characterized as conductimetric gas sensing device. Positive features and limitations of these approaches will be presented and discussed in relation to the current state of the art.

Authors : Oscar Olvera-Neria, Virineya Bertin, Enrique Poulain
Affiliations : 1 Area de Fisica Atomica Molecular Aplicada (FAMA), CBI, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, Mexico, D. F. 02200, Mexico. 2 Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Mexico, D. F. 09340, Mexico.

Resume : Nitrous oxide (N2O) is an undesired effect of the actions taken to control the emission of exhaust pipe gases produced by gasoline combustion. Thus, the catalytic conversion of N2O to N2 is a necessary step to accomplish the actual environmental legislation. The adsorption and dissociation of N2O catalyzed by the square-based pyramidal Rh5 cluster was investigated using the density functional theory and the zero order regular approximation (ZORA). The sextet ground state of Rh5 is the most active in N2O dissociation, though the quartet and octet states are also active because they are degenerate. The Rh5 cluster activates spontaneously the N2-O cleavage and the reaction is highly exothermic ca. -75 kcal/mol. The breaking of N2-O is obtained for the geometrical arrange that maximizes the overlap and electron transfers between the N2O and Rh5 frontier orbitals. The high catalytic activity of Rh5 is due to the Rh 3d orbitals being in the middle of the HOMO and LUMO orbitals of N2O, which makes possible the interactions between them. In particular, the O 2p states strongly interact with Rh 3d orbitals, which finally weakens the N2-O bond. The electron transfer is from HOMO orbital of Rh5 to the antibonding orbital of N2O.

Authors : V. H. Uc, J. C. Gonzalez, E. Poulain, O. Olvera-Neria, V. Bertin
Affiliations : Area de Fisica Atomica y Molecular Aplicada, Universidad Autonoma Metropolitana de Azcapotzalco. Av. San Pablo 180, Edificio HP. Col. Reynosa-Tamaulipas, Mexico D.F., C.P. 02200, Mexico. Departamento de Quimica, Universidad Autonoma Metropolitana de Iztapalapa. San Rafael Atlixco 186. Edificio R-216, Col. Vicentina. Mexico D.F., C.P. 09340, Mexico.

Resume : N2O is an intermediary product in the NO reduction with CO. The interaction of the N2O on Pdn (n = 1-6) nanoparticles were studied with the density functional theory (dft) in its triplet and quintuplet multiplicity states. We found that the Pdn nanoparticles with triplet multiplicity states, the N2O is only adsorbed, but in the case of the quintet multiplicity state, we found in that the Pd1, Pd2 and Pd3 nanoparticles the N2O is activated, breaking the N-O bond, and remaining the N2 and O attached to the Pdn nanoparticles, while in Pd4, Pd5 and Pd6 nanoparticles only the adsorption is presented.

18:30 Gathering of Day    
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Integration of Nanosensors for Scale-Up : Eduard Llobet, University Rovira i Virgili (Spain) and Albert Romano-Rodriguez, Universitat de Barcelona (Spain)
Authors : Michele Penza and EuNetAir Consortium (
Affiliations : ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development Technical Unit for Materials Technologies - Brindisi Research Center, PO Box 51 Br4; I-72100 Brindisi, ITALY

Resume : This is a overview of the COST Action TD1105 EuNetAir - European Network on New Sensing Technologies for Air-Pollution Control and Environmental Sustainability - funded in the COST framework. The objective of the Concerted Action (2012-16) is to develop new sensing technologies for Air Quality Control at multidisciplinary scale by coordinated research on nanomaterials, sensor-systems, air-quality modelling and standardised methods to support environmental sustainability with special focus on SMEs. This international Networking, coordinated by ENEA (Italy), includes over 80 institutions and over 170 international experts from 28 COST Countries (Austria, Belgium, Bulgaria, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Latvia, The Former Yugoslav Republic of Macedonia, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovenia, Spain, Sweden, Switzerland, Turkey, United Kingdom) and 7 Non-COST Countries (Australia, Canada, China, Morocco, Russia, Ukraine, USA) to create a S&T critical mass in the environmental issues. This COST Action focuses on a new detection paradigm based on sensing technologies at low cost for Air Quality Control and set up an interdisciplinary top-level network to define innovative approaches in sensor nanomaterials, gas sensors, devices, wireless sensor-systems, distributed computing, methods, models, standards and protocols for environmental sustainability within the European Research Area.

Authors : Martin W. G. Hoffmann (1,2,3), Olga Casals (1), Francisco Hernandez-Ramirez (1,3), Andreas Waag (2), Hao Shen (2), J. Daniel Prades (1)
Affiliations : 1) Department of Electronics, University of Barcelona, Barcelona, Spain 2) Institut f?r Halbleitertechnik, Technische Universit?t Braunschweig, Braunschweig, Germany 3) Department of Advanced Materials for Energy Applications, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

Resume : Low power consumption and high specificity are two of the most sought after requirements for future gas sensors technologies. In this contribution, new device concepts capable to detect gases without the need of external power sources to activate the sensor-gas interaction or to generate a read out signal will be described [1]. It will be demonstrated that sensors featuring zero power consumption can be achieved by integrating the sensing components and the energy sources intimately, at the nanoscale. On the other hand, a rational methodology to design organic surface functionalizations that provide high selectivity towards single gas species will also be discussed [2]. Specifically, theoretical results, confirmed experimentally, indicate that precisely tuning the sterical and electronic structure of the sensor material and the organic functionalization can lead to unprecedented selectivity values, comparable to those typical of bioselective processes. Finally, the first attempts to combine both strategies in one single, solid-state, cost-effective, integrated device will also be presented. [1] M. W. G. Hoffmann, A. E. Gad, J. D. Prades, F. Hernandez-Ramirez, R. Fiz, H. Shen, S. Mathur, Nano Energy 2013, 2, 514?522. [2] M. W. G. Hoffmann, J. D. Prades, L. Mayrhofer, F. Hernandez-Ramirez, T. T. J?rvi, M. Moseler, A. Waag, H. Shen, Adv. Funct. Mater. 2013, DOI: 10.1002/adfm.201301478

Authors : A. Koeck, S. Defregger, E. Kraker, S. Steimnhauer, T. Maier, G.C. Mutinati, K. Rohracher, J. Siegert, F. Schrank, E. Wachmann
Affiliations : Materials Center Leoben, AIT Austrian Institute of Technology, ams AG

Resume : The employment of metal oxide nanowires is a very powerful strategy to push the performance of gas sensing devices. Nanowires have a high surface to volume ratio and a strong interaction with the surrounding gas. Nanowire based sensors thus provide very sensitive gas detection and have the advantage of improved stability due to high crystallinity. However, efficient and reliable nanowire integration with standard CMOS technology remains a major challenge. We present gas sensor devices employing metal oxide nanowires integrated on micro hotplates devices, which are fabricated in standard 0.35µm CMOS technology combined with a MEMS etching process. Three different nanowire materials are employed for realization of the gas sensor devices: SnO2, CuO, and ZnO. The specific processes developed for the CuO and ZnO nanowires enable their direct synthesis on the CMOS micro hotplates; the SnO2 nanowires, however, require a transfer process from a specific synthesis wafer to the CMOS micro hotplates. The presented technologies can be used in a CMOS backend process and enable the fabrication of fully silicon integrated SnO2, CuO and ZnO nanowire gas sensing devices. The gas sensing performance of the nanowire based gas sensor devices to a variety of gases (CO, CO2, VOCs, H2, H2S) relevant for environmental monitoring will be presented. The approach towards a fully CMOS integrated multi-parameter gas sensing device will be discussed.

Authors : C.Fabrega 1, A. De Luca 2, S. Zeeshan 3, F. Udrea 2-3 J.R. Morante 1
Affiliations : 1. IREC, Catalonian Institute for Energy Research, Jardíns de les Dones de Negre,1. San Adrià del Besòs. 08930. Spain; 2. Cambridge University; 3. CMOS sensor

Resume : Metal oxides are a candidate for active material adequate for low -cost & high- mass-production of gas sensors. After many options, integrated sensor devices sensors based on silicon base platform become the more feasible and reliable technology only limited but the range of available temperature excursion although, nowadays, it can be overcome using SOI based platforms which could work up to 600ºC. Furthermore, this gas sensor configuration allows also working on pulsed operation mode instead the more traditional isothermal one. However, due to the small effective area of the platform, 200 microns diameter, one of the stronger drawbacks is the availability of techniques for such localized deposition of sensing material. Although different methods have already been proposed as inkjet, sputtering, localized CVD, etc. …they have some drawbacks concerning, respectively, to reproducibility, material stoichiometry control or strong requirement on ambient and platform conditions. In this contribution, the use of Pulsed Laser Deposition on SOI platforms is presented and discussed. Examples are taking on a referential SnO2 active layer which was successfully deposited. Deposition parameters, such as oxygen pressure, laser energy and thickness, were optimized for obtaining stable and porous layers which show the expected CO gas sensors charactersitics. Devices were characterized in both, steady and pulsed temperature modes as CO sensors showing a fully compatibility between PLD and SOI platforms.

10:00 Coffee Break    
Carbon Nanomaterials for Gas Detection : Rositza Yakimova, Linköping University and Graphensic AB (Sweden) and Gerardo Palazzo, University of Bari (Italy)
Authors : Jing Li
Affiliations : NASA Ames Research Center

Resume : Nanotechnology offers the ability to work at the molecular level, atom by atom, to create large structures with fundamentally new molecular organization. It is essentially concerned with materials, devices, and systems whose structures and components exhibit novel and significantly improved physical, chemical and biological properties, phenomena, and process control due to their nanoscale size. A nanosensor technology has been developed at NASA Ames using nanostructure, single walled carbon nanotubes (SWNTs), combined with silicon-based microfabrication and micromachining process. The nanosensors have achieved low detection limit of chemicals in the concentration range of ppm to ppb. More than 15 chemicals have been tested and differentiated. Due to large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors offer higher sensitivity, lower power consumption and a more robust solution than most state-of-the-art systems making them attractive for space and defense applications, as well as a variety of commercial applications. Leveraging the micromachining technology, the light weight and compact sensors can be fabricated, in wafer scale for mass production, with high yield and at low cost. An example of a sensor module, the first space flown nano device, will be introduced in this presentation. Such sensors have drawn attention from space community for global weather monitoring, space exploration, life search in the universe, and launch pad fuel leak detection and in-flight cabin air and life support system monitoring, and engine operation monitoring. Additionally, the wireless capability of such sensors can be leveraged to network mobile and fixed-base detection and warning systems for civilian population centers, military bases and battlefields, as well as other high-value or high-risk assets and areas in industry.

Authors : Elena Dilonardo 1, Michele Penza 2, Marco Alvisi 2, Domenico Suriano 2, Riccardo Rossi 2, Francesco Palmisano 1, Luisa Torsi 1, Nicola Cioffi 1
Affiliations : 1 Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Campus Universitario, via Orabona 4, 70126 Bari, Italy. 2 ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development Technical Unit for Materials Technologies - Brindisi Research Center, PO Box 51 Br4; I-72100 Brindisi – Italy.

Resume : In the present study, Au-surfactant core-shell colloidal nanoparticles (Au NPs) with controlled dimension and composition were synthesized by sacrificial anode electrolysis. Transmission electron microscopy revealed that Au NPs core diameter is comprised between 8-12 nm, as a function of the electrosynthesis conditions; UV-vis spectroscopy showed that size effects affect position and width of the surface plasmon resonance peak. Moreover, surface spectroscopic characterization by XPS analysis confirmed the presence of nanosized gold phase. Controlled amounts of Au NPs were then deposited electrophoretically on CNTs networked films. The resulting hybrid materials were morphologically and chemically characterized using TEM, SEM and XPS analyses, which revealed the presence of nanoscale gold, and its successful deposition/decoration on CNTs. Au NPs/CNTs networked films were tested as active layers in a two-pole resistive NO2 sensor for sub-ppm detection. Au-NPs/CNTs exhibited a p-type response with a decrease in electrical resistance upon exposure to oxidizing NO2 gas and an increase in resistance upon exposure to reducing gases (e.g., CO, SO2). It was also demonstrated that the sensitivity of Au NP/CNTs-based sensors depends on Au-loading; therefore the impact of Au loading on gas sensing performance was investigated as a function of the working temperature, gas concentration and interfering gases.

Authors : A. K. Boyd, I. Dube, G. Fedorov, M. Paranjape, and P. Barbara
Affiliations : Georgetown University, Washington DC, USA; RRC Kurchatov Institute, Moscow, 123182, Russia

Resume : We investigate the sensing mechanism of carbon nanotube chemiresistors. The two possible mechanisms emerging from many theoretical and experimental works are: 1) adsorption of gas molecules on the nanotube surface, or 2) changes of the Schottky barriers at the carbon-nanotube/electrode interface, due to a modulation of the electrode work function in the presence of gases. We use a contact passivation method and selective exposure of the nanotubes to the gas [1] to identify the detection mechanism of carbon nanotube networks, by also varying the density of nanotubes and nanotube-nanotube junctions. We find that NO2 adsorption at the nanotube-nanotube junctions causes a change in resistance of these junctions, thereby contributing to the sensor response, in addition to the contribution from the nanotube-electrode interfaces. Effects of gas adsorption in regions of the nanotubes away from the nanotube-nanotube junctions could not be detected, in agreement with the results from single-nanotube devices, where there are no junctions and only the nanotube/electrode contacts contribute to the response [1, 2]. These results clearly bring into focus the importance of nanotube-nanotube junctions for the sensing mechanism, thereby paving the way toward future experimental and theoretical work to understand how gas adsorbed on the junctions formed by carbon nanotubes changes their conductance. [1] J. Zhang et al., Appl. Phys. Lett. 88, 123112 (2006). [2] A. K. Boyd et. al., Carbon, in press.

Authors : K. Chikkadi, M. Muoth, M. Haluska, C. Roman, C. Hierold
Affiliations : Micro and Nanosystems, ETH Zurich, Switzerland

Resume : Sensing mechanisms of SWNT-based NO2 sensors are heavily debated, as the roles of the metal contact, neighboring dielectric and the nanotube itself are unclear. Sensor response is often influenced by the presence of substrates, inter nanotube contacts and process residues which are very difficult to model theoretically. There are several competing models of NO2 adsorption mechanisms on the nanotubes, with no consensus on the precise nature of the adsorption. An experimental model system which can conclusively demonstrate the effect of NO2 adsorption on a single, isolated nanotube is therefore of great interest. Here, we present a device architecture which incorporates a suspended single, clean SWNT using a mechanical fork transfer process with passivated Pd source and drain contacts. This process simultaneously eliminates adsorption processes associated with the substrate, contact metal as well as process residues, leaving only the nanotube as the active component in the sensor. Exposure of the transistor to NO2 shows a clear change in the device conductance behavior. For the first time we can unambiguously associate this response with adsorption on a single nanotube. The NO2 concentration dependence follows a Langmuir isotherm, suggesting that the sensor response is proportional to the coverage on the nanotube surface. Transient measurements allow us to extract rise and fall times which can be related to the NO2 adsorption kinetics on the surface of a single SWNT.

Authors : S. Baldo, V. Scuderi, L. Tripodi, A. La Magna, S. G. Leonardi, N. Donato, G. Neri, L. Romano, S. Scalese
Affiliations : Istituto per la Microelettronica e Microsistemi, CNR, Catania, VIII Strada 5, 95121 Catania (Italy); Dipartimento di Ingegneria Elettronica, Chimica e Ingegneria Industriale, Università di Messina, Contrada di Dio, Salita Sperone 31, Messina (Italy); Dipartimento di Fisica ed Astronomia, Università di Catania, via S. Sofia, 95125 Catania (Italy);

Resume : In this work we report about the development of CNTFET back-gated transducers, with Carbon Nanotubes (CNT) layers playing the role of the channel, and their electrical characterization for sensing applications. The CNTs deposition was performed by electrophoresis on an interdigitated electrode region created on a SiO2/Si substrate. Different kinds of CNTs have been used (MWCNTs by arc discharge in liquid nitrogen, MWCNTs by CVD and SWCNTs) and the electrical characterization of the devices was performed in NH3 and NO2 controlled environment. Preliminary data have shown an increasing of the channel resistance after addition of NH3, whereas during the exposure to NO2 a decrease in the channel resistance was noted. Anyway, different kinds of CNTs show different sensitivities to the two gas environments. Furthermore, the formation of defects by ion implantation on CNTs was investigated by high resolution TEM. Raman analysis showed an increase of ID/IG ratio related to an increase of structural disorder, as expected. The observed behaviour of the devices can be explained in terms of the interaction between structural or chemical defects in CNTs and the gas molecules.

Authors : Jérôme BRUNET (1,2), Alain PAULY(1,2), Amadou NDIAYE(1,2), Christelle VARENNE(1,2), Abhishek KUMAR(1,2),Marc DUBOIS(3,4)
Affiliations : 1. Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand, France; 2. CNRS, UMR 6602, Institut Pascal, F-63171 Aubière, France; 3. Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France; 4. CNRS, UMR 6002, Institut de Chimie de Clermont-Ferrand, F-63177 Aubière, France.

Resume : The exponential development of nanomaterials opened the way to a new generation of devices with enhanced performances and new application fields. Among these new materials, nanocarbons are extensively investigated for the elaboration of electronic components like transistors, LEDs, electron sources and gas sensors. Since nanocarbonaceous materials offers high affinity with gases as exploited into sensing devices, we propose as complementary approach to shape nanocarbons as chemical filter for air cleaning. A large panel of pristine nanocarbons has been firstly studied: single and multi-wall nanotubes, nanowires, nanodiscs, activated carbons. Their filtering power, the interaction mechanisms involved with the target gases (O3, NO2, CO) as well as the physical and chemical properties of nanocarbons responsible for their filtering ability have been determined both from gas exposures and characterizations (EPR, Raman spectroscopy, NEXAFS). The relevance of original indigo/nanocarbons hybrid materials as O3 filter has been established too. The non-covalent functionalization of nanocarbonaceous materials by two wet chemical routes has been monitored by SEM, XRD and TGA. Performances like filtering efficiency, selectivity and sustainability have been especially assessed. As an application, we will discuss on the successful development of selective NO2 sensor-systems associating such a filter to phthalocyanine-based chemoresistor for the NO2 monitoring in ppb-range in air.

12:30 Lunch    
Modeling of Sensors and Sensor/Gas Interaction : Anita Lloyd Spetz Linköping University (Sweden) and University of Oulu (Finland) and Juan Ramon Morante, IREC and Universitat de Barcelona (Spain)
Authors : N. Abdelmalek, F. Djeffal, T. Bentrcia and M. Meguellati
Affiliations : LEA, Department of Electronics, University of Batna, Batna 05000, Algeria. E-mail:,, Tel/Fax: 0021333805494

Resume : The Gate All Around GAA MOSFETs have emerged as excellent devices to provide the electrostatic integrity needed to scale down transistors to minimal channel lengths, and allowing a continuous progress in digital and analog applications. Employing this design for chemical and environment monitoring applications becomes more beneficial if the device is made in vertical cylindrical recrystallized silicon due to highly flexible process integration options. In this paper, a numerical investigation of a new pH-ISFET design, called the Junctionless Gate All Around Ion-sensitive field-effect transistor with oxide kernel (pH-JGAAISFET), is proposed, investigated and expected to improve the fabrication process and the sensitivity behavior for pH-ISFET sensor-based applications. The numerical investigation has been used to propose a new sensitivity performance and predict the device behavior. The comparison of device architectures shows that the proposed sensor exhibits a superior performance with respect to the conventional ISFET in term of electrical performances. The obtained results make the proposed sensor a promising candidate for low cost monitoring and high performance pH sensing applications.

Authors : Luz Maria Garcia-Cruz, Julio Cesar Gonzalez Torres, Enrique Poulain, Oscar Olvera-Neria
Affiliations : Area de Fisica Atomica Molecular Aplicada (FAMA), CBI, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, Mexico, D. F. 02200, Mexico.

Resume : The oxidation reaction of carbon monoxide (CO) is a crucial step during the treatment of exhaust pipe gases produced by gasoline combustion. However, to obtain CO2, the O2 molecule must be dissociated before to yield atomic oxygen and the reaction CO O -> CO2 proceeds. We present the capture and activation of O2 by small Pd clusters and the subsequent oxidation of CO using the density functional theory (DFT) and the zero order regular approximation (ZORA). For Pd2 to Pd6 the ground state is the triplet, although for Pd3 and Pd6 the triplet state is degenerate with the singlet state. The dissociation of O2 presents a barrier, which depends on the size of the Pd cluster, for instance, the barrier for Pd2 is 24.64 kcal/mol, whereas for Pd4 is 33.65 kcal/mol. Thus, the activation barrier changes from 119 to ~33 kcal/mol when the catalyst is used. The O2 activation is the limiting step, because the interaction between CO and the atomic oxygen is spontaneous and highly exothermic, that is, the released energy for CO oxidation catalyzed by Pd3 is -45.68 kcal/mol and for Pd4 is -66.18 kcal/mol. The bond order of O-O changes from 2.0 to 1.31 when the oxygen molecule is adsorbed, which favors the dissociation. Furthermore, the CO in gas phase reacts directly with the adsorbed atomic oxygen, which differs from the Langmuir-Hinshelwood mechanism, where both reactants must be adsorbed. The dissociation is due to electron transfer from Pd clusters to the antibonding orbital of O2 adsorbed.

Authors : Massimiliano D'Arienzo, Lidia Armelao, Claudio Maria Mari, Riccardo Ruffo, Roberto Scotti, Franca Morazzoni
Affiliations : University of Milano Bicocca

Resume : The unique properties of SnO2 and WO3 nanocrystals which expose specific surfaces as chemical sensors have been recently reported. However, a clear assessment of the relative involvement of the crystal faces in the sensing mechanism is still under debate. To clarify this issue, we have carefully investigated the sensing behavior of SnO2 shape controlled nanoparticles in connection to the generation and the reactivity of their oxygen defects (VO•), detected by ESR, associating their abundance and reactivity to the exposed crystal faces and to the electrical response of the nanocrystals. Results indicate that the presence of the {221} and {111} surfaces enhances the generation of the VO• centers and boosts the sensing performance toward CO. A similar investigation was carried out on WO3 nanocrystals with tailored morphology and definite prominent surfaces. Their sensing performances toward NH3 were evaluated and, in order to deepen the role of the surfaces in the sensing mechanism, a comprehensive XPS investigation on the surface nitrogen species was also performed. It turned out that {020} and {002} high-energy surfaces represent privileged reactive sites for the NH3 oxidation and therefore are essential for enhancing the sensing properties. These outcomes may help to a more effective evaluation of the involvement of the crystal surfaces in the sensing mechanism and may shed some light on how crystal facet engineering can be better applied to design more efficient gas sensors.

Authors : Konstanze Hahn, Antonio Tricoli, Alfons Baiker
Affiliations : Department of Pysics, University of Cagliari; College of Engineering and Computer Science, Australian National University; Department of Chemistry and Applied Biosciences, ETH Zürich

Resume : The semiconducting nature of many metal oxides makes them interesting materials for numerous industrially and economically important applications. Wide band gap metal oxides such as SnO2 and TiO2 are used, for example, in solar cells or photocatalysis. Moreover, their ability to change conductivity when gaseous molecules are reacting with the surface makes them particularly applicable for chemoresistive portable gas sensors. A main drawback of metal oxide materials both in photocatalysis and as gas sensors, however, is the reaction of their surfaces with water vapor. In other words, changes in the relative humidity of the environment can significantly influence the performance of the metal oxide. This is one of the major shortcomings of SnO2-based gas sensors used, for example, in breath analysis. Experimentally, it has been shown that this can be overcome by doping of SnO2 with other metal atoms, such as Ti. In this project, density functional theory calculations have been utilized to simulate the formation of SnO2-TiO2 solid solutions demonstrating favorable distribution of Ti on the SnO2 surface. The introduction of Ti atoms on sixfold surface sites leads to a destabilization of H2O species adsorbed dissociatively on the SnO2-TiO2 surface. An overall minimum in the absolute value of H2O binding energy has been found at 25-30% surface Ti content. This gives a possible explanation for the minimum in cross-sensitivity to humidity found experimentally for Ti-doped particles.

Authors : Pawel Kempisty, Stanislaw Krukowski, Pawel Strąk
Affiliations : Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland

Resume : Using density functional theory (DFT) calculations we analyzed interaction of gas phase components with the GaN(0001) surfaces. A slab model was used to simulate the adsorption and desorption processes of hydrogen and ammonia in a function of surface coverage and the doping of the semiconductor bulk (n, p or semiinsulating). It was found that the adsorption energy of atoms or molecules depends strongly on the relative fraction of surface coverage. We observed that the adsorption is strongly dependent on the availability of empty states at the surfaces and pinning of the Fermi level at the surface. If the quantum states at the semiconductor surface strongly pin the Fermi level, the doping type of the semiconductor bulk has negligible impact on the process, the adsorption/desorption energy is approximately the same for the n-type and p-type, similarly to that observed for metal surfaces. A completely different behavior is observed when the surface comply with the electron counting rule (ECR) so that Fermi level is determined by the dominating point defect states in the bulk. Under such conditions, the adsorption energy may have a different value depending on whether the material is p-type or n-type. It is crucial that the process involves the charge transfer as in the case of open shell systems like metal atoms or the dissociating molecules. Presented phenomenon may be important in the context of gas/surface interaction for practical applications in the field of gas sensing.

Authors : Felipe Murphy-Armando
Affiliations : Tyndall National Institute, University College Cork, Ireland

Resume : The resistivity and lattice constant of Pd are very sensitive to the concentration of absorbed hydrogen in its lattice. These properties make Pd a promising H sensor[1]. However, until recently, the carrier scattering mechanisms in this material have not been well understood. In this work, we extend earlier first-principles electronic structure theory methods[2,3] to calculate the change in the resistance of Pd due to H absorption. We use density functional theory and density functional perturbation theory to obtain the carrier-hydrogen and carrier-phonon scattering rates across the whole Fermi surface. We then use the Boltzmann transport equation in the relaxation time approximation to compute the electrical resistivity vs. absorbed H concentration. We find very good agreement to experiment. [1] F. Favier, E.C. Walter, M.P. Zach, T. Benter and R.M. Penner, Science, 293, 2227 (2001). [2] F. Murphy-Armando and S. Fahy, Phys. Rev. Lett., 97, 096606 (2006). [3] F. Murphy-Armando and S. Fahy, Phys. Rev. B 78, 035202 (2008).

15:30 Coffee Break    
Hybrid and Composite Materials for Bio- and Chemical Sensing : Shanqing Zhang, Griffith University (Australia) and Michele Penza, ENEA (Italy)
Authors : Maria Magliulo1, Antonia Mallardi2, Kyriaki Manoli1, Nicola Cioffi1, Gerardo Palazzo1 and Luisa Torsi1
Affiliations : 1 Department of Chemistry, University of Bari, Via Orabona, 4, I-70126 Bari, Italy. 2 Istituto per i Processi Chimico-Fisici (IPCF), CNR – Via Orabona, 4, I-70126 Bari, Italy

Resume : Innovative organic field effect transistors (OFETs) realized through the full integration in the electronic device of purple membranes containing the protein bacteriorhodopsin (bR) will be presented. The bR is a light-driven ion pump whose biological activity is explicated by protons driven across the bacterial membrane as photons are absorbed. Associated to this process conformational changes of the protein occur. The response of the OFETs depends on the properties of the integrated bR membrane protein and thus opens a new way of probing the events involving proteins conformational changes. Purple membranes containing bR are known to be sensitive to anesthetics. The opportunity to study these key relevant interfacial interactions and possibly contribute to shed light on the general anesthesia action mechanism was the driving force to choose volatile general anesthetics as external stimuli for bR integrating OFETs. Specifically, anesthetics are capable to modify the bR local pKa values causing membrane protein changes that are easily probed by measuring the OFET electrical response. Such devices can act as selective anaesthetic sensors allowing label-free detection and operate at low reagent and power consumption and can be readily miniaturized and automatized in portable and disposable devices. The responses to anesthetics obtained with bR integrating OFETs will be discussed and it will be shown how the results of the present study challenges the anesthetic mechanisms model relying on the so far provided evidence that clinically relevant doses do not alter lipid bilayers overall-structure, significantly. References M.D. Angione, et al PNAS 109 (17), 2012, pp 6429-6434. M.D. Angione et al Biosens Bioelectron 40, 2013, pp 303-307.

Authors : T M?rian1,2, N.Redon1,2, Z. Zujovic3, D. Stanisavljev4, JL Wojkiewicz1,2, M. Gizdavic-Nikolaidis3,4
Affiliations : 1 Univ Lille Nord de France, F59000 Lille, France 2Mines-Douai, CE, F-59508 Douai, France 3School of Chemical Sciences, the University of Auckland, Private Bag 92019, Auckland 1142, New Zealand 4 Faculty of Physical Chemistry, Studentski trg 12-16, 11001 Belgrade, University of Belgrade, Serbia

Resume : Ammonia and amines can originate from both various human initiated sources including animal husbandry, industry and combustion, composting operation, automobiles, cooking, tobacco smoke, and natural sources as biomass burning, and biodegradation of organic matter that contain proteins or amino acids. The adverse health effects of amines and ammonia are demonstrated and it is important to detect them for health and environment protection. Due to base properties of ammonia and amines, conducting polyaniline (PANI) can be used to create inexpensive gas sensors with a very low quantification limit and relatively short response time. The principle of measurement is based on the electrical variation of the resistance of an active layer submitted to the gas. Following this principle, we developed a new low cost organic electronic sensor with PANI composites to detect ammonia and trimethylamine at room temperature. Two types of nanocomposite materials were synthesized and optimized for gas detection at ppb levels. First a PANI doped with a sulfonic acid/ polyurethane composite was studied for ammonia detection. It was demonstrated that the percolation phenomena and the rate of doping can be used to enhance the response of the sensors at ppb levels. Second PANI nanofibers synthesized by microwave treatment were used for trimethylamine detection. It was shown that the use of percolation phenomena added to this particular nanostructure can make sensors with large response at ppb levels. In both cases, it is demonstrated that nanostructured conducting polymers are suitable for new generation of nanosensors for air quality control.

Authors : Niina Halonen 1), Timir Datta-Chaudhuri 2)3), Antti Hassinen 4), Somashekar B. Prakash 3)5), Peter Möller 6), Pamela Abshire 3), Elisabeth Smela 2), Sakari Kellokumpu 4) and Anita Lloyd Spetz 1)6)
Affiliations : 1) Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering, University of Oulu, P.O. Box 4500, FI-90014 University of Oulu, Finland; 2) Laboratory for MicroTechnologies, Department of Mechanical Engineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA; 3) Integrated Biomorphic Information System Laboratory, Department of Electrical & Computer Engineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA; 4) Division of Cell Biology, Department of Biochemistry, University of Oulu, P.O. Box 3000, FI-90014 University of Oulu, Finland; 5) Advanced Design Organization, Intel Corporation, Hillsboro, Oregon USA; 6) Division of Applied Sensor Science, Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping, Sweden

Resume : Nanomaterials have an increasing number of uses in electronic, automotive, cosmetic, and medical applications. However, the interaction of a nanomaterial with biological systems may differ significantly from its bulk counterpart. The health effects of nanomaterials are generally evaluated using cytotoxicity assays and animal testing, the latter posing ethical issues. Here we introduce the use of IC chips designed for charge-based capacitance measurements of cells to evaluate the cytotoxicity of nanoparticles. Adherent cells normally spread out and attach to the surface on which they are cultured, but stressed cells “ball up” and finally come loose as they become non-viable. The changes in morphology and attachment can be monitored via a change in capacitance. The IC chips were produced in a commercially available CMOS technology and the chips consisted of capacitance sensor arrays and readout circuitry. The sensors were fully differential to increase dynamic range and suppress noise. The technology was tested with nanosized TiO2 materials, which have been reported to be cytotoxic. Adherent kidney cells of Cercopithecus aethiops were cultured on the surface of the sensor chip and exposed to nanoparticles after confluency was achieved, and the cell viability after exposure was evaluated with both the CMOS chip and a commercial cytotoxicity kits. Preliminary results indicate that cell viability can be monitored by capacitance measurements.

Authors : Sebastian Pregl, Felix Zoergiebel, Lotta Roemhildt, Larysa Baraban, Walter M. Weber, Thomas Mikolajick, and Gianaurelio Cuniberti
Affiliations : Technische Universität Dresden, Faculty of Mechanical Science and Engineering, Institute for Materials Science, Materials Science and Nanotechnology Team, Hallwachsstrasse 3, 01069 Dresden, Germany

Resume : After the years of intense investigations, nanomaterials have entered the phase of commercial applications in medicine as drug carriers or labels contrast agents for magnetic resonance imaging, and convenient tool for biodetection. Prominent example is the use of nanoparticles in combination with fluorescent labels for large number of biochemical tests. During last decade a new class of biological sensors emerged, which relies on the use of nanomaterials i.e. nanoparticles or nanowires, for detection of biological molecules or of products of biologically catalyzed reactions. Within this novel group of the devices, silicon nanowire based field effect transistors represent a promising route for label-free detection of biochemical species. Here we present and fully characterize the biosensor platform based on NiSi2-Si-NiSi2 nanowire heterostructures. Such devices require integration of Schottky-barriers (SB) to provide the change in contact resistance, which can be further used for sensing. We focus on the following aspects of the biosensor functioning and characterization: (i) fabrication and characterization of the SB-FET nanodevices; (ii) biochemical functionalization of the silicon nanowire sensors using aptamers, also known as “artificial antibodies”; (iii) demonstrate sensing capabilities of the developed devices.

Authors : Ying-Shuo Chiu, Ching-Ting Lee
Affiliations : Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University 701, Tainan, Taiwan, Republic of China

Resume : Recently, the diabetes mellitus have caused serious impact on the health of human beings. To effectively monitor the glucose concentration in human serum is an essential issue for the biomedical field. The extended-gate field-effect-transistors (EGFETs) been widely developed as the biosensors due to the inherent merits including easier fabrication and disposable sensing electrode. However, the longer signal passing distance and the larger dimension of the devices should be further improved. To overcome the drawbacks, a novel ion-selective field-effect-transistor (ISFET), integrating the ZnO-based field-effect-transistor and ZnO nanorod sensing membrane, was fabricated as glucose biosensor by a unique vapor cooling condensation system. This system can lead the interface of layers avoid contaminating in fabrication process. In addition, a photoelectrochemical (PEC) method was used to passivate the dangling bonds and the surface states resided on the surface of ZnO nanorods. The existence of them would induce the Fermi level pinning effect and degrade the resulting sensing performances. The integrated ZnO nanorod-based ISFET glucose biosensors with PEC passivation exhibited a favorable sensing sensitivity of 24.45 uA/mM. Moreover, the apparent Michaelis–Menten constant of the glucose biosensors was also improved to 6.95 mM. This promising integrated structure of the biosensors and the PEC passivation function are useful for developing the biomedical manufacture in the future.

Authors : Rob van Schaijk, Peter Offermans
Affiliations : imec/Holst Centre High Tech Campus 31, Eindhoven, the Netherlands

Resume : There is a high demand for environmental monitoring devices, which combine sensitivity and selectivity with compactness, portability and low cost. We develop sensors meeting these criteria based on AlGaN/GaN hetero junctions. Recent developments in the growth of epitaxial III-nitride layers on Si(111) substrates (8”) allow for large scale production of devices with a highly mobile two dimensional electron gas (2DEG) formed at the interface between GaN and AlGaN. The sensitivity of these open gate devices can be tuned to the low-ppb range by precise recessing of the AlGaN sensitive area [1]. This allows, for example, the detection of NO2 at the low-ppb level. The NO2 sensing mechanism of recessed AlGaN/GaN hetero-structures is attributed to the interaction of NO2 with surface donor states. NO2 is a major air pollutant that is subject to environmental regulation. To cover large areas the development of a low-cost environmental micro sensor that can be operated in a network is of high interest. The response and recovery of the sensor can be accelerated by slope detection and heating. This speeds up the response time from 30 minutes to tens of seconds. For this purpose membranes are formed by DRIE etching of the silicon substrate, to minimize power consumption of the sensor during heating . We will show progress on process development of GaN sensor on 8” Si wafers for NOx sensing, together with results of a field trial in a tunnel. Further development of this platform for different gases is in progress by functionalization of the AlGaN surface. [1] R. Vitushinsky, M. Crego-Calama, S. H. Brongersma, and P. Offermans, Appl. Phys. Lett. 102, 172101 (2013).

Authors : Maria Losurdo, Tong-Ho Kim, Maria M. Giangregorio, Giovanni Bruno and April S. Brown
Affiliations : 1 Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona 4, 70126 Bari, Italy 2 Electrical Computer Engineering Department, Duke University, 27708 Durham, North Carolina, US

Resume : The investigation of semiconductor and metal nanoparticle (NP) sensitization using organic dyes tailored new sensing functionalities is a very active area of research due to the need for efficient, environmentally-friendly, and economically-viable sensors able to operate in extreme conditions. The versatile functions presented by metalloporphyrins make these molecules the first choice for incorporation into new assemblies as active components. In this contribution, we present nitric oxide (NO) gas sensors based on high-temperature tolerant, high-mobility GaN and SiC semiconductors functionalized with hemin. A van der Pauw (VDP) resistivity sensor platform is used to explore the merits of using the SiC, GaN, and GaN/AlGaN materials systems for the detection of NO with a focus on device sensitivity and selectivity. The electrical behaviour is studied in terms of the GaN- and SiC- hemin interfacial chemistry illuminated through a surface/interfacial optical study using spectroscopic ellipsometry. The properties in relation to chemisorption kinetics are correlated with nitric oxide sensing performance. Our analysis includes the impact of GaN and SiC surface treatments (wet etching and plasma activation) on hemin layer formation, the temperature stability of the hybrid sensors, and the impact of semiconductor characteristics (bandgap, mobility, and carrier concentration) on the hemin functionalization thickness and aggregation, which affect final NO sensing performance. A comparison of performance in terms of selectivity and sensitivity with devices fabricated using the lower bandgap semiconductors, GaAs and InAs, is also presented.

Authors : M. Bouvet1, T. Sizun1, J.-M. Suisse1, T. Patois2, and B. Lakard2
Affiliations : 1: Institut de Chimie Moléculaire de l'Université de Bourgogne, Dijon, FRANCE 2: UTINAM, Besançon, FRANCE

Resume : Hybrid materials combining polypyrrole (PPy) with ionic macrocycles as counterions have been electrosynthesized at the surface of platinum interdigited electrodes. The obtained films revealed to be more homogeneous compared to PPy synthesized with small counterions, with a strongly smaller roughness. The films exhibited a higher sensitivity to ammonia (NH3), with a very good reversibility and with a stable response in a broad range of relative humidity (20-80 % RH). Overall, we present the advantages of combining ionic phthalocyanines (Pc) with PPy in enhancing the properties of the final material. Synergetic effects in the structure and properties of PPy-Pc materials open the way to their development in the field of hybrid material and their use for chemosensing. At a given RH value, the current baseline is very stable, the response to NH3 is highly reproducible, and proportional to the NH3 concentration. As a function of the RH, the relative response varies differently depending on the NH3 concentration. It increases, at 25 ppm, but increases then decreases at 45 and 90 ppm. However, at these NH3 levels, discrimination still occurs between the different concentrations. This result is very important, since it means that, whatever the RH in the range 20-80%, the device is capable to discriminate between these different NH3 concentrations.

18:30 Gathering of Day    
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Graphene Chemical Sensors II : Krishna C. Persaud, The University of Manchester (UK) and Ruth Pearce, National Physics Laboratory (UK)
Authors : Yung Yu Wang?, Ted D. Pham??, Katayoun Zand?, and Peter J. Burke?
Affiliations : ?Department of Chemical Engineering and Materials Science, ??Department of Biomedical Engineering, and ?Department of Electrical Engineering and Computer Science, University of California, Irvine, Irvine, California 92697, United States.

Resume : The interaction of cell and organelle membranes (lipid bilayers) with nanoelectronics can enable new technologies to sense and measure electrophysiology in qualitatively new ways. To date, a variety of sensing devices have been demonstrated to measure membrane currents through macroscopic numbers of ion channels. However, nanoelectronic based sensing of single ion channel currents has been a challenge. Here, we report graphene-based field-effect transistors combined with supported lipid bilayers as a platform for measuring, for the first time, individual ion channel activity. We show that the supported lipid bilayers uniformly coat the single layer graphene surface, acting as a biomimetic barrier that insulates (both electrically and chemically) the graphene from the electrolyte environment. Upon introduction of pore-forming membrane proteins such as alamethicin and gramicidin A, current pulses are observed through the lipid bilayers from the graphene to the electrolyte, which charge the quantum capacitance of the graphene. This approach combines nanotechnology with electrophysiology to demonstrate qualitatively new ways of measuring ion channel currents.

Authors : Di-Yan Wang,1 Tsung-Rong Kuo,1 Chun-Wei Chen,2 Yuh-Lin Wang,1 Cho-Chun Hu,3 Chia-Chun Chen.1,4
Affiliations : 1 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan 2Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan 3Department of Applied Science, National Taitung University, Taitung 95002, Taiwan 4 Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan

Resume : In this study, we have developed a novel layer-by-layer (LBL) structure matrix based on reduced graphene sheet (rGO) and gold nanoparticles (Au NPs) for enhancing surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) analysis. It is well known that rGO sheets (two dimensional atomic layers of sp2-bonded carbon) are predicted to have unique properties, such as large thermal conductivity, superior mechanical properties and excellent electronic transport properties. By simply one-step deposition of analytes onto the substrate of LBL rGO/Au, the MS measurements of various homogeneous samples are ready to execute. The small molecules including amino acid, carbohydrates and peptides are expected to be analyzed in SALDI-TOF MS using the LBL rGO/Au substrate. The signal contamination, S/N ratio and reproducibility of SALDI-TOF spectra can be improved in comparison to the traditional assisted matrixs (gold nanoparticles or α-cyano-4-hydroxy-cinnamic acid). We found that MS substrate, which allowed to absorb and transfer laser energy quite efficiently and homogenously, is ready-to-use to provide commercial potentials for MS applications.

Authors : Amer Al-Nafiey, Palaniappan Subramanian, Ahmed Addad, Sabine Szunerits, Brigitte Sieber, Rabah Boukherroub
Affiliations : Institut de Recherche Interdisciplinaire (IRI, USR CNRS 3078), Université Lille 1;Unité des Matériaux Et Transformations (UMET, UMR 8207), Université Lille1

Resume : Abstract The reduction of graphene oxide (GO) has been a subject of intense efforts in the last decade. Many efforts have been devoted to the preparation of chemically modified GO and graphene composites aiming at a better processability of graphene and modulating at wish its electronic, optical properties and electrochemical properties.1 Functionalization of graphene enables indeed this material to be processed by solvent-assisted techniques and prevents its agglomeration and thus maintaining the inherent properties of graphene crucially important for their end application. Reduced graphene oxide (rGO) is prepared through the reduction of GO using different means. The technique consists of the initial oxidation of graphite to graphite oxide, followed by the subsequent mechanical/chemical or thermal exfoliation of graphite oxide to graphene oxide (GO) sheets, and their reduction to graphene.2 Various approaches have been investigated for the reduction or reduction/functionalization of GO using chemical, electrochemical, thermal or photochemical means.2 Hydrazine monohydrate is still the most widely used reductant, mainly due to its strong reduction activity to eliminate most oxygen-containing functional groups of GO and its ability to yield stable rGO aqueous dispersions. However, with hydrazine as the reducing agent, its residual trace may strongly decrease the performance of rGO-based devices. In addition, hydrazine is a highly toxic and potentially explosive chemical. To avoid using hydrazine, many environmentally friendly and high-efficient reductants have been developed and used for the reduction of GO, including vitamin C, amino acids, reducing sugars, alcohols, hydroiodic acid, reducing metal powder, sodium citrate, tea, lysozyme, dopamine, etc.3 Herein, we report on simultaneous reduction/functionalization of graphene oxide (GO) using environmentally friendly reagent, arginine (Arg). This one-step reaction consists of a simple reaction of GO with Arg at 100°C for 4 h. Furthermore, this approach was successfully applied for the synthesis of rGO decorated with metal nanoparticles. The resulting materials have been characterized using UV-vis spectrometry, FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements. Finally, the catalytic activity of rGO/metal nanoparticles has been evaluated for the reduction of nitrophenol to aminophenol.

Authors : Jens Eriksson1, Donatella Puglisi1, Hossein Fashandi1, Mike Anderson1, Rositza Yakimova1-2, Anita Lloyd Spetz1
Affiliations : 1 Department of Physics, Chemistry, and Biology, Linköping University, 58183, Sweden; 2 Graphensic AB, SE-58333 Linköping, Sweden

Resume : Graphene-based gas sensors normally show ultra-high sensitivity to certain gas molecules while suffering from poor selectivity and slow response and recovery. Graphene functionalization can improve these issues but usually results in poor reproducibility. We report on surface modifications of epitaxial graphene on SiC with metal or metal-oxide nanostructures, formed by highly reproducible thin film deposition techniques, and their effect on the electronic properties of the graphene and on gas interactions at the graphene surface. Under the right decoration conditions the electronic properties of the surface remain those of graphene, while the surface chemistry can be modified to improve sensitivity, selectivity and speed of response toward e.g. nitrogen dioxide (NO2) or certain toxic volatile organic compounds (VOCs). Sensors with extremely low detection limits, selective towards these gases, can be useful for air quality control due to the high toxicity already at parts per billion (ppb) concentrations. The effect of decoration strongly depends on the choice, thickness and nanostructure of the material. Decoration with thin nano-porous Au allows reaching a NO2 detection limit below 1 ppb. Preliminary results indicate that decoration with TiO2 quantum dots can be used to selectively detect ppb concentrations of certain toxic VOCs. The presentation will include early results on other monolayer modifications of gas sensing layers like iron oxide on top of platinum.

10:00 Coffee Break    
Nanomaterials and Nanotechnologies for Environmental Chemical Sensing : Eduard Llobet, Universitat Rovira i Virgili (Spain) and Marcel Bouvet, Université de Bourgogne (France)
Authors : G.G. Mandayo, J. Gonzalez-Chávarri, I. Castro-Hurtado, E. Castaño
Affiliations : Ceit and Tecnun, Paseo Manuel Lardizabal 15, 20018 San Sebastián, Spain CIC microGUNE, Goiru kalea 9, Polo de Innovación Garaia 20500, Arrasate-Mondragón, Spain.

Resume : Metal oxide materials have been widely researched for many years as sensing material for conductometric gas sensors. Lately, the nanostructured forms of such materials have become a hot-topic of many investigations. On one hand, nanostructured materials show a higher surface-to-volume ratio, which can improve gas diffusion through the material, and on the other hand, the size of nanostructures, generates changes in the conduction mechanism. In both cases, changes in the gas detection process can be observed. But the synthesis routes of metal oxide nanostructures are not always repeatable or easy to implement. This work describes routes to obtain nanostructured metal oxides as a last step of the fabrication process of a sensor, once heater and electrodes have already been fabricated. To that end, an in-situ growth method based on the VLS (Vapour Liquid Solid) procedure has been developed and characterized for tin oxide (SnO2) and zinc oxide (ZnO). Improvements in the time of response and lower detection limits have been observed with these materials.

Authors : Murat Bektas, Dominik Hanft, Daniela Schönauer-Kamin, Thomas Stöcker, Gunter Hagen, Ralf Moos
Affiliations : Department of Functional Materials, University of Bayreuth, 95447 Bayreuth, Germany

Resume : The sensing properties of the resistive gas sensor material BaFe1-xTaxO3-δ (0.1≤x≤0.5) were investigated. BFT fine powders have been prepared by mixed-oxide route. X-ray diffraction pattern showed that perovskite BFT phase can be obtained when the powders are calcined at 1350 °C. BFT thick films have been successfully deposited by the novel Aerosol Deposition Method (ADM) on alumina substrates with a thickness around 5µm on Pt electrodes in four wire configuration. With ADM, thick and dense ceramic films can be deposited at room temperature with a carrier gas under rough vacuum. The electrical response of the films was investigated first under various oxygen concentrations and in a wide temperature range between 350-900 °C. Between 700 and 900 °C, the sample resistance of BaFe0.7Ta0.3O3-δ (BFT30) is highly oxygen dependent but shows an almost negligible temperature dependency. BFT30 responds fast and reproducibly to a changing oxygen partial pressure even at 350 °C. The cross sensitivity of coated samples has been investigated in environments with various gases (C3H8, NO, NO2, CO, CO2 and H2O) in flowing synthetic air between 350 and 800 °C. BFT30 exhibits excellent sensing properties to NO between 300 and 450 °C in the range from 2.5 to 1000 ppm with a high selectivity towards the other investigated gas species. This semiconductor ceramic material is a good candidate for a temperature independent oxygen sensor at high temperatures and as a NO sensor at low temperature.

Authors : Cindy Schmädicke, Sebastian Pregl, Jan Voigt, Lars D. Renner, Larysa Baraban, Gianaurelio Cuniberti
Affiliations : TU Dresden

Resume : We present a gas sensing system that allows measuring gases in-flow with continuous pressure monitoring and temperature control up to 350 °C. As a first application, we demonstrate the detection of ammonia using silicon nanowire based resistive elements. Ammonia (NH3) is a toxic gas that finds widespread use in various industrial sectors, such as in agricultural and industrial chemistry as well as in environmental and medical applications [1]. However, even at low concentrations (approximately 25 ppm) NH3 can cause severe irritations in the respiratory tract [2]. Therefore a reliable monitoring of the ammonia concentration in the surrounding environment by means of special sensor system is crucial for diverse branches of human activity. The requirements for such a sensor system are high sensitivity (ppm-ppb range), selectivity, compactness, low power consumption and reliability. We have built gas sensor elements based on a parallel array of bottom‐up synthesized silicon nanowires (SiNWs) having lengths of about 5‐20 μm and an average diameter of 22 nm [3]. The undoped SiNWs were printed onto the Si-wafer substrate and contacted with an interdigitated electrode, patterned via UV lithography. By contacting several hundred nanowires with the parallel array, a high surface area is provided and device‐to‐device reproducibility is increased compared to single devices. A constant potential was applied and the relative resistance change was recorded when switching from pure nitrogen to the nitrogen-analyte mixture. We were able to detect NH3 concentrations between 0.5 and 20 ppm at room temperature. Following this procedure a reversible increase in resistance was observed. References: [1] B. Timmer, W. Olthuis, A. van den Berg, Ammonia sensors and their applications-a review, Sensors and Actuators B, 107, 2, 666-677, 2005. [2] L.G. Close, F.I. Catlin, A.M. Cohn, Acute and chronic effects of ammonia burns on the respiratory tract, Arch. Otolaryngol., 106, 3, 151-158, 1980. [3] S. Pregl, W.M. Weber, D. Nozaki, J. Kunstmann, L. Baraban, J. Opitz, T. Mikolajick, G. Cuniberti, Parallel arrays of Schottky barrier nanowire field effect transistors: Nanoscopic effects for macroscopic current output, Nano Research, 6, 6, 381-388, 2013.

Authors : Inga Tijunelyte a, Stephanie Betelu b , Anne-Caroline Schnepf b, Ioannis Ignatiadis b, Nathalie Lidgi-Guigui a, Erwann Guenin a, Timothée Toury c, Joyce Ibrahim c, Emmanuel Rinnert d, Marc Lamy de la Chapelle a
Affiliations : a Université Paris13, Sorbonne Paris Cité, Laboratoire CSPBAT, CNRS, (UMR7244), 74 rue Marcel Cachin, 93017 Bobigny, France; b BRGM, Direction de l’Eau, Environnement et Ecotechnologies, D3E/SVP, 3 avenue Claude Guillemin - BP 36009, 45060 Orléans, France; c Université de technologie de Troyes, Laboratoire de Nanotechnologie et d’instrumentation Optique, Institut Charles Delaunay, FRE 2848, 12 rue Marie Curie, 10010 Troyes, France; d IFREMER, Service Interfaces et Capteurs, Département Recherches et Développements Technologiques, BP70, 29280 Plouzané, France

Resume : The European Water Framework Directive (Directive 2000/60/EC) aims at a good quality of water supplies in European Member States. In this context, developing analytical tools, allowing on-site accurate and sensitive water quality monitoring, is of primary importance. Surface Enhanced Raman Spectroscopy (SERS) has been proposed as a highly sensitive technique allowing fast sample screening with minimal handling. Interest using SERS includes both quantitative and qualitative sample analysis, which permits discrimination of individual analytes for their identification in complex systems. Herein, the design of SERS-based nanosensor is presented. As a substrate, gold nanocylinders, produced by Electron Beam Lithography (EBL) with controlled size and shape was used. For the surface coating aryl diazonium salt was selected for two main reasons. Firstly, the covalent bonds formed during diazonium salt grafting are known to be stronger than those created by self-assembly monolayers (SAMs). Secondly, grafted molecular layer enables to attract aromatic pollutants by non-covalent interactions which lead sensors to be washed and reused. Repeatability measurements conducted five times showed a Relative Standard Deviation inferior to 2%. In this report we present the spectral differences observed during all surface functionalization steps, including diazonium salt synthesis. We demonstrate the capability of diazonium salt based nanosensor to pre-concentrate organic pollutants, by sensing toluene and naphthalene in ppm concentrations. Moreover, the calibration curves and the study of the time dependant sensing of pollutant is presented. The authors want to acknowledge the ANR REMANTAS project (ANR-11-ECOT-0010) for financial support.

Authors : Mr Francesco Di Maggio, Dr Chris Blackman, Dr James Covington, Dr John Saffell, Mr Alan Tsang
Affiliations : Di Maggio, Blackman, Tsang University College London Christopher Ingold Building (Chemistry Dept) 20 Gordon Street WC1H 0AJ London; Covington School of Engineering, University of Warwick, Coventry, CV4 7AL; Saffell Alphasense 300 Avenue West Skyline 120 Great Notley Essex CM77 7AA

Resume : Against a host of competing gas sensing technologies, chemoresistive sensors are well positioned with great market opportunities due to their low cost, high sensitivity, fast response, relatively simple architecture and potential to be miniaturised. However drawbacks such as limited selectivity, stability and humidity dependence limit their general applicability. The ability to create materials with defined features such as the microstructure size/shape of the particles provide routes to address these issues and improved sensing properties have been achieved by decreasing the particle (grain) to the nanometer scale whereby surface states effectively extend through the entire particle. Similarly it has been shown that the addition of metal catalyst particles to the material matrix (i.e. functionalisation) address problems such as selectivity and stability. Aerosol Assisted Chemical Vapour Deposition (AACVD) is a relatively new method for growth of nanostructured materials allowing selective synthesis of nanostructures which can be integrated directly with sensor fabrication without the use of intermediate steps such as wet or dry transfer of pre-grown nanomaterials. Here we report the fabrication of gas sensors based on non-functionalised and gold-functionalised metal oxides synthesized in a single-step via a novel AACVD route and their sensing properties towards common air pollutants.

Authors : Shanqing Zhang
Affiliations : Centre for Clean Environment and Energy, Griffith School of Environment, Gold Coast Campus, Griffith University, QLD 4222, Australia

Resume : Abstract A series of nanostructured TiO2 sensors and photoelectrochemical cells have been developed in our group for photoelectrochemical determination of organic compounds, leading to a series of commercialized patents [1] and commercial products. This sensing mechanism is based on photoelectrocatalytic oxidation of organic compounds in waters under UV radiation [2-4]. Recently, a hydrogenated nanostructured TiO2 photoanode was prepared by hydrogenating TiO2 nanorod arrays (H-TNRs) electrode. Hydrogenation is an efficient and effective means to extend light absorption to visible light region and improve electron conductivity of TiO2 via introduction of oxygen vacancy and mid-gap levels in TiO2 lattice. The H-TNRs photoanode was used as a sensor for organic compound detections under visible light illumination for the first time. Preliminary experiments demonstrate that the H-TNR electrode is able to sensitively determine various organic compounds in water with satisfactory stability. This suggests that the hydrogenation nanostructured TiO2 electrodes are promising in sensing organic compounds in waters and further to be further developed into commercial products. References: 1. Zhao, H., Zhang, S., Improved water analysis. PCT Int. Patent. (2008) WO 2008077191 2. Qiu J., Zhang S. , Zhao H., Recent Applications of TiO2 Nanomaterials in Chemical Sensing in Aqueous Media, Sensors & Actuators: B. Chemical, 2011, (2011); 160: 875-890 (Review) 3. Zhang S., Li H., Zhao H., A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters, Environmental Science and Technology, 2009, 43, 7810–7815. 4. Zhang S., Jiang D., Zhao H., Development of chemical oxygen demand on-line monitoring system based on photoelectrochemical degradation principle, Environmental Science and Technology, 2006, 40, 2363-2368.

12:30 Lunch    
Poster Session 2: Technologies for Chemical Sensing Applications : Michele Penza, ENEA (Italy) and Albert Romano-Rodriguez, Universitat de Barcelona (Spain)
Authors : Shalini Jayakumar 1, Kamatchi Jothiramalingam Sankaran 1, Chi-Young Lee 1*, Nyan-Hwa Tai 1, and I-Nan Lin 2*
Affiliations : 1Department of Material Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan, R.O.C. 2Department of Physics, Tamkang University, New-Taipei, Taiwan, R.O.C.

Resume : Heavy metal pollution, caused by the waste streams of metal plating facilities, mining operations, and tanneries are not biodegradable and tend to accumulate in living organisms, causing various diseases and disorders to the nervous, immune, reproductive and gastrointestinal systems.1 Electrochemical method is one of the most favorable techniques for the simultaneous determination of environmental pollutants because of its low cost, high sensitivity and easy operation. Here, we explore diamond nanowire (DNW) electrode for the electrochemical deposition of samarium hexacyanoferrate2 (SmHCF) as electroactive materials for chemical sensors. The DNW electrode has been synthesized on silicon substrate by N2-based microwave plasma enhanced chemical vapor deposition. The SmHCF deposited on the surface of the DNW electrode by potential cycling from +0.8 to -0.2 V. The SmHCF found to grow on the surface of the DNW electrode with each potential cycle, as revealed by the change of peak currents with each cycle. A well-separated voltammetric peaks for the simultaneous detection of Cd2+, Pb2+, Hg2+, Cu2+, and Zn2+ toxic metal ions are obtained using SmHCF/DNW electrodes in differential pulse voltammetry measurements. Consequently, the DNW electrode with large surface area3, good chemical stability, and SmHCF makes the electrode an efficient chemical biosensor.

Authors : A. Hajjaji1,2, A. Labidi3, , B. Bessais2, M. Gaidi and M. A. EL Khakani1*
Affiliations : 1 Institut National de la Recherche Scientifique, INRS-Énergie, Matériaux et Télécommunications, 1650, Blvd. Lionel-Boulet, Varennes, Québec, Canada J3X 1S2 2Laboratoire de Photovoltaïque, Centre de Recherches et de technologies de l’énergie, Technopôle de Borj-Cedria, Tunisia 3 Unité de Recherche de Physique des Semi-conducteurs et Capteurs, IPEST, BP 51, La Marsa 2070, Tunis, Tunisia

Resume : A set of Cr-highly doped TiO2 samples with Cr contents ranging from 2 to 17 at.% were deposited on to oxidized silicon and glass substrates by the RF magnetron sputtering method and calcined at a temperature 550C. The microstructure and surface morphology of the sputter-deposited films were studied by means of X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. The Cr inclusions were found to coexist under both metallic and oxidized forms in the films. By subjecting the TiO2:Cr films to post-annealing treatment (at 550 °C), their crystalline structure was found to be sensitive to their Cr content. The optical constants (n and k) and band-gap of the Cr-doped films were obtained, as a function of the Cr content, by using variable angle spectroscopic ellipsometry and UV-Vis optical spectrophotometry. It is shown that the optoelectronic properties of the films can be tuned by controlling the metal concentration. The band-gap value is found to decrease from 3.3 eV to 2 eV as the sputtering power applied to the Cr target is increased from 0 to 150 W. This band-gap decrease is also accompanied by an increase of the refractive index of the films. On the other hand, the UV–VIS spectroscopy results indicated that as the Cr doping is increased, the transmittance edge of the titanium oxide film shifts from the UV region toward the visible range. The effect of Cr doping on the ethanol sensitivity, response and recovery time of TiO2 thin films was studied using in-situ electrical conductivity measurement.

Authors : M.Voinova
Affiliations : Chalmers University of Technology, Göteborg, Sweden

Resume : Acoustic piezoelectric resonators are widely used as precise analytical chemistry tools for the real time monitoring of a negligibly small amount of surface-attached mass of biological components, in particular, in environmental biosensors measurements. The quartz crystal microbalance (QCM) and the surface acoustic wave (SAW)-based sensors considered in our work belong to the leading group due to their considerable advantages. These piezoelectric resonators are considered now as high resolution analytical tools allowing researchers to discriminate between components due to the selective polymer coating on the resonator surface. The gravimetrical measurements performed with the QCM or SAW-based sensors provide the experimental data with high precision for the detection of surface mass for the thin adsorbed layer rigidly attached to the oscillator surface. The new challenge is the analysis of soft and biological materials, where the viscous losses of energy can essentially influence measured characteristics. Recent advances in QCM-D technique include the possibility of simultaneous measurements of change in the resonance frequency and the dissipation. In the present work we develop a general theory of QCM probing soft and biological materials in biosensor applications. Modeling is the important part of the analysis allowing researchers to quantify the results of the experiments.

Authors : S. Kishimoto1)2), H. Song,2) J. Nomoto2), H. Makino2), T. Yamamoto2)
Affiliations : 1) Department of Mechanical Engineering, Kochi National College of Technology, 2) Materials Design Center, Research Institute, Kochi University of Technology

Resume : Carbon monoxide gas sensing properties of Ga doped ZnO (GZO) thin films were studied. The polycrystalline transparent GZO films with 50 nm thicknesses were prepared on alkali-free glass substrates at 200 °C by ion plating with DC arc discharge. Ga content doped was 3 wt%. During the growth process, oxygen gas was introduced into the deposition chamber to compensate for the oxygen deficiency. The oxygen flow rate was between 5 and 25 sccm. From the XRD measurement, the GZO films were found to show a very high level of orientation along the c-axis. From Hall-effect measurements, the resistivities of these films were in the range of 2.4-8.0 × 10(-4) ohm•cm with carrier concentration of 7.9-1.8 × 10(20) cm-3 and µ of 18.9-20.6 cm2/Vs. Before the evaluation of gas sensing properties, the GZO films with Au electrodes were applied a bias voltage of DC 3.0 V at temperatures below 330 °C in nitrogen gas flow of 400 sccm. The CO gas sensitivity of the GZO films was evaluated by measuring the current variation in the GZO films due to introducing CO gas. The concentration of the CO gas was in the range of 0.6-2.5 %. All GZO films showed a decrease of the sensing current due to introducing CO gas. It is considered that this unique reaction is related to the grain-boundary. The CO gas concentration of 0.6 % was detected at the low temperature of 230 °C.

Authors : Christian Bur, Manuel Bastuck, Andreas Schütze, Mike Andersson, Anita Lloyd Spetz
Affiliations : Linköping University / Division of Applied Sensor Science, Saarland University / Lab for Measurement Technology, Linköping University / Division of Applied Sensor Science, Linköping University / Division of Applied Sensor Science

Resume : Particle emission from traffic, power plants or increasingly, stoves and fireplaces poses a serious risk for our health. The harmfulness of the particles depends on their size and shape, but also on adsorbates. Particle detection for size and concentration are available on the market while determining the content is still a challenge. In this work, a measurement setup for characterization of dust and ash particles, resp. adsorbates is presented. For the proof of concept NH3 contaminated fly ash samples from a coal fired power plant equipped with a SCR system were used. The fly ash sample was placed on top of a heater substrate and heated up to several hundred degrees. A SiC-FET gas sensor was used to detect desorbing species by transporting the headspace of the heater chamber to the gas sensor with a small gas flow. In addition, the heater chamber can be by-passed with two valves and a gas line to achieve a stable baseline of the gas sensor, e.g. during placement of the particles. Accumulation of desorbing species in the heater chamber followed by transfer to the gas sensor is also possible. A mass spectrometer (MS) was placed downstream of the sensor as a reference. A clear correlation between the SiC-FET response with the NH3 signal of the MS was observed. In addition different levels of contamination can be distinguished. Thus, with the presented setup we are able to characterize particles, esp. adsorbates which contribute significantly to the harmfulness of the particles.

Authors : Geoff Henshaw, Ayo Afonja, Simon Naisbitt,
Affiliations : Aeroqual Ltd, Auckland, New Zealand

Resume : Selectivity is a sensor property that is often under-examined in studies of nanostructured metal oxide gas sensors but it assumes high importance in the context of ambient air quality measurement where the challenge is to measure small numbers of specific molecules in the “sea” of other chemical species present in the atmosphere. We have developed metal oxide gas sensor instruments that utilise a combination of scrubbers and smart sensor control to measure O3, NO2 and NOx at ppb resolution. Co-location data from urban air studies against reference analyzers will be presented which demonstrate they are immune to humidity and cross-interferences with drift rates as low as a few ppb per month. This work has led to a new sensor design in which the selective technology is miniaturised “on-chip” with further advantages of lower total power and cost.

Authors : A. C. Catto, L. F. da Silva, C. A. Escanhoela Jr, V. R. Mastelaro, S. Bernardini, K. Aguir,
Affiliations : Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil Instituto de Química, Universidade Estadual Paulista, Araraquara, SP, Brazil CNRS, IM2NP (UMR 7334), Aix-Marseille Université, 13397, Marseille, France

Resume : In the last years, the ozone gas sensors have been the subject of great attention for monitoring and determination of ozone gas concentration due to its high toxicity and effects to human health. Therefore the determination and continuous monitoring of ozone concentration has taken special interest in the last years due to its high toxicity and effects to human health. The zinc oxide (ZnO) compound is one of the most promising metal oxide for gas sensing applications due to the well-known high surface-to-volume and surface conductivity . Additionally, ZnO compound has been proved to be an excellent gas-sensing material for several gases, such as CO, NOx, ozone and ethanol. In this context, specials ZnO microstructures with different morphologies and high surface/volume ratio can overcome the limitations of the current commercial sensors. Motivated by these considerations, the goal of this study consisted to synthesize ZnO nanorods directly onto a SiO2/Si substrate with interdigitated Pt electrodes via hydrothermal method and evaluated its potential use as ozone gas sensor. In this study, we investigated the ozone sensing properties of as-prepared ZnO nanorods-like structures grown directly onto a substrate containing electrodes via hydrothermal method. The sensor response was studied for ozone concentration ranges from 0.08 ppm to 1 ppm at different operating temperatures. The ZnO nanorods displayed a short response time of 25 s and a recovery time of 88 s when exposed to 1 ppm of ozone at 250°C. Our results indicate that ZnO nanorods show a good sensitivity to the presence of ozone, even when exposed to a low concentration (0.08 ppm).

Authors : William Bamogo(a), Laurent Mugherli(b), Armelle Novelli-Rousseau(c), Frédéric Mallard(c) and Thu-Hoa Tran-Thi(a)
Affiliations : (a) CNRS, DSM, SPAM, URA CEA-CNRS 2453, 91191 Gif-sur-Yvette Cedex, France; (b) CEA, DSM, SPAM, URA CEA-CNRS 2453, 91191 Gif-sur-Yvette Cedex, France; (c) bioMérieux, 38054 Grenoble Cedex 9, France

Resume : Tuberculosis, TB, is an infectious disease caused by Mycobacterium tuberculosis inducing 2 millions of deaths per year, in particular in poor countries. Diagnosing active pulmonary tuberculosis based merely on signs and symptoms is difficult. The most reliable tests are invasive, time-consuming or/and costly and there is a need to find new methods of TB detection. New ideas have emerged since this past 10 years for noninvasive diagnosis, with the detection of specific TB markers in breath via GC-MS techniques. In vitro studies showed that 140 volatile compounds are released by TB cultures, but only few of them can be identified as TB markers. In the present project, our objective is to detect a very specific TB marker, Niacin or nicotinic acid, present in sputum and breath. We will show preliminary results obtained with a luminescent probe molecule able to form a luminescent complex with niacin in solution. These results include the study of interfering compounds also present in breath and the description of strategies developed for the niacin detection in the gas phase, using sol-gel silicate thin film entrapping the luminescent probe.

Authors : F.Shao1, F.Hernández-Ramírez1 2, J.D. Prades2, N. López3, C.Fàbrega1, T. Andreu1, J.R.Morante1 2
Affiliations : 1 Catalonia Institute for Energy Research (IREC), E-08930 Sant Adrià del Besòs, Spain; 2 Department of Electronics, University of Barcelona, E-08028 Barcelona, Spain; 3 Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007 Tarragona, Spain

Resume : CuO nanowires (NWs) were successfully obtained by the thermal oxidation of Cu foils. Their electrical properties were evaluated at individual level and they were integrated in conductometric gas sensing devices. This p-type metal oxide exhibited a higher sensitivity to ammonia (NH3) than the previously reported for n-type SnO2 NWs, while the accurate analysis of the response to oxidizing and reducing gases revealed that oxygen species at the surface play a key role in their sensing mechanisms

Modelling of Sensors and Sensor/Gas Interaction : Albert Romano-Rodriguez, UB, Barcelona, Spain
Authors : Feng Shao1, Martin W. G. Hoffmann1 2, Joan Daniel Prades2, Joan Ramon Morante1 2, Núria López3, Francisco Hernández-Ramírez1 2
Affiliations : 1 Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià de Besòs, Barcelona, Spain; 2 Department of Electronics, University of Barcelona, Marti i Franquès 1, 08028 Barcelona, Spain; 3 Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, 43007 Tarragona, Spain

Resume : In this work, the adsorption of NH3 on SnO2 was examined by density functional theory (DFT) calculations and confronted to experimental data obtained with individual nanowire devices. We demonstrated that the sensing process of ammonia on tin oxide nanowires not only involves physical mechanisms but also has a concomitant chemical nature that requires two molecules of NH3 for the reaction to take place. Our theoretical modeling also revealed why ammonia sensing is competitive to the adsorption of water molecules. As a result, interfering effects in monitoring traces of NH3 intrinsically occur in humid air.

Authors : F. Shao a b, M.W.G. Hoffmann a b f, J.D. Prades b, R. Zamani a c, J. Arbiol c d, J.R. Morante a b, E. Varechkinae, M. Rumyantseva e, A. Gaskov e, I. Giebelhaus f, T. Fischer f, S. Mathur f, F. Hernández-Ramírez a b
Affiliations : a Catalonia Institute for Energy Research (IREC), Barcelona, Spain; b Department of Electronics, University of Barcelona, Barcelona, Spain; c Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, Bellaterra, Spain; d Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; e Chemistry Department, Moscow State University, Moscow, Russia; f Institute of Inorganic Chemistry, University of Cologne,Cologne, Germany

Resume : In this work, p-CuO (particle)/n-SnO2 (nanowire) heterostructures were evaluated as selective H2S sensors, and the working principle behind their good performance was qualitatively modeled. It was concluded that the main sensing mechanism is dissimilar to standard redox reactions typical of regular metal oxide (MOX) devices, and it can be ascribable to the sulfurization of CuO and the consequent variation of the p-n junction structure at the CuO-SnO2 interfaces. Experimental data showed that these individual nanowire H2S sensors suit well for alarm applications with extremely high selectivity and sensitivity to this gas for concentrations between 1 ppm and 10 ppm.

Authors : Ho Sun Lim
Affiliations : Electronic Materials and Device Research Center, Korea Electronics Technology Institute

Resume : Self-assembly of block copolymers (BCPs) provides a fascinating approach for creating photonic materials due to their ability to organize into 1D, 2D and 3D periodic microstructures with a long range order. Their periodic dielectric structures allow to modulate the propagation of electromagnetic waves, producing strong structural colors. Here, we demonstrate one-dimensionally periodic block copolymer photonic sensors with full-color tunability as a result of pH changes. The photonic lamellar gels were realized via the self-assembly of a hydrophobic block-hydrophilic block copolymer, polystyrene-b-poly(acrylic acids) (PS-b-PAA). The selective swelling of the PAA domains leads to extremely large tunability of the photonic stop band from blue to red wavelengths as a function of pH changes of aqueous solution. The reversible color changes and swelling behaviors are strongly dependent on the protonation/deprotonation of the acrylic acid groups in the lamellar microdomains. These tunable structural color materials may be attractive for pH-responsive photonic sensors.

Authors : Won Suk Chang1, Jung Hyun Kim1, Daeho Kim1 3, Seung Kwon Seol1 2
Affiliations : 1Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute (KERI), Changwon 642-120, KOREA;2Electrical Functionality Material Engineering, University of Science and Technology (UST), Changwon 642-120, KOREA;3Energy and Power Conversion Engineering, University of Science and Technology (UST), Changwon 642-120, KOREA

Resume : Conducting polymers such as polypyrrole (PPy), polyaniline (Pani), Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and their derivatives are very interesting materials because they combine tunable electrical transport characteristics and excellent mechanical properties. In particular, conducting polymers have been used as the active parts of gas sensors since early 1980s [1]. In comparison with most of the commercially available sensors, based usually on metal oxides and operated at high temperatures, the conducting polymer sensors have many improved characteristics. They have high sensitivities and short response time; especially, these feathers are ensured at room temperature. In this study, we fabricated a sensitive wire transducer in a chemiresistive gas sensor by a three-dimensional (3D) growth of PEDOT:PSS wires with arched shape. The wires were grown by controlled pulling of a micropipette (?Fountain-pen?) filled with a PEDOT:PSS solution (?Ink?) [2,3]. When the fountain-pen touched the substrate, a meniscus of the ink was created outside its opening and the solvent was evaporated at the same time. As the fountain-pen was pulled away, the meniscus was stretched and its cross section decreases, resulting in formation of wires. The individual positioning of grown wires was easily available by the 3D accurate control of fountain-pen. The as-prepared suspended PEDOT:PSS sensor which consisted of 10 wire array was tested for their ability to sense water, ethanol and acetone vapor gases at the room temperature. The sensor showed high sensitive, rapid, stable and reversible responses for detection of various concentrations of vapor gases, resulting from high surface area to volume ratio of the suspended wire. KEYWORDS Conducting polymer nanowire, Gas sensor, 3D suspended wire, Fountain-Pen lithography, Direct writing REFERENCES [1] Nylabder, C.; Armgrath, M.; Lundstrom, I., Proceedings of the International Meeting on Chemical Sensors, Fukuoka, Japan, 203 (1983). [2] Ji Tae Kim, Seung Kwon Seol, Jaeyeon Pyo, Ji San Lee, Jung Ho Je and G. Margaritondo, Advanced Materials 23 1968 (2011). [3] Seung Kwon Seol, Daeho Kim, Sunshin Jung and Won Suk Chang, RSC advances 2 8926 (2012).

Authors : Dayoung Lee, Qingling Xu, Songyi Lee, Xin Zhang
Affiliations : Jean Bouffard; Juyoung Yoon

Resume : We developed a colorimetric and fluorescent turn-on carbon dioxide sensor based on polydiacetylene, PDA-1, functionalized with amines and imidazolium groups. Our sensor design relies on the reaction of CO2 with alkylamines attached to imidazolium PDA to induce the blue-to-red phase change. Tethered primary amines react with CO2 to form carbamoate anions in the presence of an external base. Generated carbamoate anions partially neutralize the polymer's positive charges, inducing changes to backbone conformation and phase transition. PDA-1 allows for the selective sensing of CO2 with high sensitivity, down to atmospheric concentrations. Naked-eye detection of CO2 is accomplished both in water solutions of PDA-1 and in the solid state with electrospun coatings of PDA-1 nanofibers. Moreover, the photophysical characteristics of PDA-1 allow for the fluorimetric naked-eye detection of CO2 using widely available battery-powered green laser pointers as light source. Because of their simplicity and low cost, CO2 sensor based on PDA-1 may be useful in various environments. Reference 1. Xu, Q.; Lee, S.; Cho, Y.; Kim, M. H.; Bouffard, J.; Yoon, J. J. Am. Chem. Soc. 2013, 135, 17751−17754. 2. Guo, Z.; Song, N. R.; Moon, J. H.; Kim, M.; Jun, E. J.; Choi, J.; Lee, J. Y.; Bielaski, C. W.; Sessler, J. L.; Yoon, J. J. Am. Chem. Soc. 2012, 134, 17846. 3. Chen, X.; Kang, S.; Kim, M. J.; Kim, J.; Kim, Y. S.; Kim, H.; Chi, B.; Kim, S.-J.; Lee, J. Y.; Yoon, J. Angew. Chem., Int. Ed. 2010, 49, 1422.

Authors : Mandeep Singh, Maria Magliulo, Mohammad Yusuf Mulla, Antonella Mallardi, Luisa Torsi and Gerardo Palazzo
Affiliations : Dipartmento di Chimica, Universita degli Studi di Bari “Aldo Moro”, Bari, Italy-70126

Resume : Over the years, metal oxide based thin film transistors (TFTs) has attracted a great deal of attention due to their high charge-carrier mobility and excellent chemical/mechanical stability. In particular, zinc oxide (ZnO) has potential in transparent TFT owing to its high optical transparency and high conductivity [1]. We are presenting a solution processable ZnO based TFT in bottom and top gate configurations. ZnO thin films were prepared with the sol-gel spin coating method. The ZnO structure has been assessed by XPS and UV/VIS spectroscopy. For the bottom gate configuration, the ZnO thin film were calcined at different temperatures and time. The devices calcinated at 450 °C temperature for 5hrs shows higher mobility and Ion/Ioff ratio as compared with the devices processed at lower temperatures. The gating of the transistor has been performed with water and Posphate Baffer solution. Till now only one report is available on the water gated ZnO based TFT [2] and no report is found on the PBS gated. We have fabricated a water and PBS gated ZnO based thin film transistor without doing any further treatment of the ZnO surface. The devices so produced shows excellent characteristics with mobility as high as 0.168 cm2/Vs and Ion/Ioff ratio in the order of 104. These devices have the potential to be used for biosensing applications.

Authors : N-.J. Choi1, H-.K. Lee, S.E. Moon, and W. S. Yang
Affiliations : IT materials & Components Laboratory, Electronics and Telecommunications Research Institute

Resume : A gas sensor array based on metal oxide for monitoring of indoor environmental gases is fabricated. Indoor gases are HCHO, CO and C6H6. Four nano-size powders (SnO2, ZnO, In2O3, and WO3) with about 50 nm particle size are prepared as materials for gas sensing. The nanomaterials were characterized through optical microscopy, XRD, and SEM analyses. The materials were screen-printed onto the Si substrate followed by heat treatment. A array has four inter-digit patterns in front side which can be detected resistance of sensing material and a heater in back side which can operate until 500C. Prepared samples are sintered at 600C for 2h in electric furnace. Gas sensing properties are measured using a computer-controlled characterization system in range of 25ppb-2ppm. We investigated sensitivity, repeativity, selectivity, and response time of sensors. These sensors showed good sensitivities to indoor gases in the range of 250-350C. Repeated measurement showed very good consistency of within 10% in a full measurement range. Also, the response and recovery times of sensors were very fast within 10s. A semiconductor type sensor array proved that the cross-sensitive property will produce distinguishable selectivity. This work was supported by the IT R&D program of MKE/KEIT 276[10035570, Development of self-powered smart sensor node platform for smart & green building], and by the Ministry of Trade, Industry and Energy[Technology development project associated with commercialization].

Authors : V.M.Aroutionian,H.A.Zakaryan
Affiliations : Master student of Yerevan State University, Republic of Armenia, Yerevan, 0025, 1 Alex Manoogian

Resume : Development and applications of chemical sensors are very important today.There are many publications in this field.Investigations of graphene and sensors made of it and graphene oxide are very interesting[1,2].Below we report results of investigations of sensitivity of graphene.A comparison of properties of graphene and polymer humidity sensors made by us.It is based particularly on experimental results obtained in.Graphene sensors has remarkable response at much lower water concentrations(started 0.01 kg water vapor in 1kg air)compare to~40% of relative humidity for nanoporous polymer membranes is more than 150 GOhm at 40% of the humidity and drops 7,5 times at 60% of the humidity.The situation is practically the same for sensors made of hygroscopic polymer.Here the resistivity ~100KOhm drops several times in the same range of the humidity.Contrary to polymer sensors, the resistivity of graphene sensors increases on 150% at the humidity starting 0.02 kg/kg.At that, sensitivity of two-layer graphene is 1,5 times more compared single layer graphene.Value of the resistivity changes from 0.03 to 0.3 microOhm, which is easier to response of the resistivity measure then GOhms. We think that is connected with the graphene band opening phenomenon.To summarize, the graphene humidity sensors allow making very accurate control adsorption of water molecules on the surface graphene devices and integral circuits in future. 1.V.M.Aroutiounian,Arm.J.Phys.2013,v.6 2.F.Yaiari,Small,2011

Authors : *Nedilko S.G(1), Revo S.L.(1), Scherbatskii V.P.(1), Nedielko M.S.(2)
Affiliations : (1) Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine; (2) 2 E.O. Paton Electric Welding Institute of NASU, Kyiv, Ukraine

Resume : Cellulose is promising matrix suitable for sorption and stabilization of wide row of various type materials. The reason is porous, micro and nano-structured morphology of this material. Determination of traces of some of them is very important. There are drugs, heavy metals, and polycyclic hydrocarbons between them. We have investigated mentioned materials with aim to evaluate low concentration limits of their determination. Effectiveness of such materials sorption, hydrophobic are among them, is small. So, aimed to improve characteristics of some luminescent materials the directed modification of cellulose structure was made. There were ultra sonic affect and full or partial carbonization of cellulose. Studies of luminescence spectra, luminescence kinetics and luminescence excitation spectra of starting cellulose samples and doped with some luminescent oxide analytes (like to nitrates and chromate) and petroleum oils as well were curried on in wide region of excitation and registration wavelengths (200 - 1200 nm) and samples temperature. The given results were compared with known literature data and with results of our own investigation of the same luminescent analytes incorporated to some other solid matrixes

Authors : 1) T. Mazingue, M. Lomello-Tafin, M. Passard, L. Goujon, C. Hernandez-Rodriguez, 2) J.-L. Rousset, F. Morfin, 3) G. Maulion, R. D. Kribich, 4) P. Coudray, 5) T. Wood, J. Le Rouzo, F. Flory 6) J.-F. Laithier
Affiliations : 1) Université de Savoie, Laboratoire SYMME, BP 80439, 74944 Annecy le Vieux Cedex, France ; 2) Institut de Recherches sur la Catalyse et l’Environnement de Lyon IRCELYON, CNRS-University of Lyon 2 avenue Albert Einstein, F-69626 Villeurbanne Cedex, France ; 3) Université Montpellier II, Institut d’Électronique du Sud – IES, UMR CNRS/UM2 5214, Place Eugène Bataillon, 34095 Montpellier, France ; 4) Kloé SA, Hôtel d’Entreprise du Millénaire, 1068 Rue de la Vieille Poste, 34000 Montpellier, France ; 5) Aix-Marseille Université, Institut Matériaux Microélectronique Nanosciences de Provence – IM2NP, CNRS-UMR 7334, Domaine Universitaire de Saint-Jérôme, Service 231, 13397 Marseille, France ; 6) Comelec SA, Rue de la Paix 129 - CH-2301 La Chaux-de-Fonds, Switzerland

Resume : Increasingly restrictive limitations of pollutants require the development of more accurate detection devices. Although there are already a large number of sensors from mature technologies currently on sale, the detection of some gases remains problematic (limit of detection, time response, repeatability, cross-sensitivity, ...). We present here the main results of the PEPS (PEllet Photonic Sensor) project, aiming at developing a new transducer via a technological breakthrough : the combination of photonics (insensitive to external electromagnetic disturbances and deportation of the measurement fiber optic components) and catalysis (reversibility, limited energy consumption). Indeed, catalytic reaction are often exothermic and this heat of reaction can modify the properties of optical devices. The experimental studies performed during the PEPS project highlighted the rapid and reversible response at room temperature of catalytic powders towards different concentrations of CO and H2. The thermal and optical properties of the materials used for the photonic component have also been studied. These results have been exploited for the design of the photonic transducers. The feasibility of the physical transduction principle has been demonstrated by developing different prototypes based on Bragg gratings and Multimode Interference Couplers.

Authors : Marco Schüler, Tilman Sauerwald, Andreas Schütze
Affiliations : Saarland University, Laboratory for Measurement Technology

Resume : For the self-test of semiconductor gas sensors we combine two multisignal processes: TCO (temperature cycled operation) and EIS (electrical impedance spectroscopy). This combination enables the discrimination between irreversible changes of the sensor, i.e. poisoning, and changes in the gas atmosphere. When combining EIS and TCO, impedance spectra should be acquired in a short time period, in which the sensor can be considered time-invariant (i.e. milliseconds or less). For this purpose we developed a Fourier-based high speed, low cost impedance spectroscope. It provides a binary excitation signal through an FPGA (field programmable gate array), which also acquires the data. To determine impedance spectra, it uses the ETFE (empirical transfer function estimate) method, which calculates impedance by evaluating the Fourier transformations of current and voltage. Thereby, an impedance spectrum from ca. 60 kHz to 125 MHz is acquired in approx. 16 µs. We carried out TCO – EIS measurements with a GGS 1330 gas sensor (UST GmbH, Germany) using this spectroscope with a temperature cycle consisting of six equidistant temperature steps between 200 °C and 450 °C. Discrimination of different gases is possible by LDA (linear discriminant analysis) using only one type of data, thus enabling a validation of results by comparison of both methods. Finally, field tests of the novel system were performed in an underground parking garage.

Authors : Camelia FLORICA (a), Elena MATEI (a), Andreea COSTAS(a), Monica ENCULESCU(a), Maria Eugenia Toimil Molares (b), Ionut ENCULESCU (a)
Affiliations : (a) National Institute of Materials Physics, PO Box MG-7, 77125, Magurele-Bucharest, Romania; (b) GSI, Helmholtz Centre, Planck str. 1, D-64291, Darmstadt, Germany

Resume : Semiconductor ZnO nanowires(NWs) were prepared using the electrodeposition method in a polycarbonate template. By ultrasonication in alcohol the grown NWs were harvested and drop-casted on a SiO2/Si substrate. The optical, morphological and structural properties of the NWs were investigated. Photolithography and e-beam lithography were used for contacting single NWs. When Ti/Au metallic contacts were deposited on the NWs, ohmic electrical characteristics were obtained. Thus an appropriate framework was created for processing back gate field effect transistors, having as gate the N++ heavily doped Si substrate. The electrical measurements on the ZnO NW transistors have shown a clear increase of the source drain current with the voltage applied on the gate electrode. The parameters of the transistor were calculated and were highly improved when the surface of the NW was passivated with PMMA and AZ5214E. In this case the source drain I-V characteristics were saturating at higher applied voltages and the Ion/Ioff ratio was in the range of 10000 having a field effect mobility of about 100 cm2/(V•s). The characteristic parameters are among the highest reported in literature for such devices even when compared with NWs which were prepared by other methods, e.g. VLS or CVD. These highly sensitive, electrodeposited ZnO NW field effect transistors are excellent candidates for various sensor applications including here chemical or bio – molecules detection.

Authors : J.-M. Suisse, M. Bouvet, T. Sizun
Affiliations : Institut de Chimie Moléculaire de l’Université de Bourgogne (ICMUB), Université de Bourgogne, UMR CNRS 6302, 9 avenue A. Savary, F-21078 Dijon, France

Resume : Conductometric sensors such as resistors, often made of a molecular material processed into thin film over comb-shaped electrodes, have been used for many years as transducers. With those sensors, the change in conductivity of the molecular layer induced by interactions with the gas phase is taken as the primary source of information. Though small-sized and cost effective, conductometric sensors usually exhibit substantial current drift and suffer from much too slow kinetics to be used for real-time applications. Very few studies actually take interest in this fact, or even mention it, despite the growing needs in fast sensors especially for air-quality monitoring applications. This presentation will focus on key factors to enable the development of real-time-capable sensors and will show an example of application in the form of a new high performance toluene sensor based on an organic semiconductor. The conductometric sensor, which has been studied on a workbench specifically designed for real-time investigations, is made of an intrinsic p-type semiconductor (a radical lutetium bis-phthalocyanine), which exhibits ultra-fast-response times, full recovery, low current drift and high sensitivity towards toluene in the 20 - 450 ppm range. Thanks to these near-ideal characteristics, and as a proof-of-concept, the sensor has been successfully used on a new workbench to continuously monitor the concentration of toluene in gas phase, on a second-by-second basis.

Authors : T.-H. Nguyen(a,c), E. Chevallier(a), Cl. Beaubestre(c), C. Rivron(c), Y. Bigay(a), T.-H. Tran-Thi(c)
Affiliations : (a) ETHERA R&D, CEA-Saclay, Bât. 451, F-91191 Gif-sur-Yvette Cedex, France (b) Laboratoire d’Hygiène de la Ville de Paris, 11 rue Georges Eastman, 75013 Paris, France (c) CEA-Saclay, DSM/DRECAM/SPAM/Laboratoire Francis Perrin, URA CEA-CNRS 2453, 91191 Gif-sur-Yvette Cedex, France,

Resume : In swimming pools, chlorine (Cl2) is used as a disinfectant to minimize the risk to users from microbial contaminants. In water, Cl2 is transformed into HOCl which reacts with saliva, sweat, urine and skin, leading to the formation of several chloramines, such as monochloramine (NH2Cl), dichloramine (NHCl2) and nitrogen trichloride (NCl3). Because of its low solubility in water, NCl3 is essentially found in the air while NH2Cl preferentially remains in water. These compounds are toxic and their detection has become of great importance. However, there is currently no fast and selective method of measurement of NCl3 in the atmosphere nor of NH2Cl in water. The development of innovative chemical and colorimetric sensors for the direct detection of NCl3 and NH2Cl, is described. They are based on solid nanoporous materials synthesized via the sol-gel process. These materials display high adsorptive properties and the pores are tailored to become efficient nanoreactors. These nanoreactors, are designed to enhance a specific reaction between a probe molecule and NCl3 or NH2Cl, leading to coloured products. With matrices doped with NaI and Amylose, an NCl3 sensor is produced which can detect NCl3 at ppb level within 20 minutes in humid atmospheres (RH : 60-80 %) at ambient pool temperatures. The NCl3 concentration range covered is 5 to 250 ppb. For the detection of NH2Cl, the Berthelot reaction is exploited with the formation of a final blue-green product absorbing in the visible with a maximum centered at 640 nm. The NH2Cl sensor can measure NH2Cl in water with a detection limit of 0.1 µM (1.8 ppb). We will show the comparison of the sensors performance to the currently used, but indirect, methods during campaigns of measurements in swimming pools.

Authors : Azhar Ali Haidry, Nora Kind and Bilge Saruhan
Affiliations : German Aerospace Center, Institute of Materilas Research

Resume : There has been increasingly high environmental pollution due to the air and surface transport systems, requiring the development of fast, reliable, cost-effective and stable monitoring systems for these emission gases. Especially NO2 has been primal portfolio of current research in a wide temperature range. For effective monitoring, a low cross-sensitivity is essential as well as high selectivity to NO2. It has been well documented that measurement conditions, such as background oxygen and humidity, can significantly affect the sensor properties. In this work, aluminum doped and undoped SnO2 based sensors were characterized for NO2 monitoring under humidity. Both sensing materials were deposited on Al2O3 substrates (having already inter-digital Pt electrodes) via reactive magnetron rf-sputtering technique. The crystal structure and surface morphology of the sensing layers was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The sensing behavior of the layers towards NO2 was investigated at operating temperatures in the range of 300 – 600 °C. The time dependent sensor responses to various NO2 concentrations (50 – 200 ppm) were recorded in pure and humid argon environments, yielding improved and faster sensing behavior towards NO2 in humid Argon. Possible sensing mechanisms are evaluated for their suitability to these sensors.

Authors : Mario Eduardo de Barros Gomes e Nunes da Silva, Leandro Tiago Manera
Affiliations : FEEC / UNICAMP

Resume : Te main goal of this work is to design and manufacture a bolometric sensors array triggered by NMOS transistors operating in key mode. In this paper was performed the simulation of manufacture and operation of a set consisting of a bolometric resistor and transistor. The resistor is connected in series with the transistor drain. When the transistor gate is biased the transistor allows flow current through the resistor. The transistor has channel length of 1 µm, and transconductance of 280 mS. The resistor, made in doped polysilicon, has a resistance of 60 kohm. The set switching time is approximately 100 ms. We expect to get a voltage gain when the transistor is biased with the voltage source. We also expect that the switching system avoid errors in bolometers reading, because it allows each bolometer of the array is triggered independently in a active pixel system. The Silvaco software was used for the simulations of manufacture and operation.

Authors : T. Yamamoto1), H. Song1), J. Nomoto1), H. Makino1) and S. Kishimoto1,2)
Affiliations : 1)Kochi University of Technology; 2)Kochi National College of Technology

Resume : We have investigated hydrogen sensing of heavily Ga-doped ZnO (GZO) polycrystalline films. We deposited 50-nm-thick GZO films on glass substrates (@200 ºC) by ion-plating with dc arc discharge. A sintered ZnO tablet with a Ga2O3 content of 3 wt.% was used as a deposition source. Hall effect measurement results showed electrical resistivity of 2.36×10-3 Ωcm, carrier concentration of 1.89 ×1020 cm-3 and Hall mobility of 14.0 cm2/Vs. Analysis of data obtained by XRD measurements shows that the films consist of wurtzite structure with a preferred c-axis orientation perpendicular to the substrates. The gas sensing properties toward hydrogen gas (the concentration in air of 1 volume%) strongly depended on operating temperature. We found as follows: (1) a change in electric current of +0.1 to +0.2 mA at 150 ºC; (2) a change in electric current of -5.0 mA at 330 ºC. The findings imply that the gas sensing mechanism at the high operating temperature is significantly different from that at the low operating temperature. We will propose that the mechanism at the low temperature is limited by chemical reaction between hydrogen gas and oxygen atoms with a negative charge in the grain bulk, generating free carriers to increase carrier concentration, whereas a factor limiting the mechanism at the high temperature is concentration of hydrogen molecules physically adsorbed at the grain boundary, enhancing a barrier height to carriers at the grain boundaries to decrease carrier mobility.

Authors : Shinji Nakagomi, Keigo Yokoyama, Yoshihiro Kokubun
Affiliations : Faculty of Science and Engineering, Ishinomaki Senshu University

Resume : Field-effect hydrogen gas sensor devices with a structure of series connection between Schottky junction and beta-Ga2O3/6H-SiC heterojunction were fabricated. Beta-Ga2O3 and 6H-SiC are semiconductor materials with wide band gap of 4.9 eV and 3.02 eV, respectively. Beta-Ga2O3 thin films were deposited on p-type and n-type 6H-SiC substrates by gallium evaporation in oxygen plasma. An ohmic electrode was formed on SiC substrates. Pt was evaporated on the beta-Ga2O3 layer as a Schottky electrode. The both devices based on the p-type and n-type SiC had rectifying properties. The current of the Pt/Ga2O3/p-SiC device increases when the p-SiC is biased in positive. While, the current of the Pt/Ga2O3/n-SiC device increases when the n-SiC is biased in negative. Hydrogen sensing properties of both types device were measured at 300~500oC. The forward current of the Pt/Ga2O3/p-SiC device was increased largely for exposure to hydrogen. In contrast, the reverse current little changed for hydrogen gas. In the forward bias condition, hydrogen gas causes to lowering in resistance of the Schottky junction biased in reverse and gives rise to an increase in forward bias of Ga2O3/p-SiC junction. This amplification effect leads to a large change of forward current. Hydrogen sensing properties were obtained in the Pt/Ga2O3/n-SiC device in reverse direction. Also in forward bias condition, change of property was observed though the voltage shift under constant current was smaller but quicker.

Authors : Binas V.,1,3 Noshchenko O.,4 Kuscer D.,4 Gagaoudakis E.,1,2 Malic B.,4 Kiriakidis G.1,2
Affiliations : 1 Institute of Electronic Structure and Laser (IESL), FORTH, P.O. Box 1527, Vasilika Vouton, GR-70013 Heraklion, Crete, Greece 2 Physics Department, University of Crete, 710 03 Heraklion, Crete, Greece 3 Quantum Complexity & Nanotechnology Center (QCN), Department of Physics, University of Crete, GR – 71003, Heraklion, Greece 4 Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia

Resume : Printing electronics is a rapidly developing field associated with the need for flexible, economically viable products with advanced functions, this includes large-area flexible displays, LEDs, solar cells, and sensors. UV detectors have a wide range of applications in many areas, such as missile launching detection, UV radiation calibration and monitoring, environmental monitoring, space research etc. Environmentally friendly precursor solutions with ink-jet printing, allows cheap and simple processing of metal oxide films on rigid (i.e. glass) and flexible (i.e. PET) substrates. In the present study, a general protocol for processing cost-beneficial, environmentally benign aqueous-type suspensions containing metal-oxide nanoparticles, and their patterning with piezoelectric ink-jet printing technology based UV photo-detector is presented. We discuss and illustrate, on a doped titania (TiO2) powder, the processing of a highly stable, colloidal, water-based suspension containing particles smaller than 300 nm, prepared by a ball-milling process. For the ink-jet printing experiments, the surface tension and viscosity of the suspension were modified by the addition of a small amount of the appropriate non-ionic amphiphiles and glycerol. Based on this material a UV-sensor was fabricated on glass, and PET substrates with very fast response time (1msec) and high sensing characteristics (4 orders of magnitude change of current) as a promising candidate material for UV photodetector.

Authors : J.R. Sanchez-Valencia, M. Alcaire, P. Romero-Gómez, M. Macías-Montero, F.J. Aparicio, A. Borras, A.R. González-Elipe, A. Barranco
Affiliations : Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Materiales de Sevilla (CSIC-Universidad de Sevilla). c/Américo Vespucio 49, 41092 Sevilla, Spain.

Resume : ZnO is a fluorescence material characterized by one emission line in the near UV range of the spectrum associated with excitonic decay processes and a broad emission in the visible linked with electronic defects in the gap. It is recognized that the relative ratio between the excitonic and defect emissions depends on the crystallization and agglomeration states of ZnO. In this work we report the synthesis of ZnO nanocolumnar porous thin films by plasma enhanced chemical vapor deposition1 that, despite of their relatively porous character, only presenting an intense fluorescence emission at room temperature. It is found that the emission intensity is quite sensitive to the presence of oxygen in the medium and its evolution as a function of the oxygen concentration can be utilized for the photonic sensing of this gas in the environment. In addition, the system is also able to respond to the oxygen concentration dissolved in water and other liquid medium where the sensitivity of detection can be one or two order of magnitudes higher than that of commercial detectors based on electrochemical methods. The mechanism of detection and the development of a new generation of photonic sensors of oxygen based in pure ZnO are discussed. 1.- P. Romero-Gómez, J. Toudert, J.R. Sánchez-Valencia, A. Borrás, A. Barranco, A.R. González-Elipe. Journal of Physical Chemistry C 114, 20932–20940 (2010).

Authors : J. Gonzalez-Chavarri, I. Castro-Hurtado, G. G. Mandayo, E. Castaño
Affiliations : Ceit and Tecnun, Paseo Manuel Lardizabal 15, 20.018, Donostia, Spain CIC microGUNE, Goiru kalea 9, 20500 Arrasate-Mondragón, Spain.

Resume : One of the most competitive technologies in gas sensors are the conductometric sensors based on metal oxide semiconductors where the sensitivity is related to the surface of the sensing material. So, 1D nanostructures are promising candidates for that purpose. ZnO nanostructures have been proven to be highly sensitive to various gases and there are several techniques to fabricate them easily. For this reason, a sensor based on ZnO nanostructures is being developed to monitor the indoor air quality. The microsensor, whose size is 2.5x2.5mm, is fabricated on an alumina substrate. A Pt microheater and the interdigitated electrodes are deposited at the same DC sputtering process on the same side of the substrate. For the nanostructure growth, a zinc thin film layer is deposited over the electrodes and the samples are entered in a tube furnace for the annealing treatment. When the temperature starts increasing with the nitrogen flow, the zinc starts to melt and small particles are generated. When the oxygen flow enters the furnace, zinc particles are oxidized on the surface and a continuous diffusion of Zn particles produce the growth of the nanostructures. The main advantage of this method is that the nanostructures can be grown in-situ over the electrodes for the electrical characterization of the sensor. This sensor has been tested under benzene, formaldehyde and nitrogen dioxide and the lowest detection limits achieved for these gases are 500ppb, 100ppb and 50ppb respectively.

Authors : Joe Briscoe, Sabina M. Hatch, Steve Dunn
Affiliations : Joe Briscoe, Steve Dunn: Queen Mary University of London, UK; Sabina M. Hatch: University College London, UK

Resume : UV photodetectors are used in many applications including biological and chemical analysis, flame sensing and astronomical studies. UV can be damaging to humans and many materials, but also can be used in air, water and food purification; therefore UV monitoring can be used to assess potential harm or to control dosing. UV photodetectors typically require an external bias, but for self-sufficient sensors systems power sources such as batteries add considerably to their size and weight, and integration of sensors into multi-component nanosystems will be facilitated by self-powered functionality. We present a self-powered UV detector using a p-n heterostructure of CuSCN and ZnO nanorods produced using low temperature solution methods. At a nominal zero-applied field, the device produces a photocurrent response of 4.5 µA for a low UV (375nm) irradiance of 6.0 mW/cm2. A fast 500 ns rise and 6.7 µs decay time was recorded with a UV/visible rejection ratio of ~100. With a small applied bias of +0.1 mV a rapid detection time of 4 ns was possible. For comparison to similar heterostructures a responsivity of 9.5 A/W was measured at -5 V applied bias. The photodetector performance was attributed to the pre-existing Fermi-level alignment of the ZnO and CuSCN semiconductors, which resulted in a low turn-on voltage of ~0 V and photovoltaic behaviour. Therefore the ZnO/CuSCN UV photodetector is suitable for nanoscale applications that require rapid response times and self-sufficiency.

Authors : J. Sama 1, S. Barth 2, J.D. Prades 1, O. Casals 1, I. Gracia 3, C. Cané 3, A. Romano-Rodríguez 1
Affiliations : 1 MIND-IN2UB-Dept. Electronics, Universitat de Barcelona (UB), Martí i Franquès 1, 08028, Barcelona, Spain; 2 Institute of Materials Chemistry, TU Wien, Getreidemarkt 9/165, A-1060 Vienna, Austria; 3 Institut de Microelectrònica de Barcelona, IMB-CNM-CSIC, 08193 Bellaterra, Spain

Resume : Nanowires (NWs) have emerged as an important topic of research due to their high aspect ratio, and their capability to be part of new device architectures. Especially monocrystalline materials are important to achieve effective and known interactions of their surface in several applications, like gas sensors. An imporante issue that prevents the use of the nanostructures in functional electronic devices is their integration into a scalable process. Here we present a method for localized site selective direct growth of inorganic NWs that avoids several technological steps, reducing uncertainty factors of the process fabrication. VLS growth of SnO2 NWs is developed on top of CMOS compatible micromembranes with top interdigitated electrodes and buried integrated heater, which provides the thermal energy required for the growth. The SnO2 NWs show high crystalline quality and once the growth is finished, no post-processing is required because of NW bundles bridge the interdigitated contacts on top of the membrane. Thus, a scalable and time efficient process has been developed. The one-step fabrication device has been proven as a low power gas sensor, showing high response levels and low response times towards CO, NH3 and NO2 in a synthetic air atmosphere. The obtained devices will be shown as suitable for environmental gas sensing monitoring. The fabrication methodology will be described and its extension to the growth of other materials will be critically discussed.

Authors : Albert Romano-Rodriguez 1, Jordi Sama 1, J. Daniel Prades 1, O. Casals 1, Francisco Hernandez-Ramirez 1 2, Sven Barth 3
Affiliations : 1 MIND-IN2UB-Dept. Electronics, Universitat de Barcelona (UB), Martí i Franquès 1, 08028, Barcelona, Spain; 2 Institut de Recerca en Energia de Catalunya (IREC), E-08930 Sant Adrià de Besós, Spain; 3 Institute of Materials Chemistry, TU Wien, Getreidemarkt 9/165, A-1060 Vienna, Austria

Resume : Semiconducting nanowires (NW) are very attractive materials for gas sensing applications due to their high aspect ratio, that results in strong interactions between their surface and the surrounding atmosphere, giving rise to important electrical changes in the nanomaterial. Heating the NW is required to reach the right operation temperature. When operating with one single NW, the same current that is used to measure the resistance can be used to provide the NW heating, dramatically reducing the power consumption of the device. Here we present a single metal oxide nanowire gas sensor with ultra low power consumption based on this principle. Defect-free monocrystalline SnO2 nanowires were synthesized by chemical vapor deposition of a molecular precursor [Sn(OtBu)4]. NWs were dispersed onto a substrate with prepatterned electrodes and a Focused Ion Beam machine equipped with a Pt precursor was used to contact the individual NW to the electrodes. Very low level of currents, below of 1 µA, are enough to bring the nanomaterial to temperatures in excess of 150ºC, at which the reaction between surface adsorbed oxygen and reducing or oxidizing species takes place, while allowing the resistance variation to be measured. High response and low response times have been obtained against NO2, and a mixture of NO2 with humidity in a synthetic air atmosphere. The advantages and drawbacks of the approach to develop these advanced ultra-low power consumption gas sensors will be discussed.

Authors : O.Monereo, G. Vescio, S. Claramunt, O. Casals, J.D. Prades, A. Cirera, A. Cornet
Affiliations : MIND/IN2UB Electronics Department, Universitat de Barcelona, Spain

Resume : One of main advantages of carbon based sensors is their low temperature of operation, compared with materials such as metal oxides [1]. Among carbon materials, carbon nanofibers (CNFs) show very attractive properties for environmental gas sensing [2], at a moderate production costs. However, the knowledge about the sensing mechanisms in this material is very limited. In this work, we study of the interference of water and oxygen on the response of CNFs conductometric gas sensor, at different operation temperatures (<150ºC), and under ultraviolet light. From a fundamental perspective, our results show that, at different working conditions, different competitive mechanisms between both species on the CNFs surfaces occur. From a practical perspective, our experiments confirmed that at low temperatures (<80ºC) and low ultraviolet light intensities, CNFs are suitable for environmental relative humidity sensing. Moreover, the baseline and the responses of these sensors were highly stable and reproducible, even after several weeks of operation. The here-studied sensors were fabricated with a combination of inkjet printing and electrospray technique over flexible substrates [3]. [1] M. Penza, R. Rossi, M. Alvisi, D. Suriano, E. Serra, Pt-modified carbon nanotube networked layers for enhanced gas microsensors, Thin Solid Films. 520 (2011) 959–965. [2] O. Monereo, S. Claramunt, M.M. De Marigorta, M. Boix, R. Leghrib, J.D. Prades, et al., Flexible sensor based on carbon nanofibers with multifunctional sensing features., Talanta. 107 (2013) 239–47. [3] S. Claramunt, O. Monereo, M. Boix, R. Leghrib, J.D. Prades, a. Cornet, et al., Flexible gas sensor array with an embedded heater based on metal decorated carbon nanofibres, Sensors Actuators B Chem. 187 (2013) 401–406.

Authors : O.Monereo, S. Claramunt, G. Vescio, O. Casals, J.D. Prades, A. Cirera, A. Cornet
Affiliations : MIND/IN2UB Electronics Department, Universitat de Barcelona, Spain

Resume : To achieve good sensing performance, in terms of response time, reversibility and baseline stability, normally imply, conductometric solid-state gas sensors require and external an external source of energy, capable of stimulating the solid-gas interactions[1]. Ultraviolet light (UV) [3] is a viable alternative to the traditional strategy of heating the sensor material [2]. Here, we present a study on the use of UV to modulate the response of flexible gas sensors based on carbon nanofibers (CNFs). The sensing device was developed with a combination of different methods including the inkjet printing for the fabrication of the electrodes and electrospray technique for the deposit of the sensing material [4]. UV illumination was chosen first, to anneal the active layer in the fabrication process and then, to fasten desorption of the gas adsorbed, achieving a stable sensor signal. UV light was also proven to be an effective method to improve reversibility and response dynamics. In comparison with temperature modulation, UV illumination seems to be much more effective to improve the sensing characteristics. Characterization on the modulation of UV light was performed, focusing in the sensing of NH3 and NO2. Sensor response, response time and recovery time were fully characterized. A sensing mechanism is proposed in order to explain and verify the behavior of the CNFs sensor. NH3 and NO2 sensing is proven to be achievable with the correct UV light modulation. [1] Z. Zanolli, R. Leghrib, A. Felten, J.-J. Pireaux, E. Llobet, J.-C. Charlier, Gas sensing with Au-decorated carbon nanotubes., ACS Nano. 5 (2011) 4592–9. [2] J.D. Fowler, M.J. Allen, V.C. Tung, Y. Yang, R.B. Kaner, B.H. Weiller, Practical chemical sensors from chemically derived graphene., ACS Nano. 3 (2009) 301–6. [3] P. Qi, O. Vermesh, M. Grecu, A. Javey, Q. Wang, H. Dai, et al., Toward Large Arrays of Multiplex Functionalized Carbon Nanotube Sensors for Highly Sensitive and Selective Molecular Detection, Nano Lett. 3 (2003) 347–351. [4] S. Claramunt, O. Monereo, M. Boix, R. Leghrib, J.D. Prades, a. Cornet, et al., Flexible gas sensor array with an embedded heater based on metal decorated carbon nanofibres, Sensors Actuators B Chem. 187 (2013) 401–406.

Authors : M. Braik, C.Dridi, M. Ben Ali A. Ali, M. Abbes, M. Zabala, J. Bausells, N. Zine, N. Jaffrezic-Renault, A. Errachid
Affiliations : Université de Sousse, ISSAT de Sousse, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia / Université de Monastir, LIMA, Faculté des Sciences de Monastir, 5019 Monastir, Tunisia / Analytical Laboratory, Department of Applied Organic Chemistry, National Research Centre, Cairo, Egypt / Centro National of Microelectronica (IMB-CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain / Institut des Sciences Analytiques (ISA), Université Lyon, Université de Claude Bernard Lyon 1, UMR 5280, 5 rue de la Doua, 69100 Villeurbanne, France

Resume : Capacitive-voltage measurement (C(V)), as one of the most sensitive electrochemical methods, has been investigated extensively for the detection of environmental contaminants in recent years. In this work, we reported the development of a chemical sensor based on Co(II) phthalocyanine acrylate-polymer (CPAP) as a sensitive membrane for detection perchlorate anions. For this, we have used two type of transducer, silicon nitride (Si3N4) and Hafnium oxide (HfO2) grown by Atomic Layer Deposition (ALD) on silicon [1,2]. High dielectric constants of the produced HfO2 film facilitated the processing of the chemical sensor with considerably higher input capacitances than the standard Si3N4. The surface qualities of the used transducers have been studied by contact angle measurement. We have studied the pH effect on Si/HfO2/Electrolyte capacitance values for different phosphate buffer solutions (PBS). This optimization step have allowed a sensitivity value of about 46 mV/decade. We have developed also a perchlorate sensors based on Si3N4 and HfO2 transducers functionalized with CPAP membrane and characterized by C(V) measurements for different perchlorate concentrations (from 10-7 to 10-2 M). The sensor developed with HfO2 transducer shows better performances compared to that based on Si3N4 : a larger detection range (10-6 - 10-2 M and 10-4 - 10-2 M respectively) and a lower detection limit (10-6 M and 10-4 M). The specificities of our perchlorate sensor has been tested for some interfering ions (nitrate, sulfate and carbonate).

Authors : Inga Tijunelyte a , Nathalie Lidgi-Guigui a , Erwann Guenin a , Timothée Toury b , Marc Lamy de la Chapelle a
Affiliations : a Université Paris13, Sorbonne Paris Cité, Laboratoire CSPBAT, CNRS, (UMR7244), 74 rue Marcel Cachin, 93017 Bobigny, France; b Université de technologie de Troyes, Laboratoire de Nanotechnologie et d’instrumentation Optique, Institut Charles Delaunay, FRE 2848, 12 rue Marie Curie, 10010 Troyes, France

Resume : Surface enhanced Raman spectroscopy (SERS) is a highly sensitive technique, based on vibrational signal amplification due to the excitation of localized surface plasmons. 40 years of continuous studies and of technological improvements have led SERS to permit a quantitative and qualitative molecular detection at the trace concentrations. Moreover this technique has been applied in numerous different research fields, including environmental analysis. Nowadays, waters pollution by toxic substances raises a need of sensitive and reliable sensing tool, capable to operate in-situ. Herein, a study on the design of a SERS-based nanosensor, having the ability to pre-concentrate toxic substances in water will be presented. As a substrate for a nanosensor, gold nanocylinders, made by Electron Beam Lithography (EBL), were used to permit a Raman enhancement and to ensure analysis reproducibility. Concerning organic contaminants pre-concentration, chemically thiolated cyclodextrins were used to decorate the gold surface. The success of functionalization was observed by Localized Surface Plasmone Resonance (LSPR). Capability of cyclodextrins to form host-guest complexes with organic molecules such as toluene and naphthalene, was then monitored by SERS in liquid conditions. The detection limits reach for organic pollutants were in ppb concentration range. The authors want to acknowledge the ANR REMANTAS project (ANR-11-ECOT-0010) for financial support.

Authors : Filippo Fedi1, Filiberto Ricciardella2-3, Maria Lucia Miglietta2, Tiziana Polichetti2, Ettore Massera2 and Girolamo Di Francia2
Affiliations : 1 CNR-Institute for Composite and Biomedical Materials, Piazzale E. Fermi 1, Portici (Naples), I-80055, Italy; 2ENEA UTTP-MDB Laboratory, R.C. Portici, Piazzale E. Fermi 1, Portici (Naples), I-80055, Italy 3University of Naples ‘Federico II’, Department of Physics, Via Cinthia, I-80126, Naples, Italy

Resume : Solid-state gas sensors operating in environmental conditions generally suffer from slow and incomplete recovery to the initial value after the sensing signal. There is therefore a general request to develop a fast and efficient way aimed to restore the sensor. In the case of graphene-based chemiresistors used for NO2 detection, for example [1], it has been observed a poisoning effect on the material due to a simple environmental air exposure for >48h or to repeated exposure cycles. As a result, the sensing response shows smaller and smaller changes in conductance value. In this work we present a method to restore the exhaust chemiresistors that relies on the water capability to remove the adsorbed NO2[2]. Besides we report on the development of a simple and fast signal processing analysis to overcome the incomplete recovery. Colloidal suspension of graphene were prepared with liquid phase exfoliation (LPE) of graphite flakes in NMP [3,4]. Chemiresistor devices were prepared by drop-casting few microliters of graphene dispersions onto a transducer made with Au interdigitated electrodes printed on an Alumina substrate. After the preparation, a chemiresistor was mounted in a Gas Sensor Characterization System (GSCS) and exposed for 10 minutes to a flow of 350 ppb of NO2 in nitrogen (at T=25°C and relative humidity RH=50%) [1]. A conductance change as high as 27% was recorded highlighting a very high sensitivity to the analyte. The sensitivity completely dropped after the exposure to environmental air for more than one month. Exhaust chemiresistors were then dipped in water for one minute at high temperature (95°C) in order to increase the kinetics of the solubility process and dried at 150°C for few minutes in air. The device conductance was seen to enhance by more than 33% after the recovery treatment. The exceptionally high response obtained suggests that water was effective in removing the groups that pollute the transducers. On the other hand, the improvement of the sensing properties can be also hypothesized as due to the water treatment that was able to remove residues of the organic solvent employed in the graphene solution as well as to clean out the film surface. In summary, test results show that this recovery method is effective and could be profitable exploited to process exhaust sensing materials.

Authors : Inga Tijunelyte, Nathalie Lidgi-Guigui, Irena Milosevic Erwann Guenin, Marc Lamy de la Chapelle
Affiliations : Université Paris13, Sorbonne Paris Cité, Laboratoire CSPBAT, CNRS, (UMR7244), 74 rue Marcel Cachin, 93017 Bobigny, France

Resume : Among all cavitand molecules, cyclodextrins (CDs) are the most important due to their low price, commercial availability, non-toxicity and solubility in water. Cyclodextrins have been widely studied and applied in many research fields since their ability to form host-guest complexes with small hydrophobic molecules have been proven. The most common three forms of CDs are- alpha-CD, beta-CD and gamma-CD. The difference between them is the size of hydrophobic cavity formed by glucopyranose units (6, 7 and 8). Such cavitand are studied for the design of nanosensor dedicated to environmental pollution. In this context, the study of cyclodextrins host-guest complex formation with targeted substances is of great interest. Such interactions could be analyzed by Raman spectroscopy. Herein, the interaction of all three forms of cyclodextrin with three aromatic hydrocarbons: toluene, naphthalene and fluoranthene are presented. The proof of complex formation was achieved by vibrational spectroscopy and has been confirmed using thermogravimetric analysis. The obtained results demonstrate that affinity with regards to a size between targeted molecule and dimension of a cyclodextrin cavity, plays an important role in the inclusion complex formation an as well as in strength of the interaction between molecules. The authors want to acknowledge the ANR REMANTAS project (ANR-11-ECOT-0010) for financial support.

Authors : KACI Samira; KEFFOUS Aissa; MANSRI Omar; MENARI hamid
Affiliations : Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique , 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles, Alger, ALGERIE

Resume : we demonstrate that semiconducting films such as nanostructured lead sulfide (PbS) thin films, prepared by the chemical bath deposition (CBD)technique from aqueous solutions, can be used as sensing element in nitrogen dioxide (NO2) gas sensors. Various PbS-based Schottky-diodes nitrogen dioxide sensors, with the sensing layers grown in different baths deposition, have been fabricated. All the used growth mixtures allowed the obtaining of nanostructured thin films.The energy dispersive analysis (EDAX) confirms the chemical composition of the PbS. Current-voltage measurements of Pd/nc-PbS/pSi(100)(a-SiC:H)/Al Schottky structures were studied in presence of NO2 gas at room temperature. The gas sensing behavior showed that the synthesized PbS nanocrystalline thin films gave a rapid and stable response to NO2 gas The excellent NO2-sensing characteristicsare due to the fact that adsorption of the gas enhances the surface conductivity of the semiconducting layer. Moreover, the sensorgrown in presence of iodineat reaction temperature of 80°C perform better than others one. Lastly, it isverified thatnanostructured lead sulfide thin films can extend their field of applications from optical devices to environmental one.

Authors : Kirstin Bornhorst, Christian Schirrmann, Andreas Weder, Andreas Heinig, Florenta Costache
Affiliations : Fraunhofer Institute for Photonic Microsystems IPMS, Dresden, Germany

Resume : From the class of electroactive polymers, dielectric elastomers and electrostrictive polymers are known to exhibit very large mechanical strain and resilience. These polymers are becoming increasingly attractive for actuators, sensors as well as for robotics and energy harvesting applications. In this paper, dielectric elastomer and electrostrictive polymer thin films are compared in view of their potential for harvesting electrical energy from environmental vibrations. Various thin film stack configurations, including polymers of different elastic moduli, dielectric constants or electrostrictive constants, are employed to design energy harvesting microdevices. To investigate the polymer stack performance, i.e. energy gained upon mechanical compression, the stacks were subjected to dynamic deformation by means of a pneumatic piston of variable frequency and pressure characteristics. An autonomous, self-priming energy harvesting circuit was developed to induce an initial charged state and scavenge the additional energy stemming from the change of the polymer stack capacity on each compression cycle. With this system configuration, we obtained, for instance for a harvester based on a polymer of high electromechanical coupling, a harvested energy density per cycle of about 0.8 mJ/cm³ at 15 Hz. It is shown that, for the small footprint configurations investigated, electrostrictive polymers are the most promising to use as power generators for wireless sensor applications.

Authors : N. Bardi, I. Jurewicz, A. B. Dalton
Affiliations : Department of Physics, University of Surrey, Guildford, GU2 7XH, UK

Resume : We describe the spinning and characterization of high strength, conducting, carbon nanotube (CNT) fibres fabricated using our continuous coagulation technology. Our studies use both experimental and theoretical methods to determine the phase behaviour of liquid-dispersed CNTs as a function of nanotube length, aspect ratio, bending modulus, degree of nanotube bundling, temperature, dispersant type, nanotube type and dispersant concentrations. Variations in spinning parameters (such as injection rate, coagulation bath rotation speed, and coagulation flow rate) and coagulation bath properties (such as pH of the coagulation solution) are also studied as it dramatically affects fiber strength and morphology. Various properties of the resulting fibers as a function of process variables are characterised using techniques such as (a) static and dynamic mechanical strain; (b) optical spectra (UV to far IR regions); (c) Raman spectroscopy; (d) conducting Atomic Force Microscopy (AFM) and (e) X-ray diffraction are described. We show that these fibres directly respond to trace chemical exposures by undergoing large dimensional changes that provide actuation. These dimensional changes generate observed stresses which could be used to eliminate porosity in protective clothing. We also utilise the fact that the CNT based fibers are electrically conducting and can be used as radiation detectors or dosimeters. Photocurrent measurements as a function of time are performed on the CNT-polymer fibers as they are irradiated with an X-ray beam at different dose rates, where the dose rate is determined by the distance of the devices to the X-ray tube. This type of radiation sensitive fibres could be used for radiation detection. Moreover by incorporating these fibers into textiles, it should be possible to develop smart materials for active dosimetry clothing, capable of measuring whole-body radiation dose for workers in the nuclear industry.

Authors : M. Andersson, A. Lloyd spetz
Affiliations : Div of Applied Physics, Linköping University, SE-581 83 Linköping, Sweden

Resume : In order to reach the necessary sensitivity and selectivity of chemical gas sensors for applications such as air quality and environmental monitoring as well as control of low level pollutant emissions the interplay between transducer and materials design has to be taken into account during sensor development. Nothing will be gained by developing a material with a very strong and specific interaction with a target analyte if the transduction of that interaction into a readout signal is very weak. In this work we would therefore like to give some examples on selectivity and sensitivity improvements of the field effect sensor platform by the development of designs and materials. It has for instance been shown that by the choice of field effect sensor gate materials, e.g. the choice of Ir over Pt and Pd, the application of different biases can tune the selectivity towards one or another class of substances, exemplified by a higher selectivity towards a hydrogen containing substance such as ammonia compared to a non-hydrogen containing substance like CO at negative gate biases, and the opposite relationship at positive biases. Both the micro- and macro-structure of the gate material has thereby also been shown to be important. Furthermore, in going to thinner gate oxides, which can be possible for instance by the latest development of advanced high-k dielectrics, and designing oxides with higher density of and more polarizable adsorption sites, the sensitivity can be increased.

Authors : Thomas Roussel, Mohamed Marei, Robert Keynton, and Richard Baldwin
Affiliations : University of Louisville (Bioengineering), University of Louisville (Chemistry), University of Louisville (Bioengineering), University of Louisville (Chemistry)

Resume : Low-cost, microfabricated sensors and solar-powered instruments offer unique advantages for electrochemically-based, remote chemical sensing. To eliminate the need for calibration, our group has developed calibration-free detection of heavy metals in a palm-sized platform containing microfabricated Au electrodes in a thin-layer cell, where coulometric stripping of Cu and Hg as low as 6 ppb in a 1.8 µL volume (180 femtomoles) was demonstrated. Other metals such as Pb and Cd are reduced at more negative potentials where concurrent dissolved O2 (DO) reduction occurs and as such, DO is typically removed prior to analysis. To avoid in-field pretreatment, we are developing a miniaturized deoxygenation thin-layer manifold to actively and selectively reduce DO in the sample stream. This reduction is done at a Ag cathode separated from the sample flow stream by an O2 permeable membrane. Recent results of an early prototype showed 98% O2 removal at flow rates approaching 50 µL/min with low voltage and power requirements (1V and <200 mW•hr•L-1, respectively). This presentation will describe the second generation O2 removal platform which has been further miniaturized (approximately 2cm X 4cm X 6cm) and is powered by a solar cell and simple supporting electronics to allow continuous, remote, in-field deployment. Future work will incorporate fluid delivery, a miniaturized potentiostat, data storage, and a GSM modem for periodic communication over existing cellular infrastructure.

15:30 Coffee Break    
16:00 EMRS-2014 Plenary Session - No symposia parallel sessions    
18:30 Gathering of Day    
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Authors : Gábor Piszter (a); Krisztián Kertész (a); Zofia Vértesy (a); Zsolt Bálint (b); László Péter Biró (a)
Affiliations : (a) Institute for Technical Physics and Materials Science, Research Centre for Natural Sciences, H-1525 Budapest, PO Box 49, Hungary,; (b) Hungarian Natural History Museum, Baross utca 13, H-1088 Budapest, Hungary

Resume : Numerous insects possess structural colouration [1]. Butterfly wing scales containing 3D photonic nanoarchitectures exhibit measurable colour change when altering the ambient air atmosphere by different types of volatile vapours. This allows their use as optical vapour sensors [2]. The sensing mechanism is based on the capillary condensation of the vapours into the nanoarchitecture [3]. Our recent investigations showed that the colour differences of the species can be determined using an extended chromaticity diagram based on the four sensitivity functions of the receptors occurring in eyes of the Blue butterflies [4]. Therefore this chromaticity diagram can be used for the characterization of the spectral changes produced by the different vapours, too. We show that the spectral shift is vapour specific and proportional with the vapour concentration. The result of the chromaticity diagram analysis is compared to standard principal component analysis. The congruent result of the two methods shows that the gas sensing experiment could be performed using discrete wavelengths instead of broad-spectrum reflectance analysis which suggests the development of relatively small and low-cost vapour sensor system. [1] L. P. Biró & J. P. Vigneron, Laser & Photonics Reviews 5 (2011) 27–51. [2] L. P. Biró et al., Proceedings of SPIE 7057 (2008) 705706. [3] K. Kertész et al., App. Surf. Sci. 281 (2013) 49–53. [4] Z. Bálint et al., Journal of the Royal Society Interface 73 (2012) 1745–56.

Authors : Aristizabal, N., Ríos, X., Echeverría, J.C., Garrido, J.J.
Affiliations : Departamento de Química Aplicada. Universidad Pública de Navarra. Campus Arrosadía, 31006 Pamplona. Spain.

Resume : Research on sensing mechanisms and vapor-surface interaction is the key for developing FOs to detect VOCs in environment, healthcare, food quality, and industrial process control. So far, research on FOs has focused on the configuration and the films used as sensing elements. Less attention has been paid to the effect of temperature and the interaction of VOCs with the surface of films. We report experimental results on the effect of temperature in the range 5 – 50 ºC on the response of FOs that uses films of hybrid silica xerogels as the sensing elements. The xerogel films were prepared using the sol-gel process at pH 4.5 using mixtures of methyltriethoxysilane (MTEOS) or ethyltriethoxysilane (ETEOS), and tetraethylorthosilane (TEOS) in a 30:70 molar percentage, and affixed to the end of the optical fiber by the dip-coating technique. The measuring system works under volumetric static conditions. In the range 20 – 40 ºC, the response decreased with temperature, which can be attributed to the decrease in the adsorption of VOCs, which is an exothermic process. Below 20 ºC the response didn’t change with temperature that can be mainly attributed to the condensation of the analytes in the film. For temperatures higher than 45 ºC, adsorption is scarce. At a given temperature, experimental data agree with a model based on adsorption of VOCs molecules on the films that, in turn, changes the refractive index of the external medium. The interaction energy (Ea) was obtained by applying the Arrhenius equation to the experimental data in the range 20 – 40 ºC.

Authors : Mario Malerba, Ermanno Miele, Andrea Toma, Francesco De Angelis
Affiliations : Nanostructures Department, Istituto Italiano di Tecnologia

Resume : While planar nanostructured devices have reached outstanding spatial resolutions, the third dimension is still a challenge for nanofabrication. Metallized standing scaffolds are however of fundamental importance both in basic and technological research: applications may span from negative refractive-index metamaterials to optoelectronics, from wave-front engineering to sensors. In this context, we will first present a novel top-down approach to produce very high-aspect-ratio hollow plasmonic nanostructures, used as multi-purpose building blocks [1]. Next, we will report in detail on the field of optofluidics and liquid-environment biosensing: by exploiting the broadband optical absorption and the high electric field confinement and enhancement in the cavity of hollow extruded metal nanostructures, novel devices for few molecules detection are being conceived and tested, in the direction of early contaminant discovery and pollutant monitoring. REFERENCES: [1] F. De Angelis, M. Malerba, M. Patrini, E. Miele, G. Das, A. Toma, R. Proietti Zaccaria and E. Di Fabrizio, Nano Letters 13, 3553-3558 (2013).

Authors : Martin Eickhoff
Affiliations : I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen

Resume : Group III-nitride (III-N) nanowires (NWs) and nanowire heterostructures (NWHs) are a topic of current research. Besides the possibility of fabricating novel, nanoscaled optoelectronic devices with improved stability and efficiency the excellent optoelectronic properties and the high chemical and electrochemical stability of III-N nanostructures allows the realization of novel optochemical transducers as a base for integrated sensor systems with optical read-out. Generally, the dynamics of optically excited carriers in GaN nanostructures have been demonstrated to be affected by surface effects, modification of the internal field due to surface adsorption or non-radiative surface recombination. Such effects can be used for the realization of optically addressable chemical sensors, where chemically induced variations of the surfaces potential or interaction with surface states leads to a variation of the luminescence characteristics of GaN nanostructures. We show that the photoluminescence properties of GaN- and InGaN nanodiscs embedded in NWHs sensitively responds to the exposure to different gases and allows the realization of novel optochemical transducers. Complementary response mechanisms for the optical detection of reducing and oxidizing gases will be discussed. For application in liquid solutions we address the bias-dependent luminescence response of III-N NWs to variations of the pH value in electrolyte solutions and we discuss this behavior in terms of photoactivated hole transfer to RedOx-levels in the electrolyte solution. Concepts for integration of III-nitride NW transducers into optochemical sensor systems and the characterization of such sensor systems are also presented.

10:00 Coffee Break    
Catalytic Chemical Sensing Materials : Bilge Saruhan-Brings, German Aerospace Center (Germany) and Martin Eickhoff, Justus Liebig University of Giessen (Germany)
Authors : Ehsan Danesh , Krishna C. Persaud
Affiliations : School of Chemical Engineering and Analytical Science, The University of Manchester, UK

Resume : Ammonia is a chemical that is encountered in many different environments over a wide range of concentrations. Sensors are required that can cover a large dynamic range of concentrations. For instance, ammonia levels in the natural atmosphere can be very low, down to sub-ppb concentration. Hence, very accurate ammonia detectors with a detection limit of 1 ppb or lower are required for measuring such concentrations. On the other hand, near intensive farming areas, ammonia concentrations are much higher, above 10 ppm. The sensors need to work under high background humidity and under a range of temperature. Polyaniline has good (thermal/environmental) stability and provides reasonable conductivities required for most application fields. The material can be reversibly doped and undoped by electrochemical or chemical oxidation or reduction. While this material has previously been used for chemical sensing of ammonia, problems of reversibility, and difficulties in making reproducible sensors have limited its use. Here we report the development of a vapour phase polymerisation technique that allows the deposition of nanolayers of polyaniline onto interdigited substrates where a heater is incorporated. The resulting structure forms a heated chemiresistor that has improved reproducibility in manufacture as well as good reversibility on binding ammonia. By adjusting the dimensions and thickness of the polymer layer, a large dynamic range of ammonia concentrations can be measured. We have eliminated the need for solubilising polyaniline, and the process is fully compatible with large scale fabrication methods including printing technologies.

Authors : Christian Bur, Manuel Bastuck, Andreas Schütze, Mike Andersson, Anita Lloyd Spetz
Affiliations : Saarland University / Lab for Measurement Technology, Linköping University / Division of Applied Sensor Science, Linköping University / Division of Applied Sensor Science, Saarland University / Lab for Measurement Technology

Resume : Gas sensitive FETs currently based on silicon carbide (SiC-FET) as substrate material have been studied and improved for many years. Sensitivity and to some extend also selectivity can be adjusted by the catalytic gate material and its structure. Typical applications are usually exhaust monitoring from automotive or power plants. Lately it was also reported that volatile organic compounds (VOC) in the low ppb range can be detected by these sensors. However, developing a selective sensor/sensor system for distinguishing different compounds is still a challenge. Dynamic operation, e.g. temperature cycled operation (TCO), is a powerful tool to increase both the selectivity and the stability of chemical gas sensors. For FETs not only the operating temperature can be modulated but also the gate bias. Both TCO and gate bias cycled operation (GBCO) can enhance the sensor performance; in addition, GBCO can also be applied to gain a better understanding of the processes on the gas-sensitive gate and also within the FET structure. Due to the huge dimension of the obtained data sets feature extraction together with multi-variate statistics is used for evaluation, e.g. Linear Discriminant Analysis (LDA) or Support Vector Machines (SVM). With the outlined approach different VOCs, e.g. benzene, naphthalene and formaldehyde, can be discriminated. Detection of VOCs even in a high background of 2 ppm ethanol is possible. Hence, the performance of SiC-FETs is enhanced significantly.

Authors : Davide Carboni, Luca Malfatti, Alessandra Pinna, Barbara Lasio, Yasuaki Tokudome, Masahide Takahashi, Plinio Innocenzi
Affiliations : a) Laboratorio di Scienza dei Materiali e Nanotecnologie, D.A.D.U., Universita` di Sassari, CR-INSTM, Palazzo Pou Salit, Piazza Duomo 6, 07041 Alghero, SS, Italy; b) Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan

Resume : Nowadays the increasing level of ground water contamination, due to highly toxic organic pollutants (HTOPs), such as the organophospate pesticides, is becoming a serious threat especially for the neurotoxic effects associated with some of them. This issue has therefore arisen the need for new catalytic materials with water remediation capabilities. The present work is aimed at developing a titania-based mesoporous film with catalytic properties toward organophosphate pesticides by combining two different approaches: the molecular imprinting and the self-assembly with a supramolecular template. The mesoporosity of the material has been obtained by using a tri-block copolymer (Pluronic F127) as a micellar template while the molecular imprinted cavities have been templated by a complex between La3 and bis-4-nitro-phenyl-phosphate. The template removal allowed opening, in one step, both the mesopores and the imprinted cavities with a simultaneous estimation of the active sites. The catalytic activity of the molecularly imprinted and not imprinted films toward the pesticide Paraoxon? has been evaluated by means of UV-Vis spectroscopy titration of the 4-nitro-phenolate released by the Paraoxon? hydrolysis. The analysis of the initial rates of molecularly imprinted and not imprinted films has shown that the presence of a very low number of molecular cavities improves the catalytic properties of the imprinted film when compared to the not imprinted films and the background hydrolysis

Authors : 1) T. Mazingue, M. Lomello-Tafin, M. Passard, L. Goujon, C. Hernandez-Rodriguez, 2) J.-L. Rousset, and F. Morfin 3) J.-F. Laithier,
Affiliations : 1) Laboratoire SYMME, BP 80439, 74944 Annecy le Vieux Cedex, France 2) IRCELYON, CNRS-University of Lyon 2 avenue Albert Einstein, F-69626 Villeurbanne Cedex, France 3) Comelec SA, Rue de la Paix 129 - CH-2301 La Chaux-de-Fonds, Switzerland

Resume : Palladium Platine (PdPt) has been intensively studied these last decades due to high conversion rate in hydrogen oxidation at room temperature with significant exothermic effects (up to 250 KJ/mol). These remarkable properties have been studied by measuring the temperature variations of alumina (Al2O3) supported nanosized PdPt nanoparticles exposed to different hydrogen concentrations in dry air. This catalyst is expected to be used as a sensing material for stable and reversible ultrasensitive hydrogen sensors working at room temperature (low power consumption). Structural and gas sensing characterizations and catalytic activity of PdPt/Al2O3 systems synthesized by co-impregnation will be presented. Catalytic characterizations show that the system is already active at room temperature and sharply increases with rise in temperature. Moreover, the increase of the PdPt proportion in the co-impregnation process, improves the activity and very high conversion can be reached even at room temperature. The thermal response (about 3°C) of only 1 mg of PdPt/Al2O3 is reversible and the time response is about 5 seconds. The integration of PdPt/Al2O3 powder on a flat substrate has been realized by the deposition onto the powder of a thin porous hydrophobic layer of parylene. The possibility of using PdPt in gas sensors will be discussed.

Authors : Shinji Tamura, Ayaka Hosoya, Nobuhito Imanaka
Affiliations : Osaka University

Resume : A novel catalytic combustion-type carbon monoxide gas sensor which can operate at low temperatures was developed by employing a Pt loaded cerium oxide–zirconium oxide–tin oxide solid solution (10 wt% Pt/Ce0.68Zr0.17Sn0.15O2.0) as the CO oxidizing catalyst. Since the present catalyst was able to completely oxidize CO at the temperature as low as 65 °C, the sensor showed superior performance for the detection of CO at 70 °C which is considerably lower than that required for the operation of conventional sensors with the CO oxidation catalyst such as Pt/Al2O3 or Pd/Al2O3.

Authors : Madjid Arab1*, Nadine Dirany1, Ali Hallaoui1,2, Loic Patout1, Christine Leroux1, Jean Raymond Gavarri1
Affiliations : 1Université du Sud-Toulon Var, IM2NP, UMR CNRS 6242, BP 20132, 83957, La Garde, France 2 Université Ibn Zohr, LME, BP 32/S Agadir Maroc

Resume : In this study, we develop tungstate materials for nanostrucutre catalytic sensors systems allowing the detection of pollutant like as methane and carbon monoxide. We report the synthesis of WO3 and SrWO4 (SWO) phases, based on the coprecipitation approach. All samples were characterized by thermogravimetric analysis, X-ray diffraction and electron microscopy to identify the structure and the morphology of each compound. The catalytic reactivity of the samples was analyzed using a reactor coupled to a combined system of Fourier Transform Infrared spectrometer (FTIR) and Mass Spectrometer (MS) apparatus. The measurements were performed with different gas carriers, from room temperature to 600ºC. The catalytic activity was determined as a function of time, temperature and gases concentration. FTIR experiments show that methane given rise to two types of reactions, partial and total oxidation, at high temperature. Unlike to carbon monoxide, the oxidation occurs at a low temperature. The reactivity should be linked to oxygen species and electron exchanged with the solids. To try to connect catalytic senssing effects with charges mobility, electrical analyses have been performed. Electrical impedance measurements have been carried out on compacted polycrystalline samples, and have been interpreted with Nyquist representations.

Authors : Mauro Epifani, Elisabetta Comini, Raul Diaz, Carmen Force, Reza Zamani, Jordi Arbiol, Teresa Andreu, Pietro Siciliano, Guido Faglia, Joan R. Morante
Affiliations : Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e Microsistemi (CNR-IMM), Lecce (Italy); SENSOR Lab, Department of Information Engineering, Brescia University and CNR-IDASC, Brescia, Italy; Electrochemical Processes Unit, IMDEA Energy Institute, Móstoles, Spain; NMR Unit,Centro de Apoyo Tecnológico, Universidad Rey Juan Carlos, c/Tulipán, s/n, 28933 Móstoles, Spain; Institut de Recerca en Energia de Catalunya (IREC), Barcelona, Spain; Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Bellaterra, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Departament d’Electrònica, Universitat de Barcelona, Barcelona, Spain;

Resume : Chemoresistive gas sensing is closely connected with heterogeneous catalysis, which may provide hints for improving the sensors performances. The TiO2-supported V2O5 system is a powerful promoter of oxidation reactions of many organic compounds, hence it could be an intriguing material architecture in gas-sensing devices. The concept was that the surface vanadium oxides species could enhance the electronic exchange between the gaseous analyte and the titania support. Vanadium oxide was successfully deposited onto the surface of colloidal titania nanocrystals by wet chemical techniques. The surface modification and core doping of the titania support was shown by detailed crossed characterization techniques. The surface vanadium oxide species effectively improved the sensing properties of pure TiO2, as shown by examples of ethanol sensing. The TiO2-V2O5 sensor signal displayed much larger current variation upon ethanol injection with respect to pure TiO2. The response of the TiO2-V2O5 sensor was almost two orders of magnitude larger than for pure titania for 500 ppm ethanol concentration. The two kinds of sensors have systematically opposite behavior, with the TiO2-V2O5 response decreasing with increasing the operating temperature, contrarily to pure TiO2, indicating different reaction mechanisms in the two materials. This material typology enlarges the concept of additives, by introducing a whole new range of possible material architecture.

12:30 Lunch    
Sensors for VOC detection : Juan Daniel Prades, Universitat de Barcelona (Spain) and Michele Penza, ENEA (Italy)
Authors : Jiaqiang Xu,Nana Qian,Huimin Li, Ye Zhu,Yongheng Zhu,Yuan Zhang
Affiliations : NEST Lab, Department of Chemistry, College of Science,Shanghai University

Resume : Silica-based mesoporous organic-inorganic hybrid material modified quartz crystal microbalance (QCM) sensors have been examined for their ability to achieve highly sensitive and selective detection. Mesoporous silica SBA-15 serves as an inorganic host with large specific surface area, facilitating gas adsorption, and thus leads to highly sensitive response; while the presence of organic functional groups contributes to the greatly improved specific sensing property. In this work, we summarize our efforts in the rational design and synthesis of novel hybrid sensing materials for the detection of VOCs, including simulant nerve agent(DMMP), HCHO and BTEX, and developed high-performance QCM-based chemical sensors.

Authors : Donatella Puglisi1, Jens Eriksson1, Christian Bur1-2, Andreas Schuetze2, Anita Lloyd Spetz1, and Mike Andersson1
Affiliations : 1 Department of Physics, Chemistry and Biology, Applied Sensor Science, Linköping University, SE-58183 Linköping, Sweden; 2 Department of Mechatronics, Laboratory for Measurement Technology, Saarland University, D-66123 Saarbruecken, Germany

Resume : Here we show how iridium (Ir) or platinum (Pt) gated silicon carbide field effect transistors (SiC-FETs) can be used as highly sensitive low-cost gas sensors for the detection of volatile organic compounds (VOCs) at parts per billion (ppb) or sub-ppb levels. Gas tests were carried out at different temperatures in dry air and under effect of relative humidity (r.h.) using formaldehyde, naphthalene, and benzene as typical VOCs. The best operating conditions were found between 300°C and 330°C at a gate bias of 2V. A significant dependence on relative humidity appeared only in the case of formaldehyde, lowering the sensitivity from 45 mV/ppb (detection limit 0.2 ppb, response time 1 min) in dry air to 0.4 mV/ppb under 10% r.h. (detection limit 10 ppb, response time 12 min). Naphthalene was detected down to 2 ppb with a sensitivity of 8 mV/ppb in dry air and 5 mV/ppb under 20% r.h. (response time 8 to 6 min), whilst benzene down to 3 ppb with a sensitivity of 4 mV/ppb in dry air and 3.3 mV/ppb under 10% r.h. (response time 8 min). Surface characterization by atomic force microscopy revealed partial delamination and nanoparticle formation on the Pt-gate after exposure to VOCs, potentially responsible for performance degradation. The Ir-gated SiC-FET did not show any significant surface degradation. To get further, new sensing materials as well as smart sensing and data evaluation will be needed in order to differentiate between the VOC components.

Authors : Amadou NDIAYE1,2, Jérôme BRUNET1,2, Michele Penza3, Alain PAULY1,2, Marco Alvisi3, Christelle VARENNE1,2
Affiliations : 1Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand, France 2 CNRS, UMR 6602, Institut Pascal, F-63171 Aubière, France 3 ENEA Technical Unit of Technologies for Materials, Brindisi Research Center, I-72100 Brindisi, Italy,

Resume : Research on carbon nanomaterials for applications covering electronics devices, chemical sensors etc [1] is becoming a flourishing domain. Owing to their narrow size, carbon nanotubes (CNTs) as a new class of carbon nanomaterials present noticeable properties mainly attributed to their high surface areas and their transport properties, leading especially to tailored surface reactivity. However, because of their poor solubility, CNTs have a restricted use in many applications. This problem can be overcome by functionalisation methods [2]. The functionalization is a good way for simultaneously preserving the CNTs properties and bringing additional functionalities like gas sensitivity. In this work, CNTs have been functionalized with conjugated organic molecules like phthalocyanines (Pcs) or porphyrins (Por) derivatives for potential application in the detection of BTX (Benzene-Toluene-Xylenes). With our strategy based on dispersion technique, sensing structures based on macrocycle-CNTs hybrid materials have been processed on different transducers. This presentation will be focussed on: the functionalization of the CNTs, their characterisations (UV-Vis spectroscopy, TGA, TEM, Raman analysis) and the room temperature sensitivity of these hybrids materials towards BTX and others interfering gases. References: [1] A.G. Mamalis et. al., Prec. Eng., 2004, 28, 16. [2] D.M. Guldi, et. al., Chem. Rev. 2010, 110, 6768.

Authors : V. B. Bright, R. L. Jones, O. A. M. Popoola, M. I. Mead, I. Heimann, G. B. Stewart, R. J. North, P. H. Kaye, D. Carruthers, R. P. Baron, J. Saffell
Affiliations : Department of Chemistry, University of Cambridge, Cambridge; Department of Chemistry, University of Cambridge, Cambridge; Department of Chemistry, University of Cambridge, Cambridge; Department of Chemistry, University of Cambridge, Cambridge; Department of Chemistry, University of Cambridge, Cambridge; Department of Chemistry, University of Cambridge, Cambridge; Centre for Transport Studies, Department of Civil and Environmental Engineering, Imperial College, London; Science and Technology Research Institute, University of Hertfordshire, Hatfield, Hertfordshire; Cambridge Environmental Research Consultants, Cambridge; Alphasense Ltd, Sensor Technology House, Essex; Alphasense Ltd, Sensor Technology House, Essex

Resume : Atmospheric pollutants including nitrogen dioxide (NO2), ozone (O3), volatile organic compounds (VOCs) and particulate matter (PM) can have a significant effect on public health. As such, it is important to determine the potential exposure of individuals to these atmospheric constituents. Air quality within urban areas is highly heterogeneous in both time and space and thus characterising air pollution effectively in these environments is complex. Relatively sparse fixed site automated urban networks only provide low spatial resolution observations that do not appear adequate in detecting small scale variability. Networks of low cost sensors that utilise a variety of measurement techniques, including electrochemical, can be used to measure concentrations of a number of atmospheric species and meteorological parameters within urban areas. Equipped with GPS and GPRS to determine position and transmit data respectively, these networks have the potential to provide valuable insights into pollutant variability inherent on the local or micro-scale and to improve air pollution characterisation. This paper presents results obtained from two sensor network deployments that provide high spatial and temporal (ranging from 2 to 20s) resolution observations transmitted in near real time. The first of these deployments included measurements of CO, NO, NO2, temperature and humidity obtained from a 46 sensor nodes located in and around Cambridge. The second, deployed (40 nodes) at London’s Heathrow Airport for a period of over a year and half (2012-2013), provides additional observations of O3, SO2, VOCs, CO2 as well as size-speciated particulate matter (0.38 to 17.4 µm), wind speed and direction.

Authors : Tilman Sauerwald, Martin Leidinger, Andreas Schütze
Affiliations : Saarland University / Lab for Measurement Technology, Saarbrücken/GER

Resume : Volatile organic compounds (VOCs) are ubiquitous especially in indoor air. The level of the total VOC concentration is already an indicator for indoor air quality (IAQ), however neglecting that the health risk of various substances categorized as VOC differs a lot. Recent surveys conclude that among the great variety of substances formaldehyde, benzene and naphthalene are the top priorities for IAQ based on several investigation on occurrence and toxicity. We present a virtual sensor array for the selective detection of these three VOCs in the background of pure air and air with non-toxic VOC background. The virtual sensor is constructed using a commercial gas sensor (GGS 1000 from UST Umweltsensortechnik GmbH) with temperature cycled operation (TCO) in the temperature range from 200 °C-400 °C. Linear discriminant analysis was used to classify the different VOC. We have tested two concentrations of each VOC (formaldehyde 10 ppb and 100 ppb, benzene 0.5 ppb and 5 ppb and Naphthalene 2 ppb and 20 ppb) to reflect the relevant health risks. All tests were performed at two different humidity levels (40 %, 60 %) in pure air and with background contaminations of ethanol (0.4 ppm, 2 ppm). Despite the fact that the background concentration is much higher than the VOC concentrations, all tested VOCs could be distinguished by the virtual sensor array. Hence we proved that a virtual sensor arrays for selective VOC detection is feasible.

15:30 Coffee Break    
New Nanosensors and Sensor Concepts : Anita Lloyd Spetz Linköping University (Sweden) and University of Oulu (Finland), Michele Penza, ENEA (Italy) and Albert Romano-Rodriguez, Universitat de Barcelona (Spain)
Authors : Silke Christiansen(1,2), George Sarau(1), Sebastian Schmitt(1), M. Latzel(1), Muhammad Bashouti(1), Siegfried Waldvogel(3), Hossam Haick(4)
Affiliations : (1) Max Planck Institut for the science of light, Erlangen, Germany (2) Helmholtz-Zentrum Berlin, Berlin, Germany (3) Johannes Gutenberg Universität Mainz, Germany (4) Technion, Haifa, Israel

Resume : We will report on novel nano-patterned composite materials for molecule sensing. We rely on a wealth of nano-composites composed of silicon (Si) as well as GaN nanowires (NWs) from chemical vapor deposition (CVD) based processing including NW shaping based on reactive ion etching, plasmonic nano-structures realized by thin metal layer (silver, gold) patterning with focused ion beam microscopes as well as few layer graphene from CVD processing. The NWs show large surface areas that can chemically be functionalized to account for sensing functionality. The graphene requires proper chemical treatment to permit attachment of functional groups. The chemical routes to nano-materials functionalization will be reported. Sensing mechanisms with functional nano-materials can be e.g. of electrical, optical or mechanical nature. Examples will be given for all 3 cases. Emphasis will reside on optical detection based on the surface-enhanced Raman scattering (SERS) effect. We will report SERS of graphene layers transferred on arrays of split ring resonators (SRRs). Raman enhancement factors per area up to 75 demonstrate the strong plasmonic coupling between graphene and the metamaterial resonances. The SRR/graphene material offers a perspective to controlling SERS and may pave the way towards advanced SERS substrates that could lead to the detection of single molecules attached to graphene for bio-chemical sensing.

Authors : J. Samà1, S. Barth2, J.D. Prades1, M. Seifner2, O. Casals1, I. Gracia3, J. Santander3, C. Calaza3, L. Fonseca3, C. Cané3, A. Romano-Rodríguez1
Affiliations : 1 MIND-IN2UB-Dept. Electronics, Universitat de Barcelona (UB), Martí i Franquès 1, 08028, Barcelona, Spain; 2 Institute of Materials Chemistry, TU Wien, Getreidemarkt 9/165, A-1060 Vienna, Austria; 3 Institut de Microelectrònica de Barcelona, IMB-CNM-CSIC, 08193 Bellaterra, Spain

Resume : Germanium (Ge) is a classical semiconducting material that constituted the substrate for the invention of the bipolar transistor, but due to its low abundance at the earth crust it is only sparsely used for certain applications. However, recently, there is a growing interest on Ge nanowires (NW) because they overcome electrical and optical properties of silicon. In this work we present for the first time, to the best of our knowledge, the development and gas test of Ge nanowire based chemoresistive gas sensors. For this, we have locally, site-specifically and energy and material efficiently grown NWs using the VLS method on the top of micromembranes equipped with surface interdigitated electrodes and a buried heater. Similarly to other chemiresistors, the GeNW surface reacts with the presence of reducing and oxidizing gases, what causes a change in its resistance. A drawback of Ge is, unlike silicon, a non uniform and non stoichiometric GeOx layer is formed, whose thickness can be limited by working in a low temperature range. Ge NWs based sensors have shown good response towards the presence hundred of ppb’s of NO2 and CO even at room temperature. The fabricated device provides a functional sensor which consumes few mW for both heating and measuring. The behavior of the Ge NW gas sensor will be presented and the possibilities for improvements of its properties through surface functionalization will be discussed.

Authors : S. Thomas, F.H. Villa-Lopez, W. Ludurczak, M. Cole and J.W. Gardner
Affiliations : University of Warwick, UK

Resume : As part of a study into environmental air quality monitoring, an acoustic wave based sensor has been designed, modelled and developed for airborne particulate matter detection (PM10, PM2.5, UFP). The particle detectors have been designed using Surface Acoustic Wave (SAW) sensors and bulk acoustic Solidly Mounted Resonator (SMR) sensors; both operating in the high frequency domain (above 0.8 GHz). Initial experiments using SAW sensors for the detection of sub-micron sized particles have been performed, proving the effectiveness of acoustic sensors in the detection of ultrafine particles (UFP) as the acoustic penetration depth determines the size of particle to be sensed. Furthermore, a COMSOL multiphysics based Finite Element Method (FEM) model has been developed in order to determine the frequency response of these particle sensors and investigate the effects of the device geometry, materials used, and particle loadings. It is evident from our FEM analysis that an 840 MHz SMR sensor is capable of detecting ultrafine nanoparticles with masses in the femtogram range; it gives a frequency shift of few megahertz, has good stability, and mass sensitivity of ca. 10 kHz/pg. We believe that airborne particle size and count could be determined by employing a tailored design of our bulk acoustic resonator, thereby enabling a fully integrated, smart CMOS-based particle sensor capable of the real-time, ubiquitous monitoring and low-cost monitoring of airborne particulates.

Authors : Lorenzo Maserati, Iwan Moreels, Roman Krahne, Liberato Manna, Yang Zhang
Affiliations : Italian Institute of Technology (IIT), Via Morego 30, 16163 Genoa, Italy

Resume : Colloidal nanocrystals are nanomaterials synthesized by wet chemical methods (typically by hot injection technique) in coordinating solutions1. These materials are intriguing, because their physical properties, such as electronic structure, optical and magnetic properties, can be tuned by changing the size or shape of the nanocrystals2. On the other hand, the large surface-to-volume ratio associated with the nanocrystals opens the opportunity of tweaking their properties through surface engineering. In this work, we report on the effect of surface oxygen adsorption on the photoconductivity of CdS nanocrystal films. The photocurrent-voltage (PIV) characteristics reveal: 1) a significant reduction of the photocurrent when the surface of the CdS nanocrystals is adsorbed by oxygen; 2) the improvement in the linearity of the PIV curves upon oxygen adsorption. A model based on the energy band bending upon oxygen adsorption is proposed to understand these results. In addition, the photoluminescent emissions of intrinsic band and trap states show significant enhancement in the presence of oxygen. Furthermore, we investigate the voltage bias and light intensity dependence of the transient photocurrent response of our devices in dry air and Ar. Eventually, the sensing dynamics of our devices toward different concentration of oxygen is assessed. The maximum sensitivity achieved against the 10% oxygen is ~ 35 at room temperature. Our work clarifies the mechanism of photo-transport through CdS nanocrystal films upon oxygen adsorption and sheds light on exploring these devices for realistic applications. (1) S. Deka et al, J. Am. Chem. Soc., 2010, 132, 8912. (2) R. Krahne et al, Phys Rep 2011, 501, 75.

Authors : Marti Gich,1 Cesar Fernandez-Sanchez,2 Cosmin Cotet,3 Pengfei Niu1 and Anna Roig1
Affiliations : 1Institut de Ciencia de Materials de Barcelona, ICMAB (CSIC), Campus UAB, 08193 Bellaterra, Spain 2Institut de Microelectronica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193-Bellaterra, Spain 3Faculty of Chemistry and Chemical Engineering, Babes Bolyai University, 400028 Cluj-Napoca, Romania

Resume : Most research in the field of analytical tools for the detection of heavy metal is aiming at the development of sensors that can provide fast, real-time, minimum maintenance on-site measurements carried out by non-specialists. Sensors should also provide the possibility to decrease the detection limits, enhance the sensitivity levels and widen the range of target analytes that can be measured. In this context, cost-effective mercury-free electrochemical sensors have recently been the focus of research showing the potential of these devices and their huge market potential. We have adopted an innovative approach to prepare carbon-bismuth nanoparticle composites using sol-gel chemistry1. The potential of the as-obtained materials in the analysis of heavy metals in aqueous solutions is demonstrated by the simultaneous detection of several heavy metal ions (Pd, Cd, Zn, Ni) at concentration levels (under ppb) below the limits targeted by the most stringent drinking water regulations and using short accumulation times of just 120 s. We will describe the fabrication and characterization of the composites and discuss the advantages and prospective developments for such sensors. 1Gich et al., J. Mater. Chem. A, 2013, 1, 11410

Authors : J.-M. Suisse[1], M. Mateos[1], P. Gaudillat[1], M. Bouvet[1], J. Fouchet[2], L. Douce[2]
Affiliations : [1]Institut de Chimie Moléculaire de l’Université de Bourgogne (ICMUB), Université de Bourgogne, UMR CNRS 6302, 9 avenue A. Savary, F-21078 Dijon, France; [2]Institut de Physique et Chimie des Matériaux de Strasbourg, UMR, DMO, CNRS-Université de Strasbourg, Strasbourg, France

Resume : The air we breathe at home, outdoors and on our work location is at the center of many debates and the source of increasing concerns. It contains numerous harmful substances resulting from human activities that are found in various amounts depending on their nature and on the context (location, weather, etc.). Monitoring air quality is a flourishing business with increasing requirements. In particular, enforcing ever restricting laws and regulations requires more efficient and reliable sensors that can operate with greater accuracy. Eventually democratizing these sensors will only be possible by lowering their production costs. In this context, the sensors we present are cheap conductometric devices built around an MSDI heterojunction (recently patented) capable of detecting and quantifying ammonia even under humid atmosphere. These sensors are made of two thin layers of molecular materials deposited onto comb-shaped electrodes. The sensors are small-sized (1cm2), energy-efficient (1 µW) and cost effective. The MSDI sensors we report are built using either an n-type molecular semiconductor or an ionic compound as sub-layer and a p-type intrinsinc molecular semiconductor as top-layer. These sensors were successfully tested for ammonia concentrations in the 10–90 ppm range under 10–70 % RH. They exhibit a stable response to ammonia and a low current drift, nearly independent from the moisture level.

Authors : B.Medina-Rodriguez(1,2), G.Vescio(2), E.Xuriguera(2), A.Varea(2), O.Casals(2), F.Ramos(1), A.Cirera(2)
Affiliations : (1)FAE- Francisco Albero S.A.U., Rafael Barradas 19, L’Hospitalet de Llobregat 08908, Spain; (2)MIND/IN2UB Electronics Dept., University of Barcelona. Martí i Franqués 1, Barcelona 08028, Spain

Resume : Flexible electronic devices are attracting much interest in gas sensor field due to their capability to be implemented in a wide range of applications. This work presents a flexible self-heating and low-powered gas sensor platform fabricated by means of inkjet- and screen- printing as well as a further study of its performance and aging. Silver has been used as the conductor for the printed electrodes and the heater and polyimide as the substrate. The performance of screen- and inkjet- printed devices has been compared, and their reliability has been proved by long-term lifetime characterization and by salt spray aging. Furthermore, the heater design has been optimized according to their consumption. Taking into account that silver quickly oxidizes and this process is magnified as the temperature increases, the long-term characterization has been done holding the voltage applied at an initial self-heating temperature of 120ºC. Chemical degradation in inkjet-printed heaters is negligible compared to those with screen-printed circuitry, whose porosity is notable, as it is shown by SEM/EDS. To prevent the atmosphere degradation induced by the increase of temperature, the heater has been buried by an adhesive polyimide tape. Protected devices lengthen their lifetime more than three times the un-protected ones, showing no degradation after 350h of continuous operation at 120°C. The heater design was also optimized for low powered and long-term performance. Power consumption has been reduced to 150mW for 140°C for protected inkjet-printed heaters. This novel flexible-platform has been implemented with deposited carbon-based materials as the gas sensing material, by means of electrospray technique. The exit of this system has been proved by measuring different gases such as NH3, NO2 and humidity.

Authors : Hossam Haick
Affiliations : The Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion ? Israel Institute of Technology, Haifa 3200003, Israel

Resume : We have developed an ultra-sensitive, multi-parametric touch (or pressure) flexible sensors based on monolayer-capped nanoparticles (MCNPs). These sensors can be produced through SINGLE fabrication step and can be operated under low power consumption (0.5 V) and extreme environmental confounding factors (e.g., high humidity levels and contaminants in the atmosphere). On top of these attributes, we were able to build an MCNP-based prototype allowing simultaneous detection and monitoring of multiple environmental parameters of touch (or pressure), humidity, and temperature. These devices have shown the ability to decouple between the various stimuli (e.g., pressure, temperature, and humidity) that exist in a complex mixture and/or environment, which, so far, represents a critical challenge for these multi-parametric sensors. Indeed, these multi-parametric sensors have shown abilities to sense temperature with resolution higher than 1 ?C and average error of ~5%, relative humidity with resolution higher than 1% RH and average error of ~2% and pressure/touch with a resolution of 0.2gr. Overall, these sensors have shown excellent potential for future robust, simple, large-area, cost-effective and easy-to-fabricate bendable and stretchable sensing systems that can be utilized in a wide variety indoor and outdoor environmental monitoring applications.

18:30 Gathering of Day    
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09:30 COST Action TD1105 - 5th MC Meeting - Part I    
11:00 Coffee Break    
11:30 COST Action TD1105 - 5th MC Meeting - Part II    
13:00 Light Lunch    
14:00 End of Symposium B