Materials for electronics and optoelectronic applicationsH
Flexible electronic sensors
Introduction and scope:
This symposium is focused on flexible electronic sensors (FES). A wide variety of these devices has been proposed in last few years, based on different materials (organic semiconductors, oxides, graphene, etc), and technologies and aimed at different applications. However, a gap must be filled in order to employ them in future real applications: this gap concerns the full comprehension of the physical mechanisms ruling the performance and reliability of these devices and the full exploitation of the nano-material properties in a device perspective. The latest advances in fabrication, characterization, device physics and innovative applications of FES will be presented.
The symposium aims at bringing together leading scientists from a variety of backgrounds (chemistry, physics, engineering and material science), involved in forefront fundamental and applied research on Flexible Electronic Sensors, covering materials, device fabrication, various working principles and modeling that reveal the intrinsic potential of these devices.
Small-molecules and polymeric organic semiconductors are among materials widely used for developing these devices, together with semiconductor oxides, and more recently graphene, promising the development of novel electronic devices such as flexible inexpensive sensor systems and innovative molecular sensors. Considering the rapid progress in the applied research on electronics based on alternatives to silicon and inorganic crystalline materials, as organic, oxide semiconductors, graphene, etc. chemical and physical sensors seem to be a very attractive field with a huge potential of becoming a killer application for this kind of technologies. Thus it is very interesting to gather together the main researchers in this field in order to identify which will be the main milestones of the future roadmap. In particular, combining the nano-scale (material properties) with the micro-scale (device) is still challenging as it requires a full comprehension of the device physics and of the material interfaces.
Hot topics to be covered by the symposium:
- novel materials synthesis
- novel device architectures
- novel sensing applications
- device modelling
- device biasing and readout circuitry
- sensor systems
Tentative list of invited speakers:
Section I – Bioelectronics
- S. Ingebrandt, Hochschule Kaiserslautern, Germany
- Jouko Peltonen, Center of Excellence for Functional Materials, Åbo Akademy University, Finland
Section II – Electronic Sensors
- M. Ramuz, Ecole Nationale Supérieure des Mines de Saint Etienne, France
- Eric Daniel Glowacki, Johannes Kepler University, Linz, Austria
Section III – Non organic Sensors
- Keon Jae Lee, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Republic of Korea
- Jürgen Steimle, Saarland University, Multimodal Computing and Interaction, Saarbrücken, Germany
Section IV – Graphene and Carbon Nanotubes
- Satria Bisri, Emergent Device Research Team, Supramolecular Chemistry Division, Riken Center for emergent matter science (CEMS), Japan
Section V – Novel Applications
- R. Nawrocki, Department of Electrical Engineering and Information Systems, University of Tokyo, Japan
- M. Kaltenbrunner, Interface Culture Lab University of Art and Design, Linz, Austria
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Bioelectronics : Roisin Owens
Authors : Felix Hempel1,2, Jessica Ka-Yan Law2, Ruben Lanche1, Anna Susloparova1, Vivek Pachauri1 and Sven Ingebrandt1
Affiliations : 1 Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, Zweibrücken (Germany) 2 RAM Group DE GmbH, Research and Development Center Germany, Amerikastr. 15, Zweibrücken
Resume : Printable electronic sensors gained a lot of attention in recent years in the field of cell-based biosensors. Their versatility in combination with easy fabrication methods and their extremely high biocompatibility made those devices a new and exciting topic for cell sensing applications. We followed 2 directions to enable a new generation of cell-based sensors as alternative to metal microelectrode arrays (MEA) or silicon-based field-effect transistors (FET). Electrochemically-gated transistors (ECTs) out of poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) are interesting since these devices offer a completely novel gating and signal recording mechanism compared to the classical, purely capacitive coupling of cells to MEAs and FETs. Another interesting class are carbon-based sensors and sensors made of chalcogenide materials such as MoS2. They offer extremely high carrier mobilities and a large sensitivity to interface cells in potentiometric, amperometric and impedimetric configurations. We realized several wafer-scale fabrication processes for the above-mentioned materials on silicon and glass as well as on flexible, polymeric substrates. These devices were characterized using state-of-the-art surface characterization and electronic measurement tools and exhibit excellent sensor characteristics with transconductance values exceeding conventional silicon-based FETs. A major challenge was the stabilization of the materials for longer cell culture periods. We present first results of recordings from cardiac myocytes and from individually adhering cell lines, with a promising performance in cell-based assays. In future these devices could be so cheap that disposable sensors embedded in standard plastic cell culture dishes would be possible, which could be a very interesting alternative to the classical sensor types in cell-based biosensors.
Authors : M. R. Antognazza, Giovanna Barbarella, C. Tortiglione, G. Pertile, F. Benfenati, Guglielmo Lanzani
Affiliations : Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Pascoli 70/3, 20133 Milano, IT; Institute of Organic Synthesis and Photoreactivity, National Research Council of Italy, Via Piero Gobetti 101, 40129 Bologna, IT; Istituto di Scienze Applicate e Sistemi Intelligenti "E.Caianiello", National Research Council of Italy, Via Campi Flegrei 34, 80078 Pozzuoli, IT; Ophthalmology Operative Unit, Sacro Cuore Hospital - Don Calabria, Negrar, IT; Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, IT; Department of Physics, Politecnico di Milano, P.zza L. da Vinci 32, 20133 Milano, IT
Resume : Use of light for selective and spatio-temporally resolved control of animal specific functions is emerging as a valuable alternative to standard electrical methods, able to overcome many current limitations. Several strategies have been proposed, mainly exploiting photoactive mediators nearby or within the animal tissues: photo-isomerizable or photo-cleavable compounds, infrared neural stimulation, genetic expression of sensitive probes. Here, we propose the use of organic semiconductors as efficient, versatile and biocompatible optical transducers, suitable for in vivo applications. In more detail, we report on poly-hexylthiophene (P3HT)-based materials in form of (a) thin films; (b) nanoparticles. (a) We fabricated a fully flexible, organic retinal prosthesis made of conjugated polymers layered onto a silk fibroin substrate. The long-term biocompatibility was extensively assessed by implanting the device in the sub-retinal space of rat animal models. Moreover, electrophysiological and behavioral analyses revealed a significant and persistent recovery of light-sensitivity and visual acuity up to 6 months after surgery. (b) We synthesized P3HT nanoparticles, with excellent colloidal stability in aqueous solution and optimal in vitro bio-compatibility. We then explored their use as photo-actuators in animal models of Hydra Vulgaris. We show that uptake of organic nanoparticles leads to specific light-activated effects, on both a behavioral and a molecular level. Possible photo-stimulation mechanisms will be critically discussed.
Authors : Eleonora Macchia, Domenico Alberga, Kyriaki Manoli, Giuseppe F. Mangiatordi, Maria Magliulo, Gerardo Palazzo, Francesco Giordano, Gianluca Lattanzi, Luisa Torsi
Affiliations : Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro - Bari (Italy); Dipartimento Interateneo di Fisica “M. Merlin” dell’Università e del Politecnico di Bari and INFN - Bari (Italy); Dipartimento di Farmacia – Scienze del Farmaco, Università degli Studi di Bari Aldo Moro - Bari (Italy); Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi di Foggia and INFN - Foggia (Italy); Center for Colloid and Surface Science (CSGI) – Bari (Italy)
Resume : The study of proteins confined on a surface has attracted a considerable attention due to its relevance in the development of bio-systems for laboratory and clinical settings. To this aim, organic bio-electronic platforms can be used as tools to achieve a deeper understanding of the processes involving protein interfaces, since the energetic and electrostatic contributions play the main role in shaping the device response. Three different biotin-binding proteins have been integrated in an organic thin-film transistor (TFT) to investigate the changes occurring in the protein-ligand complex morphology and dipole moment. To this end, functional bio-interlayer and the newly introduced pre-formed complex TFTs have been proposed to separately address these two features. This has been achieved by decoupling the output current change upon binding, taken as the transducing signal, into its component figures of merit. In particular, the threshold voltage is related to the protein dipole moment, while the field-effect mobility is associated with conformational changes occurring in the proteins of the layer upon ligand binding, directly impacting on the transport properties of the organic semiconductor. Molecular Dynamics simulations on the whole avidin tetramer in presence and absence of ligands were also carried out, to evaluate how the interactions with the ligand affect the protein dipole moment and the conformation of the loops surrounding the binding pocket. References 1. Macchia, E.; Alberga, D.; Manoli, K.; Mangiatordi, F.G.; Magliulo, M.; Palazzo, G.; Giordano, F.; Lattanzi, G.; Torsi, L.; Scientific Reports 2016, in press.
Authors : Silvia Conti, Carme Martinez-Domingo, Stefano Lai, Piero Cosseddu, Eloi Ramon, Annalisa Bonfiglio
Affiliations : Silvia Conti (Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, Italy); Carme Martinez-Domingo (Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Barcelona, Catalonia, Spain); Stefano Lai (Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, Italy); Piero Cosseddu (Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, Italy); Eloi Ramon (Institut de Microelectrònica de Barcelona, IMB-CNM (CSIC), Barcelona, Catalonia, Spain); Annalisa Bonfiglio (Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, Italy)
Resume : Organic Thin-Film Transistor (OTFT) based sensors have been so far proposed in literature, but several technological drawbacks still limit the actual exploitation of the potentialities of organic electronics in the field of biomedical engineering and biorobotics. For instance, Organic Field-Effect Transistors (OFETs) are typically biased at high voltages (tens of volts), which are not suitable for biological environments. So far, low voltage devices are generally obtained by using ultra-thin dielectrics, which are deposited by conventional techniques, such as spin coating or physical vapor deposition. Therefore, a reliable fabrication process for low voltage OFETs with large area techniques is substantially missing. Inkjet printing is a flexible, versatile and low-cost technique which doesn’t require tooling, masks or screens. To overcome these issues an inkjet OFET based sensor is proposed. This device can be fabricated on flexibles substrates which require low temperatures and can be easily adapted to mass fabrication processes. The developed sensor is based on BGBC (Bottom Gate Bottom Contact) transistor with an insulator overlayer. Our work relies on the detection of the charged species thanks to the coupling effect of the insulator/biomolecules overlayer. In comparison to TGBC (Top Gate Bottom Contact) devices, the main advantage of this dual-gate approach is the fact that sensor can be switched on from the bottom gate avoiding the polarization of the device through the electrolyte which is not convenient for the functionality of the biomolecules. Furthermore, thanks to the thin inkjet printed bottom dielectric layer, low voltages are used.
Authors : Corrado Napoli, Stefano Lai, Ambra Giannetti, Sara Tombelli, Francesco Baldini, Massimo Barbaro, Annalisa Bonfiglio
Affiliations : Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, Italy; Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, Italy; Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Sesto Fiorentino, Italy; Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Sesto Fiorentino, Italy; Istituto di Fisica Applicata “Nello Carrara”, Consiglio Nazionale delle Ricerche, Sesto Fiorentino, Italy; Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, Italy; Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, Italy;
Resume : In this work, a Field-Effect Transistor-based sensor, namely OCMFET, is integrated with a particular DNA probe, namely Molecular Beacon (MB), for DNA hybridization detection. MBs have a peculiar hairpin shape, composed by a single stranded loop and a double stranded stem. The conformational constraint of these probes results in improved selectivity, thus allowing high accurate discrimination of alleles and single nucleotide polymorphisms. Such a probe is therefore interesting for screening genetically diverse species and developing drugs through pharmacogenetic applications. Here, we exploit the OCMFET working principle for a label-free detection of MBs hybridization with complementary probes. The OCMFET is a floating gate transistor capable to detect biochemical species by means of their intrinsic charge. As DNA is negatively charged, hybridization modulates the charge distribution in the floating gate, thus causing a variation of the transistor output current. Different tests were carried out to demonstrate the feasibility of the proposed approach. OCMFET capability to detect hybridization of MB with its target was tested and validated by means of fluorescence microscopy, as the employed probes are conjugated with a fluorophore and a quenching dye whose distance is modulated by the hybridization. Real-time recording of the transistor current was performed, demonstrating a distinguishable dependence of current variations to the target concentration employed for hybridization.
Authors : Jouko Peltonen(1), Emil Rosqvist(1), Anni Määttänen(1), Jawad Sarfraz(1), Helka Juvonen(1), Markus Pesonen(2), Ronald Österbacka(2), Petri Ihalainen(1)
Affiliations : (1) Laboratory of Physical Chemistry, Centre for Functional Materials, Åbo Akademi University, Porthansgatan 3-5, FI-20500 Åbo, Finland; (2) Physics, Center for Functional Materials, Åbo Akademi University, Porthansgatan 3-5, FI-20500 Åbo, Finland
Resume : Research in the field of paper electronics has made significant progress during the recent years . Tailored paper grades  have enabled controlled printing of various functional inks for different functions. Printed patterned arrays in combination with printed electronic components have given rise to the development of test platforms for various optical indicators, electronic and electrochemical sensors and screening assays [3, 4]. Ultrathin metal electrodes can be prepared by vapour deposition. The adhesion of such electrodes onto a paper substrate can be improved by an additional latex top coating. The latex film including the electrodes can be peeled off, yielding a self-supporting structure which is semi-transparent . Latex coatings can also be fabricated on e.g. AFM calibration grids, yielding semi-transparent and hierarchically structured self-supporting films. These polymeric films offer a good adhesive support for biomolecules, facilitating the introduction of passive and active components for e.g. continuous electrochemical monitoring of glucose levels, pH, ion concentrations, antibody-antigen binding and DNA hybridization. References 1. D. Tobjörk, R. Österbacka, Advanced Materials 23 (2011), 1935-1961. 2. R. Bollström et al., Organic Electronics 10 (2009), 1020-1023. 3. A. Määttänen et al., Sensors and Actuators B 160 (2011), 1404-1412. 4. P. Ihalainen et al., Biosensors 3 (2013), 1-17. 5. A. Määttänen et al., Applied Surface Science 364 (2016), 37-44.
Authors : Isacco Gualandi1, , Marco Marzocchi1, Andrea Achilli1,2, Annalisa Bonfiglio2, Marta Tessarolo1, Beatrice Fraboni1
Affiliations : 1 Department of Physics and Astronomy, University of Bologna, Bologna, Italy 2 Department of Electrical and Electronic Engineering, University of Cagliari, Cagliari, Italy
Resume : A tremendous and growing interest is focused on the development of new wearable technology for physiological monitoring, in order to obtain a novel class of personalized point-of-care devices that could be integrated into the daily life of a patient in the form of wireless body sensors. Although most of the research efforts are converged on the production of miniaturized wearable appliances based on relatively mature technologies, such as motion tracking, a remarkable ability would be the chemical sensing of bio-markers in body fluids. Several wearable sensors, mainly based on an electrochemical transduction, have been developed, however they often require the implantation of electrodes and the use of a relative-bulky read-out electronics. To overcome these drawbacks a good solution is the monitoring of biomarkers in sweat through wearable sensors that are merged with the textile, obtaining a device that really “disappears” inside the cloth. Recently, the potentiality of textile Organic electrochemical transistors (OECTs) for the detection of ions and adrenaline has been shown [Coppedè et al., J. Mater. Chem. B, 2 (2014) 5620], but the sensing process should be studied in depth in order to control and fully exploit their properties and performance . This contribution reports on the huge potential of OECTs as wearable chemical sensors for the detection of bio-compounds in sweat. In an OECT the current flowing in the channel (a stripe of conductive polymer) can be modulated through the voltage applied to the gate electrode by electrochemical reactions that take place in an electrolytic solution. Since the device is the combination of a sensitive element and an amplifier, OECTs directly amplify the electro-chemical signals. These transistors are made by screen printing on different textiles and they exhibit very appealing features for wearable sensors: 1) the operating potentials are very low (< 1 V), a key point considering that the device must be placed in direct contact with skin; 2) since the current used as signal is quite high ( 1 mA), it requires a simple readout electronics ; 3) the absorbed power is very low ( 10-4 W); 4) it can be deformed without observing a degradation of its electrical features. Moreover the stability of the OECT we have developed has been assesed under washing conditions. The potentialities of the here described OECT as a sensor were tested using different redox active bio-molecules (adrenaline, dopamine and ascorbic acid). All tested analytes react with PEDOT:PSS by extracting charge carriers from the transistor channel and leading to a logarithmic decrease of the drain current for increasing concentration. The OECTs sensing capability has been assessed in two different experimental contexts: i) totally dipped in an electrolyte solution, to evaluate their performance in the ideal operation; ii) in air, by sequentially adding few drops of electrolyte solution in the sensing area in order to simulate the exposure of the fabric to human sweat in real applications.
Poster session : Beatrice Fraboni
Authors : Wang Gyu No*, Dong Cheul Han**, Si Ok Ryu*
Affiliations : Yeungnam University*, Gumi Electronics and Information Technology Research Institute (GERI)**
Resume : Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a conductive material and it exhibits a good sensitivity to ammonia gas. The positively charged PEDOT:PSS leads to the variation of its electrical properties like conductivity and resistance when it contacts with ammonia gas acting as electron donor in the sensor. In this study, the PEDOT:PSS films were deposited on the soda lime glasses using spin coating method with four different solvents and then the sensors were fabricated with silver electrodes on the deposited films. Influence of solvent on the conductivity and effects of film thickness, annealing temperature, and solvent annealing on the sensitivity of PEDOT:PSS to ammonia were investigated to maximize the sensor performance. The conductivity of sensors was measured by a four point probe in dry condition and their sensitivity was measured by a high-end multimeter in a sealed test cell filled with ammonia gas in the range of 5~200 ppm. The sensors prepared with ethylene glycol, which was used as a solvent, exhibit about 106 times higher conductivity per unit area than the other solvents. Depending upon the film thickness and the annealing temperature, the sensitivity of the fabricated sensors was varied in the range of 4%~12% and 19%~36%, respectively. It was confirmed that the performance of PEDOT:PSS was enhanced not only by optimizing the film thickness and the annealing temperature but also by choosing the solvent.
Authors : Giulio Rosati, Matteo Scaramuzza, Elisabetta Pasqualotto, Alessandro De Toni, Carlo Reggiani, Alessandro Paccagnella
Affiliations : Giulio Rosati, Elisabetta Pasqualotto, Alessandro Paccagnella; Department of Information Engineering, University of Padova, via G. Gradenigo 6/b, 35131, Padova, Italy Matteo Scaramuzza, Elisabetta Pasqualotto, Alessandro De Toni; ARC- Applied Research Center s.r.l., via J. da Montagnana 47, 35131, Padova, Italy Carlo Reggiani; Department of Biomedical Sciences, University of Padova, via U. Bassi 58, 35131, Padova, Italy
Resume : The importance of flexible sensors in both clinical and personal care applications is constantly growing due to their comfort, and compatibility with body movements. Lactate in human fluids has a great importance in a wide variety of applications, e.g., in medical and sport practice. Therefore, the possibility to monitor lactate concentration using wearable electrochemical sensors interfaced to a portable system, e.g., smartphones or fitness tracker, is very attractive. However, this goal requires the development of sensing materials which can be easily fabricated on flexible substrates, with sufficiently stable features to bear the continuous electrochemical and mechanical stresses. At the Biodevices Lab of the University of Padova, we are currently developing an inkjet method to print electrodes on both paper and flexible polymers, for the implementation of an electrochemical lactate sensor. This sensor is based on the Lactate Dehydrogenase (LDH) enzyme, which produces NADH in presence of lactate. The sensor quantifies the NADH concentration, and thus the lactate concentration in the initial sample. The sensitivity of the sensor depends on the electrodes' materials, which should be able to reduce the interferences of other compounds in the samples. Therefore, we are currently testing the electrochemical and surface properties of inkjet-printed carbon and silver electrodes, obtaining a resistivity below 0.14 Ω/sq and a stable EIS spectra over time in different electrolytes.
Authors : Jeong Hui Lee, Dong Hyun Lee*
Affiliations : Department of Polymer Science and Engineering, Dankook University, 152, Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do, 448-701, Korea.
Resume : In this study, we report a unique method to fabricate silver networks embedded in cracks of polymer surfaces for a highly transparent and conducting electrode. A brittle layer on a poly(dimethyl siloxane) (PDMS) substrate was first generated by UV/Ozone treatment. Then, uniform cracks were produced by bending the substrates with various strains. In particular, the periodic distance of cracks could be precisely controlled by varying bending strains. For electrically conductive structures, silver nanoparticle-based conductive inks were filled into the cracks by sliding a cover glass followed by thermal curing. Electrical and optical properties of the samples were characterized by measuring current-voltage curve and UV-Vis spectroscopy. The embedded silver networks were finally utilized as a transparent and flexible electrodes to fabricate AC voltage-driven electrochemiluminescent (ECL) devices.
Authors : Tobias Cramer, Lorenzo Travaglini, Stefano Lai, Luca Patruno, Stefano de Miranda, Annalisa Bonfiglio, Piero Cosseddu, Beatrice Fraboni
Affiliations : Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Italy; Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Italy; Department of Electric and Electronic Engineering, University of Cagliari, Piazza d’Armi, Italy; DICAM, University of Bologna, Viale Risorgimento 2, Italy; DICAM, University of Bologna, Viale Risorgimento 2, Italy; Department of Electric and Electronic Engineering, University of Cagliari, Piazza d’Armi, Italy; Department of Electric and Electronic Engineering, University of Cagliari, Piazza d’Armi, Italy; Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Italy
Resume : Reliable performance under mechanical deformation is a central goal for flexible electronic sensors. The realization of mechanically rugged materials and device architectures depends crucially on the understanding of how strain affects electronic material properties and leads to defect formation. Scanning Kelvin-Probe Microscopy (SKPM) is a formidable technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that KPFM becomes feasible on free-standing, deformed flexible samples when operated in the low-interaction regime of non-contact mode thereby providing the opportunity to study strain effects on nano-electronic properties. As an example we apply the technique to investigate strain effects and failure of flexible thin film transistors containing TIPS-pentacene during bending. We find that the step-wise reduction of device performance at a critical bending radii is related to the formation of nano-cracks in the microcrystal morphology of the TIPS pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects. We support our findings by numerical simulations of the bending mechanics of the hole transistor structure allowing to quantify the tensile strain exerted on the TIPS-pentacene micro-crystals as the fundamental origin of fracture.
Authors : Cristiane Margarete Daikuzono, Larisa Florea, Colm Delaney, Henok Tesfay, Aoife Morrin, Dermot Diamond and Osvaldo Novais De Oliveira Junior.
Affiliations : Insight Centre for Data Analytics, National Centre for Sensor Research, Dublin City University, Dublin, Ireland; Instituto de Física de São Carlos, Universidade de São Paulo, Brasil.
Resume : Here we report a novel sensor, which may have great potentials for the fabrication of low-cost, wearable devices for the detection of monosaccharides (e.g. glucose, fructose) using electrical impedance spectroscopy. The sensor is composed of functionalised carbon interdigitated electrodes (IE) printed on paper. The IE are 10 mm x 15 mm and have 10 digits of 1 mm in width and 7 mm long, and were printed on paper using screen-printing technique. After printing, the electrode surface was modified with a thin hydrogel layer made of a copolymer of acrylamide and 3-(Acrylamido)phenylboronic acid (PBA) in a ratio of 5:1. PBAs are well known for their strong, reversible interactions with diol-containing compounds like sugars (e.g. glucose and fructose)3 making them compounds of choice for the development of a wide range of sensors and biosensors1-3. In this context, we investigated the capacitance and impedance variations with different concentration of glucose and fructose (5-50 mM) present in the phosphate buffer aqueous solution. The electrical measurements were made using Solartron 1260. 20 mV was applied and the impedance was analyzed in a frequency range of 0.1 – 10 MHz. Impedance results show a decrease of impedance values with increasing sugar concentration due to less resistivity to electrical current. The results indicated that the 20 mol % PBA hydrogel swells more when in contact with fructose solution than glucose when the same concentrations of the sugar were employed. This could potentially be used to differentiate between the different sugars present in solution. Future work will focus on the incorporation of these modified carbon printed electrodes in to wearable skin patch type platforms for non-invasive sugar monitoring in sweat. References (1) Guan, Y.; Zhang, Y. Boronic acid-containing hydrogels: synthesis and their applications. Chem.Soc.Rev. 2013, 42, 8106-8121. (2) Cambre,J.n.; Sumerlin, B.S. Biomedical applications of boronic acid polymers. Polymer. 2011, 4631-4643. (3) Zhang, C.; Losego, M. D.; Braun, P. V. Hydrogel-Based Glucose Sensors: Effects of Phenylboronic Acid Chemical Structure on Response. Chem. Mater. 2013, 25, 3239–3250. Email: email@example.com
Authors : Stefano Lai, Massimo Barbaro, Annalisa Bonfiglio
Affiliations : Stefano Lai - Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, ITALY; Massimo Barbaro - Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, ITALY; Annalisa Bonfiglio - Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari, ITALY;
Resume : In this abstract, the peculiar advantages of a field-effect transistor (FET) based sensing structure, namely Organic Charge-Modulated Field-Effect Transistor (OCMFET), are discussed. OCMFET is based on a floating gate organic FET (OFET) device which can be used as charge sensor. Therefore, biochemical reactions that produce a charge variation/modulation in the near proximity of a sensing area (a part of the floating gate directly exposed to the environment) can be detected by the OCMFET and transduced as variation in the transistor output current. The OCMFET has peculiar characteristics among OFET-based biosensors (bioFETs): the organic semiconductor is physically separated from the sensing area, thus making transduction not reliant on its choice and allowing its encapsulation for enhanced device lifetime. Furthermore, with respect to other sensing structures, a reference electrode imposing the potential in the measurement solution is not needed. Here, we will focus on two features that make OCMFET approach unique among bioFETs: i) the capability of precisely tailor the sensing performances of the device by acting on geometrical parameters in the sensor layout, and ii) the capability of detecting biochemical reactions also when high ionic strength solutions are employed. DNA hybridization will be considered as testbench, demonstrating that its detection is possible with high performances (sub-picomolar detection limit) in measurement conditions approaching those occurring in vivo.
Authors : Giulia Casula, Piero Cosseddu, Annalisa Bonfiglio
Affiliations : Department of Electrical and Electronic Engineering University of Cagliari; Department of Electrical and Electronic Engineering University of Cagliari; Department of Electrical and Electronic Engineering University of Cagliari
Resume : Recently, flexible electronics has been attracting increasing attention thanks to its potential in different applications. Integration of multi-functional devices on a flexible substrate is the key point for the realization of actual products. So far, since fabrication process on flexible substrate is not trivial, device integration is still limited to few sensors and transistors. Moreover, for real practical applications, an essential function is a memory that retains information detected by a sensor. For example, a memory/sensor integration able to detect and memorize pressure/tactile information is an attractive flexible system for various application from electronics skin to smart packaging. In this work, a flexible organic memory/pressure sensor system is presented. In particular, non-volatile organic resistive memory devices with high performance will be considered: reproducible memory behavior with high on/off current ratio and remarkably long retention times will be shown. The actual possibility of employing these organic memories for storing information derived from external parameters detection by means of organic pressure-sensitive elements will be demonstrated. The novel memory/sensor system can be operated under ambient conditions with high retention time. Finally, the employment of the flexible system for the memorization of different shapes, including alphanumerical characters and geometrical figures, without loss of functionality, will be presented.
Authors : Maresova Eva1, 2, Tudor Alexandru3, Glennon Thomas3, Vrnata Martin2, Fitl Premysl2, Bulir Jiri1, Lancok Jan1, Vlcek Jan2, Tomecek David2, Pokorny Petr1, Novotny Michal1, Florea Larisa3, Coyle Shirley3, Diamond Dermot3
Affiliations : 1 Institute of Physics, Academy of Sciences of the Czech Republic; 2 University of Chemistry and Technology Prague, Dep. Physics and Measurements; 3 Insight Centre for Data Analytics, National Centre for Sensor Research, Dublin City University
Resume : In this work we focus on the preparation of a fabric-based chemical gas sensor with a sensitive layer based on Polymeric Ionic Liquids (PILs), namely Tetrabutyl phosphonium sulfopropylacrylate (P4444SPA) and butyl acrylate (50% molar) as a copolymer. The PILs are new class of polymeric materials, which possess the unique properties such as high conductivity, non-volatility, low toxicity and ability to form coatings which can actively respond to external stimuli. Therefore, they are promising material for chemical gas sensing. The basis of the proposed sensor is a nonwoven fabric (70% polyester, 30% polyamide) on whose surface were realized carbon interdigital electrodes (the space between the electrodes 0.5 mm) by screen printing technology (DEK 248 printer). There was observed that is necessary to choose the carbon ink of high viscosity for good adhesion to the textile substrate. To obtain a polymeric film, we applied a monomer mixture on the surface of the sensor and subsequently polymerized it directly on the fabric using the LMI-6000 Fiber-Lite white light source (200 kLux) for 20 min. The prepared fabric sensors were tested to selected analytes (NO2, CH3OH and 4-(Br)C6H4COCH3 ) at the concentration of 10 ppm. All measurements were carried out at room temperature. The response of the sensors were measured by the DC and AC measurement techniques. The DC-sensitivity of active layer was evaluated as the ratio SDC = Rair/Rgas. The highest DC-sensitivity of the sensor was observed in the atmosphere containing NO2 (SDC = 2,1), then in 4-(Br)C6H4COCH3 (SDC = 1,3) and CH3OH (SDC = 1,2). The surface morphology of the prepared samples were analyzed by scanning electron microscopy.
Authors : A. Ciavatti, L. Basiricò, A. Fraleoni-Morgera, P.J. Sellin, P. Cosseddu, A. Bonfiglio and B. Fraboni
Affiliations : A. Ciavatti; L. Basiricò; B. Fraboni - Department of Physics and Astronomy, University of Bologna A. Fraleoni-Morgera - Department of Engineering and Architecture, University of Trieste P.J. Sellin - Department of Physics, University of Surrey P. Cosseddu; A. Bonfiglio - Department of Electrical and Electronic Engineering, University of Cagliari
Resume : The light weight, simple processability, and mechanical flexibility of π-conjugated organic small molecules and polymers has recently led to remarkable research efforts towards the realization of new opto-electronic devices. Organic Semiconducting Single Crystals (OSSCs) exhibit the highest electrical performances among organic materials, thanks to their high chemical purity, high symmetry and molecular packing. The possibility of covering large areas with solution grown OSSCs by means of printing deposition techniques, has also been recently demonstrated, allowing their exploitation for a wide range of applications. Among the others, the development of flexible and large-area ionizing radiation detectors is extremely appealing since no low-cost, large-area, conformable and tissue equivalent detectors are currently available. In the last few years, we reported how solution-grown OSSCs based devices provide a direct (i.e. the X-ray photons are directly converted into an electrical signal), stable and linear electrical response to increasing X-rays dose rates, proving to be good ionizing radiation sensors, at room temperature. A dedicated study of the collecting electrodes geometry, crystal thickness and interaction volume allowed us to maximize the charge collection efficiency and sensitivity, thus assessing how even few micrometers thick OSSCs can perform at low operating voltages on PET flexible substrates. We also report about the ability of OSSCs to be employed as detectors of charged particles radiation in pulse mode operation, with very good detection efficiency, peak discrimination, and the extraction of the µτ value. The results pave the way to exploitation in the detection of neutrons, strongly interacting within hydrogen-rich organic molecules. [1 ]H. Minemawari et al., Nature, 475 (2011) 364-367.  B. Fraboni et al., Adv. Mater. 24 (2012) 2289-2293.  A. Ciavatti et al., Adv. Mater. 27 (2015) 7213-7220.  A. Ciavatti et al., Appl. Phys. Lett 108 (2016) 153301.
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Electronic Sensors : Annalisa Bonfiglio
Authors : Bastien Marchiori, Dr. Roger Delattre, Dr. Marc Ramuz
Affiliations : Mines St Etienne, Campus G. Charpak
Resume : Electronics of the future are expected to be foldable, twistable, and stretchable into curvilinear shapes to enable applications that would be impossible to achieve using today’s rigid, hard electronics. As a revolutionary technology, stretchable electronics has been changing our concept of electronics and brought us amazing features in numerous applications. Generally, such features are designed with soft materials as the interface between electronics and the human body or complex surfaces, e.g. epidermal electronic system. We present the fabrication of stretchable metallic connections patterned by laser ablation. Laser ablation is an ideal process for the production of fine features in materials deposited onto stretchable substrate. A short pulse laser is focused onto the surface to be ablated. The material heats up very rapidly and vaporizes to leave a small pit in the surface. Various sensors are targeted such as pressure, temperature, artificial eye and even biological sensor. For example, we present the integration of an organic electrochemical transistor (OECT) based on Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) onto a polydimethylsiloxane (PDMS) stretchable substrate. This stretchable sensor presents the advantages of superior mechanical matching between the active electronic device and the human body, easy implementation for in vivo recording. Moreover the PDMS substrate of the device, which is largely use for micro fluidics in biology, allows a higher level of integration of the OECT directly inside the fluidic channel for continuous recording.
Authors : Shantonu Biswas, Andreas Schöberl, Mahsa Mozafari, Jörg Pezoldt, Thomas Stauden, Heiko O. Jacobs*
Affiliations : [*] Corresponding-Author, Prof. H. O. Jacobs Fachgebiet Nanotechnologie Technische Universität Ilmenau Gustav-Kirchhoff-Strasse 1, D-98693 Ilmenau , Germany E-mail: firstname.lastname@example.org S. Biswas, A. Schöberl, M. Mozafari, Dr. J. Pezoldt, Dr. T. Stauden, Fachgebiet Nanotechnologie Technische Universität Ilmenau Gustav-Kirchhoff-Strasse 1, D-98693 Ilmenau , Germany
Resume : We report a method to produce single layer metamorphic stretchable printed circuit boards. Different from most reports the approach delays the use of the stretchable rubber support to the end of the processing sequence. Specifically, the entire circuit containing interconnects, unpackaged chips or chip-scale packaged surface mount devices (SMDs) are fabricated on a hard carrier. This facilitates high temperature processing, automated mounting, and precision alignment. Moreover, it enables “on-hard” carrier functionality tests, which are critical to determine correct functionality and a comparison of the performance metrics after the circuit is released. Application of the rubber support, release, and stretchability tests are last. As an application, the concept of metamorphic electronics is demonstrated. Our demonstrators are inflatable electronic structures and contain arrays with packaged SMDs and bare dies integrating light emitting diodes (LEDs) and transistors within a rubber matrix. The test structures morph from planar, to spherical, to cone like topologies.
Authors : Marco A. Squillaci1, Laura Ferlauto1,2, Yulian Zagranyarski3, Silvia Milita2, Klaus Müllen3, Paolo Samorì1
Affiliations : 1 ISIS & icFRC, University of Strasbourg and CNRS, 8 Allée Gaspard Monge, 67000 Strasbourg, France; 2 Istituto per la Microelettronica e Microsistemi (IMM)–CNR, via Gobetti 101, 40129 Bologna, Italy; 3 Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany;
Resume : Humidity sensors are of paramount importance in numerous science and technology fields thus are commonly used in industries, hospitals, environmental monitoring, etc. Hitherto, different transduction mechanisms have been explored in order to improve sensitivity, response speed, and recovery time by exploiting different properties as read-out, including optical and electrical characteristics (capacitance, resistance and gate effect in field-effect transistors as well as small mass changes). In this work we report on the use of smartly designed supramolecular fibers as electrical humidity sensors. This system is based on a light-triggered self-assembly of an amphiphilic electron donor–acceptor (D–A) dyad, made by a conjugated backbone, containing a tetrathiophene (4T) and a perylenediimide (PDI), connected by a conformationally rigid ethynylene spacer. These architectures, exposing ethylene glycol in their external shell, are employed as active components in resistive humidity sensors which combine a response rate as fast as 26 ms with an exponential growth of the current from 0 to, at least, 75% of relative humidity (RH). In this RH range, the current changes over up to 7 orders of magnitude, i.e. from a few pA to tens of mA, demonstrating an extremely high sensitivity to humidity variations.
Authors : Emil J. W. List-Kratochvil
Affiliations : Institut für Physik, Institut für Chemie und IRIS-Adlershof, Humboldt-Universität zu Berlin Brook-Taylor-Straße 6, 12489 Berlin, Germany
Resume : Comfortable, wearable sensors and computers will enhance every person’s awareness of his or her health condition, environment, chemical pollutants, potential hazards, and information of interest. In agriculture and in the food industry there is a need for a constant control of the condition and needs of plants, animals, and farm products. Yet many of these applications depend upon the development of novel, cheap devices and sensors that are easy to implement and to integrate. Organic semiconductors as well as several inorganic materials and hybrid material systems have proven to combine a number of intriguing optical and electronic properties with simple processing methods. As it will be reviewed in this contribution, these materials are believed to find their application in printed electronic devices allowing for the development of smart disposable devices in food-, health-, and environmental monitoring, diagnostics and control, possibly integrated into arrays of sensor elements for multi-parameter detection. In this contribution we review past and recent achievements in the field. Followed by a brief introduction, we will focus on two topics being on the agenda recently: a) the use of electrolyte-gated organic field-effect transistor (EGOFET) and b) ion-selective membrane based sensors for in-situ sensing of ions and biological substances. Here the realization of the ion-selective EGOFETs is discussed for reversible and selective ion and pH detection. As a second approach a reference electrode free all organic K+ sensitive ion sensing platform on a simple paper sheet is presented.
Authors : L. Basiricò1, A. Ciavatti1, T. Cramer1, P. Cosseddu2, A. Bonfiglio2, B. Fraboni1
Affiliations : 1 University of Bologna – Department of Physics and Astronomy, viale Berti Pichat 6/2, Bologna, Italy 2 University of Cagliari – Department of Electrical and Electronic Engineering, Piazza d’Armi, Cagliari, Italy
Resume : The research interest on alternative materials for innovative ionizing radiation detection is rapidly growing, in particular to envisage the need of large-area conformable sensor flat panels for applications that span from cultural heritage preservation to the security of public buildings. Organic materials have a strong potential for such an application, thanks to their mechanical flexibility and the possibility of deposition over large and bendable substrates by means of low-cost wet-technologies as printing techniques. Therefore, these feature permits to overcome the constraint of traditional inorganic materials, i. e. expensive or complex growth techniques and stiff mechanical properties. Recently, the employment of solution-grown organic materials as reliable direct X-ray detectors, operating at room temperature, have been demonstrated [1-3]. These studies opens the way to the development of a new class of fully flexible organic-based direct detectors with higher performances. In this work, we will report about results on organic thin-films based, fully bendable, devices as direct X-ray detectors, obtaining sensitivity values up to several hundreds of nC/Gy at ultra-low bias of 0.2 V. An analytical model accounting the signal amplitude and sensitivity values achieved and describing the mechanisms of collection and transport of the X-ray generated charges have been also developed. Finally, we assessed the possibility to use the detector under mechanical strain and gave the first demonstration of a 2×2 pixelated matrix organic detector.  B. Fraboni et al., Adv. Mater., 24, 17, 2289–2293, 2012.  B. Fraboni et al., Faraday Discuss., 174, 219, 2014.  L. Basiricò et al., IEEE Trans. Nucl. Sci., 62, 4, 1791–1797, 2015.
Authors : Eric Daniel Glowacki
Affiliations : Institute for Physical Chemistry, Johannes Kepler University, Linz, Austria
Resume : Here I review recent work on using natural-origin materials in semiconductor-based devices for interfacing with biology. Many natural materials offer both excellent semiconducting properties, and importantly, electronic as well as ionic conductivity. Biochemical systems are ionic, and not electronic, thus any attempts of active bioelectronics devices must involve ionic/electronic transducing elements. In particular, progress in the use of nanocrystalline and microcrystalline organic hydrogen-bonded pigments will be discussed. These materials have been ubiquitous throughout history and are widely produced today industrially as colorants in everyday products as various as cosmetics and printing inks, and have numerous properties that make them intrinsically biocompatible. The bioconjugation chemistry of these materials and subsequent deployment in electronic devices requiring reliable and specific bio-sensing will be covered.
Authors : Mirta Sibilia(1)(2), Nicola Demitri(2) and Alessandro Fraleoni Morgera(1)(2)
Affiliations : (1) Optoelectronics Laboratory - Dept. of Engineering and Architecture - University of Trieste - Via Valerio 6/A - 34127 - Trieste - Italy (2) Sincrotrone Trieste - Strada Statale 14 - km 163,5 - Basovizza - Trieste
Resume : Organic Semiconducting Single Crystals (OSSCs) are the ideal candidates in the field of organic electronics . Their application in the particular field of detection of ionizing radiation has been recently describedin a article where authors have shown – as a proof-of-principle - how OSSCs can be used as a new generation of direct electrical sensors . Many techniques are today available to prepare OSSCs suitable for devices fabrication. Among these, solution growth represents the best candidate, due to its: (i) simplicity, also applicable, in a properly developed form, to industrial purposes (e.g. inkjet printing or screen printing) ; (ii) high degree of crystal perfection, allowing good reproducibility of device performance ; (iii) ability of tuning crystal sizes ; (iv) low cost. The effect of systematic changes of some growth parameters (temperature, solution concentration, etc) has been studied. Some different compounds (i.e., 4hydroxycyanobenzene, 4HCB, and 2,4-dinitro-1-naphthol, MY) have been studied. To provide statistically reliable results, 5 batches per each growth condition have been prepared. Growth results have been analyzed in terms of: (i) number of single-crystals, (ii) number of poly-crystals, (iii) size of the crystals (iv) surface topography. Results have been rationalized based on thermodynamics, allowing to find the best growth conditions with respect to desired applications (like X-rays detection).
Authors : Cut Rullyani1, Ramesh Mohan2, Hong-Cheu Lin1 and Chih-Wei Chu2,3
Affiliations : 1 Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (ROC) 2 Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan (ROC) 3 College of Engineering, Chang Gung University, Tao-Yuan 333, Taiwan (ROC)
Resume : High demands of electronic appliances lead to increasing amounts of electronic wastes (E-wastes) that threaten the living organism by polluting the water, soil, and even the air. One potential way to reduce the accumulation of E-wastes is to use material that can be fully or partially naturally degraded or decomposed. Some organic materials have demonstrated their capabilities to accommodate this need. In this study, we introduce chitosan (i.e., a renewable polysaccharide) obtained from deacetylation of chitin and natural rubber (extracted from rubber tree) as substrate and dielectric materials for organic thin film transistors (OTFTs). By looking over the advantages of these biocompatible and biodegradable materials, we fabricated eco-friendly OTFT devices using organic semiconductor PTCDI-C8 and bilayer PVPy/NR and chitosan/NR as gate dielectric materials. The chitosan/NR device exhibited hysteresis free and low voltage performance, and it was found to give an electrical response in the presence of DNA with different concentrations. Moreover, chitosan possessed high transparency and good mechanical properties, and it could be easily casted to form a transparent flexible substrate. Finally, a disposable OTFT device fabricated with PVPy/NR as a dielectric material on chitosan substrate exhibited carrier mobility of 0.14 cm2V–1s–1, Vth of 0.8 V and 103 on/off ratio. The dielectric properties of bilayer films, along with OTFT device performance and sensing mechanism will be discussed.
Authors : Giulio Pipan1, Marco Bogar1, Andrea Ciavatti2, Laura Basiricò2, Tobias Cramer2, Beatrice Fraboni2, Alessandro Fraleoni-Morgera1,3,4
Affiliations : 1Dept. of Engineering and Architecture, University of Trieste, Italy 2Dept. of Physics and Astronomy, University of Bologna, Italy 3 CNR-NANO S3, Via Campi 213/A, Modena, Italy 4 Sincrotrone Trieste S.C.p.A., Italy
Resume : In the last years inkjet printing (IJp) has become a very important technology for creating flexible devices for electronics, due to its simplicity, low cost and high precision. One of the currently main prospected applications of IJp is the fabrication of organic electronics-based devices . TIPS-pentacene (TIPS) is one of the most promising materials for organic electronics, because of its excellent semiconducting behavior, which is comparable to that of hydrogenated amorphous silicon[2-3]. Here we report over IJp of solutions precursors to TIPS macroscopic single crystals (SCs), obtained from a single solvent ink. In particular, we will show that: - It is possible to print solutions able to originate SCs onto interdigitated electrodes, exploiting IJp fluorinated SAMs (f-SAMs) as an ink-containing corral; - Working in appropriate conditions it is possible to obtain oriented crystals; - The "printed" crystals have good electrical connection with the underlying electrodes; - The printed crystals can be used in X-rays direct detectors.  A. Teichler et al., J. Mater. Chem. C, 2013,1, 1910  Do Hwan Kim et al., Adv. Mater., 19, 2007, 678–682  S. K. Park et al., Appl. Phys. Lett., 2007, 91, 063514
Authors : Stefano Lai, Giulia Casula, Piero Cosseddu, Massimo Barbaro, Laura Basiricò, Andrea Ciavatti, Franck D'Annunzio, Christophe Loussert, Beatrice Fraboni, Annalisa Bonfiglio
Affiliations : S. Lai, G. Casula, P. Cosseddu, M. Barbaro, A. Bonfiglio - Department of Electrical and Electronic Engineering, University of Cagliari, Piazza d'Armi, 09123, Cagliari (ITALY); L. Basiricò, A. Ciavatti, B. Fraboni - Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy; F. D'Annunzio, C. Loussert - TAGSYS Europe, 785 Voie Antiope, Z.I. Athélia III, 13600 La Ciotat, France.
Resume : The detection of ionizing radiations over large areas is crucial for different applications including national security, biological and nuclear research. Inorganic materials are suitable for applications in biomedical fields were sensors dimensions are relatively small. When large areas are needed, the fabrication costs are generally prohibitive, due to the expensive growth methods for inorganic materials. For these applications, organic electronics is attracting a rising interest in the scientific community thanks to its peculiarities, such as low costs for large area fabrication over flexible, light-weighted substrates. In the last years, significant steps forward were made for organic sensors, but less has been done for the development of all organic electronics systems, and the readout of organic X Rays sensors is generally made by means of standard, inorganic electronic circuitries. Here, we report on an organic X Rays sensing system fabricated onto a flexible plastic substrate and working at low voltages, thus allowing battery operation. The core of the system is an organic, thin-film X Rays sensor; a transistor network is responsible for its polarization. The sensor response is employed to trigger the status of a latch composed by organic transistors and printed resistors, capable to perform long time memorization of the X Rays exposure. The status of the memory can be finally used for driving a transistor, whose current level allows an easy read out of the system.
Non organic sensors : Elvira Fortunato
Authors : Keon Jae Lee
Affiliations : Associate Professor, Department of Materials Science and Engineering, KAIST, 34141, South Korea
Resume : This seminar introduces three recent progresses that can extend the application of self-powered flexible inorganic electronics. The first part will introduce self-powered flexible piezoelectric energy harvesting technology. Energy harvesting technologies converting external sources (such as vibration and bio-mechanical energy) into electrical energy is recently a highly demanding issue. The high performance flexible thin film nanogenerator was fabricated by transferring the perovskite thin film from bulk substrates for self-powered biomedical devices such as pacemaker and brain stimulation. The second part will introduce flexible electronics including large scale integration (LSI) and high density memory. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication. To fabricate flexible large scale integration and fully functional memory, we integrated flexible single crystal silicon transistors with 0.18 CMOS process and memristor devices. The third part will discuss the flexible GaN/GaAs LED for implantable biomedical applications. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness. Our flexible GaN/GaAs thin film LED enable the dramatic extension of not only consumer electronic applications but also the biomedical devices such as biosensor or optogenetics. Finally, we will discuss laser material interaction for flexible and nanomaterial applications. Laser technology is extremely important for future flexible electronics since it can adopt high temperature process on plastics, which is essential for high performance electronics, due to ultra-short pulse duration. (e.g. LTPS process over 1000 °C) We will explore our new exciting results of this field from both material and device perspective.
Authors : Juergen Steimle
Affiliations : Department of Computer Science, Saarland University
Resume : Printable electronics allows for moving beyond mass-fabrication of sensors. We propose a new approach for personalized sensors: End-users design and print sensor surfaces of custom geometries. This enables highly personalized solutions, as required for the Internet-of-Things and for wearable computing. For instance, sensor surfaces can be tailored to fit within the physical context of use or can be tailored to fit an individual user’s anatomy. This presentation will focus on two key aspects that are indispensable for the end-user fabrication of printable electronics: 1) Easy-to-use and inexpensive printing processes, and 2) design principles that let end-users create personalized designs at a high level, abstracting from circuitry and the sensor’s inner workings. Based on these principles, we will demonstrate how end-users can realize flexible multi-touch sensor surfaces and touch-displays of custom geometry as well as personalized sensors that are integrated into 3D objects. Our contributions enable new applications for interactive paper, packaging, smart objects, and wearable computing.
Authors : Eun-Hyoung Cho, Jinyoung Hwang, Woong Ko, Jongmin Lee, Jeongyub Lee, Yongsung Kim, Chan Kwak and Chang Seung Lee
Affiliations : Platform technology lab, Samsung electronics (SAIT)
Resume : A partial etching mechanism is proposed to meet the requirement for low-visibility patterning of silver nanowire (AgNW)-based transparent conductive electrodes (TCEs) by reducing the difference in optical properties between conductive and nonconductive regions of the pattern. Using the finite difference time domain (FDTD) method, etched geometries that provide the smallest difference in transmittance after etching are theoretically determined. A sodium hypochlorite-based etchant capable that allows the etched geometry to be varied by controlling the pH is used to create a low-visibility pattern with a transmittance and haze difference of 0.07 and 0.04%, respectively. To the best of our knowledge, this is the first time that a partial etching mechanism such as this has been studied in relation to AgNW-based TCEs. Moreover, the TCE composite films with the high refractive index metal oxide nanosheets as the undercoating layer of AgNWs are suggested. The proposed two step partial etching process can result in the low diffuse reflection difference of 0.003% after patterning.
Authors : Marie Le Druillennec123, Vincent Mandrillon13, Rafael Estevez23, Guillaume Parry23, Bouchu David13, Christophe Poulain13
Affiliations : 1 CEA, LETI, MINATEC Campus, F-38054 Grenoble, France. 2 CNRS, SIMAP, F-38000 Grenoble, France 3 Université Grenoble Alpes, CNRS F-38000 Grenoble, France.
Resume : Inkjet or screen printing of silver nanoparticles on thin polymeric substrates is a versatile and promising technique for depositing highly electrically conductive interconnection lines for flexible electronics sensors. In order to ensure the reliability of such systems, a thorough knowledge of the mechanical stress induced failure mechanisms in the metallic layer is required. This work intends to investigate the cracking and delamination failure mechanisms. The studied samples consist of silver nanoparticles layers with a thickness between 500 nm and 9 µm deposited on 100 µm thick polyimide substrates (Kapton®) and followed by an annealing step at 150°C during 1 h. The mechanical induced failure experiments are performed on a tensile testing device. The samples are deformed up to 20 % strain. A combination of FIB slices and SEM images of tensile tested specimens allow the understanding of the cracking mechanism from initiation to propagation ending by the film delamination. Potential resulting buckling delamination is followed by in situ measurements. These identified mechanisms are modeled by finite element modeling with cohesive zone elements. Adhesion energy between the film and the substrate is then deduced from these simulations.
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Graphene and Carbon Nanotubes : Beatrice Fraboni
Authors : Satria Zulkarnaen Bisri
Affiliations : RIKEN Center for Emergent Matter Science, Japan
Resume : Semiconducting single-walled carbon nanotubes (sSWNTs) remain at the forefront of the most prospective materials for electronic device applications "beyond Moore`s law", despite the emergence of many other competing materials, including graphene, and the other graphene-like semiconductors. Their 1D nature appears as the most suitable structure to support the current advancement goals of post-silicon-electronics, i.e. nm dimensions (ultrathin body) allowing high device density and gating them all-around. One greatest challenge for the use of sSWNTs in flexible electronic devices is on how to completely separate and purify them from the metallic species that come together during their synthesis. In this talk, the progress on the separation and purification of sSWNTs using conjugated polymer wrapping will be extensively explained. Polymer selections and optimization of process parameters to obtain pure sSWNTs with controlled diameters will be briefly introduced. The demonstration of high performance FETs of both networks and individual of the polymer-wrapped sSWNTs will be shown, in which combination of both high on/off ratio and high mobility in ambipolar devices are achieved. These demonstrations, together with their solution-processability, have strong implication for their utilization for flexible electronics (e.g. sensors, photovoltaics and thermoelectrics). In the end, the peculiar charge carrier transport mechanism in polymer-wrapped sSWNTs networks will be discussed.
Authors : Joohee Kim, Jang-Ung Park*
Affiliations : School of Materials Science and Engineering, Wearable Electronics Research Group, Center for Smart Sensor Systems, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
Resume : Healthcare applications of wearable and smart sensors which can monitor human health conditions noninvasively with function of wireless transmission have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, the transparent and stretchable sensors integrated on the biomaterials are not yet been realized. In this talk, we presented a multifunctional sensor for human disease diagnosis based on a RLC circuit, where R (resistance) responds to molecular binding of biomarkers in the body fluid while L (inductive) and C (capacitance) change in accordance with structural changes of capacitance materials induced by varying pressure. This device based on hybrid nanostructures using two-dimensional graphene and one-dimensional metal nanowire exhibited high transparency, superb stretchability, and hence enabled the device to be fittable on biomaterials with wireless sensing capability. Furthermore, in-vivo and ex-vivo tests demonstrated its reliable operation. The advance of these electronics using hybrid structures provides a route towards future electronics.
Authors : Jihun Park, Joohee Kim, Kukjoo Kim, Jang-Ung Park*
Affiliations : School of Materials Science and Engineering, Wearable Electronics Research Group, Center for Smart Sensor Systems, Ulsan National Institute of Science and Technology (UNIST) Ulsan, 44919, Republic of Korea
Resume : Recent advance in wearable electronics has contributed to the rapidly increasing interest for the Internet of Things (IoTs) that can consistently monitor signals. For realization of IoTs, the devices should possess sufficient stretchability to attach conformably to any nonplanar objects. In addition, optical transparency is also required to improve the natural look of the devices. In this regard, the conventional transparent conductor must be substituted by stretchable transparent electrodes for wearable devices. For this purpose, we chose metal nanowires (mNW)-graphene hybrid nanostructures due to their superb electrical conductivity (<30 Ω/sq), transparency (>90%), and stretchability. As another key function of IoTs, the wearable devices are required to accompany wireless communication systems for consistent monitoring. For this function, sensors should always transmit acquired data to users for interaction. Here, we report the realization of stretchable graphene sensors based on the silver nanowire-graphene hybrid nanostructures. The device shows high stretchability and transparency while maintaining their sensing capability for the simulant of nerve agent (dimethyl methylphosphonate). The fabricated sensors show outstanding sensing parameters (e.g., sensitivity and recovery, etc.). Furthermore, in order to realize IoTs which can monitor environments continuously, we integrated the sensors with wireless communication systems (Bluetooth and inductive antennas). The integrated sensors also retain high sensing performances on the nonplanar objects (e.g., leaves of live plant). We believe that the realization of wearable and wireless gas sensors suggests a promising strategy toward IoT devices.
Authors : Jing Ren, Wenjun Zhang, Yubo Wang, Yaxiong Wang, Jun Zhou, Liming Dai, Xing Lu, Ming Xu
Affiliations : State Key Laboratory of Materials Processing and Die & Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Resume : Strain sensors for human health monitoring are of paramount importance in wearable medical diagnostics and personal health monitoring. Despite extensive studies, strain sensors with both high durability and stretchability are still desired, particularly with the stability for different environmental conditions. Here we report a series of strain sensors possessing the graphene network with a high density of intermittent physical interconnections, which produces the relative resistance change by varying the overlap area between the neighboring graphene sheets under stretching and releasing, analogous to the slide rheostat working in electronics. Our in-situ transmission electron microscope observation reveals the full recoverability of the structure from large deformation upon unloading for ensuring the exceptional cycability of our material on monitoring full-range body movements, which has not been achieved by any conventional graphene-based strain sensors before. The stable response is also demonstrated over wide temperature range and frequency range, since the peculiar dynamic structure can be maintained through the self-adjustment to the thermal expansion of the bulk material. Based on the working mechanism of graphene “slide rheostat”, the sensing properties of the strain sensor are tailored by tuning the graphene network structure with different mass densities using different concentration of graphene oxide dispersion, while the stretchability and sensitivity can be separately optimized for different application requirements.
Novel Applications : Annalisa Bonfiglio
Authors : Robert Nawrocki, Sunghoon Lee, Naoji Matsuhisa, Tomoyuki Yokota, and Takao Someya
Affiliations : 1Department of Electrical Engineering and Information Systems, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan 2Advanced Leading Graduate Course for Photon Science, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Resume : 1. INTRODUCTION The goal of creating an artificial skin capable of monitoring medical conditions, for instance with electrodes placed directly on patient’s skin or on the heart, requires ultra-thin, flexible, stretchable, conformable and bio-compatible electronics [1, 2]. Furthermore, the biological signals are relatively weak and often need further electrical amplification . The use of hard, thick and inflexible inorganic electronics presents a challenge for soft, oddly shaped, and very porous human bodies and organs, as these electronics have to be embedded in soft organic materials before implantation . Organic electronics promises to fulfil all of the aforementioned constraints without the need of additional encapsulation, resulting in much thinner, flexible, and conformal devices . The bending thickness, and subsequently the conformity, of a thin film is proportional to its thickness cubed . Decreasing the total thickness of the electronics therefore significantly reduces the bending stiffness making the devices much more conformal to the organ’s surface roughness, allowing for more accurate, as well as more comfortable, monitoring of biological signals. Amplifying a signal closer to the source typically leads to a higher signal-to-noise ratio, requiring ultra-thin-film amplifiers, to be deployed, for instance, on the skin or on the brain . We will review past achievements of our group, including the fabrication of ~2 µm thin electronics, such as polymer transistors, polymer light emitting diodes, organic solar cells, and magneto-electronics. We will also present more recent successes, including flexible temperature and pressure sensors, as well as multi-element integration of a photonic e-skin and thin and flexible organic amplifiers. We will discuss the fabrication of the world’s thinnest, sub-300-nm e-skin, fit with transistors, tactile sensors, as well as pseudo CMOS and CMOS amplifiers. Finally, stretchable conductors, integrated with a flexible EMG matrix, will be presented. 2. ACHIEVEMENTS 2.1 Past achievements We have, in the past fabricated an array of thin and flexible organic field effect transistors (OFETs), with DNTT as the active material . Fabricated directly on 1 µm PEN substrate, these electronic circuits were ultra-light, with a bending radius of ~5 µm, and capable of flexing on 230% pre-stretched elastomer. Active matrix array of OFETs, matched with tactile, bolometer, and temperature sensors, was demonstrated. Organic Photovoltaic (OPV) cells, fabricated on 1.4-μm-thick PET, were shown . With PET/PEDOT:PSS/P3HT:PCBM/Ca/Ag architecture, these devices were capable of 80% compression rate and a bending radius of less than 35 µm, with FF of 71%, JSC of 12 mA/cm2, and power conversion of 4.2%. Red and orange polymer light emitting diodes (PLEDs), fabricated on 1.4-μm-thick PET, were revealed . With device architecture of PET/PEDOT:PSS/AnE-PVstat/LiF/Al, devices showed luminance >100 cd/m2, bending radius of ~10 μm, and stretch-compatibility of 100% tensile strain. Flexible (bending radii <3 μm) and lightweight magneto-resistive sensors were fabricated with a total thickness of ~2 μm . Based on multilayers of Co/Cu or Py/Cu, they were shown capable of reaching strains of >270% and enduring over 1,000 cycles without fatigue. 2.2 Temperature and pressure sensor The ability to monitor parameters, such as temperature and pressure, is essential in the healthcare industry. Physically flexible and conformal sensors allow for more accurate monitoring, which is also less intrusive to the patient. To this end, more recently we have fabricated flexible and printable temperature sensor . Based on semi-crystalline acrylate polymers and graphite, this ultra-sensitive sensor (0.02 °C) has a tunable sensing range of 25 °C to 50 °C, fast response time of <100 ms, low bending radius of <700 μm, and a high repeatability of 1800 times. Its utility was demonstrated with in vivo measurement of temperatures changes of a rat lung during breathing. We showed a high transparency and high pressure sensitive sensor that measures only the normal pressure, even under extreme bending conditions . Based on composite nanofibers of carbon nanotubes and graphene, sensor with the bending radii of ~80 μm, and a response time of 20 ms, was achieved. To test its utility, we showed an integrated sensor matrix that was only 2 μm thick. 2.4 Photonic skin and organic amplifiers The ability to measure and display is often taken for granted in standard, thick and bulky electronics. However, while extremely useful, such functionalities are immensely difficult to achieve on the same ultrathin substrate. Ultraflexible organic photonic optoelectronic or OE-skin was fabricated . At about 3 μm thin, with bending radii of 100 μm and tensile strain up to 200%, the OE-skin was fit with tri-color (red, green, and blue) PLEDs and OPVs, and subsequently laminated on human skin. The OE-skin was laminated on a human finger, and used to make a reflective pulse oximeter, to measure and display blood oxygen level. Measuring relatively weak biological signals often requires electrical amplification. We showed e-skin based on highly conductive gel composite comprising of multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel (admittance of 100 mS/cm2), and ultrathin and mechanically flexible organic active matrix amplifier on a 1.2- μm-thick PEN film, capable of amplifying (up to 46 dB) weak bio-signals . Implantation onto a rat’s heart, for 4 weeks, resulted in low foreign-body reaction (as compared to metal electrodes). 2.6 Sub-300-nm e-skin The bending stiffness, and conformability of a film is proportional to its thickness. To achieve electronics capable of conforming to surface of arbitrary roughness, we have created a world’s thinnest, sub-300-nm thin, including the substrate and encapsulation layers, e-skin. Fit with tactile sensors and organic transistors (parylene/Au/parylene/DNTT/Au/parylene), this e-skin is also the world’s lightest, weighting less than 0.7 g/m2 . Fabricated on a glass substrate, the film was manually delaminated followed by immersion in water. The e-skin can be repeatedly bent to radii less than 2 µm and accommodate repeated stretching (100 times) on a 60% pre-stretched elastomer, while retaining its good electrical characteristics (VDS = -5 V; µ = 0.35 cm2/Vs; ON/OFF ratio ~105; VT = -1.72 V). Biocompatibility of this e-skin was demonstrated by deposition on a human skin without any noticeable irritability. To fully realize the potentials of this ultra-thin and ultra-light e-skin in healthcare and biomedical fields, we have fabricated sub-300-nm thin pseudo-CMOS and CMOS amplifiers. With an operating voltage of 5 volts, the pseudo-CMOS amplifiers showed a maximum gain of up to 37 dB. CMOS amplifiers (PDI-8CN2 as the active n-type material) were fabricated into a multistage arrangement (up to five cascaded stages), with a maximum gain calculated of up to 79 dB. Both, the pseudo-CMOS and CMOS amplifiers were subjected to physical deformation (100 times) on a 50% pre-stretched elastomer, and showed to retain their high electrical performance. 2.7 Stretchable conductors With wearable electronics in mind, we have developed a printable elastic conductor with a high initial conductivity of 738 S/cm and a record high conductivity of 182 S/cm when stretched to 215% strain . This elastic conductor ink was formulated from Ag flakes, a fluorine rubber and a fluorine surfactant, with the surfactant being a key component in the high conductivity and stretchability. Its utility was demonstrated with fabrication of a stretchable organic transistor active matrix on a rubbery stretchability-gradient substrate, with unimpaired functionality when stretched to 110%, and a wearable EMG sensor printed onto a textile garment. REFERENCES 1. Mühl, S. and B. Beyer, Bio-Organic Electronics—Overview and Prospects for the Future. Electronics, 2014. 3(3): p. 444. 2. Gibney, E., The Body Electric; The inside story on wearable electronics. Nature, 2015. 528: p. 26-28. 3. Viventi, J., et al., Flexible, foldable, actively multiplexed, high-density electrode array for mapping brain activity in vivo. Nat Neurosci, 2011. 14(12): p. 1599-1605. 4. Hwang, G.-T., et al., In Vivo Silicon-Based Flexible Radio Frequency Integrated Circuits Monolithically Encapsulated with Biocompatible Liquid Crystal Polymers. ACS Nano, 2013. 7(5): p. 4545-4553. 5. Irimia-Vladu, M., et al., Green and biodegradable electronics. Materials Today, 2012. 15(7–8): p. 340-346. 6. Kim, D.-H., et al., Dissolvable films of silk fibroin for ultrathin conformal bio-integrated electronics. Nat Mater, 2010. 9(6): p. 511-517. 7. Kaltenbrunner, M., et al., An ultra-lightweight design for imperceptible plastic electronics. Nature, 2013. 499(7459): p. 458-463. 8. Kaltenbrunner, M., et al., Ultrathin and lightweight organic solar cells with high flexibility. Nat Commun, 2012. 3: p. 770. 9. White, M.S., et al., Ultrathin, highly flexible and stretchable PLEDs. Nat Photon, 2013. 7(10): p. 811-816. 10. Melzer, M., et al., Imperceptible magnetoelectronics. Nat Commun, 2015. 6. 11. Yokota, T., et al., Ultraflexible, large-area, physiological temperature sensors for multipoint measurements. Proceedings of the National Academy of Sciences, 2015. 112(47): p. 14533-14538. 12. Lee, S., et al., A transparent bending-insensitive pressure sensor. Nat Nano, 2016. 11(5): p. 472-478. 13. Yokota, T., et al., Ultraflexible organic photonic skin. Science Advances, 2016. 2(4). 14. Sekitani, T., et al., Ultraflexible organic amplifier with biocompatible gel electrodes. Nat Commun, 2016. 7. 15. Nawrocki, R.A., et al., 300-nm Imperceptible, Ultraflexible, and Biocompatible e-Skin Fit with Tactile Sensors and Organic Transistors. Advanced Electronic Materials, 2016. 2(4). 16. Matsuhisa, N., et al., Printable elastic conductors with a high conductivity for electronic textile applications. Nat Commun, 2015. 6.
Authors : Martin Kaltenbrunner
Affiliations : Department of Soft Matter Physics, Johannes Kepler University, Linz, Austria
Resume : Electronics of tomorrow will be imperceptible and will form a seamless link between soft, living beings and the digital world. This new form of ultra-conformable electronics places severe physical requirements on the active components that constitute modern foil-like electronic systems. Weight and flexibility become key figures of merit for large area electronics such as robotic skin, as they critically influence the mechanical response and perception of the artificial sensory system. With less than 2 μm total thickness, imperceptible electronic foils are light (≈3-5 g m-2) and unmatched in flexibility, they are operable with radii of curvature below 5 µm, yet highly durable and withstand severe crumpling without any performance degradation. These are prerequisites for intimate contact with soft, biological tissue or organs and complex, arbitrarily shaped 3D free forms that enable applications spanning medical, safety, security, infrastructure, and communication industries. This talk introduces a technology platform for the development of large-area, ultrathin and lightweight electronic and photonic devices, including solar cells[1,2], light emitting diodes and photodetectors active-matrix touch panels, implantable organic electronics[6,7], imperceptible electronic wraps and “sixth-sense” magnetoception in electronic skins. Solar cells, less than 2 µm thick, endure extreme mechanical deformation and have an unprecedented power output per weight of 23 W/g. Highly flexible, stretchable organic light emitting diodes are combined with photodetectors for on-skin photonics and pulse oximetry, providing electrical functionality in yet unexplored ways. Tactile sensor arrays based on active-matrix organic thin film transistors can be operated at elevated temperatures and in aqueous environments as an imperceptible sensing system that ensures the smallest possible discomfort for patients requiring medical care and monitoring. Combined with organic amplifiers and biocompatible hydrogels, we demonstrate in vivo recording of vital signals. E-skins with GMR-based magnetic field sensors equip the wearer with an unfamiliar sense that enables perceiving of and navigating in magnetic fields. These large area sensor networks build the framework for electronic foils and artificial sensor skins that are not only highly flexible but become highly stretchable and deployable when combined with engineered soft substrates such as elastomers, shape memory polymers or tissue-like hydrogels. References  M. Kaltenbrunner et al, Nature Communications 3:770, 1-7 (2012)  M. Kaltenbrunner et al, Nature Materials 14, 1032-1039 (2015)  M. White et al, Nature Photonics 7, 811–816 (2013)  T. Yokota et al, Science Advances 2:e1501856 (2016)  M. Kaltenbrunner et al, Nature 499, 458-464 (2013)  T. Sekitani et al, Nature Communications 7:11425 (2016)  J. Reeder et al, Advanced Materials 26, 4967-4973 (2014)  M. Drack et al, Advanced Materials 27, 34-40 (2015)  M. Melzer et al, Nature Communications 6, 1-8 (2015)
Authors : Jeonghyun Kim, Philipp Gutruf*, Anthony Banks, Seung Yun Heo, Zhaoqian Xie, Yonggang Huang and John A. Rogers *presenting Author
Affiliations : Jeonghyun Kim; Philipp Gutruf; Anthony Banks; Seung Yun Heo; John A. Rogers Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory University of Illinois at Urbana–Champaign Urbana, IL 61801, USA Zhaoqian Xie; Yonggang Huang Department of Mechanical Engineering Civil and Environmental Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University Evanston, IL 60208, USA
Resume : The development of mechanically deformable and thin electronics offers a platform for a variety of exciting new applications through conformal contact to the skin. However a major challenge in achieving a wireless system, is the delivery of electrical power and communication. Near field communication (NFC) is a suitable technology offering wireless power transfer as well as communication capabilities on widely available platforms such as smartphones. Here we present strategies of integrating such an NFC system into an epidermal and fingernail platform allowing for a battery free operation. Mechanical design considerations are made to match the mechanical properties of the electrical system to the human epidermis resulting in conformal contact. Furthermore we demonstrate a miniaturization of such a system to allow for the integration onto a fingernail. Experimental and Finite Element Analysis characterization of the devices is employed to demonstrate electrical and mechanical robustness resulting in uninterrupted operation during daily activities. Additionally we demonstrate the capability of supporting sensor systems which allows for the acquisition of vital signs data.  J. Kim, A. Banks, H. Cheng, Z. Xie, S. Xu, K. I. Jang, J. W. Lee, Z. Liu, P. Gutruf, X. Huang, Small 2015, 11, 906-12  J. Kim, A. Banks, Z. Xie, S. Y. Heo, P. Gutruf, J. W. Lee, S. Xu, K. I. Jang, F. Liu, G. Brown, Advanced Functional Materials 2015, 25, 4761-7
Authors : Daniel J. Joe, Erik O. Gabrielsson, Jae Hyun Han, Daniel T. Simon, Magnus Berggren, and Keon Jae Lee
Affiliations : Daniel J. Joe; Jae Hyun Han; and Keon Jae Lee; Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 34141, Daejeon, South Korea, Erik O. Gabrielsson; Daniel T. Simon; and Magnus Berggren; Department of Science and Technology, Linköping University, SE-601 74, Norrköping, Sweden
Resume : Electrochemical devices based on conjugated polymers such as biosensors and ion transistors have received significant attention in bioelectronic applications. In particular, conjugated polymers have been known to be suitable for integration with biological systems since they can be soft, flexible, biocompatible, and both electronically and ionically conductive. In order for successful demonstration of the integrated bioelectronic systems, in vivo implementation of a battery is essential to supply electric power necessary for each iontronic component. Recently, flexible energy harvesters have emerged as a promising alternative to the batteries as they generate sufficient electrical energy to operate such devices. In this work, we demonstrate a high-performance flexible piezoelectric energy harvester consisting of a large-area PZT thin film on a plastic substrate to operate self-powered iontronic devices. A 2 μm thick crystalline PZT film on a rigid sapphire substrate, which was annealed at 650 °C in air for 45 minutes, is successfully transferred onto a flexible polyethylene terephthalate (PET) substrate via laser lift-off (LLO) without any structural damages or material degradation. The flexible PZT energy harvesting devices typically generate an open circuit voltage of ~200 V and a short circuit current of ~8 μA transduced from small mechanical deformation. The electrical output produced from slight bending and unbending motions by human hands charge capacitors and turn on more than 200 commercial blue LEDs. Finally, a self-powered hybrid ionic circuit is implemented with PZT energy harvesters, full-wave bridge rectifiers, energy storage elements, and iontronic devices, such as organic electronic ion pumps (OEIP) and ion bipolar junction transistors (IBJT). During the rectification followed by the energy storage, AC output of the harvester is converted into the DC to charge a 100 μF capacitor up to 5.3 V within ~25 minutes. The stored energy provides electrical current of ~150 nA to the OEIP lasted for ~20 minutes. The self-powered OEIP made of a biocompatible material known as PEDOT:PSS is utilized to precisely deliver acetylcholine (Ach), a neurotransmitter that regulates neuronal cell signaling and controls amyloid reactions, with a rate of ~10 pmol/μC. In addition to the passive components as OEIPs, the stored energy also successfully operates nonlinear components as IBJTs to examine addressability of the substance delivery. With a square wave emitter-base voltage of +/- 1 V, a small ionic base control signal actively modulates a relatively much larger ionic collector output signal.
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