Organic bioelectronics

Resume : The introduction in the early 70s of the Ion Sensitive Field Effect Transistor (ISFET) represented a real turning point in several fields since it allowed the realization of compact, label-free, and versatile sensors and biosensors. Despite their great potentiality, ISFET-like devices generally suffer from an intrinsic limitation in sensitivity, the so-called Nernst limit. Moreover, the high costs, the restricted range of employable materials associated to the silicon technology, and the need for a reference electrode, have reduced the applicability of such devices in the bio-sensing field, in particular in in vivo applications. We have developed a reference-less sensor based on an organic semiconductor device, called Organic Charge-Modulated Field-Effect Transistor (OCMFET), that besides being low cost, flexible, and transparent, shows a super-nernstian sensitivity to pH variations with no need of any chemical modification of the sensing area. Moreover, thanks to its peculiar transduction principle and structure, the device sensitivity can be easily tuned by acting on geometry-related parameters of the device itself. The proposed approach has been applied for monitoring cell metabolic activity, demonstrated with a preliminary validation. In addition this device can be used for monitoring electrical activity of excitable cells, thus giving rise to a new family of highly sensitive, reference-less, and low-cost devices for a wide range of bio-sensing applications.

Resume : A major goal of electrode fabrication for application in microelectrode array (MEA) technology for extracellular cell signal recordings is to achieve low impedance because it results in a higher signal-to-noise ratio (SNR). Therefore, research has been focused on increasing the effective surface area by modifying the electrode with porous conducting materials, nanostructures, carbon nanotubes, and conducting polymers [1,2]. This contribution shows that the detection limit of extracellular electrodes can be brought down to few nanovolts. Bioelectrical signals with amplitudes of 150 nanovolts in a noise level of 20 nanovolts (peak-to-peak) with a SNR >7 were recorded using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) based electrodes. The strategy behind this ultra-high sensitivity is to use high capacitive electrodes (capacitance > 50 μF/cm2 at 100 Hz) and observation windows below a frequency of 10 Hz. Our methodology is not suited to measure fast action potentials produced by neurons, but allows the observation of weak and low frequency biological signals that have remain inaccessible using extracellular electrodes. The electrodes and the methodology are demonstrated by recording ultra-weak signals produced by primary cultures of astrocytes and glioma cell cultures. Our electrical measurements are confirmed by optical fluorescence recordings carried out in parallel and in line with previous reports in literature confirming that these cells produce signals in the scale of a several seconds up to minutes. [1] P. Leleux et al. Adv. Healthc. Mater., vol. 3, no. 4, pp. 490–493, 2014. [2] M. E. Spira and A. Hai, Nat. Nanotechnol., vol. 8, no. 2, pp. 83–94, 2013.

Resume : Reliable device operation in aqueous media is a critical requirement for bioelectronics. In this work, we evaluate the behavior of various poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based devices under water and suggest a effective strategy to improve both their electrical performance and operational stability via solvent-assisted crystallization. Crystallized PEDOT:PSS (c-PEDOT:PSS) exhibit a compact PSS-deficient nanoscale reticulum with enhanced swelling resistance index and volumetric capacitance by factors of 4.8 and 17, respectively. Furthermore, electrochemical transistors based on c-PEDOT:PSS show transconductance over 20 mS, contact resistance under 1 Ohm/cm, switching reproducibility over 2000 cycles, stress endurance over 20 days, and excellent compatibility with autoclave sterilization. We expect that c-PEDOT:PSS-based electrochemical transistors becomes a promising platform for a variety of advanced organic bioelectronics.

Resume : In recent years, in vitro models are increasingly requested for toxicology and drug development. The main aspect under study is the monitoring of cell stress and death induced by drug treatments. The standard methods for investigating cell viability provide high throughput results together with reliability and sensitivity, nevertheless these techniques are mostly based on an optical monitoring, using cromo/fluorophores and complex laboratory protocols. This has generated an increasing demand for easier, faster and portable tools for cell viability screening. Thus, the ability of monitoring simultaneously the cells both optically and electrically in vitro is a very attractive proposition. We realized organic electrochemical transistors (OECTs) based on conductive polymer PEDOT:PSS, with low cost fabrication techniques. The biocompatibility of this polymer allows the growth of cells directly on the electrode and its high transparency permits to correlate the electrical measurement with the high resolution imaging commonly used for life-science research. The reliability of OECTs to detect the cell viability was demonstrated by monitoring the effect of toxic agents on different cells culture (i.e. HeLa, NIH 3T3). We have been able to evaluate in real time tissue cells formation and its disruption induced by toxic agent (i.e. trypsin), enhancing the information normally obtained with standards optical techniques.

Resume : The development of innovative bioelectronic devices for monitoring nerve cells activity with improved biocompatibility, sensitivity and spatiotemporal resolution is a stringent condition to understand brain physiology and pathophysiology. We have already demonstrated that primary neurons can adhere, grow and differentiate on a suitably engineered perylene-based thin-film transistor platform, while maintaining their firing properties even after a prolonged time of cell-culturing [1]. Moreover, we implemented the platform called organic cell stimulating and sensing transistor device (O-CST) for stimulating the neuronal cells and recording the bioelectrical activity [2]. Here, our recent activity concerning the validation of O-CST for the study and manipulation of ion channels and calcium signaling in non excitable (glial) cells and on the study of sensing and transduction mechanisms of O-CST will be presented. O-CST is biocompatible with astrocytes and its operation lead to an exclusive increase in the astroglial inward whole-cell conductance that we could attribute to specific ion channel. We also found that O-CST stimulation evokes an intracellular calcium increase, which can be monitored by calcium imaging due to the O-CST's transparency. Notably, by a combination of patch-clamp, calcium imaging and computational analyses, we show that the evoked current and calcium response are dependent on the O-CST device architecture. Furthermore, by performing Electrical Impedance Spectroscopy (EIS), we propose the working principles of the sensing mechanism of the O-CST architecture by introducing a suitable equivalent circuit. We succeeded in validating a macroscopic model by achieving surface potential maps of the organic layer surface after the device biasing in wet conditions [3]. Collectively, our results confirm the potential of O-CST for selective manipulation of bioelectrical activity of neural cells and describe a model that is straightforward to discriminate the different processes occurring at the interphase between the electrolyte and the organic layer which rule the ions-electrical transduction mechanism in the device. [1] Toffanin S., Benfenati V., Muccini M. et al., J Mater Chem, 2013, 1, 3850-3859. [2] Benfenati V., Toffanin S., Muccini M. et al., Nature Materials, 2013, 12, 672-680. [3] Lago N., Muccini M., Toffanin S., et al., Organic Electronics, 2016, 35, 176–185.

Resume : Poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) is a conducting polymer that is widely used in organic bioelectronics due to its outstanding electrochemical properties and ease of processing. Most of the devices that employ this material use only flat PEDOT:PSS films. A study on the patterned structures of this material and its effect on the electrochemical properties and device performance is of interest as it can reveal mechanisms that lead to enhanced parformace. In this work we present a study of the electrochemical impedance of nano-patterned PEDOT:PSS films and explain changes based on an equivalent circuit model. These films surfaces were also used as scaffolds for cell growth. We discuss the correlation of cell morphology with the underlying structure.

Resume : Organic field-effect transistors (OFETs), and in particular electrolyte-gated OFETs (EGOFETs), are emerging as an important class of chemo- and bioensors to meet the main requirements of healthcare diagnostics: portability, low cost, miniaturization. These devices provide a real-time, label-free response and the ultra-low sensitivity arising from the capacitive coupling between the electrolyte solution and the channel. Many OFET biosensors exploits immunorecognition events, and their sensing unit features immobilized antibodies (Abs) on the relevant EGOFET interfaces. Despite very promising achievements, there is still room for significant improvements, if one may overcome the caveats related to the use of Abs. Such limitations include multiple functionalization steps, large dimensions, high molecular weight, poor sequence control, relative instability, especially when adsorbed on a substrate. Protein aptamers are emerging as one of the most solid alternatives to Abs. We demonstrate EGOFET-based aptasensors with Affimer-functionalized gate for the ultra-sensitive detection of inflammatory biomarkers with limit of detection below 1 pM even in biological fluids. We compare the performances of Abs- and aptamer-based biosensors and we discuss what device parameters (changes of current, charge mobility, Vth) and what models may be used to investigate the thermodynamics of the biorecognition. We gratefully acknowledge MIUR Bilateral Project IT/SE “Poincaré” for support.

Resume : There has been interest recently in the use of conducting polymer electrodes as extracellular electrodes to record signals of cells, which provide better recordings. A theoretical framework is needed to interpret the coupling of bioelectrical signals and polymer/electrolyte interface. This study uses COMSOL Multiphysics® to simulate the electrical coupling and to gain insight into the parameters controlling the cell/polymer interface. Electrodes were prepared using PEDOT:PSS deposited in a variety of soft substrates including nano-cellulose and PET. Polymer deposition was performed using inkjet printing and spin coating methods. The substrate and fabrication affect surface roughness but also polymer surface physico-chemical properties. The electrodes were evaluated using autonomous cardiac contractile cells, small voltage pulses and small-signal impedance measurements, to extract the individual equivalent circuit components of the electrical double-layer. The parameters are used in the models of the electrical coupling, with the interfacial (or spreading) resistance being an important parameter that takes into account the signal loss from the cell to the electrode. Variations in this resistance were quantified and discussed, providing important guidelines for the optimization of polymer electrodes for extracellular recordings.

Resume : Recent interest in making the electronic-biological interface as seamless as possible has prompted the exploration of electronic materials that are soft, stretchable and mechanically comfortable, which are important properties for interacting with biological system in both wearable and implantable devices [1,2]. Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), deposited from a commercially available dispersion, has been used as a model system for these studies. Different cross-linking schemes have been used to stabilize films of this material against delamination and re-dispersion, but the cost to pay is a decrease in the electrical conductivity and/or additional heat treatment. Here we introduce divinylsulfone (DVS) as a new cross-linker for PEDOT:PSS. Thanks to the higher reactiveness of the vinyl groups of DVS, the cross-linking can be per-formed at room temperature. In addition, DVS does not reduce electronic conductivity. Cell culture studies show that PEDOT:PSS:DVS films are cytocompatible and support neuroregeneration. These results pave the way for the utilization of DVS as an effective cross-linker for PEDOT:PSS. [1] Rivnay, J.; Owens, R. M.; Malliaras, G. G. The Rise of Organic Bioelectronics. Chem. Mater. 2014, 26 (1), 679–685. [2] Rivnay, J.; Leleux, P.; Ferro, M.; Sessolo, M.; Wil-liamson, A.; Koutsouras, D. A.; Khodagholy, D.; Ramuz, M.; Strakosas, X.; Owens, R. M.; Benar, C.; Badier, J.-M.; Ber-nard, C.; Malliaras, G. G. High-Performance Transistors for Bioelectronics through Tuning of Channel Thickness. Sci. Adv. 2015, 1 (4).

Resume : Rapid and accurate detection of pathogens is a major challenge in many areas including health, food or military applications. In the past decades the interest of developing biochips, notably glycan biochips for this specific purpose is continuously increasing. Different methods of detection of bacteria were developed with good sensitivities such as indirect (fluorescence) or direct (Electrochemical Impedance Spectroscopy or Surface Plasmon Resonance) methods but as far none of them are able to verify the nature of pathogens interacting with the probes or to identify their strains. We aim to develop a new architecture of biochip for the direct and multiplex analysis of the spectroscopic fingerprints of pathogens by using Surface enhanced Raman spectroscopy (SERS) imaging. In this poster, we will describe our biochip design which is constituted of plasmonic nanostructures deposited on glass and covered with an amorphous silicon carbon layer allowing the reproducible fixation of glycan probes via robust covalent Si-C bonds[1] . Mannosides will be linked to the interface as model system for the selective interaction with the FimH lectins present on Escherichia coli. [2] Our first results of the optimization of the plasmonic layer based on gold and/or silver and their Raman effects will be presented. keywords : biochip, amorphous silicon carbon alloy, gold nanoparticles, glycan, bacteria [1] J. Yang et al., Anal. Chem. 2014, 86, 10340-10349 [2] P. Subramanian et al., ACS Appl. Mater. Interfaces 2014, 6, 5422−5431

Resume : Electrocorticography (ECoG) is a valuable tool used to investigate brain activity with a better spatial resolution compared to the EEG system. We describe the fabrication of new polyimide electrodes for EcoG recording, used to research the development of wake-sleep cycles in chicken embryos. The microelectrodes are connected to a dedicated system for data acquisition. Current ECoG recordings in birds are usually made with metallic wire electrodes placed on the dura surface though a hole on the skull. This approach is not reliable for long term acquisitions (a few days) as the electrodes may generate signal artefacts and cause bleeding. Recently, flexible polymer electrodes have been proposed to avoid the stiffness of the metal wire and to improve compliance with brain surface. The electrodes are fabricated on a 75µm thick polyimide film substrate. Gold lines are used as conductive wires to read the brain potentials and transfer them to the acquisition system. To protect and isolate gold tracks, a protective spinnable polyimide layer (Hitachi PI2610) is subsequently deposited. Then, an aluminium hard mask is deposited and patterned by a lithographic step, to protect and to open a window by oxygen plasma etch in the protective layers, so that the gold pads are exposed. Finally, the electrodes are ready and are detached from the carrier tape. Preliminary insertion tests have showed the feasibility of flexible electrodes insertion in the chicken brain.

Resume : The organic electronic ion pump (OEIP) has been developed as a tool which can deliver therapeutic substances locally and on-demand, avoiding many of the side-effects of systemic administration. OEIPs can be used to deliver ions and small molecules such as neurotransmitters with high spatial resolution to regulate cell activity locally. Because of the combined spatial and temporal precision, this is a technology with a promising future as an advanced therapeutic device. While OEIPs are designed to selectively deliver either cationic or anionic substances, they are not selective to specific cations or anions, resulting in dosage uncertainty – for example the ratio of H+ to cationic therapeutic is difficult to determine. This problem is particularly troubling since the array of “pumpable” substances can be broadened by shifting pH and pushing substances into a charged state above/below their pKa values. In the present work, we report on the investigation of the optimum pH value in the source ion reservoir that allows for the highest efficiency for the neurotransmitter GABA while limiting the delivery of H+. We further demonstrate the relationship between pH in the source, the model transport of GABA, and the resulting efficiency (electron:GABA and H+:GABA ratios).

Resume : The melanoma is one of the most aggressive human cancer types. Its malign nature is characterized by melanoma cells capacity of invading the tissue forming metastasis. We propose the development, fabrication and testing up to an integrated bio-chip proof of concept for monitoring the melanoma cells and bio-markers activity associated to the different development stages of the malign melanoma. The lab-on-a-chip design consists in the integration on the same microfluidic chip of two biosensors: an electrochemical biosensor with inter-digitized nano-electrodes and a plasmon resonance biosensor. The present microfluidic study is emphasizing the flow behavior of the fluid in different configurations of the microfluidic platform detection chamber. We report here a numerical investigation on the flow dynamics within a series of microchannels with integrated biosensors, presenting one inlet and one outlet. We have selected two configurations for results comparison: one “hele-shaw” type chamber with 500x30 um cross-section and one with 30x30 um cross-section. In both cases, the biosensors are placed in a row on the chamber bottom, covering the whole channel width. The predictions comparison was performed using pressure and velocity distributions and streamlines representations, among others. The largest influence on the flow dynamics is induced by the plasmon resonance biosensor’s pyramidal structures that can reach 5 um for the “hele-shaw” chamber.

Resume : Label-free DNA sensors based on sapphire substrate were fabricated and electrochemically characterized. A low resistivity (0.01-0.02 Ω cm) ptype Al2O3 wafer (100 orientation) was electrochemically anodized in an ethanoic hydrofluoric acid (HF) solution containing ethanol to construct the sapphire substrate layer with pore diameter of about 25 nm. The intrinsic negative charge of the DNA backbone was ex ploited to adsorb 26 base pairs of probe DNA (pDNA) into the PPy film by applying positive bias forming the nPS/PPy+pDNA layer. The plot of ip versus incubation time showed that current density (J) decreases by 46 μA cm^-2 per our. The sensitivity obtained from the plot of ip versus tDNA concentration is -166.6 μA cm^-2 μm^-1. Current density decreases with increasing incubation time and tDNA concentration. These results demonstrate that the sapphire substrate with PPy+pDNA+tDNA film has been successfully developed for a label-free DNA sensor in rapidly and specifically detecting select and threat agents.

Resume : Fighting blindness with retinal prostheses requires challenges not yet achieved: implanting a prosthesis (i) large enough to cover the retinal surface and (ii) embedding a high number of highly dense stimulatory elements. We developed an injectable, self-opening, and freestanding prosthesis restoring at least 40° of visual field, therefore covering a retinal surface of at least 12 mm in diameter. Moreover, the prosthesis has a hemispherical shape in order to minimize the distance from the targeted cells over its entire surface. It also operates according to a photovoltaic stimulation principle and it should be injected trough a minimal scleral incision. Our implant is based on PDMS as shell material, embedding 2345 organic photovoltaic stimulating pixels made of conjugated polymers (100 µm and 150 µm in diameter, density 54 px/mm2), with a biomimetic distribution in an active area of 13 mm (44° of visual field). Our results indicate that those pixels can deliver up to 54 mA/cm2 and generate an electrode potential of 182 mV when illuminated with a pulse light of 10 ms, 32 µW/mm2, at 530 nm. Accelerated aging tests and experiments with explanted retinas are currently under evaluation. These preliminary results show the potential of organic photovoltaics in the fabrication of a retinal prosthesis with large area and high stimulation efficiency. The biocompatibility and mechanical compliance of the materials represent a step forward in building advanced photovoltaic retinal prostheses.

Resume : Through our project we aim to develop an intelligent and trendy color capturing wrist band which tracks a persons vital stats such as Pulse Rate, Saturated peripheral oxygen and body temperature which alerts a nearby ambulance, doctors and next of kin in case of an emergency and sending location and condition of the patient through SMS and Voice call. This project has a wide social impact as continuous monitoring of patient vitals such as PR and SpO2, and swift communication to the guardian, ambulance and doctor increases chances of immediate medical aid to a patient in case of any anomaly. Hence, increases the chances of survival in case of an acute catastrophe. Also, it is designed keeping the trend in view, product changes it colors when is in contact with any fabric, object or human, blending in to that sensed color, also customizable, makes it much more fashionable and unnoticeable, which serve as a camouflage for military personnel.

Resume : In neuroprosthetics, prostheses with higher and denser electrodes are needed to obtain both more precise recordings and targeted stimulations. The main limit is the routing of the active sites to the electronic control unit. A solution is to place electrodes and connecting traces on different layers. A multi-layer approach allows the upscaling of electrodes number, thus increasing also their density. Nevertheless, a drawback of the multi-layer system is the passivation layer that increases the gap from the exposed electrode to the target tissue, especially when polymeric materials are used, such as PI or PDMS. For the layers placed more at the bottom, this gap may increase to undesired values. Indeed, the electrode-cell distance is one of the most important parameter affecting the spatial resolution and the efficiency in recording and stimulation. We introduced a new 3D design and microfabrication process, allowing all of the active sites to reach or even protrude the implant surface and traces to be placed in multi-layers. Our device may be fabricated on flexible and soft substrates, with arbitrary number of layers and arbitrary height of active sites. Bi-layer polyimide neural probes with Pt electrodes reaching 6 µm above the encapsulation layer were produced; the electrode size is 100 µm. Electrochemical characterizations show no significant differences between the multi-layer 3D shaped electrodes and planar monolayer electrodes. The average impedance at 1 kHz is 80 kOhm.

Resume : One of the latest trends in the fields of tissue engineering as well as oncological research is the development of in vitro systems mimicking specific target tissues. Indeed, there is an increasing demand for in vitro models recapitulating the tridimensional structure and microenvironment experienced by cells in the target. These systems would integrate the 2D systems employed so far. Interestingly, in addition to chemical and mechanical cues, certain tissues are known to be regulated by endogenous bioelectrical cues.[1] One such tissue is the bone. Indeed, it has been demonstrated to exhibit piezoelectric properties in vivo.[2] Electrical stimulation has been proven to sustain cell proliferation as well as to boost the expression of genes related to stem cells osteogenic differentiation and induce higher levels of enzymatic activities related to bone matrix deposition.[3] We present the development of a device consisting of a 3D electroactive porous scaffold based on the electrochemically active polymer PEDOT:PSS, allowing both cells proliferation monitoring and electrical stimulation for osteoregeneration studies. Indeed, organic electronic materials offer a unique combination of properties helping to transcend the current state of the art in transduction and stimulation of the electrical activity in cells. Among the above mentioned properties, their ability to conduct ions provide a lower impedance ‘connection’ to cells.[4] The material developed and device are anticipated to be beneficial for the study of the responses of multiple electroactive cell types in complex biomimicry environments. [1] Bassett, C.A.L., Pawluk, R. J. and Becker, R. O. Nature 204, 1964. [2] Fukada, K. and Yusada, I. J. Phys. Soc. JPN 12, 3, 1957. [3] Meng, S. et al. J. Bone Miner. Metab. 29, 2011. [4] Cui, X et al. Biomaterials 24, 2003.

Resume : Three of our five senses, namely touch, sight and hearing, have been commercialized in small powerful sensors and are ubiquitous in almost every electronic device including cell phones, laptops and tablets. The remaining two, smell and taste, pose a greater challenge for realization due to their intrinsic sensing mechanism and the required interface of biology and electronics. However, mastering these challenges will unravel a plethora of new applications ranging from point-of-care medical devices, artificial nose systems for environmental monitoring and live food quality control. Over the last few years graphene and other related 2D materials have emerged as promising materials capable of bridging this gap and paving the way towards a new generation of low-cost lab-on-a-chip type sensors paired with impressive performances. Herein, we report on lable-free electronic detection of DNA using various carbon sources (reduced graphene oxide, CVD graphene and CNT) as the semiconducting material and compare their performance as sensor material in an electrolyte-gated field-effect transistor configuration. Non-specific binding interactions are addressed by applying ultrathin atomic layer deposited passivation layers as well as pyrene-PEG ligands to shield the active carbon surface from unwanted matrix effects. TOF-SIMS, XPS, AFM and SEM investigations offer a comprehensive view on the molecular processes taking place at the sensor’s surface. Finally, we offer a satisfying theoretical explanation of the observed experimental data.

Resume : The growing interest in the field of biosensors requires devices able to interface biological media and to show operational robustness. Electrolyte-Gated Field-Effect Transistors (EGOFETs) have a wide range of applications due to their excellent sensitivity intrinsically intertwined with their capability of amplification. The device layout consists in a bottom-contact configuration along with a top gate electrode immersed in an electrolyte solution that guarantees the ionic contact with the semiconductor material. The electrolyte solution acts as gate dielectric, enabling to work at low-operational voltages due to the high capacitance (tens of μF/cm2) of the Electrical Double Layer (EDL). Here we present a novel EGOFET device based on a blended organic semiconductors processed by Bar-Assisted Meniscus Shearing (BAMS) technique. [1] BAMS allows one to deposit in one-step the blended material resulting in a smooth and crystalline thin-film surface. The electrical behavior of our EGOFETs was tested in bi-distilled water, a standard medium for evaluating device performances, and in NaCl solutions, an environment closer to real media.[2] Compared to state of the art, our devices reach excellent performances and exceptional water stability, which make them suitable for electrical transduction of biological signals. [1] F. Leonardi et al., Adv. Mater. 2016, 28, 10311. [2] Q. Zhang et al., Sci. Rep., 2016, 6, 39623.

Resume : Direct electrical detection of biotin-streptavidin binding with high sensitivity has recently been demonstrated using semiconductor nanowires and carbon nanotubes. However, there are some problems for realization of highly sensitive nanowire-based biosensor such as aligning nanowires on specific location with uniform interval and preventing nonspecific binding of the analytes. In this study, we describe a novel application for highly sensitive nano-biosensor based on DNA-templated gold nanowires (AuNWs) as the conducting channel to detect biotin-streptavidin binding. The DNA-templated AuNWs were manipulated by the positively charged gold nanoparticles (AuNPs) attached along λ-DNA molecules which were precisely positioned and uniformly separated on surface of large scale substrate by surface-patterning technique and connected between the source and drain electrodes with a gap of 50 nm. The positively charged AuNWs were employed to avoid nonspecific binding of streptavidin, with attachment of biotin to the layer for specific molecular recognition. We used atomic force microscopy (AFM) to observe the configuration of nano-biosensor based on the AuNWs and HP4145 semiconductor parameter analyzer to detect the change of its electrical conductivity by specific biotin-streptavidin binding. Specific biotin-streptavidin binding was detected by the change of current in the sensor characteristic. We confirmed that the nanodevice can be operated the highly sensitive nano-biosensor extending below the picomolar concentration regime after binding with streptavidin. This approach opens up for large scale fabrication of highly sensitive biomolecule sensor chips for potential use in medicine and biotechnology.

Resume : The paper describes shortly the behavior of microelectromechanical and thermoelectric hybrid generators that can harvest human body vibrations, movements from joints, respiratory rates and heat gradient between body and outside environment using combined piezoelectric,pyroelectric and thermoelectric materials.The aim was to find the best approach on how to efficiently harvest the entire human body energy. A voltage booster with two stages was manufactured in order to boost low voltage signals obtained from thermoelectric generators, from at least 100mV up to 5-18V in order to charge a supercapacitor that will be further used as a backup source for common electronic devices (mobile phones, lightning, radio). A separate DC/DC electronic converter for piezoelectric signals will be also considered.

Resume : An RFID-sensor assembly especially design for food freshness evaluation is presented. The gas sensor is based on graphene-polyaniline composite, assembled as sandwich structures and developed via plasma polymerization. The RFID component was developed using the “electronics on plastic” concept: laser engraving of the electronic circuit on Pyralux® support. The final assembly is similar to the two faces of a coin: on one side is the RFiD device and on the other side is the sensor; this design allows the sensor to be always in contact with the packaging atmosphere and detect the changes, while the RFID only collects and transmits the data. The assembly communicates with smart phones via a free application, which ensures friendly operation and easy handling for all consumers.

Resume : Three types of metalloporphyrins (Mn, Zn and Co) were tested as sensitive layer for the detection of histamine. A commercially available three-electrode screen printed sensor was modified with the porphyrin solution and electrochemically tested to various concentrations of histamine. A low strength acid was used as mediator of the reaction and also as extraction agent for the biogenic amines. Several samples of spoiled meat undergone an extraction step, to separate the biogenic amines and to test the sensors’ response to real samples. The sensitivity of the sensor was calculated to be equal to 5 ppm and the sensor exhibited promising results for the detection of histamine in the presence of other molecules in the extraction samples. A detection mechanism for the sensor was also proposed.

Resume : to be added

Resume : An acetone bio-sniffer (gas phase sensor) for evaluation of lipid metabolism utilizing reverse reaction of secondary alcohol dehydrogenase (S-ADH) was constructed and tested. The acetone sniffer was constructed for measure breath acetone for evaluating the lipid metabolism. NADH-dependent S-ADH can reduce acetone and meanwhile oxidase NADH to be NAD+. NADH has a fluorescent characteristics (ex: 340 nm, fl.: 490 nm). Thus, acetone concentration could be measured the decrease in NADH fluorescence intensity that is consumed by the enzymatic reaction of S-ADH. The acetone sniffer consisted of a NADH fluorescence measurement system, a flow-cell attaching on the fiber probe and an enzyme membrane. The NADH measurement system was composed of a UV-LED as the excitation light, band-pass filters and a photomultiplier tube (PMT). When the bio-sniffer contacted the gaseous acetone, the change of fluorescence would detect by the PMT. This acetone bio-sniffer showed highly sensitivity and selectivity. The dynamic range encompasses the concentration of gaseous acetone in exhaled breath (healthy people, diabetic patients). Finally, we applied the bio-sniffer to measure breath acetone. The results showed that the mean breath acetone concentration of fasting healthy volunteers were higher than those who did not have fasting. This acetone bio-sniffer provides a novel analytical tool for non-invasive evaluation of human lipid metabolism and monitoring of the progression of diabetes mellitus.

Resume : Carbon nanomaterials provide a new opportunity for next generation of electronics. Up to now, researchers have reported the carbon nanotube, graphene, as well as graphene derived materials (3D graphene foam and reduced graphene oxide etc) for flexible electronics. Our previous studies have demonstrated the free-standing ultrathin films of single-walled carbon nanotubes and reduced graphene oxide are great candidates for flexible pressure sensors and flexible non-contact sensing devices1,2. However, to improve the flexibility, sensitivity, transmittance, and stability towards commercialization, the new type of carbon materials or technology still urgently need to be developed. In this conference, we would like to report our recent progress in the synthesis of new type of carbon nanomaterials, including high crystallinity carbon patterns and self-crosslinked carbon arrays, and their applications in flexible sensing electronics3-5. We found that the special nanostructures such as self-crosslinked point and vertically aligned nanorods reduced the residual stress, and make carbon arrays based flexible devices possess high sensitivity and good stability (~10,000 times) in the detection of flexion and vibrations. Our findings indicate that the carbon nanomaterials are promising in flexible sensing electronics, and uncovered the capability of low-cost flexible sensors for early diagnosis of disease by monitoring the health-related physiological signals. Reference: 1, Xuewen Wang, Ting Zhang et al., Advanced Materials, 2014, 26, 1336-1342 (Cover) 2, Xuewen Wang, Zheng Liu, Ting Zhang et al., Advanced Materials, 2015, 27, 1370-1375 (Back cover) 3, Xuewen Wang, Ting Zhang, Zheng Liu et al., Science Advances, 2016, e1600209 4, Xuewen Wang, Ting Zhang, Zheng Liu et al., 2D Materials, 2017, Revised 5, Xuewen Wang, Ting Zhang, Zheng Liu et al., Submitted

Resume : Malaria is a continuing threat to global health, especially in developing countries. Among the several Plasmodium species that cause malaria in humans, P. falciparum is responsible for the most prevalent and dangerous form. Nearly 215 million malaria cases were registered in 2015, leading to more than half million deaths. Recent gains in reducing malaria incidence are currently under threat with the emergence of artemisinin resistant (Art-R) parasites. Thus, identifying people at risk and diagnosing patients reliably and quickly is critical to enable early treatment and limit spread of the disease. This project aims to develop a scalable, rapid, quantitative, label-free, sample-to-answer lab-on-a-chip (LOC) device for: (i) malaria detection (pan-Plasmodium genes), (ii) P. falciparum identification (specie-specific genes) and (iii) P. falciparum Art-R discrimination (drug resistance single nucleotide polymorphisms). Our approach relies on ultrasensitive, real-time isothermal DNA amplification coupled to complementary metal-oxide semiconductor (CMOS) based ion-sensitive field-effect transistors (ISFETs) as pH biosensors. We will explore the implementation of microfluidics that will enable single nucleic acid molecule detection and will facilitate its translation to the point-of-care (POC).

Resume : The race in biomedical diagnostics between optical detection principles (UV/Vis absorption, fluorescence, surface plasmon spectroscopy, etc.) and electrical/ electro-chemical/ electronic concepts has not been decided yet. Both approaches continue to offer solutions for fast, multiplexed, simple and cheap detection of oligonucleotides, PCR amplicons, genomic DNA (fragments), etc. Using graphene as both the channel material in transistor configurations as well as for SPR chips gives access to an unique analytical tool to investigate bioaffinity reactions at the same time from an electrical and optical point of view. It is well established that a significant change in the spatial organization of an aptamer upon ligand binding is leading to a massive change in the charge distribution at the surface. Hence, the graphene-FET (gFET) approach is a particular promising approach for bioanalyte detection as it translates this reorganization into a change in the surface double layer potential and thus into an easily detectable modulation of the source-drain current. In the case of graphene-based SPR signal enhancement can be achieved making it an attractive sensing platform [1-4]. However, one crucial step in the formation of a graphene-based sensor is the suppression of non-specific absorption. The results of an in depth investigation on graphene interfaces modified with pyrene ligands carrying COOH and PEG units on the absorption of lysozyme will be presented here. References: 1. Alsager, O.A.; Kumar, S.; Willmott, G.R.; McNatty, K.P., Small Molecule Detection in Solution via the Size Contraction Response of Aptamer Functionalized Nanoparticles, Biosens. Bioelectron. 57, 262-268 (2014). 2. Szunerits, S., Maalouli, N., Wijaya, E., Vilcot, J.-P., Boukherroub, R., Recent advances in the development of graphene- based surface plasmon resonance (SPR) interfaces, Anal. Bioanal. Chem. 405, 1435-1443 (2013). 3. Zagorodko, O., Spadavecchia, J., Yanguas Serrano, A., Larroulet, I., Pesquera, A., Zurutuza, A., Boukherroub, R., Szunerits, S., Highly sensitive detection of DNA hybridization on commercialized graphene coated surface plasmon resonance interfaces. Anal. Chem. 86, 11211-11216 (2014). 4. Singh, M., Holzinger, M., Tabrizian, M., Winters, S., Berner, N. C., Cosnier, S., Duesberg, G. S., Noncovalently functionalized monolayer graphene for sensitivity enhancement of surface plasmon resonance immunosensors, J. Am. Chem. Soc. 4;137(8), 2800-2803 (2015).

Resume : The analysis of Microbial Volatile Organic Compounds (MVOC) is an interesting way for microbiological diagnosis. Indeed the gases emitted by bacteria yields a fingerprint,so that a noninvasive detection and identification of pathogens is possible. The interest in the detection of these metabolites is therefore real in clinical diagnosis and industrial microbiology. The usual means of studying a volatile fraction is gas chromatography. This is efficient but costly. As an alternative, our optical sensors of MCOV are low-cost, but also fast and easy to use. They are made of porous oxides synthesized with sol-gel chemistry. Organic functional groups in these hybrid oxides tune pore diameter and surface properties. Detection through absorbance is simple : a colorimetric reading is enough and can be completed with spectrophotometry. Depending on the optical properties of the target gas, we designed xerogels with or without probe. Doping the porous xerogel with a probe is required when the target metabolite has no intrinsic optical properties in the visible range, such as indole Detection without probe gets possible when enzyme-generated MVOC are used as these gases are naturally colored. In this case, specificity is due to the chosen enzymatic activity. Some substrates releasing o-nitrophenol, made it possible to detect E.coli in food samples after 11 hours, starting from 100cfu/mL.

Resume : Reliable sensing of few bio-markers can revolutionize the current approach to early-diagnostics. Cells routinely do so by decoding the response mediated by millions of highly packed receptors residing on their surface. By this means, sperm cells sense few chemoattractants to localize the egg while rod cells on the retina respond to a single photon. Conversely, label-free single-molecule detection has been achieved so far by funneling a large number of ligands into sequences of single binding events through few recognition elements host on nanometric transducers. For instance, single DNA detection has been demonstrated using few bio-probes attached to a single nanotube transistor. This approach is inherently unable to track few cues in a milieu as either very high ligand concentrations or impractical long times are required. Conceptualizing cells’ ability to track recognition events at the physical limit, an electrolyte gated organic field-effect transistor bio-functionalized with highly packed antibodies is used. The selective and reliable electronic detection of a very low concentration of affinity ligands is demonstrated. The organic bioelectronic transistors used are mm-size, low-cost and are operated at physiologically relevant conditions setting the ground to a major revolution in immunoassays for early detection. no problem

Resume : The Water-Gated Organic Field-Effect Transistor (WGOFET) is one of the most promising device architecture for stimulating and recording cell electrophysiological activity given the possibility of biofunctionalization of the organic/electrolyte interface [1]. Here we present for the first time the use of two n-type PDI derivatives, named PDIF-CN2 and PDI8-CN2 [2], as active materials in WGOFETs. The two materials have identical solid-state arrangement but show two different growth mechanisms: almost-2D layer by layer for PDIF-CN2 and 3D for PDI8-CN2.The electron mobility of PDI8-CN2 shows a saturation with increasing the semiconductor layer thickness (~10-4 cm2/Vs at 10-15 nm). Differently from other semiconductors used in WGOFETs, whose mobility saturates after 1-2 monolayers from the interface, the PDIF-CN2 mobility increases unexpectedly with the semiconductor film thickness up to 35 nm while preserving an almost-2D growth modality, thus reaching values comparable to state-of-the-art p-type semiconducors (~10-3 cm2/Vs). From the cross-correlation of experimental and theoretical evidences, we can suggest that charge mobility increase is likely correlated to a bulk conduction contribution to the field-effect charge transport.These insights may enable the definition of a new material paradigm for the realization of performing WGOFETs for use in biological signal transduction. [1]S. Toffanin et al., J.Mater.Chem.B 1 (2013) 3850–3859 [2] X. Zhanet al., Adv.Mater.23 (2011) 268–284

Resume : A novel multi-responsive hydrogel has been synthetized by initiated chemical vapor deposition (iCVD). Hydrogels are known for their dynamic swelling response to aqueous environments. A chemical functionalization of the hydrogel surface was performed to add other stimuli-responsive functionalities and obtain a smart material that responds to two stimuli: light irradiation and exposure to aqueous environment. Modifying the hydrogel surface with solution-based methods is often problematic due to the damages caused by the permeation of solvents in the hydrogel. This issue is completely bypassed by the use of solvent-free techniques. Cross-linked polymers of 2-hydroxyethyl methacrylate (HEMA) were functionalized with azobenzene groups, as confirmed by IR spectroscopy and X-ray photoelectron spectroscopy (XPS). Through photoisomerization of the azobenzene, the polarity within the hydrogel is modified and as a consequence the affinity to water. Light irradiation modifies the degree of swelling within thin hydrogel films from 13% before exposure to UV light to 25% after exposure. The possibility of controlling the degree and rate of swelling by light irradiation was never reported before and can have exceptional implications for light-induced drug delivery or light-controlled microfluidic systems. The light-responsive hydrogels showed also biocompatibility and proton conductivity, which makes them suitable for a great variety of applications as biomaterials.

Resume : Organic electrochemical transistors (OECTs) are receiving a great deal of attention due to their ability to efficiently transduce biological signals. The working principle of OECTs relies on the modulation of the conductivity of the active material, which can be modified by electrochemical redox reactions in aqueous solution (doping/de-doping reactions). Recently, we have demonstrated the development of an ambipolar OECT with balanced charge transport characteristics [1]. The performance of the active material in OECTs depends on the capacitance per unit volume, a measure for how many charges can be added during the electrochemical doping reaction as well as the charge carrier mobility of these charges [2]. When the semiconducting polymers are deposited on a conductive substrate and a negative voltage is applied to reduce the polymer (vs Ag/AgCl), ions migrate into the active polymer layer to stabilise the charges on the polymer backbones. One of the most important material properties for efficient and reversible ion migration is the choice of the polymer side chains. We will present a series of semiconducting polymers and show the electrochemical doping reactions of these polymers in aqueous solution. In the polymers series, we changed the polarity of the side chains successively from hydrophobic to hydrophilic and compared their electrochemical doping properties in aqueous solution as well as their performance in n-type OECTs. In addition, we will present the development of a lactate sensor based on ambipolar semiconductors and show the advantages of this new class of material for bioelectronic applications. Reference [1] Giovannitti, A. et al. N-type organic electrochemical transistors with stability in water. Nat. Commun. 7, 13066 (2016). [2] Rivnay, J. et al. High-performance transistors for bioelectronics through tuning of channel thickness. Sci. Adv. 1, (2015).

Resume : We have developed pressure sensors that can mimic the skin properties in terms of flexibility, stretchability, self-healing and biodegradability. These developments have opened up new possibilities to enable sensing for prosthesis and implantable devices. In this talk, I will report our recent progress in related areas.

Resume : Organic electrochemical transistors (OECTs) have been proposed as biosensors for redox-active biomolecules thanks to their remarkable features such as signal amplification, very low operating potentials and adsorbed power. Nevertheless, the lack of selectivity hinders their widespread use in real-life applications. The selective detection of dopamine (DA), one of the most significant neurotransmitters in biological organisms, is currently a subject of significant interest. The rapid and accurate determination of DA is of great importance in the diagnosis of neurological disorders, such as Parkinson’s disease, autism, schizophrenia. However, the main problem related to the electrochemical detection of dopamine is that its oxidation potential is close to that of other endogenous substances such as uric acid (UA) and ascorbic acid (AA), which leads to poor selectivity and sensitivity in DA detection. We explored a new approach to selectively identify and determine the contributions of different analytes to the OECT electrical output signal through a potentiodynamic approach, by varying the operating gate voltage and the scan rate. A selective all PEDOT:PSS OECT has been developed (also fabricated directly onto textiles) with sensitivities and limits of detection comparable or even better than those obtained by Differential pulse voltammetry, a technique that employs a sophisticate read-out system that can hardly be considered a viable method in practical applications. [1] I. Gualandi, M. Marzocchi,E. Scavetta, M. Calienni, A. Bonfiglio, B. Fraboni: J. Materials Chemistry B 3, 6753-6762 (2015) [2] I.Gualandi, D.Tonelli, F.Mariani, E.Scavetta, M.Marzocchi, B.Fraboni Scientific Reports 6 35419 (2016)

Resume : In this study, fabrication and characterization of flexible sensors driven by piezoionic effect have been demonstrated. The ionic liquid-polyurethane (IL-PU) gels were prepared by casting the N,N-dimethylacetoamide (DMAC) solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]) and thermoplastic polyurethane. Then, poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) containing polyglycerin (PG) as stretchable electrodes were spray-deposited on both sides of the IL-PU gel. The sensor characteristics of the PEDOT:PSS-PG/IL-PU films were evaluated with a charge amplifier under bending using a mechanical tester. Upon bending the film, positive electric charges are rapidly generated, whereas the equivalent negative charges are formed when the bending stops. On the other hand, the opposite phenomenon was observed when the bent film recovers to the original straight shape, indicative of an acceleration sensor. Indeed, the electric charge increases in proportion to the acceleration, where the sensitivity was 5.3 nC/(m/s2). The value is three orders of magnitude higher than that of the commercial piezoelectric sensors. The mechanism can be explained in terms of the “piezoionic effect” based on the difference of ionic mobilities between the EMI+ and TFSI-. For example, upon bending the sensor, the EMI+ with higher mobility move toward anode due to the surface expansion, generating the positive electric charges. Then the electric charges decreased because the TFSI- follow afterwards. On the other hand, when the bending stops, polarization relaxation may cause negative electric charges in the same manner. Furthermore, various ILs with different alkyl chain lengths such as [EMI][TFSI], 1-buthyl-3-methylimidazolium bis(trifluoromethyl -sulfonyl)imide ([BMI][TFSI]), 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([HMI][TFSI]), and 1-methyl-3-octhylimidazolium bis(trifluoromethylsulfonyl)imide ([MOI][TFSI]) were investigated. Note that the longer the alkyl chains, the lower the transference number of cations. It is found that the electric charges generated by the bending increased in the order of [MOI][TFSI], [HMI][TFSI], [BMI][TFSI], and [EMI][TFSI] which is the same order of the transference number. Indeed, the generated electric charge are in proportion to the acceleration, where sensitivity increases with increasing the transference number of cations. This clearly shows that the mechanism of flexible sensors is based on the “piezoionic effect” of the IL-PU gel.

Resume : Ultra-flexible yet robust characteristic of materials has been desired in emerging soft systems. The flexibility is essential to minimize the gap, a major obstacle to collect signals or transfer matters in between the device and the biosurface. However, a solid becomes drastically weakened as the flexural rigidity decreases. Therefore, the flexural rigidity is limited to such level that the soft systems can be physically manipulated. Here we introduce new nonlinear framework that has both flexibility and robustness via multiplex lithography and dewetting-based molding process.[1,2] The flexibility and the robustness of the proposed framework lie in nonlinear correlation by means of the hierarchical design covering from macroscale to nanoscale. Consequently, it reversibly adheres along the arbitrary curvature by deforming their shape simultaneously. The optimized framework allows the structure to fit on the natural surfaces with assorted roughness, potentially providing a versatile strategy for zero-gap boundaries on complex biointerface. [1] Cho, Hyesung, et al. "Replication of flexible polymer membranes with geometry-controllable nano-apertures via a hierarchical mould-based dewetting." Nature communications 5 (2014). [2] Kim. et. al., "Nonlinear Frameworks for Reversible and Pluripotent Wetting on Topographic Surfaces", Advanced Materials, online published (2016)

Resume : Increasing interest in wearable electronics has sparked the rapid development of flexible conductors, mostly based on carbon nanomaterials – carbon nanotubes and graphene, due to their excellent electrical and mechanical properties. However, typical exfoliations and fabrications often reduce nano-fillers electrical conductivity (high shear force or chemical attacks) and stiffening of the composite (due to increasing filler content). A simple reductive dissolution method was applied to exfoliate carbon nanotubes and graphene to give individualised fillers in high yield. This charging method does not damage the carbon framework so the intrinsic high electrical conductivity can be retained. Instead of blending the solubilised fillers with a soft polymer matrix to give a standard conducting elastomer, a flexible porous polymer was used as a scaffold. The charged fillers were employed to impregnate a polyacrylate based poly-high internal phase emulsion (polyHIPE) to give a soft conducting composite (>1 S/cm). Individualised fillers diffuse into the pores of the polyHIPE to give an even distribution of the fillers while the negative charges help binding the fillers covalently to the scaffold. Since the fillers are only grafted onto the internal surface of the polymer, the softness of the polymer was preserved (E ~ 0.4 MPa). Such high conductivity and low modulus have only been achieved in low density carbon aerogels which require time consuming template synthesis. The conducting elastomer can be easily patterned by screen/syringe printing, or casted as a free-standing thin film. This flexible conductor is an excellent biomechanical strain sensor and is sensitive enough to distinguish test subjects from the same human motion.

Resume : We present a universal model for the transient drain current response in organic electrochemical transistors (OECTs). Using equivalent circuits and charge injection physics, we are able to predict the drain current in OECT devices upon application of a gate voltage input. The model is applicable to both plain and membrane-functionalized devices, and allows us to extract useful physical quantities such as resistances and capacitances, which are related to functional properties of the system. We are also able to use the model to reconstruct the magnitude and shape in time of an applied voltage source based on the observed drain current response. This was experimentally demonstrated for drain current measurements under an applied simulated action potential.

Resume : In this work, we present a process which allows the patterning of fully stretchable Organic Electrochemical Transistor (OECT) based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The sensor consists of an active stretchable area connected with stretchable metallic interconnections which can be assembled in a matrix. This device allows the development of an electronic skin, with enhanced sensing functionalities by recording in real-time physiological parameters such as heart rate, temperature and so on. This work is focused on fully stretchable sensors, meaning all the sensor parts are stretchable (to some extend). First, we have performed an optimization of horseshoes shape stretchable interconnections encapsulated in Polydimethylsiloxane (PDMS). We have developed an unique process in order to pattern Aluminum sheets by using a laser and a thermal release tape. The metallic interconnections present a stretchability up to 80 % without any increase of resistance. Then a photolithographic process has been developed in order to pattern the organic active area onto the PDMS and finally the formulation of a PEDOT:PSS has been tuned in order to get an active material with targeted stretchability up to 20%.

Resume : This paper presents a 24 um-pitch microelectrode array (MEA) with 6192 readout channels at 12 kHz and 23.2 uVrms of random noise. By using the MEA, we successfully measured the action potential of cardiac muscle cells. MEAs are used to record the action potentials of cultured cells, and the technology trend is tending towards larger arrays with larger numbers and higher densities of electrodes in order to gain an accurate understanding of more complicated cell characteristics. However, the trade-off between the array size and the speed or noise of the readout circuit has not yet been completely overcome in the previous reports. In this study, a value of 5.56 [(electrodes kHz)/(um2 uVrms)] is achieved in terms of the figure of merit, by utilizing the readout architecture of an active-pixel sensor (APS) with column-parallel analogue-to-digital converters (ADCs). Despite the simplicity of the readout circuit in each pixel, this value is close to that of the top-tier comprising around 10 [(electrodes kHz)/(um2 uVrms)], as recorded in previous reports with more complicated readout circuits. The in-pixel circuit comprises only two transistors for the amplifier and the array-scanning switch. This implementation of the readout circuit has the potential to improve the scalability of MEAs, because high-density and large-scale parallel readout can now be realized thanks to the small footprint of both the in-pixel amplifier and the peripheral ADC.

Resume : Molecular detection of biological molecules in liquid environments is an essential step in a wide variety of applications. Among the different types of devices proposed as possible liquid-phase sensors, Organic Electrochemical Transistors (OECTs) have recently attracted considerable attention because of their very low biasing voltages (< 1 V) and the intrinsic presence of an electrolyte. In this communication, we propose a novel strategy for the fabrication of OECTs on flexible, plastic substrates at ambient conditions and by exclusive means of inkjet-printing. Our devices were fabricated using a planar configuration by employing a commercially available PEDOT:PSS-based ink. The bulk Pt gate electrode, commonly used to catalyse the conversion of the analytes products into chemical species able to dedope the transistor’s channel, was replaced by a suspension of Pt nanoparticles dispersed into the PEDOT:PSS ink and subsequently inkjet-printed. Our tests proved that these inkjet-printed electrodes show excellent catalyst behaviour. To demonstrate the possibility of employing these OECTs as liquid-phase sensors, the devices were functionalised with glucose-oxidase and their performances as glucose sensors were investigated, obtaining a detectable response even at 0.1 mM concentrations. Our results could pave the way for the fabrication of the next generation of low-cost, flexible biochemical sensors.

Resume : An analysis of human and dog gene expression data derived from tumour and normal mammary glands indicated a significant overlap of genes. The aim of our work is to implement surface enhanced Raman scattering (SERS) in veterinary oncologic surgery and check if the marker like spectra found in human in vitro research [1] would match the findings in the dog study. The comparison between the Raman spectra of normal and malignant tissues demonstrates that strong signals from carotenoids (1158 cm−1 and 1520 cm−1 and at 1161 cm−1 and 1527 cm−1) are specific to healthy tissue whereas interfacial water (3311 cm-1) corresponds uniquely to malignancy. Direct ex vivo (no freezing, no staining, no conservation) samples of normal tissue, tumours, skin and pure fat from female dog patients were investigated following therapeutic mastectomy. The search for one or several markers to clearly differentiate between a normal and malignant status of a margin has required an extension of the spectral window up to 4000 cm-1 to accessing lines from fatty molecules (above 2200 cm-1) and interfacial water. We show that 632nm Raman excitation can provide fluorescence-free spectra of fresh ex vivo samples if appropriate substrates are employed. The concept of “comparative oncology” would allow cross progress in diagnostic, monitoring and therapies in human and veterinary medicine. Acknowledgements: PCCA 20/2014 & PN 5N_9/03/16 Romania [1] H. Abramczyk et al., Spectrochim. Acta Part A, 129 609–623, 2014

Resume : Significant advances have been made in the last two decades in interfacing electronic devices with the nervous system. Organic electronic materials in particular have emerged as ideal materials for interfacing with neurological systems due to their flexibility, biocompatibility and moreover their electronic and ionic conductivity. The ability to conduct ions confers a significant advantage over other electronic materials as organic electronics can in essence communicate in the native language of neurons via ionic currents. To that end, significant research efforts are being pursued to develop minimally invasive, implantable organic electronic devices integrating recording, stimulating, and drug delivery features. Here we demonstrate multimodal probes with the ability to record and stimulate neurons using low impedance PEDOT:PSS coated electrodes. Furthermore, we show that such devices can also incorporate organic electronic ion pumps for electrophoretic delivery of neurotransmitters with high spatial and temporal resolution. By using a novel vertical ion pump design with a fluidic reservoir along the length of the probe, the voltage needed to pump ions is reduced by more than 10 fold compared to previously reported ion pump platforms. The efficacy of the ion pumps is demonstrated in an epileptic neural network by delivering GABA to stop epileptic behavior in vivo. Due to the probes unique biocompatibility and being equipped with high-fidelity organic electronic devices, we anticipate this work to be the starting point for new stimulation, recording and drug delivery paradigms in chronic neural implantation.

Resume : Efficient electronic junctions were fabricated by covalent binding of photosynthetic reaction center proteins to metals, semiconductors polymer PEDOT:PSS and solid semiconductor ITO. The primary stages of photosynthesis take place in nanometric-size protein-chlorophyll complexes photosystem I (PSI). PSI generates a photovoltage of 1 V with an absorbed light-energy conversion efficiency of 47% (~23% solar energy) and a quantum efficiency of ~100%. The robust cyanobacterial PSI was used in the fabrication of optoelectronic devices by forming oriented multilayers from genetically engineered cysteine mutants. Oriented multilayers were fabrication by covalent binding of successive layers of PSI using cross-linking molecules. PSI layers were bond to metal and transparent conducting semiconductor electrodes under dry environment. The devices generated sizable photocurrent and photovoltage. The rate of photocurrent indicated the formation of a good electronic coupling between PSI and the electrodes. These devices can serve in the fabrication of hybrid bio-solid-state optoelectronic devices.