Electrical characterization of electronic circuits produced by inkjet printing

Dissertação de Mestrado, Engenharia Electrónica e Telecomunicações, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014Impressão a jato de tinta tem atraído a atenção como uma nova tecnologia para a produção de dispositivos semicondutores, de grande área, a baixo custo. A eletrónica impressa irá ser fina, leve, flexível e inofensiva para o meio ambiente. Além disso, esta tecnologia possibilita a criação de uma ampla gama de componentes e circuitos eletrónicos que podem ser produzidos em massa e integrados em novas aplicações, como por exemplo nos dispositivos portáteis. Esta dissertação reflete o trabalho efetuado na caraterização elétrica de dispositivos eletrónicos impressos a jato de tinta. Resumidamente, dois tipos de dispositivos foram estudados: (a) transístores de efeito de campo em estrutura MIS (Metal-Isolador- Semicondutor) e (b) díodos retificadores. Foram abordados vários aspetos relacionados com os parâmetros individuais do dispositivo, nomeadamente, foi estudada a estabilidade operacional quando o dispositivo é sujeito a uso contínuo, efeitos de envelhecimento, variabilidade e escalabilidade. Foram fabricados e caracterizados circuitos lógicos de inversor e de porta NAND. Vários tipos de díodos retificadores foram avaliados em termos de resposta em frequência. Díodos Schottky, díodos compostos em estrutura MIS e transístores conetados como díodos. A propriedade incomum de retificação dos díodos em estrutura MIS é explicada. O díodo de tipo Schottky foi utilizado juntamente com um condensador impresso para montar um circuito retificador de meia-onda. Demonstra-se ainda, que este circuito é capaz de produzir um sinal DC retificado quando recebe na entrada uma onda sinusoidal com a frequência de 13.56 MHz. O uso deste circuito retificador como um bloco na construção de uma etiqueta de identificação por radiofrequência (RFID tag) é analisado.Ink-jet printing has been attracting attention as a new technology for low-cost, largearea production of semiconductor devices. Printed electronics will be thin, lightweight, flexible and environmentally friendly. Furthermore the technology enables a wide range of electrical components and circuits that can be massively produced and integrated in new applications such as wearable devices. This thesis reflects the work done in the electric characterization of electronic inkjet printed devices. Basically, two types of devices were studied: (a) metal-insulator semiconductor (MIS) field effect transistors and (b) rectifying diodes. We address several aspects related with individual device parameters, namely we studied the operational stability under continuous operation, ageing effects, variability and scalability. Inverter and NAND logic gate circuits were also fabricated and characterized. Several types of rectifying diodes were assessed in terms of their frequency response. Schottky type diodes, MIS capacitor diodes and diode connected transistors. The unusual rectifying property of MIS diodes is explained. The selected Schottky type diode, was used together with a printed capacitor to assemble a half-wave rectifying circuit. It is shown that this circuit provides a DC rectified signal when excited by a sinusoidal input at the frequency of 13.56 MHz. The use of this rectifying circuit as a building block for a radio frequency identification (RFID) tag is discussed

Graphene-Paper-Based Electrodes on Plastic and Textile Supports as New Platforms for Amperometric Biosensing

The possibility of exfoliating graphite into graphene sheets allows the researchers to produce a material, termed “graphene paper” (G-paper), conductive as graphite but more flexible and processable. G-paper is already used for electronic applications, like conductors, antennas, and heaters, outperforming metal conductors thanks to its high flexibility, lightness, chemical stability, and compatibility with polymeric substrates. Here, the effectiveness in the use of G-paper for the realization of electrodes on flexible plastic substrates and textiles, and their applicability as amperometric sensors are demonstrated. The performance of these devices is compared with commercial platforms made of carbon-based inks, finding that they outperform commercial devices in sensing nicotinamide adenine dinucleotide (NADH), a key molecule for enzymatic biosensing; the electrodes can achieve state-of-the-art sensitivity (107.2 μA mm−1 cm−2) and limit of detection (0.6 7 10−6 m) with no need of additional functionalization. Thanks to this property, the stable deposition of a suitable enzyme, namely lactate dehydrogenase, on the electrode surface is used as a proof of concept of the applicability of this new platform for the realization of a biosensor. The possibility of having a single material suitable for antennas, electronics, and now sensing opens new opportunities for smart fabrics in wearable electronic applications

Label-free immunodetection of α-synuclein by using a microfluidics coplanar electrolyte-gated organic field-effect transistor

The aggregation of α-synuclein is a critical event in the pathogenesis of neurological diseases, such as Parkinson or Alzheimer. Here, we present a label-free sensor based on an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) integrated with microfluidics that allows for the detection of amounts of α-synuclein in the range from 0.25 pM to 25 nM. The lower limit of detection (LOD) measures the potential of our integrated device as a tool for prognostics and diagnostics. In our device, the gate electrode is the effective sensing element as it is functionalised with anti-(α-synuclein) antibodies using a dual strategy: i) an amino-terminated self-assembled monolayer activated by glutaraldehyde, and ii) the His-tagged recombinant protein G. In both approaches, comparable sensitivity values were achieved, featuring very low LOD values at the sub-pM level. The microfluidics engineering is central to achieve a controlled functionalisation of the gate electrode and avoid contamination or physisorption on the organic semiconductor. The demonstrated sensing architecture, being a disposable stand-alone chip, can be operated as a point-of-care test, but also it might represent a promising label-free tool to explore in-vitro protein aggregation that takes place during the progression of neurodegenerative illnesses.This work was funded by the EXPLORA project MAT2015-72760-EXP (Spanish Ministry) and ERC StG 2012–306826 e-GAMES (European Research Council FP7). The authors also thank the Spanish Ministry of Economy and Competitiveness, through the projects FANCY CTQ2016-80030-R, GENESIS PID2019-111682RB-I00 and “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV-2015-0496), the Generalitat de Catalunya (2017-SGR-918) and the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN). S. R. is enrolled in the PhD program of the Universitat Autònoma of Barcelona (UAB). The research leading to these results has also received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007–2013) under Research Executive Agency Grant Agreement No. 600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. The Surface Plasmon Resonance (SPR) measurements were performed through the ICTS NANBIOSIS platform, more specifically in the Biodeposition and Biodetection Unit of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the Catalan Institute of Nanoscience and Nanotechnology (ICN2). The microfluidic device design and fabrication were performed with funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement 764281 (AiPBAND), and Marie Skłodowska-Curie grant agreement 813863 (BORGES).Peer reviewe

Harnessing Selectivity and Sensitivity in Electronic Biosensing: A Novel Lab-on-Chip Multigate Organic Transistor

Electrolyte gated organic transistors can operate as powerful ultrasensitive biosensors, and efforts are currently devoted to devising strategies for reducing the contribution of hardly avoidable, nonspecific interactions to their response, to ultimately harness selectivity in the detection process. We report a novel lab-on-a-chip device integrating a multigate electrolyte gated organic field-effect transistor (EGOFET) with a 6.5 μL microfluidics set up capable to provide an assessment of both the response reproducibility, by enabling measurement in triplicate, and of the device selectivity through the presence of an internal reference electrode. As proof-of-concept, we demonstrate the efficient operation of our pentacene based EGOFET sensing platform through the quantification of tumor necrosis factor alpha with a detection limit as low as 3 pM. Sensing of inflammatory cytokines, which also include TNFα, is of the outmost importance for monitoring a large number of diseases. The multiplexable organic electronic lab-on-chip provides a statistically solid, reliable, and selective response on microliters sample volumes on the minutes time scale, thus matching the relevant key-performance indicators required in point-of-care diagnostics