Transistors as an Emerging Platform for Portable Amplified Biodetection in Preventive Personalized Point‐of‐Care Testing

The impressive improvement in biomolecular detection has gone from simple chemical methods to sophisticated high throughput laboratory machines capable of accurately measuring the complex biological components and interactions. In the following chapter, we focus our attention on transistor‐based devices as an emerging platform for easy‐to‐use, portable amplified biodetection for preventive personalized medical applications and point‐of‐care testing. Electronic sensing devices comprise biosensors based on field‐effect transistors (bio‐FETs) and organic electrochemical transistors (OECTs). Transistor sensing devices can transduce electronic and ionic signals thereby creating an effective human‐machine communication channel. In this chapter, we survey the progress done on the development of transistor innovative concepts to examine biological processes, i.e., biosensors integrated with textiles, flexible substrates, and biocompatible materials. Electrochemical and field‐effect transistors can operate at low voltages possibly serving for highly sensitive, selective, and real‐time sensing devices. The exploration of biosensors integrates different disciplines such as organic electronics, biology, electrochemistry, and materials science

Organic Transistors Making Use of Room Temperature Ionic Liquids as Gating Medium

La capacité de transport ionique et électronique des couches minces organiques semiconductrices et conductrices est particulièrement intéressante dans le domaine de l’électronique imprimable et flexible. L’incorporation d’un électrolyte en tant que milieu de grille dans les transistors organiques (Transistors EG), permet de moduler le courant en plusieurs ordres de grandeur à une tension relativement basse (<2 V) grâce à la capacitance exceptionnelle de l'interface du canal/électrolyte, déterminée par les faibles épaisseurs de la double couche électrique qui se forme à l’interface électrolyte/couche mince organique. Les liquides ioniques, soit des sels fondus à des températures inférieures à 100 °C, sont intéressants pour leur grande stabilité électrochimique (leur fenêtre de stabilité s’étend jusqu’à 5 V) et leur bonne conductivité ionique (1-15 mS cm-1). La principale motivation derrière le présent travail est de démontrer un fonctionnement à faible tension des transistors organiques en faisant usage des liquides ioniques, en tant que milieu de grille. Tout d'abord, nous avons établi l'importance de la nature et morphologie de l’électrode de grille sur la performance des transistors électrochimiques. L’utilisation de carbone actif à haute aire de surface comme électrode de grille limite des processus électrochimiques indésirables à l’interface électrolyte/grille et rend inutile la présence d'une électrode de référence pour contrôler le potentiel du canal. Ceci a été démontré en utilisant des électrodes de grille en carbone actif, le polymère semiconducteur MEH-PPV comme matériel du canal et le liquide ionique [EMIM][TFSI] en tant que milieu de grille. L’utilisation de carbone actif avec une aire de surface non-limitative en termes de sa capacité à fournir la charge nécessaire pour moduler la conductivité du canal du transistor, a entraîné un voltage d’opération en dessous de 1 V et une mobilité des porteurs charge de (1,0 ± 0,5) × 10-2 cm2V-1s-1. Un défi dans le domaine des transistors électrochimiques est d'améliorer le temps de réponse, qui est une conséquence du temps nécessaire pour la redistribution des ions dans le canal du transistor à l’application d’un biais électrique.----------Abstract The ability to couple ionic and electronic transport in organic transistors, based on π conjugated organic materials for the transistor channel, can be particularly interesting to achieve low voltage transistor operation, i.e. below 1 V. The operation voltage in typical organic transistors based on conventional dielectrics (200 nm thick SiO2) is commonly higher than 10 V. Electrolyte-gated (EG) transistors, i.e. employing an electrolyte as the gating medium, permit current modulations of several orders of magnitude at relatively low gate voltages thanks to the exceptionally high capacitance at the electrolyte/transistor channel interface, in turn due to the low thickness (ca. 3 nm) of the electrical double layers forming at the electrolyte/semiconductor interface. Electrolytes based on room temperature ionic liquids (RTILs) are promising in EG transistor applications for their high electrochemical stability and good ionic conductivity. The main motivation behind this work is to achieve low voltage operation in organic transistors by making use of RTILs as gating medium. First we demonstrate the importance of the gate electrode material in the EG transistor performance. The use of high surface area carbon gate electrodes limits undesirable electrochemical processes and renders unnecessary the presence of a reference electrode to monitor the channel potential. This was demonstrated using activated carbon as gate electrode, the electronic conducting polymer MEH-PPV, poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene] channel material, and the ionic liquid [EMIM][TFSI] (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), as gating medium. Using high surface area gate electrodes resulted in sub-1 V operation and charge carrier mobilities of (1.0 ± 0.5) ×10-2 cm2V-1s-1. A challenge in the field of EG transistors is to decrease their response time, a consequence of the slow ion redistribution in the transistor channel upon application of electric biases. We systematically investigated EG transistors employing RTILs belonging to the same family, i.e. based on a common anion and different cations. The transistor characteristics showed a limited cation influence in establishing the p-type doping of the conducting polymer. Interestingly, we observed that the transistor response time depends on at least two processes: the redistribution of ions from the electrolyte into the transistor channel, affecting the gate-source current (Igs); and the redistribution of charges in the transistor channel, affecting the drain-source current (Ids), as a vii function of time

Tackling the Problem of Dangerous Radiation Levels with Organic Field-Effect Transistors

Accurate, quantitative measurements of ionizing radiation, commonly employed in medical diagnostic and therapeutic applications are essential prerequisites to minimize exposure risks. Common examples of radiation detectors include ionization chambers, thermoluminescent dosimeters, and various semiconductor detectors. Semiconductor dosimeters such as p/n type silicon diodes and MOSFETs have found widespread adoption due to their high sensitivity and easy processing. A significant limitation of these devices, however, is their lack of tissue equivalence. The high atomic number (relative to soft tissue) of silicon causes these devices to over-respond to photon beams that include a significant low energy component, for example, 1–10 kV, due to an enhanced photoelectric interaction coefficient. Organic field effect transistors (OFETs) are capable of providing tissue equivalent response to ionizing radiation in order to monitor more accurately the risk of exposure in medical treatments. This chapter presents the possibility to use different types of OFETs as ionizing and X-ray radiation dosimeters in medical applications

Sex- and age-related differences in the management and outcomes of chronic heart failure: an analysis of patients from the ESC HFA EORP Heart Failure Long-Term Registry

Aims: This study aimed to assess age- and sex-related differences in management and 1-year risk for all-cause mortality and hospitalization in chronic heart failure (HF) patients. Methods and results: Of 16 354 patients included in the European Society of Cardiology Heart Failure Long-Term Registry, 9428 chronic HF patients were analysed [median age: 66 years; 28.5% women; mean left ventricular ejection fraction (LVEF) 37%]. Rates of use of guideline-directed medical therapy (GDMT) were high (angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers and mineralocorticoid receptor antagonists: 85.7%, 88.7% and 58.8%, respectively). Crude GDMT utilization rates were lower in women than in men (all differences: P\ua0 64 0.001), and GDMT use became lower with ageing in both sexes, at baseline and at 1-year follow-up. Sex was not an independent predictor of GDMT prescription; however, age >75 years was a significant predictor of GDMT underutilization. Rates of all-cause mortality were lower in women than in men (7.1% vs. 8.7%; P\ua0=\ua00.015), as were rates of all-cause hospitalization (21.9% vs. 27.3%; P\ua075 years. Conclusions: There was a decline in GDMT use with advanced age in both sexes. Sex was not an independent predictor of GDMT or adverse outcomes. However, age >75 years independently predicted lower GDMT use and higher all-cause mortality in patients with LVEF 6445%

Incorporating aligned carbon nanotube electrode arrays in organic thin-film transistors

We introduce a very simple technique to obtain aligned carbon nanotube arrays tested in organic thin-film transistors based on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) as the organic semiconductor. The technique to prepare aligned CNT electrode arrays was simple and resulted in organic thin-film transistors with a higher drain-source current and lower threshold voltage proving their effectiveness as injection electrodes. We believe that the aligned carbon nanotube electrode array can find important applications in organic microelectronic and biosensor devices