Abstract: We report on the comparison between two different driving circuits for addressing micro-fabricated organic electrochemical transistors of different channel resistances and transconductance, aiming for neuromorphic sensing. The Wheatstone bridge configura tion shows interesting results by offering more versatility towards higher resistance materials. However, the Current-Voltage converter observed faster transients. Both circuits show different assets very encouraging for further practical application.

Abstract: The increasing popularity of machine learning solutions puts increasing restrictions on this field if it is to penetrate more aspects of life. In particular, energy efficiency and speed of operation is crucial, inter alia in portable medical devices. The Reservoir Computing (RC) paradigm poses as a solution to these issues through foundation of its operation - the reservoir of states. Adequate separation of input information translated into the internal state of the reservoir - whose connections do not need to be trained - allow to simplify the readout layer thus significantly accelerating the operation of the system. In this paper, the theoretical basis of RC was first described, followed by a description of its individual variants, their development and state-of-the-art applications in chemical sensing and metrology: detection of impedance changes and ion sensing. Presented results indicate applicability of reservoir computing for sensing and validating the SWEET algorithm experimentally.

Abstract: In the recent years, the organic electrochemical transistors (OECT) have attracted considerable attention for biosensing applications due to the biocompatibility of their materials and their low operating voltages. Upon exposure to an electrolyte, the dr ain current becomes ion-dependent. This can be exploited for sensing ion applications. To facilitate the process of designing such powerful ion sensing devices one needs the ability to simulate the transient dynamical behavior of many OECT elements conne cted in a network. We have developed a generic theoretical model of the OECT element that can be used for such purposes. Our OECT element resembles a typical FET three-port element with the response function parameterized with an additional time-dependen t variable, T, which describes how far the element operates from the stationary state. We have constructed a dynamical equation that describes how T changes in time when the element is exposed to arbitrary external voltages. This makes the element model highly interoperable with generic electrical circuit simulators. We provide an example of possible numerical implementation using the modified nodal analysis. We tested the underlying theoretical assumptions by comparing model predictions with experiment al data and found a reasonable agreement. Our model describes the typical current spikes observed in the literature.

Abstract: Organic electrochemical transistors offer powerful functionalities for biosensors and neuro-inspired electronics, with still much to understand on the time-dependent behavior of this electrochemical device. Here, we report on distributed-element modeling of the impedance of such micro-fabricated device, systematically performed under a large concentration variation for KCl_(aq) and CaCl_2(aq). We propose a new model which takes into account three main deviations to ideality, that wer e systematically observed, caused by both the materials and the device complexity, over large frequency range (1 Hz-1 MHz). More than introducing more freedom degree, the introduction of these non-redundant parameters and the study of their behaviors as function of the electrolyte concentration and applied voltage give a more detailed picture of the OECT working principles. This optimized model can be further useful for improving OECT performances in many applications (e.g. biosensors, neuro-inspired de vices, ...) and circuit simulations.