Evolution of OECT Devices Towards Adaptive Fast High-Amplification Sensors

Over the last two decades, organic electrochemical transistors (OECTs) have risen in popularity and have seen applications in various fields. They are especially interesting for bioelectronic applications because of their biocompatible properties and electrical amplification capability. Like most conventional solid state transistors these devices work by modulating the conductivity of an electrical channel by means of a third terminal, the gate. However, unlike most solid state transistors the channel and the gate of an OECT comprise of an interplay between electrons, holes, and ionic fluxes within organic mixed conductor materials and electrolytes. The dynamics of the OECTs are consequently rather complex in their description, which was attempted to be captured in models by various research groups over the years. Here we take the audience through the history of some of the seminal models that were presented, in an attempt to illustrate the evolution of the OECT models. Along the way an interactive summary arises of the major modeling milestones, providing an overview of our knowledge on OECT device physics. We end the journey with some results from new experimental devices that were specifically designed for neural sensing. Although these devices might be optimized for sensing, they will also give us new insights into the potentially simultaneously usable neuromorphic capabilities of these fast switching OECTs that intended for bio-interfacing. This work will therefore pave the way towards the close integration of organic neuromorphic devices and high amplification fast biopotential sensors.