Organic electrochemical transistors (OECTs) have gained considerable interest for applications in bioelectronics, neuromorphic computing, and logic circuitry. Their defining characteristic is the bulk-modulation of channel conductance owing to the facile penetration of ions into the (semi)conducting polymeric channel. In the realm of bioelectronics, OECTs have shown promise as amplifying transducers due to their stability in aqueous conditions and high transconductance. These devices can be fabricated in conformable form factors for in vivo stimulation/recording, and for cutaneous EEG and ECG recordings in human subjects. The performance of these devices, their operating conditions, and suitability for certain applications is linked intimately with their form factor and the transport properties of the active materials. In this work we show how thickness can be used to design optimal devices for a range of electrophysiological recording applications. Scaling of device performance with geometry reveals the importance of the active material’s mobility and charge storage capacity (per unit volume) in benchmarking new materials. Such findings have led to the development of a new class of polymers which outperform prototypical conducting polymers (i.e. PEDOT:PSS), and can potentially open new paths for the utility of OECTs in a number of application areas.
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