Logic Circuits Featuring Organic Electrochemical Transistors: What is the Logic Behind OECTs in Logic?

For bioelectronic applications, the optimal electronic device is one capable of effectively interfacing with living systems by coupling electronic conduction and the ionic conduction which underlies signal transmission in physiological environments. In this context, the organic electrochemical transistor (OECT), which has a conjugated polymer-based active channel, is a promising device since the conjugated polymer can feature mixed ionic-electronic conduction in aqueous electrolytes. Having gained a solid understanding of the OECT and its operational fundamentals, research has now shifted towards integrating the OECT as a building block in logic circuits; which are featured in this review due to the advanced functionalities they enable. First, a brief overview of OECT's key parameters and advantages are presented. Next, the integration of OECTs in unipolar and complementary configurations is discussed. This is followed by examples demonstrating the implementation of these circuits along with their defining characteristics. Finally, a brief overview highlights the key challenges that must be addressed to enable the development of more complex OECT-based circuitry capable not only of transducing bio-signals but also processing them. OECT-based circuits represent a solution for applications requiring soft and flexible electronic devices and provide a valid alternative to inorganic technologies at the bio-interface.