A Flexible and Switch-Matrix-Addressable Active Electrode Array Based on Complementary Organic Electrochemical Transistor and p-n Diode Technology

Due to their effective ionic-to-electronic signal conversion and mechanical flexibility, organic neural implants hold considerable promise for biocompatible neural interfaces. Current approaches are, however, primarily limited to passive electrodes due to a lack of circuit components to realize complex active circuits at the front-end. Here, we introduce a p-n organic electrochemical diode (OED) using complementary p- and n-type conducting polymer films embedded in a 15-μm -diameter vertical stack. Leveraging the efficient motion of encapsulated cations inside this polymer stack and the opposite doping mechanisms of the constituent polymers, we demonstrate high current rectification ratios and fast switching speeds. We integrate p-n OEDs with organic electrochemical transistors (OECT) in the front-end pixel of a recording array. This configuration facilitates the access of OECT output currents within a large network operating in the same electrolyte, while minimizing crosstalk and interference from neighboring elements. We further demonstrate it to generate time-division-multiplexed amplifier arrays. When fabricated in a shank format, this technology enables the multiplexing of amplified local field potentials directly in the active recording pixel in a minimally invasive form factor.