Body-Coupled Organic Electrochemical Transistors for Imperceptible Skin Bioelectronics

The efficient ion-to-electron transduction mechanism makes organic electrochemical transistors (OECTs) stand out for physiological sensing. Usually, OECT operations require saline solutions or hydrogels to function as the electrolytes; however, the wet electrolytes may compromise wear comfort and device stability for human-integrated applications. In this work, we propose a body-coupled OECT (b-OECT) device mechanism, where the skin and subcutaneous tissues act as natural electrolyte for the device operation. In the b-OECT, the organic semiconducting channel forms intimate and substrate-free contact with skins, enabling biofluid-derived ionic pathways to directly mediate gate-channel coupling and electrochemical modulation. The devices exhibit body-coupled transistor characteristics, skin-coupled operation, and ion-mediated neuromorphic-like conductance modulation. Without needing external supplied electrolytes, the b-OECT offers breathable and imperceptible body integration, where biological tissue directly participates in electrochemical signal transduction, opening potentials for skin-integrated bioelectronics and body-coupled neuromorphic biointerfaces.