Ultrastrong, highly conductive and capacitive hydrogel electrode for electron-ion transduction

Abstract

<h2>Summary</h2> Electron-ion transduction is the cornerstone for promoting emerging ionotronic devices, ranging from basic electronic elements to bioelectronics. However, with commonly used metal electrodes, the electron-ion transduction suffers from high impedance, signal distortion, and poor voltage tolerance. Conductive porous electrodes could partially remedy these issues but are accompanied by mechanical weakness. Herein, a general strategy is discovered to ameliorate these issues by introducing a conducting polymer hydrogel electrode of ultrahigh strength and conductivity with a capacitive behavior. These features are derived from a nanoporous conductive matrix that has π-π interactions as both cross-linking sites and electron-transfer pathways and is formed through surface gelation coupled with chemical treatment and controlled densification. This strategy significantly decreases the low-frequency impedance and improves the signal fidelity, without affecting its high-frequency response. Furthermore, excellent biocompatibility and multifunctionality have also been demonstrated, showing the great potential of this strategy for bioelectronic applications and human-machine interfaces.