Ultra-Conformal Skin Electrodes with Synergistically Enhanced Conductivity for Low-Motion Artifact Epidermal Electrophysiology

Abstract Accurate and imperceptible monitoring of electrophysiological signals is of primary importance for wearable healthcare. Stiff and bulky pregelled electrodes are now commonly used in clinical diagnosis, causing severe discomfort to users as well as artifact signals in motion. Here, we report a ~ 100 nm ultrathin dry epidermal electrode that is able to conformably adhere to skin and accurately measure electrophysiological signals. This dry epidermal electrode was fabricated by direct transfer of Chemical Vapor Deposition (CVD) - grown graphene (~ 1 nm) by poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS, ~ 100 nm) as the transfer medium, namely PTG. It showed low sheet resistance (45 Ω/sq), high transparency (80%), and mechano-electrical stability. The enhanced optoelectronic performance was due to the synergistic effect between graphene and PEDOT:PSS, which induced a high degree of molecular ordering on PEDOT and charge transfer on graphene by strong π-π interaction. Together with ultra-thin nature, PTG exhibited a low electrochemical impedance when interfacing with skin, thereby leading to accurate electrophysiological signal detection with low motion artifact, as well as controlling robotic claws. This strategy to synergistically incorporate graphene and PEDOT:PSS together as ultra-conformal dry electrodes will have a significant impact on the development of epidermal electronics.