Electrochemical performance study of Ag/AgCl and Au flexible electrodes for unobtrusive monitoring of human biopotentials

Abstract Flexible and stretchable electronics are a logical choice for the recording of biopotentials, due to their improved patient comfort and customizability. There is, however, significant variance in the signal quality received from these electrodes based on material, size, and target recording frequency. Here we develop a methodology based on Electrochemical Impedance Spectroscopy (EIS) and circuit modeling for optimizing electrodes for a specific application. We use EIS to measure the frequency dependent impedance characteristics of gold (Au) and silver/silver chloride (Ag/AgCl) electrodes of different diameters. Additionally, we use a Randles circuit model and perform model fitting with our data to extrapolate results to arbitrary frequencies and diameters. We found that at low frequencies (