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 (<1 Hz), Ag/AgCl had lower overall magnitude impedance than Au and at higher frequencies (1–1000 Hz), Au and Ag/AgCl performed similarly. Further, the magnitude impedance of the electrodes decreased linearly as electrode diameter increased. The methodology described in this study can be applicable to any customizable stretchable electronics fabrication process and enables design optimization for a target frequency, electrode size, and material.

Measurement of Cervical Neuronal Activity during Stress Challenge Using Novel Flexible Adhesive Surface Electrodes

“…Moreover, in addition to the observed group effect on neural firing (both during CPT and timed respiratory challenge), there was a significant group effect (CPTd vs. CPTi) on heart rate during the timed respiratory challenge (Supplemental Figure 1a). In the presented electrode device, both the electrode size and associated impedance, as well as the electrode shape and its arrangement on specific patterns can be customized 31 . This versatile electrode shaping can aid in neural structure source identification.…”

“…One basic requirement for spike sorting is the spatial relationship between channels. In the presented electrode device, both the electrode size and associated impedance, as well as the electrode shape and its arrangement on specific patterns can be customized 31 . This versatile electrode shaping can aid in neural structure source identification.…”

Measurement of Cervical Neuronal Activity during Stress Challenge Using Novel Flexible Adhesive Surface Electrodes

“…One basic requirement for spike sorting is the spatial relationship between channels. In the presented electrode device, both the electrode size and associated impedance, as well as the electrode shape and its arrangement on speci c patterns can be customized 31 . This versatile electrode shaping can aid in neural structure source identi cation.…”

A flexible adhesive surface electrode array capable of cervical electroneurography during a sequential autonomic stress challenge

“…The peel-and-stick device replaced the use of an invasive and cumbersome needle electrode. Because of the self-adhering and non-invasive design of the electrode array, the array enabled the measurement of electrical signals over a prolonged period 44 . In terms of structural benefit, the flexible sensory array enabled conformal contact with the human skin which will further reduce noise during recording.…”