Electrochemical Characteristics Based on Skin-Electrode Contact Pressure for Dry Biomedical Electrodes and the Application to Wearable ECG Signal Acquisition

Jinzhong Song,Zhongping Cao,Jianping Guo,Ruoxi Liu,Jingsong Li,Chuang Yu,Zhonggang Liang,Tianshu Zhou,Qingjun Liu,Xinming Yu,Ying-Ren Chien

doi:10.1155/2021/7741881

Abstract

Based on one simulated skin-electrode electrochemical interface, some electrochemical characteristics based on skin-electrode contact pressure (SECP) for dry biomedical electrodes were analysed and applied in this research. First, 14 electrochemical characteristics including 2 static impedance (SI) characteristics, 11 alternating current impedance (ACI) characteristics and one polarization voltage (PV), and 4 SECP characteristics were extracted in one electrochemical evaluation platform, and their correlation trends were statistically analysed. Second, dry biomedical electrode samples developed by the company and the laboratory, including textile electrodes, Apple watch, AMAZFIT rice health bracelet 1S, and stainless steel electrodes, were placed horizontally and vertically on the “skin” surface of the electrochemical evaluation platform, whose polarization voltages were quantitatively analysed. Third, electrocardiogram (ECG) collection circuits based on an impedance transformation (IT) circuit for textile electrodes were designed, and a wearable ECG acquisition device was designed, which could obtain complete ECG signals. Experimental results showed SECP characteristics for dry electrodes had good correlations with static impedance and ACI characteristics and the better correlation values among 2-10 Hz. In addition, polarization voltages in vertical state were smaller in horizontal state for dry biomedical electrodes, and polarization voltage of electrode pair (PVEP) values for Apple watch bottom was always smaller than ones for Apple watch crown and LMF-2 textile electrode. And the skin-electrode contact impedance of IT textile electrodes was less than the traditional textile electrodes.

Highlights

With the development of biomedical engineering technologies, the need for low-load, noninvasive medical supervision is becoming more and more prominent
The front of the garment for the wearable ECG signal acquisition is showed in Figure 17(a), and the reverse of the wearable ECG signal acquisition garment is showed in Figure 17(b), which combined impedance transformation (IT) electrodes, ECG lead lines, and ECG acquisition device
Based on a variety of biomedical electrodes developed by the company and the laboratory, including 3M ECG electrode, textile electrodes, Apple watch, AMAZFIT rice health bracelet 1S, and stainless steel electrodes, correlations between electrochemical characteristics and skin-electrode contact pressure were analysed

Summary

Introduction

With the development of biomedical engineering technologies, the need for low-load, noninvasive medical supervision is becoming more and more prominent. Biomedical signals (such as ECG, EMG, EEG, and EOG) were usually used to evaluate cardiovascular and other functions for human bodies widely, which was usually extracted by traditional wet paste electrodes (Ag/AgCl) nowadays. While it presents many problems [1, 2], for example, it needs to stick to the skin and causes allergic reaction. Dry biomedical electrode, as one new biosensor, has attracted researchers’ attention because they can obtain. Journal of Sensors biomedical signals from human bodies with some advantages such as without glues, reused, convenient to find the location, and very useful for wearable health monitoring. Stainless-steel dry electrode is mainly composed of a stainless-steel sheet plated with Ag/AgCl, which is used to extract ECG signals from human body surface according to touching the skin directly without conductive paste

Methods

Results

Conclusion