Measurement of noise and impedance of dry and wet textile electrodes, and textile electrodes with hydrogel

Abstract

Textile sensors, when embedded into clothing, can provide new ways of monitoring physiological signals, and improve the usability and comfort of such monitoring systems in the areas of medical, occupational health and sports. However, good electrical and mechanical contact between the electrode and the skin is very important, as it often determines the quality of the signal. This paper introduces a study where the properties of dry textile electrodes, textile electrodes moistened with water, and textile electrodes covered with hydrogel were studied with five different electrode sizes. The aim was to study how the electrode size and preparation of the electrode (dry electrode/wet electrode/electrode covered with hydrogel membrane) affect the measurement noise, and the skin-electrode impedance. The measurement noise and skin-electrode impedance were determined from surface biopotential measurements. These preliminary results indicate that noise level increases as the electrode size decreases. The noise level is high in dry textile electrodes, as expected. Yet, the noise level of wet textile electrodes is quite low and similar to that of textile electrodes covered with hydrogel. Hydrogel does not seem to improve noise properties, however it may have effects on movement artifacts. Thus, it is feasible to use textile embedded sensors in physiological monitoring applications when moistening or hydrogel is applied.

Performance Evaluation of Five Types of Ag/AgCl Bio-Electrodes for Cerebral Electrical Impedance Tomography

“…25 They would consequently pollute the measured data and influence their precision. Therefore, an EIT electrode system with high SNR is preferable.…”

Electrochemical characterization of nanostructured Ag:TiN thin films produced by glancing angle deposition on polyurethane substrates for bio-electrode applications

“…Moreover, biopotential electrodes should also allow a clean signal transfer from the body to the recording apparatus, meaning that the threshold level of noise at the electrode/skin interface should be considerably lower than the signal amplitude [88,89,90,91]. Hence, the monitoring of the electrical noise of the films in contact with sweat in the frequency region of interest for the envisaged application (EEG) is of paramount importance, in order to assess the suitability of the developed GLAD sputtered Ag:TiN films to be used as biopotential electrodes.…”

Electrochemical and structural characterization of nanocomposite Agy:TiNx thin films for dry bioelectrodes: the effect of the N/Ti ratio and Ag content

“…Signal distortion caused by electrical noise addition to the monitored biopotential [49][50][51][52], coming from the contact of the electrode with a sweat layer and related with eventual corrosion processes, should be avoided. With that purpose, the power spectral density (PSD) of representative Ag y :TiN x couples of identical samples in synthetic sweat is patent in Fig.…”