Ambulatory Evaluation of ECG Signals Obtained Using Washable Textile-Based Electrodes Made with Chemically Modified PEDOT:PSS

Abstract

A development of washable PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) polyamide textile-based electrodes is an interesting alternative to the traditional Ag/AgCl disposable electrodes, usually used in clinical practice, helping to improve medical assessment and treatment before apparition or progress of patients’ cardiovascular symptoms. This study was conducted in order to determine whether physical properties of PEDOT:PSS had a significant impact on the coated electrode’s electrocardiogram (ECG) signal quality, particularly after 50 washing cycles in a domestic laundry machine. Tests performed, included the comparison of two PEDOT:PSS solutions, in term of viscosity with emphasis on wetting tests, including surface tension and contact angle measurements. In addition, polyamide textile fabrics were used as substrate to make thirty electrodes and to characterize the amount of PEDOT:PSS absorbed as a function of time. The results showed that surface tension of PEDOT:PSS had a significant impact on the wetting of polyamide textile fabric and consequently on the absorbed amount. In fact, lower values of surface tension of the solution lead to low values contact angles between PEDOT:PSS and textile fabric (good wettability). Before washing, no significant difference has been observed among signal-to-noise ratios measured (SNR) for coated electrodes by the two PEDOT:PSS solutions. However, after 50 washing cycles, SNR decreased strongly for electrodes coated by the solution that had low viscosity, since it contained less solid contents. That was confirmed by scanning electron microscopy images (SEM) and also by analyzing the color change of electrodes based on the calculation of CIELAB color space coordinates. Moreover, spectral power density of recorded ECG signals has been computed and presented. All cardiac waves were still visible in the ECG signals after 50 washing cycles. Furthermore, an experienced cardiologist considered that all the ECG signals acquired were acceptable. Accordingly, our newly developed polyamide textile-based electrodes seem to be suitable for long-term monitoring. The study also provided new insights into the better choice of PEDOT:PSS formulation as a function of a specific process in order to manufacture cheaper electrodes faster.

PEDOT:PSS-Based Conductive Textiles and Their Applications

“…The electrode was found to be capable of operating under both wet and dry conditions, which could be an important milestone in wearable monitoring of heart. Ankhili et al developed an ECG sensor electrode from a PEDOT:PSS screen-printed cotton fabric and obtained a clear ECG wave amplitudes up to 50 washing cycles [94]. The same group also produced washable screen-printed cotton textile electrodes with and without lycra of different PEDOT:PSS concentration, providing a medical quality ECG signal to be used for long-term ECG measurements with a similar result to silver-plated cotton fabric at 12.8 wt% of PEDOT:PSS to pure cotton [95].…”

Integration of Conductive Materials with Textile Structures, an Overview

“…Sensor: A sensor is an electronic component that detects or measures a physical property and tracks and records, indicates, or otherwise responds to it. Typical textile-integrated sensor types include textile electrodes for strain [7][8][9][10][11], electrocardiography [12][13][14][15][16], electromyography [17][18][19], electroencephalography [20][21][22], humidity [23][24][25][26], temperature [27,28], pressure [28][29][30], light [31,32], and molecule detection [33,34].…”

Washable embroidered textile electrodes for long-term electrocardiography monitoring

“…In order to confirm the influence of washing on ECG signal quality, the power spectral densities have also been evaluated. Figures 10, 11 and Figure 12 show that the density in the important frequency domain (<5 Hz) has not been strongly degraded [14]4-ethylenedioxythiophene. Moreover, after 50 cycles of washing, the power spectral density decreased from unwashed bands except band made by Madeira conductive yarn protected by nonconductive yarn (Figure 12b) when there is not obviously difference between the signal from unwashed and from 50 washing cycle bands.…”