Design and Characterization of Screen-Printed Textile Electrodes for ECG Monitoring

This study was conducted to develop a screenprinted approach for the fabrication of textile electrodes and analyze their characteristic features for use as electrocardiography (ECG) signal sensors. The electrodes were obtained by printing poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) organic bio-compatible polymer-based ink on a finished fabric using a polyester mesh with 43 lines/cm. The physical-chemical properties of the polymer solution were varied to obtain a simple and reproducible fabrication process and a good electrode performance simultaneously. The electrode properties were first assessed by a benchtop measurement instrument and then on human subjects. Several tests under different conditions, for instance, by adding liquid and solid electrolytes, revealed that the electrodes possess the majority of characteristics required by the ANSI/AAMI EC12:2000 standard for gelled ECG electrodes. Furthermore, the benchtop measurements demonstrated that these electrodes preserve their electrical properties and functionality even after several washing cycles (performed under mild conditions), while they suffered physical stretching. While using some electrolytes, the skin contact impedance and the features extracted from the physiological signals were found to be highly similar to those obtained with disposable gelled Ag/AgCl electrodes (rho > 0.99). Through the proposed fabrication process, it is possible to change the electrical properties of a specific region of a finished fabric or a garment with an excellent geometrical resolution. This opportunity, along with the obtained results in terms of the electrical characteristics as ECG electrodes, indicates that the proposed approach could possibly be adopted in the future for the development of smart garments that could comfortably detect ECG signals.