Flexible and robust dry electrodes based on electroconductive polymer spray-coated 3D porous graphene for long-term electrocardiogram signal monitoring system

In this study, highly flexible and conductive dry electrodes were developed using a biocompatible polymer (poly (ethylene dioxythiophene): poly (styrene sulfonate), (PEDOT:PSS)) loaded mechanically robust laser-induced graphene (LIG). The circular-shaped LIG electrode with an area of 0.7854 cm² was directly patterned using a CO₂ laser. The PEDOT:PSS was spray-coated on the LIG to enhance the electrical conductivity (164.2 Scm⁻¹) and electrode robustness. The prepared electrodes were characterized by the Field Emission Scanning Electron Microscope (FESEM), X-ray photoelectron spectroscopy (XPS), X-Ray Diffraction (XRD) and Raman Spectra. Experimental results showed that the surface resistivity and skin contact impedance of the electrode were 17.4 Ω/sq and 385 kΩ at 10 Hz. The impedance at the electrode–skin interface was relatively stable, thereby the SNR value of the electrocardiogram (ECG) signal obtained from the fabricated electrodes (12.9 dB) was comparable to Ag/AgCl electrodes (13.3 dB). The electrodes could be effectively and symmetrically attached to the skin since it is thin and flexible. The fabricated electrodes were successfully operated when the participant is resting, and fewer motion artifacts are observed during movement. Finally, ECG signals were demonstrated in a mobile application for real-time and long-term monitoring by attaching participants’ fingers with optimized dry electrodes.

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