Evaluation of Printed Silver/PEDOT:PSS Dry Electrodes for Pulse Wave Detection via Impedance Plethysmography Measurements

In this work, we developed a stretchable, screen printed dry electrode for impedance plethysmography (IPG) measurements using two different pastes: silver (Ag) and poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). A minimum number of layers were printed to get a uniform film after annealing to evaluate the electrical and electromechanical behavior of the related electrodes. Notably, the three layer Ag+PEDOT:PSS electrode exhibited increased sensitivity due to a higher initial sheet resistance (21.9 $\pm$ 0.03 $\Omega$/sq) and enhanced electrical contact between Ag and PEDOT:PSS films. 3-D surface profile measurements of the deposited layers revealed suitable distribution of the layers and tracks, with thickness reaching 90 $\mu$m, such as stretchable Ag paste (33.7 $\mu$m) and three layers of PEDOT:PSS (56.2 $\mu$m) after curing at a temperature of $\approx 120^\circ \text{C}$. Preliminary tests demonstrated that these electrodes can perform impedance plethysmography measurements and get waveforms comparable to those obtained with traditional disposable gel electrodes. This study highlights the potential of these IPG electrodes to be integrated into smart garments, enabling further in vivo measurements in patient monitoring, presenting a significant step toward practical healthcare applications.