LAUSR

Capacitive electrocardiogram (cECG), as a revolutionized technique, offers an indirect skin contact and comfort measurement of the electrocardiogram (ECG) signal. However, it is also confronted with a relatively high skin-electrode interface impedance, which seriously affects the quality of acquired signals and limits its applications in practice. In this study, the critical factors that may influence skin-electrode interface impedance were investigated, including environmental humidity, clothing thickness, deformable supporting materials under electrodes, etc. To systematically evaluate the impact of these practical factors, we began from theoretical deduction and methodological calculation to quantitative cECG signal assessment. The theoretical deduction and methodological calculation not only clarify the impact of these factors on skin-electrode interface impedance but also suggest the optimal parameters of the environmental humidity, clothing thickness, and deformable supporting materials under electrodes. Subsequently, a series of experiments aimed at quantifying the skin-electrode interface impedance, while simultaneously capturing and analyzing cECG signals were conducted. Experimental results demonstrated environmental humidity, clothing thickness, and deformable supporting materials under electrodes have a significant impact on skin-electrode interface impedance and ECG signal quality. When the clothing thickness with fabric weight is 180 g/m2, the deformable supporting material is 3# [25% indentation force deflection (IFD)-128N, 40% IFD-186.5N, 65% IFD-320N], and the environmental relative humidity is 80%, the impedance and signal quality are the best. This study is expected to serve as a standardized procedure for exploring and assessing the efficient factors for noncontact cECG systems’ design and provide the foundation for practical applications.