A Comparative Study on the Effect of Electrode Materials in Conductive Sponge-Based Capacitive Sensors

Conductive sponge sensors have attracted growing interest for their high sensitivity, flexibility, ease of fabrication, and low cost—making them ideal for wearable electronics and posture monitoring systems. This study compares three electrode materials—aluminum, copper, and carbon nanotube (CNT) rubber—for use in conductive sponge sensors aimed at back posture detection. The sensors were evaluated based on mechanical properties such as compressive stress and strain, along with capacitance responses. Capacitance values, measured using Equation (3), ranged up to 9.5 F, 10.0 F, and 7.5 F for aluminum, copper, and CNT rubber electrodes, respectively, under controlled compression. Environmental testing under 30-cycle loading conditions demonstrated excellent signal stability and durability. Rapid response times were also observed during cyclic loading and unloading using a 5 kg weight (~ 5 kPa), mimicking real-world dynamic pressure. The results offer insight into optimizing electrode materials for sponge-based sensors and underscore their suitability for practical applications in posture monitoring, healthcare diagnostics, environmental sensing, and future wearable technologies.