Advanced sensor performance: Investigating complexities of electrical resistance relaxation behavior in piezoresistive materials

This study explores Multi-walled Carbon Nanotube (MWCNT)/Natural Rubber (NR) composites as flexible pressure sensors, focusing on electrical resistance relaxation under variable loads. Key parameters include applied load magnitude, duration, and post-load behavior. Circular buttons with MWCNT loadings of 6 phr and 7 phr, surpassing the percolation threshold, were fabricated and evaluated. Results showed a gauge factor of 321.2 ± 0.5 under 450% strain. Resistance variation at load lift-off exhibited enhanced sensitivity with higher MWCNT concentrations, showing a factor of 23 to 30 between 6- and 7-phr loadings. Upon load removal, a rapid increase in electrical resistance was followed by a gradual return to a steady state. Stabilization time increased with prolonged load application, while higher loads elevated steady-state resistance levels. These findings provide optimization strategies for improved sensitivity and responsiveness in flexible pressure sensor design.