Flexible pressure sensor based on CNTs/MS composite for health monitoring

Flexible sensors based on the piezoresistive principle are widely used in health monitoring and motion tracking due to their ability to accurately capture subtle pressure changes and their excellent conformability. However, designing flexible pressure sensors with high stability and a simple manufacturing process remains a significant challenge. In this study, a melamine sponge (MS) serves as the flexible substrate. A three-dimensional conductive network is constructed through the innovative incorporation of multi-walled carbon nanotubes (MWCNTs). Concurrently, the piezoresistive properties of the composite are significantly enhanced by introducing a dual-functional filler system comprising zinc oxide (ZnO) and conductive polyaniline (PANI). The material composition was optimized using an orthogonal experimental design. The fabricated sensor, based on the ZnO-PANI modified CNTs/MS composite, demonstrates a rapid response time of 60 ms(±3.1 ms) and a relaxation time of 50 ms(±4.3 ms). It exhibits a high sensitivity of 31.261 kPa^-1 (±0.3 kPa^-1) within a pressure range of 0-3 kPa. A pressure testing system incorporating an independent SDNT1608 thermistor was developed, enabling simultaneous acquisition of pressure and temperature parameters. Furthermore, this system preliminarily demonstrated the feasibility of real-time monitoring of various human physiological signals, including radial artery pulse waveforms, abdominal respiration, and joint movement, serving as a laboratory-level proof-of-concept for potential health monitoring.