Three-dimensional CNT-rGO/PDMS porous scaffold derived supercompressible lightweight body-mounted piezoresistive force sensor for human motion monitoring

Abstract

Wearable electronics is an emerging field that demands composites with both reliable mechanical durability and suitable electrical sensitivity. Herein, we report a combination of supercompressible, ultralightweight, piezoresistive and mechanically robust sensor created by the infiltration of active fillers (CNTs/rGO) on the 3D porous scaffold of PDMS. Carbon nanotubes (CNTs) and reduced graphene oxide (rGO) hybrid synergistically improve the electrical and sensing properties by providing better interfacial contacts, high electron/phonon transfer; low inter tube slippage and reduction in phonon scattering. This study provides useful insights and experimental optimisation of parameters like dropping time and nanofiller concentrations to generate highly viable hybrid microstructure for sensor applications. The sensor shows excellent peizoresistive performance like wide linearity range, large-scale force sensing, supercompressibility, good durability, rapid response-recovery time and good sensitivity. The multifunctional sensor exhibits promising potential for the real-time monitoring of human flexion, like joint movements of finger, wrist, elbow and knee. It can directly be integrated on a shoe sole for reliable real-time gait monitoring. The smart insole could accurately monitor and distinguish gait phase while walking, jogging, squatting, sitting, standing. Based on the versatility of the sensor and the ability to accurately evaluate gait speed, stride length the sensor can be employed for bio-motion analysis, myoelectric prosthesis and other wearable devices.