High-performance pressure/strain sensors featuring a conductive network constructed from c-MWCNTs and nanospheres for human activity monitoring

Abstract

Human activity monitoring is a complex endeavor, which mainly depends on pressure or strain sensors. Therefore, the development of pressure/strain sensing composites is very valuable work. We prepared a composite to construct high-performance pressure/strain sensors for human activity monitoring. Benefiting from the excellent compression and tensile properties of thermoplastic polyurethane electrospun membrane (TPUEM), carboxylated multiwalled carbon nanotubes (c-MWCNTs) and poly(styrene-methacrylic acid)@polypyrrole nanospheres (PPNs) were anchored on the surface of TPU electrospun fibers by ultrasonication to form a dense multilayer conductive structure. The obtained composite (PPNs/c-MWCNTs/TPUEM) was assembled into a pressure sensor, with sensitivity as high as 14.16 kPa⁻¹ in the pressure range of 8.18–27.68 kPa, a sensing time of 223 ms, and good reliability (1800 cycles). Moreover, PPNs/c-MWCNT/TPUEM coated with low concentration PDMS also shows good tensile sensing and hydrophobicity. The tensile range of the assembled strain sensor is ∼100.0% and the gauge factor (GF) reaches 2.03. The contact angle (CA) of PDMS/PPNs/c-MWCNTs/TPUEM is near 138.6°. Owing to these properties, PPNs/c-MWCNT/TPUEM can monitor pressure/strain deformations caused by human movements and physiological activities, showing wide applications in the field of intelligent wearables.