Magnetically induced robust anisotropic structure of multi-walled carbon nanotubes/Ni for high-performance flexible strain sensor

Abstract

Multi-walled carbon nanotubes (MWCNTs) are widely used as functional nanomaterials in flexible strain sensing polymer composites. They are expected to exhibit high anisotropy when aligned along a certain direction due to their unique one-dimensional structure, which has a positive effect on enhancing the sensing performance of the original polymer composites. Here, we used a weak curing magnetic field (less than 0.7 T) to induce the self-assembly of MWCNTs in polymer composites to obtain a novel flexible strain sensor with anisotropic structure (MAPC). To further optimize the comprehensive sensing performance, the synergistic effect between MWCNTs and conductive particles was utilized to enhance the sensitivity of MAPC to tensile strain by filling a small amount of nickel nanoparticles (MAPCN). The sensor can measure the tensile strain range up to 720%, with high sensitivity (GF=1768.7, 90%–100% strain), fast response (loading delay time τ1 = 92.2 ms and unloading delay time τ2 = 143.6 ms, 0–10% strain), and high durability (1050 cycles at 10% strain). These important properties allowed MAPCN to accurately monitor human physiological activities, and a gesture recognition system was designed to demonstrate its practical value and potential application prospect in wearable devices.