PVA Electrospun Fibers Coated with PPy Nanoparticles for Wearable Strain Sensors

Abstract

Current conductive polymers win wide applications in smart strain–stress sensors, bioinspired actuators, and wearable electronics. This work investigates a novel strain sensor by using conductive polypyrrole (PPy) nanoparticles coated polyvinyl alcohol (PVA) fibers as matrix. The flexible, water‐resistant PVA fibers are initially prepared by combined electrospinning and annealing techniques, and then are coated with PPy nanoparticles through in situ polymerization. The resultant PPy@PVA fibers exhibit stable, favorable electrical conductivities due to the uniform point‐to‐point connections among PPy nanoparticles, e.g. after three‐time’ polymerizations, the PPy@PVA3 fiber film presents a sheet resistance of ≈840 Ω sq−1 and a bulk conductivity of ≈32.1 mS cm−1. Cyclic sensing tests reveal that, PPy@PVA sensors show linear relationships between the relative resistance variations and the applied strains, e.g. the linear deviation of PPy@PVA3 is only 0.9 % within 33 % strain. After long‐term stretching/releasing cycles, the PPy@PVA sensor exhibits stable, durable, and reversible sensing behaviors, no evident “drift” is observed over 1,000 cycles (5,000 seconds).