Venus flytrap-inspired PVDF-based sensitive strain sensor with modulus-tuned design for anisotropic bending recognition

Abstract

Polyvinylidene fluoride (PVDF) has attracted extensive attention for flexible piezoelectric strain sensors due to its piezoelectric activity and mechanical robustness. However, practical application in small-strain monitoring occasions remains restricted by limitations such as low intrinsic piezoelectricity. Inspired by the mechanical structure of Venus flytrap's trigger hairs, this study synergistically combines modulus differentiation mechanisms with a coaxial architecture to develop core–shell nanofibers. The fiber structure comprises a rigid Polyamide 66 (PA66) core, a flexible PVDF sensing layer as the outer shell, and polydopamine-modified BaTiO₃ nanoparticles (PBTO) distributed within the outer sheath. These bioinspired fibers feature a radial stiffness-flexibility combination to achieve directional stress transmission. The modified nanofiber membrane achieves an 840% enhancement in voltage output compared to pure PVDF, demonstrating bending sensitivity of Gauge Factor (GF) 221.4 and only 0.67% signal attenuation over 12 000 cyclic tests. Leveraging this amplification mechanism, the core–shell nanofibers have been engineered into bending vector sensors capable of discerning wind velocity magnitude and directional parameters. This approach shows potential for optimizing unmanned aerial vehicle flight trajectories to enhance operational efficiency.