Nanofibrous PVDF-Based Smart Flexible Fabrics with High Piezoelectric Properties for Human Motion Monitoring

Abstract

Flexible piezoelectric sensors have received extensive attention for wearable real-time human motion monitoring applications due to their self-powered capacity, wearability, and lightweight properties. However, developing piezoelectric sensors with both high sensitivity and substantial voltage outputs remains challenging. This study presents an innovative yet straightforward approach to fabricate high-performance piezoelectric flexible textiles by stretching electrospun oriented PVDF nanofiber (SO-PVDF). The macroscopic alignment of the PVDF nanofiber prevents fiber flipping and sliding during stretching, enabling efficient transfer of mechanical strain to molecular chains. This results in a remarkable improved relative content of β crystal of 95.1%, representing high piezoelectric performance. The resulting PVDF yarn shows good mechanical strength, overcoming the typical fragility limitations of electrospun materials. The assembled piezoelectric generators (SO-PEG) show high piezoelectric performance, including substantial voltage outputs (27 V), high sensitivity (0.93 V/N), rapid response time (T_r = 93 ms, T_f = 84 ms), and good operational stability (>2000 cycles). Furthermore, the SO-PEG serves as a versatile self-powered sensor capable of detecting both small movement (finger bending) and large-scale movements (elbow, knee, and foot movement) based on efficient mechanical-to-electrical energy conversion. Overall, this work provides a cost-effective and scalable strategy for manufacturing high-performance wearable piezoelectric sensors, opening possibilities for intelligent biomonitoring applications.