Highly Sensitive PVDF/CNTs/ZnO Flexible Piezoelectric Sensor for Detecting Human Subtle Motion

Flexible piezoelectric sensors have advantages of being ultra-thin, low modulus, lightweight, and flexible, which hold critical potential applications in health monitoring and human-machine interaction. However, the sensitivity and piezoelectric properties of flexible piezoelectric sensors still face challenges. Herein, we prepared a flexible polyvinylidene fluoride/carbon nanotubes/zinc oxide (PVDF/CNTs/ZnO) piezoelectric sensor that has an empathetic and good piezoelectric performance by electrospinning. To address the potential incompatibility between PVDF and ZnO at the interface and the uneven distribution of ZnO nanoparticles, CNTs were introduced as a "bridge" to connect ZnO with PVDF and achieved an effective combination between them. The output voltage of the PVDF/CNTs/ZnO piezoelectric sensor reached 0.1 V under a pressure of 4.1 N when ZnO loading was 3.0%, which was 6.67 times higher than that of pure PVDF nanofiber membrane. Moreover, the optimized piezoelectric device has a high sensitivity of up to 25.64 mV/N, which increased by 525% compared to pure PVDF piezoelectric devices. The device’s response and recovery times are 51 ms and 115 ms, respectively. The piezoelectric device can accurately monitor various human activities, including mouse clicks, pulse beats, wrist movements, and facial expressions, without needing an external power supply, demonstrating promising applications in human health monitoring.