Invited
Large-scale fabrication of flexible piezoelectric PVDF films for engineering applications

Flexible polymers, such as Polyvinylidene fluoride (PVDF) comprise an exciting technological development and have attracted a lot of attention for their biocompatibility and high flexibility in the fabrication of piezoelectric sensors, actuators, and self-powering wearable devices. However, the lower piezoelectric properties of flexible polymers, compared to rigid ceramics, and the lack of large-scale fabrication processes are still halting the full commercialization of such flexible devices. We present a method to increase the piezoelectric properties of PVDF by adding nano fillers into the polymer matrix. In addition, we propose a novel method for large-scale fabrication of flexible piezoelectric film by means of a nozzle-less ultrasonic spray coating (USC). By using appropriate spraying properties, we can obtain highly uniform films with large piezoelectric coefficient d₃₃ and good crystallinity without the need of common post-processing, such as mechanical or electrical poling. The fabricated flexible piezoelectric films have been implemented throughout several engineering applications, such as touching sensors, wearable systems and health monitoring devices.