Enhanced performance of flexible Piezoelectric PVDF sensors by ultrasonic spray coating method

Polyvinylidene fluoride (PVDF) has been attracting a lot of interest among researchers for the fabrication of biocompatible flexible piezoelectric sensors. However, low piezoelectric properties and lack of a simple large-scale fabrication method has prevented commercialization of such sensors. In this research, a nozzle-less ultrasonic spray coating (USC) method is introduced and used for the development of pure PVDF sensors with high performance and sensitivity. PVDF films with thickness of ~9 μm are fabricated by USC, and their morphology, crystalline structure, piezoelectric properties, and sensing performance are studied and compared to sensors made by casting method. The obtained piezoelectric coefficients of the USC fabricated sensors (d33=38 pm/V) are higher than PVDF sensors available in the literature fabricated by other common methods. By applying various testing forces at controlled low frequencies, the output voltage, linearity, and sensitivity of the sensor is found to be higher than the similar sensor made by drop casting method. Therefore, this study presents a simple and cheap process for large-scale fabrication of high-efficiency biocompatible sensors.