Effect of ITO poling thickness, temperature, and protective layer on piezoelectric PVDF films

Abstract

Polyvinylidene fluoride (PVDF) is a semi-crystalline polymer with four crystalline phases α-, β-, γ-, and δ-phase, where α-phase is non-polar phase and three others are polar phase. The β-phase is highly polar compared with γ- and δ-phase, making it suitable for various sensors, actuators, and energy-harvesting applications. Therefore, this research aimed to investigate the impact of the protective layer on the output voltage response of the PVDF sensor and develop a novel ITO (Indium Tin Oxide) poling thickness method under vacuum conditions. The PVDF film was fabricated using the uniaxial stretching, with a ratio of R = 5 at a temperature of 80 °C. A new thickness polarization method using ITO glass in a vacuum oven at various temperatures was also proposed. The influence of poling temperature in vacuum conditions was determined by investigating several critical piezoelectricity properties utilizing FTIR, XRD, DSC, SEM, AFM, and PFM. The PVDF film was used as a sensing element, configured in a sandwiched structure to accurately measure impact forces. In addition, the performance of the PVDF sensor was assessed based on its output voltage, input/output sensitivity, and frequency responsiveness. Furthermore, the flexibility of the protective layer is not considered a performance measurement but is instead seen as a crucial aspect that affects the sensor's functionality. The sensor's ability to reliably detect and measure impact forces is greatly influenced by this factor, resulting in optimal performance at higher poling temperatures.