Piezoelectric coefficients measurement for PVDF films with pneumatic pressure rig in a sole cavity

Longitudinal piezoelectric coefficient d₃₃ is one of the most important parameters of PVDF films. A pneumatic pressure rig with a sole cavity was designed to measure piezoelectric coefficients of PVDF films by monitoring the charge variation induced by the pressurized gas. The PVDF film sample was placed in the cavity without any clamps; therefore the in-plane stress caused by friction was eliminated. Then the measurement procedure and calculation of d₃₃ was optimized. The measurement results of PVDF films agreed with the coefficients measured by laser interferometer method. Comparison results showed that piezoelectric bulk d₃₃ measurement with this method also had good agreement with laser interferometer method and quasi-static method. It was demonstrated that the pneumatic pressure rig with a sole cavity was a simpler and more accurate method for d₃₃ measurement of PVDF films.