Temperature and Substrate Dependence of Piezoelectric Sensitivity for PVDF Films

The piezoelectric sensitivity, via both the direct and converse effects, for commercial polyvinylidene fluoride (PVDF) films is measured as a function of temperature and frequency, for two substrates, nylon and aluminum. The average effective sensitivity for the PVDF on nylon was 29 pm/V for both direct and converse effect, independent of frequency over 0.5 to 200 Hz. Direct effect sensitivity on aluminum substrate was about a factor of five greater. Analysis of effects of substrate's thermal and elastic constraint disclosed insufficient effect to account for the observed increase of sensitivity. Flexoelectric effects were considered as the cause. The direct and converse sensitivity increased at approximately 2% per degree Celsius over the frequency range 0.5 to 200 Hz.