Piezoelectricity in multi-air voids electrets

Multi-air voids space-charge electrets have been developed using two fluorethylenepropylene (Teflon-FEP) films. In this work, a new technique developed to assembler these films allows the control of the thickness and shapes of multi-air voids distributed on their surface. When an impulse voltage process charges these voids, it is possible to obtain samples with high piezoelectric coefficients. To explain this piezoelectric characteristic, a theoretical explanation based on the electret microphone mechanism is introduced. Measurements show the piezoelectric coefficients for different frequencies.