Electromechanical response of cellular electret films

Charged films with a cellular structure show pseudo-piezoelectric properties with high transducer constants. The electromechanical response equations of such films are derived for their operation as sensors and actuators. Measurements of the direct and inverse transducer constants, the thermal stability of the charge, and Young's modulus are presented. By assuming reasonable charge distributions and charge densities, the calculated transducer constants are in good agreement with the measured values. Both the theoretical model and the measurements show the reciprocity of the transducer constants.