Measurement of Sensitivity Distribution Map of a Ferroelectret Polymer Film

Electromechanical Film (EMFi) is an electroactive ferroelectret polymer film with a special cellular structure. Sensitivity distribution maps of EMFi sensors were measured in this paper. Seven EMFi sensors with evaporated gold electrodes, a size of 55 mm * 55 mm, were measured with a measurement grid spacing of 5 mm. The sensitivity is defined here as the charge generated by the EMFi sensor divided by the force applied to excite the sensor, and this is closely related to piezoelectric d33 coefficient. The sensitivity of EMFi was found to vary in different places of the sensors and between the measured sensors. This is presumably due to the relatively large gas voids and local corona breakdowns. The aximum and minimum sensitivities were found to vary around 30% from the measured average sensitivity value. A thermally stimulated current analysis confirmed the results obtained in the sensitivity distribution map measurements.