A Proposal of New Multifunctional Pressure Sensor Based on PVDF Films

In this paper, a new multifunctional pressure sensor based on polyvinylidene difluoride (PVDF) films is proposed. The proposed sensor consists of a pair of PVDF films with urethane gel. The electrical voltage (capacitance) and ultrasonic propagation time are simultaneously measured by a pair of PVDF films. In addition, the voltages generated on the PVDF film by the vibration and temperature change are also measured due to the piezoelectric and pyroelectric effects. When the object is loaded onto the proposed sensor, the pressure is measured by the change of propagation time because the thickness of the urethane gel changes. In addition, information about the object, such as the electrical properties and vibration and temperature change, is obtained by the measured capacitance and voltages. Therefore, it is possible to measure the pressure, the electrical property, temperature change, and vibration of the object with the proposed sensor. In this experiment, the fundamental properties of the proposed sensor-pressure (weight), electrical property, vibration, and temperature-were presented. As results, electrical voltage and propagation time were measured with the relative standard deviations (RSDs) of the 21% and 2% between 0 and 50 kg weights. Two types of vibrations-sinusoidal wave of 1 Hz and pulse wave of 1.2 Hz-were detected with the RSDs of 2% and 1%, respectively. In addition, the peak voltage generated by temperature change between 14°C and 40°C was approximately measured with the RSD of 26%.