Improvement of Sensitivity of MEMS Ultrasonic Sensor Using P(VDF/TrFE) Thin Films

Abstract

MEMS (microelectromechanical systems) ultrasonic sensors were fabricated using a polyvinylidene fluoride-trifluoroethylene (P(VDF/TrFE)) copolymer thin film on multilayered diaphragm structures. We developed a new diaphragm structure to improve the sensitivity through lowering the stiffness of the vibration part of the sensor compared to the conventional ones. The new sensor structure improved the sensitivity up to about 5 times compared to conventional the ones. Fabricated sensors with the new structure showed their sensitivity, resonant frequency and Q-value as -74 dB (1V/Pa = 0 dB), 89.2 kHz and 24, respectively.