d33 mode piezoelectric diaphragm based acoustic transducer with high sensitivity

This paper presents the design, fabrication, and characterization of an acoustic transducer using a piezoelectric freestanding bulk diaphragm as the sensing element. The diaphragm bearing the spiral electrode operates in d33 mode, which allows the in-plane deformation of the diaphragm to be converted to the out-of-plane deformation and generates an acoustic wave in the same direction. A finite element code is developed to reorient the material polarization distribution according to the poling field calculated. The first four resonance modes have been simulated and verified by impedance and velocity spectra. The sensitivity and the sound pressure level of the transducer were characterized. The realized sensitivity of 126.21 μV/Pa at 1 kHz is nearly twenty times of the sensitivity of a sandwich d31 mode transducer.

► A piezoelectric freestanding diaphragm based acoustic transducer has been fabricated. ► The diaphragm bearing the spiral electrode operates in d33 mode. ► A program reorients the polarization distribution according to the poling field. ► The sensitivity and sound pressure level of a single element have been measured. ► The d33 mode diaphragm shows higher sensitivity than the d31 mode diaphragm.