A piezoelectric micromachined ultrasonic transducer with mechanical grooves

Abstract This paper presents a novel architecture for annular and circular electrode piezoelectric micromachined ultrasound transducers (AC-PMUTs) with mechanical grooves. The mechanical grooves reduce stress and increase the vibration area of the membrane, resulting in enhanced vibrational deformation amplitude, transmission sensitivity, mechanical coupling coefficient ( k t 2 ), quality factor ( Q ), and emission sound pressure level (SPL). Compared with conventional AC-PMUTs without mechanical grooves, the transmitting displacement sensitivity was measured as 419.4 NM V −1 , which increased by 128.73%; the mechanical coupling coefficient ( k t 2 ) was measured as 6.09%, which increased by 116.43%; and the quality factor ( Q ) was measured as 90.68, which is an increase of 241.3%. The mechanical grooves also increased the emission SPL of PMUT at the same operating frequency. In the range of 10 kHz–70 kHz, the emission SPL of the optimum AC-PMUT with mechanical grooves can be improved in the range of 2.8 dB–28.8 dB. In general, AC-PMUTs with mechanical grooves have great potential in various emission ultrasound applications, such as distance measurement and object detection.