An Enhanced-Differential PMUT for Ultra-Long Distance Measurement in Air

This paper describes an enhanced-differential piezoelectric micromachined ultrasonic transducer (pMUT) based on Aluminum Nitride (AlN), which realizes ultralong and high-accurate distance measuring. Seven pieces of differential pMUT units with the average sensitivity of 2.077 μm/5V are integrated into one device to transmit or receive ultrasonic signal simultaneously, improving the signal strength significantly. With the resonant frequency of 77.34 kHz, this pMUT has a 4 cm-100 cm working range base on Time-of-Flight (ToF) measurement principle in chip-to-chip experiment. The test results show that maximum measuring error is 4 mm.