This paper reports the approach to boost the acoustic performances of PMUTs (Piezoelectric Micromachined Ultrasonic Transducers) including vibrational amplitude, acoustic pressure and electromechanical coupling by using the pinning boundary structure. An analytical model is developed based on an assumed mode shape and is validated with matching results from numerical simulations. Prototyped devices are fabricated and tested with a measured 2.5X improvement in displacement and 3.5X higher pressure output per volt at resonance as compared to those of PMUTs with clamped boundary. As a demonstration example, a PMUT-based ultrasonic tilt sensor is investigated with measured result using the receiving PMUT’s pressure amplitude for a tilting range of ±8 degrees and an error of ±0.7 degrees.
Keywords: Piezoelectric micromachined ultrasonic transducers, PMUT, pinned PMUT, PMUT tilt sensor