Ultrasound technologies can be applied to a variety of applications, such as medical imaging/therapeutics, materials assessment, flow rate measurement and others. Piezoelectric micromachined ultrasonic transducers (PMUTs) have advantages over the traditional bulk transducers in wide bandwidth, small size, and low cost. This work proposes to boost PMUT’s acoustic performance further including vibrational amplitude, acoustic pressure and electromechanical coupling by using the pinning boundary structure and to explore various new applications. The equivalent circuit model for pinned boundary...