Piezoelectric MEMS for acoustic and ultrasonic applications

Microelectromechanical systems (MEMS) integrated with piezoelectric thin films such as lead zirconate titanate (PZT) and aluminum scandium nitride (AlScN) have played a major role in acoustic and ultrasonic applications. This paper introduces piezoelectric MEMS devices including piezoelectric microphones and piezoelectric micromachined ultrasonic transducers (PMUTs) along with their target applications at various working frequency ranges, such as dual-frequency piezoelectric MEMS microphones for wind tunnel testing, dual-frequency PMUTs for super harmonic imaging, and air-coupled PMUTs with significantly extended bandwidth for gas flow metering.