Professor David Horsley (University of California Davis) visited us at IIS and gave a talk on MEMS ultrasonic transducers along with an impressive demonstration of virtual-reality game with a PMUT stick.
Dr. Horsley gave an overview of the R&D history of ultrasonic transducers in past 20 years (or more) and discussed a use of piezoelectric AlN film for highly sensitive acoustic sensor / emitter. Applications includes finger-print reader, remote controller for tablet, and virtual reality computer game.