Table 1.

Conventional and microelectromechanical systems (MEMS) based acoustic transducers.

Characteristics	Conventional	CMUT	PMUT	Fiber Optical	Acoustic Sensor
Sensors	PZT or PVDF	Capacitive	Thin film AlN/PZT	Microring	Fabry–Pérot Cavity
Array	Yes	Yes	Yes	challenging	challenging
Footprint	Bulky	OD < 3 mm	OD < 3 mm	<1 mm	<1 mm
Sensitivity	Medium	Medium	Medium	ultrahigh	High