Prepolarized Electroacoustic and Vibrational Sensors

New developments in the field of prepolarized capacitive sensors for sound and vibration are discussed. The sensors are either based on electrets or on piezoelectrets, the latter are also called ferroelectrets [1,2]. With such materials, novel microphones, ultrasonic transducers, accelerometers and vibration-based energy harvesters have been implemented. A few of these transducers will be described in this paper.