An Electret-Augmented Low-Voltage MEMS Electrostatic Out-of-Plane Actuator for Acoustic Transducer Applications

Despite the development of energy-efficient devices in various applications, microelectromechanical system (MEMS) electrostatic actuators yet require high voltages to generate large displacements. In this respect, electrets exhibiting quasi-permanent electrical charges allow large fixed voltages to...

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Bibliographic Details
Published in:Micromachines (Basel) 2020-03, Vol.11 (3), p.267
Main Authors: Sano, Chikako, Ataka, Manabu, Hashiguchi, Gen, Toshiyoshi, Hiroshi
Format: Article
Language:English
Subjects:
acoustic transducers
electrets
low-voltage-driven
soi-mems
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Summary:Despite the development of energy-efficient devices in various applications, microelectromechanical system (MEMS) electrostatic actuators yet require high voltages to generate large displacements. In this respect, electrets exhibiting quasi-permanent electrical charges allow large fixed voltages to be integrated directly within electrode structures to reduce or eliminate the need of DC bias electronics. For verification, a biased electret layer was fabricated at the inner surface of a silicon on insulator (SOI) structure facing a 2 μm gap owing to the high compatibility of silicon micromachining and the potassium-ion-electret fabrication method. A electret-augmented actuator with an out-of-plane motion membrane reached a sound pressure level (SPL) of 50 dB maximum with AC input voltage of alone, indicating a potential for acoustic transducer usage such as microspeakers. Such devices with electret biasing require only the input signal voltage, thus contributing to reducing the overall power consumption of the device system.
ISSN:2072-666X
2072-666X
DOI:10.3390/mi11030267