Fabrication of MEMS Directional Acoustic Sensors for Underwater Operation
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Authors
Espinoza, Alberto
Alves, Fabio
Rabelo, Renato
Da Re, German
Karunasiri, Gamani
Subjects
MEMS
directional
underwater
sensor
directional
underwater
sensor
Advisors
Date of Issue
2020-02
Date
2020-02
Publisher
MDPI
Language
en_US
Abstract
In this work, microelectromechanical systems (MEMS)-based directional acoustic sensors operating in an underwater environment are explored. The studied sensors consist of a free-standing single wing or two wings pivoted to a substrate. The sensors operate in a narrow frequency band determined by the resonant frequency of the mechanical structure. The electronic readout of the mechanical response is obtained using interdigitated comb finger capacitors attached to the wings. The characteristics of MEMS sensors immersed in silicone oil are simulated using finite element modeling. The performance of the sensors is evaluated both in air and underwater. For underwater testing and operation, the sensors are packaged in a housing containing silicone oil, which was specially developed to present near unity acoustic transmission. The measurements show that the resonant frequency of the sensors obtained in air shifts to a lower frequency when immersed in silicone oil, which is primarily due to the mass loading of the liquid. The peak sensitivity of the MEMS sensors is approximately 6 mV/Pa or −165 dB re 1 V/μPa, and the directional response shows a dipole pattern. The signal-to-noise ratio was found to be about 200 or 23 dB at 1 Pa incident sound pressure. The results show the potential of MEMS sensors to be used in underwater applications for sound source localization.
Type
Article
Description
The article of record as published may be found at https://doi.org/10.3390/s20051245
Series/Report No
Department
Physics
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
11 p.
Citation
Espinoza, Alberto, et al. "Fabrication of MEMS Directional Acoustic Sensors for Underwater Operation." Sensors 20.5 (2020): 1245.
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.