MEMS direction finding acoustic sensor
Authors
Karunasiri, Gamani
Alves, Fabio
Swan, William
Subjects
sound
sensor
MEMS
directional
Bio-inspired
sensor
MEMS
directional
Bio-inspired
Advisors
Date of Issue
2017-06-02
Date
Publisher
SPIE
Language
Abstract
Conventional directional sound sensing systems employ an array of spatially separated microphones to achieve directivity. However, there are insects such as the Ormia ochracea fly that can determine the direction of sound using a miniature hearing organ much smaller than the wavelength of sound it detects. The fly’s eardrums are coupled mechanically with a separation of only 0.5 mm and yet have a remarkable sensitivity to the direction of sound. The MEMS based sensor mimicking the fly’s hearing system was fabricated using an SOI substrate with a 25 μm device layer. The sensor consists of two 1.5 mm x1.6 mm wings connected in the middle by a 2.7 mm x 30 μm bridge. The entire structure is connected to the substrate by two torsional legs at the center. The frequency response of the sensor showed two resonance frequencies at approximately 1.1 kHz (rocking) and 1.5 kHz (bending). The resonance at 1.1 kHz is due to rocking of the wings by twisting the legs and the other at 1.5 kHz is due to bending of the bridge. The response of the sensor was probed electronically using comb finger capacitors integrated to the edges of the wings and with the help of an MS3110 chip. A peak output voltage of about 9V/Pa was measured for sound incident normal to the device at the resonance frequency of the bending mode. The bearing of the incident sound under these conditions could be determined to within a few degrees. These findings indicate the potential use of the MEMS sensor to locate sound sources with high accuracy.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.1117/12.2264952
Series/Report No
Department
Physics
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
CRUSER
NRP
ONR
NRP
ONR
Funder
Format
7 p.
Citation
Karunasiri, Gamani, Fabio Alves, and William Swan. "MEMS direction finding acoustic sensor." Smart Sensors, Actuators, and MEMS VIII. Vol. 10246. International Society for Optics and Photonics, 2017.
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.