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Proceedings Paper

Wideband micromachined acoustic sensors with radio frequency detection
Author(s): Sean T. Hansen; Arif Sanli Ergun; Butrus T. Khuri-Yakub
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Paper Abstract

Silicon micromachining techniques permit batch fabrication of microphones that are small, reproducible, and inexpensive. However, many such sensors have limited bandwidth or are too fragile to be used in a humid, wet, or dusty outdoor environment. Microphones using capacitive micromachined ultrasonic transducer (CMUT) membranes and radio frequency (RF) detection overcome some of the problems associated with conventional micromachined microphones. CMUT membranes can be vacuum-sealed and still withstand atmospheric pressure and submersion in water. In addition, the membrane mechanical response is very flat from dc up to hundreds of kilohertz. A very sensitive RF detection scheme is necessary to detect the small changes in membrane displacement that result from utilizing smaller membranes. In this paper, we present the theory and recent experimental results of RF detection with CMUT membranes. Measurements of a sensor with 1-mm2 area demonstrate a flat output response of the acoustic sensor from a fraction of 1 Hz to over 100 kHz, with a sensitivity at 1 kHz of 65 dB/Pa in a 1-Hz noise bandwidth.

Paper Details

Date Published: 18 September 2003
PDF: 9 pages
Proc. SPIE 5090, Unattended Ground Sensor Technologies and Applications V, (18 September 2003); doi: 10.1117/12.498272
Show Author Affiliations
Sean T. Hansen, Stanford Univ. (United States)
Arif Sanli Ergun, Stanford Univ. (United States)
Butrus T. Khuri-Yakub, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 5090:
Unattended Ground Sensor Technologies and Applications V
Edward M. Carapezza, Editor(s)

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