Wideband micromachined acoustic sensors with radio frequency detection

Sean T. Hansen; Arif Sanli Ergun; Butrus T. Khuri-Yakub

doi:10.1117/12.498272

18 September 2003 Wideband micromachined acoustic sensors with radio frequency detection

Sean T. Hansen, Arif Sanli Ergun, Butrus T. Khuri-Yakub

Proceedings Volume 5090, Unattended Ground Sensor Technologies and Applications V; (2003) https://doi.org/10.1117/12.498272
Event: AeroSense 2003, 2003, Orlando, Florida, United States

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.

Citation Download Citation

Sean T. Hansen, Arif Sanli Ergun, and Butrus T. Khuri-Yakub "Wideband micromachined acoustic sensors with radio frequency detection", Proc. SPIE 5090, Unattended Ground Sensor Technologies and Applications V, (18 September 2003); https://doi.org/10.1117/12.498272

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