DocumentCode :
3094131
Title :
Air-coupled CMUTs operating at ambient pressures ranging from 1 to 20 atm
Author :
Min-Chieh Ho ; Kwan Kyu Park ; Eckhoff, Kristian ; Kupnik, Mario ; Khuri-Yakub, Butrus T.
Author_Institution :
Stanford Univ., Stanford, CA, USA
fYear :
2013
fDate :
21-25 July 2013
Firstpage :
1412
Lastpage :
1415
Abstract :
We present impedance and pitch-catch measurements of capacitive micromachined ultrasonic transducers (CMUTs) in permanent contact mode with improved mechanical strength that demonstrate functionality up to 20 atm ambient pressure. Changes in device design and fabrication are made to improve the mechanical strength of the CMUT plates, including using smaller deflection to thickness ratio (9 - 33%), choosing better quality SOI wafers (bowing <; 20 μm), and designing a much larger bonding area (300 - 700 μm overlap in radial direction) for each cell. As a result, all designs with 2000 μm radius, 65-μm-thick plates, 7.74 μm gap heights and with 300, 500, and 700 μm wide bonding area overlap for the plate, performed from 1 - 20 atm without a single failure. Despite larger bonding area, pitch-catch measurements with these CMUTs (700 μm bonding width biased at 250 V dc) still give received signal with good SNR even at 20 atm. Our results support that such CMUTs are reliable and efficient over a wide pressure range.
Keywords :
acoustic impedance; acoustic noise; acoustic signal processing; capacitive sensors; ultrasonic transducers; CMUT plates; SOI wafers; capacitive micromachined ultrasonic transducers; impedance measurements; mechanical strength; pitch-catch measurements; pressure 1 atm to 20 atm; signal-noise ratio; Acoustics; Bonding; Frequency measurement; Impedance; Impedance measurement; Pressure measurement; CMUT; FEA; electrical impedance; permanent contact mode; pitch-catch; wide pressure range;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium (IUS), 2013 IEEE International
Conference_Location :
Prague
ISSN :
1948-5719
Print_ISBN :
978-1-4673-5684-8
Type :
conf
DOI :
10.1109/ULTSYM.2013.0358
Filename :
6724920
Link To Document :
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