DocumentCode :
3097543
Title :
CMOS-based Capacitive Micromachined Ultrasonic Transducers operating without external DC bias
Author :
Fang-Yu Lin ; Wei-Cheng Tian ; Pai-Chi Li
Author_Institution :
Grad. Inst. of Biomed. Electron., Nat. Taiwan Univ., Taipei, Taiwan
fYear :
2013
fDate :
21-25 July 2013
Firstpage :
1420
Lastpage :
1423
Abstract :
In this study, a high sensitivity CMOS-based Capacitive Micromachined Ultrasonic Transducer (CMUT) is developed. This CMUT device provides high performance for operations with and without DC bias. It is implemented based on the TSMC 0.35μm 2P4M CMOS-MEMS process. The hypothesis is that driven by a commercial pulser, charges were injected into charge traps in CMUT and they were temporarily stored providing an internal electric field comparable to that created by an external DC bias. Therefore, the external DC bias is not needed but high sensitivity can still be achieved. From measurements, the device can produce ultrasound with a center frequency of 7-8 MHz, a fractional bandwidth of 75-85%, a sensitivity of 2.9mV/kPa, and an acoustic filed of 760kPa. Moreover, an image of a coin was reconstructed to demonstrate its performance. Compared with previous CMOS-based CMUTs, our device has good sensitivity and a wide bandwidth. The zero-bias CMUT based on a commercial CMOS process was successfully demonstrated with several potential applications. Nonetheless, our hypothesis on the charge trapping was also tested with discrepancy that still needs further investigation.
Keywords :
CMOS integrated circuits; acoustic field; capacitive sensors; ultrasonic transducers; CMOS-MEMS process; CMOS-based capacitive micromachined ultrasonic transducers; CMUT device; DC bias; acoustic filed; frequency 7 MHz to 8 MHz; Acoustics; Bandwidth; Dielectrics; Equations; Performance evaluation; Sensitivity; Ultrasonic transducers; CMOS; CMUT; transducer; ultrasound; zero-bias;
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.2013.0360
Filename :
6725092
Link To Document :
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