Title:Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-frequency Underwater Imaging
VOLUME: 14 ISSUE: 2
Author(s):Yuanyu Yu, Jiujiang Wang*, Xin Liu, Sio H. Pun, Weibao Qiu, Shuang Zhang, Ching H. Cheng, Kin F. Lei, Mang I. Vai and Peng U. Mak
Affiliation:Data Recovery Key Laboratory of Sichuan Province, College of Computer Science and AI, Neijiang Normal University, Neijiang 641100, Data Recovery Key Laboratory of Sichuan Province, College of Computer Science and AI, Neijiang Normal University, Neijiang 641100, State Key Laboratory of Analog and Mixed-Signal VLSI, University of Macau, Macau 999078, State Key Laboratory of Analog and Mixed-Signal VLSI, University of Macau, Macau 999078, Shenzhen Key Laboratory of Ultrasound Imaging and Therapy Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Data Recovery Key Laboratory of Sichuan Province, College of Computer Science and AI, Neijiang Normal University, Neijiang 641100, School of Automotive Engineering, Wuhan University of Technology, Wuhan 430070, Graduate Institute of Biomedical Engineering, Chang Gung University, Taoyuan 33302, State Key Laboratory of Analog and Mixed-Signal VLSI, University of Macau, Macau 999078, Faculty of Science and Technology, Department of Electrical and Computer Engineering, University of Macau, Macau 999078
Keywords:Capacitive micromachined ultrasonic transducer, underwater imaging, sacrificial release process, Zirconate Titanate,
device design, Capacitive micromachined ultrasonic transducer (CMUT).
Abstract:Background: Ultrasound is widely used in the applications of underwater imaging. Capacitive
micromachined ultrasonic transducer (CMUT) is a promising candidate for the traditional
piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be
achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound
imaging is proposed in this work.
Methods: Analytical methods were used to calculate the center frequency in water and the pull-in
voltage for determining the operating point of CMUT. A finite element method model was developed
to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial
release process.
Results: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional
bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment
was carried out with the target of three steel wires.
Conclusion: In this study, we have developed CMUT for high-frequency underwater imaging.
The experiment showed that the CMUT could detect the steel wires with a diameter of 100 μm
and the axial resolution was 0.582 mm, which was close to one wavelength of ultrasound in
2.6 MHz.
