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Air-coupled capacitive micromachined ultrasonic transducer for temperature field reconstruction

Capacitive micromachined ultrasonic transducer (CMUT) is a kind of ultrasonic sensor based on Micro-electromechanical Systems (MEMS) process. CMUT has the advantages of low acoustic impedance, high sensitivity, high quality factor. In this paper, an air-coupled capacitive micromachined ultrasonic transducer is introduced. The operating frequency of the device is 221kHz at the DC biased voltage of 100V. Besides, the potential of the CMUT for temperature field image reconstruction based on acoustic tomography has been demonstrated by experiments. The area above the heating wire is scanned by a pair of CMUTs to obtain the ultrasonic transmission time of different acoustic paths, then the temperature field is reconstructed by the least square algorithm.