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Journal of Sensors
Volume 2016 (2016), Article ID 5298197, 8 pages
Research Article

A Two-Dimensional CMUT Linear Array for Underwater Applications: Directivity Analysis and Design Optimization

State Key Laboratory of Precision Measurement Technology and Instrument, Tianjin University, Tianjin 300072, China

Received 12 February 2016; Accepted 24 March 2016

Academic Editor: Rui Tang

Copyright © 2016 Wen Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Capacitive micromachined ultrasonic transducers (CMUTs) are one of the promising MEMS devices. This paper proposed an integrated vibration membrane structure to design a two-dimensional CMUT linear array for underwater applications. The operation frequencies for different medium have been calculated and simulated, which are 2.5 MHz in air and 0.7 MHz in water. The directivity analyses for the CMUT cell, subarray, and linear array have been provided. According to the product theorems, the directivity function of the complex array is obtained using a combination of the directivity functions of certain simple structures. Results show that the directivity of a CMUT cell is weak due to the small size, but the directivity of the designed linear array is very strong. Influential parameters of the linear array have been discussed, including the cell numbers, the adjacent distance, and the operation medium. In order to further suppress the side lobe interference and improve the resolution and the imaging quality of the imaging system, several weighting methods are used for optimization and comparison. Satisfactory side lobe suppression results are obtained, which can meet the actual requirements.