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Proceedings Paper

Simulation characterization of CMUT with vented square membrane
Author(s): Wen Zhang; Hui Zhang; Yuan Wang; Fei Du; Shijiu Jin; Zhoumo Zeng
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Paper Abstract

Being one of the appealing MEMS devices for both immersion and air-coupled applications, capacitive micromachined ultrasonic transducers (CMUTs) are often featuring vacuum/sealed cavities. However, the pressure differential across the membrane requires higher drive voltage to start the vibration. Besides, the air film formed in the narrow gap consequently being squeezed provides additional damping as well as stiffening for the membrane. Moreover, the fabrication technologies encounter difficulties in stress control and thin membrane releasing during the hermetical cavity formations. In this paper, we propose using surface micromaching technology to fabricate CMUTs with vented square membrane for air-coupled applications. In order to compare the performance of CMUTs with and without vented holes on the membrane using finite element analysis (FEA), we have developed several 3D finite element models using commercially available FEA software (COMSOL Multiphysics). According to the simulation results, our design remains the similar first resonant frequency and has higher frequency interval, indicating a better signal-to-noise rate (SNR). Eigenfrequency comparison between CMUTs with the same movable area implies that the presence of the vented holes lowers the first order frequency by around 5.7%. We have demonstrated that the idea of fabricating air-coupled CMUTs with vented holes on the square membrane is feasible and our proposal could stay around the designed resonant frequency. Further characterization will be done in the near future.

Paper Details

Date Published: 12 August 2015
PDF: 6 pages
Proc. SPIE 9624, 2015 International Conference on Optical Instruments and Technology: Micro/Nano Photonics and Fabrication, 962406 (12 August 2015); doi: 10.1117/12.2192802
Show Author Affiliations
Wen Zhang, Tianjin Univ. (China)
Hui Zhang, Tianjin Univ. (China)
Yuan Wang, Tianjin Univ. (China)
Fei Du, Tianjin Univ. (China)
Shijiu Jin, Tianjin Univ. (China)
Zhoumo Zeng, Tianjin Univ. (China)

Published in SPIE Proceedings Vol. 9624:
2015 International Conference on Optical Instruments and Technology: Micro/Nano Photonics and Fabrication
Zhiping Zhou; Changhe Zhou; Pavel Cheben, Editor(s)

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