Analytic modeling of loss and cross-coupling in capacitive micromachined ultrasonic transducers

Date
1998
Authors
Bozkurt, A.
Degertekin, F. L.
Atalar, Abdullah
Khuri-Yakub, B. T.
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
Proceedings of the IEEE Ultrasonics Symposium
Print ISSN
1051-0117
Electronic ISSN
Publisher
IEEE, Piscataway, NJ, United States
Volume
2
Issue
Pages
1025 - 1028
Language
English
Type
Article
Journal Title
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Volume Title
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Abstract

The structural loss mechanism of capacitive micromachined ultrasonic transducer (cMUT) is investigated using finite element analysis and the normal mode theory. A single micromachined transducer membrane on an infinite silicon substrate is simulated by incorporating absorbing boundary conditions in the finite element method. This enables direct evaluation of the mechanical impedance of the membrane. Furthermore, the field distribution along the thickness of the silicon substrate due to outward radiating wave modes is obtained. The normal mode theory is applied to extract the contributions of different wave modes to the complicated field distributions. It is found that, the lowest order Lamb wave modes are responsible for the loss. Evaluation of absolute and relative power losses due to individual modes indicate that the lowest order anti-symmetric (A0) mode is the dominant radial mode in agreement with experimental measurements. The results of the analysis are used to derive a detailed equivalent circuit model of a cMUT with structural loss.

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Keywords
Boundary conditions, Capacitors, Computer simulation, Electric fields, Electric losses, Equivalent circuits, Finite element method, Mathematical models, Silicon sensors, Capacitive micromachined ultrasonic transducers (CMUT), Cross coupling, Ultrasonic transducers
Citation
Published Version (Please cite this version)