Radiation impedance of collapsed capacitive micromachined ultrasonic transducers

Date
2012
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Print ISSN
0885-3010
Electronic ISSN
Publisher
Institute of Electrical and Electronics Engineers
Volume
59
Issue
6
Pages
1301 - 1308
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Series
Abstract

The radiation impedance of a capacitive micromachined ultrasonic transducer (CMUT) array is a critical parameter to achieve high performance. In this paper, we present a calculation of the radiation impedance of collapsed, clamped, circular CMUTs both analytically and using finite element method (FEM) simulations. First, we model the radiation impedance of a single collapsed CMUT cell analytically by expressing its velocity profile as a linear combination of special functions for which the generated pressures are known. For an array of collapsed CMUT cells, the mutual impedance between the cells is also taken into account. The radiation impedances for arrays of 7, 19, 37, and 61 circular collapsed CMUT cells for different contact radii are calculated both analytically and by FEM simulations. The radiation resistance of an array reaches a plateau and maintains this level for a wide frequency range. The variation of radiation reactance with respect to frequency indicates an inductance-like behavior in the same frequency range. We find that the peak radiation resistance value is reached at higher kd values in the collapsed case as compared with the uncollapsed case, where k is the wavenumber and d is the center-to-center distance between two neighboring CMUT cells.

Course
Other identifiers
Book Title
Keywords
Capacitive micromachined ultrasonic transducer, Contact radius, Critical parameter, FEM simulations, Finite element method simulation, Frequency ranges, Linear combinations, Mutual impedance, Radiation impedance, Radiation resistance, Special functions, Velocity profiles, Wave numbers, Wide frequency range, Cells, Cytology, Finite element method, Transducers, Ultrasonic transducers, Radiation
Citation
Published Version (Please cite this version)