Resonances and nonuniformities in CMUT elements or arrays

Date
2014-09
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Source Title
2014 IEEE International Ultrasonics Symposium, IUS
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Publisher
IEEE
Volume
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Pages
297 - 300
Language
English
Type
Conference Paper
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Abstract

We determine the response of individual cells of a CMUT array immersed in water using the small-signal equivalent circuit of a single cell and radiation impedances. Using a numerically efficient technique, we are able to simulate large arrays. The results indicate the presence of resonances at low frequencies where Rayleigh-Bloch waves are excited on the surface of the array. Reflections from the edges cause standing-wave patterns. Above the cut-off frequency of Rayleigh-Bloch waves, no standing-wave pattern exists. However, there is nonuniformity among cell velocities mainly due to unequal radiation impedance seen by the cells. Rayleigh-Bloch waves and nonuniformity in cell velocities do not cause a significant degradation in the point spread function, but the oscillations extend the duration of impulse response, limiting the dynamic range. © 2014 IEEE.

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Keywords
Cells, Elastic waves, Heterojunction bipolar transistors, Impulse response, Optical transfer function, Dynamic range, Individual cells, Large arrays, Non-uniformities, Nonuniformity, Radiation impedance, Small signal equivalent circuit, Standing wave patterns, Cytology
Citation
Published Version (Please cite this version)