The objective of this project was to characterize and model two designs of a capacitive micromachined ultrasonic transducer (cMUT) for medical ultrasound purposes.
As a relatively new MEMS technology, cMUTs have become a competitive alternative to the regularly used piezoelectric transducers in the medical diagnostic field. Due to several advantages that they hold over piezoelectric transducer materials, the research and development of cMUTs have increased greatly over the past couple of decades, and will continue to do so into the future.
The specific goals of this thesis were to provide a hybrid finite element/lumped element modeling scheme for cMUT elements and arrays, and to compare the predictions to laser Doppler velocimetry measurements.
Research began with developing an understanding of lumped element acoustic modeling, and from this, a lumped element acoustic model was created for the cMUT designs. Cross-sectional models for the different geometries of the cMUTs were created using COMSOL 3.3 Multiphysics, in order to determine the values for several of the lumped model’s elements. After creating a computational model through the use of Matlab, frequency plots were generated for the transducers in both air and water environments.
1. Cheng, X., et al. CMUT-in-CMOS ultrasonic transducer arrays with on-chip electronics. in International Conference on Solid-State Sensors, Actuators, & Microsystems. 2009.
2. Wikipedia. Ultrasound. [cited; General ultrasound information]. Available from: http://en.wikipedia.org/wiki/Ultrasound.
3. Eisenberg, R.L., Radiology: an illustrated history. 1992: Mosby Inc.
4. Van Tiggelen, R. and E. Pouders, Ultrasound and computed tomography: Spin offs of the world wars. JBR-BTR, 2003. 86(4): p. 235-241.
5. Woo, J., A short history of the development of ultrasound in obstetrics and gynecology. University of Oxford. Available: http://www.obultrasound. net/history1.html, Accessed July, 1998. 6: p. 2005.
6. Pallardy, G., M.J. Pallardy, and A. Wackenheim, Histoire illustrée de la radiologie. 1989: R. Dacosta.
7. Library, S.a.S.P. Galton’s whistle, c 1900. 2004 [cited; An explanation of the workings of Galton’s whistle]. Available from: http://www.scienceandsociety.co.uk/results.asp?image=10317352.
8. Piezo Systems, I. History of Piezoelectricity. [cited; A history of piezoelectricity and piezoelectric materials]. Available from: http://www.piezo.com/tech4history.html.
9. Wade, G., Human uses of ultrasound: ancient and modern. Ultrasonics, 2000. 38(1-8): p. 1-5.
10. Gohe, H. and T. Wedekind, Der ultraschall in der medizin. Journal of Molecular Medicine, 1940. 19(2): p. 25-29.
11. Payne, P.A., Medical and industrial applications of high resolution ultrasound. Journal of Physics E: Scientific Instruments, 1985. 18: p. 465-473.
12. Instruments, N. Fundamental of Ultrasonic Imaging and Flaw Detection. [cited; Image of ultrasound flaw detection]. Available from: http://zone.ni.com/devzone/cda/tut/p/id/3368.
13. Shoh, A., Industrial Applications of Ultrasound-A Review I. High-Power Ultrasound. IEEE transactions on sonics and ultrasonics, 1975. 22(2): p. 60-70.
14. Leighton, T.G., What is ultrasound? Progress in biophysics and molecular biology, 2007. 93(1-3): p. 3-83.
15. Freudenrich, C.C., How Ultrasound Works. Visited October, 2006. 26.
16. On, T. [cited; Image of ultrasound system]. Available from: http://techon.nikkeibp.co.jp/article/NEWS/20070410/130485/?SS=imgview&FD=-857567563.
17. Khuri-Yakub, B.P.T., et al., Micromachined transducers enable real-time three dimensional imaging.
18. Wikipedia. Piezoelectricity. [cited; Definition of the piezoelectric effect]. Available from: http://en.wikipedia.org/wiki/Piezoelectricity.
19. Inc., B.P.-O. An Introduction to Piezoelectric Transducer Crystals. [cited; Images of the Piezoelectric effect]. Available from: http://www.bostonpiezooptics.com/?D=6.