Characterization of Nanoscale Ultrasonic Transducer Elements as Effective Acoustical Devices

Abstract:

The generation and detection of ultrasound in air has many applications in the field of ranging, non-destructive evaluation, microscopy and the most impactful in medical imaging. Conventional designs of electrostatic transducers have large electrode spacing of 50-100 μm which reduces the sensitivity of these capacitors. In the last one and a half decade silicon micromachining is used to define capacitors with gap spacing as small as 500Å, making it possible highly efficient capacitive micromachined ultrasonic transducers (CMUTs). In this paper a CMUT element is analytically characterized and FEM simulated. The observations are compared with published experimental results and excellent agreement is found between them.

• Periodical: Applied Mechanics and Materials (Volume 860)
• Pages: 35-40
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.860.35
• Online since: December 2016
• Authors: Reshmi Maity*, Niladri Pratap Maity, R.K. Thapa, S. Baishya
• Keywords: CMUT, MEMS, PZFLEX, Ultrasonic Transducer

References

[1] D. Schindel, D. Hutchins, Applications of Micromachined Capacitance Transducers in Air Coupled Ultrasonics and Nondestructive Evaluation, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 42 (1995) 51-58.

DOI: 10.1109/58.368313

[2] I. Ladabaum, B. T. Khuri-Yakub, Micromachined Ultrasonic Transducer: 11. 4 MHz Transmission in Air and more, Applied Physics Letter 68 (1996) 7-9.

DOI: 10.1063/1.116764

[3] O. Oralkan, A. Ergun, C. Cheng, J. Johnson, M. Karaman, T. Lee, B. T. Khuri-Yakub, Volumetric Ultrasound Imaging Using 2-D CMUT Arrays, lEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 50 (2003) 1581-1594.

DOI: 10.1109/tuffc.2003.1251142

[4] A. Ergun, Y. Huang, X. Zhuang, ¨O. Oralkan, G. Yaralıoglu, B. T. Khuri-Yakub, Capacitive Micromachined Ultrasonic Transducers: Fabrication Technology, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 52 (2005) 2242-2258.

DOI: 10.1109/tuffc.2005.1563267

[5] A. Cetin, B. Bayram, Diamond-Based Capacitive Micromachined Ultrasonic Transducers in Immersion, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 60 (2013) 414-420.

DOI: 10.1109/tuffc.2013.2578

[6] M. Rahman, J. Hernandez, S. Chowdhury, An Improved Analytical Method to Design CMUTs with Square Diaphragms, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 60 (2013) 834-845.

DOI: 10.1109/tuffc.2013.2632

[7] A. Logan, L. Wong, J. Yeow, A 1-D Capacitive Micromachined Ultrasonic Transducer Imaging Array Fabricated With a Silicon-Nitride-Based Fusion Process, IEEE/ASME Transactions on Mechatronics 16 (2011) 861-865.

DOI: 10.1109/tmech.2011.2159732

[8] H. Oğuz, A. Atalar, H. Koymen, Equivalent Circuit-Based Analysis of CMUT Cell Dynamics in Arrays, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 60 (2001) 1016-1024.

DOI: 10.1109/tuffc.2013.2660

[9] O. Oralkan, X. Jin, F. Degertekin, B. T. Khuri-Yakub, Simulation and Experimental Characterization of a 2-D Capacitive Micromachined Ultrasonic Transducer Array Element, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 46 (1999).

DOI: 10.1109/58.808855

[10] Y. Tsuji, M. Kupnik, B. T. Khuri-Yakub, Low Temperature Process for CMUT Fabrication with Wafer Bonding Technique, Proc. IEEE Ultrasonics Symposium (2010) 551-554.

DOI: 10.1109/ultsym.2010.5935632

[11] M. Haller, B. T. Khuri-Yakub, A Surface Micromachined Electrostatic Ultrasonic Air Transducer, Proc. IEEE Ultrasonics Symposium (1994) 1241-1244.

DOI: 10.1109/ultsym.1994.401810

[12] M. Anderson, J. Hill, C. Fortunko, N. Dogan, R. Moore, Broadband electrostatic transducers: Modeling and experiments, J. Acoust. Soc. of America 97 (1995) 262-272.

DOI: 10.1121/1.412310

[13] Reshmi Maity, R. K. Thapa, S. Baishya, Membrane Displacement Behavior of Capacitive Micromachined Ultrasonic Transducers under Static Bias, Advanced Materials Research 816 (2013) 892-896.

DOI: 10.4028/www.scientific.net/amr.816-817.892

[14] Reshmi Maity, N. P. Maity, R. K. Thapa, S. Baishya, Analysis of Frequency Response Behaviour of Capacitive Micromachined Ultrasonic Transducers, Journal of Computational and Theoratical Nanoscience 12 (2015), 3492-3494.

DOI: 10.1166/jctn.2015.4227

[15] Reshmi Maity, N. P. Maity, R. K. Thapa, S. Baishya, Analytical Characterization and Simulation of a 2-D Capacitive Micromachined Ultrasonic Transducer Array Element, Journal of Computational and Theoratical Nanoscience 12 (2015), 3692-3696.

DOI: 10.1166/jctn.2015.4261

[16] O. Ahrens, A. Buhrdorf, D. Hohlfeld, L. Tebje, J. Binder, Fabrication of Gap-Optimized CMUT, IEEE Trans on Ultrasonics, Ferroelectrics, and Frequency Control 49 (2002), 1321-1329.

DOI: 10.1109/tuffc.2002.1041549