Noncontact modal excitation of small structures using ultrasound radiation force

Thomas M. Huber, Scott D. Hagemeyer, Eric T. Ofstad, Mostafa Fatemi, Randall R. Kinnick, James F. Greenleaf

Research output: Chapter in Book/Report/Conference proceedingConference contribution

10 Scopus citations

Abstract

Modal analysis of MEMS and other small structures is important for many applications. However, conventional excitation techniques normally require contact, which may not be feasible for small objects. We present a non-contact method that uses interference of ultrasound frequencies in air to produce low-frequency excitation of structures. Objects studied included a MEMS mirror, MEMS gyroscope, hard drive suspensions, and a brass cantilever. The vibration induced by the ultrasound radiation force was varied in a wide range from 0 Hz to over 50 kHz. Object motion was detected using a laser vibrometer; measured frequencies agreed with expected values. Also demonstrated was the unique capability to selectively enhance or suppress modes independently. For example, for a MEMS mirror, the relative amplitude of a torsional mode could be enhanced by a factor of 10 by changing the ultrasound focus spot position. Similarly, the ratio of the vibrational amplitudes of the torsional modes of a MEMS mirror around two axes could be changed from in excess of 20:1 to less than 1:2 by shifting the ultrasound modulation phase 90 degrees.

Original languageEnglish (US)
Title of host publicationProceedings of the SEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007
Pages604-610
Number of pages7
StatePublished - Nov 19 2007
EventSEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007 - Springfield, MA, United States
Duration: Jun 3 2007Jun 6 2007

Publication series

NameProceedings of the SEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007
Volume1

Other

OtherSEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007
CountryUnited States
CitySpringfield, MA
Period6/3/076/6/07

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ASJC Scopus subject areas

  • Mechanical Engineering

Cite this

Huber, T. M., Hagemeyer, S. D., Ofstad, E. T., Fatemi, M., Kinnick, R. R., & Greenleaf, J. F. (2007). Noncontact modal excitation of small structures using ultrasound radiation force. In Proceedings of the SEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007 (pp. 604-610). (Proceedings of the SEM Annual Conference and Exposition on Experimental and Applied Mechanics 2007; Vol. 1).