[BNC-all] FW: "Acoustic excitation of MEMS - seminar, 3.30 PM, Tue, July 17, BRK 1001"

[Lane, Melissa J]

"Noncontact Modal Excitation of Small Structures Using Ultrasound
Radiation Force"

 

July 17, 2007

3:30-4:30 PM

BRK 1001

 

Dr. Thomas M. Huber

Gustavus Adolphus College, Department of Physics

 

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 will describe a method that utilizes the radiation force at the
difference frequency generated by two intersecting ultrasound beams. The
resulting low-frequency excitations were measured using a scanning
vibrometer. This excitation technique has been demonstrated for hard
drive suspensions, MEMS and other small devices. There are several
unique advantages of the ultrasound radiation force relative to
mechanical shakers. The technique is relatively insensitive to
distracting resonances of fixtures and support structures. Another
advantage is broadband excitation; a 550-kHz confocal ultrasound
transducer can be used to excite resonance frequencies from 100 Hz to at
least 50 kHz. Other advantages include the ability to selectively excite
different modes. For example, the amplitude of a hard drive suspension's
5.0-kHz torsional mode was suppressed by an order of magnitude by
shifting the modulation phase between the two ultrasound beams by 90
degrees. Similarly, 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.

 

Short Bio:

Bachelors in Physics and Computer Science, St. John's University, 

Collegeville, MN, 1983

Ph.D. in Physics, University of Wyoming, 1989.

 

Thesis topic: Search for Mixing of Muonium and Antimuonium at the TRIUMF


accelerator in Vancouver, British Columbia

 

Current: Physics Department at Gustavus Adolphus College since 1989.

Current Research areas: Musical acoustics and ultrasound excitation.

 

 

 

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