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Proceedings Paper

Electrostatic comb drive for vertical actuation
Author(s): Abraham P. Lee; Charles F. McConaghy; Peter A. Krulevitch; Eugene Warren Campbell; Gary E. Sommargren; Jimmy C. Trevino
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Paper Abstract

The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 micrometers gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 micrometers above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental result, and a general design guideline is derived from these result. The suspension flexure stiffness, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.

Paper Details

Date Published: 5 September 1997
PDF: 11 pages
Proc. SPIE 3224, Micromachined Devices and Components III, (5 September 1997); doi: 10.1117/12.284506
Show Author Affiliations
Abraham P. Lee, Lawrence Livermore National Lab. (United States)
Charles F. McConaghy, Lawrence Livermore National Lab. (United States)
Peter A. Krulevitch, Lawrence Livermore National Lab. (United States)
Eugene Warren Campbell, Lawrence Livermore National Lab. (United States)
Gary E. Sommargren, Lawrence Livermore National Lab. (United States)
Jimmy C. Trevino, Lawrence Livermore National Lab. (United States)


Published in SPIE Proceedings Vol. 3224:
Micromachined Devices and Components III
Kevin H. Chau; Patrick J. French, Editor(s)

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