Electrostatic comb drive for vertical actuation

Abraham P. Lee; Charles F. McConaghy; Peter A. Krulevitch; Eugene Warren Campbell; Gary E. Sommargren; Jimmy C. Trevino

doi:10.1117/12.284506

5 September 1997 Electrostatic comb drive for vertical actuation

Abraham P. Lee, Charles F. McConaghy, Peter A. Krulevitch, Eugene Warren Campbell, Gary E. Sommargren, Jimmy C. Trevino

Proceedings Volume 3224, Micromachined Devices and Components III; (1997) https://doi.org/10.1117/12.284506
Event: Micromachining and Microfabrication, 1997, Austin, TX, United States

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.

Citation Download Citation

Abraham P. Lee, Charles F. McConaghy, Peter A. Krulevitch, Eugene Warren Campbell, Gary E. Sommargren, and Jimmy C. Trevino "Electrostatic comb drive for vertical actuation", Proc. SPIE 3224, Micromachined Devices and Components III, (5 September 1997); https://doi.org/10.1117/12.284506

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