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Article
Static friction and surface roughness studies of surface micromachined electrostatic micromotors using an atomic force/friction force microscope
Journal of Vacuum Science and Technology A (2001)
  • Sriram Sundararajan, The Ohio State University
  • Bharat Bhushan, The Ohio State University
Abstract

A technique to measure the static friction forces (stiction) encountered in surface micromachined micromotors using a commercial atomic force microscope (AFM)/friction force microscope has been developed and is described. An AFM tip is pushed against a rotor arm of the micromotor so as to generate lateral deflection (torsion) of the tip, which is measured by the AFM. The maximum value of the lateral deflection obtained prior to rotor movement (rotation) is a measure of the static friction force of the micromotors. This technique was employed to study the effect of humidity and rest time on the static friction force of polysilicon motors, both unlubricated and lubricated using perfluoropolyether lubricants. Surface roughness parameters (rms, peak-to-valley distance, skewness, and kurtosis) and microscale friction properties of the various surfaces of the motor were measured. Dramatic differences between the roughness of the underside and top surfaces of the rotor and between the surface beneath the rotor and adjacent areas were observed. The mechanisms responsible for stiction in such devices are discussed. Lubrication methods to minimize friction problems are also presented.

Keywords
  • Friction,
  • Atomic force microscopes,
  • micromotors,
  • friction force microscopes,
  • surface measurements
Publication Date
2001
Publisher Statement
Copyright 2001 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
Citation Information
Sriram Sundararajan and Bharat Bhushan. "Static friction and surface roughness studies of surface micromachined electrostatic micromotors using an atomic force/friction force microscope" Journal of Vacuum Science and Technology A Vol. 19 Iss. 4 (2001)
Available at: http://works.bepress.com/sriram_sundararajan/15/