MEMS and sensors

What is the driving principle of the "comb-drive" structure used as a MEMS actuator?

  1. AElectrostatic attraction when a voltage is applied between interdigitated comb-shaped electrodes
  2. BElectromagnetic force from magnets and coils
  3. CThermal expansion
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Answer: A. Electrostatic attraction when a voltage is applied between interdigitated comb-shaped electrodes

A comb-drive actuator applies a voltage between interdigitated fixed and movable comb-shaped electrodes and moves the movable part by electrostatic attraction. More comb fingers give more force, and the force stays nearly constant over the travel. It is used in resonant gyroscopes, optical switches and similar devices.

  • A. Correct. Electrostatic attraction between comb electrodes moves it.
  • B. This differs from electromagnetic actuation, which uses magnetic force.
  • C. This differs from thermal actuation, which uses thermal expansion.
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