What Is a Comb Drive?

Comb actuation is a type of actuator, which is usually driven by the electrostatic force of two conductive comb teeth ^[1] . Comb actuators are typically applied on the micron or nanometer scale and are made from silicon wafers produced by block micromachining or surface micromachining.

When a voltage is applied to a fixed comb tooth and a moving comb tooth, an electrostatic force is generated between the two and attracts each other. The amount of force generated by the actuator is proportional to the change in capacitance between the comb teeth; the size of the driving voltage, the number of comb teeth, and the gap between the comb teeth will also be affected. The comb teeth are designed so that they do not touch each other (because then there is no voltage difference). Generally, it is designed that each tooth can slide over another tooth and snap into the corresponding groove.

If the linear operation of the motor is converted into rotation or other motion, the spring,

• Rows of comb teeth that can be snapped into each other, one half is fixed, the other half is movable, and is electrically isolated

• Electrostatic attraction / repulsion

• CMOS driving voltage

• Increase the number of teeth to produce more force (usually 10 m)

The comb actuator cannot increase the gap (equivalent to the driving distance) too much. Because the larger the gap, the greater the required drive voltage. Therefore this part will be limited by electrical breakdown. More importantly, the limitation of the gap size is equivalent to the limitation of the driving distance.