A good source for this is

 Rob Legtenberg, AW Groeneveld and M Elwenspoek, Comb drive actuators for
large displacements, Micromech.Microeng (1996) 320-329

It has all of the formulas and derives them.

Shane McColman
Research Professional
NanoFab, University of Alberta
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Edmonton AB, Canada, T6G 2V4
Tel: (780) 492-8357
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