TABLE OF CONTENTS Electrostatic forces are very well adapted to actuate elementary micro-structures or more complex micro-mechanisms thanks to their high intensity with short range interaction. A pioneering demonstrator, published in 1977, presented an array of micro-cantilevers, whose deflections were controlled by electrostatic forces [PET 77]. Since then, numerous electrostatic micro-actuators have been proposed and manufactured, among them mechanical oscillators, rotating micro-motors, linear displacement devices and micro-pumps. These micro-actuators are described according to their basic topology in this contribution, once the general principle of electrostatic forces and their equilibrium are introduced.
An efficient adaptation of electrostatic force to micro-dimensions is easily explained by Coulomb's law:
This expresses the force exerted by the charge q ' on the charge q, separated by a distance r. The unit vector u qq, is oriented from q' to q and ? 0 is the vacuum permittivity. It is obvious that these forces become larger when the distances, r, are reduced ( r ?2). With the same distance variation, the gravity forces ( r 3) and elastic restoring forces ( r 2) decrease, and the effect of electrostatic forces therefore becomes significant and even dominant with the reduced sizes of the micro-structures. The electrostatic force intensity can be easily controlled by the applied...
