摘要
The symmetry of the electric field in a dielectric medium sandwiched between comb-fingers dominates the stability of the comb-drive actuator. The stability can be spontaneously broken by the asymmetry appearing on the two sides of the finger array. A quite universal circuit simulator (Qucs) equivalent circuit model was built to illustrate that the symmetry is not preserved in the outer four comb-fingers, especially the first and last fingers, because they are subjected to unbalanced electrostatic forces. Experiments were conducted to verify the proposed Qucs model, which also demonstrated that symmetry exists everywhere in an imaginary comb-finger array with infinite interdigitaed fingers. In this work, the ideal comb-finger array can be nearly realized by making the two outermost fingers five times wider than the others; as a result, the symmetry is preserved and the instability is effectively suppressed in the comb-finger array. © 2011 IOP Publishing Ltd.