Authors: P. Guidotti and D. Bernstein
Affilation: California Institute of Technology, United States
Pages: 306 - 309
Keywords: electrostatic, actuator, MEMS, hysteresis, pull-in
We investigate the relationship between the pull-in phenomenon for electrostatic actuators and the hysteresis effect found in zipper actuators. Liked lumped mass and spring and tension based membrane models, we show that a beam model of a simple electrostatic actuator device has a fold and a corresponding pull-in voltabe. When a dielectric layer is added to the model, however, the fold disappears for certain values of the dielectrice constant and layer thickness. We use a variational formulation of the model to compute the location of the zipped states and show that the disappearance of the fold corresponds to the disappearance of the hysteresis effect in the zipper actuator. Hence the existence of the fold, and of the corresponding unstable state, is crucial for understanding the hysteresis observed in previous studies of zipper actuators.