The strain gradient effect in microelectromechanical systems (MEMS)

Metallic materials display strong size effect when the characteristic length of deformation is on the order of microns. The theory of mechanism-based strain gradient (MSG) plasticity established from the Taylor dislocation model has captured this size dependence of material behavior at the micron scale very well. The strain gradient effect in microelectromechanical systems (MEMS) is investigated in this paper via the MSG plasticity theory since the typical size of MEMS is on the order of microns (comparable to the internal material length in MSG plasticity). Through an example of a digital micromirror device (DMD), it is shown that the strain gradient effect significantly increases the mechanical strain energy in the DMD, and reduces the rotation time of the micromirror. However, the strain gradient has no effect on the critical bias voltage governing the fast rotation of the micromirror.