A 2-DOF model for incorporating the effect of microstructure on the coupled torsion/bending instability of nano-mirror in Casimir regime

摘要

It has been well-established that the physical performance of nano-devices might be affected by the microstructure. Herein, a 2 degree-of-freedom model based on modified couple stress elasticity is developed to incorporate the impact of microstructure in the torsion/bending coupled instability of rotational nano-scanner. The governing equation of the varactor is derived incorporating the effects of electrostatic Coulomb and corrected Casimir forces with the consideration of the finite conductivity of interacting surfaces. Effect of microstructure-dependency on the instability parameters are determined as a function of the microstructure parameter, bending/torsion coupling ratio, vacuum fluctuation parameter and geometrical dimensions. It is found that the bending/torsion coupling substantially affects the stable behavior of the scanners especially those with long rotational beam elements. Depending on the geometry and material characteristics, the presented model is able to simulate both hardening behavior (due to size phenomenon) and softening behavior (due to torsion/bending coupling) of the nano-mirror.