Influence of van der Waals and Casimir Forces on Electrostatic Torsional Actuators

Abstract

The influence of van der Waals (vdW) and Casimir forces on the stability of the electrostatic torsional nanoelectromechanical systems (NEMS) actuators is analyzed in the paper. With the consideration of vdW and Casimir effects, the dependence of the critical tilting angle and pull-in voltage on the sizes of structure is investigated. And the influence of vdW torque is compared with that of Casimir torque. The modified coefficients of vdW and Casimir torques on the pull-in voltage are, respectively, calculated. When the gap is sufficiently small, pull-in can still take place with arbitrary small angle perturbation because of the action of vdW and Casimir torques even if there is not electrostatic torque. And the critical pull-in gaps for two cases are, respectively, derived.[1222]Index Terms-Casimir, electrostatic torsional actuator, M/NEMS, pull-in, van der Waals (vdW).

Instability analysis of torsional MEMS/NEMS actuators under capillary force

“…[16], the influence of the vdW and Casimir effects on the inherent instability of an electrostatic torsional NEMS actuator was studied. We can compare the vdW and Casimir effects with capillary effects.…”

“…And they always exist between two objects close to each other. The influence of vdW and Casimir forces on the stability of the MEMS and NEMS actuators with suspended structures has been extensively reported in many literatures [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Chan et al [10] showed that Casimir force can be used to actuate the NEMS devices under certain condition.…”

“…They also studied the dynamic behavior of the parallel plate NEMS RF switches with the consideration of the vdW effects [14]. Guo and Zhao [16] studied the inherent instability of an electrostatic torsional NEMS actuator with the vdW and Casimir effects taken into consideration, and derived the critical conditions when the pull-in phenomena of the actuator occurred. The influence of vdW force on dynamic stability of an electrostatic torsional NEMS actuator was also studied [17], and the bifurcation behaviors were analyzed.…”

A modified model for stability analysis of narrow-width NEMS tweezers: Corrections due to surface layer, scale dependency and force distributions

“…As the dimensions of electromechanical systems reduce, dispersion forces, i.e. Casimir and van der Waals (vdW) attractions, appear [6][7][8]. At separations typically less than several micrometers, the dispersion forces between interacting surfaces can be described by the well-known Casimir force [6].…”

“…However, when the retardation is not signi cant, i.e. the separation is less than several ten nanometers, the quantum interactions should be modeled as vdW attraction [2,7,8].…”