A pull-in parameter analysis for the cantilever NEMS actuator model including surface energy, fringing field and Casimir effects

In this paper, the pull-in instability of a cantilever nano-actuator is considered incorporating the influence of surface effects, the fringing field and the Casimir attraction force. The instability parameters of the actuator are determined analytically under the assumption of a second-degree shape function for the beam during deflection. The influence of surface effects, the Casimir force and the fringing field effects on the pull-in parameters is investigated. The results demonstrate that the Casimir force decreases the pull-in deflection and voltage, the fringing field effects increase the pull-in deflection and decrease the pull-in voltage. The critical value of the surface effect parameter decreases monotonically from η ∗ = 4 as the Casimir force parameter increases. In the presence of the Casimir force, the surface effects decrease the pull-in deflection and voltage. For the MEMS model, which neglects the intermolecular forces, the surface effects do not influence the pull-in deflection, but decrease the pull-in voltage. For freestanding nanoactuators, the critical values of the tip deflection and the Casimir force parameter are obtained, and the surface effect parameter η decreases linearly with the critical value of the Casimir force parameter.