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∗=4η∗=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 ηη decreases linearly with the critical value of the Casimir force parameter.