Analytical Calculations for Nanoscale Electromechanical

Nano electromechanical systems NEMS become an essential part of modern sci ence and technology A number of applications is already known nanomanipu lation nanosensors medical devices nano uidic devices to name a few Even more applications are anticipated to follow the technological progress in this eld I address in this paper one of issues arising when we try to understand phenomena happened at the nanoscale with theoretical tools borrowed from an experience of macroscopic physics The latter has to reach its limits and micromodels are required for a quantitative description of a nano device However an essential part of the theory bases on very general assumptions For example a continuum modeling gives a perfect description of systems of atomic scale when using a microscopically derived parameterization for the theory The aim of this paper is to derive an atomistic correction for a micro scale mod eling and to discuss limits of applicability of simplest models The object of study is a nano electromechanical switch Main changes in its operation at the nanoscale are related to an importance of van der Waals forces These forces will change param eters describing the equation of state of a NEMS All derivation will be performed analytically which allows one to apply this theory to a broad class of devices I will demonstrate how the van der Waals interaction changes two main parameters describing an instability point of a NEMS device which are a pull in voltage and a pull in gap The calculation is done within a continuum model It allows to develop a common analytical approach for nanoscale switches of various geometry various size and various material properties I stress that the model includes a general form of the free energy The free energy of the system may be comprised of several terms Corresponding gradients of the energy components are forces acting on the NEMS In particular I