Modeling the electromechanical behavior and instability threshold of NEMS bridge in electrolyte considering the size dependency and dispersion forces

摘要

While few studies have been conducted on modeling the pull-in instability of cantilever nanoelectromechanical systems (NEMS) in electrolyte media, no researchers has investigated this phenomenon in double-clamped NEMS. Herein, the pull-in instability of the NEMS bridge immersed in ionic liquid electrolyte media is explored for the first time considering the size effect and dispersion forces. The strain gradient elasticity in conjunction with von-Karman strain is employed to incorporate the effect of size-dependency and beam stretching in the structural model. The presence of electrochemical force field and nano-scale attractions i.e. Casimir and van der Waals forces is incorporated in the model considering the presence of the liquid media. To solve the nonlinear constitutive equation of the system two different methods including the differential transformation method (DTM) and numerical solution are employed. The proposed model is validated by comparing with the results presented in literature. Impacts of various parameters i.e the size dependency, dispersion forces, electrolyte ion concentration and potential ratio on the instability characteristics of the NEMS bridge are discussed. The results of present theory are compared with those predicted by the classic continuum theory as well as the modified couple stress theory. (C) 2015 Elsevier B.V. All rights reserved.