Analytical study on size-dependent static pull-in analysis of clamped-clamped nano-actuators in liquid electrolytes

In this study, based on the modified couple stress theory, size-dependent static behavior of clamped-clamped actuators in liquid electrolytes is investigated considering the effects of van der Waals force and the nonlinearities caused by mid-plane stretching and residual forces. The minimum total potential energy principle is used to derive the nonlinear governing integro-differential equation which is then solved using the modified Adomian decomposition (MAD). It is seen that the results computed by MAD are in good agreement with the numerical results, even as the nano-actuators approach their stability limits. Influences of ionic concentration, residual stress and mid-plane stretching on the static pull-in instability of the clamped-clamped actuators are studied. It is found that the size effect is significant when the ionic concentration is high, but it is diminishing with the decrease of the ion concentration. The findings indicate that increasing the residual stress, mid-plane stretching force and ionic concentration increases the pull-in voltage of the nano-actuators.