Strong geometry dependence of the Casimir force between interpenetrated rectangular gratings

Quantum fluctuations give rise to Casimir forces between two parallel conducting plates, the magnitude of which increases monotonically as the separation decreases. By introducing nanoscale gratings to the surfaces, recent advances have opened opportunities for controlling the Casimir force in complex geometries. Here, we measure the Casimir force between two rectangular silicon gratings. Using an on-chip detection platform, we achieve accurate alignment between the two gratings so that they interpenetrate as the separation is reduced. Just before interpenetration occurs, the measured Casimir force is found to have a geometry dependence that is much stronger than previous experiments, with deviations from the proximity force approximation reaching a factor of ~500. After the gratings interpenetrate each other, the Casimir force becomes non-zero and independent of displacement. This work shows that the presence of gratings can strongly modify the Casimir force to control the interaction between nanomechanical components.

Influence of Accelerating Force on the Electromechanical Instability of Paddle-Type and Double-Sided Sensors Made of Nanowires

The double-sided and paddle-type nanostructures are promising for developing miniature accelerometers. In the present work, the impact of the accelerating force on the pull-in performance of the double-sided and paddle-type sensors fabricated from nanowire are investigated. The proximity force approximation (PFA) is employed to consider the effect of Casimir attraction in the theoretical model. Using the modified couple stress theory, the constitutive equations of the sensors are derived. The governing equations are solved by two different approaches, i.e. modified variational iteration method (MVIM), and finite difference method (FDM). The influences of the Casimir and accelerating forces, geometrical parameters and the size phenomenon on the pull-in parameters are demonstrated.