Droplet-induced abnormal bending of micro-beams

摘要

We present a theoretical study of the abnormal deformation of micro-beams induced by a droplet placed on their top/bottom surfaces. The bending moments and deflections of the micro-beams are derived in consideration of the surface tension and Laplacian pressure difference of the droplet. The deflection curves show that the cantilever inevitably tilts upwards with a droplet on its top surface, and most parts of the simply supported beam and clamped-clamped beam will bend upwards when a droplet is adhered to their bottom surfaces. These anomalous deformation behaviors have been verified by our finite element simulations. We also demonstrate what extent of the boundary conditions will affect the deflection curves of the micro-beams during the variation of the droplet's parameters. Understanding this abnormal bending mechanism of the beams can be beneficial to some industry applications, such as the micro-electro-mechanical systems (MEMS) and the microano-measurement, which can provide the inspiration of engineering more precision micro-sensors.