Interaction of a falling water droplet with an elastic superhydrophobic surface: Enhanced droplet jump-off force

In this study, high-speed imaging and a position-sensing detector were used to observe the interactions between a falling water droplet and an elastic superhydrophobic surface. The magnitudes of the droplet forces were calculated based on the measured surface displacements. The superhydrophobic surface was deflected downward by the inertial shock upon droplet impact. The elastic energy stored on the surface after droplet impact recovered as the drop bounced off the surface. This phenomenon resulted in a larger droplet jump-off force than that on the rigid superhydrophobic surface. The jump-off force deflected the surface downward again, resulting in a “double minima” in the evolution of the surface displacement. The variation in the magnitude of the double minima with respect to the Weber number was estimated accurately using the scaling argument derived from energy conservation.