Droplet motion on flexible superhydrophobic porous sponge surface

Abstract

Droplet capture and release are very significant for droplet manipulation on a superhydrophobic surface. Once the aqueous droplets impact the stiff superhydrophobic surface, they easily detach from the surface and generate chaotic motion without much energy loss. Thus, it is difficult to catch and manipulate the droplets falling on these kinds of surfaces. In this study, a droplet was captured after impacting the superhydrophobic porous sponge. Most of the kinetic energy of a falling droplet is transferred into the elastic potential energy of a sponge. The absorbed energy in the deformation process and the elastic modulus of sponge were adjusted by the porosity of the sponge. With the decrease in density, the elastic modulus of the sponge decreases, and the energy loss increases. During the droplet impacting process, the sponge with smaller elastic modulus can obtain much more energy from the droplet, which makes it easy to drag and capture the droplet. This new design also has other potential applications, such as water collection and fog harvest.