3D-printed mesh membranes with controllable wetting state for directional droplet transportation

Abstract

Mesh membranes have a wide range of applications including fog harvesting and oil-water separation. However, due to the wetting energy barrier, water droplets are usually pinned in the meshes and there are still substantial difficulties in achieving directional transport. In this paper, mesh membranes for directional droplet transport are achieved by controlling the surface wetting state with sub-millimeter structures. The effect of mesh structures on the surface wetting state is studied theoretically. And accordingly, a unique filament stack structure is presented to acquire the desired wetting state, which can be further switched on-demand by incorporating the filament swelling. The well-designed mesh structures can be 3D printed efficiently without post-processes such as surface modification. It provides a facile and effective way to develop scalable mesh membranes for directional and selective droplet transport.