Bio-Inspired Porous Aluminum Surfaces for Enhanced Water Collection

The ability to accelerate any step in the condensation process is the key to obtaining efficient water collection from atmosphere. Bio-inspired functional surfaces can be applied to enhance water collection with special morphology and wettability. Here, water collection from air is demonstrated with the porous stripe patterned aluminum surfaces inspired from the directional water droplet rolling in line patterns of rice leaf and water absorption in pore structures of moss Rhacocarpus purpurescens. Several types of surfaces are prepared such as a bare hydrophobic surface, a porous superhydrophilic surface, a porous superhydrophobic surface, a porous superhydrophilic stripes on bare hydrophobic surface, and a porous superhydrophobic stripes on bare hydrophobic surface. Among them, the superhydrophilic stripes patterned hydrophobic surface shows the best water collection efficiency leading to 147% increase in water collection rate compared to that of bare aluminum surface. The contrast in wettability and morphology creates confined anisotropic line boundary for water droplet growth as well as strong surface energy driven-unbalanced force and capillary-driven force for water droplet movement. Consequently, the porous stripe patterned aluminum surfaces result in promotion of coalescence and easy removal of condensates. This bio-inspired surface allows effective surface condensation showing the potential in various water management systems.