Bionic wrinkle structure for efficient water collection inspired by skin

Abstract

Water collection from the air is a convenient and efficient solution to the freshwater shortage. However, the lack of geometry-driven structures limits the development of high-efficiency water collection devices. Therefore, we have devised a new structure with a Janus membrane that mimics skin folds, which spontaneously drive droplets in a specific direction. Theoretical analysis suggests that the wrinkling surface produces a driving force that regulates the droplet speed. And as the degree of the wrinkles' deformation increases, so does the efficiency of collecting fog. The highest water collection efficiency can reach 5.03 times that of the control group calculated by the projected area, and 2.51 times calculated by the real area. Simulations demonstrate that the geometric and wetting gradients contribute to efficient droplet removal, and the flow field altered by wrinkles is beneficial to rapid droplet nucleation, contributing to high efficiency. Even if a flexible base is simply squeezed into a wrinkle, which can also improve the fog-harvesting efficiency by 0.29 times calculated by the real area. Consequently, this bionic wrinkle can be applied to other flexible water collection structures, bringing a new dawn to the improvement of water collection efficiency.