Natural and artificial surfaces with superwettability for liquid collection

Surfaces with superwettability have many remarkable prospective applications, of which their use for liquid collection is attracting more and more attention worldwide. As typical examples of water collection from foggy atmospheres, Namibian desert beetles, spiders, and cactus make full use respectively of their patterned backs with contrast wettability, spider silks with periodic spindle-knots and joints, and spines with multi-level structures to directionally transport the water collected to specific positions, respectively. Guided by these structure-function relationships and following the similar principles, researchers have developed many methods to fabricate artificial desert beetles, artificial spider silks, and artificial cactus spines, resembling not only the microstructures and surface wettability but also functions to collect liquid directionally. This chapter mainly aims to give an introduction to liquid collection on those natural and artificial organisms, with a brief conclusion and outlook.