Through natural evolvement in thousands of years, biosurfaces have become highly adaptable to display their biological functions perfectly. Interestingly, they have developed micro-/nanostructures with gradient features to achieve smart wetting controls, such as ultra-hydrophobic water repellency in lotus leaf, directional water collection in wetted spider silk, directional adhesion in superhydrophobic butterfly wing, and fog-collecting hydrophobic/hydrophilic pattern on beetle back. These surfaces provide endless inspiration for the design and fabrication of functional interface materials...