Adhesion Mechanism of Water Droplets on Hierarchically Rough Superhydrophobic Rose Petal Surface

Extremely hydrophobic surfaces, on which water droplets sit in a spherical shape leaving air entrapped into the roughness of
the solid, are often called superhydrophobic. Hierarchically rough superhydrophobic surfaces that possess submicron scale fine
structures combined with micron scale structures are generally more hydrophobic, and water droplet adhesion to those surfaces is
lower in comparison with surfaces possessing purely micrometric structures. In other words, usually a fine structure on a superhydrophobic
surface reduces liquid-solid contact area and water droplet adhesion. Here we show that this does not apply to a highadhesive
superhydrophobic rose petal surface. Contrary to the present knowledge, the function of the fine structure on the petal
surface is to build up the high adhesion to water droplets. Understanding of the specific adhesion mechanism on the rose petal gives
insight into an interesting natural phenomenon of simultaneous superhydrophobicity and high water droplet adhesion, but, in
addition, it contributes tomore precise comprehension of wetting and adhesion mechanisms of superhydrophobic surfaces overall.