Engineered Bio-inspired Geometrically Complex Water-repellent Surfaces and Their Applications

In nature, various plants and animals exhibit promising structurally-defined functionalities. Many discoveries of efficient water-repellent surfaces in nature have promoted research into engineering bio-inspired artificial structures with superhydrophobicity, due to their huge potential impacts on various applications, such as water-repellency, self-cleaning, condensation acceleration, and drag reduction. In particular, Nelumbo nucifera (lotus leaf), has been extensively studied in an effort to replicate its excellent superhydrophobic and low water adhesive characteristics. According to the inspiration driven from the lotus leaf, the stable combination of chemical modification (e.g. hydrophobic fluoro-silane treatment) and increased surface roughness (e.g. increasing levels of structural hierarchy) is the most important factor to obtain efficient water-repellency. However, most existing manufacturing techniques using a lithographic or molding approach have typically involved only one, or occasionally two, length-scales of roughness, and have not been successful enough to mimic the complex geometries of a biological epidermis, such as the lotus leaf or taro leaf.In this research, in order to achieve a closer resemblance to the Nelumbo nucifera and to obtain even better water-repellent performance, we will introduce various manufacturing breakthroughs and in-depth investigations into novel micro- and nano- manufacturing processes for bio-inspired geometrically complex structures. This research on efficient water-repellency makes extensive contributions in the field of wettability, e.g. microfabrication research, biomimetics, and related fundamental wettability theories