Superior lubrication properties of biomimetic surfaces with hierarchical structure

In this study, a new method to fabricate biomimetic engineering surfaces with lotus leaf-like hierarchical microstructures is explored. Contact angle tests were performed to study the influences of the structures on the surface hydrophobic properties. Air lubrication resulted in hydrophobicity and consequently reduced the liquid-solid contact. The superior lubrication behaviour of a biomimetic hierarchical surface was observed by tribology experiments. Simulation results indicated that by improving hydrophobicity, the frictional drag was reduced by a significant amount because of the large fraction of air. It was found that introducing the superposition of microscale hemispherical papillae and branch-like nanostructures has a dramatic positive effect in reducing frictional drag results because 99% of liquid-solid interface was replaced by air-liquid interface.