Fabrication of high aspect ratio silicon micro-/nano-pore arrays and surface modification aiming at long lifetime liquid-infused-type self-cleaning function

Abstract

This paper discusses a fabrication process of high aspect ratio (AR) silicon micro-/nano-pore structures and modification of their surfaces to improve the function of liquid-infused-type self-cleaning surfaces. The structure and its hydrophobic surface play an important role to hold a special liquid (a lubricant) on the surface tight to produce an intermediate lubricant layer and any liquid drops, including low surface tension liquids such as oil, can slide easily on it. The nanopore structure with an AR as high as 30 was fabricated by etching in a solution of hydrofluoric acid and hydrogen peroxide. This process based on a catalyst reaction of an array of Au islands that was deposited on a silicon substrate through a particle mask. This original hydrophilic surface was changed to hydrophobic one by depositing self-assembled monolayer of octadecyltrichlorosilane to modify the energy balance at the interface of the solid structure, the lubricant, another liquid, and air. Then the lubricant could be well retained. The functional lifetime was evaluated by measuring the liquid residue on the surface after number of liquid dash. It was confirmed that longer lifetime was obtained with higher AR nanopore structure.

Keywords

• structured surface
• self-cleaning
• metal-assisted chemical etching
• self-assembled monolayer (sam)
• liquid-infused surface
• lifetime