Fabrication and Wetting Properties of Metallic Half-Shells with Sub-Micron Diameters
This paper presents work from Love, et al. concerning fabrication of metallic shells. Thin metallic shells are deposited on and then released from spherical molds. Treated with self-assembled monolayers, aggregates of these shells can be made superhydrophobic. In addition to forming structures that affect the wetting properties of a surface, it is postulated that the thin, metal edges of the half-shells can provide strong enhancements in optical and magnetic fields.
Fabrication of Half-Shells
As illustrated in the figure, fabrication of the half-shells occurs in four main steps:
- - monolayers or multilayer of silica colloids are prepared by drop-casting aqueous suspensions of the particles onto glass slides
- - an adhesion layer of titanium or nickel followed by a thin film of gold, platinum, or palladium are deposited onto the colloids via electron-beam evaporation
- - spherical colloids are released from the glass slide by sonication
- - silica and adhesion metal are dissolved by etching the colloids in hydrofluoric acid (HF), leaving only the thin shell