Modification of wettability by surface structures created by fs-laser ablation on Si

The ability to modify the wettability of surfaces is crucial for various applications. For example, it allows to expand the healthspan by providing advanced medical implants and medications, to reduce waste through corrosion and fouling prevention and to cut emissions through efficient use and generation of energy. Traditional approaches based on chemical treatments and coatings often lack long-term stability and frequently come with environmental or health risks. As an alternative, this thesis explores the modification of the wettability through laser-based surface structuring on silicon, using fs-laser ablation. As a starting point, four surface structures from literature were reproduced. Subsequently, four additional structure with modified geometries compared to the initial ones were processed. In addition, a systematic screening for hydrophobicity by varying diameter or width, depth and period distance of the ordered geometric features for three selected structure geometries, namely Grid, Hole and Spike structures, was conducted. The created structures were evaluated using laser scanning confocal microscopy, scanning electron microscopy and qualitative wettability assessment by classification into four wetting regimes. All structures could be successfully manufactured and a pronounced superhydrophilic behavior was observed for tube structures. A decrease in wettability was only detected for the small hole structure, showing weak hydrophilic behavior. No transition to hydrophobicity or superhydrophobicity could be observed. Future research should continue to explore how laser generated structures and their substructures influence the stability of the gas accumulation in the structure.