CPM Seminar

Femtosecond laser micromachining of materials to engineer functional surfaces

Anne Marie Kietzig

Department of Chemical Engineering
McGill University

Functional surfaces in Nature are often characterized by patterns of similar multi-length scale surface features of regular but random geometry. In science and engineering we prefer precise feature geometries that are accessible by mathematical formulations for kinetic and thermodynamic considerations. Engineered multi-length scale features typically result from complicated multiple processing steps under controlled environments requiring various equipment. Femtosecond (fs) laser machining has emerged in the past decades as a versatile material processing technique which requires only one single process step to induce either random multi-length scale features or microstructures of closely controlled geometry. The characteristic short pulse duration results in very localized heat effects that allows structuring material surfaces without affecting the underlying bulk properties. There is no limit to the material type that can be machined with lasers, however, the topological outcome is a direct response dictated by the respective material’s properties. Next to altering the surface topology of materials, the laser irradiation also often causes changes in a surface’s chemistry. Specifically, the surface chemistry of metals undergoes significant changes after laser micromachining and over time. Owing to the consequently widely observed (yet poorly understood) progressive decrease in wettability of metals upon laser-machining in ambient conditions coupled with the ease of manufacturing hierarchical surface features, laser-micromachined surfaces have triggered interest for many different applications, such as non-adhesive, anti-icing, extreme wetting and non-wetting, easy flow and drag reducing surfaces.