Direct laser texturing technique for metal surfaces to achieve superhydrophobicity

Superhydrophobic surfaces have been a popular research topic in the research communities due to disruptive innovations in a variety of applications. The synergistic effect of rough surface geometry and low-surface-energy chemicals is widely acknowledged to be critical for achieving superhydrophobicity, particularly on metal surfaces. Laser texturing is a facile, efficient, flexible and highly accurate technique for developing rough surface geometries. However, low-surface-energy treatments are difficult to remove from current superhydrophobic surfaces. We review here the direct laser texturing technique for creating superhydrophobic surfaces on metals, with a focus on the lack of any chemical treatment during fabrication. Laser texturing parameters, surface geometry changes and wetting transformation processes are discussed in detail. Along these lines, we summarize the mechanism of the wetting transformation from the hydrophilic to the superhydrophobic state and present current challenges. The large-scale, environmentally friendly, cost-effective and one-step fabrication of superhydrophobic surfaces on metals will be introduced on the basis of this impressive laser surface treatment technique. A huge focus will be devoted to the development of stimulus-responsive surfaces with reversible wetting switches for surface icephobicity, condensation inhibition, corrosion resistance, fluid drag reduction, directional collection, transport and manipulation of liquids and applications in the fields of aerospace, marine, power systems, transportation and microfluidic devices.