Laser-processed functional surface structures for multi-functional applications-a review

Functional surface structures, which are of certain shapes and surface morphologies for specific functions, have been widely applied in a wide range of optical, thermal, electronic, energy, mechanical, and biomedical areas. The demand for high-performance functional surface structures has spurred an urgent need for their fabrication with high precision, good flexibility, low cost, and environmental friendliness. Laser processing technologies with high precision, simple operation, excellent flexibility, and compatibility for diverse materials have become a research hotspot for the fabrication of functional surface structures in recent years. To overview this subject, recent advancements in various laser-processed functional surface structures are comprehensively reviewed in this paper. To the best knowledge of the authors', it is the first time to systematically present the advancements of laser-processed functional surface structures for multi-functional applications. Firstly, common laser processing methods for functional surface structures, including direct laser ablation, direct laser interference patterning, pulsed laser deposition, and selective laser melting, are introduced briefly. Typical laser-processed functional surface structures are presented, such as laser-induced periodic surface structures, microchannels or microgrooves, microholes, micropillars, porous structures, and hierarchical structures. Subsequently, the laser-processed functional surface structures are systematically classified into six types according to their functional applications, i.e., optical, thermal, electronic, tribological, biomedical, and biomimetic superhydrophobic functional surface structures. The performance of each type of structures is also summarized and discussed. Finally, the challenges and potential futural research directions of the laser-processed functional surface structure are clarified.