Bioinspired micro/nanostructured surfaces prepared by femtosecond laser direct writing for multi-functional applications

Femtosecond laser direct writing (FLDW) has been widely used for controllable biomimetic micro/nanostructure processing due to its specific advantages including high precision, simplicity, and compatibility for diverse materials in comparison with other methods (e.g. ion etching, sol-gel process, chemical vapor deposition, template method, and self-assembly). These biomimetic micro/nanostructured surfaces are expected to be broadly applicable in self-cleaning, oil-water separation, and fog collection, which have attracted increasing attentions ranging from academic research to industrial applications in recent years. In this review, we firstly present the inherent relationship among nature organisms, fabrication methods, micro/nanostructures and their potential applications. Thereafter, we throw a list of current fabrication strategies so as to highlight the advantages of FLDW in manufacturing bioinspired microstructured surfaces. Subsequently, we summarize a variety of typical bioinspired design (e.g. lotus leaf, pitcher plant, rice leaf, butterfly wings and so on) for diverse multifunctional micro/nanostructures through extreme femtosecond laser processing. On the basis of the principle of interfacial chemistry and geometrical optics, we present some potential applications of these functional micro/nanostructures in the fields of structural color, self-cleaning, oil-water separation, fog harvesting, underwater bubble collection, droplet directional transport and droplet/optical switch. Finally, we propose some underlying challenges and opportunities in the extreme fabrication of bioinspired micro/nanostructures by FLDW, and follow the outlook of the development in terms of femtosecond laser processing in biomimetic domains.