Bioinspired Fabrication of Bi/Tridirectionally Anisotropic Sliding Superhydrophobic PDMS Surfaces by Femtosecond Laser

Abstract Precisely arranged multiscale microstructures in living systems provide inspirations for the fabrication of artificial advanced materials and devices. Recently, uni‐bioinspired surfaces with anisotropic wettability are built for various applications. Here, a kind of bi‐bioinspired (rice leaf and butterfly wing) tridirectionally anisotropic sliding superhydrophobic surface for the first time is reported. First, a microgroove array structured polydimethylsiloxane surface is constructed by selective femtosecond laser ablation. The as‐prepared surface shows bidirectional anisotropy which can be easily tuned by the width ( L ) and the depth of the microgrooves. A “steps” structure is further introduced into the microgrooves. Interestingly, tridirectionally anisotropic sliding superhydrophobicity that combined the rice‐leaf‐like and butterfly‐wing‐like anisotropy is achieved on such surface. The tridirectional anisotropy is demonstrated to result from the directional “steps” structures and the uneven distribution of rough structures. The bi/tridirectionally anisotropic sliding property will provide a fresh cognition of anisotropic wettability for researchers and have enormous potential applications in smart microfluidic systems.