3D bioinspired microstructures for switchable repellency in both air and liquid

• Main Authors: Liu, Xiaojiang, Gu, Hongcheng, Ding, Haibo, Du, Xin, Wei, Mengxiao, Chen, Qiang, Gu, Zhongze
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2021
• Subjects: Engineering::Mechanical engineering; 3D Printing; Liquid Responsive Bending
• Online Access: https://hdl.handle.net/10356/148817
• Institution: Nanyang Technological University

In addition to superhydrophobicity/superoleophobicity, surfaces with switchable water/oil repellency have also aroused considerable attention because of their potential values in microreactors, sensors, and microfluidics. Nevertheless, almost all those as-prepared surfaces are only applicable for liquids with higher surface tension (γ > 25.0 mN m-1) in air. In this work, inspired by some natural models, such as lotus leaf, springtail skin, and filefish skin, switchable repellency for liquids (γ = 12.0-72.8 mN m-1) in both air and liquid is realized via employing 3D deformable multiply re-entrant microstructures. Herein, the microstructures are fabricated by a two-photon polymerization based 3D printing technique and the reversible deformation is elaborately tuned by evaporation-induced bending and immersion-induced fast recovery (within 30 s). Based on 3D controlled microstructural architectures, this work offers an insightful explanation of repellency/penetration behavior at any three-phase interface and starts some novel ideas for manipulating opposite repellency by designing/fabricating stimuli-responsive microstructures.