4D printing of butterfly scale-inspired structures for wide-angle directional liquid transport

• Main Authors: Liu, Xiaojiang, Li, Boyuan, Gu, Zhongze, Zhou, Kun
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering::Mechanical engineering; 4D Printing; Butterfly Scale
• Online Access: https://hdl.handle.net/10356/170335
• Institution: Nanyang Technological University

Unidirectional liquid transport has been extensively explored for water/fog harvesting, electrochemical sensing, and desalination. However, current research mainly focuses on linear liquid transport (transport angle α = 0°), which exhibits hindered lateral liquid spreading and low unidirectional transport efficiency. Inspired by the wide-angle (0° < α < 180°) liquid transport on butterfly wings, this work successfully achieves linear (α = 0°), wide-angle, and even ultra-wide-angle (α = 180°) liquid transport by four-dimensional (4D) printing of butterfly scale-inspired re-entrant structures. These asymmetric re-entrant structures can achieve unidirectional liquid transport, and their layout can control the Laplace pressure in the forward (structure-tilting) and lateral directions to adjust the transport angle. Specifically, high transport efficiency and programmable forward/lateral transport paths are simultaneously achieved by the ultra-wide-angle transport, where liquid fills the lateral path before being transported forward. Moreover, the ultra-wide-angle transport is also validated in 3D space, which provides an innovative platform for advanced biochemical microreaction, large-area evaporation, and self-propelled oil-water separation.