3D Microprinting of Super‐Repellent Microstructures: Recent Developments, Challenges, and Opportunities

Abstract Liquid super‐repellent surfaces, characterized by a low liquid–solid contact fraction, allow various liquids to bead up and freely roll off. Apart from liquid repellency, these surfaces feature several unique properties, including inter alia, self‐cleaning, low‐friction, anti‐icing, and anti‐biofouling, making them valuable for a vast array of applications involving liquids. Essential to achieve such super‐repellency is the bio‐inspired reentrant or doubly reentrant micro‐topography. However, despite their unique interfacial properties, the fabrication of these delicate 3D topographies by conventional microfabrication methods is extremely challenging. Recently, emerging 3D microprinting technologies, particularly two‐photon lithography, have brought new scope to this field. With unparalleled design freedom and flexibility, 3D microprinting greatly facilitates the design, testing, and studying of complex 3D microstructures. Here, applications of 3D microprinting in the design and fabrication of super‐repellent microstructures are summarized, with a focus on their remarkable properties, and new functionalities offered by these intricate 3D topographies. Current challenges and new opportunities of emerging 3D microprinting techniques to further advance liquid super‐repellent materials are also discussed.