Tailoring Superwettability Through Bioinspired Reentrant Microstructures

Superwettability describes an extreme wetting regime in which a solid surface exhibits exceptional affinity for or strong repellency against fluids, including superhydro/superoleo/superaero-phobicity, superhydro/superoleo/superaero-philicity, and directional liquid transport. Recent advances in biomimetics and theoretical modeling reveal that precise and intelligent wettability regulation is governed not only by surface chemistry but, more fundamentally, by microstructural geometry. Over the past two decades, bioinspired reentrant microstructures have exhibited exceptional capability in enhancing liquid repellency and enabling high-performance directional transport through modulation of interfacial wetting physics. In this review, we provide a comprehensive summary on structure-driven superwettability, focusing on symmetric and asymmetric reentrant microstructures. We first elucidate the fundamental physical mechanisms underlying wettability regulation, followed by a critical assessment of state-of-the-art fabrication strategies, including silicon micromachining, replica molding, and advanced 3D printing. We then highlight representative applications in microreactions, oil-water separation, liquid harvesting, evaporation and desalination, and fluidic-electronic systems, and discuss emerging strategies for smart liquid manipulation enabled by stimuli-responsive reentrant microstructures. Finally, we outline key challenges and forward-looking perspectives, emphasizing artificial intelligence-assisted design, novel functional materials, scalable manufacturing, and next-generation applications of superwettable surfaces.