Bioinspired Asymmetric Superwettable Materials: From Structural and Wettability Regulation to Liquid Manipulation and Biomedical Applications.

The precise regulation of liquids holds significant potential in diverse fields, including microfluidic chips, smart wound dressings, medical anti-fouling coatings, and seawater desalination. Conventional strategies typically focus on manipulating liquid behavior by tailoring the microstructures and chemical compositions of surfaces. However, these methods often rely on complex fabrication processes, posing challenges for practical applications. In contrast, asymmetric materials feature structurally differentiated functional domains, enabling efficient directional liquid transport and enhanced overall performance. This design paradigm shifts liquid control from a traditional passive defence to an active and precise regulation mode, offering broad application prospects. Despite these advances, research in this field remains in its early stages and requires further exploration. Inspired by natural phenomena, many studies have proposed multifunctional asymmetric design strategies. This article systematically reviews nature-inspired liquid control systems, focusing on wettability and asymmetric structures as the key mechanisms. By engineering the structure and wettability of each layer, these strategies improve liquid manipulation. Finally, their applications in key biomedical material fields such as wound dressings and hemostatic materials are summarized, along with current challenges and future perspectives.