A Scalable, Robust, and Bioinspired Liquid Diode for Ultrafast Unidirectional Absorption

Efficient management of biofluids on body surfaces is essential for advanced medical protection and healthcare. While conventional designs often rely solely on unidirectional penetration, our previously established model of a microfiber-covered porous substrate leverages synergistic interplay between lateral capillary forces and vertical permeation to enhance absorption kinetics by over 150-fold. However, scalable fabrication and mechanical robustness of such a structure remain challenging. Here, we present a semi-continuous manufacturing strategy based on electrostatic flocking combined with non-solvent-induced phase separation to produce a trilayered composite consisting of a micro-fiber array, a porous adhesive interlayer, and a fibrous support (MA-PA-FS). We systematically elucidate the role of each layer in guiding rapid liquid absorption and enhancing structural integrity. The optimized MA-PA-FS composite achieves ultrafast unidirectional water absorption (5 µL in 9.3 ms)-three orders of magnitude faster than a porous control surface (90.0 s)-and also effectively absorbs viscous biological fluids such as fresh porcine blood. Besides exceptional liquid absorption, the material exhibits high moisture permeability and strong mechanical durability. This study provides a scientific foundation for designing scalable, high-performance biofluid-handling interfaces, with promising potential in medical textiles, protective gear, and related health technologies.