Bioinspired Integration of Cellular Microlattices and Asymmetric Re-Entrant Microstructures for Directional Capillary Reaction.

Self-propelled directional liquid transport enables power-free reagent delivery with minimal liquid volumes and flexible loading sites, making it a compelling platform for advanced microreaction systems. Among various strategies, bioinspired asymmetric re-entrant microstructures are particularly effective, as they harness amplified Laplace pressure gradients and capillary forces to achieve efficient directional fluid manipulation. Despite these advances, fluidic manipulation remains largely tethered to 2D surfaces, in which reaction volumes are constrained by the accessible liquid thickness, severely limiting scalability, throughput, and controllability. Inspired by the highly efficient 3D capillary confinement observed in porous natural tissues, we report an open microreaction platform that integrates cellular microlattices with asymmetric re-entrant microstructures, enabling the synergistic realization of unidirectional liquid transport and programmable reaction volume control. A programmable layer-reduction 3D printing strategy is developed to fabricate these microarchitectures with high fidelity, yielding outstanding capillary performance, including an ethanol rise height of 39.9 mm and unidirectional transport reaching 40.0 mm. The versatility of the platform is further demonstrated through physical liquid mixing and phenolphthalein-based acid-base neutralization reaction. Collectively, these results underscore the strong potential of this bioinspired strategy for realizing volume-controlled, directional capillary microreaction systems in advanced chemical and biological applications.