Robust and controllable wet attachment like tree frog toe pads attracts worldwide attention owing to potential applications in wet climbing robots, medical devices, and wearable sensors. Instead of conventional uniform pillars, nonuniform pillar arrays with features of inclination and gradients are discovered as typical structures on tree frog toe pads, whereas their effects on wet friction have been ignored. Micro‐nano in situ observation demonstrates that such a nonuniform pillar surface brings about unique multi‐dimensional self‐splitting behaviors in interfacial liquid films and contact stress distribution to enhance the wet attachment. The self‐splitting of the interfacial liquid film breaks the thick large area liquid film into an immense number of more uniform and robust tiny thin liquid bridges. Furthermore, the contact stress is redistributed by the inclined and gradient pillar array with contact stress self‐splitting, where the peak normal separating stress decreases ≈91% and lateral stress transmission increases ≈63%. Such contact stress self‐splitting further improves the liquid film self‐splitting by forming sturdy thin liquid films even under a larger load, which generates more robust capillarity with enhanced strong friction. Finally, theoretical models are built for the multi‐dimensional self‐splitting enhanced wet attachment, and applications in robotic and medical fields are performed to validate its feasibility.

Liquid transport regulation has attracted wide attention recently due to its potential applications in micro-fluidic devices, heat management, and mechanical engineering. Various liquid regulation strategies for direction guiding and speed enhancing have been developed with inspirations from nature, such as desert beetles and Nepenthes alata peristome with either gradient wettability or anisotropic structures, whereas their combined strategies for enhanced liquid regulations have barely been discussed due to the unclear coupling mechanisms. Herein, inspired by liquid transporting structure on Ligia exotica's leg, a smart flexible surface with gradient distributed and magnetized micro-cilia array is proposed to realize liquid spreading regulations in speed and direction. Different gradients and magnetic fields have been compared for liquid regulating performances, where the anisotropy ratio of liquid spreading could be enhanced from 0 on uniform surface to ∼0.3 on gradients surface, to even ∼0.6 by coupling magnetic field. The underlying liquid regulating mechanism has been established based on the mutual effects of liquid pinning and capillarity at different cilium inclined angles, cilium gap distance, and surface wettability. Finally, several liquid regulation applications are explored and offer potentials for fields of medicine and heat management.

Liquid/air accurate regulation has attracted growing attention in recent years for its diverse potential applications in bio-medicines, heat management, green energy, etc. Natural surfaces evolved innumerable hierarchical structures with exceptional functions to govern or regulate the liquid dynamic behaviors for their vital living, which have gradually been discovered as inspirations for creative design, such as fog harvesting, water fast transporting, and strong wet attachment. This review summarizes the current progress of bioinspired liquid/air regulations and their underlying mechanisms, including fast liquid/air spreading, liquid/air directional transport, and the interfacial liquid/air bridge acting forces. A fundamental understanding of both liquid/air dynamic behaviors on liquid–air–solid interfaces and their effects on the surface function has been increased with awareness of the importance of coupling effects from surface structures and material properties. The design principles and fabrication methods for bioinspired surface structure with unique liquid/air regulation are concluded, and several significant applications for electronics heat dissipation and biomedical devices are also presented. Finally, we provide new insights and future perspectives for the liquid/air regulation-based bioinspired functional materials.

Controllable transport of underwater gas bubbles is essential in various fields such as gas energy, drug delivery, and heat transfer. Although anisotropic structures are used to transport bubbles, their motion direction can only be adjusted to a limited extent because of weak structural anisotropy and small responsive deformation. Here, anisotropic bubble transport is found on microcilia surfaces of diving beetle's elytra with regular inclination and heteromorphic structure of microcilia, which have hooked tips and crescent‐shaped roots. Inspired by these, a magnetically steerable microcilia surface with large‐range inclination adjustment is proposed for highly controllable bubble transport via a heterogeneous configuration strategy. The dynamic in situ microscopic behavior shows a novel shifting phenomenon of the maximum bubble pinning position from bubble back interface for hydrophobic cilia to front interface for hydrophilic cilia under different cilium wettabilities. This shift varies the bubble shapes from unstable stretching to stable compression, thus increasing the difference in anisotropic transport by three times for hydrophilic cilia. Moreover, bioinspired heteromorphic structures can further enhance such difference by 5.5 times. Based on the proposed theory, several smart functional microcilia are designed to achieve more complex bubble manipulation, thus improving their suitability for widespread application.

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