Nature-inspired surface topography: design and function

Learning from nature has traditionally and continuously provided important insights to drive a paradigm shift in technology.In particular,recent studies show that many biological organisms exhibit spectacular surface topography such as shape,size,spatial organization,periodicity,interconnectivity,and hierarchy to endow them with the capability to adapt dynamically and responsively to a wide range of environments.More excitingly,in a broader perspective,these normally neglected topological features have the potential to fundamentally change the way of how engineering surface works,such as how fluid flows,how heat is transported,and how energy is generated,saved,and converted,to name a few.Thus,the design of nature-inspired surface topography for unique functions will spur new thinking and provide paradigm shift in the development of the new engineering surfaces.In this review,we first present a brief introduction to some insights extracted from nature.Then,we highlight recent progress in designing new surface topographies and demonstrate their applications in emerging areas including thermal-fluid transport,anti-icing,water harvesting,power generation,adhesive control,and soft robotics.Finally,we offer our perspectives on this emerging field,with the aim to stimulate new thinking on the development of next-generation of new materials and devices,and dramatically extend the boundaries of traditional engineering.

Droplet dynamics on slippery surfaces:small droplet,big impact

The dynamic interaction of droplets with slippery surfaces is essential to various industrial applications,such as anti-icing,water-repellency or water-harvesting,anti-bacterial,and phase change heat transfer.With recent progress in materials,manufacturing as well as learning from nature,the physics of droplet dynamics has been greatly enriched owing to the emergence of peculiar wetting states manifested on bio-inspired textured surfaces.This review is devoted to the discussion of the recent progress made in the authors’understanding of the dynamic interaction of small droplets with bio-inspired surfaces.Particular attention is given to droplet impact on slippery surfaces,such as superhydrophobic surfaces characterised with air-solid-liquid triple-phase interface and slippery lubricant infused porous surfaces characterised with the liquid/liquid two-phase interface.Droplet spreading,retraction,contact time,elastodynamics as well as oblique impact are systematically reviewed.Finally,the authors offer their perspectives on this important and highly multidisciplinary research area.

Achieving ultra-stable and superior electricity generation by integrating transistor-like design with lubricant armor

Extensive work have been done to harvest untapped water energy in formats of raindrops,flows,waves,and others.However,attaining stable and efficient electricity generation from these low-frequency water kinetic energies at both individual device and large-scale system level remains challenging,partially owing to the difficulty in designing a unit that possesses stable liquid and charge transfer properties,and also can be seamlessly integrated to achieve preferential collective performances without the introduction of tortuous wiring and redundant node connection with external circuit.Here,we report the design of water electricity generators featuring the combination of lubricant layer and transistor-like electrode architecture that endows enhanced electrical performances in different working environments.Such a design is scalable in manufacturing and suitable for facile integration,characterized by significant reduction in the numbers of wiring and nodes and elimination of complex interfacing problems,and represents a significant step toward large-scale,real-life applications.