LAUSR

Smart surfaces that possess switchable wettability are highly desired for a broad range of applications. However, the realization of novel approaches enabling complete alteration of surface properties independent of chemical environment and special materials is still challenging. Herein, inspired by the air sacs of insects, we fabricate a pneumatic smart surface that possesses dual-property wetting behavior and permits fast switching between states. The pneumatic surface is based on an embedded micro-air-sac network composed of an elastomer that was fabricated via a stretching-assisted mismatch-bonding process. By simply pumping the air sacs, the surface could undergo rapid and large-amplitude topography deformation, thereby exposing one surface and hiding the other, and the dominant surface and the latent surface could be switched reversibly. As a typical example, we demonstrate a smart surface with contrasting ‘petal’ and ‘lotus’ effects that enables the on-demand capture and release of water droplets. Our pneumatic strategy demonstrates a currently underexploited platform for the development of switchable smart surfaces. Inspired by the air sacs of insects, a team in China has developed a smart surface that can deliver liquid droplets to a desired location. Wettability is a measure of a material's ability to absorb or repulse fluid on its surface. Smart materials whose wettability can be controlled have the potential to manipulate fluids at the micrometer scale. Such control can be achieved by altering the chemical composition of the surface, but this can be slow. Instead, Hong-Bo Sun and colleagues from Jilin University and co-workers have designed and fabricated a smart material in which the surface is changed using pneumatic micro-air-sacs. When a water droplet comes into contact with the inflated surface, it is captured and transferred to the desired location. Deflating the micro-air-sacs releases the droplet within a second. Smart surface with tunable properties is vital for modern intelligent applications. Here we demonstrate a novel surface that enables fast surface changing based on a bioinspired micro-air-sacs network. The pneumatic smart surface allows for rapid and large-amplitude topography deformation through pneumatic control, and permits dynamic wettability switching between dominant and latent states. A smart surface with contrastive rose-petal-like and lotus-leaf-like wetting characters is presented and utilized as a droplet manipulator for in situ capture and release of water droplets on demand.