Bioinspired micro/nanostructured surfaces with wettability from design to functions

Biological surfaces provide endless inspiration for design and fabrication of smart materials. It has recently been revealed to have become a hot research area in materials and science world. For instance, the capture silk of the cribellate spider Uloborus walckenaerius collects water through a combination of multiple gradients in a periodic spindle-knot structure after rebuilding. Inspired by the roles of micro- and nanostructures in the water collecting ability of spider silk, a series of bioinspired gradient fibers has been designed by integrating fabrication methods and technologies such as dip-coating, Rayleigh instability break-up droplets, phase separation, strategies of combining electrospinning and electrospraying, and web-assembly. Based on such fabrications above, the “spindle-knot/joint” structures can be tailored to demonstrate the mechanism of multiple gradients (e.g., roughness, smooth, temperature-respond, photo-triggering, etc.,) in driving tiny water drops. A water capturing ability can be developed by the combination of “slope” and “curvature” effects on spindle-knots on bioinspired fiber, including heterostructured fibers to respond environmental humidity, temperature-responsive fiber for directional transport of droplet effectively, multi-geometric gradient fiber for the droplet target transport in a long range along as-designed bioinspired gradient fiber. Otherwise, biological surfaces such as plant leaves and butterfly wings with gradient structure features display the effect of water repellency. Smart bioinspired surfaces can be fabricated by combining machining, electrospinning, soft lithography, and nanotechnology. The gradient surfaces exhibit robust transport and controlling of microdroplets. These bioinspired gradient surfaces would be promising. Please click Additional Files below to see the full abstract