Bio-inspired directional high-aspect-ratio nanopillars: fabrication and actuation

The Dynamic nature and responsive behaviour are the most attractive features of biological structures, and comprise the goals for next-generation smart materials. The nanostructured arrays provide unique topographic patterns that confer wetting, optical, and many other functions, but their actuation at the sub-micrometer scale is still a challenging goal. In this paper, we provide a simple route to fabricate ordered arrays of slender nanopillars with submicron diameters (400-500 nm) and high aspect ratios (20-40), with controllable slanted angles (60-90 degrees). Experiments reveal that the fabricated slender nanopillars are flexible so that their orientation can be dynamically manipulated in response to an external electric field, while the stiffness can prevent ground or lateral collapse. The high aspect ratio nanopillars with orientation tunability can find applications in the development of smart materials, gecko-inspired reversible adhesion, etc.