Biomimetic reconstruction of butterfly wing scale nanostructures for radiative cooling and structural coloration

Abstract

Butterfly wing scales feature tile-like arrays with ridge-lamellae hierarchical microstructures. The ridge-lamellae hierarchical microstructures of wing scales have been successfully replicated in a large scale with dimensions controlled by sputtering time. Researchers have devised various fabrication strategies including laser etching, sol-gel processes, electrochemical deposition, and molecular self-assembly to achieve biomimetic surfaces.

Questions this source addresses

• How do fabrication routes like anodic aluminum oxide templating and molecular self-assembly differ in the length scales of nanostructure they can control?
• How does template-directed self-assembly using real butterfly wings as sacrificial templates preserve the ridge-lamellae hierarchy in the final inorganic replica?
• What role do alternating high/low refractive index oxide layers (e.g. TiO2/SiO2) deposited via sol-gel processing play in reproducing structural coloration?
• Why does faithfully replicating butterfly wing scale optics require hierarchical nanostructures rather than a single length scale?