Fabrication and performance of visible-infrared stealth material imitating butterfly wings

Inspired by porous structures of butterfly wings which generate visible light colors, biomimetic films were designed for visible-infrared compatible camouflage. The effect of butterfly wing microstructure on light reflectance was simulated by the finite difference time domain (FDTD) method. On the basis of the simulated results, biomimetic films on aluminum sheets were prepared through two-step anodizing process. Influences of anodization conditions on film structure and properties were systematically studied. The microstructure and phase composition of the prepared films were characterized by XRD and SEM/EDS. The prepared films are composed of amorphous alumina , with an ordered pore structure . The thicknesses of films are from 39 nm to 1350 nm, and the diameters of pores are about 34.70–42.06 nm. The visible-infrared camouflage performance could be tuned by adjusting anodization time, voltage, and electrolyte temperature. An ultralow infrared emissivity of 0.074 was achieved in a biomimetic film with a thickness of 99.95 nm and an average pore size of 34.70 nm. The prepared films displayed multiple visible light colors, such as indigo, green, and orange, while maintaining low infrared emissivity levels less than 0.20. Such biomimetic materials exhibit potential applications in the visible-infrared camouflage field.