Evolution of single gyroid photonic crystals in bird feathers

Vivid, saturated structural colors are conspicuous and important features of many animals. A rich diversity of three-dimensional periodic photonic nanostructures is found in the chitinaceous exoskeletons of invertebrates. Three-dimensional photonic nanostructures have been described in bird feathers, but they are typically quasi-ordered. Here, we report bicontinuous single gyroid beta-keratin and air photonic crystal networks in the feather barbs of blue-winged leafbirds (Chloropsis cochinchinensis sensu lato), which have evolved from ancestral quasi-ordered channel-type nanostructures. Self-assembled avian photonic crystals may serve as inspiration for multifunctional applications, as they suggest efficient, alternative routes to single gyroid synthesis at optical length scales, which has been experimentally elusive.

Automated summary

Vivid structural colors are important in animals, with invertebrates having diverse three-dimensional photonic nanostructures in their exoskeletons. Bird feathers also possess photonic nanostructures, with blue-winged leafbirds having unique photonic crystal networks in their barbs. These avian photonic crystals could provide inspiration for multifunctional applications, offering efficient routes to single gyroid synthesis at optical length scales.