27th Annual Shih-I Pai Lecture at the University of Maryland with Hui Cao (2021)

Structural color originates from physical interaction of light with nanostructures. Most studies so far have focused on ordered structures which produce iridescent colors that change with viewing angle. However, nature has used extensively quasi-ordered structures to create weakly iridescent colors. An interdisciplinary team, consisting of optical physicists, material scientists, and biologists at Yale, has investigated the physical mechanism for coloration of nanostructures with short-range order in bird feather barbs. Inspired by nature, a simple technique is developed to fabricate large-scale biomimetic films which display isotropic structural color, that is amenable to potential applications in coatings, cosmetics, and textiles. In order to understand how the structural color evolves in nature, artificial selection has been conducted on a lab model butterfly to evolve the structural color of wing scales and compared to natural selection. This study reveals the physical mechanism of structural color evolution, which stands in sharp contrast to pigment color evolution.