Mechanochromic response of the barbules in peacock tail feather

Peacock tail feathers exhibit diverse striking brilliancy, as the cortex in different colored barbules of the feathers contains a 2-D photonic-crystal structure. The mechanochromic response of the 2-D photonic structure in peacock feather barbules is measured for the first time, by combining an in-situ stretching device and a reflectivity measurement system. The reflectance spectra of the barbule specimen blueshifts own to stretching along its longitudinal direction. A high strain sensitivity of 5.3 nm/% is obtained for green barbules. It could be of great help in bionic design of strain sensors using 2D photonic crystal structures.