Color change of Blue butterfly wing scales in an air – Vapor ambient

Abstract

Photonic crystals are periodic dielectric nanocomposites, which have photonic band gaps that forbid the propagation of light within certain frequency ranges. The optical response of such nanoarchitectures on chemical changes in the environment is determined by the spectral change of the reflected light, and depends on the composition of the ambient atmosphere and on the nanostructure characteristics. We carried out reflectance measurements on closely related Blue lycaenid butterfly males possessing so-called “pepper-pot” type photonic nanoarchitecture in their scales covering their dorsal wing surfaces. Experiments were carried out changing the concentration and nature of test vapors while monitoring the spectral variations in time. All the tests were done with the sample temperature set at, and below the room temperature. The spectral changes were found to be linear with the increasing of concentration and the signal amplitude is higher at lower temperatures. The mechanism of reflectance spectra modification is based on capillary condensation of the vapors penetrating in the nanostructure. These structures of natural origin may serve as cheap, environmentally free and biodegradable sensor elements. The study of these nanoarchitectures of biologic origin could be the source of various new bioinspired systems.