The relationship of selective surrounding response and the nanophotonic structures of Morpho butterfly scales

This paper investigates the sensitivity of micro/nano structures in Morpho butterfly scales to surrounding media. The theory of multilayer-thin-film interference is introduced to explain the mechanism of sensitivity. Two-dimensional optical models with three different geometrical designs and similar size were constructed to authenticate the theory. The rigorous coupled-wave analysis (RCWA) technique was employed for theoretical calculation of vector diffraction. By comparing the modeling results from RCWA with the experimental results, we identified the key to sensitivity, multilayer-thin-film interference occurred over a structure composed of alternating films with high and low refractive indexes. Further, we identified the main characteristics of the scales that were relevant to sensitivity. These characteristics should be applied to designing and fabricating artificial nanostructures for highly sensitive and selective bio-inspired chemical sensors. (C) 2012 Elsevier B.V. All rights reserved.