Color Changes upon Cooling of Lepidoptera Scales Containing Photonic Nanoarchitectures
Photonic crystal type nanoarchitectures have an important advantage over conventional displays: they do not fade under solar illumination; on the contrary, more intense illumination generates more intense color. We present a simple method based on cooling in ambient air - to observe the color change of several butterfly wings colored by various photonic nanoarchitectures. The color change can be attributed to the condensation of atmospheric humidity in the nanocavities of the photonic nanoarchitecture. The effects were investigated by controlled cooling combined with the in-situ measurement of the changes in the reflectivity spectra. For certain species the reflectivity maximum (color) has almost completely disappeared. A correlation was also found between the openness of the nanostructure and the time of the color change. Cooling experiments, using thin copper wires showed that color alteration could be limited to millimeters; this may offer a possible alternative for display technology.
Evangelos Hristoforou and D.S. Vlachos
I. Tamáska et al., "Color Changes upon Cooling of Lepidoptera Scales Containing Photonic Nanoarchitectures", Key Engineering Materials, Vol. 543, pp. 18-21, 2013