Bionic-Art Multifunctionality of nanostructured butterfly wing surfaces
S. Zobl (1,2,), W. Salvenmoser (2), T. Schwerte (2), I.C. Gebeshuber (3), M. Schreiner (1)
Interdisciplinary Research Group:
(1) University of Innsbruck, Institute of Zoology, Innsbruck, Austria.
(2) Academy of Fine Arts, Institute for Fine Arts, Vienna, Austria.
(3) University of Technology, Institute of Applied Physics, Vienna, Austria.
Butterfly wings, especially the ones with structural colours, are much more than only attractive for human eyes. Structural colours origin from highly sophisticated nanostructures with size dimensions in the range of the wavelength of the visible light. The reflected wavelengths, due to constructive interference, correlate with the thickness of the irradiated material. The thickness of the respective nanostructures, the refractive indices (n, n(cuticle) = 1.56, n(air) = 1) and the viewing angle are relevant parameters. The colour change can be induced by changing the viewing angle as well as by artificial abrasion of the colour causing structures - this can be used as indicator, e.g., of material decomposition. The design of the structure results – besides beautiful colouration – in low friction which could be used for the functionalization of plains or boats where low friction is of interest. The coloured light weight construction can furthermore be applied in specific aircraft constructions or for medical devices where potentially environmentally hazardous chemical colours and flammable substances should be avoided. Structural colours are also more reflective than colours due to pigmentation. Thus they can be seen from afar and can be used as signal colours. These colour causing nanostructures also exhibit fabulous hydrophobic properties far better than the lotus leaf offers. It allows the butterfly to fly through highly humid rainforests even if it is raining. Wetting the wing surface with water is almost impossible. The inserted video link of the poster shows a drop of honey easily dripping off this surface. Summing up the multifunctional nanostructured butterfly surfaces have the potential to inspire various important biomimetic realizations in technology.