Butterfly Biomimicry Can Curb Counterfeiting of Banknotes

butterfly money image

Image via University of Exeter

The iridescence of butterfly wings have been the source of inspiration for more energy efficient yet vivid displays, but their shine is proving useful for brightening up not just our gadgets, but the money we buy them with as well. Researchers are looking in to how biomimicry can foil the efforts of would-be forgers, using the radiant colors created by light rather than pigment. The Indonesian Peacock or Swallowtail butterfly is the subject of interest to scientists at the University of Cambridge, who are using nanofabrication processes to replicate the reflective structures onto money, making them much more difficult to counterfeit. Gizmag reports that the butterfly's wing scales are "composed of intricate, microscopic structures that resemble the inside of an egg carton. Because of their shape and the fact that they are made up of alternate layers of cuticle and air, these structures produce intense colors. Using a combination of nanofabrication procedures - including self-assembly and atomic layer deposition - [Mathias] Kolle and his colleagues made structurally identical copies of the butterfly scales, and these copies produced the same vivid colors as the butterflies' wings."

While the colors reflected back from the structures look green to the naked eye, using other optical equipment, they appear blue.

Not only can mimicking these structures be useful in security printing, allowing printers to encrypt information in optical signatures on banknotes, they could also be used on passports and other items of high value - or moving past printing, creating more efficient solar cells.
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