Learn how to counter fake money from butterfly wings

Strange optical effects on butterfly wings can help people encrypt information on banknotes or other precious objects to prevent counterfeiting.

Blue on butterfly wings Papilio blumei . (Photo: Physicsworld)

Livescience said, when seen with the naked eye, people see green on the wings of tropical butterflies. But if you look at it with a modern optical device, those patches appear in bright blue.

' Shimmering blue patches of tropical butterflies are one of many examples of natural ingenuity,' said Mathias Kolle, a researcher at Cambridge University.

Simulation of vivid and changeable colors on the wings of butterflies and other insects is a challenge for scientists, because those colors are not produced by pigments. Instead they are created by the interaction of light with microscopic structures on the wings.

To find out the nature of the interaction between light and butterflies, Kolle and his fellow coworkers Papilio blumei . The wing scales of this butterfly are made up of tiny and complex structures. They are surrounded by interstitial layers and interlaced air. The shape of the structures and the interstitiality of the epidermis and air allow each area on the wing to create a different color.

Kolle argues that the simultaneous display of two colors can be an important evolutionary trait of butterflies.

' A butterfly sees bright blue on the wings of a fellow, while predators only see green. Trees in nature are also green, so predators cannot detect butterflies. Thus, butterflies can become invisible in the eyes of the enemy, but they still see them , 'Kolle explained.

By using artificial materials and some special nanotechnology, Kolle's team created a material that has the same surface as a butterfly's wing. Their products also create vivid colors.

' The sophisticated structures that we create can be used to encode information on banknotes or valuables to prevent counterfeiting. We still need to improve the new material, but in the future we can see the banknotes or passports displaying many colors simultaneously , 'Koll ​​asserted.

Research by Kolle group was published in Nature Nanotechnology.