Nature may beautify bank notes of future

Bank notes could one day be made as beautiful as butterfly wings using technology borrowed from nature.

British scientists have found a way to mimic the vivid iridescent colours of tropical butterflies, created by light bouncing off microscopic wing structures.

One application of the research could be the creation of hard-to-forge and visually striking bank notes and credit cards.

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"These artificial structures could be used to encrypt information in optical signatures on bank notes or other valuable items to protect them against forgery," said Cambridge University PhD student Mathias Kolle.

"We still need to refine our system, but in future we could see structures based on butterflies' wings shining from a 10 note or even our passports."

The Cambridge team studied the Indonesian peacock, or swallowtail, butterfly – Papilio blumei – whose eye-catching green and blue wings generate intense colours. The insect's wing scales produce an intricate surface pattern resembling the inside of an egg carton.

Mr Kolle and two professors from the university's Cavendish Laboratory made identical copies of the structures using advanced nanotechnology.

Recreating the colours of beetles, butterflies and moths has previously proved elusive because of the technical challenge of shaping materials.

Mr Kolle said one of nature's secrets had been unlocked.

"Although nature is better at self-assembly than we are, we have the advantage that we can use a wider variety of artificial, custom-made materials to optimise our optical structures."

The research is published in the journal Nature Nanotechnology.