Butterfly encryption technique

Replicating the structure and colours in butterfly wings could lead to better encryption of optical signatures found on bank notes, credit cards and other items desirable to forgers.

According to Cambridge University, the colours found in butterfly wings do not rely on pigments. Instead, they are produced by light bouncing off microscopic structures on the insects’ wings.

Mathias Kolle, working with Prof Ullrich Steiner and Prof Jeremy Baumberg of Cambridge University, studied the Indonesian Peacock or Swallowtail butterfly, whose 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 colours.

Using a combination of nanofabrication procedures – including self-assembly and atomic layer deposition – Kolle and his colleagues made structurally identical copies of the butterfly scales and these copies produced the same vivid colours as the butterflies’ wings.

‘We have unlocked one of nature’s secrets and combined this knowledge with state-of-the-art nanofabrication to mimic the intricate optical designs found in nature,’ said Kolle.

‘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.’

As well as helping scientists gain a deeper understanding of the physics behind these butterflies’ colours, being able to mimic them has promising applications in security printing.

‘These artificial structures could be used to encrypt information in optical signatures on banknotes or other valuable items to protect them against forgery. 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,’ he said.