Security Technology

NEW FEATURES: How Butterflies Could Help Protect Banknotes

An Indonesian Peacock or Swallowtail butterfly Photo: Cambridge University

While we often write about security devices that have already been introduced in banknotes, this week we launch the first part in a continuing series called “New Features” looking at features that are in development but have yet to be adopted by the industry.

In the world of banknote security, anti-counterfeit technology has to be developed at a feverish pace. To keep ahead of counterfeiters, banknote producers have to be consistently inventing and innovating new features to deter the future creation of bogus bills.

Recently, a number of security devices have been introduced that are proving to be revolutionary to the banknote industry. From the new US $100 bill’s 3D Liberty Bell, to Bermuda’s Optiks thread on its $2 bill, to Fortress Paper’s see-through window, banknote makers across the globe show that high-tech security features are the key to a secure banknote.

Teams of researchers and industry professionals are at the helm of developing these new technologies, but sometimes the idea for a security feature comes from an unexpected source – such as butterflies.

Research conducted by scientists at the University of Cambridge found distinctive iridescent patterns on the Indonesian Peacock Swallowtail butterfly that could – with some work – be reproduced as a near-impossible-to-copy security device for banknotes.

The wings of the Swallowtail have an intricate, multi-layered, microscopic makeup that produce intense depth and colour, and it is this multiplicity of layers (which look a little like the inside of an egg carton) that may open the doors to new security technology in banknotes.

Long a mystery to scientists, a butterfly’s colours are produced by light bouncing off microscopic structures on the insects’ wings instead of relying on pigment. The researchers at Cambridge were one of the first teams to devise a method of reproducing these intense colours and patterns.

Using a combination of nanofabrication procedures (recreating things on an miniscule atomic level) the Cambridge scientists made structurally identical copies of the butterfly scales, and these copies produced the same vivid colours as the butterflies’ wings.

So what does all this have to do with banknotes?

The idea is that now that scientists understand how to reproduce these colours and patterns on a microscopic level, they can apply this knowledge to banknotes to create specialized security features that will not only mimic the vividness of the colours and the intricacies of the patters, but also be near impossible to copy.

“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,” says Mathias Kolle, one of the lead researchers for the Cambridge study. “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.”

Though the research is complete, and the findings have been published in Nature Nanotechnology Journal, there is no word yet on whether security paper makers have taken the next step to begin applying this research to security papers such as banknotes and passports.

Science Daily: “From Butterflies’ Wings to Banknotes: How Nature’s Colours Could Cut Bank Fraud”
TG Daily: “Butterflies’ Wings Could Cut Bank Fraud”
The Telegraph UK: “Scientists Use Butterflies In Fight Against Banknote Forgery”


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  1. [...] dots are a discovery of nanotechnology (much like the recent research on butterfly mimicry as a security device) and are showing how the most miniscule elements are leading the way in security [...]

    Posted by Fortress Paper Ltd., the world leader in banknote & security papers, supplies banknotes paper to central banks and official document paper to governments and companies around the world. | July 21, 2010, 8:14 am

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