From butterflies' wings to bank notes -- how nature's colors could cut bank fraud

May 30, 2010
The bright green wings of the P. blumei butterfly result from the mixing of the different colors of light that are reflected from different regions of the scales found on the wings of these butterflies. Credit: Mathias Kolle, University of Cambridge

Scientists have discovered a way of mimicking the stunningly bright and beautiful colours found on the wings of tropical butterflies. The findings could have important applications in the security printing industry, helping to make bank notes and credit cards harder to forge.

The striking iridescent colours displayed on beetles, butterflies and other insects have long fascinated both physicists and biologists, but mimicking nature's most colourful, eye-catching surfaces has proved elusive.

This is partly because rather than relying on pigments, these colours are produced by light bouncing off microscopic structures on the insects' wings.

Mathias Kolle, working with Professor Ullrich Steiner and Professor Jeremy Baumberg of the University of Cambridge, studied the Indonesian Peacock or Swallowtail butterfly (Papilio blumei), 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.

From butterflies' wings to bank notes -- how nature's colors could cut bank fraud
This scanning electron micrograph shows that the surface of a wing scale is covered with concavities. Credit: Mathias Kolle, University of Cambridge

Using a combination of nanofabrication procedures - including and - Kolle and his colleagues made structurally identical copies of the butterfly scales, and these copies produced the same vivid colours as the butterflies' wings.

According to Kolle: "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."

"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 ."

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 says.

Intriguingly, the butterfly may also be using its colours to encrypt itself - appearing one colour to potential mates but another colour to predators.

From butterflies' wings to bank notes -- how nature's colors could cut bank fraud
This SEM image of concavities is covered by a conformal multilayer stack of 11 alternating layers of titania and alumina. Credit: Mathias Kolle, University of Cambridge

Kolle explains: "The shiny green patches on this tropical butterfly's wing scales are a stunning example of nature's ingenuity in optical design. Seen with the right optical equipment these patches appear bright blue, but with the naked eye they appear green.

"This could explain why the butterfly has evolved this way of producing colour. If its eyes see fellow as bright blue, while predators only see green patches in a green tropical environment, then it can hide from predators at the same time as remaining visible to members of its own species."

The results are published today in Nature Nanotechnology.


Explore further: Nanoparticle technology triples the production of biogas

More information: Mathias Kolle et al, 'Mimicking the colourful wing scale structure of the Papilio blumei butterfly' is published in Nature Nanotechnology on 30 May 2010.

Related Stories

Painting by numbers

Sep 29, 2006

Professor Richard ffrench-Constant of the University of Exeter in Cornwall has worked with an international team of experts to ‘decode’ the patterns on butterflies’ wings.

How the butterflies got their spots

Feb 05, 2010

(PhysOrg.com) -- How two butterfly species have evolved exactly the same striking wing colour and pattern has intrigued biologists since Darwin's day. Now, scientists at Cambridge have found 'hotspots' in ...

Nanometric butterfly wings created

Oct 08, 2009

A team of researchers from the State University of Pennsylvania (USA) and the Universidad Autónoma de Madrid (UAM) have developed a technique to replicate biological structures, such as butterfly wings, ...

Artificial butterfly in flight and filmed (w/ Video)

May 20, 2010

A group of Japanese researchers, who publish their findings today in Bioinspiration & Biomimetics, have succeeded in building a fully functional replica model - an ornithopter - of a swallowtail butterfly, and they have f ...

Recommended for you

Nanoparticle technology triples the production of biogas

Oct 22, 2014

Researchers of the Catalan Institute of Nanoscience and Nanotechnology (ICN2), a Severo Ochoa Centre of Excellence, and the Universitat Autònoma de Barcelona (UAB) have developed the new BiogàsPlus, a technology which allows ...

Research unlocks potential of super-compound

Oct 22, 2014

Researchers at The University of Western Australia's have discovered that nano-sized fragments of graphene - sheets of pure carbon - can speed up the rate of chemical reactions.

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

JoeDuff
not rated yet May 30, 2010
How this method differs conceptually from holograms, which are commonly used for security printing?
tj10
2.3 / 5 (3) Jun 01, 2010
First of all, many kudos to the team for their great work! Impressive! The mimicking of design in nature is reaping and will certainly continue to reap huge dividends for all mankind. Thanks to the scientists who worked hard, stuck at it, and finally succeeded at copying the design of our Maker!

My only quibble with the article is the way these guys want to attribute this all to evolution. It doesn't make sense.

Here you have a bunch of scientists, pooling their ideas and intelligence, purposefully trying to figure out and copy the admittedly very amazing design they observe in the butterfly. They used intelligence, purpose, physics, design detection and imitation. The idea that this butterfly somehow evolved this amazing ability by accident even though human inventors pooling their intelligence cannot even begin to replicate it, is hard to fathom! Yet, this is what evolutionists want us to muster up the faith to believe sans evidence!
PinkElephant
5 / 5 (1) Jun 02, 2010
@tj10,

"sans evidence"?

*sigh*

Another home-schooled ignoramus, admonishing those silly scientists for all the things they know but shouldn't.

Yaaaawn...
tj10
2.3 / 5 (3) Jun 02, 2010
Well, perhaps you, PinkElephant, can illuminate us all.

I didn't see any evidence given in the article to support the claim that this evolved. None. Did you? It seems they only assume that it did. They don't know how it evolved. They don't know when it evolved. They only speculate as to why it might have evolved, but that is not evidence. Anyone can make up a story to try and justify a belief. You've gotten so used to evolutionists empty claims that you don't even notice anymore. You just fall at their feet in awe and believe whatever they conjure up.

The unintelligent, directionless, uncaring, blind forces of nature used physics and designed this state of the art self-replicating technology? Congratulations on your faith! I need more than bold claims of evolutionists to bow at Charlie's feet along with you.

Of course, I have no problem with the great work these men are doing, just their interpretation of where this technology came from. Where's the evidence?
PinkElephant
5 / 5 (1) Jun 02, 2010
Worshipping, bowing, awe, belief, faith: that's what religious simpletons do. Don't throw that sort of language at me; I'm not like you.

Here's a nice, concise, ignoramus-friendly introduction to evolution and some of the more easily-digestible evidence behind it:

http://evolution....e/evo_01

(Thanks be to the University of California at Berkeley, hallowed be its name.) The truth shall set you free. Or at least, make you a little smarter. Or at least, a little less naive. Or at a minimum, a little less delusional...