READ

Wingin’ it

Green has always been the colour of envy—and in nanotechnology, it’s no different.
diversus devops
diversus devops
Wingin’ it
Image credit: Dr Gerd Schröeder-Turk

Humans have always turned to nature for tips, tools and #inspo.

For centuries, we’ve used plant and animal pigments to dye our clothes all the colours of the rainbow.

But some shades come easier than others.

THROW SOME SHADE

In nature, green or blue colourants are tricky to make.

Nowadays, we can create blue things in two shakes of a dog’s tail. But before synthetic dyes, plant-derived indigo was ‘blue gold’, a commodity so valuable that many people were exploited in its production.

Equally tricky to source were green dyes. Mostly, people would mix indigo with yellow pigments from saffron, turmeric and onion skins.

However the small hairstreak butterfly—like many other butterflies—has been able to avoid the chemical route altogether. To get its Grinchy hue, it simply physically mimics the wavelength of light.

View Larger

The green hairstreak butterfly uses an ingenious method to colour itself green

The green hairstreak butterfly uses an ingenious method to colour itself green

SEEING GREEN

So the dogma is light travels in waves.

Different colours correspond to different wavelengths. Wavelengths are measured by the distances between peaks and troughs in light waves.

View Larger

The distance between peaks in light waves determines what colour the light is.

The distance between peaks in light waves determines what colour the light is.

We perceive things to be certain colours because pigments absorb certain wavelengths.

My jeans are blue because they contain pigments that absorb violet, indigo, green, yellow, orange and red light but reflect blue. My shoes are black because the leather was treated with stains that absorb all colours, and my shirt is pink because it’s just a damn cute colour.

LET’S GET PHYSICAL

But colour is not always chemical. Sometimes it’s physical.

On the hairstreak’s wing, structural colouration occurs when light bounces off microscopic crystallites.

The crystallites have this crazy 3D labyrinth structure. Scientists call them gyroids.

The green hairstreak butterfly’s wing is covered in crystallites made out of this gyroid material

Video credit: Dr Gerd Schröeder-Turk
The green hairstreak butterfly’s wing is covered in crystallites made out of this gyroid material

A gyroid nanostructure network covers individual scales on the wing. Crystallites run up ridges along the scales and are crossed by ribs.

This means that each individual butterfly scale is covered by a complex but highly regular structure with evenly spaced peaks and troughs.

View Larger

The green hairstreak butterfly’s wing is covered in complex but highly regular structures

Image credit: Dr Gerd Schröeder-Turk
The green hairstreak butterfly’s wing is covered in complex but highly regular structures

Because the distances between peaks and troughs of this structure match the wavelength of green light, we see green.

THE HARD STUFF

Biological gyroid nanostructures have only been thoroughly studied quite recently. But not because scientists weren’t interested in them.

Their really, really ridiculously tiny size makes them pretty tricky to examine. Literally, a centre for ants would be a thousand times too big for them.

Another problem is that most of them are made from a thin membrane supported by water.

To try and get a glimpse of these living structures inside an electron microscope, we have to put them in a vacuum.

This goes about as well as blowing soap bubbles in outer space—in other words, not well.

Without any air to push back down on the membrane, they burst. Quickly.

But our butterfly’s gyroids are not made from membranes. Rather, they’re made from a hard material called chitin. It’s a sugar that is found in the shells of insects and crustaceans as well as in fish scales and mushrooms.

And it’s significantly easier to get a good picture of what’s under a microscope at the nanometre scale.

TINY INSIGHTS

Nanostructures are pretty much everywhere, and they’re useful for just about everything.

They make lotus leaves self-cleaning. They make gecko feet sticky. They help water striders walk on water.

We can only observe the ones that create an optical effect, but even then, they’re pretty common.

The lustrous rainbows that play on oyster shells at different angles. The vibrant hues of the (innovatively named) blue-and-yellow macaw. Or the marble berry, which might be the brightest biological material in the world.

All of these come from nano bits and bobs interfering with light.

Even among butterflies, nanostructures are common. They can create blues, greens and iridescence. Even the anti-reflection coating on near-invisible glasswing butterflies have nanostructures to thank.

Basically, the hairstreak butterfly’s gyroids are special—but not that special.

What does make it unique is that, for the first time, we’ve got a picture of how the nanostructures might form.

A global collaboration—including Murdoch University researchers—have described what looks like growing gyroids marching up from the root to the tip of wing scales.

View Larger

The progression of crystallites from small to big might offer insights as to how they form

Image credit: Dr Gerd Schröeder-Turk
The progression of crystallites from small to big might offer insights as to how they form

Like the von Trapps lined up in their matchy-matchy uniforms, the nanocrystalline structures progress from little to big.

From this snapshot, scientists can infer how nanostructures come to be.

GREEN-EYED MONSTER

All of this nano action makes scientists a little jealous.

Humans could use nanostructures for so many different and useful things.

And we do use a lot already in our everyday lives. But we’ve only been studying the things for the last few years. Nature has a tiny head start (read: 3 billion years) in evolving efficient mass production of nanostructures.

So how do butterflies frost themselves in nano bling at the bat of an ommatidia? This observation of the hairstreak’s wing is the first step in answering that question.

But surely before we know it, our clothes will be covered in self-cleaningcolour-changingclimate-controlling invisible nanostructures.

It’s not the first time humans have taken inspiration from nature. And it sure won’t be the last.

diversus devops
About the author
diversus devops
View articles

NEXT ARTICLE

We've got chemistry, let's take it to the next level!

Get the latest WA science news delivered to your inbox, every fortnight.

This field is for validation purposes and should be left unchanged.

Republish

Creative Commons Logo

Republishing our content

We want our stories to be shared and seen by as many people as possible.

Therefore, unless it says otherwise, copyright on the stories on Particle belongs to Scitech and they are published under a Creative Commons Attribution-NoDerivatives 4.0 International License.

This allows you to republish our articles online or in print for free. You just need to credit us and link to us, and you can’t edit our material or sell it separately.

Using the ‘republish’ button on our website is the easiest way to meet our guidelines.

Guidelines

You cannot edit the article.

When republishing, you have to credit our authors, ideally in the byline. You have to credit Particle with a link back to the original publication on Particle.

If you’re republishing online, you must use our pageview counter, link to us and include links from our story. Our page view counter is a small pixel-ping (invisible to the eye) that allows us to know when our content is republished. It’s a condition of our guidelines that you include our counter. If you use the ‘republish’ then you’ll capture our page counter.

If you’re republishing in print, please email us to let us so we know about it (we get very proud to see our work republished) and you must include the Particle logo next to the credits. Download logo here.

If you wish to republish all our stories, please contact us directly to discuss this opportunity.

Images

Most of the images used on Particle are copyright of the photographer who made them.

It is your responsibility to confirm that you’re licensed to republish images in our articles.

Video

All Particle videos can be accessed through YouTube under the Standard YouTube Licence.

The Standard YouTube licence

  1. This licence is ‘All Rights Reserved’, granting provisions for YouTube to display the content, and YouTube’s visitors to stream the content. This means that the content may be streamed from YouTube but specifically forbids downloading, adaptation, and redistribution, except where otherwise licensed. When uploading your content to YouTube it will automatically use the Standard YouTube licence. You can check this by clicking on Advanced Settings and looking at the dropdown box ‘License and rights ownership’.
  2. When a user is uploading a video he has license options that he can choose from. The first option is “standard YouTube License” which means that you grant the broadcasting rights to YouTube. This essentially means that your video can only be accessed from YouTube for watching purpose and cannot be reproduced or distributed in any other form without your consent.

Contact

For more information about using our content, email us: particle@scitech.org.au

Copy this HTML into your CMS
Press Ctrl+C to copy