- Butterfly wings are made from microscopic structures that reflect light.
- Researchers are mimicking these structures to make it difficult to counterfeit money or credit cards.
The colorful wings of a butterfly are made possible by microscopic structures that reflect different wavelengths of light. Click to enlarge this image.
iStockphoto
Butterflies are free, the saying goes. They’re also giving materials engineers useful hints on producing vivid colors. Today, on Engineering Works! Listen to the podcast.
The next time you see a butterfly flutter by, take a moment to notice the colors on its wings. They’re some of the most vivid colors you’ll ever see. No matter how carefully we print images of butterflies, the colors are never quite the same.
There’s a reason, and it’s an odd one. Those butterfly wing colors are not like other colors. Unlike paint or ink or most other things that produce colors, butterfly wings have no pigments. Pigments are the stuff in paint or ink that reflect light that we see as different colors. Instead, the surfaces of the wings are made up of microscopic structures that would look like the inside of egg cartons if you could see them. The way light reflects from different layers gives us butterfly wings’ intense colors.
The researchers have figured out how to assemble their own butterfly wing colors by putting together layers of material, sometimes only atoms thick.
There is a reason for this. It may give a new tool to people who need to keep forgers from making counterfeit versions of paper money or credit cards. It’s not that hard to match color pigments, but duplicating the tiny holes and bumps would be really difficult.
We’re not as colorful as a butterfly wing, so we’re going home. See you next time.
Engineering Works! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station.
Tags: Butterflies, Engineering, Materials, Money, Paper
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