According to the International Anti-Counterfeiting Coalition, the United States seized almost $200 million worth of knock-off goods in 2011, with untold millions more reaching shelves and back alleys across the nation. New technologies like laser-authentication of foods and polarized thread patterns on bags give us targeted solutions to the problem, but a new technology inspired by butterfly wings may have the widest—and most beautiful—application potential yet.
To understand how the anti-counterfeiting seal works, you must first learn that butterflies don’t do blue like we do. Dyes appear a certain color because of the light they absorb and the light they reflect. Unlike lollipops or blue jeans, the wings of a blue Morpho butterfly (Morpho rhetenor) get their color from structure, not chemicals. Their wings are composed of tiny scales that "selectively cancel out certain colors through wavelength interference while reflecting others." To see the effect of these tiny ridges, just look at the insect’s earthy brown, nondiffracting underside.*
Morphos use this light-play for camouflage, thermoregulation, and mating. Now, a Canadian company called Nanotech Security Corp. is perfecting the technology for use in everything from banknotes to brake pads.
The firm has developed “nano-hole arrays” that mimic the Morpho’s iridescence by creating similar, though simpler, light-diffracting structures. And they aren’t just stuck with blue. By adjusting the shape of the hole arrays, they can change the wavelengths that get diffracted and thus the colors we see.
Aside from the diffracted seal’s obvious use in designer goods and currency, the technology may be ideal for regulation of pharmaceuticals. And because the marks require no dyes or pigments, they wouldn’t even require approval from the Food and Drug Administration. So far, though, the company seems to be focusing on the financial aspect. According to Nanotech’s website, the company is currently in talks with banknote makers, security technology developers, and financial services firms around the world.
The company says counterfeiting the mark is unlikely due to the level of technology required to make it. (Of course, history has proven that every code cracks with time. North Korea has gotten so proficient at cloning our money, we toyed with the idea of halting production of the $100 bill.) In an interview with Inside Science, the Nanotech’s chief technical officer Clint Landrock explains, “I like to say it is similar to describing how an old CRT television display looks compared to a new Ultra HD LED TV. They may be showing the same thing but you would never mistake one for the other.”
I haven’t seen Nanotech’s seal yet, but I have another frame of reference for what Landrock’s talking about. I once saw a blue Morpho in person on a trip to the Peruvian rainforest. When the insect flies, the blue-brown-blue beat of its wings makes it appear and disappear like a dancer under a strobe light. And if Nanotech’s anti-counterfeiting seal can capture that electric hue even a little bit, it’ll at least make a stunning addition to anything that needs protecting.
Correction, June 12, 2013: This blog post originally and incorrectly used "refracting" and "refracted" instead of "diffracting" and "diffracted" in four places. It has been corrected throughout the post.