There's now yet another potential weapon in the war against counterfeiting. Scientists at MIT have developed tiny color-striped microparticles that could be used to verify the authenticity of currency, medication, consumer goods, or almost anything else.
The polymer particles are about 200 microns long (approximately the width of a human hair), and can be applied to a wide range of materials. Each particle is striped with up to six differently-colored bars made from nanocrystals, the color of which is determined by first doping the crystals with elements such as ytterbium, gadolinium, erbium, and thulium.
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Although the microparticles are too small to be seen by the naked eye, a smartphone equipped with a 20x magnifying lens is able to pick them out. Additionally, the colors of the nanocrystals can't be seen under natural light, but will glow when exposed to near-infrared light.
The idea is that a batch of particles could be manufactured for use on a specific type of product (a line of Prada sunglasses, for example), each one of those particles containing the same combination of colored bars unique to that product. Given that there are six bars on each particle, and it's currently possible to create those bars in any of nine colors, there are many possible color combinations that could be assigned to each particle/product. By using multiple uniquely-coded particles for one product, however, the number of possible combinations rises rapidly – MIT notes that using groups of 10 microparticles, it would be possible "to tag every grain of sand on Earth."
Merchants or consumers could then use their smartphone, equipped with a magnifying lens and near-infrared light source, to image a product's particles, and make sure that their color code is correct. Although one should never say never, it's highly doubtful that counterfeiters would be able to duplicate the particles themselves.
That said, the microparticles are reportedly easy to initially manufacture, plus they can withstand extreme temperatures, sun exposure, and heavy wear. Along with being applied to the surface of goods, they could also be integrated directly into 3D-printed items, or into inks used in the printing process.
More information is available in the video below.