New particle 'tag' to check counterfeit goods

MIT researchers have developed new smartphone-readable microparticles that could be used to authenticate currency, electronic parts and luxury goods to help prevent counterfeiting.
Many strategies have been developed to try to label legitimate products and prevent illegal trade - but these tags are often too easy to fake, are unreliable, or cost too much to implement, researchers said.
Led by Massachusetts Institute of Technology (MIT) chemical engineering professor Patrick Doyle and Lincoln Laboratory technical staff member Albert Swiston, the researchers have invented a new type of tiny particle that they believe could be deployed to help authenticate currency, electronic parts, and luxury goods, among other products.

The particles, which are invisible to the naked eye, contain coloured stripes of nanocrystals that glow brightly when lit up with near-infrared light.
These particles can easily be manufactured and integrated into a variety of materials, and can withstand extreme temperatures, sun exposure, and heavy wear, said Doyle.
They could also be equipped with sensors that can "record" their environments - noting, for example, if a refrigerated vaccine has ever been exposed to temperatures too high or low.

The new particles are about 200 microns long and include several stripes of different coloured nanocrystals, known as "rare earth upconverting nanocrystals."

These crystals are doped with elements such as ytterbium, gadolinium, erbium, and thulium, which emit visible colours when exposed to near-infrared light.
So far, the researchers have created nanocrystals in nine different colours, but it should be possible to create many more, researchers said.
According to a 2013 United Nations report, some 2 to 5 per cent of all international trade involves counterfeit goods, researchers said.
These illicit products - which include electronics, automotive and aircraft parts, pharmaceuticals, and food - can pose safety risks and cost governments and private companies hundreds of billions of dollars annually, they said.
The finding was published in the journal Nature Materials.