Engineers from the Massachusetts Institute of Technology (MIT) have developed smartphone-readable particles that could be used to help authenticate and protect currency, luxury goods, electronic parts, and other products.
These particles are invisible to man's naked eye, but their nanocrystals, which have colored stripes, are seen when they are lit up with infrared-light. They can be applied to a wide range of materials and products, last under extreme levels of temperature, be exposed to the sun, and they are very durable. They can also keep records of the changes in their environments, for example, they can note if a refrigerated product has been exposed to temperatures that are too high or too low.
These particles are the product of the study conducted by Patrick Doyle, a chemical engineering professor and Albert Swiston, a technical staff member. The particles measure around 200 microns long and they are covered with colored nanocrystals known as "rare earth upconverting nanocrystals". These crystals are covered with erbium, gadolinium, thulium, and ytterbium to make them emit colors when they are lit up with infrared light.
The creation of these particles involved a technique called stop-flow lithography that incorporated the shapes into the streams of liquid monomers. These liquid monomers function as building blocks that improve the chains of polymers that influence the colors of the tags. This procedure allows the researchers to develop a huge amount of individually-unique tags.
"It's really a massive encoding capacity," MIT graduate student Paul Bisso stated in a news release. "You can apply different combinations of 10 particles to products from now until long past our time and you'll never get the same combination."
Possible applications of these particles include electronic parts, packaging of drugs, currency, paintings, and other luxury goods.
"The ability to tailor the tag's material properties without impacting the coding strategy is really powerful," Bisso explained in a news release. "What separates our system from other anti-counterfeiting technologies is this ability to rapidly and inexpensively tailor material properties to meet the needs of very different and challenging requirements, without impacting smartphone readout or requiring a complete redesign of the system."
Further details of this study were published in the April 15 issue of Nature Materials.
