Chemical engineers from the Massachusetts Institute of Technology (MIT) have invented a new type of tiny, smartphone-readable particle that could be used to help authenticate various products that are prone to counterfeiting such as electronics, pharmaceuticals and food.
The particles which are invisible to the naked eye, contain coloured stripes if nanocrystals which illuminate when lit up with near-infrared light. According to MIT professor, Patrick Doyle, the particles can be easily manufactured and integrated into a variety of materials as they have the ability to withstand extreme temperatures, sun exposure and heavy wear.
The particles and can also be equipped with sensors that can “record their environments.” For example, the sensors can identify if a refrigerated vaccine has been exposed to temperatures that are too high, or too low.
According to the researchers, the particles are around 200 microns long and include several stripes of different coloured nanocrystals which are doped with elements such as ytterbium, gadolinium, erbium, and thulium which emit visible colours when exposed to near-infrared light. By altering the ratios of these elements, the researchers can tune the crystals to emit any colour in the visible spectrum.
The researchers used stop-flow lithography to manufacture the particles which allows shapes to be imprinted onto parallel flowing streams of liquid monomers. Wherever pulses of ultraviolet light strike the streams, a reaction is set off that forms a solid polymeric particle.
Using this procedure the researchers say that they can generate vast quantities of unique tags. Particles that contain six stripes have up to one million different possible colour combinations – a number which is enhanced exponentially when products are tagged with more than one particle.
“It’s really a massive encoding capacity,” says Paul Bisso a graduate student and one of the research paper’s lead authors. “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.”
The researchers say that the mircoparticles can be dispersed within packaging during the manufacturing process to authenticate the products.
“The ability to tailor the tag’s material properties without impacting the coding strategy is really powerful,” says Bisso. “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.”
A paper describing the particles was published in the April 12 issue of science journal, Nature Materials.