MIT (Massachusetts Institute of Technology) has announced an anti-counterfeiting technology, from an April 29, 2014 article by Mark Wilson for Fast Company (Note: Links have been removed),
Most of us [in the United States] know the Secret Service as the black-suited organization employed to protect the President. But in reality, the service was created toward the end of the Civil War, before Lincoln was assassinated, to crack down on counterfeit currency. Because up to a third of all money at the time was counterfeit.
Fast-forward 150 years: … the Secret Service reports that they expect counterfeiting to increase. And counterfeiting is no longer a problem for money alone. [emphasis mine] Prescription drugs are also counterfeited–with potentially deadly side effects.
As I noted in an April 28, 2014 posting (How do you know that’s extra virgin olive oil?) about a Swiss anti-counterfeiting effort involving nanoscale labels/tags, foodstuffs and petrol can also be counterfeited.
An April 13, 2014 MIT news release describes the project further,
Led by MIT chemical engineering professor Patrick Doyle and Lincoln Laboratory technical staff member Albert Swiston, the researchers have invented a new type of tiny, smartphone-readable 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 colored 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, says Doyle, the senior author of a paper describing the particles in the April 13 issue of Nature Materials. 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 colored nanocrystals, known as “rare earth upconverting nanocrystals.” [emphasis mine] These crystals are doped with elements such as ytterbium, gadolinium, erbium, and thulium, which emit visible colors when exposed to near-infrared light. By altering the ratios of these elements, the researchers can tune the crystals to emit any color in the visible spectrum.
The researchers have produced a video where they describe the counterfeiting problem and their solution in nontechnical terms,
For anyone who prefers to read their science, there’s this more technically detailed description (than the one in the video), from the MIT news release ,
To manufacture the particles, the researchers used stop-flow lithography, a technique developed previously by Doyle. This approach allows shapes to be imprinted onto parallel flowing streams of liquid monomers — chemical building blocks that can form longer chains called polymers. Wherever pulses of ultraviolet light strike the streams, a reaction is set off that forms a solid polymeric particle.
In this case, each polymer stream contains nanocrystals that emit different colors, allowing the researchers to form striped particles. So far, the researchers have created nanocrystals in nine different colors, but it should be possible to create many more, Doyle says.
Using this procedure, the researchers can generate vast quantities of unique tags. With particles that contain six stripes, there are 1 million different possible color combinations; this capacity can be exponentially enhanced by tagging products with more than one particle. For example, if the researchers created a set of 1,000 unique particles and then tagged products with any 10 of those particles, there would be 1030 possible combinations — far more than enough to tag every grain of sand on Earth.
“It’s really a massive encoding capacity,” says Bisso, who started this project while on the technical staff at Lincoln Lab. “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 use of these upconverting nanocrystals is quite clever and highly enabling,” says Jennifer Lewis, a professor of biologically inspired engineering at Harvard University who was not involved in the research. “There are several striking features of this work, namely the exponentially scaling encoding capacities and the ultralow decoding false-alarm rate.”
The microparticles could be dispersed within electronic parts or drug packaging during the manufacturing process, incorporated directly into 3-D-printed objects, or printed onto currency, the researchers say. They could also be incorporated into ink that artists could use to authenticate their artwork.
The researchers demonstrated the versatility of their approach by using two polymers with radically different material properties — one hydrophobic and one hydrophilic —to make their particles. The color readouts were the same with each, suggesting that the process could easily be adapted to many types of products that companies might want to tag with these particles, Bisso says.
“The ability to tailor the tag’s material properties without impacting the coding strategy is really powerful,” he says. “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.”
Another advantage to these particles is that they can be read without an expensive decoder like those required by most other anti-counterfeiting technologies. [emphasis mine] Using a smartphone camera equipped with a lens offering twentyfold magnification, anyone could image the particles after shining near-infrared light on them with a laser pointer. The researchers are also working on a smartphone app that would further process the images and reveal the exact composition of the particles.
Before giving a link to and a citation for the paper, I’m going to make an observations. ‘Rare earths’ the source from which these nanocrystals are derived is concerning since China, the main supplier of rare earths, is limiting the supply made available outside the country and seems intent on continuing to do so. While I appreciate the amount of rare earth needed in the laboratory is minor, should this technology be commercialized and adopted there may be a problem given that ‘rare earths’ are used extensively in smartphones, computers, etc. and that China is limiting the supply.
That said, here’s a link to and a citation for the paper,
Universal process-inert encoding architecture for polymer microparticles by Jiseok Lee, Paul W. Bisso, Rathi L. Srinivas, Jae Jung Kim, Albert J. Swiston, & Patrick S. Doyle. Nature Materials 13, 524–529 (2014) doi:10.1038/nmat3938 Published online 13 April 2014
This article is behind a paywall.