April 23--Fluorescent inks are all around us, even if we don't see them.
From currency to government documents and consumer goods, items are implanted with images and other authentications that are invisible to the naked eye but glow when placed under an ultraviolet light.
Such methods are essential to stopping counterfeiting, a business that leads to losses of $650 billion globally each year, according to the International Chamber of Commerce.
But a team of Northwestern University researchers recently announced that they have developed a new kind of fluorescent ink that could further enhance such security.
While such technologies are already in use, problems arise because counterfeiters eventually can decrypt security measures, according to Chenfeng Ke, a postdoctoral fellow in chemistry at Northwestern and one of the ink's inventors.
"Once the recipe is known by the counterfeiters, the business is done," he said.
What's new about the invention spearheaded by Ke, chemistry doctoral student Xisen Hou and professor Fraser Stoddart is that they've developed a complex ink-encryption system that they say will be nearly impossible for the crooks to decipher.
"This system is simple, yet very sophisticated," Stoddart said.
In a university release announcing the work, he likened the discovery to the proprietary formulation of Coke or Pepsi.
"One could approximate their flavor using other ingredients, but it would be impossible to match the flavor exactly without a precise knowledge of the recipe," Stoddart said.
The special inks can be loaded into a standard inkjet printer cartridge, Ke said.
The sequence of the active ingredients loaded into the cartridges can be changed, he added, as can the eventual shade of the colors printed.
The methods used to reveal an authentication, be it an ultraviolet light or wiping certain chemicals on the tagged item, can also be altered, Ke said.
All the pieces are so interchangeable that users could create their own ink code that even its inventors could not decipher or replicate, he said.
The inks could one day be stamped as bar codes or QR codes on everything from currency to luxury handbags, posh cosmetics or bottles of whiskey.
The team's findings were published Wednesday in the journal Nature Communications.
Ke said the inks could be used by consumers and industry.
Authenticating via an ink stamp could be as simple as a consumer running the tag under tap water. If the tag's color changes, it's the real deal.
Stoddart credited Ke and Hou with the lion's share of the work and said he was proud of them.
Ke said the discovery came about accidentally as the team was doing other work with inks. The team has licensed the technology to a startup and filed provisional patents.
Chemistry and lab work can often appear opaque and abstract to laypeople, Hou said, but this invention helps show society the real-world benefits of such research.
"The project is a very good bridge from fundamental chemistry that leads to an application that can be used by the general public," she said. "I think that's one of the things I most appreciate."
geoffz@tribpub.com
