Fluorescing Dyes for Counterfeit-Proofing

A brand-new process that uses fluorescent dyes is claiming to render products forgery-proof. When it comes to security features, the more complicated it is to imitate, the more secure the system.

“We add various fluorescing dyes to the entire material,” said Dr. Andreas Holländer of the Fraunhofer Institute for Applied Polymer Research IAP. “With the aid of the fluorescence, we can precisely ascertain specific characteristics, and thereby recognize if we are dealing with the original, and if the quality standards have been met.”

Beside counterfeit protection, the process also is suitable for an effective quality assurance: Here, outlines characterize well-bonded and poorly bonded coatings on a function sheet. Such sheets are used to manufacture OLEDs. (Image: Armin Okulla/Harald Holeczek)

Fluorescence can be found in certain organic dyes — irradiate them within a certain wavelength range, and they emit their own light with a greater wavelength. The type of luminosity depends on the physical and chemical properties of the materials to which the dye was applied. Various dyes react to different properties, such as pH value or viscosity. For example, a certain dye glows in a tightly interlaced resin more strongly than in one that is not as dense.

To make a product counterfeit-proof, the researchers therefore add multiple dyes to the material. “In this manner, an individualized marker emerges that is exceedingly difficult to imitate,” Holländer said.

Thanks to the slight dosing, it is virtually impossible to decode the type and quantity of the dye additives — just a few parts per billion of dye concentrates suffice to mark the material. Another advantage is that the counterfeit protection definitely cannot be removed.

“Using conventional security features, the spot with the labeling can be eliminated from the material, theoretically speaking. But that approach doesn't work with our technology since the dye permeates the entire material and itself is a component of the identification label,” he said.

Besides counterfeit protection, the process also is suitable for an effective quality assurance, such as with coatings. With the aid of various dyes, manufacturers can monitor the chemical composition, degree of dryness and the thickness of the coat during the production process.

The new technology already has passed the first practice tests. Researchers marked barrier sheets for organic light-emitting diodes (OLEDs) and photovoltaics with dyes development from the Fraunhofer Polymer Surfaces Alliance POLO. Although the process is basically ready to be used, it still must be adapted to each material. A standard solution also would be contrary to the intention of the inventor.

“One reason for the high degree of security of our technology is precisely because there are only material-specific solutions,” Holländer said.

For more information, visit: www.fraunhofer.de/en