Watermarks, bar codes, RFID tags and holograms are all used on various products to make them harder to copy. One limitation that these things have in common, however, is that they are all added to just part of the product. Researchers from the Fraunhofer Institute for Applied Polymer Research have now developed an anti-counterfeiting measure that is applied to the entire product - fluorescing dyes. Needless to say, counterfeiters will have a much more daunting task when a whole product serves as its own authenticity label, as opposed to one small part of it.

By permeating a product with multiple dyes, manufacturers can ensure a unique combination that will be impossible to decode and copy. This is especially true due to the fact that only a few parts per billion of dye will be needed in any one item.

Fluorescing dyes are typically invisible under regular lighting, but show up when exposed to light of a certain wavelength. Just what that wavelength is depends upon the material to which the dye has been added. Properties such as the material’s pH and viscosity, for instance, can have a marked effect on what sort of light causes the dye to glow. This definitely complicates matters when it comes to authenticating a product, but that’s a good thing - the lack of one standard light that could be used on all materials will make it that much harder for counterfeiters to figure out a way around the technology.

The researchers state that the process could also be used for quality control, particularly when it comes to coatings. Certain dyes will glow only when the material has the proper chemical composition, dryness and/or thickness. Fraunhofer has already tested the system in the production of barrier sheets for organic light-emitting diodes (OLEDs) and photovoltaics.