High-Tech Invisible Ink Uses Light-Sensitive Marking in Detecting Counterfeit Goods

Counterfeit goods are currently found worldwide, quickly filling the niche wherever demand for a product exists. A previous OECD EUIPO study revealed that up to 2.5% of world trade in 2013 was in counterfeit and pirated goods, equivalent to $462 billion.

Counterfeiting has remained a serious threat to global businesses since legitimate competitors eat up market share while counterfeiters destroy consumer trust. In response, emerging technologies are developed to create solutions to fight counterfeiting.

Invisible MOF Ink

Aside from the negative economic impact, counterfeit goods also seriously threaten public health. In 2022, the U.S. Drug Enforcement Administration seized over 58.4 million fentanyl-laced fake medicines. These pills, which contain lethal doses of fentanyl, were reported to have been sold in some pharmacies.

At Sandia National Laboratories, a team of researchers developed a tool to help stop counterfeit goods. They created ink to mark authentic pill bottles and other goods, assisting companies to ensure consumer safety.

Led by materials scientist Dorina Sava Gallis, the team invented a transparent material that acts like an invisible ink. It marks authentic goods with a special pattern that appears only under certain kinds of light.

This light-sensitive marking, an optical tag, is different from other anti-counterfeit measures in that it has complex signatures that are difficult to imitate. For instance, shining a UV light on Sandia-designed ink can make one pattern visible, while a hidden pattern can only be revealed with an infrared camera. The patterns can also morph to reveal a signature animation instead of a static image.

In creating and testing the new inks, the researchers used a class of compounds called metal-organic framework (MOF), where the atoms are moved into exact positions. This precision enables the team to modify how long, how bright, and what colors the materials will shine under different conditions.

The invisible ink uses a particular recipe where only the right amounts of certain metals placed in the proper arrangement and ratios of atoms will produce a particular image. The optical tags can be authenticated in three unique ways: by detecting the pattern under light, measuring the changes of the signatures with time, and analyzing the chemicals that make up the invisible ink.

What is MOF?

Metal-organic frameworks are a relatively new class of porous, crystalline materials with a wide range of applications. These organic-inorganic hybrid materials comprise positively charged metal ions or clusters surrounded by organic 'linker' molecules. As the metal ions form nodes that bind the arms of the linkers, a repeating, cage-like structure is formed. MOFs also have hollow structures, enabling them to have an extraordinarily large internal surface area.

Unlike other porous materials, MOFs offer unique structural diversity with tunable porosity, uniform pore structures, and atomic-level structural uniformity. These properties allow researchers to gain successful control of framework functionality, porosity, and topology.