Russian scientists develop invisible anti-counterfeit labels

Researchers in Russia have developed a new form of security label based on a rare earth metal technology that they suggest could be used to protect goods from counterfeiting.

The team from ITMO University and St Petersburg Academic University have used a laser to add ions of the rare-earth metal erbium to create an image on a sticker made of a silicon nanofilm. They create a lattice of holes on the film and in some of those add erbium in a defined pattern.

“When subjected to laser radiation, the holes with erbium change colour – and thus they allow us to correctly read the image,” said Dmitriy Zuev, assistant professor at ITMO's department of physics and engineering who leads the project.

The scientists say that manufacturers could use the approach as a covert way to label electronics, drugs, jewellery, and other products with invisible images that can only be seen using special equipment.

Counterfeiters would struggle to discover the format of the images, even if they know it is present, as they would have to get into the shipment system, learn to work the equipment, and master label reading methods.

The research is published in the journal Advanced Materials, and describes two different types of anti-counterfeit labels.

In one, laser writing of luminescent areas would be detected by optical microscopy as holes in the film forming the desired image.

A second type – with a higher degree of security – incorporates other fabrication steps, including the chemical etching of the erbium layer and laser writing of additional non‐luminescent holes over an initially recorded image.

"Our labels are based on erbium ion luminescence, which is characterized by several parameters: intensity, wavelength, and radiative lifetime,” explains Artem Larin, a Ph.D. student at ITMO.

“A combination of these parameters allows us to create additional layers of protection. That's why when you get the hidden image with an infrared sensor, you will also be able to read the information about the luminescence parameters. This provides an additional degree of protection,” he adds.