Ever wonder how security experts manage to stay one step ahead of counterfeiters printing fake cash or forging official documents? It usually comes down to clever tech hiding in plain sight. Now, researchers have developed a groundbreaking material that takes high-tech security to a whole new level by making anti-counterfeit markings completely invisible to the human eye.
Enter davyne, the game changer
The breakthrough comes from the Intelligent Materials Chemistry Group at the University of Turku in Finland, alongside collaborators from Aalto University, the National Institute of Chemical Physics and Biophysics in Tallinn, Estonia, and the University of Lyon in France. Published in the journal Angewandte Chemie, their latest discovery focuses on a synthetic material called davyne.
The accidental discovery behind davyne
What makes davyne so special? It is currently the only known material that changes color exclusively in the near-infrared region. To the human eye, the material looks completely static. But when you look at it through a specialized infrared-sensitive camera or a spectrometer, a color shift suddenly appears.
Interestingly, the team stumbled onto this material during a student’s thesis project. The project was studying hackmanite, a mineral that normally changes from white to pink or violet under UV light. Hackmanite reverts to its previous color if exposed to white light for a period of time or when it is heated to 100°C. However, when the student substituted calcium for sodium in the material, it turned yellow instead.
As the researchers investigated further, they noticed some samples didn’t change color visibly at all. Instead, a similar color shift was occurring strictly in the invisible, near-infrared spectrum. That active near-infrared material turned out to be davyne, a member of the cancrinite mineral family produced as a by-product of calcium hackmanite synthesis.
Tunnels, machine learning and pure chemistry
While calcium hackmanite and davyne share the exact same chemical formula, their atomic structures are different. Instead of the cavities typical of hackmanite, davyne features long, empty tunnels. Despite these structural differences, Principal Investigator Professor Mika Lastusaari and his team proved that davyne’s color-changing mechanism works similarly to hackmanite, caused by an electron transfer to a structural vacancy.
Synthesizing pure davyne wasn’t easy, as the chemical equilibrium naturally favored making calcium hackmanite. To solve this, the team partnered with materials engineering researchers and used machine learning methods to optimize the manufacturing process until they produced pure davyne.
A security feature you can turn on and off
How would this actually protect money or passports? According to Professor Mika Lastusaari from the University of Turku, davyne’s real superpower is that its near-infrared activity can be switched on and off. Lastusaari also noted that unlike traditional tags, the marking can be activated so it is visible for inspection, and then returned to an invisible state.
To prove its real-world practicality, the team tested davyne using an inexpensive camera with its color filters removed, allowing its silicon chip to pick up the specific wavelength range. When adjusted, the camera easily detected davyne’s hidden color changes under infrared light.
By inserting davyne into banknotes, passports, official documents and consumer products, authorities could soon have a simple, affordable and effective way to spot fakes. Counterfeiters wouldn’t even know what to look for, making illegal duplication exponentially harder.
Sources: Interesting Engineering, EurekAlert!