Invisible QR Codes May Solve Counterfeiting Problem

South Dakota researchers have discovered a way to create invisible quick response codes, which may be a big help to discourage counterfeiting. Yes, it’s now possible to create QR codes that cannot be seen by the naked eye. How?

These invisible QR codes are made from nanoparticles of green and blue fluorescent ink that can only be seen under near-infrared laser light. These nanoparticles absorb photons at a non-visible wavelength then emit them in a visible wavelength. This process is called upconversion. And only when you have held the QR code under laser light and it becomes visible can you scan it in the traditional manner, using your smartphone.

This new technique was developed by researchers from the South Dakota School of Mines and Technology and the University of South Dakota specifically as a means of authentication. Because these invisible codes are complex and because they can have additional security features — like a specific concentration of nanoparticles or a different intensity for the upconverting light — they are hard to replicate. Also, the researchers said that they can take the security level from covert to forensic by just adding a microscopic message into the code in a different colored upconverting ink, requiring a microscope to read the uconverted code.

These codes will therefore be great when printed on banknotes, bills and other goods that can be counterfeited easily. In fact, the researchers believe that these invisible codes can be printed on virtually any solid surface. An invisible code can be added to any of these objects without altering their physical appearance.

The researchers first generated a typical QR code using an online QR code generator then converted the code into a file that’s suitable for printing via an aerosol jet printer. The process took them 90 minutes, but this can be reduced to 15 minutes if done commercially or if mass printed.