A team of scientists led by Jon Kellar at the South Dakota School of Mines and Technology have come up with a special QR code—using nanoparticles combined with blue and green fluorescent ink—that can be used to prevent counterfeiters from getting away with passing along forged cash. The code is designed with standard computer-aided design (CAD) equipment and can be sprayed onto surfaces such as paper, plastic film, tape and glass, using an aerosol jet printer, reports the AFP. The code is invisible until illuminated under a near-infrared laser. Read the full story at Gizmodo.