Tag (IMAGE) University of Copenhagen Caption The researchers tested the system by producing tags consisting of QR-codes printed on paper and sprayed with transparent ink containing various microparticles. Credit Thomas Just Sørensen Usage Restrictions The image may be used with appropriate caption or credit. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.