Movie S4 (VIDEO) Northwestern University This video is under embargo. Please login to access this video. Caption A smartphone reads a QR code printed with a fluorescent ink that is only visible under ultraviolet light. These new fluorescent inks, developed by Northwestern University scientists, would be very difficult for counterfeiters to mimic. Credit Northwestern University Usage Restrictions No restrictions 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.