Testing Bacteria (IMAGE) Purdue University Caption Researchers at Purdue's Biometric Standards, Performance and Assurance Laboratory test bacteria from a vein-recognition reader, a biometric device that can authenticate a person's identity. Researchers have found that although the surfaces of some biometric devices may look more unsanitary due to visible dirt and prints, they harbor about the same amount of bacteria as a typical doorknob. Credit Purdue University photo Usage Restrictions None 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.