Color-Changing Polymer May Signal Traumatic Brain Injuries in Soldiers, Athletes (image) American Chemical Society Share Print E-Mail Caption Microscopy images of the photonic crystals after nano-indentation at 30 mN (left), 60 mN (middle) and 90 mN (right) are shown. Credit Yang lab Usage Restrictions Please credit Yang lab for the photo. Share Print E-Mail 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.