Photonic crystals (image) RMIT University Share Print E-Mail Caption These tiny hollow spheres known as photonic crystals, inspired by the bumpy surface of butterfly wings, are the innovative core of the new hydrogen sensor. Image magnified 40,000 times. Credit RMIT University Usage Restrictions Credit RMIT University 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.