Phononic Crystals (IMAGE) The University of Hong Kong Caption The phononic crystals are made by artificially placing the acrylic posts in the special pattern. Credit The University of Hong Kong Usage Restrictions Image may only be used with appropriate caption and 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.