Layer (image) Penn State Caption Overall layers of the metamaterial absorber are shown. The black layer is the substrate, solid green layer is palladium, transparent blue layer is polyimide, broken green layer is the patterned layer and the transparent blue layer is again polyimide to seal and protect. Credit Bossard, Penn State Usage Restrictions Non commercial use only 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.