Hydrogel Muscle (IMAGE) Massachusetts Institute of Technology Caption A mechanically-trained artificial muscle resists damage (crack) propagation using aligned nanofibrils, a similar fatigue-resistant mechanism as in skeleton muscles. Credit Image: Ji Liu, Shaoting Lin, and Xinyue Liu Usage Restrictions Images are made available to non-commercial entities, press and the general public under a Creative Commons Attribution Non-Commercial No Derivatives license. You may not alter the images provided, other than to crop them to size. A credit line must be used when reproducing images. 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.