Drexel's BioFiber SEM Image (IMAGE) Drexel University Caption A scanning electron microscopic image of Drexel's BioFiber self-healing concrete system, showing a structural core fiber with hydrogel coating and polymer shell. Credit Drexel University Usage Restrictions none License Original 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.