Time-lapse photo series of hydrogel (IMAGE) Delft University of Technology Caption Time-lapse photo series of a hydrogel with fuel added (middle row) compared with a control hydrogel to which nothing has been added (top row), over a three-week period (504 hours). The bottom row shows a hydrogel that changes shape independently when two different types of fuel are added. Credit TU Delft Usage Restrictions No restrictions. License Public Domain 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.