Teaching hydrogels how to move like an earthworm

Breaking of symmetry is an important principle employed in nature to achieve directional movement in systems of various dimensional scales. The same principle can be utilized in engineered devices. Here we highlight recent work on directed motion and transport capacity of environmentally sensitive polymer gels. The directional motion of cylindrical hydrogels is driven by spatially and temporally controlled propagation of volume phase transitions along their length. This system could potentially be used in a wide variety of areas including biochemical test systems, targeted drug delivery and "soft" medical tools.