Magnetic sponge can squeeze itself out

Researchers in Japan and Singapore have created a sponge that can wring itself out upon application of a magnetic field. The sponge, which is based on a network of nanomagnets, could be used as a capsule that delivers drugs to specific parts of the human body. 

First developed in the late 1990s, magnetic sponges consist of nanoparticles linked up by spring-like molecules. When the sponges absorb water they expand, and their overall magnetic properties change. As a result, they have been touted for use as sensors that can sensitively detect the presence of water.  More...

http://www.rsc.org/chemistryworld/News/2011/July/19071102.asp