Micro muscles could propel tiny robots through your veins

One day electrically activated “muscles” can give rise to microscopic robots that are smaller than a grain of sand. The chain of particles that make up these muscles could also lead to electronics that can automatically rewire themselves as needed.

Called microbots, these microscopic robots could swim inside the human body to fight disease or crawl into bombs to defuse them, according to chemical engineers at the University of Michigan at Ann Arbor.

But building these small ‘bots and making them mobile remain two tricky obstacles. Scientists have suggested muscles made from self-assembling chains of microscopic particles could help power the microbots in the future.

When first looking at a way to design the microbots, researchers began with spherical particles made up of a combination of polystyrene, which is the plastic material used in Styrofoam. They stretched these particles in a machine until they resembled the shape of rice grains, about 0.6 microns wide and 3 microns long, and then coated one side of each particle with gold.

The glided halves of the particle were attracted to each other in salty water — the saltier the water, the stronger the connection. On their own, the particles formed short chains of overlapping pairs, averaging about 50 to 50 particles per chain. When exposed to an alternating electric current, the chains elongated and seemingly added new particles. The scientists discovered that the gold plating and alternating electric current could make the chains extend by about 36%.

By expanding and contracting, these fibers could work like small muscles, according to Sharon Glotzer, a computational physicist and chemical engineer at the University of Michigan at Ann Arbor. These findings light the way toward new reconfigurable materials made of micron-size particles that can morph and change shape in response to changes in the environment or on demand. 

Story via Discovery.