Micro-muscles could be used to propel miniature robots through veins, acting as tiny muscles, controlled by electrical stimulation. Robots smaller than a grain of sand could link together, carrying out operations neither tiny robots alone, nor larger devices, could accomplish.

Micro-robots could be used for medical treatments, as well as in manufacturing.

University of Michigan researchers are developing tiny robots that could link together, forming chains of minuscule devices that could act as muscles in larger robots or within the human body.

"We are inspired by ideas of microscopic robots. They could work together and go places that have never been possible before," Michael Solomon, a professor of chemical engineering at the University of Michigan, said.

An electrical field interacts with gold plating on the micro-devices, causing the microbots to link together into a chain. The team is developing new ways of making these chains of tiny robots change shape, shifting into forms that can be used to create new materials, or heal body structures. These shapes can be directed by modifying the electrical field applied to the devices.

"The particles are like children in a playground. They do interesting things on their own, but it takes a headmaster to make them do interesting things together," Aayush Shah, a doctoral student studying under Solomon, stated in a press release.

The microbots were constructed as tiny particles, roughly one-hundredth of the width of a human hair. They were then stretched out along one axis, until they resembled tiny footballs. One side of the miniature robots was then coated with gold, in order to provide a terminal for electrical flow. When the microbots were placed in salt water, the coated sides began to attract each other, creating chains of between 50 and 60 units. This behavior became more pronounced as salt concentrations were raised by researchers. When alternating current was applied to the system, the chains began to grow, seemingly without limit. Researchers believe this property could be utilized to create and break apart chains, allowing the particles to "flex," acting like muscles in artificial systems.

Human muscles are 1,000 times more powerful than the microbots, for the same amount of material. However, they could be utilized in the creation of flexible networks of robots, to carry out a variety of tasks.

In addition to medical uses, further development could result in electronic systems able to rewire themselves quickly into novel shapes, to create new circuits that could easily be modified.

Investigators are still uncertain how or why the new phenomenon works.

"We don't fully understand why the chains extend, but we have some ideas," Benjamin Schultz, a graduate student on the research team, told the press.

Video showing the development of microbots is available on the University of Michigan YouTube channel. [https://www.youtube.com/watch?v=85uZYZjRKYI]