Researchers at the University of Illinois at Urbana-Champaign have created a bio-bot using muscles. The tiny robot can be controlled via external electrical pulses.

The bio-bot is made of a 3D printed hydrogel that acts as a backbone of the tiny robot and skeletal muscle that helps the bot walk. The team wanted to mimic the muscle-tendon-bone complex found in nature. Researchers said that using skeletal muscles in the bot makes it easy to control its movements.

"Skeletal muscles cells are very attractive because you can pace them using external signals," said Rashid Bashir, head of bioengineering at the University of Illinois and lead author of the study, according to a news release. "For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it's part of a design toolbox. We want to have different options that could be used by engineers to design these things."

Previously, Bashir and colleagues had developed a robot that used heart muscle cells. A major problem with this bot was that the heart muscles are always "on" and constantly contracted. The skeletal muscles offer more control over the system.

Researchers said that they could control the pace of the bot by simply adjusting the frequency of the electric pulses. The muscles contract faster when subjected to a higher frequency and thus, move faster.

"It's only natural that we would start from a bio-mimetic design principle, such as the native organization of the musculoskeletal system, as a jumping-off point," said graduate student Caroline Cvetkovic, co-first author of the paper.

Cvetkovic added that these bio-bots could be used as surgical robots, implants or to detect hazardous material in the environment.

Next, researchers plan on including neurons in their bio-bots that can help them control it easily. They will also refine hydrogel backbone to give the bots more flexibility.

The study is published in the journal Proceedings of the National Academy of Science. It was supported by the National Science Foundation supported this work through a Science and Technology Center.