A new cyborg – part machine and part biological muscle – has taken its first steps.

University of Illinois researchers, in a report published in the Proceedings of the National Academy of Science, say their tiny new creature is the first robot that uses live muscle for power. The researchers, with funding from the National Science Foundation, have created a muscle-powered biological machine that can be controlled with an electric current.

It could lead to a new generation of biological robots, or “biobots.”

Researchers around the world have been hoping to use this type of technology for a range of applications, from building military robots to designing replacement organs.

Military robots have been on the U.S. military’s table for a while. The Defense Advanced Research Projects Agency (DARPA) has been pioneering robot research for many years, and Gen. Robert Cone, commander of the Army Training and Doctrine Command, announced in January that he was tasked with considering the reduction of brigade combat teams from 4,000 to 3,000 soldiers – and replacing the human personnel with robots.

But humanoid robots, like humans, are very complicated, and they remain elusive for now. The advances needed to build ones that can go to war are vast: They require human dexterity and movement control, not to mention quantum computing that can achieve human “intelligence.”

Some researchers believe the solution will be to combine the machine with living tissue to create Terminator-style cyborgs. It’s still the stuff of science fiction, but the tiny biobots could be a key step forward.

How does it work?

The new biobot’s design is similar to the muscle, tendon and bone systems in animals. It moves when an electrical current is applied to the muscle, causing it to contract.

Lab-grown muscle cells are grown into a strip, and 3-D printers are used to create hydrogel “backbones” that bend like joints and provide strength like bone. The strip of muscle is grafted onto the backbone, just as tendons attach muscle to bone.

The biobot’s human controller can command the robot by issuing electrical pulses that power its movement. The frequency of the pulses can be adjusted to control speed: The higher the frequency, the more muscle contractions, the faster the biobot walks.

The team has shot video of the biobot flexing its muscles to propel itself across a lab.

Earlier cyborgs

The University of Illinois team has done extensive research on blending biological tissue with machines. Its earlier cyborgs were smaller than a centimeter and combined flexible 3-D printed hydrogels with living cells.

These early biobots were powered by rats’ beating heart cells. They could walk, but researchers had limited control over them because the heart cells continually contracted, making it hard to make the robots accelerate and slow down, as well as turn on and off.

But the new generation uses skeletal muscle cells instead of heart cells, and they pave the way to create smart biobots that can be trained and programmed.

The researchers are investigating ways to further improve control over the biobots’ movements, including possibly incorporating neurons so that the robots can respond to light or chemical gradients. They are also leveraging 3-D printing to evolve engineering and design.