Credit: University of Illinois at Urbana-Campaign

Robots can be very strong, fast and enduring. However, unlike in animals, none of this strength comes from muscle, instead robots mainly rely on electrical motors and other hard and generally inflexible parts. But with all the advantages that conventional robot hardware can deliver, it still does not match the ability of muscle-powered animals to provide an accurate response to different physical environments. To address this downside of robotics, a group of researchers, led by Professor Rashid Bashir, at the University of Illinois at Urbana-Campaign developed tiny walking bio-robots powered by engineered muscle tissue.

The robot consists of a 6 mm long flexible 3D-printed backbone with two strains of muscle attached to each of its ends. The backbone has two little feet and is used both for walking and sustaining the structure. The important thing about the robot is that the muscle tissue used in it is the skeletal muscle, the one humans use to move around, which means that it can be easily turned on by administering electric impulses. Furthermore, by adjusting the frequency of the impulses, the robots’ speed can be modified.

The use of skeletal muscle allows for a better control over the robots’ movements. This significantly differs from the previous study conducted by the same group, where the researchers used heart tissue, which contracts non-stop and with a constant rate.

This technology is an important step on the way to integrating biological tissue in machines, which in some cases can be priceless. For example, muscle-powered robots are perfect for medical applications inside the body: the tissue is a perfect biodegradable material and such robots could run in a nutrient rich fluid without any additional power source. In addition, the use of muscle-powered limbs in biomimetic machine design would open hundreds of new possibilities, especially in the field of soft robotics. Imagine how much more lifelike a robotic starfish or octopus could be if powered by muscle tissue!

With the concept of a muscle-powered robot tested, the researchers are now preparing for the next step: the group envisions equipping their robots with light or chemically sensitive neurons for controlling direction of robot’s movement as well as testing new designs of the backbone to enable a wider range of motions.

The results of the study can found in PNAS in the article called “Three-dimensionally printed biological machines powered by skeletal muscle.”