Anyone who has ever done body-weight exercises knows that pull-ups are pretty tough. Possibly not for a new artificial muscle developed by researchers from the Department of Mechanical Science and Engineering at the University of Illinois, though. The new muscle, which could one day be used for augmenting the strength of robots, is capable of lifting up to 12,600 times its own weight. That’s significantly better than some of the previous artificial muscle projects we’ve covered. Add in a leather jacket and Austrian accent, and we’re basically on track to create The Terminator.
“Currently, electric motors are used in everyday technologies,” Caterina Lamuta, one of the researchers on the project, told Digital Trends. “Motors are a very well-developed technology, yet they are heavy and bulky. We develop artificial muscles: these are electrically driven actuators that look like muscle fibers. They are simple and monolithic, have no moving parts, and don’t produce any noise. [For this project,] we developed a novel type of artificial muscles made of a bundle of carbon fibers, embedded into a silicone rubber matrix.”
This composite material is tightly twisted until a spontaneous coiling is obtained. The contraction of the composite coiled yarn can be induced by heating it or adding an electric current, or else swelling by solvent absorption. The performance of these carbon fibers-based muscles is particularly impressive. Not only can they lift the aforementioned 12,600 times their own weight, but they can also support up to 60 MPa of mechanical stress, and contract 25 percent of their initial length.
Compared to natural skeletal muscles, they provide 18 times higher work for the same weight. With just 0.172 V/cm of applied voltage, the authors demonstrated how a 0.4 mm diameter muscle bundle could lift half a gallon of water.
“These super-strong and lightweight muscles can be used for several applications, ranging from robotics and prosthetic and human assistive devices,” Professor Sameh Tawfic, who also worked on the project, told us. “The key is that they are made from light and commercially available materials, and they are actuated by [only a] small voltage.”
A paper describing the work, titled “Theory of the tensile actuation of fiber reinforced coiled muscles,” was recently published in the journal Smart Materials and Structures.
