Carbon Fiber Artificial Muscles Can Lift 12,000 Times Their Weight

Today, most robots and machines that need to move around use motors to do it. In the future, they might use artificial muscles that work more like our own biological versions. Researchers from the Department of Mechanical Science and Engineering at the University of Illinois have created a new artificial muscle design based on coiled carbon fiber and rubber. They say this material can lift more than 12,000 times its own weight.

Coiled artificial muscles are not an entirely new idea, but other teams have used nylon fibers. The University of Illinois team believed greater strength-to-weight ratios were possible with a more versatile base material. They chose carbon fiber because of its high tensile strength and low weight. They combined carbon fiber with polydimethylsiloxane (PDMS) rubber, then coiled the material to create a muscle that can contract and relax.

Like your muscles, the artificial muscle responds to an electric current. The mechanism is quite different, though. The current heats up the rubber component and pushes the carbon fiber strands apart. That causes the coil to expand outward, thus contracting lengthwise. The researchers also found the muscles would contract when exposed to liquid hexane, but the electric current is somewhat more practical.

In the video, you can see a coiled artificial muscle with a diameter of just 0.4mm in operation. It’s lifting a half gallon of water, which weighs 12,600 times more than it does. It required just 0.172 volts per centimeter to contract. This is just a single version of the carbon fiber muscle. The artificial muscle is capable of 758 Joules of work per kilogram, which is 18 times higher than your biological muscles.

The team says it should be able to design different versions of the material that are suited to different tasks. For example, one might be able to lift less weight but do it faster. As you might notice, the video is shown at 4 times normal speed. So, the carbon fiber muscle is still rather slow compared with your own. Speeding the muscle up, even if it’s less powerful, might be a valid tradeoff.

These artificial muscles could be used in human assistive devices, like the motorized exoskeletons that help people lift heavy objects and recover from injuries. They could also find their way into robots, and if there’s anything the future needs, it’s robots that are 18 times stronger than humans. That’s no way that could go wrong.