Robotics

3D-printable synthetic muscle is three times stronger than you

Columbia University engineers have developed a soft actuator that mimics natural muscle, but is three times stronger
Columbia University engineers have developed a soft actuator that mimics natural muscle, but is three times stronger
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Columbia University engineers have developed a soft actuator that mimics natural muscle, but is three times stronger
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Columbia University engineers have developed a soft actuator that mimics natural muscle, but is three times stronger
The new synthetic muscle is electrically actuated by an embedded wire with eight volts running through it
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The new synthetic muscle is electrically actuated by an embedded wire with eight volts running through it

The classic image of a robot is one clad in a rigid metal shell, but that might not be practical in situations where man and machine will need to work together. The emerging field of soft robotics is helping to make that collaboration safer, but recreating muscle is no easy task. Now, mechanical engineers from Columbia University have developed a synthetic soft muscle that's said to be much more simple to make and run than others, and is three times stronger than the real thing.

Most soft robots are powered by pneumatic or hydraulic systems, with their movements controlled by filling and emptying bladders with liquids or gases. The problem is, that usually requires bulky external components like compressors, which prevent the systems from being shrunk down to practical sizes.

The system developed by the Columbia team is based on a natural muscle. It's made of silicone rubber matrix pocked with micro-bubbles of ethanol, giving the material low density and high elasticity. It can be 3D printed into whatever shape is needed, then electrically actuated thanks to a thin resistive wire embedded inside. Altogether, it can be made easily, cheaply and safely.

The new synthetic muscle is electrically actuated by an embedded wire with eight volts running through it
The new synthetic muscle is electrically actuated by an embedded wire with eight volts running through it

"We've been making great strides toward making robots minds, but robot bodies are still primitive," says Hod Lipson, lead researcher on the project. "This is a big piece of the puzzle and, like biology, the new actuator can be shaped and reshaped a thousand ways. We've overcome one of the final barriers to making lifelike robots."

In tests, the artificial muscle was able to expand by up to 900 percent when it was heated to 80º C (176º F) by running 8 volts through the wire. That gives it a strain density (expansion per gram) that's 15 times better than natural muscle, allowing it to lift 1,000 times its own weight.

"Our soft functional material may serve as robust soft muscle, possibly revolutionizing the way that soft robotic solutions are engineered today," says Aslan Miriyev, lead author of the study. "It can push, pull, bend, twist, and lift weight. It's the closest artificial material equivalent we have to a natural muscle."

The next steps for the team include replacing the wires inside the muscle with embedded conductive materials instead, and improving the response time and shelf life of the muscle. Further down the track, the researchers plan to experiment with controlling the system with the help of artificial intelligence.

The research was published in the journal Nature Communications, and the synthetic muscle tests can be seen in the video below.

Source: Columbia University

Soft Materials for Soft Actuators

5 comments
Martin Winlow
Are all the robots of the future going to wander about in slo-mo, then?
Ralf Biernacki
It's even worse than that, @MartinW. Pay attention to the multiplier shown in the video, from x2 to x32. This is how much the video has been speeded up---the actual movement is glacial, because it takes time for the material to heat up and then lose this heat. This response-time hurdle might turn out to be insurmountable for this design. It takes time to deliver enough heat to raise the entire muscle mass from 20ºC (std. room temp.) to 80ºC, and to distribute that heat throughout the muscle. But even if this was somehow solved (by having a very fine-grained distribution of heating elements, presumably), it would still take ages for the muscle to cool back down for the next cycle. And the amount of heat energy that has to be pumped into it is completely over the top, considering how little work it actually does. They would get much better results by dumping their muscle in the garbage, and actuating that black sausage casing with a pneumatic bladder. It wouldn't heat up, and could work much, much faster and more efficiently.
Grunchy
I don't think this is necessary, this is mostly a novelty. Robots don't need muscles that contract in order to do useful things.
AngryPenguin
@Martin @Freederick Going off the article, it looks like this is supposed to be light and efficient, not fast.
lon4
This material expands in volume, unlike natural muscle tissue, which only contracts to create motive force. See US Patent # 4,739,692, "Liquid Contractility Actuator" 1988 We never got the funding to move into production but the technique still has many applications.
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