Stanford

The muscles of the human body are pretty amazing—they can retract on command, stretch without damage, and even heal themselves when injured. Artificial imitators have always lagged far behind in ability, but now researchers say that they are getting close to a human-made substance that's comparable.

In a new study, researchers from Stanford detail their creation of a super-stretchy, self-healing polymer that one day could be used to make artificial muscle. The rubber-like material can stretch up to 45 times its original size and bounce right back into shape, far surpassing similar materials. It can also repair nicks and tears all on its own at extremely low temperatures, a feat also not previously accomplished by other candidates for mock muscle.

Here's why that's a major breakthrough: Back in 2000, scientists showed that some rubber-like polymers could be stretched to up to three times their length and other polymers could self-heal. But so far, no one had found anything that could do both things together—which is crucial to creating artificial muscle as powerful as a human's.

The breakthrough here comes from an improvement in a chemical bonding process known as crosslinking. The polymer is made up of connected chains of linked molecules, arranged sort of like a chain-link fence. The chains are like strings joined with elastic bands where they meet and it's the way that those chains are connected that allow the material to move around. The new polymer is an improvement in the ability of those elastic bands to stretch.

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There are still shortcomings in the synthetic stuff that make it not quite measure up to the real deal. For example, the material did not stretch as well under certain conditions as in others, meaning that a robotic elbow with this fake muscle wouldn't always be as flexible as a human one.

The same lab that came up with this fake muscle has been working on artificial skin. Between the two, we're making giant steps torward creating artificial limbs that mimic the abilities of real ones.