Artificial muscles 100 times stronger than humans, could be used in prosthetic limbs, exoskeletons, robots
Three independent groups of researchers have designed powerful artificial muscles that are around 100 times stronger than ours.
The synthetic muscles are designed around coiled or coiling fibres that can stretch and contract just like their natural counterparts.
The muscle designs could have various applications — from developing smart clothing that changes in response to the weather, to prosthetic limbs and robots.
The same basic principle underpins the brawny robots developed by each research team — that coiled materials can stretch just like natural muscles.
The full findings of the studies were published in the journal Science.
Pioneering the technique was nanotech expert Ray Baughman of the University of Texas at Dallas and colleagues, who demonstrated the principle on standard household materials — sewing threads and fishing lines.
The team first showed that, after being twisted, even these basic materials can form muscle-like structures that can lift weights 100 times heavier than would be possible with human muscles of the same size.
Building on this theme, the researchers have now manufactured stronger fibres based around similarly cost-effective and familiar materials like bamboo or silk.
When coiled up and coated with a special sheath that responds to electrochemical or temperature changes, the team were able to get the muscle to contract and move in response to external triggers. Such muscle materials could be used, for example, in smart clothing — a principle that the researchers demonstrated by incorporating their muscle fibres into a textiles so that it becomes more porous in response to moisture.
“You could imagine such a textile could be more open or more insulating,” University of Illinois in Urbana-Champaign material scientist Sameh Tawfick told the New Scientist.
Putting their own twist on these coiled fabrics, material scientist Jinkai Yuan of the University of Bordeaux and his colleagues instead used polymer and stronger-than-diamond graphene to create their fibres.
In contrast, the third research group — which is led by Massachusetts Institute of Technology material scientist Mehmet Kanik — created materials that become coiled when a triggered by an external stimuli, much like a plant tendril.
To demonstrate their muscles, the researchers created a tiny artificial bicep that lifts up a small dumbbell when heat is applied to the fibre. Their fibres can lift 650 times their own weight and a resilience over thousands of cycles of expansion and contraction.
The muscle designs could have various applications — including robotic body parts, as built into the fictional cyborgs the Terminators, pictured
Natural muscles still have one key advantage over their synthetic counterparts, however — they are considerably more efficient.
Even the most advanced artificial muscle is only able to convert around three per cent of the energy that is put into it, Professor Tawfick told New Scientist.
The rest of the energy is lost, having been accidentally converted into heat.
Should engineers succeed in mitigating this problem, however, the prospective applications for artificial muscles are manifold — allowing for the creation of cheap and compact replacements for the bulky electrical motors of the present day.
Synthetic muscles could even find use in powering robotic body parts, much like those that make up the famous fictional cyborgs, the Terminators.
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