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Powerful artificial muscles made from ... fishing line?


February 24, 2014

The artificial muscles can lift 100 times as much weight as human muscles of the same size (Photo: University of British Columbia)

The artificial muscles can lift 100 times as much weight as human muscles of the same size (Photo: University of British Columbia)

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Artificial muscles could find use in a wide range of applications, including prosthetic limbs, robotics, exoskeletons, or pretty much any situation in which hydraulics or electric motors just aren't a practical means of moving objects. Scientists have been working on such muscles for a number of years, using materials like vanadium dioxide, graphene, carbon nanotubes and dielectric elastomers. Now, however, some of those same scientists have discovered that very powerful artificial muscles can be made from much more down-to-earth materials – regular polymer fishing line, and metal-coated nylon sewing thread.

The research was led by The University of Texas at Dallas, but involved the input of partnering universities in Australia, South Korea, Canada, Turkey and China.

To make the muscles, the team started by attaching one end of a piece of fishing line to the tip of a power drill, with the other end hanging below it, held in place by an attached heavy weight. A piece of the thread hung with the line, joined to it along one side. As the drill was powered up and its end started spinning, the line initially responded by twisting along its length. Once it had twisted as much as it could, it then proceeded to bunch up into a series of coils, like a land-line telephone receiver cord.

The scientists then heated that coiled line with a hair dryer, causing the coils to set permanently – even once the weight was removed, the line remained coiled.

A variety of sizes of the artificial muscles, with a pencil for scale (Photo: University of Texas at Dallas)

When heat is subsequently applied to one of those lines, it will respond by coiling tighter, thus contracting like a muscle. According to a recently-published paper on the research, "Extreme twisting produces coiled muscles that can contract by 49 percent, lift loads over 100 times heavier than can human muscle of the same length and weight, and generate 5.3 kilowatts of mechanical work per kilogram [2.2 lb] of muscle weight, similar to that produced by a jet engine."

While the heat could be applied electrically (via the metal in the thread), it could also take the form of exposure to light, or a chemical reaction. This means that the muscles wouldn't necessarily require an electrical power source, and could be used for things like automatically opening and closing window shutters based on time of day or air temperature.

The paper was published on Feb. 21, in the journal Science. The following video, from Australian project partner the ARC Centre of Excellence for Electromaterials Science, illustrates the production process – it also shows how a number of the artificial muscles could be weaved together, for extra power.

Sources: University of Texas at Dallas, ARC Centre of Excellence for Electromaterials Science, University of British Columbia

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

"5.3 kilowatts of mechanical work" is not consistent. Work is energy but kilowatts is power (energy per unit time).


I refure to 'nitpick' this story! I applaud the ingenuity and outside-the-box thinking it needed. May it's worth be recognised and built on for many, many uses!

The Skud

Way cool! 5.3kw/kg!! This makes it possible to create a wearable battery-powered flapping-wing birdlike backpack (flight needs about 20kw)


Sorry nitpicker but Energy is power per unit time. A Kilowatt has no time component. Kilowatt = Power Kilowatt-Hour = Energy

Sorry to be nit picky but you started it. 8^)


Sorry Warren, close but no cigar, nitpicker had it right. Kilowatt hour is a very silly unit

Joule = energy Watt = Joules / Second = Power Watt-hour = (Joules / Second) x Seconds = energy (the time component on the top and bottom of the divisor cancel out)

The Watt-hour and the Joule are both energy. Watt is energy per unit time which is power

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