Friday, November 16, 2012

Artificial "Muscles"

They might not be able to make you into Superman but newly invented super-strong, artificial muscles could bring science fiction technology to life.

Super strong robots, clothes that get warmer when it’s cold and blinds that close themselves when it’s sunny are just some of the artificial muscles’ potential uses, say the technology’s creators.

Made from nanotech yarns and infused with paraffin wax, the muscles can lift more than 100,000 times their own weight and generate 85 times more power than the same size human muscle.

. . . Described in a study published online in the journal Science, the new artificial muscles are made by infusing the twisted yarn made of carbon nanotubes with a volume-changing 'guest,' such as the paraffin wax used for candle.

Heating the wax-filled yarn, either electrically or using a flash of light, causes the wax to expand, the yarn volume to increase, and the yarn length to contract.

The muscle contraction - also called actuation - can be ultrafast, occurring in 25-thousandths of a second.

The contractions could also generate a power density of 4.2 kW/kg - four times the power-to-weight ratio of common internal combustion engines, researchers showed.

Dr Baughman said the muscles were highly twisted to produce coiling, as with the coiling of a rubber band of a rubber-band-powered model airplane.

The wax-filled yarn untwists when heated electrically or by a pulse of light and its rotation reverses when heating is stopped and the yarn cools.

Attach a paddle and it will rotate to an average speed of 11,500 revolutions per minute for more than 2 million reversible cycles.

'Pound-per-pound, the generated torque is slightly higher than obtained for large electric motors,' Dr Baughman said.

The material - which can be woven, sewn, braided and knotted - can also be used in intelligent self powered materials and clothes.

Dr Baughman said clothes made of the yarn could become warmer in response to temperature change or provide increased protection in presence of chemicals.

Other potential uses of the material - which can be used in temperatures up 1000 C above the melting point of steel - also included regulating flow valves in response to chemicals and adjusting window blind openings in response to ambient temperature, he said.

Dr Baughman said the next challenge was increasing the scale of the technology.

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