Artificial Muscles Pack a Mean Punch

sciencehabit writes "Here's a twist: Scientists have designed a flexible, yarn-like artificial muscle that can also pack a punch. It can contract in 25 milliseconds—a fraction of the time it takes to blink an eye—and can generate power 85 times as great as a similarly sized human muscle. The new muscles are made of carbon nanotubes filled with paraffin wax that can twist or stretch in response to heat or electricity. When the temperature rises, the wax melts and forces the nanotubes to contract. Such artificial muscles, the researchers say, could power smart materials, sensors, robots, and even devices inside the human body."

The article

[Anonymous Coward]

http://www.sciencemag.org/content/338/6109/928.full
I suppose that this will answer some of the questions.
Kind of makes me wonder why slashdot almost never links the REAL articles and instead just links some fancy news sites with second hand information.

Re:mechwarrior

[dunkelfalke]

Ah, triple strength myomer then.

Re: how many times a muscle can be used ...

[girlinatrainingbra]

The article's (Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles) abstract has this to say about how many times this Nanotube yarn muscle can be used:
.
We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute.
[bold text added by me to accentuate the answer, at least one million cycles demonstrated thus far]

Re:fiber recharge time less than 50 milliseconds

[Anonymous Coward]

Behind the paywall, 3% actuation requires temperature to rise from 25C to >200C. They seem to get their best work production (120 mJ/kg for input power of 6W/cm) somewhere around 1500 C. 1-5-0-0. Right around the melting point of most steels.

Not saying that's a deal breaker, but temperatures like that offer significant challenges to use as a prosthetic muscle. Probably more useful as a linear actuator in micro/nanofabrication than as 'artificial muscle.' The reason they're able to get 20 Hz operation (to 200 C) is that the 100 um diameter fibers cool really fast. if you put enough of them in place to lift macroscopically useful loads, you'll have a lot more trouble dumping waste heat.