Slashdot Mirror
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."
Does that mean getting rid of waste heat is going to be even more important?
What's the efficiency like?
I wonder if such a technology could be used in artificially enhancing the muscles of a person to make a super-human, or super-soldier. The chemistry can't be that complex, so I'm sure it's possible through bio-chemical engineering. I'd bet $100 that the US and others have done it before.
Sig: I stole this sig.
Could be interesting. But what's the energy conversion efficiency like?
Have gnu, will travel.
On top of the power efficiency I'm also wondering how many times a muscle can be used before it gets too damaged.
Ah. Excellent, I have been intentionally not developing real muscles for years so I would have room for the artificial ones.
Who's sorry now dad?!
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.
Yam-like? Or is that just bad keming?
I've been watching athletes do the long jump without a pole for many, many years.
Could we run a belt made out of this stuff over a pulley system and apply a temperature differential along its length and get a motor? It's unlikely to be efficient as long as it's temperature driven, but what if the filler material is instead responsive to electricity?
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.
Maybe because of the paywall?
Contract in 25 mS - what does that mean? The time before contraction is initiated? Or is it related to shortening velocity? If so, over what distance and how liner is the contractile force? Then there's recovery time before the next contraction; the force generated per unit cross sectional area of this material (what do they exactly mean by "size"); efficiency and heat dissipation. As with all these hyped technology claims that purport to mimic biological systems there's an embarrassing lack of detail. And optimistic expectations for attracting venture capital I imagine. I'm very skeptical this would compete with mammalian or avian skeletal muscle on any number of important functional parameters. If it did and it was mine, I would be shouting the numbers from the rooftops.
This seems to have the same problem as shape-memory alloys. Those change shape quickly when heated above their transition temperature, but the amount of energy you have to put in is far more than you get out. Then they have to cool down before they can be cycled again. Power to weight ratio is good, but energy to weight ratio is poor because the cycle time is slow.
Probably not all that useful as a general actuator.
Also important and that no one has mentioned yet is the contraction ratio. The muscle does no good if it can only contract 1% of it's length...
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:
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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]
Sulphur, I don't have access through the paywall to the article, but I calculate the fiber recharge time to be less than 50 milliseconds:
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"delivers 3% tensile contraction at 1200 cycles/minute"
The abstract explicitly states that they tested the carbon-nanotube fibers for up to 1-million cycles with a rep-rate of 1200 cycles/minute, so that gives us 20 Hz, so the recharge/rep time is less than 1/20th of a second = 50 milliseconds:
The article's abstract (Electrically, Chemically, and Photonically Powered Torsional and Tensile Actuation of Hybrid Carbon Nanotube Yarn Muscles) 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]
In the book they had powered armoured suits. Three types were described: Grunt, Scout and Officer, with different capabilities.
In the movie-of-the-same-name-that-was-nothing-like-the-book, that would have been an expensive special effect, so they just had cheap plastic armour.
I'm guessing that wasn't on their radar screen...