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Nanotube Muscles Are Strong As Steel, Light As Air
Al writes "Scientists from the University of Texas at Dallas have created nanotube-based artificial muscles that are light as air and work even under extreme temperatures. The 'muscles' expand width-wise by about 200 percent when a voltage is applied, but are stronger than steel lengthwise. The nanotubes within the fiber naturally stick together. Applying a voltage makes them obtain a charge and repel one another. The researchers created them by stretching bundles of entangled carbon nanotubes into long threads. Several cool videos show the strange stuff in action. Some experts, including one from NASA, believe that the nanotube muscles' ability to withstand extreme heat and cold could make them suitable shape-shifting materials for future space missions."
From Article -
However, electroactive polymers generate up to eight times as much force per unit area as the nanotube sheets. "For artificial muscle, you need a large change in force coupled with a large change in length," Hunter says.
Polymer actuators also need just a few volts to contract. The ribbons, in contrast, require three to five kilovolts, which Hunter says is too high for use in humans and higher than ideal for robotics.
What wasn't apparent to me is whether these "muscles" are exerting force along the axis of their attachment points; are they pulling against the "bones" to which they're attached as they expand laterally, perpendicular to the axis of attachment?
If they're not, I don't see how these structures can be described as muscles.
Real muscles contract by myofilaments sliding past each other, shortening the overall length of the muscle. In this case no sliding past occurs, and the overall length of the nanotube "muscle" doesn't diminish, so I can't see how this technology could be used to replace actual muscles.
Maybe because they're not biologists.
No ascii art.
The fact that it is "strong as steel" and "light as air" seems to me like it could be made into a (very) big net that, when launched into orbit could capture space junk. Hopefully the fact that it stretches 200% could mean that it would have enough elasticity to absorb some of the kinetic energy of the space junk.
As long as the space junk didn't make holes in it, it would slow the junk enough so that they would fall out of orbit quickly. (Maybe the impact of a lot of junk would require periodic re-boosting of the net, I don't know.)
Another idea would be to use AEROGELS. This super lightweight material has already been proven to slow down hyper velocity objects (admittedly just particles) in the spacecraft "Stardust". The main problem with aerogels would be launching it into orbit, although it is very light the necessary volume required would be huge. However, if it could be manufactured in space then just a small amount of raw material could make a gigantic volume of the stuff.
I see the threads aren't perfect individual nanotubes, but still, good enough for a tether maybe?
Yeah I had visions of vehicles being pushed up a space elevator by peristalsis.
http://michaelsmith.id.au
why can't these scientists just devote their work to curing the common cold or the flu?
How will our immune system end up looking without a frequent visitor to give it a work out?
...as asbestos when inhaled...
Pure tungsten is about eight times as strong as mild steel -- the stuff that your car, refrigerator, and computer case are made of -- in terms of tensile strength. It's also very tolerant of high temperatures.
But because of its brittleness, it's useless as a structural material. Why do these articles always refer to strength, without describing what kind of strength that is? Tensile, compression, shear, torsional, etc.
First, we can do both. Second, we NEED ROBOTICS. The west can NOT compete economically against other nations UNLESS we give up our standard of living. The simple fact is, that America made great gains against old Europe by creating automated machinery as well as having lower costs energy coupled with EUs many nations desire to invade each other and lose their status via wars. That is what made us what we were 10 years ago (W and the neo-cons, and I am starting to think Obama and the dems, have been giving it away to china). The ONLY way to move forward is to have robotics, automated machines, and LOW COSTS ENERGY, coupled with expansion (meaning off this rock). By doing robots like this, we can send them to the moon before we get there and have them building permanent structures for us. As to biological research, that goes on.
I prefer the "u" in honour as it seems to be missing these days.
I applaud your courage and drive, yet I would abhor a future where any sovereign nation laid claim upon the moon or the stars. Before we set afoot in the galaxy, we should become an anarcho-syndicalist commune. Take it in turns to act as a sort of executive officer for the week. Naturally, all the decisions of that officer have to be ratified at a special biweekly meeting, by a simple majority in the case of purely internal affairs, but by a two-thirds majority in the case of more pressing matters.
From the article: The new actuators, on the other hand, expand by up to 200 percent but generate small forces per unit area, making them less than ideal for many applications, including robotics.
What is it with these crap materials science articles? We keep seeing articles about some new material with interesting properties, but not good enough to be useful, touted as a major breakthrough expected to show up in products Real Soon Now. This crap keeps showing up in MIT Technology Review and in Science, which used to be respected publications. It's fine to publish the materials-science results, but not with the press-release hype.
The "robot muscle" problem is well known, and many attempts have been made to address it. There's no good equivalent of biological muscles. There are several materials that are promising in theory, but not useful in practice. Electrorheological fluids have been tried, but none of them work well enough. Shape-memory alloys used to have a fan club, but they don't change shape by much, and the electrical power inputs are high for the mechanical energy out, because the power is used to heat up the material and cause a phase change.
Robots still use pneumatics, hydraulics, and electric motors, with the occasional magnetic-particle clutch.
There's some physics here too to worry about.
Stronger has two meanings. One is the breaking strength of something. e.g. when does the rope break? that's meaning #1.
Now if you are lifting an object, doing work, the more you can lift, and the faster you can left it relate to a second kind of strength.
YOu could have a carbon muscle that had a tensile breaking strength stronger than steel,that was weaker than biological muscle when it came to doing work.
Imagine all these carbon fibers in friction with each other as they jostle and slide to repel. That creates heat. every calorie of that heat is one calorie of pulling work that the muscle cannot do given an initial fixed energy input.
will it scale? don't know but it sounds great for the nanoscale where that sort of consideration is irrelevant?
Some drink at the fountain of knowledge. Others just gargle.
Maybe because they're not biologists.
Maybe they have a PhD in Creationism.
I apologize for going way off topic here, but I want to address your root cause assumptions. You apparently think that our current economic state is a result of a couple administration's worth of bad policy makers, but in fact this is something the country as a whole has been working towards since WWII.
After the second great war, this country was pretty much the only industrialized nation to survive unscathed, this much is true - and it led to artificially increasing wages, because we pretty much had a world-wide monopoly on production. This in turn led to a couple of very prosperous decades for the U.S. - the 50's and 60's. During the 70's, however, things began to turn around:
Since the 1970's, our economy has been undergoing a massive shift in the way we do business at home; rather than saving to buy, Americans now buy on credit. Our nation, by maintaining an enormous, advanced military since WWII, coupled with a decline in real wages (and therefore taxable income), has been deficit spending the entire time (actually, the U.S. has been in the red since 1830).
What you see as recent events are simply the ongoing crisis coming to a head. To borrow an apt metaphor, the U.S. sits on a house of credit cards, and there's no way go but down from this perch.
Robotics and space travel are very neat, I agree - but they aren't going to help us. There are only two ways out of this - quickly reverting back to a production economy , or declining into a pre-industrial nation and trying to make our way back from there (Obama, at least, seems to understand this; whether he can do anything about it remains to be seen).
I applaud the idea of low-cost energy, and in fact there seems to be a lot of people around the world that think free energy is currently possible, but as long as there's a profit to be made from inefficient, high cost energy, there will be no change. Thankfully, with worldwide oil production now peaking (if not already in decline), oil is going to become very expensive very soon, and will become very scarce thereafter - many of us may actually live to see the end of oil. This will drive the business world into alternative energies, but even then there'll be food shortages (it takes 10 calories of oil to get 1 calorie of food to your grocer).
And I completely disagree with expansion as a solution to anything. What we need is population reduction, and I'm so very happy that this is now happening in the U.S. (population growth is now at 95% the rate of replenishment). Once we can get the population down to the point where there's not enough people to go around, then we can begin building robotic factories.
Real muscles contract by myofilaments sliding past each other, shortening the overall length of the muscle. In this case no sliding past occurs, and the overall length of the nanotube "muscle" doesn't diminish, so I can't see how this technology could be used to replace actual muscles.
It can be used to replace muscles due to something called Poisson's ratio, which is very high for the nanotube muscle. This effectively does allow it too shorten the overall length.
The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.