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."

Comments

Little bit hyped.

[zymano]

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.

Re:Human body uses?

[oneirophrenos]

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.

Re:One step closer to "The Terminator" . . .

[FreeFull]

Maybe because they're not biologists.

Re:Truly muscle-like, or something else?

[ortholattice]

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?

All three articles are confusing and lacking information needed to make any sort of meaningful conclusion. It seems the people writing them don't bother to think, but just string together random fact snippets that sound cool and generate hype.

One puzzle is that on the one hand, "carbon nanotubes are highly conductive", yet on the other hand need "three to five kilovolts" to contract. If the resistance were say one ohm, that would be 9 to 25 megawatts of power! A robot with 50 muscles might consume the entire output of a power plant, not to mention burn up instantly.

They also confuse the force exerted lengthwise (large) and the force exerted width wise (possibly very small, since it seems to be due to electrostatic repulsion - the videos do not show the width-wise force being measured or demonstrated).

Possibly the 1% lengthwise contraction could be amplified, to say 30% by wrapping it around a set of 30 pulleys.

Re:Close to a Space Elevator

[MichaelSmith]

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.