Superstrong Artificial Muscles and More From New Nanotube Material

Sheets of carbon nanotubes could make strong, stretchy artificial muscles with amazing properties

3 min read

19 March 2009—A revolutionary new material, light as air yet stronger than steel, could be used to make artificial muscles for robotic explorers operating on the broiling plains of Venus or the ice sheets of Europa, scientists say. The material could also be used for more down-to-earth applications, such as improving solar cells or organic LED displays, powering industrial robots, or reinforcing airplane fuselages.

The material, described in the 20 March issue of Science, is an aerogel—a porous, low-density solid—made from carbon nanotubes, and it has an eye-popping list of special properties. Its density is approximately 1.5 milligrams per cubic centimeter, only slightly denser than air. In one direction (along the axis of the tubes), it’s stiffer than steel. But when a voltage is applied across the aerogel [see video], repulsive forces between the nanotubes rapidly triple the material’s width, causing it to expand at 37 000 percent per second. That’s 10 times as far and 1000 times as fast as natural muscle can move, and the material does so while generating 30 times as much force as a natural muscle.

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

1 min read
A chart showing the timeline of when a transistor was invented and when it was commercialized.
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Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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