An artificial muscle that can heal itself and recharge an iPod at the same time? Sounds ludicrous, but researchers at the University of California at Los Angeles have developed an electricity-generating muscle that might one day be to used to create walking robots or advanced prosthetics, according to Discovery News.
Qibing Pei, a scientist at UCLA and author of the research that appeared in the January edition of Advanced Materials, said his team developed a lifelike artificial muscle by using carbon nanotubes as electrodes. Unlike other artificial muscles made with metal-based films, this muscle can expand more than 200 percent when applied with electricity, without undergoing failure. When under pressure, the carbon nanotubes have a way of shutting down and preventing the spread of failure to other areas of the muscle so it can continue to work, according to the scientists.
The muscle is also energy-efficient, conserving 70 percent of the energy put into it, the scientists said. That electrical current can be used to power other electronics like an iPhone, or can even be used to generate ocean waves. Scientists in Japan charge batteries from ocean waves using the same idea, according to Discovery.
The recently concluded K 2007 conference in Düsseldorf, Germany, featured a variety of recent advances in materials science that will change your life. No hyperbole there--just a safe prediction.
I didn't make it to the show, but I've been following the announcements on the Web site of Design News, a trade publication for mechanical engineers. The K Fair is all about plastics...but in truth, the line between plastic and metal is getting pretty blurry these days.
Indeed, companies such as DuPont are now talking about plastics climbing "the metals replacement curve." MetaFuse technology, co-developed by DuPont, Morph Technologies, Integran, and PowerMetal Technologies, combines "nanocrystalline" metals with engineering polymers to create objects with exceptionally high stiffness-to-weight ratios.
Carbon nanotubes promise to replace metal entirely in future automobiles, mobile electronics, and other products. At K 2007, companies such as Bayer and RTP showed carbon nanotube-based composite plastics. Earlier in October, Bayer announced it's building a second production facility for carbon nanotubes. The new facility's capacity is only 30 metric tons per year; Bayer and all of today's suppliers together can barely handle the demand for experimentation and prototyping, but Bayer says its "medium term" plan is to build another facility with the capacity to produce 3,000 tons per year. That's starting to become significant, I think.
Carbon-fiber composites are already strong enough to replace aluminum and steel in certain circumstances, chiefly where cost is secondary to weight or style, as in Toyota's 1/X concept, a carbon-fiber car weighing just 926 pounds, or the 2008 BMW M3--I'm planning to buy one of these next year myself.
But carbon nanotubes are so much stronger than carbon (graphite) fibers that they will likely enable entirely new design philosophies, in the same way that steel revolutionized shipbuilding, and aluminum made commercial aviation practical. We define prehistoric times in terms of materials science--the Stone Age, Bronze Age, and Iron Age--and we're on the cusp of a new age based on practical nanotechnology.
Researchers at Rensselaer Polytechnic Institute have come up with a way to detect potential structural problems with fighter planes while in flight, and in some cases repair them.
Carbon nanotubes in epoxy
(Credit: RPI)The technique, which is still experimental, involves applying an epoxy later infused with a wire grid and carbon nanotubes onto a wing or other structure. The epoxy is similar to the materials currently used to make fighter plane components. The wire grid and the nanotubes function as a communication network. Mechanics (or a computer) will shoot an electrical charge through the structure and measure how long it takes an electrical charge to go from two selected points.
If there is a crack in the structure, the crack will create electrical resistance. In that case, the signal will have to travel a longer distance to get around the crack. The extra time required to get from point A to point B serves as a signal that a potential problem exists. The picture shows carbon nanotubes randomly dispersed in an epoxy.
The cracks can also be repaired, depending on the material the wing is made of and other factors. When a crack is detected, voltage to the carbon nanotubes can be increased. This generates heat, which melts the epoxy that fills the crack in. In certain circumstances, the repaired wing will regain up to 70 percent of its original strength, according to RPI. That should keep you from plunging to your death.
The beauty of this method is that the carbon nanotubes are everywhere. The sensors are actually an integral part of the structure, which allows you to monitor any part of the structure," said Nikhil A. Koratkar, an associate professor in Rensselaer's Department of Mechanical, Aerospace & Nuclear Engineering, in a prepared statement. Koratkar was the principal investigator on the project.
A more detailed paper was published this week in Applied Physics Letters.
Nanotubes, which are stronger than steel, can also add structural integrity, depending on how they are integrated into a structure. General Motors puts multiwalled nanotubes into some car parts.
Angela Belcher at MIT (and co-founder of Cambrios Technologies) is working on a different technology for detecting flaws in metal aircraft parts. She is trying to develop genetically engineered microorganisms that will secrete proteins that will attach to specific metal alloys. Smear it on, the theory goes, and the luminescent protein will stick to areas undergoing abnormal amounts of stress.
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