California researchers have developed an artificial muscle that can heal itself while generating enough electricity to charge an iPod.
Parts of the new research are already being used in Japan to generate electricity from ocean waves and it could also be used to make walking robots and develop better prosthetics.
"We've made an artificial muscle that, when you apply electricity to it, it expands more than 200 percent. The motion and energy is a lot like human muscles," quoted Qibing Pei, a scientist at the University of California, Los Angeles and study author, as saying.
Artificial muscles were introduced long ago but some get so big that they tear, developing uneven film thickness and random particles that leads to muscle failure.
Now, the researchers in California have created an artificial muscle using flexible, ever-more ubiquitous carbon nanotubes as electrodes instead of other films, often metal-based, that fail after repeated use.
In the new artificial muscle, even if an area of the carbon nanotube fails, the region around it seals itself by becoming non-conductive and stops the fault from spreading to other areas.
Pei tested the model by stabbing it with pins. If there was any other artificial muscle, it would have failed, but the self-healing muscle kept working.
"During long-term tests with the new device the actual material experiences a number of events but still worked," said Pei.
The new artificial muscle is also energy efficient.
"It conserves about 70 percent of the energy you put into it," said Pei.
As for generating electricity, when the material contracts after an expansion the rearranging of the carbon nanotubes generates a small electric current that can be captured and used to power another expansion or stored in a battery.
Japanese researchers charge batteries from ocean waves using the same idea and other scientists believe that the artificial muscle could be used to capture wind energy.
"The way he's put these carbon nanotubes together is really quite innovative. Some people want to use this to charge their batteries," said Kwang Kim, a material scientist at the University of Reno who was not involved in the research.
The research is published in the January issue of Advanced Materials.