Hamster power, Could hamsters help solve the world's energy crisis? Probably not, but a hamster wearing a power-generating jacket is doing its own small part to provide a new and renewable source of electricity.
And using the same nanotechnology, Georgia Institute of Technology researchers have also generated electrical current from a tapping finger – moving the users of BlackBerry devices, cell phones and other handhelds one step closer to powering them with their own typing.
"Using nanotechnology, we have demonstrated ways to convert even irregular biomechanical energy into electricity," said Zhong Lin Wang, a Regent's professor in the Georgia Tech School of Materials Science and Engineering. "This technology can convert any mechanical disturbance into electrical energy."
The demonstrations of harnessing biomechanical energy to produce electricity were reported February 11 in the online version of the American Chemical Society journal Nano Letters. The research was supported by the Defense Advanced Research Projects Agency (DARPA), the U.S. Department of Energy, the U.S. Air Force, and the Emory-Georgia Tech Center for Cancer Nanotechnology Excellence. |
The study demonstrates that nanogenerators – which Wang's team has been developing since 2005 – can be driven by irregular mechanical motion, such as the vibration of vocal cords, flapping of a flag in the breeze, tapping of fingers or hamsters running on exercise wheels. Scavenging such low-frequency energy from irregular motion is significant because much biomechanical energy is variable, unlike the regular mechanical motion used to generate most large-scale electricity today.
Beyond the finger-tapping and hamster-running, Wang believe his modules could be implanted into the body to harvest energy from such sources as muscle movements or pulsating blood vessels. In the body, they could be used to power nanodevices to measure blood pressure or other vital signs.
Because the devices produce alternating current, synchronizing the four generators on the hamster's back was vital to maximizing current production. Without the synchronization, current flow from one generator could cancel out the flow from another.
The research team – which also included Rusen Yang, Yong Qin, Cheng Li and Guang Zhu – solved that problem by using a substrate that was flexible in only one direction, forcing the generators to flex together. Still, there was substantial variation in the output from each generator. The differences result from variations in the amount of flexing and from inconsistencies in the hand-built devices.
"The nanogenerators have to be synchronized, with the output of all of them coordinated so the current adds up constructively," Wang noted. "Through engineering, we would expect this can be resolved in the future through improved design and more consistent manufacturing."
To ensure that the current measured was actually produced by the generators, the researchers took several precautions. For instance, they substituted carbon fibers – which are not piezoelectric – for the zinc oxide nanowires and measured no output electrical signal.
The research team encountered a number of obstacles related to its four-legged subjects. Wang's team first tried to outfit a rat with the power-generating jacket, but found that the creature wasn't very interested in running.
At the suggestion of Wang's daughter, Melissa, the researchers found that hamsters are more active creatures – but only after 11 p.m. They had to experiment with a jacket configuration that was tight enough to stay on and to wrinkle the nanogenerator substrate – but not so tight as to make the hamster uncomfortable.
"We believe this is the first demonstration of using a live animal to produce current with nanogenerators," Wang added. "This study shows that we really can harness human or animal motion to generate current." ###
Technical Contact: Zhong Lin Wang (404-894-8008); E-mail: (zhong.wang@mse.gatech.edu).
Contact: John Toon jtoon@gatech.edu 404-894-6986 Georgia Institute of Technology Research News
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