Power suit: Gold-plated zinc oxide nanowires (yellow), each about 3.5 micrometers tall, are grown on a flexible polymer fiber. The gold-plated nanowires brush against untreated nanowires (green), which flex and generate current. Yarn spun from the fibers could lead to fabrics that convert body movements into electric current.
Z. L. Wang and X. D. Wang, Georgia Tech
Nanowires that convert motion into current could lead to textiles that can generate power.
Georgia Tech researchers have taken an important step toward creating fabrics that could generate power from the wearer's walking, breathing, and heartbeats. The researchers, led by materials-science professor Zhong Lin Wang, have made a flexible fiber coated with zinc oxide nanowires that can convert mechanical energy into electricity. The fibers, the researchers say, should be able to harvest any kind of vibration or motion for electric current.
The zinc oxide nanowires grow vertically from the surface of the polymer fiber. When one fiber brushes against another, the nanowires flex and generate electric current. The researchers described a proof-of-concept yarn in a paper published this week in the journal Nature. They show that the output current increases by entwining multiple fibers to make the yarn.
By the researchers' calculations, a square meter of fabric made from the fibers could put out as much as 80 milliwatts--enough to power portable electronics. The development could make shirts and shoes that power iPods and medical implants, curtains that generate power when they flap in the wind, and tents that power portable electronics devices.
In 2007, Wang and his colleague the 2007 TR 35 winner Xudong Wang (no relation) built a zinc oxide nanowire array that generated direct current when exposed to ultrasonic vibrations. The piezoelectric nanowires stood on an electrically conducting substrate that acted as an electrode. The other electrode was a platinum-coated silicon plate with parallel peaks and trenches carved on its surface. (See "Nanogenerator Fueled by Vibrations.") When the ultrasonic waves pushed the electrodes together, the nanowires bent and produced current.
In the new work, the researchers have substituted the rigid, zigzag electrode with a flexible one. They convert some of the bendable fibers into electrodes by applying a thin layer of gold to them. These gold-plated fibers act as flexible electrodes.
The researchers entangle a gold-coated fiber with an uncoated fiber. When the fibers are pulled back and forth with respect to each other, the individual gold-plated nanowires push and bend the uncoated nanowires, generating current.
The flexibility of the fibers brings the idea of wearable, foldable energy sources closer to fruition, says Charles Lieber, a chemistry professor at Harvard University. The flexibility is also crucial for harvesting energy from extremely small ambient motion, says Thomas Thundat, who studies nanoscale biological sensors at Oak Ridge National Laboratory. Entwining the flexible fibers, he explains, leads to very close contact between the gold-coated and the uncoated nanowires. As a result, small motions, such as a light wind or walking movements, make the coated and uncoated nanowires brush against each other and generate current.
Researchers use a running rodent to test their device.
Researchers are experimenting with a novel nanowire material to power tiny biosensors and portable devices.
An array of zinc-oxide nanowires that generates current when vibrated with ultrasonic waves could provide a new way to power biological sensors and nanodevices.
Hopefully,this technology is being shared with the Pentagon and DARPA as they are looking for a
lightweight method of powering all the electronic equipment our troops are carrying now.
Even one could make a one-square-meter sheet of the said fabric, the amount of power (80 mW) it can generate is too small to be practically useful. A one-square-inch solar cell can generate > 200 mW power.
A twisted pair is not a "fabric"
This experiment used TWO single fibers twisted around one another. The experiment is clever, but its a long LONG way from a fabric or anything useful. Electrically connecting these hairy fibers is problematic. Making a fabric without destroying the delicate nanowires is problematic, because the nanowires are necessarily exposed so that they can be in contact. I really dont see how this concept can ever be useful or practical.
This article reminded me of an idea I had years ago, but doubted the manufacturing processes would be available for years. Perhaps this can now be done? Here's how it goes:
Couldn't a modification of this make electricity from the vibration of a magnet's molecules by making a sandwich of magnetized iron, and a thin matrix of microscopic coils and diodes? Wrap up the thin sheets of both into a cylinder so it can maintain a stronger magnetic field. Put output leads to power whatever you want. Lifetime battery?
You could call it a "free cell" or something. By experimenting with the microscopic wires & diodes in the matrix, you could adjust (at time of
manufacturing) the voltage per cell.
The higher the ambient temperature in a room, the more power this device would create. Might even cool a room down in a hot environment while at the
same time producing electricity.
Pass it on if you think it's worthwhile.
Vic Bradley
Vic@Vicshouse.com
Power from Fabrics and Brownian Motion
Shouldn't it be possible to take advantage of the evergy avaliable via Brownian Motion?
If this were to be a possibility why not create a set of curtains and place them in front of an open window. On a breezy day there would be enough wind to provide plenty of movement. Motion and energy and all of it passive. eyelet curtains
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patro7
3 Comments
very nice -- however....
I must say that this is impressive -- I have been following for a while and honestly thought that mechanical scavenging would be a few years off from the ultrasonic proof of concept. As with all nanotechnology though, I am concerned about the fabrication process and its scalability. It sounds as though this can lead to a continuous (certainly batch) process without too much heartburn -- but what do I know?
Here is the kicker -- suppose you have a power scavenging fiber; how do you interconnect? Interconnect for e-textiles has always been the long pole in the tent. On another note, I would not settle for power scavenging for the sake of personal electronics, there are much cooler things we can do here...
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dhall
1 Comment
Re: very nice -- however....
Why not cover a roof with these and let low speed wind currents provide the motion? Takes care of the wiring issue. The trick is to aggregate the output of many tiny sources, which this nanotube idea seems to provide. It could sell for a multiple of what solar panels cost per peak watt because these would provide power 24 hours per day, not just when the sun is out. Buildings have a lot of wall and roof space...
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