Skip to comments.How Friction May Someday Charge Your Cell Phone
Posted on 11/20/2012 1:23:10 PM PST by Red Badger
A nanogenerator made from inexpensive materials harvests mechanical energy and produces enough power to charge personal electronics.
The phenomenon that causes a painful shock when you touch metal after dragging your shoes on the carpet could someday be harnessed to charge personal electronics.
Researchers at Georgia Tech have created a device that takes advantage of static electricity to convert movementlike a phone bouncing around in your pocketinto enough power to charge a cell phone battery. It is the first demonstration that these kinds of materials have enough oomph to power personal electronics.
Excess energy produced when you walk, fidget, or even breathe can, in theory, be scavenged to power medical implants and other electronics. However, taking advantage of the energy in these small motions is challenging.
Zhong Lin Wang, a professor of materials science at Georgia Tech, has been working on the problem for several years, mostly focusing on piezoelectric materials that generate an electrical voltage under mechanical stress (see Harnessing Hamster Power with a Nanogenerator). Wang and others have amplified the piezoelectric effect by making materials structured at the nanoscale. So far, though, piezoelectric nanogenerators have not had very impressive power output.
Now Wangs group has demonstrated that a different approach may be more promising: static electricity and friction. This is the effect at work when you run a plastic comb through your hair on a dry day, and it stands on end. The Georgia Tech researchers demonstrated that this static charge phenomenon, called the triboelectric effect, can be harnessed to produce power using a type of plastic, polyethylene terephthalate, and a metal. When thin films of these materials come into contact with one another, they become charged. And when the two films are flexed, a current flows between them, which can be harnessed to charge a battery. When the two surfaces are patterned with nanoscale structures, their surface area is much greater, and so is the friction between the materialsand the power they can produce.
The Georgia Tech nanogenerator can convert 10 to 15 percent of the energy in mechanical motions into electricity, and thinner materials should be able to convert as much as 40 percent, Wang says. A fingernail-sized square of the triboelectric nanomaterial can produce eight milliwatts when flexed, enough power to run a pacemaker. A patch thats five by five centimeters can light up 600 LEDs at once, or charge a lithium-ion battery that can then power a commercial cell phone. Wangs group described these results online in the journal Nano Letters.
The choice of materials is wide, and fabricating the device is easy, says Wang. Any of about 50 common plastics, metals, and other materials can be paired to make this type of device.
Im impressed with the power density here, says Shashank Priya, director of the Center for Energy Harvesting Materials and Systems at Virginia Tech. Other smart materials havent produced enough power for practical applications, he says.
Whether the new nanogenerator will work outside the lab remains to be seen. They need to demonstrate that this can generate power from mechanical vibrations in real life, says Jiangyu Li, professor of mechanical engineering at the University of Washington in Seattle. To work in the real world, an energy scavenger will have to be able to pick up on vibrational frequencies that provide the most energy. A nanogenerator that can only pick up on low-energy mechanical vibrations would take way too long to charge a cell phone, Priya notes. Wang says he is in talks with companies about developing the energy scavenger for particular applications, and envisions it being worn on an armband.
That would be great. I recently got an android smart phone and I love it, but the battery life sucks!
I see Charlton Heston on an exercycle.
Rolex - perpetual, just not electronic.
Self-winding since 1931.
How can an entire article discuss energy harvesting walking, fidgeting, and breathing not mention once the huge potential of riding the baloney pony?
Didn't John Galt invent that first?
Years ago I bought this little wind-up contraption that you attach to your cell-phone. Crank it for a few minutes and charges the battery. Old technology, but works well enough, and cost like $5.
Had this technology been around back when I was married a mobile phone left on the coffee table would have been recharged in 5 minutes.
> Didn't John Galt invent that first?
That was my first thought, too. But Galt's motor harvested static energy from the atmosphere, not other motions that produce the static energy. Of course, one can argue that Galt's ultimate source had to be -some- motion somewhere else...
When I first read the book I dismissed the idea as fantasy (being schooled in physics long ago), but this article is a pleasing connection to reality.
Hooking up wires and a cell phone to oneself and one's partner at such a time might be considered something of a buzzkill.
Unless of course the participants are into sex with devices.
Doesn’t an aircraft traveling through an atmosphere generate a ton of static? Imagine if could harness that with a special outer surface? You could build drones that never have to return to base.
...97%....98%...oh baby, yess!!...99%....Uh, Oooh, Oh My God...100%!
The motion of the aircraft is due to burning fuel. All you're talking about is a way to recover a small percentage of the wasted energy -- it's nowhere near enough to power the craft.
What you're saying is analogous to saying that because an electric vehicle can use regenerative braking to put some of the motion energy back into the battery, that it's suddenly a "free lunch" perpetual motion machine. Sorry, it doesn't work like that.
I could see perhaps large mats of this on the ocean
to take advantage of wave/tidal action?