Special Reports

Using your body to charge electronics

Friday, May 07, 2010

Cell phone chargers are often referred to as power vampires.

According to some experts, 95-percent of the energy used by mobile phone chargers is wasted because people leave the charger plugged in even when they're not charging their phone.

On top of that, all the little gadgets you leave plugged in like laptops and iPods make up about 5-percent of your electricity bill.

What if we told you that you could throw away all those chargers because all you need to juice up your electronics is a pair of sneakers? Not true, you say?

Well, some scientists at Princeton say they can make it happen.

The simple act of taking a step produces enough power to charge 70 cell phones! That little fact got some scientists at Princeton thinking if the body can produce that much mechanical power, why not find a way to harness that energy and use it to power everyday electronics?

"So there's one material that can convert this mechanical energy into electrical energy and that's a piezo. Those are either naturally occurring materials or manmade and there's an effect in the material that if you stress it or compress it, it converts to electrical power," said Dr. Michael McAlpine.

For example, cigarette lighters are made of piezos. So when you press it with your thumb, it converts that mechanical energy into the electrical energy needed to ignite the flame. McAlpine said since much more mechanical energy is produced walking, the piezo could be implanted into a shoe and you could power your iPod while you walk.

The problem is piezos, or PZTs, are hard and breakable like glass, but McAlpine said he's come up with a solution using silicone. It works just like silly putty on a newspaper.

"You can actually print this material like the silly putty onto the silicone and you can actually get this energy-harvesting material onto a flexible and biocompatible material," McAlpine said.

In the above video, Erin O'Hearn demonstrated how she can create electricity. By tapping on a piece of PZT imprinted plastic, she showed how an electrical current on a computer program was forced to move up and down, all because she was tapping the plastic.

Dr. McAlpine said this material will have enormous medical benefits as well.

Think about a person with a pacemaker. Its battery needs to be replaced every 4 to 5 years and that requires the patient to undergo surgery. But if the pacemaker was lined with PZT, imprinted silicone movement of the person's own lungs could keep the battery charged.

"If you could harness the energy from your lungs that would have a huge positive impact for healthcare costs," McAlpine said.

And envision this: if you could line a shopping mall floor or sidewalks with this material, shoppers and pedestrians would create enough power with their steps to power the entire mall or even the city's public transportation.

"If you could use this instead of a battery that would definitely make things more environmentally friendly," McAlpine said.

The problems arise by getting the material on a big scale, which is very expensive, and how much use the material can endure is still not clear. So the technology is still 5-10 years away from being on the market.

The material does have a patent.

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