Unlocking the Power of the Body Electric

American soldiers slogging though Afghanistan use constant radio communication, satellite navigation and night vision goggles. Today, a single grunt has capabilities and powers a battalion couldn’t call on just a couple of decades ago.

But the gizmos that give a commando godlike abilities devour power. There was a time not so long ago when all an infantryman had to carry were a weapon and ammo. Now he’s got to drag around a couple of pounds of batteries for stuff like his range finder.

Some servicemen have to lug a pack that tops 100 pounds, depending on the mission. When gear gets that heavy, the choice comes down to packing an extra AA battery or another couple of rounds for the rifle. There’s only so much weight a man can carry before he looses his effectiveness as a soldier--and in many cases, a battery can be more important than a bullet.

That is one reason so many researchers are trying to capture electricity derived directly from human bodies to power portable devices. Although much of the research has been aimed at military applications, low-end civilian uses for this technology will appear soon, perhaps even next year. And someday, the ability to self-generate power might help dramatically redesign many everyday things.

For decades, the normal movements of the human body have powered some smaller gadgets. The best example is a self-winding watch, which uses the frequent motion of the human arm to wind a spring and keep the clock mechanism moving.

Several researchers, such as Joe Paradiso, head of the responsive environments group at the Massachusetts Institute of Technology’s Media Lab, have installed tiny power generation equipment in shoes. Every step generates a burst of electricity. Properly controlled, that’s the sort of thing that could power a radio.

“The trick here is storing the electricity in some kind of battery, so that the power doesn’t stop if you’re not walking around,” Paradiso said.

Other researchers are thinking about other ways to tap the energy created by the human body. One of the most common methods is based on a well-understood principle that the difference in temperature between two objects can be converted into electricity. Advanced Power Solutions Inc. of Palm Beach, Fla., said its tiny thermoelectric generator will be used in a wristwatch that may be on the market next year. The generator creates electricity based on the difference in temperature between skin and air.

Why should anybody care about this?

“Beyond the life-and-death decisions on the battlefield, which is the focus of much of the research today, many people think this kind of technology will help us conserve energy in the future,” said Henry W. Brandhorst, director of the Center for Space Power and Advanced Electronics at Auburn University. NASA is funding the center’s power research for use on space missions.

Look for the technology eventually to filter down to consumer devices such as mobile phones and electronic organizers. “We depend on batteries, and they always seem to fail us at the worst possible time,” he said. “I just tried to turn on my Palm Pilot yesterday and nothing happened.”

Tapping into the power human bodies produce holds out the possibility of making medical devices largely self-contained. Someday, a cardiac patient may not need to get his chest cracked open every few years to replace the pacemaker battery.

But the technology’s most profound effect may be in the way people design and interact with portable devices.

Battery power dictates the size and shape of just about every electronic gizmo. Part of the reason pagers clip to a belt instead of being worn as rings or shirt buttons is the size of the batteries needed to power them.

Someday, however, with clothing that collects and stores electricity, and gadgets designed to draw power from that system, form really will follow function. Gadgets will be no bigger than they need to be to do the job. Which means soldiers will be able to carry more of the lifesaving gear they need to do their jobs.

But Paradiso of MIT said that day won’t arrive soon.

“People love this idea, but there’s a lot of work that needs to be done. Making all this work at that level is going to be pretty hard.”

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Dave Wilson is The Times’ personal technology columnist. He can be reached at dave.wilson @latimes.com.