Someday, you might be able to charge your iPod or cell phone just by taking a walk or even plugging in to your own bloodstream. Georgia Tech University researchers announced Thursday they have created a prototype “nanogenerator” that can produce electricity to power portable devices using mechanical vibrations, sonic waves, or the flow of blood or other liquids. The device, developed in part through a grant from the military’s research agency, is at least a few years away from hitting store shelves alongside all those iPod and cell phone accessories. But researchers say it definitely shows that tiny power generators could someday make batteries obsolete. “If you had a device like this in your shoes when you walked, you would be able to generate your own small current to power small electronics,” said Zhong Lin Wang, a professor in Georgia Tech’s School of Materials Science and Engineering. Wang predicted that a device based on his prototype could be on the market in five years or less. “This could have very broad impacts,” he said. For the military, such a device could power explosives or wearable biochemical sensors, Wang said. In medicine, it could be implanted into the body and used to power electronic devices that measure blood pressure. And for on-the-go consumers, it could someday power a wide array of portable devices. Wang’s nanogenerator works something like a miniature windmill or hydroelectric dam. Inside the device, tiny microscopic wires wave back and forth whenever they’re subjected to movement. When the wires move, they brush against a silicon electrode, producing tiny sparks of electricity. Wang said he thinks devices could be built containing millions or even billions of the zinc oxide nanowires. He and other researchers have plenty of work to do before any such product hits the market. In coming months, Wang said, they’ll be working on ways to increase the voltage output from the devices. In part, they hope to accomplish that by figuring out ways to produce zinc oxide wires that are more uniform in length. That said, he and others have “pushed it from scientific concept to true prototype devices,” Wang said. In addition to the military’s Defense Advanced Research Projects Agency, funding for the project comes from the National Science Foundation and the Emory-Georgia Tech Center of Cancer Nanotechnology Excellence. Details of the research are to be published in today’s edition of the academic journal Science.