Battery-Free Wireless System to Power Mobile Devices

Anyone with a mobile device has likely experienced the frustration of having to be reliant on a battery. The charge never lasts long enough, and finding a source of electricity on the run is a hassle. Researchers at the University of Washington have come up with a solution to modern tech troubles with their new communication technique called “ambient backscatter.” The process uses TV and cellular transmissions to connect wireless gadgets so that they communicate with one another, reflect existing signals, and share information.

To demonstrate the ambient backscatter process, UW scientists took small, battery-free devices equipped with antennas that are about the size of a credit card. Placed within several feet from one another, they were able to send signals to a circuit board with a flashing LED light to indicate when they received information from another device. Different configurations were tested throughout Seattle, operating at ranges up to 6.5 miles away from a base TV tower.
“Our devices form a network out of thin air,” says co-author of the paper, Joshua Smith. “You can reflect these signals slightly to create a Morse code of communication between battery-free devices.”

The researchers see applications in everything from mobile devices to detecting stress and fractures in bridges and other forms of infrastructure. Their work is already garnering a great deal of attention, and earned the UW team a best-paper award from the Computing Machinery’s Special Interest Group on Data Communication 2013 conference in Hong Kong. Soon, sensors embedded in clothing and buildings could create a network that shares energy without the need to generate power in every individual device.