Engineers have created a circuit that makes cell phone batteries last up to 30 percent longer on a single charge. The trick: it converts some of the radio signals emanating from a phone into direct current (DC) power, which then charges the phone’s battery. This new technology can be built into a cell phone case, adding minimal bulk and weight.
“When we communicate with a cell tower or Wi-Fi router, so much energy goes to waste,” explained Chi-Chih Chen, research associate professor of electrical and computer engineering. “We recycle some of that wasted energy back into the battery.”
“Our technology is based on harvesting energy directly from the source, explained Robert Lee, professor of electrical and computer engineering. By Lee’s reckoning, nearly 97 percent of cell phone signals never reach a destination and are simply lost. Some of the that energy can be captured.
The idea is to siphon off just enough of the radio signal to noticeably slow battery drain, but not enough to degrade voice quality or data transmission. Cell phones broadcast in all directions at once to reach the nearest cell tower or Wi-Fi router. Chen and his colleagues came up with a system that identifies which radio signals are being wasted. It works only when a phone is transmitting.