REPORTED IN PHYS.org – New tech keeps your smart phone charged for 30 percent longer
May 26, 2015 by Pam Frost Gorder
New technology developed at The Ohio State University makes cell phone batteries last up to 30 percent longer on a single charge.
The patented circuitry 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, without adding more than a trivial amount of bulk and weight.
Some of the inventors, all engineering researchers at Ohio State, are working with a spin-off company to further develop the technology and will launch a Kickstarter campaign in June for market validation and fund development.
“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.”
There are some products newly on the market that harvest stray radio signals to charge tiny wireless devices such as temperature sensors. But the Ohio State invention is many times more powerful and efficient, said Robert Lee, professor of electrical and computer engineering.
“These other devices are trying to harvest little bits of energy from the air,” Lee said. “Our technology is based on harvesting energy directly from the source. They can capture microwatts or even nanowatts (millionths or billionths of a watt), but cell phones need milliwatts (thousandths of a watt) or higher.”
By Lee’s reckoning, nearly 97 percent of cell phone signals never reach a destination and are simply lost. Not all of it can be recaptured, but some can.
“No one can charge a cell phone from the air, but we can reduce power consumption by retrieving some of those lost milliwatts. Think of it as a battery extender rather than a charger,” Lee said.
The work is a natural outgrowth of Chen’s research, which focuses on the design of small antennas and radio frequency energy-harvesting circuitry. Whether he’s developing antennas to be embedded in clothing or a device for detecting and neutralizing buried land mines, the key is designing a circuit that quickly and easily identifies signals of interest, even when the antenna is moving.