Scientists use surplus radio signals for smartphone charging

Ohio State University scientists have found a way to use the useless radio signals emitted by a smartphone to recharge the battery. The battery could last up to thirty percent longer if a connection is active.

The system was developed by researchers Chi Chih Chen and Robert Lee of Ohio State University. They use a technique that is not new in itself: recovering energy from radio signals is used to power small sensors. Smartphones consume much more power, but can still benefit from it: they can run longer on a battery charge.

The invention recaptures part of the radio signals emitted by a telephone and converts them into electricity, which is used to recharge the battery. This involves alternating voltage with a very high frequency, while electronics operate on direct current. The system therefore has a small rectifier to convert the alternating voltage into direct current.

If the system receives too much of the transmitted signals, the quality of the connection suffers. Smartphones send out radio signals in all directions to reach the nearest Wi-Fi router or telephone tower, scattering some of the signal uselessly. According to Lee, 97 percent of the signal is lost. The scientists therefore developed a system that would automatically receive the maximum amount of radio signals without causing problems for the connection.

According to the researchers, their invention ensures that the battery lasts up to thirty percent longer after a full charge. The system will not work when receiving signals only, or when the phone is used without a connection.

The researchers founded the company Nikola Labs to bring the technology to market. They previously announced that they would launch a Kickstarter campaign in June to fund further development. Initially, the invention will be built into a $99 iPhone case, which should be delivered in September. Ultimately, they hope to find a manufacturer who wants to integrate the technology into a smartphone. The researchers also see applications for other mobile devices, such as wearables, sensors and medical devices.

The iPhone case that Nikola Labs plans to offer on Kickstarter soon.