Scientists have already devised systems that allow electronic devices to scavenge power from ambient electromagnetic energy sources such as radio waves. While the technology has generally been limited to small devices such as wireless sensors, a research team has recently created a scavenging system that charges a smartphone's battery, letting it last up to 30 percent longer per charge – and the system does so using radio signals emanating from the phone itself.
Developed by scientists at The Ohio State University led by Prof. Chi-Chih Chen, one of the keys to the system is the fact that it's harvesting radio waves where they're still strong, right at their point of origin. By contrast, systems that attempt to generate electricity using whatever "diluted" waves happen to be passing through the air tend to take a long time to produce even a modest charge.
The system, which could be built into a smartphone case, works by analyzing what parts of a phone's outgoing signal aren't reaching a cell tower or Wi-Fi router – given that phones typically transmit in all directions at once in order to reach the closest tower, wherever it is, a large percentage of their signal is often wasted.
That "unused" radio signal, which is essentially a high-frequency form of alternating current, is then converted to DC and used to charge the battery. As a result, not only does the battery last longer, but there's no loss in data transmission or sound quality.
The technology is being developed through spin-off company Nikola Labs, and a crowdfunding effort is being planned to help finance production. It is estimated that the initial product, which may end up taking the form of a stick-on phone skin, will cost around US$100. The researchers would also like to find an industrial partner that could manufacture the technology directly into new phones.
Source: The Ohio State University