Researchers Develop A Cell Phone That Works Without A Battery

The commercial success of battery packs shows that our gadgets are constantly power hungry, but if we are willing to scale down in capabilities, researchers from the University of Washington have demonstrated that we can get rid of batteries altogether.

The device uses a technique called backscatter. It basically uses the radio waves that already move around us to communicate. This device is still in its infant stages, but the team was able to successfully demonstrate a voice call from a battery-less phone to an Android smartphone.

Reaching this point wasn’t easy. The team had previously tested digital backscatter technology, which they call passive wi-fi, for gadgets that use a tiny amount of power. This was used to create singing posters and talking t-shirts, but it wasn’t good enough to power a cell phone. So they actually simplified the whole system.

"Converting analog human speech to digital signals consumes a lot of power," research associate Vamsi Talla, who worked on the prototype, told Wired. "If you can communicate using analog technology, you're actually more power efficient."

The team had to reinvent analog backscatter technology, which was last employed in spy kits during the Cold War. The battery-free cell phone sends digital signals when numbers are inputted in the keypad and then moves to completely analog for the voice transmission.

The signal moves over an unlicensed frequency to a base station that connects to the digital cellular network via Skype. The base station doesn’t just connect the cell phone to the network, it also delivers the necessary power to make it work. The current base station allows the phone to be at most 15 meters (49 feet) from it – not really portable, but things might change in the future by integrating base stations with phone towers.

"Real cell towers have a hundred times as much power, and would increase the range to perhaps a kilometer," added Talla.

The team is now working to improve the call quality and how the call happens. Currently, it works like a walky-talky, so you press a button to switch from speaking to listening. The team is also considering an e-ink display to send texts and possibly even a camera.

Stay tuned to see how this tech develops, and if the future will be with or without batteries, or perhaps something in between.