Battery-free cellphone can make calls, no charging is ever needed (Video)

Have you ever thought about the possibility to have a phone that does not need to be recharged? Such device already exists. And, in fact, it is a 100% battery-free cellphone.

A battery-free cellphone prototype. Image credit: Vamsi Talla, Bryce Kellogg, Shyam Gollakota, Joshua R. Smith / University of Washington

Researchers at University of Washington have demonstrated the first battery-free cellphone design. This model still uses power, but only a few micro-watts of electricity are enough to feed the circuitry responsible for the basic call functions.

The design can electronically sense speech using ultra-low power components, activate the earphones, and seamlessly switch between uplink and downlink communications in real-time.

How the battery-free phone generates power and are there any limitations?

The system is designed to optimize the transmission and reception of speech in terms of consumer power. The phone itself also acts as a so-called energy harvester, using its internal antenna and picking the energy from electromagnetic signals radiated by the base station.

The power gained this way is sufficient to ensure the continuous operation of the battery-free cellphone.

The device’s prototype is made from regular off-the-shelf electronic components all of which are mounted on a standard printed circuit board.

The only serious limitation is that the phone works up to 9.4 meters (31 feet) away from the base station. Or alternatively, the phone can use a bit of solar energy – some of it is collected using small photodiodes. Then, the communication range is extended up to 15.2 m (50 ft) away from the base station.

Of course, internal sound amplification capabilities are also limited – this is why you need to direct your voice straight to its microphone, in order to achieve good voice quality on the receiving end.

Future plans

The team of developers also demonstrated a custom bridged base station using which the battery-free cellphone could make its first Skype call via a cellular network.

Engineers say this is just the first prototype – they expect to extend its operational range in the future, which would be a significant step towards fully functional battery-free communication devices.

Written by Alius Noreika