News
News Categories

This battery-free mobile phone makes calls by harvesting ambient power

By James Lu - on 22 Jul 2017, 10:44am

This battery-free mobile phone makes calls by harvesting ambient power

Researchers from the University of Washington have developed a battery-free mobile phone that can make phone calls powered only by radio waves and light.

The low-power prototype can only make and receive calls, and lacks a touchscreen or data connection, but it could be vital in an emergency.

The phone consumes between two and three microwatts of energy and harvests its energy from radio signals sent out by a special base station and a tiny on board solar cell. The research team state that their base stations could be installed in cell towers and Wi-Fi routers, to provide power to any nearby devices.

The phone can also transmit signals to the station through a combination of reflecting those radio wave signals back and the electromagnetic pulses generated by the vibrations of the phone's diaphragm when speaking into its microphone. It sends a series of digital pulses to a receiver, which encodes it into a Skype call that can be placed to any number.

To make the device work, the team first had to eliminate the most power hungry part of a normal mobile phone: The conversion of analog audio signals into digital data. According to the post on the University website, “this process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources.”

To get rid of that part of the process, the researchers devised a way to use the tiny vibrations of the phone’s microphone and speaker to encode incoming and outgoing signals. Unfortunately, this doesn’t allow the phone to simultaneously send and receive audio. Instead, the caller has to hold in a send or receive button while sending or receiving similar to how a walkie-talkie functions.

"This we believe is a major leap in the capability of battery-free devices and a step towards a fully functional battery-free cellphone," the researchers said.

Source: University of Washington

Join HWZ's Telegram channel here and catch all the latest tech news!
Our articles may contain affiliate links. If you buy through these links, we may earn a small commission.