Battery free phone

Battery-free smartphones could be available by 2018

Image credit: University of Washington

Researchers from the University of Washington – who have revealed a prototype of a phone which runs entirely without batteries – hope to have a battery-free phone ready for the market in months.

The phone works by harvesting small amounts of power from radio signals, radio frequency (RF) waves and carrying out high-power processes at a base station.

The basic proof-of-concept prototype consists of an uncovered circuit board with no screen. Headphones are attached to receive a call and a button must be pressed to switch between speaking and listening: the two cannot be done at the same time. The phone runs on just 2-3mW of power.

Circuit board labelled diagram of phone

University of Washington

Image credit: University of Washington

As the user speaks, the analogue vibrations of their voice are transmitted as changes in voltage into radio waves, produced by and reflected back to a base station with the spoken words “encoded” inside. At the base station, they are converted into digital data and sent via Skype to the other caller.

“Ambient RF waves are all around us so, as an example, your FM station broadcasts radio waves, your AM stations do that, your TV stations, your cellphone towers. They are all transmitting RF waves,” said Dr Vamsi Talla, a researcher in the Sensor Systems Laboratory at the University of Washington, and CTO of Jeeva Wireless, a company in the process of commercialising this ultra-low power technology.

While the prototype is a long way from the smartphones we typically use today, the researchers intend to rapidly improve their technology, next adding a low-power screen to allow for texting and a basic camera. They hope to accelerate the development of the battery-free phone quickly enough to release a product in eight to nine months’ time.

The team may also create a version of the phone which uses a small solar cell to provide power.

“In the future every smartphone will come with a battery-free mode where you can at least make a voice call when your battery is dead,” a member of the team said. The researchers suggest that this could enable urgent calls – such as to emergency services – to be made even after a phone has run out of battery power.

With the limited battery life proving to be one of the most frustrating problems with smartphone and tablet technology, researchers around the world are experimenting with different solutions, such as longer-lasting batteries and multi-use portable chargers. Researchers at the University of Bristol and the University of Surrey are, for instance, developing supercapacitors which could allow phones to be charged in a matter of minutes.

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