(USA)

Researchers at an American university have been making Skype calls using a battery-free mobile phone.

The University of Washington (UW) team has developed a phone that can be powered by ‘ambient radio signals or light’ to get the few ‘microwatts of power’ it needs.

“We’ve built what we believe is the first functioning cellphone that consumes almost zero power. To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed,” said associate professor Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at the UW. ”

The phone taps into the minuscule vibrations in the speaker generated when a person talks or is listening. The UW team said an ‘antenna connected to those components converts that motion into changes in standard analog radio signal emitted by a cellular base station. This process essentially encodes speech patterns in reflected radio signals in a way that uses almost no power.’

A base station developed by the team is able to send and receive radio signals. This technology could ultimately be added to Wi-Fi routers.

“You could imagine in the future that all cell towers or Wi-Fi routers could come with our base station technology embedded in it,”explained co-author Vamsi Talla, a former UW electrical engineering doctoral student and Allen School research associate. “And if every house has a Wi-Fi router in it, you could get battery-free cellphone coverage everywhere.”