Scientists have discovered a way of charging a mobile phone by converting microwaves into an electrical current.
According to the team from Duke University, North Carolina, in future satellite, sound or Wi-Fi signals could be “harvested” to charge phones in areas without access to power.
The team used metamaterials, which capture wave energy and convert them for other uses in making their device, which is as efficient as using solar panels, the researchers said.
“Until now, a lot of work with metamaterials has been theoretical”, engineering student Alexander Katko said.
“We are showing that with a little work, these materials can be useful for consumer applications.”
Fellow team member Allen Hawkes went on: “We were aiming for the highest energy efficiency we could achieve.
“We had been getting energy efficiency around six to 10 per cent, but with this design we were able to dramatically improve energy conversion to 37 per cent, which is comparable to what is achieved in solar cells.”
The team used fibreglass and copper conductors on a circuit board to convert microwaves into 7.3 volts of electricity.
USB chargers used on mobile phone batteries and cameras provide about five volts.
The researchers hope in future the technology can be built in to mobile phones so that they could be recharged wirelessly when they are not being used.
The full report is set to be published in the journal Applied Physics Letters next month.