New research in nanotechnology could mean you'll be able to charge your phone with your voice.
Utilising the sounds made when you’re talking on the phone, and background noise, this would be changed into a residual electrical charge. This could also be done while the phone isn’t in use.
At the Institute of Nanotechnology at Sungkyunkwan University in Seoul, South Korea, Dr Sang-Woo Kim, said: "A number of approaches for scavenging energy from environments have been intensively explored.
"The sound that always exists in our everyday life and environments has been overlooked as a source. This motivated us to realise power generation by turning sound energy from speech, music or noise into electrical power.
"Sound power can be used for various novel applications including cellular phones that can be charged during conversations and sound-insulating walls near highways that generate electricity from the sound of passing vehicles."
He added: "The latter development would have the additional benefit of reducing noise levels near highways by absorbing the sound energy of vehicles."