Mobile phones `could soon be charged by the power of speech`

The technology would also be able to harness background noise and even music to charge a phone.

London: Imagine charging your mobile phone by simply speaking into the handset. Well your imagination may soon turn into a reality, thanks to a research that promises a way to recharge cell batteries using the power of speech.
Electrical engineers in South Korea have developed a new technique for turning sound into electricity, allowing a mobile to be powered up while its user holds a conversation, `The Sunday Telegraph` reported.

The technology would also be able to harness background noise and even music to charge a phone while it is not in use, say the engineers.

Dr Sang-Woo Kim, who has been developing the design at the Institute of Nanotechnology at Sungkyunkwan University in Seoul 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.

"The latter development would have the additional benefit of reducing noise levels near highways by absorbing the sound energy of vehicles."

The technology uses tiny strands of zinc oxide sandwiched between two electrodes. A sound absorbing pad on top vibrates when sound waves hit it, causing the tiny zinc oxide wires to compress and release. This movement generates electrical current that can then be used to charge a battery.

A prototype of the technology was able to convert sound of around 100 decibels - the equivalent of noisy traffic- to generate 50 millivolts of electricity, say the engineers.

This is not enough to charge a phone properly, but Dr Kim and his colleagues hope that by altering the material the wires are made from they will be able to produce more energy at lower sounds levels.

Dr Kim said: "Our current output performance can be applied to various electronic devices with low-power consumption such as self-powered sensors and body-implantable tiny devices. We believe that we can realise more efficient sound-driven nanogenerators."


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