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Harvesting energy from sound

article image The final device generates 5V, enough to charge a phone.

SCIENTISTS from the Queen Mary University of London and Nokia have collaborated to create an energy harvester that can charge a phone using noise.

In 2013 Dr Joe Briscoe and Dr Steve Dunn from QMUL’s School of Engineering and Materials Science found they could improve the performance of solar cells by playing pop and rock music to them.

Developing this research further, the joint team of Nokia and QMUL researchers worked to create an a nanogenerator that could be used to charge a mobile phone using everyday background noise – such as traffic, music, and our own voices.

At the core of the energy harvester is zinc oxide, which creates a voltage when it is deformed. The zinc oxide was formed into nanorods and coated onto the surface of the nanogenerator.

When this surface is squashed or stretched, the nanorods then generate a high voltage.

Vibrations and movements of the nanorods caused by sound also cause them to generate voltage. This electricity is harvested by electrical contacts on both sides of the rods.

The researchers found ways to cut costs in the production of the nanogenerators, by developing a process to spray a layer of zinc oxide onto the plastic sheet. When this coated sheet is put into a mixture of chemicals and heated, nanorods grew on the surface of the sheet.

The team also replaced gold with aluminium foil as an electrical contact.

The final device generates 5V, enough to charge a phone.

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