Imagine walking down Fifth Avenue in the heart of Manhattan while the sounds of the city surround you: the cabbie is honking his horn, the store owner is blasting music, and construction workers are carrying on a loud conversation. Now imagine that all of this noise gives your smartphone a battery boost! This scenario could be a reality soon thanks to scientists from Nokia and Queen Mary University of London (QMUL), who have successfully charged a phone using zinc oxide nanowires that convert sound-caused vibrations into electricity — called the piezoelectric effect.
It sounds completely unreasonable, but new technology could harvest the energy of sound to charge future cell phones. The QMUL researchers sprayed a coating of liquid zinc oxide onto a plastic sheet and used a mixture of chemicals and heat to grow an array of nanochemicals. The resulting nanorod sheet was then placed between two electrical contact sheets, made with ordinary aluminum foil instead of more expensive gold, where they responded to vibration and movement from everyday sounds.
The energy-harvesting prototype is about the size of a Nokia Lumina 925 and is capable of generating up to five volts from everyday background noise. That is more than enough juice to charge a typical smartphone.
“Being able to keep mobile devices working for longer, or do away with batteries completely by tapping into the stray energy that is all around us is an exciting concept,” said Dr Joe Briscoe from QMUL’s School of Engineering and Materials Science. “We hope that we have brought this technology closer to viability.”