By Ben Coxworth — Gizmag
Four years ago, we first heard about how Korean scientists had proposed using sound to charge mobile phones. They explained that it could be done via a piezoelectric effect, in which zinc oxide nanowires converted sound-caused vibrations into electricity. At the time, the researchers couldn’t generate enough of a current to actually charge a phone. Now, however, scientists from Nokia and Queen Mary University of London (QMUL) have succeeded in doing so.
Like the Korean team, the Nokia/QMUL researchers utilized zinc oxide, in the form of a sheet of tiny nanorods. As is the case with other piezoelectric materials, zinc oxide produces an electrical current when subjected to mechanical stress. The nanorods will actually bend in response to sound waves, creating that stress in the process.