updated 12:00 pm EDT, Mon May 9, 2011
Korean engineer shows noise-powered generator
Electrical engineers in Korea have created a method of recharging a cellphone by sound. This could include ambient noise, music or even speech so a user having a conversation would charge the battery, UK daily The Telegraph reported this weekend. The louder the noise, the more electricity flows into the battery as well.
The design work is headed up by Dr. Sang-Woo Kim at the institute of nanotechnology at Sungkyunkwan University in Seoul, South Korea. Kim's other potential application for the technology includes sound-insulating walls near highways that generate electricity from the sound of passing vehicles.
"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," Kim said.
The tech relies on small strands of zinc oxide placed between two electrodes. This is topped off by a sound-absorbing pad that vibrates when sound waves hit it. The waves cause the zinc oxide wires to compress and release, causing electrical current. A prototype converted nearly 100 decibels to generate 50 millivolts of electricity. That noise level is represented by hearing a car horn from 15 feet away.
Different material for the wires in the nanogenerator would produce more energy at lower sound levels. When the technology will show up in consumer devices hasn't been revealed.