New research in piezoelectronics brings us closer to self-charging tech
Future cell phone users may never need to plug in, new research suggests. Thanks to advances in harnessing piezoelectronics, phones and other gadgets can charge their batteries from the sounds and vibrations around them.
Piezoelectrics are materials that generate an electric charge when twisted, bent, or otherwise stressed, and much previous research has involved collecting exerted mechanical energy through shoes and floors with piezoelectric generators.
In 2010, Korean researches first proposed the idea of harnessing the energy from sound waves to power cell phones and other mobile gadgets using the reciprocal nature of piezoelectrics; “[j]ust as speakers transform electric signals into sound, the opposite process – of turning sound into a source of electrical power – is possible,” said Young Jun Park and Sang-Woo Kim, co-authors of the study.
At that time, the researchers were only able to generate about 50 millivolts — significantly less than the 4 or 5 volts required to charge a cell phone. Recently, however, a partnership between Nokia and Queen Mary University of London (QMUL) has succeeded generating the needed voltage with the technology.
As Phys.org reported, the team created an energy-harvesting nanogenerator that can use background noise — such as voices, music, and traffic sounds — to charge a mobile phone. As QMUL’s Dr. Joe Briscoe explains,
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. We hope that we have brought this technology closer to viability.
Like the Korean team, the Nokia and QMUL researchers used a spraying technique to form zinc oxide into a sheet of nanorods. The minute nanorods bend in response to sound waves, creating stress and generating electricity. While gold has traditionally been used as a highly conductive material in electrical mechanisms, the team found that zinc oxide — also highly conductive — can serve as a cheaper alternative for mass use.
Another more cost-effective alternative for power generation comes from researchers at the Lawrence Berkeley Natural Laboratory, who developed a piezoelectric bacteria-eating virus. With a single finger tap, thin layers of the virus were found to generate 6 nanoamps of current and 400 millivolts of potential, which is enough to power a small liquid-crystal display or about one fourth of a AAA battery’s power.
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