Self Charging Electronics

Researchers at Texas A&M University have made significant inroads in the area of power harvesting; a field focused on building self powered devices that don’t need replaceable power supplies such as batteries. Their findings show that approximately 21 nanometer thick piezoelectric materials convert energy at nearly double the rate of similar materials at other thicknesses. Eventually, cell phones and other small electronics using these materials may generate enough energy to power themselves.
Piezoelectric materials convert mechanical energy to electromagnetic energy. In the case of a cell phone, the sound waves produced by a user’s voice could be converted to electric energy used to power the phone. Similarly, the sound of songs or audiobooks playing on an MP3 player could power the player. Potential applications are widespread, ranging from other consumer products to devices used by law enforcement and the military.
Professor Tahir Cagin of the Laboratory of Computational Engineering of Nanomaterials within the Department of Chemical Engineering at Texas A&M and several colleagues from the University of Houston have been experimenting with piezoelectric materials of different thicknesses and discovered a sweet spot at 21 nanometers. The energy production significantly drops off when thinner (less than 20 nm) or thicker (more than 23 nm) piezoelectric materials are used.
Dr. Cagin began to look at the properties of thinner piezoelectric materials because the smaller materials are more likely to interact heavily with their environment. Think of it this way: the amount of wind needed to move a human hair (which is significantly thicker than these nanomaterials) is substantially less than the amount of wind needed to forcibly move an entire human being.
While regular piezoelectric materials are currently used to harvest power in limited ways (such as nightclubs using piezoelectronic dance floors to power the lights), research into nanoscale piezoelectric materials is still in its infancy. Practical, self-sustaining electronics are still a long way from reality. However, Cagin’s research is a major step forward in this area and hopefully will result in practical power harvesting in the future.
TFOT has reported on other applications of nanotechnology in small consumer electronics, including the Nokia Morph technology designed to create flexible, shape changing mobile devices and self assembling nanowires that can be used for any number of medical or technological applications. TFOT has also explored other alternative power sources including an electrically-generated fuel cell based on Gore-Tex and a new film that increases the energy production of direct methanol fuel cells by up to 50 percent.
More information on Dr. Cagin’s research can be found in the Texas A&M press release found here. You can also access Dr. Cagin’s faculty page with links to further research here. The abstract of the paper on nanoscale piezoelectric materials published in the September 25, 2008 issue of Physical Review B can be found here.

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