Nanowires Twist and Turn to Generate Electricity
Piezoelectric technologies are all the rage these days: just over the past year, we've reported on people-powered staircases, acoustic heat-engine devices and electricity-generating ticket gates. Now combine that with nanotechnology, another hot field du jour, and you've got yourself the brainchild of Min-Feng Yu: a nanowire capable of generating a voltage upon mechanical deformation.
Yu, a professor of mechanical science and engineering at the University of Illinois, and his graduate students used a single crystal of barium titanate, an oxide of barium and titanium commonly found in transducers and microphones, measuring 280 nanometers in diameter and 15 microns in length. The researchers fastened the wire to two platforms - one of which was movable - and induced mechanical vibrations that resulted in the production of a very slight voltage (less than one quintillionth of a joule). Though they didn't experiment with them, Yu and his students believe that other vibrations, such as sound waves, could produce the same result.
"With the development of this precision testing apparatus, we successfully demonstrated the first controlled measurement of voltage generation from an individual nanowire. The new testing apparatus makes possible other difficult, but important, measurements, as well. In addition, because of the fine precision offered by the mechanical testing stage, it should also be possible to quantitatively compare the intrinsic properties of the nanowire to those of the bulk material. This will allow us to study the scale effect related to electromechanical coupling in nanoscale systems," said Yu.
Given the minuscule amount of electricity they generate, these nanowires aren't likely to be incorporated into everyday gadgets or appliances any time soon. However, with the rapid progress being made in nanotechnology and related fields, they could soon help power the next generation of mini-devices.