A new class of self-powered implantable medical devices, sensors, and portable electronics could result from nanogenerators.
|Georgia Tech Professor Zhong Lin Wang holds a sample nanowire array that can be used to power nanometer scale devices.|
To make the generators, researchers first grew arrays of zinc oxide nanowires, then used an atomic-force microscopic tip to deflect individual wires. As a wire was contacted and deflected by the tip, stretching on one side of the structure and compression on the other side created a charge separation, positive on the stretched side and negative on the compressed side. When the tip lost contact with the wire, the strain released and the researchers measured the electrical current.
The nanowire arrays were grown using standard vapor-liquid-solid processes in small tubes furnaces. Gold nanoparticles were deposited onto a sapphire substrate and place in one end of the furnace. An argon carrier gas was flowed into the furnace as zinc oxide power was heated. The nanowires grew beneath the gold nanoparticles, that serve as catalysts. The resulting arrays contained vertically aligned nanowires that ranged from 200 to 500 nm in length, 20 to 40 nm in diameter, and grew about 100 nanometers apart. A film of zinc oxide also grew between the wires on the substrate surface, creating an electrical connection between them.
This development means that these devices can not only be used in the body (since zinc oxide is non-toxic) but also wherever mechanical energy such as the hydraulic motion of seawater is available. The nanowires can be grown on crystal substrates and also on polymer-based films. Placing the nanowire arrays into felds of acoustic or ultrasonic energy. Though they are ceramic materials, the nanowires can bend as much as 50 % without breaking.For More Information Visit:
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