To help maintain the nanowires connection to the Kevlar, the researchers apply two layers of tetraethoxysilane (TEOS) to the fiber. First we coat the fiber with the polymer, then with a zinc oxide layer, Wang explained. Then we grow the nanowires and re-infiltrate the fiber with the polymer. This helps to avoid scrubbing off the nanowires when the fibers rub together.
Finally, the researchers apply a 300 nanometer layer of gold to some of the nanowire-covered Kevlar. The two different fibers are then paired up and entangled to ensure that a gold-coated fiber contacts a fiber covered only with zinc oxide nanowires. The gold fibers serve as a Shottky barrier with the zinc oxide, substituting for the platinum-tipped electrode used in the original nanogenerator.
To ensure that the current they measured was produced by the piezoelectric-semiconductor effect and not just static electricity, the researchers conducted several tests. They tried rubbing gold fibers together, and zinc oxide fibers together, neither of which produced current. They also reversed the polarity of the connections, which changed the output current and voltage.
By allowing nanowire growth to take place at temperatures as low as 80 degrees Celsius, the new fabrication technique would allow the nanostructures to be grown on virtually any shape or substrate.
As a next step, the researchers want to combine multiple fiber pairs to increase the current and voltage levels. They also plan to improve conductance of their fibers.
However, one significant challenge lies head for the power shirt washing it. Zinc oxide is sensitive to moisture, so in real shirts
|Contact: John Toon|
Georgia Institute of Technology Research News