Zinc Oxide Coated Carbon Nanotubes for Energy Harvesting Applications

As electrical devices continue to decrease in size there is a growing desire to eliminate the need for batteries as power sources. Batteries are bulky and must be recharged or replaced periodically. In biomedical monitoring, where sensors could be implanted inside the body, the recharging and replacing of batteries presents a huge problem. It would be beneficial if small scale devices could generate their own power and therefore alleviate the need for batteries. Piezoelectric nanogenerators have proven themselves as a viable means for ambient energy harvesting. Piezoelectric materials, such as zinc oxide (ZnO), have the unique property of producing a voltage difference when subjected to mechanical strain. Proper manipulation of this voltage difference can allow for the storage of energy to power small scale devices. The objective of this research is to manufacture an energy harvesting piezoelectric generator that can transduce ambient mechanical vibrations into electrical energy that could then be stored for later use. Carbon nanotubes are used as a structural backbone for a zinc oxide piezoelectric coating and a silver electrode coating. The carbon nanotubes are chosen for their strong, flexible, and conductive properties. A Schottky diode is created at the interface of the silver electrode and the ZnO coating. This diode acts to rectify the current output of the piezoelectric coated nanotubes. Previous devices yielded a maximum current output of 1.2mA. SEM imagining was used to characterize the fabrication process. A Keithley 4200 Semiconductor Characterization System was used to characterize the power output of the devices.