Fabrication of Metal/Oxide Nanostructures by Anodization Processes for Biosensor, Drug Delivery and Supercapacitor Applications

This dissertation proposed to initiate the research into the fabrication of metal/oxide nanostructures by anodization process for biosensor, drug delivery and supercapacitor applications by producing different nanostructures which lead to the potential for various applications. This study focuses on the establishment of the knowledge and techniques necessary to perform metal/oxide nanostructures on biological and energy applications. This study will investigate: (1) the sensor and drug delivery applications of micro/nano structures; (2) novel processes to innovate anodic aluminum oxide nanotube template; (3) the supercapacitor applications of anodic titanium oxide.

First, the extremely high surface area AAO coated microneedle and microneedle array can be developed as sensor and drug delivery devices. Due to the large surface area of the AAO, the film can absorb indicators to make it sensitive to testing targets. pH detection was demonstrated to show the sensing capability of the microneedle. Then, the microneedles were further built as an array by combining micromachining technique. The microneedle array provides a 3-D structure that possesses several hundred times more surface area and capacity than a traditional nanochannel template. Second, the nanoengineering process was conducted to innovate anodic aluminum oxide nanotube template. Guided anodization assisted by nanoimprint process formed AAO arrays that can be formed on controlled locations. More importantly, it shows the periodically ordered AAO array with different sizes of nanopores. With the improved AAO template, melting injection, electro/electroless deposition and sol-gel deposition were conducted to fabricate Ni nanowires/ TiO_(2) nanotubes, Ni/BaTiO_(3) core-shell nanotubes, and UHMWPE nanotubes. Third, various Ti-based alloys were anodized to form ordered nanotubes for supercapacitor application. Ti alloy oxide contains some porous layers which are not presented on TiO_(2) nanotube film. Thus, Ti alloys anodized oxide nanotubes have better supercapacitor behaviors than the conventional TiO_(2) nanotubes. However, a high surface area nanoporous Ti/TiO_(2) structure, which was fabricated by selective etching process, can accumulate large quantity of electrons and energy for supercapacitor needs. Additionally, nanoporous metals obtained by dealloying hold a unique combination of a highly conductive network and a bicontinuous open. The characteristics formed through dealloying also present a nice charge/discharge behavior and a good capacitance performance.