Graduation Year

2010

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Mechanical Engineering

Major Professor

Ashok Kumar, Ph.D.

Keywords

Biosensor, DNA, Nanocrystalline diamond, Carbon nanotube, Thermoelectric

Abstract

In the past decade, the use of nanotechnology as a tool to develop and fabricate new structures and devices for biological sensing and energy applications has become increasingly widespread. In this work, a systematic study has been performed on one-dimensional nanomaterials, with a focus on the development of miniaturized devices with a "bottom up" approach. First, members of the nano - carbon family are utilized for biosensing applications; in particular, carbon nanotubes as well as nitrogen - doped and boron - doped nanocrystalline diamond (NCD) films. These carbon - based materials possess several unique electrochemical properties over other conductive materials which make them suitable for biosensing applications. Single walled carbon nanotubes were deposited on a glass carbon electrode and modified for the detection of Salmonella DNA hybridization.

Electrochemical impedance spectroscopy (EIS) was used as the method of detection and a detection limit of 10?? M was achieved. Nanocrystalline diamond was grown using a microwave enhanced plasma chemical vapor deposition method. The diamond electrodes were doped with either boron or nitrogen to provide substrates and characterization was performed using scanning electron microscopy, atomic force microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, UV-vis spectroscopy, as well as by electrochemical methods. Modified boron - doped NCD was able to detect Salmonella DNA hybridization via EIS and fluorescent microscopy. The detection limit for these genosensors was found to be 0.4 micrometer complementary DNA. Boron - doped and nitrogen - incorporated nanocrystalline diamond also served as functionalized electrodes for lactic acid detection. It was found that the boron - doped electrodes could detect 0.5 mM lactic acid in a phosphate buffer solution.

Second, bismuth antimony nanowires were grown in an anodized alumina template for the fabrication of a thermoelectric cooling device. Bismuth antimony nanowires were chosen due to their high thermoelectric efficiency compared to their bulk material counterpart. The development of a successful anodized template was achieved and EIS was used to diagnose the optimal etch parameters of the barrier oxide layer for nanowire growth. Bismuth antimony nanowires were grown directly on a silicon substrate and a thermoelectric cooling device was fabricated. The nanowires exhibited a thermoelectric efficiency of 0.18 at room temperature.

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