Doctoral Dissertations

Date of Award

5-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Michael Sepaniak

Committee Members

Georges Guiochon, Mark Dadmun, Jayne Wu

Abstract

The fundamental motivations for scaling existing technological platforms down to lab on chip dimensions are applicable in nearly all scientific disciplines. These motivations include decreasing waste, improving throughput, and decreasing time consumption. Analytical tools, such as chromatographic separation devices, can additionally benefit from system miniaturization by utilizing wafer-level fabrication technology, allowing for the rational design and precise control of variables which ultimately affect separation performance. With the use of microfabrication techniques, we have developed an original processing sequence for the fabrication of silicon oxide enclosed pillar arrays integrated within a fluidic channel. These pillar arrays create a highly uniform submicron scale architecture of solid supports for subsequent stationary phase – mobile phase interactions, while demonstrating substantial improvements in separation efficiency and permeability over traditional packed bed and monolithic columns. The general performance of these microfluidic devices is studied by optimizing the chip architecture and instrumental design to improve the stability of the pillar arrays, improve the sample injection, enhance the pillar surface characteristics, and improve the separation performance. We additionally explore simple and straightforward stationary phase modification techniques for partition based chromatography. Finally, we address the detection challenges of our design by creating the first fully integrated microfluidic chip based platform to combine separation capabilities with real time surface enhanced Raman detection.

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