Title page for ETD etd-06052009-023407


Type of Document Master's Thesis
Author Zareian-Jahromi, Mohammad Amin
Author's Email Address zareian@vt.edu
URN etd-06052009-023407
Title MEMS-Based Micro Gas Chromatography: Design, Fabrication and Characterization
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Agah, Masoud Committee Chair
Lu, Guo-Quan Committee Member
Meehan, Kathleen Committee Member
Raman, Sanjay Committee Member
Keywords
  • MEMS
  • Nanotechnology
  • coating techniques
  • mono layer protected gold
  • gad chromatography
Date of Defense 2009-05-22
Availability unrestricted
Abstract
This work is focused on the design, fabrication and characterization of high performance MEMS-based micro gas chromatography columns having wide range of applications in the pharmaceutical industry, environmental monitoring, petroleum distillation, clinical chemistry, and food processing. The first part of this work describes different approaches to achieve high-performance microfabricated silicon-glass separation columns for micro gas chromatographic (µGC) systems. The capillary width effect on the separation performance has been studied by characterization of 250 µm-, 125 µm-, 50 µm-, and 25 µm-wide single-capillary columns (SCCs) fabricated on a 10×8 mm2 die. The plate number of 12500/m has been achieved by 25 µm-wide columns coated by a thin layer of polydimethylsiloxane stationary phase using static coating technique. To address the low sample capacity of these narrow columns, this work presents the first generation of MEMS-based “multicapillary” columns (MCCs) consisting of a bundle of narrow-width rectangular capillaries working in parallel. The second contribution of this work is the first MEMS-based stationary phase coating technique called monolayer protected gold (MPG) for ultra-narrow single capillary (SCC) and multicapillary (MCC) microfabricated gas chromatography (μGC) columns yielding the highest separation performance reported to date. This new μGC stationary phase has been achieved by electrodepositing a uniform functionalized gold layer with an adjustable thickness (250nm-2µm) in 25μm-wide single columns as well as in four-capillary MCCs. The separation performance, stability, reproducibility and bleeding of the stationary phase have been evaluated over time by separating n-alkanes as non-polar and alcohols as polar gas mixtures.
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