Innovative Designs for High Performance Micromachined Gas Chromatographic Columns
Open Access
- Author:
- Gaddes, David Edwin
- Graduate Program:
- Bioengineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- August 30, 2013
- Committee Members:
- Srinivas A Tadigadapa, Thesis Advisor/Co-Advisor
Peter J Butler, Thesis Advisor/Co-Advisor
Siyang Zheng, Thesis Advisor/Co-Advisor - Keywords:
- Gas Chromatography Microfabrication MEMS Chemical Separation
- Abstract:
- Gas chromatography (GC) is a versatile technique used in diverse fields such as biological/medical, environmental protection, pharmaceutical, and food/agricultural. This is the premier technique to identify and quantify components of interest from a complex mixture. However, the current GC systems are bulky and expensive. Microfabricated gas chromatographic columns (µGCs) have been developed to miniaturize the state of the art systems, allowing for removal of the large and inefficient ovens as well as fabrication of a micro-total analytical system (µTAS) for on-site detection. The µGC devices also provide a platform for creation of novel geometries and stationary phases unique to microfabricated devices. Although there has been considerable success in development of µGC columns and µTAS devices, currently microfabricated devices have not matched the performance of commercial columns in a number of areas. Firstly, microfabricated columns have temperature limitations much lower than that of commercial columns. To date, microfabricated columns have not operated at temperatures above 250 °C due to the epoxies used in the world-to-device connections, while standard commercial columns operate at temperatures up to 350 °C. The thermal limitations of the µGC devices prevent the use of these devices with a large number of compounds typically separated using gas chromatography. Additionally, the separation efficiency of the microfabricated columns have not matched that of commercial columns and no direct comparison of µGC columns to commercial columns has been made. Finally, there is a need for a seamless world-to-device connection to eliminate detrimental dead space and improve column efficiency. Here we address the problems listed above. We have developed novel microfabricated channel designs capable of improved chromatographic performance and allowing for high throughput and lengths up to 10 meters. To operate at high temperatures (up to 400 °C) we have fabricated interfacing and packaging techniques enabling microfabricated columns and have demonstrated the first high temperature separation with a µGC column. We have optimized the world-to-device microfluidic interconnection removing dead volume at the inlet. We have benchmarked the performance of the microfabricated column against commercially available conventional columns and displayed a clear solution to improve the separation efficiency of microfabricated columns. We expect the results of this work to further the µGC field in both research and commercial aspects.