Type of Document Master's Thesis Author Ramesh, Chetan Author's Email Address firstname.lastname@example.org URN etd-11152006-174359 Title Thermal Management of Micro Gas Chromatographs Degree Master of Science in Mechanical Engineering (M.S.M.E.) Department Mechanical Engineering Advisory Committee
Advisor Name Title Michael Murphy Committee Chair Edward Overton Committee Member Elizabeth Podlaha Murphy Committee Member Srinath Ekkad Committee Member Keywords
- Micro Heaters
- Micro Gas Chromatographs
- Temperature Programming
- Gas Chromatography
Date of Defense 2006-11-03 Availability unrestricted AbstractGas chromatography is an analytical technique for separating and analyzing individual components in a gas mixture. Applications of gas chromatographs (GCs) include chemical analysis, environmental maintenance, green house gases monitoring, and forensic analysis when used in conjunction with mass spectrometry. There has been a tremendous interest in miniaturization of gas chromatograph systems because of significantly reduced size, portability, fast response times, low power consumption and low cost.
Isothermal analysis is a chromatographic analysis at one column temperature. In temperature programming, a linear increase of column temperature with time is used during the course of the analysis. Temperature programming facilitates separation of a wider range of components, when compared to isothermal analysis, in less time. Though a few miniaturized gas chromatograph systems with temperature programming capability have been reported, all reported findings until now demonstrate very slow heating ramp rates(~5oC/sec). To enable faster analysis and to analyze a wider ranger of chemicals, higher heating rates (of the order of ~40oC/sec) have yet to be achieved.
A heater was designed to implement different temperature programming cycles for a LiGA fabricated nickel micro GC. The thermal behavior of the device was modeled using an energy-based approach to determine the thermal power requirements. Thermal stress analysis was carried out to determine the thermal stresses in the system. The heaters were fabricated by electrodepositing nickel and copper on a polyimide insulating layer on top of the nickel micro GC column. Heating ramp rates from 5oC/sec to 50oC/sec were obtained with the aid of a PID controller. The heaters were also able to maintain the column at different elevated temperatures, which showed that the heaters could be used to achieve a variety of temperature programming profiles and they offered flexibility in selecting different ramp rates and soak temperatures.
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