Advancement of Micro Gas Chromatographs and Their Core Components

The development of portable vapor sensors is of high interest for in situ and real-time chemical analysis. These sensors are targeted at industrial and environmental monitoring as well as point-of-care applications. Advances in microelectromechanical systems (MEMS) technologies has allowed for the miniaturization of benchtop gas chromatography (GC) into portable micro GC (µGC) systems that allow for field analysis. This dissertation details the development of critical µGC components, especially microcolumns and micro photoionization detectors (PIDs), along with their assembly into prototype µGC systems for in situ testing. Two different microcolumn coatings were developed to broaden the range of chemical separations suitable for µGC analysis, including a micro porous layer open tubular column for light compound analysis and micro ionic liquid column for simultaneous analysis of polar and nonpolar compounds. A new column coating method was also demonstrated to improve separation performance without the need for increasing column length or any auxiliary components. A micro helium desorption PID (µHDPID) fabrication process was developed to allow for the robust fabrication of universal vapor detectors, complementing the increased range of separations from the new microcolumn coatings. A high sensitivity PID system was also developed with sub-pg detection limits, comparable to or even surpassing that of benchtop flame ionization detectors. These components were assembled into two prototype systems, one for hydrogen and methane detection for breath analysis, and another ultracompact µGC system with the entire system capable of being contained within a 1.1 L box, including batteries, pumps, and electronic readout boards. Together, these developments are aimed at increasing the range of applications that can be targeted by µGC by broadening its separation and detection capabilities, as well as improving the sensing performance.PhDElectrical and Computer EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/171314/1/maxli_1.pd