Monolithic integration and advancement of micro-gas chromatography – from components to systems and from 1D to 2D

Microfabricated gas chromatography (μGC) offers a powerful portable vapor analysis method for applications such as environmental protection and monitoring, workplace hazard analysis, and biomedicine. μGC systems with microfluidic photoionization detectors (μPID) have demonstrated ppt (parts-per-trillion) level detection of volatile organic compounds. In this thesis, I first introduced a monolithic integration process that enables the fabrication of the micro-column (μcolumn) and μPID on a single chip, resulting in an ultracompact μGC system weighing 0.9 kg and occupying 0.9 liters. I then addressed μPID degradation mechanisms and extended its lifetime through ultrathin silica integration. To enhance μPID’s sensitivity, I developed an avalanche photoionization detector (APID) that amplifies ionized gas electrons through the avalanche process of an embedded reversely biased P/N junction. Finally, a monolithically integrated flow-restricted pneumatic modulator on the μcolumn is introduced and used to construct a first-of-its-kind automated portable comprehensive 2D μGC without any benchtop components.

Chair: Professor Xudong (Sherman) Fan