Design and Performance Evaluation of a Gas Chromatograph Micromachined in aSingle Crystal Silicon Substrate

摘要

This investigation designed and developed a miniature gas chromatograph (GC)using silicon micromachining techniques. The GC is composed of a miniature sample injector (10 micro-l sample loop); a 0.9 m long, rectangular-shaped (300 micrometers width and 10 micrometers height) capillary column coated with a 0.2 micrometer thick copper phthalocyanine (CuPc) stationary phase; and a dual-detector scheme incorporating a CuPc-coated chemiresistor and a 125 micrometer diameter thermal conductivity detector bead. Micromachining was employed to fabricate the sample injector interface, the GC column, and the dual-detector cavity. A novel processing technique was developed to sublime the CuPc stationary phase coating on the GC column walls. The miniature GC system has been used to separate parts-per-million ammonia and nitrogen dioxide concentrations in less than 30 minutes (10 microliters sample injected at 40 psi). A secondary discovery was the heat of adsorption of nitrogen dioxide (0.38 eV) on a polycrystalline CuPc film (0.2 micrometer thick). This research demonstrated the utilization of a miniature GC to investigate the adsorptive properties of thin films. Also, the time-domain performance model of the miniature GC developed in this investigation will facilitate the optimization of future miniature GC designs....Gas chromatograph, Micromachining, Chemiresistor, CUPC, Copper phthalocyanine, GC, Anodic bonding, Silicon, Heat of adsorption, Thin film, Ammonia, Nitrogen dioxide.