Silicon-micromachined gas chromatography system used to separate and detect ammonia and nitrogen dioxide. I. Design, fabrication, and integration of the gas chromatography system

A miniature gas chromatography (GC) system was designed and developed using silicon micromachining and integrated circuit (IC) processing techniques. The micromachined gas chromatography (MMGC) system is composed of a miniature sample injector incorporating a 10-μm-long sample loop; a 0.9-m-long, rectangular-shaped (300 μm width and 10 μm height) capillary column coated with a 0.2-μm-thick copper phthalocyanine (CuPc) stationary phase, and a dual-detector scheme based upon a CuPc-coated chemiresistor and a 125-μm-diameter thermal conductivity detector (TCD) bead. Silicon micromachining was employed to fabricate the interface between the sample injector and the GC column, the GC column itself, and the dual-detector cavity. A novel processing technique was developed to sublime a homogeneous CuPc stationary-phase coating on the GC column walls. The complete MMGC system package is approximately 4 in, square and 100 mils (2.5 mm) thick, [96]