Silicon micromachined gas chromatography system with a thin-film copper phthalocyanine stationary phase and its resulting performance

• Published in: Surface & coatings technology Vol. 68; pp. 679 - 685
• Main Authors: Koselar, Edward S., Reston, Rocky R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.1994
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/0257-8972(94)90237-2

A miniature gas chromatography (GC) system has been designed, fabricated and developed using modern silicon micromachining and integrated circuit (IC) processing techniques. The micromachined GC system is composed of a miniature sample injector that incorporates a 10 μl sample loop, a rectangular-shaped (width, 300 μm; height, 10 μm) capillary column, with a length of 0.9 m, coated with a copper phthalocyanine (CuPc) stationary phase (thickness, 0.2 μm) and a dual-detector scheme based on a CuPc-coated chemiresistor and a commercially available, thermal conductivity detector (TCD) bead (diameter, 125 μm). Silicon micromachining was employed to fabricate the interface between the sample injector and the GC column, the column itself and the dual-detector cavity. A novel IC thin-film processing technique was developed to sublime the CuPc stationary phase coating on the column walls that were micromachined in the host silicon wafer substrate and the Pyrex® cover plate, which were then electrostatically bonded together. The CuPc-coated chemiresistor was designed and fabricated using conventional IC processing techniques. The micromachined GC system can separate parts per million (ppm) ammonia and nitrogen dioxide concentrations when isothermally operated (55–80°C). With helium carrier gas and nitrogen diluent, a 10 μl sample volume containing ammonia and nitrogen dioxide injected at 40 lbf in -2(2.8 × 10 5 Pa) can be separated in less than 30 min.