Multiple-stage microfabricated preconcentrator-focuser for micro gas chromatography system

The design, fabrication, and characterization of a multiple-stage Si microfabricated preconcentrator-focuser (μPCF) for a micro gas chromatography (μGC) system that can provide real-time quantification and identification of complex organic vapor mixtures are presented. The μPCF consists of a Si microheater loaded with Carbopack B, Carbopack X, and Carboxen 1000 carbon adsorbent granules, and a Si micromachined cover plate. Deep reactive ion etching is utilized to produce mechanically robust fluidic interconnection adapters hermetically sealed to fused silica capillary tubing for connection to the other components in the μGC. This three-stage device is designed to capture compounds spanning up to 4 orders of magnitude in volatility. The dead volume, thermal mass, heating efficiency, and pressure drop of the three-stage μPCF are improved significantly over its single-stage μPCF predecessor. We demonstrate the successful capture, desorption, and high-resolution chromatographic separation of a mixture of 30 common organic vapors using our three-stage μPCF in a conventional GC system. The peak width at half height is <2.05 s for all compounds after elution from the GC column.