Gas chromatography (GC) is one of the most widespread techniques used in laboratories as a way to separate and analyze complex mixtures of volatile and semi-volatile compounds. The main advantage of miniaturization of these systems is the increased performance due to the reduced time for analysis and reduced fabrication cost of the complex pneumatic flow system. In this paper advanced design ideas and fabrication processes to facilitate integration of the sample concentrator and the column will be presented. Using the LIGA process, 0.5-and 2-m-long, 50-lm-wide, and up to 600-lm-high aspect ratio metal GC separation columns with on-chip integrated sample injection and detection were fabricated. Initial experiments of coating these high aspect ratio columns show promising results when compared to simple tubular columns.

The size evolution of gold nanoparticles in a millifluidic reactor is investigated using spatially resolved transmission electron microscopy (TEM). The experimental data is supported by numerical simulations, carried out to study the residence-time distribution (RTD) of tracers that have the same properties as Au ions. Size and size distribution of the particles within the channels are influenced by the mixing zones as well as the RTD. However, the Au nanoparticles obtained show a broader size distribution even at the shortest investigated residence time of 3.53 s, indicating that in addition to surface growth reaction kinetics also plays an important role. The comparison of time resolved particle growth within the millifluidic channel with flask-based reactions reveals that the particle size can be controlled better within millifluidic channels. Overall, the results indicate potential opportunities to utilize easy to fabricate millifluidic reactors for the synthesis of nanoparticles, as well as as for carrying out time resolved kinetic studies.

High aspect ratio nickel microfluidic columns were fabricated using the LiGA technique. The 2-m-long 50-m-wide high aspect ratio columns will be the separation component of a handheld gas chromatograph device for detecting semivolatile and volatile compounds. As a first step, 600-m-deep electrodeposited nickel columns were fabricated. The serpentine columns were sealed and pressure-flow rate characteristics compared with the theoretical values. The response of the sealed columns was studied by running methane gas plugs through uncoated columns with a flame ionization detector at the exit. Negligible flow-induced dispersion was observed in the sealed metal columns. Unretained peak widths of 15 ms were measured, and the experimental pressure and flow rate distributions matched those predicted by established analytical models within 2.5%. Columns were coated with OV-1 stationary phase using static coating methods. A mixture of four hydrocarbons C 6 , C 8 , C 10 , and C 12 was separated in a coated 50 m by 600 m by 0.5 m column in less than 2 s at 70 C.[ 2006-0020]Index Terms-Fast gas chromatography, LiGA, micro gas chromatograph (GC), X-ray lithography.

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Micro gas chromatograph (GC) separation columns were fabricated and tested. Rectangular columns with high aspect ratio have inherent benefits over traditional tubular columns and can easily be integrated into a GC sensor system for rapid chromatographic analysis. The 2 m long, 50 μm wide, 500 μm tall columns were fabricated out of electroplated nickel through deep X-ray lithography using the LIGA technique. Critical fabrication issues including reproducible fabrication of compact footprint, deep columns and sealing of the metal columns were addressed. Experiments were conducted to establish the relationship between column head pressure and flow rate. Methane samples analyzed using hydrogen as a carrier gas on uncoated columns showed very little dispersion suggesting that there was no internal leakage in the columns. The sensor performance data compares well with other micro GC sensor systems.