A novel micropreconcentrator employing a laminar flow patterned heater for micro gas chromatography

A simple micromachined process based on one photomask is developed for a novel micropreconcentrator (PCT) used in a micro gas chromatograph (GC). Unique thick silver heating microstructures with a high surface area for microheater of PCT are fabricated by combining the microfluidic laminar flow technique and the Tollens reaction within a microchannel. Silver deposition using this laminar flow patterning technique provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (>200 m). An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microchannel. The PCT can be heated to >300 °C rapidly by applying a constant electrical power of 1 W with a heating rate of 10 °C s ¹. Four volatile organic compounds, acetone, benzene, toluene and xylene, are collected through the proposed novel PCTs and separated successfully using a 17 m long gas chromatography column. The peak widths at half height (PWHHs) of the four compounds are relatively narrow (<6 s), and the minimum PWHH of 3.75 s is obtained for acetone. The preconcentration factors are >38 000 for benzene and toluene.