Width-modulated microgas chromatography separation columns with silica nanoparticles stationary phase

Microgas chromatography separation columns typically employ channels with fixed cross sections. In this article, we demonstrate unidirectional microfabricated width-modulated columns (μWMC) that afford improved chromatographic efficiency, resolution and retention times compared to corresponding constant width bidirectional columns. The width of 1m-long, 250 μm-deep μWMC is gradually reduced from 120 μm to 20 μm at 1 μm/cm. The effect of inlet selection (120 μm or 20 μm) on chromatographic performance is also evaluated. Moreover, with our improved fabrication process, multiple serially connected devices are simultaneously coated for the first time with highly-stable silica nanoparticles utilizing layer-by-layer technique thus enabling constant film thicknesses.