An all-silicon microfabricated gas chromatographic column with a high aspect ratio

Increasing the aspect ratio of the microchannels of microfabricated gas chromatographic columns (μGCCs) can allow analytes to quickly reach equilibrium between the stationary phase and mobile phase , which helps improve their separation performance. In this paper, an all-silicon microfabricated gas chromatographic column (AS-μGCC) with a high aspect ratio was proposed and fabricated using deep reactive-ion etching (DRIE) and silicon direct bonding. Two AS-μGCCs with the lengths of 2 m and the aspect ratios of 6.6 (100 µm-width × 660 µm-depth) and 25 (30 µm-width × 750 µm-depth) were successfully fabricated. The effects of different aspect ratios on the column efficiency of AS-μGCCs were studied. A separation experiment showed that the column efficiency of the AS-μGCC with an aspect ratio of 25 (AS-μGCC-25) was 12 times higher than that of the AS-μGCC with an aspect ratio of 6.6 (AS-μGCC-6.6). The column efficiency of the AS-μGCC-25 was 1961 plates/m, and a heavy hydrocarbon mixture (C8–C20) could be separated using AS-μGCC-25 within 4.5 min