Sub-ppm gas sensor detection via spiral μ-preconcentrator

In the present work, a silicon-based preconcentrator is proposed and developed, which consists of a spiral-shaped micro-preconcentrator followed by a mu-hotplate sensor matrix. The shape of the preconcentrator was chosen according to technological and gas-flow limitations as it is required that the whole gas flow passes through the adsorbent in order to obtain a good concentration factor. Therefore, a spiral-shaped configuration was adopted with a 10-cm length, and a width/depth of 300 mu m. In this case, the carrier flow is high enough to avoid stagnation but provide a fast evacuation of the gas after applying a thermal desorption pulse. The proposed spiral mu-preconcentrator leads to a robust and highly integrated device able to be incorporated in a GC/MS-gas sensor system. (C) 2008 Elsevier B.V. All rights reserved.