Influence of the internal gas flow distribution on the efficiency of a μ-preconcentrator

Preconcentration is an important analytical technique that will be crucial to the success of many detector systems. In this paper, we present a study on the effect of the internal gas flow distribution within a μ-preconcentrator. It leads to a significant enhancement of the concentration factor of the device.The miniaturized preconcentrator is targeted to benzene detection and is fabricated with silicon technology. The unit consists of a micro-heater surrounded by an insulating membrane. The preconcentrator is made up of a grid of suspended silicon bars underneath a polysilicon resistor. The silicon grid allows holding a large amount of adsorbent materials (Carbopack X) and provides efficient heat diffusion with less than 600 mW at a working temperature of 250 °C. A series of tests were conducted in this study to evaluate the influence of the gas flow distribution through the μ-preconcentrator. Results showed that by optimizing the gas-flow through the device the preconcentration factor can be increased with 85%, without increasing the complexity of the adsorption system.