Fabrication and characterization of stop flow valves for fluid handling

Monolithic stop flow valves produced by Deep Reactive Ion Etching (DRIE) are proposed for the handling and the processing of small metered fluid volumes in capillary channels. A 2 /spl mu/l sampling unit has been successfully integrated as an element of a miniaturized chemical analysis system to improve analysis reproducibility. The net pressure needed to overcome the stop flow valve was determined experimentally for different valve diameters and compared to theoretical values. A 60 /spl mu/m diameter valve diameter can typically withstand a water pressure head of 20 cm, which is largely sufficient for most applications. Sampling of 2 /spl mu/l of selection of solvents was successfully demonstrated.