Metrology and Simulation of Chemical Transport in Microchannels

We are working towards building a CAD tool (NetFlow) for microfluidic systems. To support the development of this tool, diffusion and flow experiments are being performed in microchannels. In this paper, we describe the novel flow visualization approach developed for these experiments and report experimental results and corresponding simulations for fluid transport in microchannels. The experimental approach relies on the use of a caged, charged fluorescent dye which can be activated (uncaged) by a UV laser beam and tracked by fluorescence imaging [1]. In contrast to standard methods for inserting a dye plug in a microchannel, this is the only technique which allows definition of very precise regions at any place along the channel. Specifically, this allows a narrow definition of starting plugs and therefore an improved determination of the flow profile. We have used this technique to study diffusion, pressure-driven flow, and electrokinetic flow in various microchannel geometries.