Study of miscible and immiscible flows in a microchannel using magnetic resonance imaging.

Magnetic resonance imaging (MRI) is a noninvasive technique that can be used to visualize mixing processes in optically opaque systems in up to three dimensions. Here, MRI has been used for the first time to obtain both cross-sectional velocity and concentration maps of flow through an optically opaque Y-shaped microfluidic sensor. Images of 23 micromx23 microm resolution were obtained for a channel of rectangular cross section (250 micromx500 microm) fed by two square inlets (250 micromx250 microm). Both miscible and immiscible liquid systems have been studied. These include a system in which the coupling of flow and mass transfer has been observed, as the diffusion of the analyte perturbs local hydrodynamics. MRI has been shown to be a versatile tool for the study of mixing processes in a microfluidic system via the multidimensional spatial resolution of flow and mass transfer.