Three-dimensional molecular mapping in a microfluidic mixing device using fluorescence lifetime imaging.

Fluorescence lifetime imaging (FLIM) is used to quantitatively map the concentration of a small molecule in three dimensions in a microfluidic mixing device. The resulting experimental data are compared with computational fluid-dynamics (CFD) simulations. A line-scanning semiconfocal FLIM microscope allows the full mixing profile to be imaged in a single scan with submicrometer resolution over an arbitrary channel length from the point of confluence. Following experimental and CFD optimization, mixing times down to 1.3+/-0.4 ms were achieved with the single-layer microfluidic device.