MICRO-FLOW ANALYSIS BY MOLECULAR TAGGING VELOCIMETRY AND PLANAR RAMAN-SCATTERING

摘要

The two dimensional Molecular Tagging Velocimetry (2D-MTV) was used to measure velocity fields of the flow in a micro mixer. Instead of commonly used micro particles an optical tagging of the flow is performed by using a special dye. The flow induces a deformation of the optically written pattern that can be tracked by laser induced fluorescence. The series of raw images gained this way were analyzed and quantified by the "method of the optical flow". Reference measurements have been carried out to allow conclusions about the accuracy of this procedure. In addition a quantitative visualization of concentration fields of different fluids that participate in the mixing process of a microfluidic system was enabled by Planar Spontaneous Raman Scattering (PSRS). It was utilized that different species of molecules are distinguishable from another by their characteristic "spectral fingerprints" (their Raman spectra). The Raman stray light of the relevant species was spectrally selected by a narrow bandpass filter and thus detected unaffectedly by the Raman stray light of other species. The successful operation of this measurement procedure in micro flows will be demonstrated exemplary for a mixing process of water and ethanol.