ANYL 131 |
| This work investigates the use of Raman confocal imaging to study chemical reactions and diffusion processes in microchannels. The current methods used to study these phenomena in microfluidic chips usually involve fluorescence techniques, the diffusion of a probe, or the production of a probe by a complexation reaction. However, these techniques cannot be applied to the majority of chemical reactions, whose products and reactants do not display fluorescent properties. Nor can these techniques be used to characterize the interdiffusion of two solvents since fluorescence microscopy requires the addition of dyes. In the present work, we use Raman confocal microscopy to address these microscale phenomena. Raman imaging is a non-intrusive technique that gives the local concentrations of various chemical species in a confocal volume of micrometer size (1-5 µm3). The geometry of the microchannels used throughout the experiments are Y-shaped systems. The liquids being studied are injected at a constant flow rate in the two arms of the chip. At these small length scales, the two liquids mix only by molecular diffusion. We have then measured Raman images of the interdiffusion zone of several miscible non-reacting solvents (HCCl3/H2CCl2,DMSO…), and reacting liquids (H2O/D2O). Using models that take into account the difference in viscosities, we were then able to estimate the interdiffusion coefficients during these reaction-diffusion processes. |
|
General Papers
7:00 PM-9:00 PM, Sunday, 28 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Analytical Chemistry |