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Type of Document Thesis Author Somanchi, Sharad Kumar Author's Email Address shark_bits@yahoo.com URN etd-12282004-125516 Title Velocity Imaging in Polymer Based Microfluidic Systems Degree Master of Science Department Chemical Engineering, Department of Advisory Committee
Advisor Name Title Dr.Oliver Steinbock Committee Co-Chair Dr.Ravindran Chella Committee Co-Chair Dr.Bruce R. Locke Committee Member Keywords
- Back flow
- Electro-osmotic flow
- Microchannels
- Flow Imaging
- Dispersion
- Taylor
- Aris
- Method of Moments
- PDMS
- Fluorescent dyes
Date of Defense 2004-11-17 Availability unrestricted Abstract Electro-osmotic flow, where an applied electric potential difference induces fluid motion, is extensively employed for fluid transport in microfluidic devices. In this thesis, we present a direct flow imaging method for characterizing the electro-osmotic velocity profiles in the polymer based microchannels by using a fluorescent tracer. Fluorescence microscopy was used as a tool for imaging the flow in these microdevices. The variation in the fluorescence intensity is plotted in space and time as the tracer moves along the microchannel under an applied external electric field. The transverse velocity profiles in the microchannel are obtained from these time-space plots. This direct flow imaging method provides a much simpler technique for characterizing the velocities with a good resolution, when compared to much complex methods that require use of sophisticated techniques and experimental setup. The postulated method is verified with theoretical studies and also with indirect flow imaging method. The measurement of volumetric flow rate and characterizing the velocity profiles in these microfluidic devices is important, as it forms a basis for the effective and precise control of fluid transport.
The thesis also presents the sample loading and dispensing operation, in a double T- microfluidic design, which is a widely used technique in capillary electrophoresis (CE). Further dispersion of the sample plug during dispensing operation in double T-design is studied and quantified using Taylor-Aris theory. The dispersion of fluorescent tracer is determined experimentally using the method of moments and verified with the Taylor-Aris model.
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