DNA separation is ubiquitous in biological research. The common technique for performing these separations, gel electrophoresis, leaves much to be desired. The separations are slow, taking hours to separate. There can also be huge variations in quality between gels, due to the randomness of the gel. Gels are limited to DNA smaller than about 15 kbp, unless pulsed fields are used that take even longer to separate. Performing these separations in microfluidic devices overcomes some of these problems. Two common geometries used to separate DNA are the slit-well geometry and the post array geometry. Using the understanding gained using these geometries, researchers have been able to create continuous separation devices.We have tested novel operations modes, initially predicted by theory and simulations, within these well understood geometries. We achieved bi-directional migration using an asymmetric pulsed electric field in the slit well geometry. This created a non-clogging DNA filter. We achieved improved separation in a hexagonal post array by rotating the array. We were able to separate DNA in a shorter array, 4 mm, and at a higher electric field, 50 V/cm, than seen before. We also tried to create a continuous DNA separation device using proximity field nano-patterning, but were ultimately unsuccessful. While the work done to develop microfluidic DNA separation devices by a multitude of researchers ultimately did not change how DNA separations are performed in biology labs, the advances and insights gained from those performing the work led to great advancements in DNA manipulation techniques, including genomic and sequencing techniques. In fact, a genomic technique called DNA barcoding, which is performed by stretching DNA in very small channels, or nanochannels, would not have been possible without the initial microfluidic work in DNA separation techniques.
University of Minnesota Ph.D. dissertation. June 2014. Major: Chemical Engineering. Advisor: Kevin David Dorfman, David J. Norris. 1 computer file (PDF); x, 122 pages.
Thomas, Joel Daniel Pierson.
My adventures in microfluidics: exploration of novel modes for sized-based DNA separation.
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