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Microfluidic Device for DNA Dynamics in Mixed Flows

Susan J. Muller, University of California Berkeley, and Eric S.G. Shaqfeh, Stanford
Highlight from Stanford MRSEC 0213618

Lab-on-a-chip devices that are capable of performing microanalytical testing must have the capacity to precisely control the flow of very small volumes of fluid. The typical approach to this involves microfluidic devices in which the flow channels are of the order of 50 to 100 microns in diameter. Of particular interest in CPIMA has been the use of microfluidic devices that could be used to create flow conditions for capturing and orienting biomolecules that are sufficiently long that they may be visualized with optical microscopy. The prime model system for such experiments has been double-stranded DNA, which could achieve lengths of the order of tens of microns. In recent work, Muller and Shaqfeh have developed microfluidic devices and sequence-specific probes for studies of DNA hybridization kinetics that may also allow DNA genotyping with unprecedented read lengths. One particular device developed in CPIMA is a novel microfluidic four-roll mill that allows all flow types (from extension to shear to rotation) to used to examine DNA tumbling in mixed flows. The figure shows (a) the four-roll mill design, (b) images of ’¬-DNA in partially rotational flow (left side) and purely rotational flow (right side), and (c) master curves of dimensionless tumbling period in the rotational flow regime. Brownian dynamics simulations (open symbols) and experimental observations (closed circles) are in good agreement. Seed project linked to IRG-2.