DNA Electrophoresis in Sparse PDMS Micropillar Arrays

The separation of long DNA by electrophoresis through regular arrays of micropillars is a major accomplishment of microfluidics, with the potential of reducing day-long macroscale separations into the minute range. We will present new experimental data obtained for the transport properties of lambda-phage DNA (48,500 base pairs) in model post arrays. The devices are fabricated in PDMS, featuring centimeter-long hexagonal arrays of 1 micron posts with pitches of 3, 5 and 7 microns. We have implemented a robust method for fabricating and preparing these chips that allows for high chip-to-chip reproducibility and reusability. We will present results on the mobility and dispersivity of lambda-DNA as a function of the pitch of the array and the electric field. These data will be compared with prevailing theories of DNA electrophoresis, including continuous-time random walk predictions and the so-called “channeling” effect that is predicted by simulations of DNA electrophoresis in sparse, ordered arrays.