DNA Migration and Separation on Surfaces with a Microscale Dielectrophoretic Trap Array

Abstract

We studied the surface migration of DNA chains driven by a dc electric field across localized dielectrophoretic traps. By adjusting the length scale of the trap array, separation of a selected band of DNA was accomplished with a scaling exponent between mobility and number of base pairs similar to that obtained in capillary electrophoresis. We then provided a model, which predicts the trapping and extension of DNA chains at a dielectrophoretic trap responsible for the surface mobility and separation.

Simulation of electrophoretic stretching of DNA in a microcontraction using an obstacle array for conformational preconditioning

“…In our device, the magnitude of E · ١E reaches as high as 1.4ϫ 10 7 V 2 / cm 3 which is only one order of magnitude smaller than that produced by Petersen et al 52 in their trapping work. But in contrast to our device, the large values of E · ١E that led to trapping were highly localized near the edges of the gold strips and only occurred over length scales of about 100 nm, comparable to the persistence length of DNA.…”

“…In our geometry, the strong fields and gradients exist over the entire length of the contraction which is ᐉ c =80 m, which is much larger than the radius of gyration of T4-DNA and comparable to its contour length. So T4-DNA molecules in our device could polarize over their entire dimension which could possibly lead to even stronger nonlinear electrokinetic effects than seen by Petersen et al 52 In addition, the fact that DNA molecules are stretched in the contraction could render them more polarizable than when they are in their coiled state, 55 further increasing their sensitivity to nonlinear electrokinetic effects.…”

“…Most studies on the dielectrophoresis of DNA have used ac fields and created the necessary electric field gradients by placing the electrodes in close proximity to each other. There have been a few studies, however, that have considered electrodeless dielectrophoresis of DNA using microfabricated devices to shape the field lines, [50][51][52][53] and some work has even been performed on dc fields. 52,53 Chou et al 50 and Regtmeier et al 51 used arrays of obstacles to bend and concentrate the field lines between the obstacles, and using an ac field, they trapped DNA between the obstacles.…”

“…This technique is similar to the previously proposed method of Ajdari and Prost 54 where ac dielectrophoretic traps transverse to a uniform dc field slow down DNA molecules in a size-dependent manner. Petersen et al 52 also adapted the method suggested by Ajdari and Prost by using thin strips of gold laid down perpendicular to a dc electric field. The periodic strips attracted the electric field lines due to their high conductivity and created strong dielectrophoretic forces in a highly localized area near the edges of the gold strips.…”

Simulation guided design of a microfluidic device for electrophoretic stretching of DNA

“…46 Moreover, electric field gradient at the expansion and contraction of the proposed devices might induce dielectrophoresis effect that could polarize DNA and result in unpredictable influence to DNA behavior. 43,47 To summarize, in order to have an affordable but useful prediction, we use coarsed-grained models that hopefully preserve the most important physics but only leave away the unimportant ones. From the reasonable agreement between the previous experiments 28,33 and simulations, 26,48 the FEM-BD simulations used here should be capable to catch the behavior of the DNA in microfluidic devices.…”