Numerical simulation of DNA sample preconcentration in microdevice electrophoresis

A numerical model is presented for the accurate and efficient prediction of pre-concentration and transport of DNA during sample introduction and injection in micro-capillary electrophoresis. The model incorporates conservation laws for the different buffer ions, salt ions and DNA sample, coupled through a Gaussian electric field to account for the field modifications that cause electro-migration. The accuracy and efficiency required to capture the physics associated with such a complex transient problem are realized by the use of the Finite Element - Flux Corrected Transport (FE-FCT) algorithm in two dimensions. The model has been employed for the prediction of DNA sample pre-concentration and transport during electrophoresis in a double-T injector micro-device. To test its validity, the numerical results have been compared with the corresponding experimental data under similar conditions, and excellent agreement has been found. Finally, detailed results from a simulation of DNA sample pre-concentration in electrophoretic microdevices are presented using as parameters the electric field strength and the other species concentrations. The effect of the TRIS concentration on sample stacking is also investigated. These results demonstrate the great potential offered by the model for future optimization of such microchip devices with respect to significantly enhanced speed and resolution of sample separation