Transport of biomolecules in the Ratcheting Electrophoresis Microchip (REM)

Ratcheting electrophoresis microchip (REM) is a novel concept of a microfluidic device proposed by the authors for the electrophoretic separation of macromolecules such as DNA and proteins in aqueous solution. In the present report, a new type of REM is proposed. The first prototype of the REM, which consists of a microchannel and an array of thousands of parallel linear microelectrodes with a width of ∼ 2 μm and a pitch of ∼ 10 μm embedded in the wall of the microchannel, has some problems: dispersion of analyte molecules is large when they leave the surface of the electrodes in the direction parallel to the surface, and the small width of the microelectrodes that are needed to minimize the dispersion of molecules makes the chip susceptible to the Debye screening. To solve these problems, the crosswise migration type is proposed here, where electrophoretic migration is driven as crossing the microchannel, which results in minimized dispersion of analyte molecules and effective electric field over the whole channel that is free from the Debye screening. Computational simulation has been performed and satisfactory results were obtained.