Evaluation of Continuum Mechanics for Electroosmotic Flow in Nanosize Structures

Development of nano-devices for various applications has drawn great attention recently driven by the need of miniaturizing the devices for the integration and automation of Biochips or Lab-on-a-Chip devices. Fundamental understanding of transport phenomena in nanofluidic channels is critical for systematic design and precise control of such devices. The goal of this study is to develop a theoretical model to study electroosmotic flow in nanochannels. Instead of using the Boltzmann distribution, the conservation condition of ion number and the Nernst equation are used in this new model to find the ionic concentration field in the nanochannels. A correct boundary condition for the concentration field at the wall of the channel is developed and the symmetry condition of the potential field at the center of the nanochannel is applied to this model. The ionic concentration field, electrical potential field and flow field are obtained by numerically solving this model. Comparisons of area-average velocity between the numerical simulations and experimental results reported in literature are provided.