CFD design of a microfluidic device for continuous dielectrophoretic separation of charged gold nanoparticles

Abstract

Separation of biological as well as, non-biological nanoparticles have primarily been done by trapping, which has to be carried out in a batch mode. Continuous separation would not only increase the throughput but would be less cumbersome. In the present work, therefore, a new design of a microfluidic device for continuous separation of charged metal nanoparticles (gold) by dielectrophoresis (DEP) has been proposed. The effect of the electrical double layer (EDL) on the DEP separation has also been considered in this study. The effective complex permittivity of the neutral particle is estimated using the multishell model, which takes into account the complex permittivities of both the charged particle and the EDL. Microelectrodes of unequal size are embedded on the vertical side walls to generate a non-uniform electric field along the width of the microchannel. Size separation of nanoparticles takes place based on the DEP force experienced by them. Computational fluid dynamic simulations have been carried out to optimize the design and process parameters for continuous separation, by negative DEP, of charged gold nanoparticles of size 30 nm and 60 nm. Sensitivity analysis has also been carried out to study the effect of different parameters on the separation efficiency for the proposed design.