Numerical Analysis of a Class of Active Electro-Kinetic Micro-Mixer by Applying Poisson- Nernst-Planck and Naiver-Stokes (PNP-NSE) Equations

Micro-mixers are vital components of “Lab-on-a-Chip” devices. Increasing the mixing quality and reducing the mixing time remains as an open challenge in their design. In this work, we study some of the effects of the positioning of the electrodes on the enhancement of the mixing efficiency and reduction of mixing time. To approach the real physics of electro-osmosis and capture the phenomena at the AC electrodes, we numerically solve inter-coupled Poisson Nernst-Plank–Naiver-Stokes equations (PNP-NSE system of equations) using an in-house code (Rayan). In contrary to other approximate low-cost models like traditional Poisson-Boltzmann (PB) model, PNP-NSE model can capture electro-migration and ion convection on charge density redistribution. For the first time in the open literature, we present the installation of the electrodes on the vertical walls of the mixing chamber. Using this vertically mounted electrodes we were able to reach to a mixing efficiency of 99% without increasing mixing time. .