Innovative Design and Modeling of a Micromixer: Navier-Stokes and Convection-Diffusion Equations

A micro mixer is a micrometric device capable to obtain a uniform distribution from several components of a mix. Such components can be fluids with different concentrations coming into the micro mixer and, by electro osmotic effects and physical perturbations on their path, are mixed forming another fluid with uniform density at the outlet. Some of their applications appear in biochemical micro-laboratories (lab-in-chip). Physical laws modeling a micro mixer are those of fluid mechanics (Navier-Stokes eqs.), as well as the convection-diffusion equation for current density and concentration. Velocity of fluid and electric field are related by means of the Helmholtz-Smoluchowski equation which is used to set certain boundary conditions. This paper presents two innovative designs of a micro mixer following electro osmotic principles in a geometry with obstacles for the fluid. Furthermore, known reports from literature are verified to validate the mathematical method and to do a comparison and appreciate the advantages of the proposed designs.