Design and simulation of micromixers for efficient antigen-antibody binding

Abstract

Microfluidic systems have gained more attention, especially in the past decade due to technological improvement in this area. They have become an important tool for clinical analysis and spread to other areas to be used for different purposes. Microfluidic systems have been utilized for various applications such as drug delivery, clinical diagnostics, biomedical engineering, etc. They offer substantial advantages including low reagent consumption, fast analysis, and high sensitivity of detection. Fluid flow in the microchannel is laminar and dominated by molecular diffusion due to small Reynolds numbers of the fluids resulting in insufficient mixing. Enhanced mixing is required in most applications dealing with biological samples. To improve mixing, generally active or passive micromixers are used. Active micromixers require external energy sources such as dielectrophoresis, and electrokinetic disturbance which make the fabrication complicated while passive micromixers do not require any external energy sources. For this reason, passive micromixers are preferred due to their ease of fabrication and simple operation. In this study, in order to enhance mixing, passive micromixers with varying geometries have been designed and a fluid flow pattern has been simulated using COMSOL Multiphysics software. Antigens and antibody-modified magnetic beads were fed through two different inlets with varying channel geometries. The inlet channel geometry for the magnetic beads is expected to result in the formation of vorticities and disturbance of the fluid flow, causing the dispersion and rotation of the magnetic beads, which will help increase the binding efficiency of antigens onto the surface of antibody-modified magnetic beads. Moreover, the proposed micromixer geometries will cause hydrodynamic interactions between antigens and antibody-modified magnetic beads when they flow through the channel which enhances mixing. According to COMSOL simulation results, serpentine, and convergence-divergence type, micromixers resulted in good mixing of different fluids. To verify simulation results experimentally, some of the designed microfluidic systems giving the best simulation results were fabricated and tested.