(181f) Dynamic Separation of Magnetic Nanoparticles In a Microfluidic System with Different Flow Conditions

Controlled magnetic-field based separation of molecules in microfluidics systems has been the focus of attention in recent years due to their vast applications in immunological assays, disease diagnosis and biomedical research. Therefore, studies on the development of numerical models and their comparison with experiments of controllable separation of magnetic nanoparticles in microfluidics systems are of great interest and are actively been pursued. In this work, both experimental and computational results on the separation of magnetic particles are discussed.

The experimental part of this work involves the synthesis of nanoparticles, the fabrication of microsystems and the analysis of the system under the influence of magnetic fields with different flow conditions. The nanoparticles used in this study are particles of magnetite, synthesized by the coprecipitation method. Naked Fe₂O₃-Fe₃Onanoparticles were covered with a thin shell of silica using the well-known method developed by Stöber in order to study core-shell nanoparticles in the microfluidics system.  The silica-modified (hematite-magnetite) nanoparticles were then functionalized with a silane monolayer. Finally due to the importance of gold surface in biological funtionalization, core-shell nanoparticles of Fe₃O₄@SiO₂@Au were used in this work. The nanoparticles samples are characterized by X-ray diffraction (XRD), Dynamic Light Scattering (DLA), Zeta potential, Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM), and Magnetic susceptibility.

In the computational section of this work, we have simulated the magnetic-field based separation of the nanoparticles using a multi-physics finite-element method to predict the motion and capture of the magnetic nanoparticles as a first approximation. We also have simulated the system as a discrete mixture of magnetic nanoparticles in a continuos media. The simulations have been done in two different geometries and with different flow conditions. The position and angle of the magnet have also been examined.

The simulation and experimental results are compared in order to analyze the distribution and the efficiency of the separation of the magnetic core-shell nanoparticles. The results show that the models developed in this study could be useful in assisting the design of magnetic-field based separation Microsystems with potential applications on medical diagnosis.