Magnetic Bead Separation from Flowing Blood in a Two-Phase Continuous-Flow Magnetophoretic Microdevice: Theoretical Analysis through Computational Fluid Dynamics Simulation

The use of magnetic particles has recently expanded for a process. known as detoxification, in which different toxins and microorganisms are captured from the bloodstream of septic patients. Due to the magnetic properties of the particles, once the capture of the pathogens is complete, their separation from the patient's blood can be performed in a continuous process using an external magnetic field. In this work, we introduce a design for a two-phase continuous-flow microseparator and present an optimization study for the separation of magnetic beads using state-of-the-art-computational modeling. The developed numerical method includes a combination of magnetic and fluidic computational models that accurately describe the magnetophoretic motion of the beads. To the best of our knowledge, this is the first computational study of the interaction between two different fluids flowing simultaneously in the device (blood water) that takes into account two-way coupled particle fluid interactions in the flow field as well as the effects of the particles' motion as they cross the interface between the fluids under various magnetic field intensities. For optimization purposes, a dimensionless number J is introduced, and our results show that complete and safe separation is achieved only for a certain range of this parameter (0.2-0.3). Overall, the modeling effort enables understanding of the fundamental physical phenomena involved in the separation process, while offering an ideal parametric analysis and optimization platform, thereby facilitating the development of novel magnetophoretic microsystems not only for blood detoxification processes but also for many other biomedical applications that involve multiple confined liquid phases.