Numerical simulation study on microfluidic particle separation based on magnetophoretic force

Rapid blood sample pretreatment is critical for early bloodstream infection diagnosis, yet direct pathogen extraction is hindered by scarce target microbes and abundant blood cell interference. This work develops a 3D magnetophoretic microfluidic separator to continuously isolate magnetically tagged white blood cells from unlabeled pathogens. Its core innovation integrates periodically grooved microchannels with aligned permanent magnets to amplify transverse magnetic gradients and boost lateral particle deflection. A COMSOL multiphysics model coupling laminar flow, magnetic fields and particle tracking is built to analyze flow, magnetic force and particle motion. Under inlet velocity 75 µm s^-1 and remanence 0.02 T, non-magnetic particles attain 97.04% separation yield at the target outlet, while magnetic particles drift toward high-gradient zones under dominant magnetophoretic force. Separation efficiency varies non-monotonically with particle size and density, peaking at 83.56% for 4 µm, 1800 kg m^-3 particles. Cuboid magnets outperform conical and spherical counterparts. This grooved channel-magnet array setup strengthens magnetophoretic deflection and offers a feasible scheme for microfluidic blood pretreatment and pathogen enrichment.