Investigation of the Effect of Flow Dynamics and on-chip Magnet Distance on Magnetic Particles in Microfluidic Channels

This study explores the dynamics of magnetic microparticles in a magnet-integrated microfluidic chip, examining the effects of magnet distance and flow rate on particle motion. The integrated system enables compact, on-chip magnetophoresis for separating biologically important molecules and microorganisms. Experiments used Neodymium (NdFeB) magnets positioned at 10, 11, and 12 mm from the channel and flow rates of 0.5, 0.7, and 1 μl/min. At 10 mm, the magnetic field strongly influenced particle motion, causing accumulation near the channel walls, especially at lower flow rates. As the distance increased, drag forces dominated, reducing magnetic control. The highest particle accumulation (14.94%) occurred at 10 mm with a 0.5 μl/min flow rate, while the highest percentage of particles exiting the upper outlet (60.18%) was observed at 11 mm with 0.7 μl/min. These findings provide insights into the interplay between magnetic fields, hydrodynamic forces, and particle dynamics in microfluidic environments. They have potential applications in targeted drug delivery, diagnostics, and lab-on-a-chip technologies, where precise particle control is crucial for optimizing performance.