Capturing Magnetic Nanoparticles with Different Permanent Magnet Shapes in a Microchannel System

Abstract

This study examines the influence of different permanent magnet geometries (cube, ring, disc, and Halbach array) on capturing magnetic fluorescent nanoparticles (Synomag,70m) for magnetic drug delivery. Magnetic flux density mapping was performed with a custom setup using a 3MTS Teslameter, ensuring precise magnetization profiling around each magnet. A calibration curve for fluorescence intensity developed through regression analysis of Synomag nanoparticle concentrations, enhanced imaging accuracy. Python line profiling revealed that the Halbach array achieved the highest capture efficiency, reaching a concentration of 10 mg/ml, compared to 5.7 mg/ml for the cubic, 4 mg/ml for the disc, and 2 mg/ml for the ring magnet, under a flow velocity of 10 mm/s. Our results highlight the critical role of magnet design in magnetic nanoparticle capture and distribution, with the Halbach array excelling in high-concentration applications and cubic/disc magnets favoring even distribution. The Halbach array likely excels because it creates a high magnetic field strength and a steep gradient (?B) in the region near its surface. This combination ensures efficient particle capture by balancing the drag forces from the fluid flow with a localized, focused magnetic force, making it highly effective in the given flow configuration.