Simulation of Particle Trajectory Under Laminar Flow for MDDS Application

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Magneticdrug delivery systems (MDDS) can be used to increase drug concentration and reduce side effects on healthy tissues by guiding magnetic drugs to specific areas via an external magnetic field. To understand the behavior of the magnetic drugs under magnetic field in MDDS application, this study proposed a multi-physics calculation model (including: magnetic force, drag force, buoyancy, and gravity), and validated the predictions through actual observations under various flowing parameters in a fluidic channel by digital optical microscope. In the validation experiments, the flow rate (0.5-2 mm/s), channel width (1.8 mm), and viscosity (8.75 cP) referring to a vein were considered. The results showed that the average trajectory error was 1.72 μm (z axis)/mm (x axis) with the flow rate (0.5 mm/s), which signified that our model has a high degree of reliability. This research also discussed the computational results of Nd-Fe-B permanent magnets (PM) and Y-Ba-Cu-O bulk superconductors (HTS) for attracting particles of different sizes in veins. The results showed that when the magnetic field source was placed at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> = −11 mm and the flow rate was 1 mm/s, the critical particle size of PM was 1 μm, and that of HTS was 0.5 μm; when the magnetic field source position was at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> = −6 mm, the critical particle sizes of HTS and PM were reduced to 0.3 μm and 1 μm, respectively, showing that stronger magnetic field strength and gradients can attract smaller magnetic particles. In addition, for HTS and PM, the particles were attracted in the range of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> = −5 mm to 5 mm and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> = −9 mm to −1 mm, indicating that HTS can concentrate particles more effectively because of its large magnetic field gradient in the center.