Presentazioni e Articoli Tecnici

This work presents a two-dimensional multiphysics model developed in COMSOL Multiphysics® to investigate magnetically influenced particle transport through a tubular flow system. The study is a proof-of-concept for a potential biomedical sensing approach in which magnetically responsive particles, representing pathogen–antigen complexes, are transported through a fluidic channel under the influence of an external magnetic field. The computational domain consists of a cylindrical tube embedded within a larger air region. Square inlet and outlet boundaries are defined at each end of the tube, and a rectangular permanent magnet is placed adjacent to the right side of the channel, with explicitly defined north and south poles. The surrounding domain is modeled as air to provide realistic open-boundary electromagnetic behavior. The magnet is assigned an N52 sintered permanent magnet material. A third material representing “SpiroTech amino acid beads” is introduced as discrete particles at the inlet, with neutral charge, 3 μm diameter, and an effective magnetic flux density norm of 1.4 T. The model couples three physics interfaces: Magnetic Fields, Laminar Flow, and Particle Tracing for Fluid Flow. The Magnetic Fields interface is applied to the full domain to compute the spatial distribution of the magnetic flux density generated by the permanent magnet. Free-space conditions are used in air regions, with insulation conditions applied at the external boundary. The resulting magnetic field is used to compute a Maxwell stress tensor-based force, which is incorporated into the fluid model as both a body force and a pressure contribution at the inlet. The Laminar Flow interface governs incompressible air flow through the tube, with no-slip conditions along the walls. Inlet and outlet pressures are defined using a magnetic-field-dependent expression derived from the Maxwell stress tensor formulation. Fluid properties correspond to air, and the resulting velocity field is fully coupled to particle transport. Particle motion is modeled using the Particle Tracing for Fluid Flow interface. Particles are released at the inlet and are subjected to Stokes drag based on the local velocity field, as well as a magnetophoretic force derived from the magnetic field gradient. Outlet boundaries allow particle exit, while freeze conditions prevent artificial re-entry. Particle trajectories are solved in a time-dependent study using stationary magnetic and flow solutions. The simulation is performed in two steps: a stationary study for the magnetic field and flow solution, followed by a time-dependent particle tracing simulation. Results show that particle transport is accelerated in regions influenced by magnetic-field-induced pressure changes, with observable trajectory deflection toward the magnet-adjacent side of the channel. Overall, this model demonstrates a coupled multiphysics framework for magnetically assisted particle transport in a simplified tubular system. The results suggest that magnetic field gradients can meaningfully influence both fluid flow and particle trajectories, providing a basis for future development of magnetically controlled biosensing and diagnostic transport devices.