Collection of magnetic particles from synovial fluid using Nd-Fe-B micromagnets

In this paper, the collection of magnetic particles from synovial fluid using Nd-Fe-B micromagnets is quantitatively studied to determine the influence of fluid viscosity and magnet geometry on the velocity distribution and collection rate. Magnetic capture is validated in highly viscous fluids, such as bovine synovial fluid (η~ 1 Pa·s). A first-order theoretical model has been developed to predict the particle motion, as well as a numerical multiphysics model. Both models exhibit good agreement with in vitro experimental magnetic collection results. The velocity of the magnetic particles is shown to be inversely proportional to fluid viscosity, and two magnetic structures are compared in term of collection efficiency: a cylindrical Nd-Fe-B permanent magnet and a laser-machined conical Nd-Fe-B permanent magnet.