Time-Varying Magnetic Field to Enhance the Navigation of Magnetic Microparticles in a Bifurcated Channel

Abstract

This letter investigates the navigation of magnetic microparticles (MMPs) in a Y-shaped microfluidic channel under the influence of an external magnetic field. The external magnetic field exerts a magnetic force on the magnetizable MMPs to steer them from the bifurcation point to the desired channel. During this process, some MMPs aggregate and stick to the channel walls, thus reducing the efficacy of the navigation process. To mitigate this problem, a time-varying magnetic field (TVMF) is applied for efficient navigation of the MMPs in the channel. The TVMF alternately switches between two modes of operation described as follows. In the first mode of operation, the TVMF is applied for a certain time duration to generate the magnetic force required for steering the MMPs to the desired outlet. The second mode of operation facilitates mitigation of the stiction and aggregation of MMPs by modulating the TVMF and time duration of operation, so as to yield a lower magnetic force in the reverse direction to that in the first mode. Extensive simulations are performed to analyze the switching time for effective steering of the MMPs using COMSOL Multiphysics. Results illustrate that the time duration between the two modes of operation should be set using a ratio of 3 $:$ 1 for effective guidance of the MMPs to the correct outlet.