On the magnetic field architecture required to capture superparamagnetic nanoparticles in a microcapillary flow

Abstract

The magnetic field required for the capture of superparamagnetic nanoparticles flowing in a microcapillary array under a constant pressure regime was investigated in vitro. It was found that the nanoparticles were captured in locations that varied significantly in magnetic field strength, and that the location of capture was strongly related to the net volumetric flow through the microcapillary array. A hypothesis is presented to explain these data in which the magnetic field of the trapping Neodymium Iron Boron (NdFeB) block magnet is divided into two zones that act differently on the nanoparticles. In the first ‘steering zone’, nanoparticles are moved closer to the capillary wall where they can be captured downstream in the second ‘capture zone’. This hypothesis can be used in the future to design magnetic field shapes for more effective particle capture at higher flow rates with lower field strengths.