The measurement and analysis of a high gradient magnetic field for fine particle magnetophoresis

In this paper, theoretical and experimental analysis of high gradient magnetic fields has been performed to obtain the highest values of the force acting on submicron magnetic particles in magnetophoresis phenomena in microfluidic systems. The gradient magnetic field was obtained using ferromagnetic spheres placed in the air gap between NdFeB permanent magnets. The gaps for different intervals between the spheres were made with plastic rectangular channels. The magnetic field was measured with a specially designed portative magnetometer working on the 3D printer principle. A Hall probe G05 gaussmeter was used for the measurements. The magnetic field was measured and evaluated at different sphere radii and at different points with δ ≤ 0.1 mm steps. An approximate analytical method is used to determine the generated magnetic field and a simple empirical formula is obtained. This empirical formula is compared with experimental data and transformed into a simple form that can be easily used in the theoretical analysis and practical applications of magnetophoresis phenomena. According to the results obtained, the most favorable arrangement of the force acting on the magnetic particles in the fluid channels in magnetophoresis processes is evaluated.