Effect of magnetic nanoparticles on magnetic field homogeneity

The mechanism of magnetic nanoparticles (MNPs) affecting magnetic field uniformity is studied in this work. The spatial distribution of MNPs in liquid is simulated based on Monte Carlo method. The induced field of the single MNP is combined with the magnetic field distribution of magnetofluid. In the simulation, magnetic field uniformity is described by a statistical distribution. As the chemical shift (CS) and full width at half maximum (FWHM) of magnetic resonance (MR) spectrum can reflect the uniformity of magnetic field, the simulation is verified by spectrum experiment. Simulation and measurement results prove that the CS and FWHM of the MR spectrum are basically positively correlated with the concentration of MNPs and negatively correlated with the temperature. The research results can explain how MNPs play a role in MR by affecting the uniform magnetic field, which is of great significance in improving the temperature measurement accuracy of magnetic nanothermometers and the spatial resolution of magnetic particle imaging.