MPI of soft ferromagnetic needles

The combination of magnetic particle imaging with magnetic actuation is a promising additional application of MPI field generators aside from the imaging of SPIO tracers, because similar field configurations are needed. Since ferromagnetic materials can be manipulated easily using magnetic fields, the MPI properties of these materials are of interest to achieve a good combination of both functionalities. This work investigates the MPI signal of needle-like soft ferromagnetic objects as markers for tracking magnetic devices. Our results confirm the influence of demagnetization fields on the magnetization curve of macroscopic ferromagnetic objects and the importance of aspect ratio for the strength of the MPI signal. In addition, the spatial encoding properties of the system function are evaluated. The results show that the localization of ferromagnetic needles is possible but only in the spatial direction which is aligned with the object’s long axis.