Magnetic Nanoparticle Fluid Dynamics as Measured by AC Magnetometry

Magnetic particle imaging (MPI) is a developing technology which uses applied AC magnetic fields to render 3D images of the spatial locations of small magnetic tracer particles [1]. MPI is applicable as a medical diagnostic tool, as well as for remote detection and temperature monitoring for space exploration applications. Elucidating the potential interactions of fluid suspensions of MPI tracers when exposed to an external magnetic field is crucial for developing the technology further. The magnetization as a function of the applied AC magnetic field, M(H), is critical to the performance of MPI tracers, and can be altered by the formation of nanoparticle chains. We measure M(H) of tracers via AC magnetometry and its evolution over time to uncover the interparticle dynamics. System calibration can allow for the separation of signals due to macroscopic sample geometry changes from signals due to microscopic effects like nanoparticle chaining. We present characterizations of magnetic particle fluids which allow for an understanding of the AC magnetometer system dynamics, and discuss the application of this data to determining the dynamic behavior of MPI-relevant Perimag fluids.

[1] Gleich B. and Weizenecker J. (2005). Nature. 435:1214.