Numerical Simulations of 3D Rotational Drift

Abstract

Due to its broad range of applications in biology and medicine, detection of magnetic particles gains increasing importance. The established method of magnetic particle imaging (MPI) bases on the non-linear magnetization behavior of superparamagnetic nanoparticles [1]. As an alternative approach, rotational drift spectroscopy (RDS) [2,3] aims at detecting the properties of magnetic particles in liquid suspensions based on their motional behavior inside an external rotating magnetic field. Serving as basis for the physical understanding and further development of RDS, the rotational behavior of particles with and without motional restriction is studied by numerical simulation. For this purpose, two different approaches were implemented: one using an explicit Euler algorithm and an improved version using a semi-analytical two-step procedure in order to overcome numerical instabilities of the original code. The results show independently of motional restriction two characteristic types of rotational behavior. The particles either follow the external field with a locked phase lag or exhibit a rotational drift.