Towards Steering Magnetic Nanoparticles in Drug Targeting Using a Linear
Halbach Array
Abstract
Magnetic nanoparticles offer numerous promising biomedical applications,
e. g. magnetic drug targeting. Here, magnetic drug carriers inside the
human body are directed towards tumorous tissue by an external magnetic
field. However, the success of the treatment strongly depends on the
amount of drug carriers, reaching the desired tumor region. This
steering process is still an open research topic. In this paper, the
previous study of a linear Halbach array is extended by an additional
Halbach array with different magnetization angles between two adjacent
magnets and investigated numerically using COMSOL Multiphysics. The
Halbach arrays are arranged with permanent magnets and generate a
relatively large region of a moderately homogeneous, high magnetic field
while having a strong gradient. This results in a strong magnetic force,
trapping many particles at the magnets. Afterwards, to avoid particle
agglomeration, the Halbach array is flipped to its weak side. Therefore,
the magnetic flux density, its gradient and the resulting magnetic force
are computed for the different Halbach arrays with different
constellations of magnetization directions. Since the calculation of the
gradient can lead to high errors due to the used mesh in Comsol, the
gradient was derived analytically by investigating two different fitting
functions. Overall, the array with a 90° shifted magnetization performs
best, changing the magnetic sides of the array easily and deflecting
more particles. Besides, the results revealed that the magnetic force
dominates directly underneath the magnets compared to the other existing
forces on the SPIONS. Summarized, the results depict that the magnetic
force and, thus, the region where the particles are able to get washed
out, can be adjusted using low-cost permanent magnets.