EPJ Quantum Technol. (2020) 7: 12
https://doi.org/10.1140/epjqt/s40507-020-00087-3

Research

OPM magnetorelaxometry in the presence of a DC bias field

¹ Institute of Electrical and Biomedical Engineering, UMIT—Private University for Health Sciences, Medical Informatics and Technology, Eduard-Wallnöfer-Zentrum 1, 6060, Hall in Tirol, Austria
² Leibniz Institute of Photonic Technology (Leibniz IPHT), Albert-Einstein-Straße 9, 07745, Jena, Germany
³ Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Max-Planck-Ring 14, 98693, Ilmenau, Germany

^* e-mail: aaron.jaufenthaler@umit.at

Received: 28 December 2019
Accepted: 9 September 2020
Published online: 16 September 2020

Abstract

Spatial quantitative information about magnetic nanoparticle (MNP) distributions is a prerequisite for biomedical applications like magnetic hyperthermia and magnetic drug targeting. This information can be gathered by means of magnetorelaxometry (MRX) imaging, where the relaxation of previously aligned MNP’s magnetic moments is measured by sensitive magnetometers and an inverse problem is solved. To remove or minimize the magnetic shielding in which MRX imaging is carried out today, the knowledge of the influence of background magnetic fields on the MNP’s relaxation is a prerequisite. We show MRX measurements using an intensity-modulated optically pumped magnetometer (OPM) in background magnetic fields of up to . We show that the relaxation parameters alter or may be intentionally altered significantly by applying static fields parallel or antiparallel to the MNP’s alignment direction. Further, not only the relaxation process of the MNP’s magnetic moments could be measured with OPM, but also their alignment due to the MRX excitation field.