Analysis and control of heating of magnetic nanoparticles by adding a static magnetic field to an alternating magnetic field

In this paper, we analyzed the influence of a static magnetic field (SMF), generated by a pair of neodymium magnets, on the temperature rise and the specific absorption rate (SAR) of superparamagnetic nanoparticles when exposed to an alternating magnetic field (AMF). Furthermore, we attempted to verify the feasibility of controlling the SAR and steady state temperature increase of the magnetic nanoparticles (MNP) by controlling the magnitude of the applied SMF. Magnetic heating was produced by applying a high-frequency AMF generated by a solenoid coil and an SMF generated by using a pair of magnets; the SMF value could be controlled by varying the separation distance between the magnets. We performed two sets of experiments: in the first, heating was performed using different amplitudes of AMF and SMF. The results showed that while the increase in temperature and SAR was maximum in the absence of an SMF, these values decreased with increasing SMF value, tending to zero as the nanoparticles approached their magnetic saturation state. In the second set of experiments, we used the curve fitting of the experimental data to obtain the required SMF value to achieve two different specific temperatures and SAR values. The measured values of temperature rise and SAR were quite similar to those calculated using the curve-fitted data. Thus, the experimental results confirm the possibility of controlling the heating properties of MNP during magnetic hyperthermia through an applied SMF. Published under license by AIP Publishing.