AC susceptibility measurement of magnetic nanoparticles using an optically pumped magnetometer and a flux transformer

Magnetic particle imaging (MPI) is used to detect small magnetic fields in magnetic nanoparticles (MNPs). As a first step in MPI systems, we proposed an AC susceptibility measurement system with an optically pumped magnetometer (OPM) based on a flux transformer. First, the magnetic frequency response of the OPM was obtained for calibration. Second, the AC susceptibility of the Resovist MNPs in liquid and solid phases was obtained using the calibration data. These results are consistent with those of previous studies. Therefore, the proposed method is useful for detecting weak MNP magnetic signals in relatively strong magnetic fields and is expected to be applicable to MPI.