Magnetic particle imaging with a planar frequency mixing magnetic detection scanner.

We present the first experimental results of our planar-Frequency Mixing Magnetic Detection (p-FMMD) technique to obtain Magnetic Particles Imaging (MPI). The p-FMMD scanner consists of two magnetic measurement heads with intermediate space for the analysis of the sample. The magnetic signal originates from the nonlinear magnetization characteristics of superparamagnetic particles as in case of the usual MPI scanner. However, the detection principle is different. Standard MPI records the higher order harmonic response of particles at a field-free point or line. By contrast, FMMD records a sum-frequency component generated from both a high and a low frequency magnetic field incident on the magnetically nonlinear particles. As compared to conventional MPI scanner, there is no limit on the lateral dimensions of the sample; just the sample height is limited to 2 mm. In addition, the technique does not require a strong magnetic field or gradient because of the mixing of the two different frequencies. In this study, we acquired an 18 mm × 18 mm image of a string sample decorated with 100 nm diameter magnetic particles, using the p-FMMD technique. The results showed that it is feasible to use this novel MPI scanner for biological analysis and medical diagnostic purposes.