A simulation study on superparamagnetic nanoparticle based multi-tracer tracking Available to Purchase

Superparamagnetic nanoparticles (MNPs) have been utilized in biomedical sensing, detection, therapeutics, and diagnostics due to their unique magnetic response under different driving fields. In this letter, we report a multi-tracer tracking method that uses different kinds of MNPs as magnetic tracers along with two alternating magnetic fields that can be potentially used to build magnetic-based flow cytometry. By applying two driving fields at frequency $fH$ and $fL$ to MNPs, the response signal is measured at the combinatorial frequencies such as $fH±2fL$ (3rd harmonics), $fH±4fL$ (5th harmonics), $fH±6fL$ (7th harmonics), and so on. Each MNP has its own signature of phase and amplitude, and it is possible to differentiate individual MNPs in a mixture. We theoretically demonstrated colorizing up to 4-MNP tracers in one mixture with an error rate lower than 10%. The performance of multi-tracer imaging can be optimized by increasing the driving field frequency, choosing MNPs with higher saturation magnetization, and using MNP tracers with more centralized size distribution.