A cotton-mouton spectrometer with optimized field cancellation using n-MOSFET-based current switching

Superparamagnetic iron oxide nanoparticles (SPIONs) are used in a variety of medical applications, for example as contrast agents in hyperthermia and magnetic resonance imaging (MRI). Another novel application is the use of SPIONs as tracer in magnetic particle imaging (MPI). Especially for medical applications, the hydrodynamic diameter of the tracers is a crucial factor. The Cotton-Mouton spectrometer (CMS) is a method of measuring the hydrodynamic particle diameter dh using the Cotton-Mouton effect (CME). The CME induces a birefringence in ferrofluids by a magnetic field. The particle diameter is estimated by measuring the time constant of the Brownian relaxation. In this paper, the influence of generation and cancellation of the magnetic nanoparticle saturation using current switching by a metal-oxidesemiconductor field-effect transistor (MOSFET) is studied.