Rectangular Magnetic Pulse Generator for Magnetic Nanoparticle Displacement

Abstract

Magnetic nanoparticles (MNPs) are increasingly used in biomedical applications, including magnetic drug targeting for cancer therapy and magnetomotive ultrasound (MMUS), a technique that uses magnetic fields to displace MNP inclusions within tissue and thereby enable imaging of their distribution. Existing pulsed magnetic field systems have predominantly relied on sinusoidal or Gaussian waveforms, limiting achievable impulse characteristics. In this work, we developed and characterized a capacitor-discharge-based magnetic pulse generator capable of producing rectangular magnetic pulses with durations as short as 1 μs, rise and fall times below 200 ns, and an estimated peak magnetic field of 100mT at a supply voltage of 200 V. The system employs a Silicon Carbide (SiC) MOSFET switch to achieve the required switching speed and power handling, and a low-inductance 4- turn coil to enable rapid field transitions. To assess the feasibility of magnetically-actuated tissue displacement, finite element method simulations were performed in COMSOL Multiphysics. Simulations confirmed that the generated magnetic body forces produce displacements of several micrometers, consistent with MMUS requirements, and that sufficiently long pulse durations induce shear wave propagation through surrounding tissue. These results demonstrate the potential of rectangular magnetic pulses for MNP-based applications.