Modeling the Design of a Magneto-Motive Ultrasound Probe Using a Finite Element Method (2009)

Undergraduate: Sheel Shah

Faculty Advisor: Amy Oldenburg
Department: Physics & Astronomy

---

Due to its excellent spatial resolution, fast performance, cost, and wide availability, ultrasound should be considered the imaging method of choice in most cases. However, ultrasound imaging cannot image molecular content of tissue due to trade-off between spatial resolution and penetration depth. Consequently, super-magnetic iron oxide (SPIO) nanoparticles have been developed as contrast agents to both enhance the contrast and resolution of ultrasound images. When subjected to a time-varying magnetic field, the SPIO nanoparticles oscillate in and out of the focal plane resulting in increased contrast and resolution. We aim to develop a magneto-motive ultrasound machine that takes advantage of these magnetic contrast agents to image tissues. COMSOL Multiphysics, a finite element software package, was used to model and investigate several electromagnet geometries that produced high gradient magnetic fields and simulate the resulting forces on the SPIO nanoparticles. An electromagnet with a ferrite core was designed to maximize the magneto-motive force 2 centimeters below the tip of the electromagnet. The results of the simulations indicate that sufficient force can be generated to magnetically excite SPIO nanoparticles. Thus SPIO nanoparticles can be used as contrast agents in magneto-motive ultrasound imaging, expanding the range of ultrasound imaging to cellular scales and molecular sensitivity.