Microfabricated iron oxide particles for tunable, multispectral magnetic resonance imaging

• A range of iron oxide thin films with varying material properties were deposited using reactive sputtering.
• A tunable range of magnetic properties for iron oxide thin films was achieved.
• Double-disk iron oxide microparticle arrays were fabricated using top-down methods.
• The spectral signatures of the fabricated particle arrays were validated using MRI.

Recently, a novel class of magnetic resonance imaging (MRI) contrast agents developed using top-down microfabrication approaches has been reported. To realize the full capacity of this potentially paradigm-shifting approach to MRI contrast agent design, the integration of biocompatible materials with tunable magnetic properties was sought. To this end, deposition techniques yielding iron oxide thin films with a large range of readily tunable saturation magnetic polarization were developed using reactive sputtering under various conditions. Following the characterization of their chemical compositions and crystalline structures, the iron oxide thin films were subsequently utilized in the fabrication of size and shape specific magnetic double-disk microparticles, yielding the advantages of this new class of MRI contrast agents, including multiplexing capability, diffusion-driven signal amplification, and functional imaging capacity. The integration of iron oxides into this class of fabricated contrast agents offers several distinct advantages, including biocompatibility and the additional degree of freedom in the design of these agents achieved by the tunability of the iron oxide thin film magnetism, both of which are critical features in further optimizing these agents.

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