Biocompatible, micro- and nano-fabricated magnetic cylinders for potential use as contrast agents for magnetic resonance imaging

• A simple, efficient process for fabricating hollow magnetic cylinders is reported.
• Micron- and nanoscale hollow cylinders composed of iron oxide were fabricated.
• Materials properties of the iron oxide employed in fabrication were analyzed.

This paper reports novel MEMS and NEMS-based fabrication processes for biocompatible, hollow cylindrical ferromagnetic structures for potential use as contrast agents for magnetic resonance imaging (MRI). Compared to previous works on Ni-based cylindrical-nanoshells and Fe-based double-disk particles, biocompatibility and yield issues were strongly considered in this development of a simplified fabrication process incorporating iron oxide thin films. The novel, simplified fabrication processes developed herein yield robust, reproducible fabrication methodologies for the further development of this new class of MRI contrast agents. Specifically, both micron- and nano-scale hollow cylindrical agents were successfully fabricated, the size regimes of which enable a wide array of potential imaging applications. The use of top-down engineering approaches to MRI contrast agent design such as reported herein offers the capacity for multiplexed imaging which may dramatically potentiate the capabilities of MRI imaging.