, Stephen Dodd, Alan Koretsky
Micro- and nanoscale structuring of electromagnetically susceptible materials underpins many recent advances in biomedical imaging, sensing, and treatment. From plasmonic nanoparticles and surface plasmon enhanced detectors, to microengineered multispectral magnetic resonance imaging (MRI) agents, tailored material geometries enable new functionalities through locally modified fields and amplified signals. This communication introduces a new class of such field-shaping microstructure: the ellipsoidal microcavity. Ellipsoidal particles are already of considerable interest in mathematical packing and granular media studies, and have been shown to self-assemble into anisotropic materials with unique mechanical and optical properties. Here we emphasize that there are additional electromagnetic advantages to their use. In particular, ellipsoids are distinguished by their unique ability to generate truly uniform local electromagnetic fields, an attribute that renders certain hollow ellipsoids ideal candidates for tunable, multispectral MRI agents. This communication discusses these field properties, introduces a new microfabrication protocol that produces almost mathematically exact ellipsoids and ellipsoidal cavities, and demonstrates their use as new multispectral MRI agents.
ellipsoids, microparticle, nanoparticle, MRI, contrast agents