Abstract:  Magnetic nanowires can be engineered using composition and shape, and by modulating both of these along their axes (10nm-100um) or their diameters (10-200nm). 

This talk will discuss applications of both single nanowires and arrays of vertically aligned nanowires in biomedical fields, such as nano-barcodes, and biolabels for cells and exosomes, nano-heaters for hyperthermia therapy and organ preservation, and biocomposites. For most of these applications, the reversal mechanism of magnetization can play a critical role.

For example, magnetic coercivity and remanence has been used for contact-free readout of nano-barcode signatures, and the motion of domain walls can limit heating. Magnetic reversal typically occurs by uniform precession and coherent rotation or by domain walls that are transverse or vortices. Here, a novel approach to decoding specific reversal signatures will be described via a fast modification of the first order reversal curve (FORC) technique, called the projection method. In addition to decoding, the method elucidates the mechanisms of reversal which is of interest to the fundamental understanding of nanomagnets and can lead to improved future devices, such as decoding using ferromagnetic resonance (FMR). By understanding the nanomagnetics, these nanowires have been used individually to isolate biospecies, such as cancer cells and tumor-derived exosomes (TEXs) for fundamental studies in medicine.  As nanoscale objects, nanowires have also been suspended in cryopreservation agents to provide the rapid, uniform nanowarming needed to restore preserved tissues and organs. Finally, by aligning nanowires vertically in bio-friendly polymers, applications such as internal band-aids can be coded or functionalized for personalized health care. 

This talk will focus on the measurement methods for each of the biomedical applications mentioned, and will relate these measurements back to the fundamental magnetization engineering of the cylindrical nanowires.

Bio: Bethanie Stadler obtained her PhD from Massachusetts Institute of Technology and BS from Case Western Reserve University.