Giant magnetoresistance (GMR) sensor strips are fabricated and modeled with the purpose of detecting a uniform distribution of Fe3O4 magnetic nanoparticles (MNPs) for biological application. We find that the free and fixed layers of GMR sensors play a dominant role in exciting the MNPs, and consequent MNP stray fields lead to increased free layer susceptibility. This result persists even when MNPs are confined to the interior of the sensing region but is enhanced when MNPs are allowed near exterior edges. Our analysis includes three different fabrication configurations on two different spin valve film stacks and agrees well with experimental results.
Bibliographical noteFunding Information:
This work was supported in part by the U.S. Department of Defense W81XWH-11-1-0496 under the Ovarian Cancer Translational Pilot Award. In addition, we acknowledge the support from the Institute for Engineering in Medicine at the University of Minnesota. Parts of this work were carried out in the University of Minnesota I.T. Characterization Facility, which receives partial support from NSF through the NINN program.
We would like to thank Dr. Amy Skubitz, Dr. Kristin Boylan, and Dr. Levi Downs, M.D. for their valuable collaboration on the Ovarian Cancer Translational Pilot Award through the U.S. Department of Defense. Lina Yu and Wei Wang thank the support from Chinese Scholar Council. We would also like to thank the staff at the University of Minnesota Nanofabrication Center and Characterization Facility.
- Giant magnetoresistance
- Magnetic nanoparticles
- Position-dependant sensing