Date of Award

Spring 1-1-2012

Document Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

John Pellegrino

Second Advisor

Stephen E. Russek

Third Advisor

Scott Bunch


This research evaluates the use of giant magnetoresistance (GMR) sensors to trap and count small concentrations of magnetic nanoparticles (MNPs). Microfabricated GMR sensor arrays have the potential to detect low concentrations of MNPs in macroscale sample volumes (∼10 MNP/mL), at macroscale processing rates (∼1 μL/min). GMR sensors have already been used successfully to detect 16 nm diameter nominal MNPs with a resolution of ∼23 MNPs [1]. Here, we extend previous work by using the strong fringe fields present on the edge of GMR sensors to both trap and detect MNPs. Microfluidic channels allow for continuous flow within the sensors' limited detection range. GMR sensor elements and microfluidic channels can be arrayed to increase the processing rate of the device. Such devices would be less complex and less costly than alternative technologies. They would also make magnetic detection of magnetic labels more feasible for robust immunoassays and filtration studies.