Scanning Magnetoresistance Microscopy for Imaging Magnetically Labeled DNA Microarrays

We demonstrate the use of a magnetic tunnel junction (MTJ) sensor as a probe for non-contact scanning microscopy of magnetically labeled DNA microarrays. Induced magnetic stray fields from 2.8 mu m diameter magnetic particles are detected using the MTJ sensor, while two dimensional scanning generates the magnetic map of the DNA microarray with a spatial resolution of 1 mu m over a large scan area exceeding 1 cm(2). Current particle-sensor spacing of similar to 20 mu m results in a detection resolution of similar to 30 magnetic particles within each 100 mu m diameter DNA spot. Our results highlight the use of scanning magnetoresistive microscopy as a convenient and powerful technique for the accurate detection and identification of biomolecules tagged with magnetic particles.