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 μm 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 μm over a large scan area exceeding 1 cm2. Current particle-sensor spacing of ∼20 μm results in a detection resolution of ∼30 magnetic particles within each 100 μm 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.
Bibliographical noteFunding Information:
This work was supported in part by the National Science Foundation under Grant No. ECCS 0601383. The authors would like to thank J. Pfeiff from the Arraycore Facility at UC Davis for the DNA microarray printing as well as Micromagnetics Inc. for valuable discussions.
- DNA microarray
- Magnetic imaging
- Magnetic tunnel junction (MTJ