The challenges of cancer diagnosis, of pathogen monitoring in clinical samples and in biodefense, and of the growing fields of DNA probe and protein arrays call for sensitive, economical, and highly-parallel detector systems. Rapid advances in genomics and oncogenomics, in particular, are opening a period of great expansion in the range and effectiveness of DNA-and RNA-based diagnostics.

While the current biomolecular recognition technologies can carry out genome-wide profiling of clinical specimens, they require relatively large samples, in the nanogram and microgram levels, which are often not readily available. Sample amplification is an option but can lead to erroneous results. There exists a

Our long-term goal is to develop innovative transducers of biomolecular signals to advance biomolecular recognition technology. Our objective in the proposed work is to build a robust nanomagnetic sensor array capable of sensing sub-50nm magnetic labels and to demonstrate its application to highsensitivity biomolecular screening of ultra-small clinical oncology specimens. Such a nanomagnetic sensor array will capitalize on dramatic advancements in magnetic disk data storage technology, and can be relatively easily integrated into a practical sensor array with extremely high densities of individuallyaddressable sensors (up to -100 per unr', or 10^{8 per mm").} The sensitivity of the device to low-abundance mRNAs or proteins is expected to be at the single-molecule level, facilitating quantitative detection of early disease markers in a clinical setting.