Spin Dependent Tunneling Magnetic Field Sensors for Clutter-Limited Detection

Highly sensitive, low power, rugged, and compact sensors are required for many military applications. Spin Dependent Tunneling (SDT) devices have been fabricated into magnetic field sensors that perform well, and have the lowest effective noise floor ofany magnetoresistive sensor at high frequencies. Next generation devices, whose noise floor should approach 1 picoTesla / root Hz at 1 Hz, have the potential to meet all of the requirements for the application specified in this solicitation. Additionalwork is required beyond achieving basic sensitivity levels. In particular, algorithms and devices must be developed to permit several of these devices to function as a set of long-baseline gradiometers in a remote setting. This proposed Phase I SBIReffort will address these requirements. A matched field processing approach will be examined as a mode of operating in the field. Several techniques for magnetic field self-calibration and orientation will be studied. These include using the ambientearth's field and geomagnetic noise as calibration sources, and generating calibration fields using the magnetometers themselves. A low power SDT sensor will be made and tested. A successful Phase II project would add electric field measurements, power,and communications hardware to the basic SDT transducers. SDT magnetic field sensors fill a need for a wide range of commercial applications. High impedance, and high sensitivity, wide bandwidth, small size and low power give them significant advantagesin the marketplace. Applications include vehicle detection, currency detection, defect detection using eddy currents, buried object classification, and geophysical analysis.