Giant Magnetoresistive Field Sensors

Magnetic field sensors are currently in widespread use in military, industrial, and automotive applications. They are currently used in automobile distributors and anti-skid braking systems, and are proposed for vehicle location (wheel sensor) in IVHS systems. The utility and performance of these sensors is critically dependent on magnetic field sensitivity. This development applies Giant Magneto-resistance Ratio (GMR) materials (which were initially developed for radiation hard memories) to magentic field sensors for use in vehicles and for vehicle sensing. These materials have magnetoresistances of three to 30 times the magnetoresistances of common materials used today. A sensor suitable for use in IVHS and anti-skid brakes will be used as an initial focus for Phase I. Prototype GMR sensors will be designed, fabricated, and demonstrated in Phase I. Wheatstone bridge designs using GMR materials and will operate from -40 C to +200 C, and give an unamplified signal of 10% of the power supply voltage. Phase II will extend the field range down to 10-3 Oe using low saturation field GMR materials and on-chip signal conditioning electronics. Other applications include position sensing (when used with a permanent magent), current sensing (when used with a current strap), and magentic body sensing (distortion of the Earth's magnetic field). Military, industrial, and automotive applications are numerous. Anticipated Benefits: Greatly improved accuracy and sensitivity of magentic field sensors for collision avoidance and traffic monitoring. Generic low cost position and current sensors for automotive, production, and industrial applications. Military applications include vehicles and mines.