Low-Field Magnetic Sensing with GMR Sensors

Industry continues to reap the benefits of solid state magnetic field sensing. Every day new applications are found for solid state magnetic field sensors due to their small size, low power. And relatively low cost. The new frontier for these solid state sensors is very low magnetic fields; the kinds encountered when looking for geophysical anomalies, either natural or man-made, various physiological functions, metal defects, magnetic ink and minute magnetic particles associated with immunoassay. In the past, equipment to perform many of these functions has required a substantial amount of power and has been quite large. In addition, because of their size, the equipment has become costly. Leveraging on substantial government efforts, GMR technology is being applied to these applications today and the newer GMR technologies such as Spin Dependent Tunneling (SDT) will make even more of these applications possible. As with all of solid state technology, many of the now difficult measurements will become more commonplace and provide the ingredients for more precise measurement, diagnosis, and control. Several applications will be presented on the use of individual sensors and arrays being used to address some of these new areas.