Microsensors for Magnetic Fields

The devices and microsystems for measuring magnetic fields have the unique ability to reveal realities that cannot be perceived by the human senses. These transducers, which measure magnetic fields in a range not less than 15 to 16 orders of magnitude and are universal in their applications, are in continuous development.This chapter discusses recent progress in the most frequently used magnetic-field microsensors and MEMS, which are perfectly compatible with microelectronic technologies, most of which are silicon technologies. Up-to-date results are analyzed and abundant information is presented about the following topics: physical mechanisms of the origin of magnetosensitivity,device designs, sensor characteristics and the methods for their determination, biasing and inter-face circuits, the means for performance improvement and overcoming the basic transducer limitations, the most current and prospective applications, anddevelopment trends. Ample references torelevantliterature are included for all modifications of Hall effect devices (orthogonal and parallel field); micromagnetodiodes; magnetoresistors (including feromagnetic versions such as giant magnetoresistance elements); microsensors based on AniBv semiconductors; MOSFET, bipolar, CMOS, unijunction,and split-drain magnetotransistors and related devices; carrier-domain magnetometers; functional multisensorsfor the magnetic field, temperature, and light; 2-D and 3-D vector microsystems for the magnetic field; and magnetogradiometers and digital stochastic magnetotransducers.