A novel micromachined magnetic-field sensor

A novel micromachined magnetic-field sensor (MFS) using the Lorentz force is presented. Lateral displacement of surface micromachined structures is generated by the interaction of a defined current through a conducting beam and an external magnetic field. The horizontal displacement of the beam is converted into a capacitance change by comb-electrodes which form a differential capacitor. Electronic circuitry is described that measures the magnetic field by detecting the displacement of the conducting beam. If operated in vacuum at mechanical resonance, a large displacement amplitude is achieved. This magnification of the physical effect by resonant operation has been realized by a new vacuum encapsulation process. Measurements show a substantial magnification of amplitude as characterized by Q-factors above 50. First measurements with prototypes yield magnetic sensitivities of 60000 /sup V///sub A/spl middot/T/ with a detection limit in the dual digit /spl mu/T-range. With improvements in the measurement setup, lower detection limits in the single digit /spl mu/T range (that is one order of magnitude smaller than the earth's magnetic field) are expected. Possible applications are magnetic-field measurement devices and navigation systems.