A piezoresistive microcantilever magnetic-field sensor with on-chip self-calibration function integrated

A micromachined piezoresistive cantilever magnetometer, with a self-calibration function on-chip integrated is presented. When the cantilever is subjected to a magnetic field to be measured, the magnetic force will exert upon the magnetized nickel thin-film pattern that is located at the cantilever end. The magnetic force bends the micromechanical cantilever, which is further read out by an integrated piezoresistor. For realizing the self-calibration function, an aluminum spiral is integrated around the cantilever to provide an artificial magnetic field, when an electric current flows through the spiral coil. The artificial magnetic field can be used to drive the cantilever bending and causes a self-calibration output signal. With this on-chip self-calibration scheme, the detection of magnetic field can be immune to the long-term drift in remanence of the magnetized nickel pattern, thereby, improving the sensing stability. Bulk micromachining technologies are used to fabricate the sensors. The formed sensor is used for magnetic-field measurement, resulting in the piezoresistive sensitivity as 1.06 x 10(-4)/mT and the sensing resolution 4.58 mu T. (c) 2006 Elsevier Ltd. All rights reserved.