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We report on the design, fabrication, and characterization of a microfabricated 3D magnetic field sensor that is suitable for co-integration with inertial sensors to form single-chip inertial measurement units. In contrast to classical resonant MEMS magnetometers, which are based on Lorentz force measurement, our sensor uses permanent magnetic materials and piezoresistive detection with silicon strain gauges of nanometric section, leading to low power consumption and high sensitivity for small sensor size. Thin multilayers of CoFe and PtMn as ferro- and antiferromagnetic materials are integrated within the MEMS fabrication process. Sensitivities of 1.09 V/T for x- and y- components of the magnetic field and 0.124 V/T for z- component of the magnetic field were measured, respectively. To be sensitive to magnetic fields along all three spatial directions, two permanent magnetization directions on the same die are required. Implementation of the two magnetization directions was validated by a measured correlation of 99.7% between x- and y- sensitivity axes. Power consumption of the 3D sensor is for polarization with a 100 μA dc current. With resolutions of 100 nT/√Hz for x- and y-component of the magnetic field and 350 nT/√Hz for z- component, the sensor is suitable for precise measurement of earth magnetic field. [ABSTRACT FROM AUTHOR]

Electrostatically actuated microelectromechanical systems (MEMS) devices integrating a surface micromachined silicon nanowire were batch processed to investigate motion detection with a nanowire piezoresistive gauge. In the proposed implementation, the nanogauge is indirectly coupled to the MEMS structure through an intermediate coupling spring. This design allows an arbitrary choice of MEMS motion detection range and a resolution improvement of in situ nanowire gauge factor measurements. Using this approach, it is demonstrated that an in-plane MEMS displacements up to 180 nm with a noise level down to 0.7 \\rm\AA/\Hz^1/2 can be achieved. MEMS resonance measurement in air and in vacuum by this method is also demonstrated. Results are compared with ex situ measurements of MEMS displacement by optical microscopy and by integrated capacitive detection.\hfill[2012-0206] [ABSTRACT FROM AUTHOR]