A new low consumption 3D compass using integrated magnets and piezoresistive nano-gauges

We present for the first time a new concept for low-cost fabrication of a monolithic 3-axis MEMS compass using integrated permanent magnets and based on a technology compatible with inertial MEMS sensors. Piezoresistive gauges of nanometric scale enable to reduce the sensor size without sensitivity loss. Magnetometers were designed for sensitivities of 9V/T and resolutions less than 10nT/√Hz at a bridge current of 100µA and with an active surface of typically 200µm × 300µm. Ultra-low power consumption below 10µW can be achieved. First demonstrators have shown the good reliability of the concept and are in good agreement with design.