Introduction

A novel MEMS magnetometer is the object of this brief. The sensor can be fabricated with standard industrial MEMS process and offers high resolution, whilst being of compact in size and with low power consumption. Such device can be integrated with existing inertial sensors (accelerometers, gyroscopes), enabling a fully-MEMS inertial measurement unit, reducing the integration problem of MEMS sensor with magnetic sensor.

Technical features

The new magnetometer is composed of three main elements: a MEMS resonator, a permanent magnet and a pair of magnetic flux concentrators (MFCs). The permanent magnet is patterned on the moving element and placed in proximity of the MFCs. The flux concentrators convey the external magnetic field and produce a magnetic field gradient in the region of the permanent magnets. The force generated by the interaction of the magnetic field gradient and the magnets induces a frequency shift of the MEMS resonator.
Such variation can be detected by the electronics coupled to the sensor and used to compute the incoming magnetic field.

The project leading to this invention has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement No. 828784.

Possible Applications

• Inertial navigation;
• Augmented reality;
• Monitoring of physical activity.

Advantages

• Integration with existing MEMS sensors:
  – Better alignment between sensors;
  – No need of magnetoresistive sensor, with cost and footprint reduction;
• Estimated noise floor of few nT/√Hz or lower;
• Low power consumption, few µW.