A micromachined resonant magnetic field sensor

Abstract

A micromachined magnetic field sensor has been designed, fabricated and tested. Its principle of operation is based on the change of resonant frequency of a magnetically sensitive micromechanical resonator as a function of applied external magnetic field. Magnetic sensitivity is achieved by incorporating magnetically soft (permeable) or hard (permanent magnet) materials into the resonator structure. The fabrication of these devices is based on electroplating through sacrificial molds and is completely CMOS-compatible. The functionality of the device has been demonstrated as both an intensity sensor and an angular sensor (i.e., compass). The intensity sensor demonstrated a sensitivity of 20 Oersted in magnetic field intensity, while the angular sensor demonstrated a resolution of approximately 20 degrees. Performance improvements are expected upon integration of these devices with appropriate circuitry.