A Resonant Lorentz-Force Magnetometer Featuring Slotted Double-Ended Tuning Fork Capable of Operating in a Bias Magnetic Field

• Published in: Journal of microelectromechanical systems Vol. 30; no. 6; pp. 958 - 967
• Main Authors: Wang, Yuan, Song, Xiaoxiao, Li, Fangzheng, Gao, Lu, Li, Chengxin, Xi, Jingqian, Liu, Huafeng, Zhao, Chun, Wang, Chen, Tu, Liang-Cheng, Kraft, Michael
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bias; double-ended tuning fork; Electronic devices; Geological surveys; Jupiter; Lorentz force; Magnetic fields; Magnetic properties; Magnetometer; Magnetometers; Q factors; Q-factor; Resonators; Sensitivity; Sensors; Topology; Tuning
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2021.3113769

Magnetometers are ubiquitous in applications covering many aspects of modern life, such as navigation, smart devices, biomedical systems, geological surveying and aerospace. This work reports a resonant Lorentz-force magnetometer featuring structural topology, in which cavity slots are incorporated in the device structure to improve the thermoelastic dissipation. Such a device is capable of sensing a small Lorentz-force and can be used as a sensitive magnetic field sensor. The most prominent property of this subject is implementing sensing tasks under a large bias magnetic field. The proposed magnetometer achieves a quality factor of 43000 in a vacuum of 4 mPa, a Lorentz-force sensitivity of 0.2 Hz/nN, and a magnetic field change sensitivity of 3375 Hz/T. The topology of the double-ended tuning fork (DETF) using cavity slots in the tine beams resulted in a 5.9-fold enhancement of the Q-factor compared to a common DETF resonator with the same geometry. Experimental characterization of the proposed magnetometer confirms its feasibility and functionality. Experiments about an application scenario with a large pre-existing bias magnetic field were carried out. The prototype device demonstrated a magnetic field change sensitivity of 2585 Hz/T and a noise-limited resolution of 210 nT/<inline-formula> <tex-math notation="LaTeX">\surd </tex-math></inline-formula>Hz, under a bias magnetic field of 0.13 T. [2021-0162]