Abstract
A microelectromechanical system (MEMS) torsional resonant magnetometer based on Lorentz force was investigated, consisting of torsional structures, torsional beams, metal plates, a coil, and a glass substrate. The Lorentz force, introduced by the interaction between the current in the MEMS coil and an external horizontal magnetic field, leads to displacement of the torsional structure. The strength of the magnetic field is proportional to this displacement, and can be detected with two sensing capacitors fabricated on the torsion structure and the substrate. To improve sensor sensitivity, a folded torsional beam and a double-layer excitation coil were introduced. The fabrication processes included lift-off, anodic bonding, chemical mechanical planarization, silicon nitride (SiNx) deposition, plasma-enhanced chemical vapor deposition, and inductively coupled plasma release. The prototype of the magnetometer was finished and packaged. The sensor performance, including its sensitivity and repeatability, was tested in a low-pressure environment. Additionally, the influences of structural parameters were analyzed, including the resistance of the excitation coil, the initial value of the capacitors, the elastic coefficient of the torsional beam, and the number of layers in the excitation coil. The test results demonstrated that this sensor could meet the requirements for attitude determination systems in low earth orbit satellites.
Highlights
Magnetometers are widely employed in geodesic surveys and aircraft attitude control systems as geomagnetic field detecting sensors [1,2,3]
Compared to microelectromechanical system (MEMS) magnetometers based on the fluxgate effect [12,13], Hall effect [14,15], and magnetoresistance [16,17], microtorsional resonant magnetometers based on the Lorentz force have the advantages of a high quality factor and high reliability [18,19,20,21]
A MEMS torsional resonant magnetometer based on the Lorentz force was studied, and the relevant parameters were optimized
Summary
Magnetometers are widely employed in geodesic surveys and aircraft attitude control systems as geomagnetic field detecting sensors [1,2,3]. Many Lorentz force-based sensors have high requirements for the sensitivity of capacitance measurement, which must be better than 10 aF [24,25,26]. Combining this with new fabrication methods or other sensors, more new devices were developed [27,28]. A MEMS torsional resonant magnetometer based on the Lorentz force was studied, and the relevant parameters were optimized. Ed completely by ICP, reducing the squeeze film air damping effect These results indicate that by reducing the thickness of the structural layer, both the fabrication quality and the ICP success rate were improved.
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