Self-Oscillation-Based Frequency Tracking for the Drive and Detection of Resonance Magnetometers

Abstract

This paper reports a drive and detection method for Micro-Electro-Mechanical System (MEMS)-based Lorentz-force resonance magnetometers. Based on the proposed MEMS magnetometer, a drive and detection method was developed by using self-oscillation to adjust the mismatch between the mechanical resonance frequency and the coil drive frequency as affected by temperature fluctuations and vibration amplitude changes. Not only was the signal-to-noise ratio enhanced by the proposed method compared to the traditional method, but the test system automatically reached resonance frequency very rapidly when powered on. Moreover, the linearity and the measurement range were improved by the magnetic feedback generated by the coil. Test results indicated that the sensitivity of the proposed magnetometer is 59.6 mV/μT and its noise level is 0.25 μT. When operating in ±65 μT, its nonlinearity is 2.5‰—only one-tenth of the former prototype. Its power consumption is only about 250 mW and its size is only 28 mm × 28 mm × 10 mm, or about one-eighth of the original sensor; further, unlike the former device, it can distinguish both positive and negative magnetic fields. The proposed method can also be applied in other MEMS sensors such as gyroscopes and micromirrors to enhance their frequency tracking ability.

A Miniature Resonant and Torsional Magnetometer Based on Lorentz Force

“…As one of the most critical components in the attitude determination systems of spacecraft, they need to be both highly sensitive and accurate. However, the measurement range of the magnetometers can be less than that of sensors used on earth [4,5,6,7]. Additionally, miniaturization is important for the application of magnetometers in small satellites [8,9,10,11].…”

Property Investigation of Replaceable PDMS Membrane as an Actuator in Microfluidic Device

“…Soft lithography is a low-cost and useful method for the fabrication of PDMS devices [2,3] and allows rapid prototyping of microfluidic devices [4,5]. Therefore, various systems such as microelectronics and micro-electromechanical systems (MEMS) [6][7][8][9][10] fabricated by PDMS have been reported. More importantly, PDMS has many properties including elasticity and robustness that are desirable for using in an on-chip actuator system.…”

Detection of cyclic-fold bifurcation in electrostatic MEMS transducers by motion-induced current

“…While these sensors oscillate at resonance, they measure a change in amplitude or frequency of oscillations representing a change in a stimulus. Many electrostatic MEMS sensors [1,[4][5][6][7][8][9][10] adopt this sensing technique. While it is possible to measure resonant motions optically, this is cumbersome and prohibitively expensive.…”