An out-of-plane electromagnetic induction based resonant MEMS magnetometer

Design and fabrication of a microelectromechanical system resonator based on two orthogonal silicon beams with integrated mirror for monitoring in-plane magnetic field

“…After, we determine the out-of-plane displacements of the sensor mirror, as shown in Figure 15. These results are compared respect to those of the analytical model of equation (21). For both models, the mirror displacements have a linear behavior for the applied magnetic field.…”

“…19,300 kg m -3 Thermal expansion coefficient 2.5 3 10 -6 K - 1 14.2 3 10 -6 K -1 FEM: finite element method. 17 Optical 2D sensing 13 mV mT -1 0.634 116 at P atm 3000 3 3000 Herrera-May et al 13 Piezoresistive 1D sensing 230 mV T -1 100.7 419.6 at P atm 472 3 300 Kumar et al 12 Piezoresistive 1D sensing 2.107 mV T -1 400 1.14 3 10 6 at P atm 800 3 800 Mehdizadeh et al 2 Piezoresistive 1D sensing 262 mV nT -1 2300 16,900 at P atm 100 3 100 Kyynäräinen et al 15 Capacitive 3D sensing b b 30,000 at 0.6 Pa 500 3 500 Li et al 14 Capacitive 3D sensing 9.28 pF T -1 49.1 12,700 at P atm 1800 3 1800 Said et al 10 Capacitive 1D sensing -46.6 fF T -1 mA 18.2 b 1969 3 62.5 Park et al 7 Capacitive 1D sensing 0.955 V mT -1 182 13,285 at 5.5 Pa 154 3 60 Li et al 4 Capacitive 1D sensing 6687 ppm mA -1 mT -1 21.9 540 at P atm 1200 3 680 Langfelder et al 3 Capacitive 1D sensing 0.8 aF mA -1 mT -1 28.3 327.9 at P atm 868 3 89 Wu et al 20 Capacitive 1D sensing 272 mV mT -1 1.38 2530.1 at 10 Pa 3000 3 2000 Liu et al 21 Electromagnetic induction 1D sensing 3.5 mV 20, and 30 mA), the sensor reached analytical sensitivities of 15.4, 30.7, and 46.1 mm T -1 , respectively. The sensor registered an experimental resonant frequency of 53 kHz.…”

“…Due to the symmetrical design of the resonator, two Lorentz forces (F L ) in z-axis direction in each side of the second doubly clamped beam are obtained when a magnetic field (B x ) is applied in x-axis direction (see Figure 2(a)). For this case, the dynamic displacements of the mirror are also determined by equation (21). Thus, the proposed sensor can detect orthogonal magnetic fields (B x and B y ) through the measurements of the mirror displacements using an optical system.…”

“…Recently, some research groups have developed magnetic field sensors considering silicon resonators. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] These sensors are smaller than the conventional superconducting quantum interference devices, fluxgate sensors, and optical fiber sensors. Silicon resonators-based sensors can be fabricated using batch standard silicon micromachined fabrication processes, which decrease their cost and allow the integration with electronic circuits.…”

“…Also, these sensors can employ different sensing techniques, including the piezoresistive, capacitive, optical, or piezoelectric. [12][13][14][15][16][17][18][19][20][21] For instance, sensors with piezoresistive transduction have a simple operation principle and easy signal conditioning, but commonly they present offset voltages and their performance may be altered by temperature shifts. Instead, the magnetic field sensors with capacitive detection have less temperature dependence than those with piezoresistive sensing.…”