Resonant magnetic microsensor with &amp;#x03BC;T resolution

Brugger, S.; Oliver, Paul

doi:10.1109/memsys.2008.4443813

Cited by 7 publications

(8 citation statements)

References 12 publications

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“…Once k l and k nl are found, the nonlinear equation 3is solved numerically with MATLAB to find the deviation angle (α) as a function of θ . Finally, the resonant frequency is calculated using (6). 3.0x10 x + 111.4 Figure 3.…”

Section: Device Concept and Theoretical Modelingmentioning

confidence: 99%

Nonlinear sensitivity enhancement of resonant microsensors and its application to low power magnetic sensing

Choi

Yoon²,

Kim

et al. 2011

J. Micromech. Microeng.

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Nonlinearities in resonating structures can be used to increase the sensitivity of sensors based on these structures. An example system, a torsional resonant magnetic sensor, is analyzed to illustrate the effect. The system is composed of a disk-type silicon resonator combined with a permanent magnet supported by multiple micromachined silicon beams, excitation and sensing coils, and a magnetic feedback loop. The effects of nonlinearity on sensitivity have been characterized as a function of beam width and the number of beams using analytical models as well as numerical analysis. By increasing the number of beams while reducing the beam width (and thereby maintaining constant nominal linear resonant frequency), large nonlinearity has been obtained, resulting in an increased change in operating resonant frequency per unit applied magnetic field. The interaction between an external magnetic field surrounding the sensor and the permanent magnet generates a rotating torque on the silicon resonator disk, changing the effective stiffness of the beams and therefore the resonant frequency of the sensor. By monitoring shifts in the resonant frequency while changing the orientation of the sensor with respect to the external magnetic field, the direction of the external magnetic field can be determined. Self-resonance-based electromagnetic excitation of the mechanical resonator enables it to operate with very low power consumption and low excitation voltage. A total system power consumption of less than 140 μW and a resonator actuation voltage of 1.4 mVrms from a ±1.2 V power supply have been demonstrated with a sensitivity of 0.28 Hz/rotational degree to the Earth's magnetic field.

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Section: Device Concept and Theoretical Modelingmentioning

confidence: 99%

Nonlinear sensitivity enhancement of resonant microsensors and its application to low power magnetic sensing

Choi

Yoon²,

Kim

et al. 2011

J. Micromech. Microeng.

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show abstract

“…Starting from the outer dimensions of the concentrator l, w, t, the width of its gap, w g , and its relative magnetic permeability r , all one has to do is to 1. determine its aspect ratiosw = w/l andt = t/l; 2. evaluate D, eff , and eff,max using Eqs. (4), (8) and (9), respectively; 3. determine z = eff / eff,max and decide whether the concentrator is limited by geometry or by permeability; 4. depending on the answer, compute A m or A m,max at the desired relative gap width w g /l, using Eqs. (15) or (16), respectively; 5. depending on the value of z, using Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, a cuboid-shaped planar magnetic concentrator with two narrow gaps and a micromechanical resonator were integrated into a highly sensitive resonant magnetic microsensor with frequency output [8,9].…”

Section: Introductionmentioning

confidence: 99%

Magnetic field amplification by slender cuboid-shaped magnetic concentrators with a single gap

Brugger

Oliver

2010

Sensors and Actuators A: Physical

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“…The interaction of the magnetic material with an external magnetic field alters the resonant frequency. A novel resonant magnetic sensor with frequency output based on the combination of a mechanical resonator and a magnetic field concentrator with two gaps were reported [10,11,12]. The device characterization revealed a high sensitivity of up to 2.56 MHz/T and a resolution of 1.1 μT.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the magnitude and direction of magnetic field by a micromachined cantilever

Chen¹,

Qin²,

Huang³

2011

2011 16th International Solid-State Sensors, Actuators and Microsystems Conference

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This paper presents a new method which can not only measure the magnitude but also the direction of the magnetic field. A structure with a cantilever driven in different modes is used. The magnetic field direction and magnitude are detected by measuring the vibration amplitudes of the different modes for the mechanical cantilever. The vibration mode is activated by an AC current pass through the coil on the cantilever. The displacements of the structure are shown to be a sine and cosine function of the angle of the magnetic field, respectively, and have been verified through experiments. When the vibration amplitudes of different modes of the cantilever are measured, the magnitude and direction of the magnetic field can be gotten.

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Resonant magnetic microsensor with μT resolution

Cited by 7 publications

References 12 publications

Nonlinear sensitivity enhancement of resonant microsensors and its application to low power magnetic sensing

Nonlinear sensitivity enhancement of resonant microsensors and its application to low power magnetic sensing

Magnetic field amplification by slender cuboid-shaped magnetic concentrators with a single gap

Measurement of the magnitude and direction of magnetic field by a micromachined cantilever

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