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A 3-Axis Miniature Magnetic Sensor Based on a Planar Fluxgate Magnetometer with an Orthogonal Fluxguide.

Lu CC, Huang J - Sensors (Basel) (2015)

Bottom Line: Experimental characterization of the miniature fluxgate device demonstrates satisfactory spatial magnetic field detection results in terms of responsivity and noise spectrum.As a result, at an excitation frequency of 50 kHz, a maximum in-plane responsivity of 122.4 V/T appears and a maximum out-of-plane responsivity of 11.6 V/T is obtained as well.The minimum field noise spectra are found to be 0.11 nT/√Hz and 6.29 nT/√Hz, respectively, in X- and Z-axis at 1 Hz under the same excitation frequency.

View Article: PubMed Central - PubMed

Affiliation: Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 106, Taiwan. cclu23@ntut.edu.tw.

ABSTRACT
A new class of tri-axial miniature magnetometer consisting of a planar fluxgate structure with an orthogonal ferromagnetic fluxguide centrally situated over the magnetic cores is presented. The magnetic sensor possesses a cruciform ferromagnetic core placed diagonally upon the square excitation coil under which two pairs of pick-up coils for in-plane field detection are allocated. Effective principles and analysis of the magnetometer for 3-D field vectors are described and verified by numerically electromagnetic simulation for the excitation and magnetization of the ferromagnetic cores. The sensor is operated by applying the second-harmonic detection technique that can verify V-B relationship and device responsivity. Experimental characterization of the miniature fluxgate device demonstrates satisfactory spatial magnetic field detection results in terms of responsivity and noise spectrum. As a result, at an excitation frequency of 50 kHz, a maximum in-plane responsivity of 122.4 V/T appears and a maximum out-of-plane responsivity of 11.6 V/T is obtained as well. The minimum field noise spectra are found to be 0.11 nT/√Hz and 6.29 nT/√Hz, respectively, in X- and Z-axis at 1 Hz under the same excitation frequency. Compared with the previous tri-axis fluxgate devices, this planar magnetic sensor with an orthogonal fluxguide provides beneficial enhancement in both sensory functionality and manufacturing simplicity. More importantly, this novel device concept is considered highly suitable for the extension to a silicon sensor made by the current CMOS-MEMS technologies, thus emphasizing its emerging applications of field detection in portable industrial electronics.

No MeSH data available.


Related in: MedlinePlus

Flux line diagrams illustrate the sensing principle of the planar fluxgate only with a cruciform core and the cross-section is along the longitudinal core: (a) in X-axis sensing direction; (b) in Z-axis sensing direction.
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sensors-15-14727-f002: Flux line diagrams illustrate the sensing principle of the planar fluxgate only with a cruciform core and the cross-section is along the longitudinal core: (a) in X-axis sensing direction; (b) in Z-axis sensing direction.

Mentions: To investigate the sensing principle of our proposed device, we utilize Maxwell® SV 2-D simulator software (Ansoft Corporation., Pittsburgh, PA, USA, 2002) to model and analyze the visualization of magnetism. First, let us verify the sensing principle of the planar fluxgate only with a cruciform core, and the cross-section along the core is shown in Figure 2. For the detection of X-axis (or Y-axis) magnetic fields, the magnetic flux lines are assumed to be parallel to the axial direction of the magnetic core, as depicted in Figure 2a. It can be visibly seen that magnetic flux lines may exhibit convergence or divergence near the ends of the core, and more importantly, a number of flux lines are concentrated or squeezed into the interior of the core until they deviate into air (or vacuum) at the other end. This phenomenon helps generate a variation of the vector field intensity magnitude and flux density around both core ends and this thus can be converted to voltage induced by two pick-up coils beneath them. It is noted that the parallel flux lines near the up and bottom surface of the core may generate the same sensing directions for the corresponding pick-up coils in X-axis due to the fluxguiding (or flux concentration) effect. By implementing a X-Y sensing circuit, one can sum up the induced voltage of two pick-up coils and successfully obtain the vector magnitude of magnetic fields in X-axis (or Y-axis). On the other hand, the Z-axis flux lines, as observed in Figure 2b, are applied to pass through the magnetic core without any flux concentration effect occurred in it. Therefore the planar fluxgate is considered merely sensitive to the in-plane field vectors.


A 3-Axis Miniature Magnetic Sensor Based on a Planar Fluxgate Magnetometer with an Orthogonal Fluxguide.

Lu CC, Huang J - Sensors (Basel) (2015)

Flux line diagrams illustrate the sensing principle of the planar fluxgate only with a cruciform core and the cross-section is along the longitudinal core: (a) in X-axis sensing direction; (b) in Z-axis sensing direction.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507702&req=5

sensors-15-14727-f002: Flux line diagrams illustrate the sensing principle of the planar fluxgate only with a cruciform core and the cross-section is along the longitudinal core: (a) in X-axis sensing direction; (b) in Z-axis sensing direction.
Mentions: To investigate the sensing principle of our proposed device, we utilize Maxwell® SV 2-D simulator software (Ansoft Corporation., Pittsburgh, PA, USA, 2002) to model and analyze the visualization of magnetism. First, let us verify the sensing principle of the planar fluxgate only with a cruciform core, and the cross-section along the core is shown in Figure 2. For the detection of X-axis (or Y-axis) magnetic fields, the magnetic flux lines are assumed to be parallel to the axial direction of the magnetic core, as depicted in Figure 2a. It can be visibly seen that magnetic flux lines may exhibit convergence or divergence near the ends of the core, and more importantly, a number of flux lines are concentrated or squeezed into the interior of the core until they deviate into air (or vacuum) at the other end. This phenomenon helps generate a variation of the vector field intensity magnitude and flux density around both core ends and this thus can be converted to voltage induced by two pick-up coils beneath them. It is noted that the parallel flux lines near the up and bottom surface of the core may generate the same sensing directions for the corresponding pick-up coils in X-axis due to the fluxguiding (or flux concentration) effect. By implementing a X-Y sensing circuit, one can sum up the induced voltage of two pick-up coils and successfully obtain the vector magnitude of magnetic fields in X-axis (or Y-axis). On the other hand, the Z-axis flux lines, as observed in Figure 2b, are applied to pass through the magnetic core without any flux concentration effect occurred in it. Therefore the planar fluxgate is considered merely sensitive to the in-plane field vectors.

Bottom Line: Experimental characterization of the miniature fluxgate device demonstrates satisfactory spatial magnetic field detection results in terms of responsivity and noise spectrum.As a result, at an excitation frequency of 50 kHz, a maximum in-plane responsivity of 122.4 V/T appears and a maximum out-of-plane responsivity of 11.6 V/T is obtained as well.The minimum field noise spectra are found to be 0.11 nT/√Hz and 6.29 nT/√Hz, respectively, in X- and Z-axis at 1 Hz under the same excitation frequency.

View Article: PubMed Central - PubMed

Affiliation: Institute of Mechatronic Engineering, National Taipei University of Technology, Taipei 106, Taiwan. cclu23@ntut.edu.tw.

ABSTRACT
A new class of tri-axial miniature magnetometer consisting of a planar fluxgate structure with an orthogonal ferromagnetic fluxguide centrally situated over the magnetic cores is presented. The magnetic sensor possesses a cruciform ferromagnetic core placed diagonally upon the square excitation coil under which two pairs of pick-up coils for in-plane field detection are allocated. Effective principles and analysis of the magnetometer for 3-D field vectors are described and verified by numerically electromagnetic simulation for the excitation and magnetization of the ferromagnetic cores. The sensor is operated by applying the second-harmonic detection technique that can verify V-B relationship and device responsivity. Experimental characterization of the miniature fluxgate device demonstrates satisfactory spatial magnetic field detection results in terms of responsivity and noise spectrum. As a result, at an excitation frequency of 50 kHz, a maximum in-plane responsivity of 122.4 V/T appears and a maximum out-of-plane responsivity of 11.6 V/T is obtained as well. The minimum field noise spectra are found to be 0.11 nT/√Hz and 6.29 nT/√Hz, respectively, in X- and Z-axis at 1 Hz under the same excitation frequency. Compared with the previous tri-axis fluxgate devices, this planar magnetic sensor with an orthogonal fluxguide provides beneficial enhancement in both sensory functionality and manufacturing simplicity. More importantly, this novel device concept is considered highly suitable for the extension to a silicon sensor made by the current CMOS-MEMS technologies, thus emphasizing its emerging applications of field detection in portable industrial electronics.

No MeSH data available.


Related in: MedlinePlus