Advances in fluxgate sensors
TL;DR: In this paper, the authors present fluxgate sensors with a resolution comparable with high-temperature superconducting quantum interference devices (SQUIDs), while their precision is the best of vectorial field sensors.
Abstract: This paper reviews recent achievements in the technology and design of fluxgate sensors and magnetometers. The major recent trends were decreasing of the sensor size, power consumption and price, and, on the other hand, increasing of the precision in the large range of the measured fields. The potential frequency range was increased up to units of kHz. Present fluxgate sensors have a resolution comparable with high-temperature superconducting quantum interference devices (SQUIDs), while their precision is the best of vectorial field sensors.
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TL;DR: Magnetic sensors can be classified according to whether they measure the total magnetic field or the vector components of the magnetic field as discussed by the authors, and the techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics.
Abstract: Magnetic sensors can be classified according to whether they measure the total magnetic field or the vector components of the magnetic field. The techniques used to produce both types of magnetic sensors encompass many aspects of physics and electronics. Here, we describe and compare most of the common technologies used for magnetic field sensing. These include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive/piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors. The usage of these sensors in relation to working with or around Earth's magnetic field is also presented
1,059 citations
Cites methods from "Advances in fluxgate sensors"
...2) Fluxgate Magnetometer: The fluxgate magnetometer [9] illustrated in Fig....
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TL;DR: A thorough review of state-of-the-art current sensing techniques can be found in this article, where the authors catalog the current sensors according to the underlying physical principle in order to point out their strengths and weaknesses.
Abstract: This paper provides a thorough review of state-of-the-art current sensing techniques. It catalogues the current sensors according to the underlying physical principle in order to point out their strengths and weaknesses.
632 citations
TL;DR: The most important milestone in the field of magnetic sensors was when AMR sensors started to replace Hall sensors in many applications where the greater sensitivity of AMRs was an advantage as mentioned in this paper.
Abstract: The most important milestone in the field of magnetic sensors was when AMR sensors started to replace Hall sensors in many applications where the greater sensitivity of AMRs was an advantage. GMR and SDT sensors finally found applications. We also review the development of miniaturization of fluxgate sensors and refer briefly to SQUIDs, resonant sensors, GMIs, and magnetomechanical sensors.
414 citations
Cites background from "Advances in fluxgate sensors"
...Most fluxgates have a ring core and the same direction of the excitation and measured fields [27]....
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...The data for “low-noise fluxgate” is taken from [27]....
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TL;DR: An alternative approach based on magnetic nanotechnology is presented and their biocompatibility and functionalisation discussed, with spotlights on functionalisation via self assembled monolayers and on methods of reducing nonspecific binding.
Abstract: In this review we discuss conventional methods of performing biological assays and molecular identification and highlight their advantages and limitations. An alternative approach based on magnetic nanotechnology is then presented. Firstly, magnetic carriers are introduced and their biocompatibility and functionalisation discussed, with spotlights on functionalisation via self assembled monolayers and on methods of reducing nonspecific binding. In addition an introduction is provided to the basic physical concepts behind the various types of sensors used to detect magnetic labels. Finally, progress in the field of magnetic biosensors and the outlook for the future are discussed.
207 citations
Cites background from "Advances in fluxgate sensors"
...Some groups have designed magnetic bead biosensors based around the operation of the residence-time-difference (RTD) fluxgate magnetometer [2, 3, 114, 141], which consists of a current-carrying primary coil and a secondary pick-up coil, both wound around a ferromagnetic core....
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184 citations
References
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TL;DR: Fluxgate sensors have been used for measuring d.c. magnetic fields up to 1 mT with a maximum resolution of 10 pT as mentioned in this paper, where the flux is gated by the excitation field, and both crystalline and amorphous ferromagnetic materials can be used for the core.
Abstract: Since the 1930s, fluxgate sensors have been used for measuring d.c. magnetic fields up to 1 mT with a maximum resolution of 10 pT. In the sensor core the flux is gated by the excitation field. The preferable sensor geometry is a ring-core; both crystalline and amorphous ferromagnetic materials can be used for the core. Although a lot of fluxgate magnetometer types have appeared, the classical type with detection of the second harmonics by a phase-sensitive detector is the most popular. Fluxgate sensors are reliable and rugged and their applications range from space research to submarine detection.
338 citations
TL;DR: In this article, the authors used the linear least squares estimator to find independently and uniquely the parameters for a given data set, which has been used successfully in the pre-flight calibration of the state-of-the-art magnetometers on board the magnetic mapping satellites Orsted, Astrid-2, CHAMP and SAC-C.
Abstract: The calibration parameters of a vector magnetometer are estimated only by the use of a scalar reference magnetometer. The method presented in this paper differs from those previously reported in its linearized parametrization. This allows the determination of three offsets or signals in the absence of a magnetic field, three scale factors for normalization of the axes and three non-orthogonality angles which build up an orthogonal system intrinsically in the sensor. The advantage of this method compared with others lies in its linear least squares estimator, which finds independently and uniquely the parameters for a given data set. Therefore, a magnetometer may be characterized inexpensively in the Earth's magnetic-field environment. This procedure has been used successfully in the pre-flight calibration of the state-of-the-art magnetometers on board the magnetic mapping satellites Orsted, Astrid-2, CHAMP and SAC-C. By using this method, full-Earth-field-range magnetometers (± 65536.0 nT) can be characterized down to an absolute precision of 0.5 nT, non-orthogonality of only 2 arcsec and a resolution of 0.2 nT.
216 citations
TL;DR: In this paper, the general characteristics and system level concepts for space-based magnetometers are presented to illustrate the instruments, principles, and tools involved in making accurate magnetic field measurements in space.
Abstract: The general characteristics and system level concepts for space-based magnetometers are presented to illustrate the instruments, principles, and tools involved in making accurate magnetic field measurements in space. Special consideration is given to the most important practical problems that need to be solved to ensure the accuracy of the measurements and their overall impact on system design and mission costs. Several types of instruments used to measure magnetic fields aboard spacecraft and their capabilities and limitations are described according to whether they measure scalar or vector fields. The very large dynamic range associated with magnetic fields of natural origin generally dictates the use of optimized designs for each particular space mission although some wide-range, multimission magnetometers have been developed and used. Earth-field magnetic mapping missions are the most demanding in terms of absolute accuracy and resolution, approaching <1 part in 100 000 in magnitude and a few arcsec i...
203 citations
TL;DR: In this article, a planar 3-dimensional magnetic fluxgate sensor based on micromachined 3D toroidal type planar coils used as excitation and sensing elements is presented, which has excellent linear response over the range of −500 μT to +500 µT with a system sensitivity of 8360 V T−1 and a resolution of 60 nT.
Abstract: This paper presents a new micro-fluxgate magnetic sensor based on micromachined 3-dimensional toroidal type planar coils used as excitation and sensing elements. A rectangular-ring shaped magnetic core and the `second harmonic' operation principle are adopted in this fluxgate sensor. With the use of a newly developed UV-LIGA thick photoresist process and electroplating techniques, excitation and sensing coils as well as permalloy magnetic cores were fabricated to realize a planar three-dimensional magnetic fluxgate sensor on silicon wafers. Excellent linear response over the range of −500 μT to +500 μT, with a system sensitivity of 8360 V T−1 and a resolution of 60 nT was achieved from the sensor realized in this work. The total response range of the sensor is −1.3 to +1.3 mT. The electroplated thick, Cu coil windings result in low coil resistance and a low power consumption of ∼100 mW for an operational frequency range of 1–100 kHz. The small size, the high sensitivity and resolution, and lower power consumption, make this integratable magnetic fluxgate sensor suitable for various applications such as: portable navigation systems, space research, and proximity sensors and detectors.
122 citations