Integrated three-axis magnetic sensor and method based on superconducting / magnetoresistance composite structure

Abstract

The present invention discloses an integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure and an application method. The integrated three-axis magnetic sensor of the present invention comprises a superconducting magnetic amplifier and a magnetic track change unit for turning the magnetic field in the horizontal direction along the superconducting magnetic amplifier to the vertical direction. The superconducting magnetic amplifier is provided with four holes arranged in an array, each hole has a narrow area, and the narrow areas of the four holes are rotationally symmetrical relative to the center of the superconducting magnetic amplifier. A magnetoresistive sensitive unit for detecting the magnetic field is provided on one side of the narrow area. The present invention can realize integrated high-precision measurement of three-component magnetic fields, and can effectively improve the orthogonality of the three axes, and has the advantages of high resolution, high orthogonality, small size, and simple implementation.

Description

Technical Field

[0001] The present invention relates to a weak magnetic signal detection technology, and in particular to an integrated three-axis magnetic sensor based on a superconducting / magnetoresistance composite structure and an application method thereof. Background Art

[0002] Nowadays, weak magnetic detection is crucial in geomagnetic navigation, target detection, geological exploration, biomedicine and other fields. The requirements for magnetic field resolution in some fields are up to the fT level, such as brain magnetometry. Among traditional weak magnetic sensors, superconducting quantum interference magnetometers (SQUIDs) that can achieve fT-level magnetic field measurement accuracy have problems such as large size and harsh shielding environment. Magnetoresistive sensors have the advantages of small size, high sensitivity, high stability, and wide linear range, but the detection accuracy of magnetoresistive elements (pT~nT level) is still far behind that of high-sensitivity magnetic sensors (fT level) such as SQUID and optically pumped magnetometers. In 2004, the French Pannetier team proposed a superconducting / magnetoresistive composite sensor, which can achieve fT-level detection accuracy and has the advantages of small size, high stability, and low power consumption.

[0003] Due to its own structural limitations, this sensor can only detect the magnetic field in a single direction perpendicular to the superconducting structure, and cannot measure the magnetic field on the superconducting plane, which has certain limitations for sensor applications. The three-axis magnetic sensor can directly obtain the three-component information of the magnetic field, and has broader application prospects in navigation and attitude positioning.

[0004] There are two ways to achieve three-axis measurement of magnetic field: assembled and integrated. (1) Assembled three-axis magnetic sensors are mainly divided into single-axis plus dual-axis assembly and three single-axis assembly. For example, the three-axis magnetic sensor proposed by my country's Mexin Semiconductor Company (US patent application number is US20110234218A1) uses magnetoresistive single-axis magnetic sensors for the X and Y axes and Hall sensors for the Z axis. The three axes are assembled to achieve three-dimensional magnetic field measurement. The orthogonality of the three axes of the assembled three-axis magnetic sensor depends on the assembly accuracy. Its orthogonality is difficult to guarantee, and it is difficult to meet the requirements of small size and low power consumption. (2) The integrated three-axis magnetic sensor can be manufactured using MEMS technology, which has great advantages in terms of volume, weight, reliability, power consumption, and three-axis orthogonality. There are two main methods for integrated three-axis magnetic sensors. One is to prepare the magnetic sensor on the inclined surface of the substrate to measure the magnetic field components in different directions. For example, the prior art with the US patent application number US20120068698 proposes to engrave a boss or pit on the substrate, prepare the sensitive unit on the inclined side, and then comprehensively process the output signals of each sensitive unit. This implementation method is relatively complicated, and the consistency between the various magnetic sensor elements is difficult to ensure. The second is to use a magnetic line of force steering structure to change the direction of the magnetic line of force and then measure. For example, the prior art with the Chinese patent application number CN201310247033.1 proposes to use a soft magnetic block as a concentrator to gather and turn the magnetic lines of force in the vertical plane to the plane for measurement; the prior art with the US patent application number US20120200292A1 also has a similar effect, and proposes to place a soft magnetic block next to the magnetoresistive sensitive element. However, the structural symmetry, performance consistency and installation position accuracy of the soft magnetic block are difficult to ensure, which will affect the orthogonality of the three-axis sensor. Summary of the invention

[0005] The technical problem to be solved by the present invention is as follows: In view of the problems existing in the prior art such as poor orthogonality of three-axis measurement and insufficient detection accuracy of three-axis magnetic sensors, an integrated three-axis magnetic sensor based on a superconducting / magnetoresistance composite structure and an application method are provided. The present invention can realize integrated high-precision measurement of three-component magnetic fields and can effectively improve the orthogonality of the three axes. It has the advantages of high resolution, high orthogonality, small size and simple implementation.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] An integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure comprises a superconducting magnetic amplifier and a magnetic track change unit for turning the magnetic field in the horizontal direction along the superconducting magnetic amplifier to the vertical direction. The superconducting magnetic amplifier is provided with four holes arranged in an array, each hole has a narrow area, the narrow areas of the four holes are rotationally symmetrical relative to the center of the superconducting magnetic amplifier, and a magnetoresistive sensitive unit for detecting the magnetic field is provided on one side of the narrow area.

[0008] Optionally, the four holes are respectively arranged at the edges of each side of the superconducting magnetic amplifier, and the narrow area is arranged on the outer sides of the holes.

[0009] Optionally, the superconducting magnetic amplifier includes a substrate and a superconducting thin film grown on the substrate and formed by etching, and a metal protective layer is plated on the surface of the superconducting thin film.

[0010] Optionally, the substrate is a LAO or MgO substrate with a thickness of 0.1 to 0.5 mm; the superconducting film is a YBCO film with a thickness of 300 to 2000 nanometers; and the metal protective layer is a gold protective layer with a thickness of 100 to 200 nanometers.

[0011] Optionally, the magnetic track changing unit includes a track changing magnetic ring and four track changing magnetic blocks, the superconducting magnetic amplifier gap is arranged between the track changing magnetic ring and the four track changing magnetic blocks, the track changing magnetic blocks are arranged one-to-one with the holes, and the magnetic fields of two adjacent narrow areas are in opposite directions after being turned by the track changing magnetic ring and the track changing magnetic blocks.

[0012] Optionally, the track-changing magnetic ring is in a square ring shape, and the four track-changing magnetic blocks are respectively aligned with the four corners of the track-changing magnetic ring and arranged oppositely.

[0013] Optionally, the track-changing magnetic ring and the four track-changing magnetic blocks are all made of soft magnetic materials and are fixed on the superconducting magnetic amplifier by bonding with low-temperature glue.

[0014] Optionally, the magnetoresistance sensitive unit is a tunnel junction magnetoresistance sensitive unit, and the distance between the magnetoresistance sensitive unit and the narrow area is within 2 microns.

[0015] In addition, the present invention also provides an application method of the above-mentioned integrated three-axis magnetic sensor based on the superconducting / magnetoresistive composite structure, comprising:

[0016] 1) respectively obtaining magnetic field signals output by four magnetoresistive sensitive units in the detected magnetic field;

[0017] 2) According to the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated, and the function expressions of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated as follows:

[0018]

[0019]

[0020]

[0021] In the above formula, Bx, By and Bz represent the components of the detected magnetic field in the X, Y and Z directions respectively, B1, B2, B3 and B4 represent the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field respectively, G is the amplification factor of each narrow area, μ is the x and y axis track change efficiency of the magnetic track change unit, and λ is the z axis track change efficiency of the magnetic track change unit.

[0022] In addition, the present invention also provides an application system of an integrated three-axis magnetic sensor, including a microprocessor and an integrated three-axis magnetic sensor connected to each other, wherein the integrated three-axis magnetic sensor is the integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure as described above, and the microprocessor is programmed or configured to respectively obtain the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, and calculate the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z according to the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field.

[0023] Compared with the prior art, the present invention mainly has the following advantages: the integrated three-axis magnetic sensor of the present invention includes a superconducting magnetic amplifier and a magnetic track change unit for turning the magnetic field in the horizontal direction of the superconducting magnetic amplifier to the vertical direction, and the superconducting magnetic amplifier is provided with four holes arranged in an array, each hole has a narrow area, and the narrow areas of the four holes are rotationally symmetrical relative to the center of the superconducting magnetic amplifier, and a magnetoresistive sensitive unit for detecting the magnetic field is provided on one side of the narrow area. The present invention can realize integrated high-precision measurement of three-component magnetic fields, and can effectively improve the orthogonality of the three axes, and has the advantages of high resolution, high orthogonality, small size, and simple implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the three-dimensional structure of the integrated three-axis magnetic sensor in an embodiment of the present invention.

[0025] Figure 2 Schematic diagram of the top view of the integrated three-axis magnetic sensor in an embodiment of the present invention.

[0026] Figure 3 Schematic diagram of the bottom view of the integrated three-axis magnetic sensor in an embodiment of the present invention.

[0027] Figure 4 Schematic diagram of the side view structure of the integrated three-axis magnetic sensor in an embodiment of the present invention.

[0028] Figure 5 Schematic diagram of the changing direction of magnetic lines of force in an embodiment of the present invention.

[0029] Legend: 1. Superconducting magnetic amplifier; 11. Hole; 12. Narrow area; 2. Magnetic track change unit; 21. Track change magnetic ring; 22. Track change magnetic block; 3. Magnetoresistance sensitive unit. DETAILED DESCRIPTION

[0030] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the integrated three-axis magnetic sensor based on the superconducting / magnetoresistive composite structure of this embodiment includes a superconducting magnetic amplifier 1 and a magnetic track change unit 2 for turning the magnetic field in the horizontal direction along the superconducting magnetic amplifier 1 to the vertical direction. The superconducting magnetic amplifier 1 is provided with four holes 11 arranged in an array, each hole 11 has a narrow area 12, and the narrow areas 12 of the four holes 11 are rotationally symmetrical relative to the center of the superconducting magnetic amplifier 1. A magnetoresistive sensitive unit 3 (respectively denoted as 3#1 to 3#4) ​​for detecting the magnetic field is provided on one side of the narrow area 12. When there is a horizontal magnetic field input, the magnetic track change unit 2 will turn the magnetic field in the horizontal direction along the superconducting magnetic amplifier 1 to the vertical direction through the hole 11. Since the narrow area 12 of the hole 11 is small in width (generally 2 to 20 microns), the superconducting magnetic amplifier 1 gathers the magnetic field in the narrow area 12, so that it can be detected by the magnetoresistive sensitive unit 3, so that the layout relationship of the narrow areas 12 of the four holes 11 can be used to realize the solution of the components of the detected magnetic field in the three directions of X, Y, and Z.

[0031] like Figure 1 As shown, in this embodiment, four holes 11 are respectively arranged at the edges of each side of the superconducting magnetic amplifier 1, and the narrow area 12 is arranged on the outer side of the hole 11. As an optional implementation example, in this embodiment, the superconducting magnetic amplifier 1 and the hole 11 are both square, and the narrow areas 12 of the four holes 11 are rotationally symmetric relative to the center of the superconducting magnetic amplifier 1, that is, any hole 11 and its narrow area 12 will overlap with the next hole 11 and its narrow area 12 in the rotation direction after rotating 90° relative to the center of the superconducting magnetic amplifier 1.

[0032] In this embodiment, the superconducting magnetic amplifier 1 includes a substrate and a superconducting film grown on the substrate and formed by etching. In order to protect the superconducting magnetic amplifier 1, a metal protective layer is plated on the surface of the superconducting film in this embodiment. Among them, the substrate can be selected from LAO or MgO substrates. In this embodiment, a MgO substrate is specifically used with a thickness of 0.1 to 0.5 mm; the superconducting film can be made of a desired superconducting material according to needs, for example, a YBCO film is selected in this embodiment, with a thickness of 300 to 2000 nanometers; the metal protective layer is relatively thin, and a metal that can achieve protection can be used according to needs. For example, in this embodiment, the metal protective layer is a gold protective layer with a thickness of 100 to 200 nanometers.

[0033] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the magnetic track-changing unit 2 includes a track-changing magnetic ring 21 and four track-changing magnetic blocks 22. The superconducting magnetic amplifier 1 is arranged between the track-changing magnetic ring 21 and the four track-changing magnetic blocks 22 (respectively denoted as 22#1 to 22#4). The track-changing magnetic blocks 22 are arranged one-to-one with the holes 11, and the magnetic fields of two adjacent narrow areas 12 are turned in opposite directions by the track-changing magnetic ring 21 and the track-changing magnetic blocks 22. When there is a horizontal magnetic field input, the track-changing magnetic ring 21 and the four track-changing magnetic blocks 22 turn the magnetic field to a vertical direction, and the turned vertical magnetic field can pass through the holes 11 as much as possible, thereby improving the track-changing efficiency.

[0034] like Figure 2 and Figure 3 As shown, in this embodiment, the track-changing magnetic ring 21 is in a square ring shape, and the four track-changing magnetic blocks 22 are respectively aligned with the four corners of the track-changing magnetic ring 21 and arranged opposite to each other.

[0035] In this embodiment, the track-changing magnetic ring 21 and the four track-changing magnetic blocks 22 are made of soft magnetic materials and fixed on the superconducting magnetic amplifier 1 by low-temperature adhesive bonding. In addition, other magnetic materials can be used as needed, or other installation and fixing methods can be used.

[0036] In this embodiment, the magnetoresistive sensitive unit 3 is a tunnel junction magnetoresistive sensitive unit, and the distance between the magnetoresistive sensitive unit 3 and the narrow area 12 is within 2 micrometers.

[0037] In addition, this embodiment also provides an application method of the aforementioned integrated three-axis magnetic sensor based on the superconducting / magnetoresistive composite structure, including:

[0038] 1) respectively obtaining magnetic field signals output by four magnetoresistive sensitive units 3 in the detected magnetic field;

[0039] 2) According to the magnetic field signals output by the four magnetoresistive sensitive units 3 in the detected magnetic field, the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated, and the function expressions of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated as follows:

[0040]

[0041]

[0042]

[0043] In the above formula, Bx, By and Bz represent the components of the detected magnetic field in the three directions of X, Y and Z respectively, B1, B2, B3 and B4 represent the magnetic field signals output by the four magnetoresistive sensitive units 3 in the detected magnetic field respectively, G is the magnification of each narrow area 12, μ is the x and y axis track change efficiency of the magnetic track change unit 2, and λ is the z axis track change efficiency of the magnetic track change unit 2, thereby realizing high-precision measurement of the integrated three-component magnetic field and effectively improving the orthogonality of the three axes, with the advantages of high resolution, high orthogonality, small size and simple implementation.

[0044] The derivation process of the function expression of the detected magnetic field in the three directions of X, Y and Z is as follows: Assuming that Bx, By and Bz are the detected magnetic field components in the three directions of X, Y and Z, they are Bx′, By′ and Bz′ after the action of the track change structure, and assuming that the track change efficiency of the X and Y axes is μ and the track change efficiency of the Z axis is λ, that is, Bx′=μBx, By′=μBy, Bz′=λBz, and the amplification factor of each narrow area 12 of the superconducting magnetic amplifier 1 is G. Figure 5 As shown, assuming that the magnetoresistive sensitive unit 3 at 12 o'clock is No. 1, and the magnetoresistive sensitive units 3 in the clockwise direction are No. 2, No. 3, and No. 4, then:

[0045] The magnetic field signal B1 output by the magnetoresistance sensitive unit 3 #1 is:

[0046] B1=G(Bz′+Bx′+By′)=G(λBz+μBx+μBy), (4)

[0047] The magnetic field signal B2 output by the magnetoresistance sensitive unit 3 #2 is:

[0048] B2=G(Bz′-Bx′+By′)=G(λBz-μBx+μBy), (5)

[0049] The magnetic field signal B3 output by magnetoresistance sensitive unit #3 is:

[0050] B3=G(Bz′-Bx′-By′)=G(λBz-μBx-μBy), (6)

[0051] The magnetic field signal B4 output by the magnetoresistance sensitive unit 3 #4 is:

[0052] B4=G(Bz′+Bx′-By′)=G(λBz+μBx-μBy), (7)

[0053] From equations (4) to (7), the functional expressions of the components of the detected magnetic field in the three directions of X, Y, and Z shown in equations (1) to (3) can be obtained. When the magnetic field in the X direction is incident, the magnetic lines of force pass vertically through the hole 11 under the action of the magnetic track change unit 2. For the hole 11 corresponding to the #1 magnetoresistive sensitive unit, the magnetic lines of force pass vertically upward, and for the hole 11 corresponding to the #2 magnetoresistive sensitive unit, the magnetic lines of force pass vertically downward. Therefore, the signs corresponding to Bx′ in equations (4) and (5) are opposite, and the reasons for the opposite signs of other signs are similar. Therefore, the layout relationship of the narrow area 12 of the four holes 11 can be used to realize the solution of the components of the detected magnetic field in the three directions of X, Y, and Z.

[0054] In addition, the present embodiment further provides an application system of an integrated three-axis magnetic sensor, comprising a microprocessor and an integrated three-axis magnetic sensor connected to each other, wherein the integrated three-axis magnetic sensor is the aforementioned integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure, and the microprocessor is programmed or configured to respectively obtain magnetic field signals output by four magnetoresistive sensitive units in a detected magnetic field, and calculate the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z according to the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, specifically, calculating the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z according to the function expressions of the components of the detected magnetic field in the three directions of X, Y, and Z shown in equations (1) to (3).

[0055] In addition, the present embodiment also provides an application system of an integrated three-axis magnetic sensor, including a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to respectively obtain magnetic field signals output by four magnetoresistive sensitive units in the detected magnetic field, and calculate the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z according to the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, specifically, the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated according to the function expressions of the components of the detected magnetic field in the three directions of X, Y, and Z shown in equations (1) to (3).

[0056] In addition, this embodiment further provides a computer-readable storage medium, in which a computer program is stored, and the computer program is used to be executed by a microprocessor to respectively obtain the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, and calculate the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z according to the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, specifically, the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z are calculated according to the function expressions of the components of the detected magnetic field in the three directions of X, Y, and Z shown in equations (1) to (3).

[0057] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure, characterized in that: The invention comprises a superconducting magnetic amplifier (1) and a magnetic track change unit (2) for turning a magnetic field in a horizontal direction along the superconducting magnetic amplifier (1) into a vertical direction. The superconducting magnetic amplifier (1) is provided with four holes (11) arranged in an array. Each hole (11) has a narrow area (12). The narrow areas (12) of the four holes (11) are rotationally symmetrical with respect to the center of the superconducting magnetic amplifier (1). A magnetoresistance sensitive unit (3) for detecting a magnetic field is provided on one side of the narrow area (12). The four holes (11) are arranged respectively At the edge of each side of the superconducting magnetic amplifier (1), the narrow area (12) is arranged on the outer side of the hole (11); the magnetic track change unit (2) comprises a track change magnetic ring (21) and four track change magnetic blocks (22); the superconducting magnetic amplifier (1) is arranged in a gap between the track change magnetic ring (21) and the four track change magnetic blocks (22); the track change magnetic blocks (22) are arranged in a one-to-one correspondence with the hole (11); and the magnetic field directions of horizontal magnetic fields in the same direction are opposite after being turned by the track change magnetic ring (21) and the track change magnetic blocks (22) in two adjacent narrow areas (12).

2. The integrated three-axis magnetic sensor based on superconducting / magnetoresistive composite structure according to claim 1, characterized in that: The superconducting magnetic amplifier (1) comprises a substrate and a superconducting film grown on the substrate and formed by etching, and a metal protective layer is plated on the surface of the superconducting film.

3. The integrated three-axis magnetic sensor based on superconducting / magnetoresistive composite structure according to claim 2, characterized in that: The substrate is a LAO or MgO substrate with a thickness of 0.1 to 0.5 mm; the superconducting film is a YBCO film with a thickness of 300 to 2000 nanometers; and the metal protective layer is a gold protective layer with a thickness of 100 to 200 nanometers.

4. The integrated three-axis magnetic sensor based on superconducting / magnetoresistive composite structure according to claim 1, characterized in that: The track-changing magnetic ring (21) is in the shape of a square ring, and the four track-changing magnetic blocks (22) are respectively aligned with the four corners of the track-changing magnetic ring (21) and are arranged opposite to each other.

5. The integrated three-axis magnetic sensor based on superconducting / magnetoresistive composite structure according to claim 4, characterized in that: The track-changing magnetic ring (21) and the four track-changing magnetic blocks (22) are all made of soft magnetic material and are fixed on the superconducting magnetic amplifier (1) by means of low-temperature adhesive bonding.

6. The integrated three-axis magnetic sensor based on superconducting / magnetoresistive composite structure according to claim 1, characterized in that: The magnetoresistance sensitive unit (3) is a tunnel junction magnetoresistance sensitive unit, and the distance between the magnetoresistance sensitive unit (3) and the narrow area (12) is within 2 micrometers.

7. An application method of the integrated three-axis magnetic sensor based on the superconducting / magnetoresistive composite structure according to any one of claims 1 to 6, characterized in that: include: 1) respectively obtaining magnetic field signals output by four magnetoresistive sensitive units (3) in the detected magnetic field; 2) According to the magnetic field signals output by the four magnetoresistive sensitive units (3) in the detected magnetic field, the magnitudes of the components of the detected magnetic field in the three directions of X, Y and Z are calculated, and the function expressions of the components of the detected magnetic field in the three directions of X, Y and Z are calculated as follows: ， ， ， In the above formula, Bx , By and Bz They represent the components of the detected magnetic field in the three directions of X, Y and Z respectively. B1, B2, B3 and B4 represent the magnetic field signals output by the four magnetoresistive sensitive units (3) in the detected magnetic field respectively. G is the magnification of each narrow area (12), is the x- and y-axis track change efficiency of the magnetic track change unit (2), and λ is the z-axis track change efficiency of the magnetic track change unit (2).

8. An application system of an integrated three-axis magnetic sensor, comprising a microprocessor and an integrated three-axis magnetic sensor connected to each other, characterized in that: The integrated three-axis magnetic sensor is an integrated three-axis magnetic sensor based on a superconducting / magnetoresistive composite structure as described in any one of claims 1 to 6, and the microprocessor is programmed or configured to respectively obtain the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field, and calculate the magnitudes of the components of the detected magnetic field in the three directions of X, Y, and Z based on the magnetic field signals output by the four magnetoresistive sensitive units in the detected magnetic field.

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