Three-dimensional gradiometer and biomagnetic detection device

Abstract

The application provides a three-dimensional gradiometer and a biomagnetic detection device. The three-dimensional gradiometer comprises a non-magnetic structure, coils, a non-magnetic sleeve, a chip carrier and a chip. Two ends of the non-magnetic sleeve are connected with the non-magnetic structure and the chip carrier respectively. The coils comprise a first coil group, a second coil group and a third coil group. Each coil group is distributed in different dimensions and is symmetrically wound on the non-magnetic structure. Each coil group comprises detection coils and compensation coils which are arranged in an upper and lower spaced manner and are connected in series. The chip carrier is a multi-prism, and the bottom surface of the chip carrier adjacent to the non-magnetic sleeve is a regular polygon structure. A plurality of chips are arranged on different surfaces of the chip carrier in a one-to-one correspondence and are connected with each coil group in a one-to-one correspondence. The three-dimensional gradiometer can measure three dimensions of a magnetic field and remove environmental noise through a clever structural design, and can greatly improve the detection precision of a magnetic signal.

Description

Technical Field

[0001] This invention relates to the field of biomagnetic detection technology, and in particular to a three-dimensional gradient meter and a biomagnetic detection device. Background Technology

[0002] Human tissues such as the heart, brain, muscles, and nerves constantly exhibit cellular electrical activity. Current methods for measuring cellular electrical activity have certain drawbacks. For example, human skin tissue can attenuate the transmission of electrical signals, leading to inaccurate measurements. Furthermore, electrical measurements such as electromyography (EMG) are invasive for patients. Additionally, widely used electrical measurement methods, such as MRI, cannot image the function of various parts of the body, resulting in inaccurate clinical diagnoses for many diseases. In contrast, magnetic signals, which originate from the same source as electrical signals, have spatial propagation capabilities and are not attenuated by subcutaneous tissue, ensuring the authenticity of magnetic signals. Moreover, magnetic measurements are non-invasive, making them more patient-friendly and improving clinical applicability.

[0003] Magnetic sensors can be used to detect magnetic signals passively or spontaneously generated by the human body. Currently, the most sensitive magnetic field detection device is the superconducting quantum interference device (SQUID), which is a sensor based on magnetic flux quantization and the Josephson effect. The Earth's magnetic field strength is 30-50 μT, while SQUID can detect weak magnetic fields on the order of fT, which is one hundred millionth of the Earth's magnetic field strength. To detect extremely weak human body signal magnetic fields from complex environmental fields, other methods are needed to suppress environmental noise and improve the signal-to-noise ratio. The mainstream methods for noise suppression are active shielding and passive shielding. Passive shielding devices mainly include magnetic shielding chambers and magnetic shielding cylinders, which are large and expensive systems. Active shielding devices mainly use gradiometer compensation. The principle is to use a signal channel and a reference channel to form a gradiometer system. The signals collected by the two channels are differentially divided, and the output is the human body signal with a high signal-to-noise ratio.

[0004] Axial gradiometers belong to the hardware gradiometer category within the broader category of gradiometers. They are integrated units where the signal coil and compensation coil are coaxially mounted on the same carrier. Depending on their order, axial gradiometers are classified as first-order, second-order, etc. Currently, gradiometers that only measure gradient differences along one dimension, such as the z-axis, are the most common. Examples include the first-order axial multi-channel gradiometer system for magnetocardiography developed by the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences (refer to patent CN201711080250.0, "A Manufacturing Device and Method for an Axial Gradiometer Based on Superconducting Connections"), and the axial gradiometer design for biomagnetic detection developed by Ningbo University (refer to patent CN218350480U, "A Gradiometer and Weak Magnetic Detection Device"). Because magnetic fields have three-dimensional vector properties, measuring only the magnetic field along the z-axis will inevitably result in the loss of some information in the x and y directions.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a three-dimensional gradiometer and a biomagnetic detection device to solve the problems that the gradiometer in the prior art can only measure a single dimension of the magnetic field, which will result in the loss of some magnetic field information in other directions and lead to inaccurate measurements.

[0007] To achieve the above and other related objectives, the present invention provides a three-dimensional gradient meter, comprising: a non-magnetic structural component, coils, a non-magnetic sleeve, a chip stage, and chips; the two ends of the non-magnetic sleeve are respectively connected to the non-magnetic structural component and the chip stage; the coils include a first coil group, a second coil group, and a third coil group, each coil group being distributed in different dimensions and symmetrically wound in pairs on the non-magnetic structural component; each coil group includes a detection coil and a compensation coil arranged vertically and vertically at intervals and connected in series; the chip stage is a polygonal prism, and the bottom surface of the chip stage adjacent to the non-magnetic sleeve is a regular polygonal structure; multiple chips are correspondingly disposed on different surfaces of the chip stage and connected to each coil group in a corresponding manner.

[0008] Optionally, the three-dimensional gradiometer further includes an electromagnetic shielding cylinder, which is sleeved around the circumference of the chip stage and one end is connected to a non-magnetic sleeve to surround the chip.

[0009] Optionally, there is a gap between the electromagnetic shielding cylinder and the chip.

[0010] Optionally, the materials of the non-magnetic structural components, chip stage, and non-magnetic sleeve include epoxy materials.

[0011] Optionally, the electromagnetic shielding cylinder and the coil are made of niobium, and the chip is a SQUID chip.

[0012] Optionally, both ends of the non-magnetic sleeve are provided with threaded structures to be threadedly connected to the non-magnetic structural component and the electromagnetic shielding cylinder, respectively.

[0013] Optionally, the non-magnetic structural component is a rectangular column, with grooves and multiple through holes located in the grooves on the four sides of the rectangular column. The detection coil and compensation coil of each coil group are both square structures, and each coil group is integrally wound with superconducting wire along the grooves and through holes located in the corresponding dimensions.

[0014] Optionally, the grooves provided along the axial direction of the non-magnetic structural member are located in the middle of each side surface.

[0015] Optionally, the non-magnetic structural component has a through hole at its center, and the non-magnetic sleeve has a through hole arranged along the axial direction. Each coil group and the corresponding chip are connected by a superconducting wire passing through the through hole on the non-magnetic sleeve.

[0016] Optionally, each chip is fixed to a different surface of the chip stage by superconducting screws and superconducting washers.

[0017] Optionally, the coil groups in each dimension are perpendicular to each other and overlap in position.

[0018] The present invention also provides a biomagnetic detection device, which includes a three-dimensional gradient meter as described in any of the above embodiments.

[0019] As described above, the three-dimensional gradiometer and biomagnetic detection device of the present invention have the following beneficial effects: The three-dimensional gradiometer proposed in this invention, through its ingenious structural design, can measure the three dimensions of the magnetic field and remove environmental noise, which can greatly improve the detection accuracy of magnetic signals. The detection device based on this gradiometer design, when applied to three-dimensional imaging in biomagnetic detection, will play an important supplementary role to current detection methods for magnetocardiography, magnetoencephalography, and neuromuscular magnetoencephalography. Attached Figure Description

[0020] Figure 1 The diagram shown is an exemplary assembly structure of the three-dimensional gradient meter provided by the present invention.

[0021] Figure 2 The diagram shown is a structural schematic of the three-dimensional gradient meter provided by the present invention after being assembled with an electromagnetic shielding cylinder.

[0022] Figure 3 The diagram shown is an exemplary structural schematic of a chip stage.

[0023] Figure 4 The diagram shown is an exemplary structural schematic of the non-magnetic structure of the three-dimensional gradient meter provided by the present invention.

[0024] Figure 5 The diagram shown is an exemplary winding schematic of the coil assembly of the three-dimensional gradient meter provided by the present invention.

[0025] Figure 6 The diagram shown is an exemplary structural schematic of the non-magnetic sleeve of the three-dimensional gradient meter provided by the present invention.

[0026] Figure 7 The diagram shows the spatial magnetic field generated by a large signal source.

[0027] Figure 8The diagram shown illustrates the winding principle of the coil of the three-dimensional gradient meter provided by this invention.

[0028] Figure 9 Displayed as Figure 8 The simulation diagram of the coil structure shown is shown.

[0029] Figure 10 and Figure 11 The figure shown is a simulation result of the baseline and radius of the coil of the three-dimensional gradient meter provided by the present invention. Detailed Implementation

[0030] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. For ease of explanation, when detailing the embodiments of the present invention, the cross-sectional views showing the device structure are partially enlarged, not according to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0031] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0032] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0033] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the actual number, shape, and size of the components in the actual implementation. In the actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex. To keep the illustrations as concise as possible, not all structures are shown in the figures.

[0034] Please see Figures 1 to 11 .

[0035] like Figures 1 to 6 As shown, this invention provides a three-dimensional gradient meter, comprising: a non-magnetic structural component 1, a coil 2, a non-magnetic sleeve 3, a chip stage 4, and a chip (not shown); the two ends of the non-magnetic sleeve 3 are respectively connected to the non-magnetic structural component 1 and the chip stage 4; the coil 2 includes a first coil group, a second coil group, and a third coil group, each coil group being distributed in different dimensions, for example, the dimension where the first coil group is located is defined as the X-axis, the dimension where the second coil group is located is defined as the Y-axis, and the dimension where the third coil group is located is defined as the Z-axis, and the three coil groups in each dimension are symmetrically wound in pairs around the non-magnetic structural component. 1. Each coil group includes a detection coil and a compensation coil arranged vertically and in series, with the detection coil and compensation coil arranged parallel to each other. Their size and shape are usually identical to ensure a high signal-to-noise ratio in the output signal. The chip platform 4 is a polygonal prism, and the bottom surface of the chip platform 4 adjacent to the non-magnetic sleeve 3 is a regular polygonal structure. Multiple chips are arranged one-to-one on different surfaces of the chip platform 4 and connected one-to-one with each coil group. Therefore, the chip platform 4 must be at least a triangular prism structure with at least three surfaces for placing chips. In other words, the multiple chips are also symmetrically arranged in pairs, so the distance between the center of any chip and the normal of another chip is equal.

[0036] The structure of the chip platform 4 can be determined according to the number of chips. In a preferred example provided by the present invention, the chip platform 4 is... Figure 3 The rectangular column structure shown has four side surfaces and two end faces. In this embodiment, the end face adjacent to the non-magnetic sleeve 3 is defined as the bottom surface, which is a square structure. In one example, each chip is fixed to a different surface of the chip stage 4 by superconducting screws and superconducting washers. Therefore, the surface of the chip stage 4 used to fix the chips has several screw holes. The chips can be directly fixed to the surface of the chip stage 4, or a PCB board can be fixed to the surface of the chip stage 4, and the chips are fixed to the PCB board. The non-magnetic screws pass through the chips and the PCB board in sequence and are fixed in the screw holes of the chip stage 4. In this embodiment, the chip fixing method is not strictly limited, as long as the chip position corresponds to the position of the coil group and the superconducting connection between the chip and the coil can be ensured.

[0037] The chip stage 4 and the non-magnetic sleeve 3 can be connected using fasteners such as screws or glue. However, in the preferred embodiment provided by this invention, the chip stage 4 and the non-magnetic sleeve 3 are fixed by threads. Therefore, the end of the chip stage 4 connected to the non-magnetic sleeve 3 has a threaded structure. For example, the chip stage 4 has an internally threaded boss extending from its bottom surface for thread matching with the external threaded structure of the non-magnetic sleeve 3. After threaded engagement, the bottom surface of the chip stage 4 can either fit flush with the end face of the non-magnetic sleeve 3 or have a gap. The other end of the chip stage 4, away from the non-magnetic sleeve 3, can also have a threaded boss for connection with the test rod.

[0038] In one example, such as Figure 4As shown, the non-magnetic structural component 1 is a rectangular column. Grooves 11 and multiple through holes 12 located within the grooves 11 are provided on the four sides of the rectangular column. The grooves 11 include longitudinal grooves and transverse grooves. The longitudinal grooves are arranged along the axial direction of the non-magnetic structural component 1 and are located at the center of each side surface. The transverse grooves are located at the upper and lower ends of the rectangular column and are spaced from the edges (especially the upper transverse groove needs to be spaced from the end edge of the rectangular column to avoid overlap between the coil and the threaded structure of the rectangular column, which would affect the connection between the non-magnetic structural component 1 and the non-magnetic sleeve 3). The position and number of through holes 12 are determined by the coil structure. The longitudinal grooves are used for winding the X-axis coil group and the Y-axis coil group, while the transverse grooves are used for winding the Z-axis coil group. This arrangement ensures that the wound X-axis and Y-axis coil groups are located at the center of the side surface, preventing positional deviation for the signal source. Furthermore, in this embodiment, the coil groups in each dimension are perpendicular to each other and overlap in position. Therefore, the transverse and longitudinal grooves intersect perpendicularly, and the two through holes 12 at the ends of each longitudinal groove are simultaneously located within the transverse groove on the same surface. The coil groups in each dimension are perpendicularly symmetrical and overlap in position, so magnetic field interference is canceled out, which helps to prevent magnetic flux crosstalk. In this embodiment, since the non-magnetic structure 1 is rectangular, the detection coil and compensation coil of each coil group wound along the non-magnetic structure 1 are both square structures. Each coil group is integrally wound with superconducting wire along the groove 11 and through hole 12 located in the corresponding dimension. Specifically, in this example, the gradient meter in each dimension is a first-order structure. Therefore, the X-axis coil group 21, Y-axis coil group 22 and Z-axis coil group 23 each include only one detection coil (211 / 221 / 231) and one compensation coil (212 / 222 / 232). Correspondingly, each longitudinal groove is provided with 4 through holes, and each through hole on each surface is correspondingly provided. That is to say, the 4 through holes at the same height on the 4 surfaces are centrally symmetrical, and the 2 through holes at the same height on two opposite surfaces are interconnected. For example, when winding a coil group along the X-axis, the enameled wire used to make the coil is horizontally inserted into the through-hole at the first height and then into the through-hole directly opposite it. The enameled wire is then extended along the groove connected to the through-hole at the second height, and then horizontally inserted into the through-hole at the second height again. This process continues along the groove to the through-hole at the third height (i.e., continuous winding in a U-shape). This process is repeated until the wire is wound back to the initial position along the groove, completing the winding of a single compensation coil and a single detection coil. Then, the same method is used to wind a coil group in the other dimension in the other direction until the final coil group is completed. Figure 5The coil structure is shown. The three-dimensional gradiometer in this embodiment can be considered a combination of three one-dimensional gradiometers, each of which is first-order. In practical use, the order can be changed according to environmental and signal requirements. For example, if the detected magnetic field strength fluctuates significantly, each dimension's gradiometer can be second-order. If a second-order gradiometer is required, the number of through-holes can be increased, and a detection coil and a compensation coil can be wound according to the aforementioned scheme.

[0039] It should be noted that the distribution and depth of the grooves are determined by the structure of each coil group, and the diameter and length of the non-magnetic structural component 1 are designed according to the characteristics of the signal to be detected (the larger the amplitude of the detected signal, the smaller the diameter and length of the non-magnetic structural component 1), and are not limited here.

[0040] This invention creatively employs a rectangular column structure with grooves and through holes to wind the coil. This not only allows for better control of the coil shape and size, ensuring complete consistency in shape and size among each coil group and guaranteeing detection accuracy, but also increases the detection area. Furthermore, winding the coil within the grooves provides excellent protection for the coil.

[0041] Of course, in other examples, the non-magnetic structural component 1 can also be other types of regular polygonal prisms, as long as the placement of the three chips is symmetrical between each other. However, compared to other methods, using a rectangular structure is not only easier to process, but more importantly, it is easier to wind coils of the required shape and size.

[0042] As an example, the non-magnetic structural component 1 also has a central hole 13 arranged axially. Each coil group and the corresponding chip are connected by superconducting wires passing through multiple axially arranged through holes 31 on the non-magnetic sleeve 3. Specifically, after the two ends of the detection coil are led out of the non-magnetic structural component 1 using superconducting wires, the superconducting wires pass sequentially through the through holes 31 of the non-magnetic sleeve 3, the hollow threaded hole of the chip stage 4, and the lead hole, and are connected to two superconducting pads. Each of the two superconducting pads is connected to the chip pad, and the pad is connected to the input coil inside the chip, thereby forming a circuit. The materials of the superconducting wires and superconducting pads include, but are not limited to, niobium.

[0043] The non-magnetic structural component 1 and the non-magnetic sleeve 3, as their names suggest, are non-magnetic and are therefore typically made of non-magnetic materials, such as ceramic materials, epoxy resin materials, or non-magnetic alloy materials. The materials of the non-magnetic structural component 1, the non-magnetic sleeve 3, and the aforementioned chip carrier 4 can be the same or different. In the preferred example provided by this invention, the non-magnetic structural component 1, the non-magnetic sleeve 3, and the chip carrier 4 are all made of epoxy resin material. Epoxy material is used not only because of its non-magnetic properties, but also because it is corrosion-resistant, has high adhesive strength, and, more importantly, is easy to process and mold, making it particularly suitable for processing the structural components in this application.

[0044] The non-magnetic sleeve 3 and the non-magnetic structural component 1 can be connected, for example, using screws or other fasteners, or bonded together with adhesive. However, in the preferred embodiment provided by this invention, such as... Figure 6 As shown, both ends of the non-magnetic sleeve 3 are provided with threaded structures to connect threadedly to the non-magnetic structural component 1 and the electromagnetic shielding cylinder 5, respectively. For example, the end connected to the non-magnetic structural component 1 has an outwardly protruding internally threaded boss to engage with the external thread of the non-magnetic structural component 1. The non-magnetic sleeve 3 has a central hole 32 extending axially in its center. This central hole 32 can be a through hole or a blind hole, and its end has an internally threaded structure to connect threadedly to the threaded boss of the chip carrier 4. The threaded engagement facilitates assembly and disassembly, making it convenient to use.

[0045] In this embodiment, the chip used is preferably a SQUID (Superconducting Quantum Interference Device) chip. Of course, other chips with the same detection principle as the SQUID chip are also applicable, and there is no strict limitation. The SQUID chip has extremely high magnetic field sensitivity, so it generally cannot operate directly in complex Earth environmental fields. Therefore, in a preferred example provided by this invention, the three-dimensional gradient meter also includes an electromagnetic shielding cylinder 5. The electromagnetic shielding cylinder 5 is sleeved around the chip stage 4, and one end is connected to the non-magnetic sleeve 3 to surround the chip. For example, the end of the electromagnetic shielding cylinder 5 is provided with an internal thread to mate with the external thread at the end of the non-magnetic sleeve 3. That is, the chip stage 4 and the electromagnetic shielding cylinder 5 are both threaded to the end of the non-magnetic sleeve 3 facing away from the non-magnetic structural member 1, and the positions where the three are connected overlap. Furthermore, in a further example, to prevent the electromagnetic shielding cylinder 5 from interfering with the chip's measurement of the magnetic field, there is a certain distance between the electromagnetic shielding cylinder 5 and the chip, that is, there is also space for movement between the chip and the electromagnetic shielding cylinder 5. The specific dimensions of this distance are not limited, but are generally within 5mm. The gap between the electromagnetic shielding cylinder 5 and the chip also prevents contact with the chip and potential damage during assembly of the electromagnetic shielding cylinder 5. The material of the electromagnetic shielding cylinder 5 is preferably a superconducting material, preferably but not limited to niobium; for example, it can also be a niobium alloy, such as a niobium-titanium alloy. The metal material inside the coil is preferably niobium, but not limited to this.

[0046] In this invention, the three parts—the non-magnetic structural component 1 for winding the coil, the chip carrier 4, and the non-magnetic sleeve 3 connecting the two—are designed separately and connected to each other by threads, which facilitates installation and disassembly. Furthermore, all three parts can be made of epoxy material, which is convenient for customized processing.

[0047] The three-dimensional gradient meter provided by this invention requires several preparatory steps during assembly, such as fixing multiple chips one-to-one onto different side surfaces of the chip stage 4, and... Figure 5 The coil shown is wound on Figure 4 On the non-magnetic structural component 1 shown, a superconducting metal wire, such as niobium wire, is exposed at the end of the coil (i.e., the insulating material layer at the end of the coil is stripped). The non-magnetic structural component 1 and the non-magnetic sleeve 3 are tightened together. A superconducting wire is used to lead out the end of the coil. After the superconducting wire is led out from the non-magnetic structural component 1, it passes through the through hole 31 of the non-magnetic sleeve 3 until the superconducting wire and the superconducting gasket connecting the chip are fixed with a superconducting screw. Then, the chip stage 4 and the other end of the non-magnetic sleeve 3 opposite to the non-magnetic structural component 1 are tightened together. Finally, the electromagnetic shielding cylinder 5 is fitted around the chip stage 4 and tightened with the non-magnetic sleeve 3, thus completing the assembly of the entire three-dimensional gradiometer. Of course, this assembly process is only exemplary and can be adjusted according to actual conditions.

[0048] The principle of the three-dimensional gradiometer provided by this invention is based on the gradient difference concept. As long as the spatial magnetic field to be detected has temporal and spatial correlation, a system can be formed using a signal channel and a compensation channel, and the difference between the detection results of the two channels can be calculated. However, for different dimensions, signal locations, and characteristics, different compensation schemes are required for the gradient signal. For cases with large signal sources, the resulting spatial magnetic field distribution is as follows... Figure 7 As shown, at the same time Figure 7 The spatial location of the three-dimensional gradiometer is shown. For example... Figure 7 As shown, a three-dimensional gradiometer can be designed according to the traditional gradient concept, where the normals of the three-dimensional coils are perpendicular to each other, with a total of six coils distributed on different surfaces. However, this gradiometer design has specific requirements regarding the location of the signal source, making it difficult to find a suitable location to place the signal source. If the distances of two coils in a certain dimension from the signal source are not significantly different, i.e., the signal source is located in the middle of the two coils, then due to the spatial properties of the magnetic field, the difference between the signal coil and the detection coil will subtract the signal to be detected, thus defeating the purpose of using a three-dimensional gradiometer.

[0049] This invention creatively employs a design that combines a planar gradiometer and an axial gradiometer, with configurations of different coils in different dimensions and in the same dimension, as shown in the example. Figure 8 As shown, the signal coil, i.e., the probe coil, for each axis is located at the bottom, while the reference coil, i.e., the compensation coil, is located at a considerable distance from the signal source. Using the z-axis as a reference, the probe coil and compensation coil form an axial gradiometer, while the gradiometer coils for the x and y axes are planar gradiometers viewed from the x and y dimensions, respectively. In this design, the signal source only needs to be placed at the center of the bottom coil, greatly reducing the requirements for signal positioning. This broadens the application range of the three-dimensional gradiometer of this invention.

[0050] In axial gradient coils, the detection areas of the probe coil and the compensation coil, as well as the distance between them—that is, the baseline of the gradient meter—are key parameters, and the same applies to 3D gradient meter modules. While ensuring a high signal-to-noise ratio for each axis, it is also necessary to control the overall module size. The inventors used Maxwell software to simulate the model, as shown below. Figure 9 As shown, the simulation results of the diameter of the coil in different dimensions relative to the baseline are as follows. Figure 10 and 11 As shown. The baseline of the x / y plane is defined as the sum of the distance between the two coil edges and the coil diameter. In this x / y axis simulation, the horizontal axis represents the distance between the coil edges, and the vertical axis uses the ratio of the magnetic flux detected by the reference channel and the signal channel as the evaluation standard. In practical applications, the magnetic flux detected by the reference channel should be minimized; therefore, a smaller percentage on the vertical axis has greater reference value for actual fabrication. From... Figure 10 and 11 It can be concluded that a flux ratio of less than 1% is used as the evaluation threshold; below this value, the flux measured in the reference channel is considered negligible. Therefore, for the z-axis direction, the baseline should be >40 mm; for the x / y axes, the distance between edges should be >26 mm, but there are different restrictions for different axes. When the radius is 9 mm, an edge-to-edge distance >24 mm can be considered, resulting in a baseline >42 mm. Furthermore, due to the close proximity of the three-dimensional coils, this application employs a symmetrical coil structure to prevent flux crosstalk between coils, i.e., the coils are perpendicular to each other, thus canceling out the crosstalk effect. The specific winding method is described above.

[0051] The three-dimensional gradiometer of this invention comprises a gradient coil consisting of a detection coil and a compensation coil, and a core detection chip. Since the three-dimensional detection signals involved in this invention need to be output separately, each gradiometer detection module requires three chips. Because chip detection is also based on coil-based magnetic field detection, close proximity between chips can cause crosstalk between detection signals. Therefore, this invention uses three faces of a polygonal prism as the chip carrier. The superconducting connection is pre-welded and completed using superconducting screws and washers. Simulation is performed based on the characteristics of the actual detection signal (the simulation process calculates the magnitude of the magnetic field generated by the coil based on Biot-Savart's law; if the actual signal is a magnetocardiogram signal, its amplitude is approximately tens to hundreds of pT). The vertical distance between the chips (here, the vertical distance refers to the distance between the center of one chip and the normal of another chip) is obtained, and parameters are modified within the aforementioned cube to finally determine the overall structure of the chip mounting carrier (a three-dimensional schematic diagram is shown below). Figure 3 (As shown). This polygonal prism must have at least three faces, but is not limited to three faces; for example, it can be a cube. To ensure consistency in the relationships between the chips, each face must have the same base side length, and the chip placement positions must correspond to each other.

[0052] After the gradient coils were determined through the above simulations, it was necessary to design the carrier for winding the coils. Since simultaneously winding circular coils in three dimensions presents certain difficulties and cannot guarantee the balance between the coils, this invention creatively designs all three gradient coils as square. After the gradient coil part was simulated, a suitable side length was selected to replace the diameter of the circle. Simultaneously, a three-dimensional hardware structure with grooves and through holes was fabricated using epoxy material, and niobium wire was placed in... Figure 4 The groove shown is arranged according to Figure 5 The coil is wound in the direction shown, and symmetrical winding of the coil is achieved through the through hole on the side of the epoxy component, thus completing the fabrication of the gradient coil.

[0053] To make the technical solution and advantages of the present invention clearer, the three-dimensional gradient meter of the present invention will be further described below with reference to specific embodiments.

[0054] Example 1

[0055] The overall structure of the three-dimensional gradient meter in this embodiment is referenced. Figure 1 and 2As shown. The niobium wire-wound epoxy rod section (i.e., the non-magnetic structural component) has a z-axis baseline of 70 mm and a side length of 18 mm. The distance between the sides of the plane gradient meters in the x and y directions is 24 mm, and the bottom side length is 18 mm. Multiple 2 mm diameter through holes are located on the side for easy wiring. The grooves for winding the X-axis and Y-axis coils are located in the middle of the side. The groove for winding the z-axis coil is 6 mm from the edge of the module end, with a width of 0.5 mm and a depth of 0.5 mm. A 12 mm diameter through hole is cut at the center of the module's z-axis, and the assembly thread is M12×0.45. The non-magnetic sleeve section also features a threaded protruding cylinder that assembles with the epoxy structural component, and four through holes are provided for easy superconducting wire wiring. Considering subsequent experimental testing, the cylinder has an outer diameter of 30 mm and is equipped with an M30×2 thread for fitting the superconducting shielding cylinder. A 1 cm deep, 12 mm diameter hole is cut into the center of the upper part, with an M12×0.45 thread for easy assembly with the chip stage. Considering the overall space constraints of the experiment and the size of the chip packaging PCB, the chip stage is designed as a cube. The bottom side of the chip stage is 18 mm long and 35 mm long. Two M3 holes and four M2.5 holes are made on three sides for chip mounting. To facilitate the fixing of other parts to the chip stage, a threaded cylinder extends from each end. The cylinder section that contacts the non-magnetic sleeve has a bottom diameter of 12 mm, a length of 15 mm, and an M12×0.45 thread with a length of 5 mm. The upper cylinder of the stage is 30 mm long, 16 mm in diameter, and has an M16×2 thread with a thread length of 5 mm. The superconducting shielding cylinder is made of niobium material with an outer diameter of 33 mm and a wall thickness of 1 mm. It is 50 mm long and has an M30×2 internal thread at the bottom for mounting around the chip to shield against electromagnetic noise from the external environment.

[0056] Of course, the parameters in the above embodiments are merely exemplary and can be adjusted as needed to meet assembly requirements. For example, the diameter of the center hole of the non-magnetic sleeve can be different from the diameter of the center hole of the non-magnetic structural component, and the thread size of each module can be adjusted accordingly. There are no strict limitations on this.

[0057] The working principle of the gradient meter provided by this invention is as follows: when in use, the signal source is placed at the center directly below the three-dimensional gradient meter, so that the distance between the signal source and the three coil groups is equal. The detection coil and compensation coil of each coil group obtain the magnetic field strength, and the corresponding chip performs differential output (differential output is to subtract the obtained results, which can remove the same parts, such as noise in the same environment), thereby obtaining the magnetic field information in each dimension.

[0058] The three-dimensional gradiometer proposed in this invention, through its ingenious structural design, can measure the three dimensions of a magnetic field and remove environmental noise, thus greatly improving the detection accuracy of magnetic signals. A detection device based on this gradiometer, when applied to three-dimensional imaging in biomagnetic detection, will play an important supplementary role to current detection methods for magnetocardiography, magnetoencephalography, and neuromuscular magnetoencephalography.

[0059] This invention also provides a biomagnetic detection device, which includes a three-dimensional gradiometer as described in any of the above embodiments. Therefore, the foregoing description of the three-dimensional gradiometer can be quoted in its entirety here, and will not be repeated for the sake of brevity. The biomagnetic detection device may also include a display module electrically connected to the chip for displaying chip data, or it may also include a liquid nitrogen cooling module, depending on the specific needs. The most significant difference between the biomagnetic detection device of this invention and the prior art is the use of the three-dimensional gradiometer provided by this invention; therefore, other parts will not be elaborated upon in detail.

[0060] By employing the three-dimensional gradient meter provided by this invention, the detection accuracy of the biomagnetic detection device of this invention can be greatly improved.

[0061] Of course, the three-dimensional gradiometer provided by this invention can be used not only for biomagnetic detection, but also for the detection of other fluctuating magnetic fields.

[0062] In summary, this invention provides a three-dimensional gradiometer and a biomagnetic detection device. The three-dimensional gradiometer includes: a non-magnetic structural component, coils, a non-magnetic sleeve, a chip stage, and chips. The two ends of the non-magnetic sleeve are connected to the non-magnetic structural component and the chip stage, respectively. The coils include a first coil group, a second coil group, and a third coil group, each coil group distributed in different dimensions and symmetrically wound in pairs on the non-magnetic structural component. Each coil group includes a detection coil and a compensation coil arranged vertically and intermittently in series. The chip stage is a polygonal prism, and the bottom surface of the chip stage adjacent to the non-magnetic sleeve is a regular polygonal structure. Multiple chips are correspondingly arranged on different surfaces of the chip stage and connected to each coil group. The three-dimensional gradiometer proposed in this invention, through its ingenious structural design, can measure the three dimensions of a magnetic field and remove environmental noise, greatly improving the detection accuracy of magnetic signals. The detection device based on this gradiometer design, when applied to three-dimensional imaging in biomagnetic detection, will play an important supplementary role to current detection methods for magnetocardiography, magnetoencephalography, and neuromuscular magnetoencephalography. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0063] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A three-dimensional gradient meter, characterized in that, include: The system comprises a non-magnetic structural component, coils, a non-magnetic sleeve, a chip stage, and chips. The two ends of the non-magnetic sleeve are connected to the non-magnetic structural component and the chip stage, respectively. The coils include a first coil group, a second coil group, and a third coil group, each distributed in different dimensions and symmetrically wound in pairs around the non-magnetic structural component. Each coil group includes a detection coil and a compensation coil arranged vertically and intermittently in series. The chip stage is a polygonal prism, and the bottom surface of the chip stage adjacent to the non-magnetic sleeve is a regular polygonal structure. Multiple chips are correspondingly arranged on different surfaces of the chip stage and connected to each coil group. The non-magnetic structural component is a rectangular prism with four sides... The structure is provided with grooves and multiple through holes located within the grooves. The grooves include longitudinal grooves and transverse grooves. The longitudinal grooves are arranged along the axial direction of the non-magnetic structure and are located in the middle of each side surface. The transverse grooves are located at the upper and lower ends of the rectangular column and have a certain distance from the edge. The position and number of through holes are determined by the coil structure. The coil groups in each dimension are perpendicular to each other and overlap in position. The transverse grooves and longitudinal grooves intersect each other perpendicularly. The two through holes at the ends of each longitudinal groove are simultaneously located in the transverse grooves on the same surface. The detection coil and compensation coil of each coil group are both square structures. Each coil group is integrally wound with superconducting wire along the grooves and through holes located in the corresponding dimension.

2. The three-dimensional gradient meter according to claim 1, characterized in that, The three-dimensional gradiometer also includes an electromagnetic shielding cylinder, which is sleeved around the chip stage and one end is connected to a non-magnetic sleeve to surround the chip.

3. The three-dimensional gradient meter according to claim 2, characterized in that, There is a gap between the electromagnetic shielding cylinder and the chip.

4. The three-dimensional gradient meter according to claim 2, characterized in that, The non-magnetic structural components, chip carrier, and non-magnetic sleeve are made of epoxy material, the electromagnetic shielding cylinder and coil are made of niobium material, and the chip is a SQUID chip.

5. The three-dimensional gradient meter according to claim 2, characterized in that, Both ends of the non-magnetic sleeve are provided with threaded structures to be threadedly connected to the non-magnetic structural component and the electromagnetic shielding cylinder, respectively.

6. The three-dimensional gradient meter according to claim 1, characterized in that, The non-magnetic structural component has a central hole along the axial direction, and the non-magnetic sleeve has a through hole along the axial direction. Each coil group and the corresponding chip are connected by a superconducting wire passing through the through hole on the non-magnetic sleeve. Each chip is fixed to different surfaces of the chip stage by superconducting screws and superconducting washers.

7. A biomagnetic detection device, characterized in that, The biomagnetic detection device includes a three-dimensional gradient meter as described in any one of claims 1 to 6.

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