CN105785286B - A kind of fetus heart Magnetic testi probe, system and method - Google Patents
A kind of fetus heart Magnetic testi probe, system and method Download PDFInfo
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- 230000005291 magnetic effect Effects 0.000 title claims abstract description 284
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- 210000003754 fetus Anatomy 0.000 title claims abstract description 12
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/025—Compensating stray fields
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/242—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/43—Detecting, measuring or recording for evaluating the reproductive systems
- A61B5/4306—Detecting, measuring or recording for evaluating the reproductive systems for evaluating the female reproductive systems, e.g. gynaecological evaluations
- A61B5/4343—Pregnancy and labour monitoring, e.g. for labour onset detection
- A61B5/4362—Assessing foetal parameters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0354—SQUIDS
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Abstract
A kind of fetus heart Magnetic testi probe of present invention offer, system and method, including：First three axis magnetometer, the second three axis magnetometer, core gradiometer, the first three axis magnetometer are detected the environmental magnetic field residing for core gradiometer, and magnetic compensation coil is driven to inhibit environmental magnetic field；Second three axis magnetometer is detected the environmental magnetic field after inhibition；Tested magnetic field is detected in environmental magnetic field of the core gradiometer after inhibition, the second three axis magnetometer and core gradiometer output signal are synthesized, the environmental magnetic field signal in core gradiometer output signal is offset, obtains measured signal.The present invention can realize the signal detection of high s/n ratio under unshielded environment, system cost is greatly reduced without using screened room, improve the flexibility of system, breach traditional superconducting quantum interference device magnetic detector applies barrier, superconducting quantum interference device systematic difference is further pushed, there is important economic value.
Description
Technical Field
The invention relates to the field of weak magnetic field detection, in particular to a fetal magnetocardiogram detection probe, a fetal magnetocardiogram detection system and a fetal magnetocardiogram detection method.
Background
A magnetic detector based on a Superconducting Quantum Interference Device (SQUID) is the currently known magnetic detector with the lowest noise level and the most sensitive. The method is widely applied to the field of weak magnetic field detection application such as biological magnetic field, earth magnetic field abnormity, extremely low field nuclear magnetic resonance and the like, and the detection sensitivity of the method reaches Feite (10)-15Tesla) order of magnitude. Has high scientific research and application value in the detection and scientific research of the extremely weak magnetic field.
As shown in fig. 1, the magnetic detector based on the superconducting quantum interference device SQUID mainly consists of the following parts:
1. detection coil, i.e. superconducting pick-up coil: and according to the magnetic field spatial distribution of the detected signal source, winding a coil for coupling the magnetic flux generated by the magnetic field of the detected signal. The pickup coil is wound by a superconducting wire and is connected into the SQUID device and is also an input coil wound by the superconducting wire to form a superconducting loop. According to the magnetic flux quantization effect of the superconducting loop, the magnetic flux coupled by the pickup coil enables the superconducting loop to proportionally generate a current Is, and the current flows into an input coil of the SQUID device to generate magnetic flux which Is coupled into the SQUID magnetic flux sensor.
2. The SQUID magnetic flux sensor is composed of a SQUID device and a matched SQUID reading circuit, and converts magnetic flux sensed by the SQUID into voltage Vout in a linear mode according to proportion.
Thus, the superconducting wound magnetic flux pickup coil is combined with the SQUID magnetic flux sensor, and the linear conversion of the magnetic field-voltage captured by the measured magnetic field is realized. A magnetic detector with magnetic field sensing capability is formed. Because of its very high sensitivity, it is widely used in instruments and equipment with weak magnetic signals.
An important application field of the superconducting quantum interference weak magnetic detector is biological magnetic field detection, construction of high-end medical equipment such as a magnetocardiogram instrument and the like. Wherein the fetal magnetocardiogram instrument has important application potential. The detection means of fetal heart abnormality is very limited, ultrasound can only carry out structural detection, and the electrocardio method is difficult to obtain effective electrocardiosignals due to the problem of maternal conductivity. Only the magnetocardiogram signals are not influenced by the problem of maternal conductivity, can effectively reflect the heart activity information of the fetus, and simultaneously, the fetus heart detection is completely noninvasive, so the fetus heart detection is called as an important means of the fetus heart detection.
The heart of the fetus magnetocardiogram signal detecting instrument is a magnetic sensor of superconducting quantum interference, the fetus magnetocardiogram signal is very weak and only has a plurality of pT (Petesla, 10)-12Tesla), compared to several microtets (microtets: 10-6Tesla) the fluctuation of the earth's environmental magnetic field, it is very difficult to extract signals with high signal-to-noise ratio. Therefore, the special design of the probe is carried out on the basis of the traditional SQUID magnetic detector, and the weak fetal magnetocardiogram signal can be obtained in a strong background interference magnetic field.
The magnetic field detector based on the superconducting quantum interferometer has extremely high sensitivity, and the magnetic field resolution can reach Feite (10)-15Tesla) order of magnitude. Because of its high sensitivity, the measuring range of the sensor is generally small, so that when detecting weak magnetic signals, it encounters great challenge mainly because the environment is full of the earth magnetic field, and the magnitude of the earth magnetic field is largeAt 50 microte (microte: 10)-6Tesla), while the fluctuation of the earth's magnetic field is several hundred nt (nt: 10-9Tesla) to a few microtets. This background magnetic field interference is large relative to the signal that the SQUID magnetic detector can resolve. Therefore, when weak magnetic signal detection is performed, the signal-to-noise ratio of the detection signal will be seriously affected by the background noise.
The technical means adopted to solve the problems are that,
1) a shielded room is used to contain the ambient magnetic field. At present, when the SQUID magnetic detector is used for detecting weak magnetic signals, the weak magnetic signals are required to be detected in a shielding room, namely equipment with an environmental magnetic field shield. The use of the shielding chamber has large occupied space, inconvenient use and very high cost (200-1000 ten thousand yuan), and the application of the SQUID sensor is severely limited.
2) The ambient magnetic field is suppressed using gradient coils. The ambient magnetic field suppression is performed using a first or higher order complex pick-up coil winding method.
Fig. 2 shows a planar gradiometer and fig. 3 shows an axial gradiometer. When the gradient coil is wound, two magnetic field coupling areas are formed, the two areas are equal in size and parallel in normal direction, the magnetic fluxes coupled by the two areas are opposite in sign, namely the coupled magnetic fluxes of the two coils are subtracted, so that magnetic fields with uniform distribution are distributed, and the magnetic fluxes generated by the magnetic fields coupled into the two coil areas are cancelled out, namely common-mode signals are cancelled out. The magnetic field distribution on the two areas is different, namely the magnetic field with gradient is converted into magnetic flux on the gradient coil and is connected into the SQUID magnetic flux sensor for voltage conversion. The gradient coil thus enables the detection of gradient signals, while homogeneous magnetic field signals are suppressed. I.e. the gradient coils have a common-mode rejection capability of the magnetic field.
However, because the winding of the coil is not perfectly symmetrical, the area of the two coils has an error, and the common mode rejection ratio can only be 104On the other hand, it is still insufficient to suppress the strong background magnetic field to a level smaller than the weak magnetic field to be measured. Sensing with conventional gradient coilsThe output of the detector still introduces a large environmental interference magnetic field signal, and the signal-to-noise ratio of signal detection still cannot meet the requirement of fetal magnetocardiogram signal detection in an unshielded environment.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides a fetal magnetocardiogram testing probe, system and method, which are used to solve the problem of the prior art that the ambient magnetic field interferes with the weak magnetic field to be tested.
To achieve the above and other related objects, the present invention provides a fetal magnetocardiogram testing probe, comprising at least:
a first three-axis magnetometer, a second three-axis magnetometer and a core gradiometer;
the first three-axis magnetometer detects an environmental magnetic field where the core gradiometer is located, and is used for driving the magnetic compensation coil to suppress the environmental magnetic field;
the second triaxial magnetometer detects the restrained environmental magnetic field;
the core gradiometer detects the detected magnetic field in the inhibited environmental magnetic field, and the detected signal is obtained by offsetting the environmental magnetic field signal in the output signal of the core gradiometer.
Preferably, the core gradiometer is a superconducting differential mode coil, detecting a magnetic field in a first direction.
More preferably, the second three-axis magnetometer includes magnetic field pickup coils in three directions, and the magnetic fields in the first direction, the second direction, and the third direction are detected respectively, and the first direction, the second direction, and the third direction are perpendicular to each other.
More preferably, the first three-axis magnetometer includes three-direction magnetic field pickup coils that detect the magnetic fields in the first direction, the second direction, and the third direction, respectively.
More preferably, the superconducting wires in the core gradiometer are routed according to a symmetry axis, the areas of the environmental magnetic field balance area and the measured signal sensing area surrounded by two sides of the symmetry axis are equal and symmetrically distributed, the superconducting wires are crossed and routed after passing through the symmetry axis, so that the winding directions of the superconducting wires on two sides of the symmetry axis are opposite, the wire ends of the superconducting wires are led out at the symmetry axis, and the magnetic fluxes coupled with the environmental magnetic field balance area and the measured signal sensing area surrounded by two sides of the symmetry axis are mutually offset.
More preferably, a high-permeability material is arranged in the environmental magnetic field balance area and the measured signal induction area, and the relative permeability of the high-permeability material is not less than 10.
More preferably, the high permeability materials in the ambient magnetic field balance zone and the measured signal induction zone have the same dielectric parameters.
More preferably, the medium parameters include magnetic permeability, filling space.
To achieve the above and other related objects, the present invention also provides a fetal magnetocardiogram testing system, comprising at least: the fetal magnetocardiogram detecting probe, the SQUID sensor, the coil driving circuit, the magnetic compensation coil and the noise cancellation circuit; wherein,
the output end of the first three-axis magnetometer is connected with the SQUID sensors and then connected with the magnetic compensation coils through the coil driving circuits, and the magnetic compensation coils generate magnetic signals to suppress an environmental magnetic field;
the second triaxial magnetometer with another group SQUID sensor back is connected to the output of core gradiometer, is connected to noise cancellation circuit, noise cancellation circuit will the detected magnetic field signal that the core gradiometer detected in the environmental magnetic field after the suppression with the environmental magnetic field after the suppression that the second triaxial magnetometer detected synthesizes, offsets environmental magnetic field signal in the core gradiometer output signal obtains the signal of being surveyed.
To achieve the above and other related objects, the present invention further provides a fetal magnetocardiogram detecting method, comprising at least:
detecting an environment magnetic field of fetal heart magnetism based on a three-axis magnetometer, and driving a magnetic compensation coil to restrain the environment magnetic field; detecting to obtain an inhibited environmental magnetic field based on another three-axis magnetometer; detecting the detected magnetic field in the restrained environmental magnetic field based on a core gradiometer to obtain a detected magnetic field signal with the environmental magnetic field; and synthesizing the detected magnetic field signal with the environmental magnetic field with the suppressed environmental magnetic field signal, and offsetting the environmental magnetic field signal in the output signal of the core gradiometer to obtain the magnetocardiogram signal of the detected fetus.
As mentioned above, the fetal magnetocardiogram testing probe, system and method of the present invention have the following beneficial effects:
the fetal magnetocardiogram detection probe, the fetal magnetocardiogram detection system and the fetal magnetocardiogram detection method can realize weak signal detection with high signal-to-noise ratio in a non-shielding environment, greatly reduce system cost without using a shielding chamber, improve system flexibility, break through the application barrier of the traditional superconducting quantum interferometer magnetic detector, further promote the application of the superconducting quantum interferometer system, and have important economic value.
Meanwhile, the scheme of the invention is suitable for the low-temperature SQUID sensor and the superconducting coil which work in a 4.2K liquid helium temperature region, and is also suitable for the high-temperature superconducting SQUID sensor and the superconducting coil which work in a 77K liquid nitrogen temperature region.
Drawings
Fig. 1 shows a schematic diagram of a prior art magnetic detector based on a superconducting quantum interference device SQUID.
Fig. 2 is a schematic diagram of a prior art planar gradiometer.
Fig. 3 shows a schematic view of a prior art axial gradiometer.
Fig. 4 shows a front view of a fetal magnetocardiogram detection probe of the present invention.
FIG. 5 is a schematic view of the core gradiometer structure of the invention.
Fig. 6 shows a side view of a fetal magnetocardiogram detection probe of the present invention in connection with a SQUID device and sensor circuitry.
Fig. 7 shows a top view of a fetal magnetocardiogram detection probe of the present invention in connection with a SQUID device and sensor circuitry.
Fig. 8 is a schematic diagram of the fetal magnetocardiogram testing system of the present invention.
Fig. 9 is a schematic diagram of an embodiment of the fetal magnetocardiogram detection system of the present invention.
Description of the element reference numerals
1 fetal heart magnetic detection probe
21-23 SQUID sensor
3 drive circuit
4 noise cancellation circuit
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Please refer to fig. 4 to fig. 9. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
As shown in fig. 4 to 7, the present invention provides a fetal magnetocardiogram testing probe 1, where the fetal magnetocardiogram testing probe 1 at least includes:
a first three-axis magnetometer, a second three-axis magnetometer and a core gradiometer;
the first three-axis magnetometer detects an environmental magnetic field where the core gradiometer is located, and is used for driving the magnetic compensation coil to suppress the environmental magnetic field;
the second triaxial magnetometer detects the restrained environmental magnetic field;
the core gradiometer detects the detected magnetic field in the inhibited environmental magnetic field, and the detected signal is obtained by offsetting the environmental magnetic field signal in the output signal of the core gradiometer.
Specifically, the first triaxial magnetometer includes magnetic field pickup coils in three directions, and detects magnetic fields in a first direction, a second direction, and a third direction, respectively. As shown in fig. 4, in the present embodiment, a pickup coil X1 for detecting a magnetic field in the X direction is defined, and the normal direction of the magnetic flux coupling area is parallel to the X axis; a pickup coil Y1 for detecting a magnetic field in the Y direction, the normal direction of the magnetic flux coupling area of which is parallel to the Y axis; and a pickup coil Z1 for detecting a magnetic field in the Z direction, wherein the normal direction of the magnetic flux coupling area is parallel to the Z axis. Wherein, X direction, Y direction and Z direction are vertical to each other to form a three-dimensional space.
Specifically, the second three-axis magnetometer includes magnetic field pickup coils in three directions, and detects magnetic fields in a first direction, a second direction, and a third direction, respectively. As shown in fig. 4, in the present embodiment, a pickup coil X2 for detecting a magnetic field in the X direction is defined, and the normal direction of the magnetic flux coupling area is parallel to the X axis; a pickup coil Y2 for detecting a magnetic field in the Y direction, the normal direction of the magnetic flux coupling area of which is parallel to the Y axis; and a pickup coil Z2 for detecting a magnetic field in the Z direction, wherein the normal direction of the magnetic flux coupling area is parallel to the Z axis.
Specifically, the core gradiometer G1 is a superconducting differential mode coil and detects a magnetic field in a first direction. As shown in fig. 4, in the present embodiment, it is defined that the magnetic field in the X direction is detected. As shown in fig. 5, the superconducting differential mode coil is a planar coil, that is, the superconducting differential mode coil is wired on a plane, and the superconducting wires are wired according to a symmetry axis, in this embodiment, the symmetry axis is a perpendicular line connecting centers of the environmental magnetic field balancing area and the measured signal sensing area, and the environmental magnetic field balancing area and the measured signal sensing area surrounded by two sides of the symmetry axis have equal areas and are symmetrically distributed. In this embodiment, the environmental magnetic field balance area and the detected signal induction area are circular, and other various shapes are applicable to the superconducting differential mode coil of the present invention, which is not limited to this embodiment. The superconducting wires are crossed and routed after passing through the symmetry axis, so that the winding directions of the superconducting wires on two sides of the symmetry axis are opposite, the normal directions of an environmental magnetic field balance area and a detected signal induction area surrounded by two sides of the symmetry axis are parallel to the X axis, namely, the winding directions of the lines are opposite under the condition that the patterns surrounded by coils of the environmental magnetic field balance area and the detected signal induction area are completely symmetrical, and the current is used for explaining that when current flows in the coils, the magnetic fields generated by the coils in the symmetrical areas on two sides of the symmetry axis are distributed symmetrically, the magnetic fields are equal in size and opposite in direction, and the coupling areas formed by the coils are symmetrical in size and are distributed symmetrically. The winding of the lines is opposite, and the lines are analyzed by the electromagnetic induction phenomenon, namely, the magnetic fluxes coupled by coils on two sides of the symmetry axis of the gradiometer are equal under the magnetic field which is uniformly distributed. The induced currents generated by the coupled magnetic fluxes of the two coils cancel each other in the coils. Since the currents cancel each other, the gradient coil does not generate induced currents under a uniform magnetic field. Only under the magnetic field with uneven distribution, namely under the magnetic field with gradient, the magnetic fluxes coupled by the coils at two sides of the symmetry axis are different, so that the generated induced currents are different, and the current generated by subtracting the induced currents of the two coils reflects the signal of the magnetic field gradient.
The line end of the superconducting line is led out at the symmetrical axis, and the magnetic fluxes coupled by the environmental magnetic field balance area and the detected signal induction area are mutually counteracted to form gradient output.
More specifically, high permeability materials are disposed in the environmental magnetic field equilibrium region and the measured signal induction region, and magnetic permeability (magnetic permeability) is a physical quantity that characterizes magnetism of the magnetic medium and represents resistance of magnetic flux generated after current flows through a coil in a space or a magnetic core space, or the ability of the coil to conduct magnetic lines in a magnetic field. The magnetic permeability is expressed as μ ═ B/H, where H is the magnetic field strength, B is the magnetic induction strength, and is usually denoted by the symbol μ, and μ is the magnetic permeability of the medium, or called absolute magnetic permeability. The magnetic permeability referred to in the present invention is defined as relative magnetic permeability μ r, which is defined as the ratio of magnetic permeability μ to vacuum magnetic permeability μ 0, that is, μ r is μ/μ 0. In general: the relative permeability of air or a non-magnetic material is 1, the permeability of a paramagnetic material such as ferromagnetism is >1, the high-permeability material in the present invention means a magnetic conductive material having a relative permeability μ r of not less than 10, and in the present embodiment, a magnetic rod of a high-permeability material is used as a filler. Common high-permeability materials are ferromagnetic materials, such as soft iron, ferrite and the like, wherein the cast iron is 200-400 parts; the silicon steel sheet is 7000-10000; the nickel-zinc ferrite is 10-1000. Since the metal material such as soft iron is conductive and is likely to cause eddy current, it is not preferred, and therefore, in this embodiment, ferrite is preferred as the material with high magnetic permeability, such as nickel zinc ferrite material or manganese zinc ferrite material. The high-permeability materials arranged in the environment magnetic field balance area and the detected signal induction area have the same medium parameters. The medium parameters comprise magnetic permeability and filling space.
In this embodiment, the first triaxial magnetometer and the second triaxial magnetometer are disposed opposite to the core gradiometer G1, and pickup coils X1 and X2 for detecting a magnetic field in the X direction are symmetrically distributed with respect to the longitudinal direction of the core gradiometer G1; pick-up coils Y1 and Y2 for detecting a magnetic field in the Y direction are symmetrically distributed with respect to the longitudinal direction of the core gradiometer G1; pick-up coils Z1 and Z2 that detect a magnetic field in the Z direction are symmetrically distributed with respect to the axis of symmetry of the core gradiometer G1.
Fig. 6 is a side view of the fetal magnetocardiogram testing probe 1 of the present invention after being connected to the SQUID device and the sensor circuit; fig. 7 is a top view of the fetal magnetocardiogram testing probe 1 of the present invention, in which the SQUID device and the sensor circuit are connected.
As shown in fig. 8 to 9, the present invention further provides a fetal magnetocardiogram detecting system, which at least includes:
the fetal magnetocardiogram detecting probe 1, the SQUID sensor, the driving circuit and the noise cancellation circuit; wherein,
after the output end of the first three-axis magnetometer is connected with a group of SQUID sensors, a magnetic signal is generated by the driving circuit 3 to restrain an environmental magnetic field.
Specifically, as shown in fig. 8 to 9, the first three-axis magnetometer includes pickup coils X1, Y1, and Z1, which are respectively connected to the first SQUID sensor 21, and the first SQUID sensor 21 includes a SQUID device and a SQUID readout circuit. The output end of the first SQUID sensor 21 is connected with a driving circuit 3, and the driving circuit 3 comprises a coil driving circuit and a magnetic compensation coil. The first three-axis magnetometer detects an environment magnetic field in the direction of X, Y, Z and generates cancelling magnetic fields B in three directions through a magnetic compensation coilCX、BCYAnd BCZTo the ambient magnetic field BEX、BEYAnd BEZSuppression is performed.
The second triaxial magnetometer with another group SQUID sensor back is connected to the output of core gradiometer, is connected to noise cancellation circuit, noise cancellation circuit will the detected magnetic field signal that the core gradiometer detected in the environmental magnetic field after the suppression with the environmental magnetic field after the suppression that the second triaxial magnetometer detected synthesizes, offsets environmental magnetic field signal in the core gradiometer output signal obtains the signal of being surveyed.
Specifically, as shown in fig. 8 to 9, the second three-axis magnetometer includes pickup coils X2, Y2, and Z2, which are respectively connected to the second SQUID sensor 22, and the second SQUID sensor 22 includes a SQUID device and a SQUID readout circuit. The output end of the second SQUID sensor 22 is connected to a noise cancellation circuit 4, in this embodiment, the noise cancellation circuit 4 is a signal synthesizer. The second three-axis magnetometer detects the suppressed ambient magnetic field in the direction X, Y, Z and outputs the ambient magnetic field to the signal synthesizer. As shown in fig. 8 to 9, the core gradiometer G1 is connected to the third SQUID sensor 23, and the third SQUID sensor 23 includes a SQUID device and a SQUID readout circuit. The output end of the third SQUID sensor 23 is connected to a noise cancellation circuit 4, and in this embodiment, the noise cancellation circuit 4 is a signal synthesizer. The core gradiometer G1 detects the measured magnetic field in the suppressed ambient magnetic field and outputs the detected magnetic field to the signal synthesizer. The signal synthesizer synthesizes the detected magnetic field signal detected by the core gradiometer G1 in the inhibited environmental magnetic field and the inhibited environmental magnetic field detected by the second triaxial magnetometer to offset the environmental magnetic field signal in the output signal of the core gradiometer G1, so that a clean detected signal is obtained, and the signal-to-noise ratio is greatly improved.
The invention also provides a fetal magnetocardiogram detection method, which is based on the three-axis magnetometer to detect the fetal magnetocardiogram environmental magnetic field and drive the magnetic compensation coil to inhibit the environmental magnetic field; detecting to obtain an inhibited environmental magnetic field based on another three-axis magnetometer; detecting the detected magnetic field in the restrained environmental magnetic field based on a core gradiometer to obtain a detected magnetic field signal with the environmental magnetic field; and synthesizing the detected magnetic field signal with the environmental magnetic field with the suppressed environmental magnetic field signal, and offsetting the environmental magnetic field signal in the output signal of the core gradiometer to obtain the magnetocardiogram signal of the detected fetus.
As mentioned above, the fetal magnetocardiogram testing probe, system and method of the present invention have the following beneficial effects:
the fetal magnetocardiogram detection probe, the fetal magnetocardiogram detection system and the fetal magnetocardiogram detection method can realize weak signal detection with high signal-to-noise ratio in a non-shielding environment, greatly reduce system cost without using a shielding chamber, improve system flexibility, break through the application barrier of the traditional superconducting quantum interferometer magnetic detector, further promote the application of the superconducting quantum interferometer system, and have important economic value.
Meanwhile, the scheme of the invention is suitable for the low-temperature SQUID sensor and the superconducting coil which work in a 4.2K liquid helium temperature region, and is also suitable for the high-temperature superconducting SQUID sensor and the superconducting coil which work in a 77K liquid nitrogen temperature region.
In summary, the present invention provides a fetal magnetocardiogram testing probe, including: a first three-axis magnetometer, a second three-axis magnetometer and a core gradiometer; the first three-axis magnetometer detects an environmental magnetic field where the core gradiometer is located, and is used for driving the magnetic compensation coil to suppress the environmental magnetic field; the second triaxial magnetometer detects the restrained environmental magnetic field; the core gradiometer detects the detected magnetic field in the inhibited environmental magnetic field, and the detected signal is obtained by offsetting the environmental magnetic field signal in the output signal of the core gradiometer. The fetal magnetocardiogram detecting system comprises a fetal magnetocardiogram detecting probe, a SQUID sensor, a coil driving circuit, a magnetic compensation coil and a noise cancellation circuit; the output end of the first three-axis magnetometer is connected with the SQUID sensors and then connected with the magnetic compensation coils through the coil driving circuits, and the magnetic compensation coils generate magnetic signals to suppress an environmental magnetic field; the second triaxial magnetometer with another group SQUID sensor back is connected to the output of core gradiometer, is connected to noise cancellation circuit, noise cancellation circuit will the detected magnetic field signal that the core gradiometer detected in the environmental magnetic field after the suppression with the environmental magnetic field after the suppression that the second triaxial magnetometer detected synthesizes, offsets environmental magnetic field signal in the core gradiometer output signal obtains the signal of being surveyed. The fetal magnetocardiogram detection method comprises the steps of detecting an environmental magnetic field of fetal magnetocardiogram based on a three-axis magnetometer, and driving a magnetic compensation coil to inhibit the environmental magnetic field; detecting to obtain an inhibited environmental magnetic field based on another three-axis magnetometer; detecting the detected magnetic field in the restrained environmental magnetic field based on a core gradiometer to obtain a detected magnetic field signal with the environmental magnetic field; and synthesizing the detected magnetic field signal with the environmental magnetic field with the suppressed environmental magnetic field signal, and offsetting the environmental magnetic field signal in the output signal of the core gradiometer to obtain the magnetocardiogram signal of the detected fetus. The fetal magnetocardiogram detection probe, the fetal magnetocardiogram detection system and the fetal magnetocardiogram detection method can realize weak signal detection with high signal-to-noise ratio in a non-shielding environment, greatly reduce system cost without using a shielding chamber, improve system flexibility, break through the application barrier of the traditional superconducting quantum interferometer magnetic detector, further promote the application of the superconducting quantum interferometer system, and have important economic value. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A fetal magnetocardiogram testing probe, comprising at least:
a first three-axis magnetometer, a second three-axis magnetometer and a core gradiometer;
the first three-axis magnetometer detects an environmental magnetic field where the core gradiometer is located, and then the output signal of the first three-axis magnetometer drives the magnetic compensation coil to suppress the environmental magnetic field;
the second triaxial magnetometer detects the restrained environmental magnetic field;
the core gradiometer detects the detected magnetic field in the inhibited environmental magnetic field, and the environmental magnetic field signal in the output signal of the core gradiometer is offset to obtain the detected signal.
2. The fetal magnetocardiogram testing probe of claim 1, wherein: the core gradiometer is a superconducting differential mode coil that detects a magnetic field in a first direction.
3. The fetal magnetocardiogram testing probe of claim 2, wherein: the second triaxial magnetometer comprises magnetic field pickup coils in three directions, and the magnetic fields in the first direction, the second direction and the third direction are detected respectively, wherein the first direction, the second direction and the third direction are pairwise perpendicular.
4. The fetal magnetocardiogram testing probe of claim 3, wherein: the first three-axis magnetometer comprises magnetic field pickup coils in three directions, and the magnetic fields in the first direction, the second direction and the third direction are detected respectively.
5. The fetal magnetocardiogram testing probe of claim 2, wherein: the superconducting wires in the core gradiometer are arranged according to a symmetrical axis, the areas of the environmental magnetic field balance area and the measured signal sensing area which are surrounded by two sides of the symmetrical axis are equal and are symmetrically distributed, the superconducting wires are crossed and arranged after passing through the symmetrical axis, so that the winding directions of the superconducting wires on the two sides of the symmetrical axis are opposite, the wire ends of the superconducting wires are led out at the symmetrical axis, and the magnetic fluxes coupled with the environmental magnetic field balance area and the measured signal sensing area which are surrounded by the two sides of the symmetrical axis are mutually offset.
6. The fetal magnetocardiogram testing probe of claim 5, wherein: and high-permeability materials are arranged in the environment magnetic field balance area and the measured signal induction area, and the relative permeability of the high-permeability materials is not less than 10.
7. The fetal magnetocardiogram testing probe of claim 5, wherein: the high-permeability materials in the environmental magnetic field balance area and the measured signal induction area have the same medium parameters.
8. The fetal magnetocardiogram testing probe of claim 7, wherein: the medium parameters comprise magnetic permeability and filling space.
9. A fetal magnetocardiogram testing system, comprising at least:
the fetal magnetocardiogram testing probe, SQUID sensor, coil drive circuitry, magnetic compensation coil, and noise cancellation circuitry of any of claims 1 to 8; wherein,
the output end of the first three-axis magnetometer is connected with the SQUID sensors and then connected with the magnetic compensation coils through the coil driving circuits, and the magnetic compensation coils generate magnetic signals to suppress an environmental magnetic field;
the second triaxial magnetometer with another group SQUID sensor back is connected to the output of core gradiometer, is connected to noise cancellation circuit, noise cancellation circuit will the detected magnetic field signal that the core gradiometer detected in the environmental magnetic field after the suppression with the environmental magnetic field after the suppression that the second triaxial magnetometer detected synthesizes, offsets environmental magnetic field signal in the core gradiometer output signal obtains the signal of being surveyed.
10. A fetal magnetocardiogram detection method, comprising at least:
detecting an environment magnetic field of fetal heart magnetism based on a three-axis magnetometer, and driving a magnetic compensation coil to restrain the environment magnetic field; detecting to obtain an inhibited environmental magnetic field based on another three-axis magnetometer; detecting the detected magnetic field in the restrained environmental magnetic field based on a core gradiometer to obtain a detected magnetic field signal with the environmental magnetic field; and synthesizing the detected magnetic field signal with the environmental magnetic field with the suppressed environmental magnetic field signal, and offsetting the environmental magnetic field signal in the output signal of the core gradiometer to obtain the magnetocardiogram signal of the detected fetus.
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| CN112842344B (en) * | 2021-02-05 | 2022-07-08 | 浙江工业大学 | Magnetic field detection system and method |
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