Magnetic particle detection system and detection method

Abstract

The invention provides a magnetic particle detection system and method, and the system comprises a refrigeration device which is used for providing an ultralow-temperature working environment for a magnetic sensor; the magnetic sensor is arranged in the refrigeration device and used for sensing the magnetic field of the magnetic particles; the control circuit is arranged outside the refrigeration device, is electrically connected with the magnetic sensor, and is used for controlling the magnetic sensor to work and reading a signal sensed by the magnetic sensor; the magnetic shielding device is arranged outside the refrigeration device and shields external environment noise; the transmission device is arranged below the refrigerating device, penetrates through the magnetic shielding device and is used for conveying a sample to be detected; the magnetizing device is arranged in the magnetic shielding device and is positioned in the detection range of the magnetic sensor, or is arranged outside the magnetic shielding device and is positioned at the end part of the transmission device; the invention provides an excitation magnetic field for magnetizing a to-be-tested sample. Based on the low-temperature SQUID, the magnetic nanoparticles and the magnetic micron-sized particles can be detected, the sensitivity is high, the signal-to-noise ratio is high, and the detection range is large.

Description

Technical Field

[0001] This invention relates to the field of magnetic signal detection, and in particular to a magnetic particle detection system and method. Background Technology

[0002] In recent years, the detection of magnetic particles has become increasingly important. Whether in the processing of food, batteries, or other industrial products, those skilled in the art have made great efforts to avoid contaminants as much as possible. However, contaminants may still accidentally get into food or batteries, such as small metal shavings or fine metal wires from machining.

[0003] Current methods for detecting magnetic particles primarily target micron-sized particles, with very few applications for detecting magnetic nanoparticles. Furthermore, existing magnetic particle detection devices generally suffer from poor sensitivity and limited detection range. Therefore, developing a highly sensitive, wide-range detection device suitable for both micron-sized and nanoparticles has become a pressing issue for those skilled in the art.

[0004] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a magnetic particle detection system and detection method to solve the problems of poor sensitivity, small detection range, and inability to detect magnetic nanoparticles in the prior art magnetic particle detection devices.

[0006] To achieve the above and other related objectives, the present invention provides a magnetic particle detection system, wherein the magnetic particle detection device comprises at least:

[0007] Refrigeration unit, magnetic sensor, control circuit, magnetic shielding device, transmission device and magnetization device;

[0008] The cooling device is used to provide an ultra-low temperature operating environment for the magnetic sensor;

[0009] The magnetic sensor is installed inside the cooling device and is used to sense the magnetic field of magnetic particles.

[0010] The control circuit is located outside the refrigeration device and is electrically connected to the magnetic sensor. It is used to control the operation of the magnetic sensor and read the signal sensed by the magnetic sensor.

[0011] The magnetic shielding device is located outside the refrigeration device to shield against external environmental noise.

[0012] The transmission device is located below the cooling device and passes through the magnetic shielding device, and is used to transport the sample to be tested;

[0013] The magnetizing device is disposed inside the magnetic shielding device and within the detection range of the magnetic sensor; or the magnetizing device is disposed outside the magnetic shielding device and at the end of the transmission device; the magnetizing device is used to provide an excitation magnetic field to magnetize the sample to be tested.

[0014] Optionally, the refrigeration device is a Dewar.

[0015] Optionally, the magnetic sensor is a second-order SQUID axial gradient meter.

[0016] Optionally, the magnetic shielding device has an inlet at the top for placing the cooling device; the magnetic shielding device has two conveying ports on its lower side wall, through which the transmission device passes.

[0017] Alternatively, the material of the magnetic shielding device may include permalloy, iron, nickel, cobalt, or manganese-zinc ferrite.

[0018] Optionally, the transmission device may be made of aluminum profiles and / or wood.

[0019] Optionally, the magnetizing device is a Helmholtz coil.

[0020] Optionally, the magnetic particle detection system further includes a signal processing device; the signal processing device is connected to the control circuit and processes and analyzes the signal read by the control circuit.

[0021] To achieve the above and other related objectives, the present invention also provides a method for detecting magnetic particles, the method comprising at least:

[0022] 11) The above-mentioned magnetic particle detection system is provided, wherein the magnetization device is disposed inside the magnetic shielding device and is located within the detection range of the magnetic sensor;

[0023] 12) The magnetic nanoparticle-modified sample to be tested is transported to the detection range of the magnetic sensor via a transmission device and then fixed in place;

[0024] 13) The magnetization device is powered on to magnetize the magnetic nanoparticles, and the magnetization device is turned off after the magnetization is completed;

[0025] 14) Collect particle signals after the dead time and analyze the collected information.

[0026] To achieve the above and other related objectives, the present invention also provides a method for detecting magnetic particles, the method comprising at least:

[0027] 21) The above-mentioned magnetic particle detection system is provided, wherein the magnetization device is disposed outside the magnetic shielding device and located at the end of the transmission device;

[0028] 22) The sample to be tested, modified with magnetic micron-sized particles, is placed within the magnetization range at the end of the transmission device. The magnetization device is powered on to magnetize the magnetic micron-sized particles. After magnetization is completed, the magnetization device is turned off.

[0029] 23) The sample to be tested is transported through the transmission device, and particle signals are collected;

[0030] 24) Analyze the collected particle signals and locate the trajectory of the magnetic micron-sized particles, and compare the motion state of the transmission device to verify the accuracy of the magnetic micron-sized particle positioning.

[0031] As described above, the magnetic particle detection system and method of the present invention have the following beneficial effects:

[0032] 1. The magnetic particle detection system of the present invention can switch between the detection of magnetic micron particles and the detection of magnetic nanoparticles by moving the position of the magnetization device. It is easy to operate and has a large detection range.

[0033] 2. The magnetic particle detection system of the present invention adopts low-temperature SQUID detection technology. The low-temperature SQUID sensor is currently the most sensitive magnetic sensor, which increases the reliability of detection. Compared with the existing high-temperature SQUID system, it has a larger detection range, higher efficiency, and advantages in high sensitivity and signal-to-noise ratio.

[0034] 3. The magnetic particle detection system of the present invention can easily detect magnetic particles by placing the sample to be tested on the transmission device, and is easy to operate.

[0035] 4. The magnetic particle detection system of the present invention uses non-contact detection of magnetic particles and will not have any impact on the sample to be tested.

[0036] 5. The magnetic particle detection system of the present invention may optionally use an integrated gradient meter design, which improves the system integration, saves liquid helium, and improves sensitivity. Attached Figure Description

[0037] Figure 1 The diagram shown is a structural schematic of the magnetic particle detection system of the present invention.

[0038] Figure 2The diagram shows a flow chart of the magnetic particle detection system of the present invention for detecting magnetic nanoparticles.

[0039] Figure 3 This is a schematic diagram of another structure of the magnetic particle detection system of the present invention.

[0040] Figure 4 The diagram shows a flowchart of the magnetic particle detection system of the present invention for detecting magnetic micron-sized particles.

[0041] Component designation explanation

[0042] 1. Magnetic Particle Detection System

[0043] 11 Refrigeration equipment

[0044] 12 Magnetic Sensors

[0045] 13 Control Circuit

[0046] 14 Magnetic shielding device

[0047] 15. Transmission device

[0048] 16 Magnetizing device

[0049] 17. Signal processing device

[0050] 2. Samples to be tested Detailed Implementation

[0051] The following specific examples illustrate the implementation 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 also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0052] Please see Figures 1-4 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 the 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.

[0053] Several methods exist for detecting magnetic micron-sized particles, such as eddy current detectors, X-ray imaging, and high-temperature squuid-based detection systems. Eddy current detectors are widely used in food safety testing and other industrial fields; however, their sensitivity is highly correlated with the conductivity of contaminants and food, making them difficult to use for frozen foods. X-rays are also a very useful technique, but their sensitivity is insufficient, limiting their detection to magnetic particles larger than 100 μm. High-temperature squuid-based magnetic particle detection is a non-contact and highly sensitive method that uses remanence. This involves applying a magnetizing pulse to the sample, magnetizing it, and then detecting the residual magnetic field after the magnetic field is removed. However, this device uses a magnet to magnetize the sample, resulting in uneven magnetization in magnitude and direction, which is detrimental to the quantitative detection of particle signals. Furthermore, limited by the high-temperature squuid, the device suffers from high noise, insufficient sensitivity, and a small detection range. Therefore, this device can only detect larger magnetic particles and has no ability to detect magnetic nanoparticles.

[0054] Magnetic particles include magnetic nanoparticles and particles larger than micrometers. These two types of particles have different magnetic field characteristics after magnetization, therefore their detection methods are completely different. This invention provides a magnetic particle detection system based on low-temperature SQUID. By simply moving the magnetization device, the conversion between these two detection methods can be completed. In other words, the magnetic particle detection system of this invention has the function of detecting both magnetic nanoparticles and magnetic micrometer-sized particles.

[0055] Example 1

[0056] like Figure 1 As shown, this embodiment provides a magnetic particle detection system 1, including:

[0057] Refrigeration device 11, magnetic sensor 12, control circuit 13, magnetic shielding device 14, transmission device 15 and magnetization device 16.

[0058] like Figure 1 As shown, the cooling device 11 is used to provide an ultra-low temperature operating environment for the magnetic sensor 12.

[0059] Specifically, the cooling device 11 is installed in an ultra-low temperature environment to ensure the normal operation of the low-temperature superconducting material in the magnetic sensor 12. The specific temperature is set according to the characteristics of the low-temperature superconducting material (including but not limited to the critical temperature). In this embodiment, the cooling device 11 is implemented using a Dewar flare, which contains liquid helium (approximately 4.2K). The Dewar flare has a high degree of vacuum and thermal insulation performance, and also has a certain electromagnetic shielding function.

[0060] like Figure 1 As shown, the magnetic sensor 12 is disposed inside the cooling device 11 and is used to sense the magnetic field of magnetic particles.

[0061] Specifically, the magnetic sensor 12 is made of low-temperature superconducting material, enabling highly sensitive magnetic field detection. It converts magnetic signals into corresponding electrical signals, exhibiting strong detection capability and a large detection range. In this embodiment, the magnetic sensor 12 is implemented using a second-order SQUID axial gradiometer. Furthermore, the second-order SQUID axial gradiometer in this invention is an integrated gradiometer. Compared with traditional second-order axial gradiometers, the integrated second-order SQUID axial gradiometer eliminates complex intermediate designs, directly integrating the gradiometer onto the chip. This reduces stray coil area, improves sensitivity, and, by integrating the chip and gradiometer together, saves liquid helium, reduces costs, and further enhances sensitivity.

[0062] like Figure 1 As shown, the control circuit 13 is located outside the cooling device 11 and is electrically connected to the magnetic sensor 12. It is used to control the operation of the magnetic sensor 12 and read the signal sensed by the magnetic sensor 12.

[0063] Specifically, the control circuit 13 is electrically connected to the magnetic sensor 12 in the cooling device 11 through a wire to realize functions including but not limited to power-on, reset, heating, adjustment, and reading. Any circuit structure that can control the magnetic sensor 12 to work normally and read the magnetic signal sensed by the magnetic sensor 12 is applicable to the present invention, and will not be described in detail here.

[0064] In another implementation of the present invention, the magnetic particle detection system 1 further includes a signal processing device 17. The signal processing device 17 is connected to the control circuit 13 and processes and analyzes the signals read from the control circuit 13.

[0065] like Figure 1 As shown, the magnetic shielding device 14 is located outside the cooling device 11 to shield external environmental noise.

[0066] Specifically, in this embodiment, the magnetic shielding device 14 has a cuboid structure with an entrance at its top for placing the cooling device 11, i.e., the cooling device 11 is placed into the magnetic shielding device 14 through the entrance. In addition, two conveying ports are provided on the lower side wall of the magnetic shielding device 14, and the transmission device 15 passes through the two conveying ports and then through the magnetic shielding device 14; in this example, the two conveying ports are arranged opposite each other and are located on the left and right side walls of the magnetic shielding device 14, respectively.

[0067] Specifically, the magnetic shielding device 14 should be made of a material with the highest possible relative permeability. For example, the relative permeability of the magnetic shielding device 14 is not less than 100. Specific materials include, but are not limited to, iron, nickel, cobalt and their alloys, permalloy, and manganese-zinc ferrite, which will not be described in detail here. In actual use, any material that can shield external noise and ensure the normal operation of the magnetic particle detection system of the present invention is applicable and is not limited to this embodiment.

[0068] like Figure 1 As shown, the transmission device 15 is located below the cooling device 11 and passes through the magnetic shielding device 15, and is used to transport the sample 2 to be tested.

[0069] Specifically, in this embodiment, the transmission device 15 is implemented using a conveyor belt, which is driven by a motor. To further reduce interference, the material of the transmission device 15 of the present invention should be selected as a material with low or even no magnetic properties, including but not limited to aluminum profiles and wood; in actual use, any material that does not affect the normal operation of the magnetic particle detection system of the present invention is applicable, and is not limited to this embodiment.

[0070] like Figure 1 As shown, the magnetization device 16 is used to provide an excitation magnetic field to magnetize the sample 2 to be tested.

[0071] Specifically, in this embodiment, the magnetization device 16 is disposed inside the magnetic shielding device 14 and is located within the detection range of the magnetic sensor 12, thereby achieving full magnetization of the sample 2 to be tested within the detection range of the magnetic sensor 12.

[0072] Specifically, in this embodiment, the magnetization device 16 is implemented using a Helmholtz coil. A Helmholtz coil can provide a controllable uniform field (i.e., a magnetic field of the same magnitude and direction within a certain range). The uniform field generated by the Helmholtz coil in all directions ensures that the magnetization direction of the magnetic particles is consistent, and magnetization can be accurately performed from all directions to explore the most suitable direction for magnetic particle detection. When dealing with complex test samples 2 (such as those requiring the detection of multiple magnetic particles), if the magnetization direction and magnitude are not uniform, it will cause the magnetic fields of each particle to cancel each other out, weakening the magnetic field of the test sample and hindering detection. Moreover, a Helmholtz coil is almost non-magnetic when no current is flowing through it; therefore, directly turning off the current after magnetization can reduce the impact of the magnetization device on SQUID noise. In practical applications, other magnetization devices can also be used, including but not limited to electromagnets, DC excitation devices, solenoids, etc., which will not be elaborated here.

[0073] The magnetic field of magnetic nanoparticles decays very rapidly after magnetization, completely decaying within seconds or even hundreds of milliseconds. This phenomenon is called relaxation in physics. After magnetization, the relaxation signal of the magnetic nanoparticles can be detected by starting signal acquisition only after a certain dead time (tens of milliseconds). Quantitative analysis of the detection results can yield information on the quantity and location of the magnetic nanoparticles. Therefore, the magnetic particle detection system of this embodiment can be used to detect magnetic nanoparticles, such as... Figure 2 As shown, the specific testing process is as follows:

[0074] 11) Provides the magnetic particle detection system 1 of this embodiment.

[0075] 12) The magnetic nanoparticle-modified sample 2 is transported to the detection range of the magnetic sensor 12 via the transmission device 15 and then fixed in place.

[0076] Specifically, the sample to be tested 2 is placed at one end of the transmission device 15, and the transmission device 15 is started to transport the sample to be tested 2 into the magnetic shielding device 14, and it is located within the detection range below the magnetic sensor 12; the transmission device 15 is stopped so that the position of the sample to be tested 2 remains fixed.

[0077] 13) Power on magnetization device 16 to magnetize the magnetic nanoparticles, and turn off magnetization device 16 after magnetization is completed.

[0078] 14) Collect particle signals after the dead time and analyze the collected information.

[0079] Specifically, signals are acquired after the dead time to obtain the relaxation signals of the magnetic nanoparticles. As one example, a signal is acquired once and analyzed; as another example, two or more signals are acquired, the acquired signals are averaged, and then the averaged signals are analyzed.

[0080] Example 2

[0081] like Figure 3 As shown, this embodiment provides a magnetic particle detection system 1, which differs from the first embodiment in that the magnetization device 16 is disposed outside the magnetic shielding device 14 and located at the end of the transmission device 15.

[0082] Specifically, the magnetization device 16 is located at the end of the transmission device 15 and fully magnetizes the sample 2 to be tested outside the detection range of the magnetic sensor 12.

[0083] It should be noted that the other structures of the magnetic particle detection system 1 are the same as those in Embodiment 1, and will not be described in detail here.

[0084] The relaxation time of magnetic particles is positively correlated with their volume. Therefore, micron-sized magnetic particles have a long relaxation time, and the magnetic field decays slowly after magnetization, making it impossible to detect their magnetism by detecting the decaying magnetic field. Since SQUIDs are not sensitive to static magnetic fields, it is necessary to move the micron-sized magnetic particles. In this embodiment, the magnetic particle detection system 1 places the magnetic particles on a conveying device 15 for magnetization. After magnetization, the conveying device 15 is activated, causing the magnetic particles to move under the magnetic sensor 12 to generate a changing magnetic field, which can then be detected. Figure 4 As shown, the specific testing process is as follows:

[0085] 21) Provides the magnetic particle detection system 1 of this embodiment.

[0086] 22) Place the test sample 2 modified with magnetic micron-sized particles into the magnetization range at the end of the transmission device 15, power on the magnetization device 16 to magnetize the magnetic micron-sized particles, and turn off the magnetization device 16 after magnetization is completed.

[0087] Specifically, the sample to be tested 2 is placed at one end of the transmission device 15, and the transmission device 15 is not started; then the magnetization device 16 is powered on to fully magnetize the sample to be tested 2, and finally the magnetization device 16 is turned off; during this process, the position of the sample to be tested 2 remains unchanged.

[0088] 23) The sample 2 to be tested is transported through the transmission device 15 to collect particle signals.

[0089] 24) Analyze the collected particle signals and locate the motion trajectory of the magnetic micron-sized particles. Compare the motion state of the transmission device 15 to verify the accuracy of the magnetic micron-sized particle positioning.

[0090] Specifically, the Levenberg-Marquardt (LM) algorithm can be used to determine the position information of the magnetic field of the magnetic particles, thus enabling the localization of the magnetic particles. Since the particles are in motion, their trajectories can also be obtained. These trajectories are then compared with the trajectory of the transmission device 15 to improve accuracy.

[0091] In summary, this invention provides a magnetic particle detection system and method, comprising: a cooling device, a magnetic sensor, a control circuit, a magnetic shielding device, a transmission device, and a magnetizing device. The cooling device provides an ultra-low temperature operating environment for the magnetic sensor. The magnetic sensor is disposed within the cooling device and is used to sense the magnetic field of magnetic particles. The control circuit is disposed outside the cooling device and electrically connected to the magnetic sensor, used to control the operation of the magnetic sensor and read the signal sensed by the magnetic sensor. The magnetic shielding device is disposed outside the cooling device and is used to shield against external environmental noise. The transmission device is disposed below the cooling device and penetrates the magnetic shielding device, used to transport the sample to be tested. The magnetizing device is disposed inside the magnetic shielding device and is located within the detection range of the magnetic sensor; or the magnetizing device is disposed outside the magnetic shielding device and is located at the end of the transmission device. The magnetizing device provides an excitation magnetic field to magnetize the sample to be tested. This invention, based on low-temperature SQUID, can achieve the detection of magnetic nanoparticles and magnetic micron-sized particles with high sensitivity, high signal-to-noise ratio, and large detection range. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0092] 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 magnetic particle detection system, characterized in that, The magnetic particle detection device includes at least: Refrigeration unit, magnetic sensor, control circuit, magnetic shielding device, transmission device and magnetization device; The cooling device is used to provide an ultra-low temperature operating environment for the magnetic sensor; The magnetic sensor is installed inside the cooling device and is used to sense the magnetic field of magnetic particles. The control circuit is located outside the refrigeration device and is electrically connected to the magnetic sensor. It is used to control the operation of the magnetic sensor and read the signal sensed by the magnetic sensor. The magnetic shielding device is located outside the refrigeration device to shield against external environmental noise. The transmission device is located below the cooling device and passes through the magnetic shielding device, and is used to transport the sample to be tested; The magnetizing device is disposed inside the magnetic shielding device and is located within the detection range of the magnetic sensor; or The magnetizing device is disposed outside the magnetic shielding device and located at the end of the transmission device; the magnetizing device is used to provide an excitation magnetic field to magnetize the sample to be tested.

2. The magnetic particle detection system according to claim 1, characterized in that: The refrigeration device is a Dewar.

3. The magnetic particle detection system according to claim 1, characterized in that: The magnetic sensor is a second-order SQUID axial gradient meter.

4. The magnetic particle detection system according to claim 1, characterized in that: The magnetic shielding device has an entrance at the top for placing the cooling device; the magnetic shielding device has two conveying ports on its lower side wall, through which the transmission device passes.

5. The magnetic particle detection system according to claim 1 or 4, characterized in that: The materials used in the magnetic shielding device include permalloy, iron, nickel, cobalt, or manganese-zinc ferrite.

6. The magnetic particle detection system according to claim 1, characterized in that: The transmission device is made of aluminum profiles and / or wood.

7. The magnetic particle detection system according to claim 1, characterized in that: The magnetizing device is a Helmholtz coil.

8. The magnetic particle detection system according to claim 1, characterized in that: The magnetic particle detection system also includes a signal processing device; the signal processing device is connected to the control circuit and processes and analyzes the signals read by the control circuit.

9. A method for detecting magnetic particles, characterized in that, The method for detecting magnetic particles includes at least the following: 11) A magnetic particle detection system as described in any one of claims 1-8 is provided, wherein the magnetization device is disposed inside the magnetic shielding device and is located within the detection range of the magnetic sensor; 12) The magnetic nanoparticle-modified sample to be tested is transported to the detection range of the magnetic sensor via a transmission device and then fixed in place; 13) The magnetization device is powered on to magnetize the magnetic nanoparticles, and the magnetization device is turned off after the magnetization is completed; 14) Collect particle signals after the dead time and analyze the collected information.

10. A method for detecting magnetic particles, characterized in that, The method for detecting magnetic particles includes at least the following: 21) A magnetic particle detection system as described in any one of claims 1-8 is provided, wherein the magnetization device is disposed outside the magnetic shielding device and located at the end of the transmission device; 22) The sample to be tested, modified with magnetic micron-sized particles, is placed within the magnetization range at the end of the transmission device. The magnetization device is powered on to magnetize the magnetic micron-sized particles. After magnetization is completed, the magnetization device is turned off. 23) The sample to be tested is transported through the transmission device, and particle signals are collected; 24) Analyze the collected particle signals and locate the trajectory of the magnetic micron-sized particles, and compare the motion state of the transmission device to verify the accuracy of the magnetic micron-sized particle positioning.

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