A biological magnetic bead detection device and method based on magnetoelectric composite material sensor

Abstract

The present invention discloses a biological magnetic bead detection device and method based on a magnetoelectric composite material sensor, comprising a processing display unit, a detection silicon plate placement port, a packaging shell, a rotating bracket, a permanent magnet, a sensor, a motor and a conductive slip ring; the processing display unit and the detection silicon plate placement port are arranged outside the packaging shell; the rotating bracket and the motor are arranged inside the packaging shell, and the rotating bracket is connected to the motor; the conductive slip ring, the permanent magnet and the sensor are all arranged on the rotating bracket, the permanent magnet is symmetrically arranged on both sides of the sensor, and the sensor is placed below the detection silicon plate placement port; the signal output end of the sensor is connected to the conductive slip ring and the signal processing display unit in sequence. Direct contact between the magnetic beads and the sensor is avoided, the influence of the magnetic beads on the surface quality of the sensor is reduced, the sensor can be used multiple times, and the problem that the magnetic beads are modified on the sensor surface, the quality of the sensor surface is damaged, and the sensor needs to be replaced multiple times in the prior art is solved.

Description

Technical Field

[0001] The invention belongs to the field of biological detection, and relates to a biological magnetic bead detection device and method based on a magnetoelectric composite material sensor. Background Art

[0002] Biosensors are devices or apparatuses used to detect biological molecules and pathogens. They have shown great application value in the fields of disease marker detection, environmental pollution analysis, and instant food pollution detection. Among them, magnetic biosensors use superparamagnetic nanoparticles (magnetic beads for short) as magnetic markers. Superparamagnetic particles have unique magnetic properties such as superparamagnetism and high coercivity, and can be easily functionalized with different biochemical substances. They can be used to capture DNA, proteins, enzymes, and cells. The physical and chemical stability enables them to be detected and magnetically manipulated in vitro and in vivo without affecting biological interactions. These characteristics make them widely used in biomedical fields such as biological separation and detection.

[0003] Nanomagnetic beads coupled with specific biological molecules will generate a fringe magnetic field when subjected to an external magnetic field. The strength of this fringe magnetic field is proportional to the number of nanomagnetic beads, and thus proportional to the content of biological molecules. By detecting the size of this magnetic field, the concentration of pathogens can be detected.

[0004] Compared with other biomolecule detection methods (such as fluorescence and electrochemical methods), biosensors composed of magnetic sensors and nanomagnetic beads can detect the biomolecules to be tested at very low sample concentrations and have a wide linear dynamic range.

[0005] Based on this method, new methods for detecting biomolecules based on giant magnetoresistance sensors, anisotropic magnetoresistive ring sensors, Hall sensors, etc. have emerged. The most widely used is the GMR biosensor, but in most applications, the bioreceptors are directly modified on the sensor surface, and the reuse of the sensor always involves a complex process. After the detection is completed, the sensor must be cleaned, etc., which increases the workload on the one hand, and on the other hand, contact detection has a certain impact on the surface quality of the sensor. Therefore, GMR sensors are generally used as consumables and can only be used once, with high detection costs and low economic benefits. As far as the detection of biomolecules and pathogens is concerned, in addition to paying attention to basic performance such as high efficiency, high sensitivity and high reliability, ease of use, environment and cost-friendliness are also important criteria. Therefore, this puts forward requirements for non-contact detection of biomarkers.

[0006] The above scenarios require the development of suitable detection equipment to detect biomolecules labeled with magnetic nanoparticles in a non-contact manner. This will also solve the problem that some sensors can only be used once or require frequent removal of nanomagnetic beads from the sensor surface. Summary of the invention

[0007] The purpose of the present invention is to solve the problems in the prior art and to provide a biomagnetic bead detection device and method based on a magnetoelectric composite material sensor.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A biological magnetic bead detection device based on a magnetoelectric composite material sensor, comprising a signal processing module, a detection silicon plate placement port, a packaging shell, a rotating bracket, a permanent magnet, a sensor and a conductive slip ring;

[0010] The signal processing module and the detection silicon board placement port are arranged outside the packaging shell;

[0011] The rotating bracket and the motor are arranged inside the packaging shell, the conductive slip ring, the permanent magnet and the sensor are all arranged on the rotating bracket, the permanent magnet is symmetrically arranged on both sides of the sensor, and the sensor is placed below the detection silicon plate placement port;

[0012] The signal output end of the sensor is connected to a conductive slip ring and a signal processing module in sequence.

[0013] A further improvement of the present invention is:

[0014] The output end of the signal processing module is connected to a display;

[0015] The display is arranged on the top of the packaging shell, and the signal processing module is arranged inside the display.

[0016] The rotating bracket comprises a conductive slip ring bracket and a sensor bracket;

[0017] The conductive slip ring bracket is connected to a motor, the motor drives the conductive slip ring bracket to rotate, and the sensor bracket is arranged on one side of the conductive slip ring bracket;

[0018] The conductive slip ring is arranged on a conductive slip ring bracket, and the permanent magnet and the sensor are arranged on a sensor bracket.

[0019] The signal output end of the sensor is connected to the conductive slip ring and the signal processing module in sequence through a signal line, and the end surface of the sensor bracket and the inside of the display are both provided with signal line vias.

[0020] The sensor comprises two magnetostrictive layers at an upper end and a lower end and a piezoelectric layer arranged between the two magnetostrictive layers.

[0021] The magnetostrictive layer has a length of 30 mm and a width of 2.5 mm; the piezoelectric layer has a length of 12 mm and a width of 2.5 mm.

[0022] The distance between the two permanent magnets is 70 mm.

[0023] The permanent magnet is a neodymium iron boron permanent magnet.

[0024] The permanent magnet is a cylindrical structure with a diameter of 12 mm and a height of 14 mm.

[0025] A biomagnetic bead detection method based on a magnetoelectric composite material sensor comprises the following steps:

[0026] The silicon plate to be detected coupled with biological molecules and magnetic beads is placed on the detection silicon plate placement port, and the rotating bracket rotates. When the sensor rotates to the lower part of the detection silicon plate placement port, the permanent magnet will magnetize the magnetic beads on the silicon plate to be detected, so that the magnetic field of the sensor generates a charge signal. At the same time, the sensor transmits the generated charge signal to the signal processing module through the conductive slip ring;

[0027] The signal processing module detects the charge signal and obtains the detection result.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The invention discloses a biological magnetic bead detection device based on a magnetoelectric composite material sensor. A signal processing module and a detection silicon plate placement port are arranged outside a device packaging shell, a rotating bracket is arranged inside the packaging shell, a sensor and a permanent magnet are arranged on the rotating bracket, the sensor and the placement port of the detection silicon plate are arranged correspondingly, and rotating the rotating bracket can drive the permanent magnet and the sensor to rotate. When the sensor rotates to the vicinity of the placement port of the silicon plate to be detected, the permanent magnet will magnetize the magnetic beads on the silicon plate to be detected, and the sensor will then generate a corresponding magnetic field change and generate a charge signal. The charge line signal of the sensor is transmitted to the signal processing module through a conductive slip ring to realize the detection of the biological magnetic beads. Detection can be achieved by placing the silicon plate to be tested on the placement port of the detection silicon plate, avoiding direct contact between the magnetic beads and the sensor, reducing the influence of the magnetic beads on the surface quality of the sensor, and the sensor can be used multiple times. The device disclosed in the present invention rotates the sensor to convert the DC magnetic field generated by the magnetic beads on the silicon plate to be tested into an alternating magnetic field, thereby improving the detection limit and sensitivity of the sensor. At the same time, a permanent magnet is provided to replace the excitation coil to provide a bias magnetic field, which reduces the space occupancy rate to a certain extent. At the same time, the permanent magnet does not require an additional power supply to work, there is no heat generation phenomenon due to long-term operation, and the measurement error caused by temperature is also reduced. The permanent magnet and the sensor cooperate to serve as a sensitive element for weak magnetic fields, with high detection stability, good low-frequency response effect, and high resolution.

[0030] Furthermore, the processing display unit of the present invention includes a display and a signal processing module, and the display facilitates intuitive display of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is the overall structure diagram of the present invention;

[0033] Figure 2 is a cross-sectional view of the present invention;

[0034] Figure 3 Another perspective structural diagram of the present invention;

[0035] Figure 4 It is a structural diagram of the internal rotating support of the present invention;

[0036] Figure 5 This is a structural diagram of the sensor of the present invention.

[0037] Among them: 1-display; 2-detection silicon plate placement port; 3-packaging shell; 4-signal processing module; 5-rotating bracket; 6-permanent magnet; 7-sensor; 8-motor; 9-signal line via; 10-threaded hole; 11-conductive slip ring bracket; 12-sensor bracket; 13-magnetostrictive layer; 14-epoxy resin; 15-piezoelectric layer; 16-conductive slip ring. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0045] See also Figure 1-4 The embodiment of the present invention discloses a biological magnetic bead detection device based on a magnetoelectric composite material sensor, in which a layered magnetoelectric composite material sensor and a permanent magnet generating a bias magnetic field are placed on a bracket and driven by a motor to rotate at a certain frequency, and the magnetic beads of the biological sample to be detected are coupled to a fixed position above the sensor. When the sensor rotates to the bottom of the magnetic beads, the magnetic beads are magnetized by the rotating permanent magnet, thereby generating a magnetic field signal with the same frequency as the motor rotation, and this signal is sensed by the sensor, thereby realizing the detection of the biological magnetic beads.

[0046] The embodiment of the present invention includes a display 1; a detection silicon plate placement port 2; a packaging shell 3; a signal processing module 4; a rotating bracket 5; a permanent magnet 6; a sensor 7; a motor 8; a signal line via 9; a threaded hole 10; a conductive slip ring bracket 11; a sensor bracket 12; a magnetostrictive layer 13; an epoxy resin 14; a piezoelectric layer 15 and a conductive slip ring 16.

[0047] The device disclosed in the present invention is provided with a display 1 on the top of the packaging shell 3, and a detection silicon plate placement port 2 is opened on one side of the display for placing the silicon plate to be detected. The user can use the sandwich immunoassay to complete the coupling of the biological molecules to be detected and the magnetic beads on the silicon plate as the sample to be tested of the device, and then place the silicon plate coupled with the biological molecules and the magnetic beads at the detection silicon plate placement port 2 of the device for detection.

[0048] A signal processing module 4 is arranged inside the display 1; a conductive slip ring bracket 11 is arranged inside the packaging shell 3, a threaded hole 10 is opened on the conductive slip ring bracket 11, the conductive slip ring bracket 11 is rotatably connected to the motor 8 through the threaded hole 10, one side of the conductive slip ring bracket 11 is connected to the sensor bracket 12, a conductive slip ring 16 is arranged on the upper end of the conductive slip ring bracket 11, the conductive slip ring 16 is fixedly connected to the conductive slip ring bracket 11 by bolts, the input end of the conductive slip ring 16 rotates with the rotating bracket 5, and the output end is stationary relative to the housing of the device, thereby solving the wiring problem between the rotating sensor 7 and the stationary signal processing module 4.

[0049] A sensor 7 is arranged on the sensor bracket 12 , and permanent magnets 6 are arranged on both sides of the sensor 7 . The distance between the two permanent magnets 6 and the size of the bias magnetic field can be adjusted according to actual needs. The sensor 7 corresponds to the detection silicon plate placement opening 2 .

[0050] A plurality of signal line holes 9 are provided on the sensor bracket 12, and a signal line hole 9 is also provided at the bottom of the display 1. The signal output end of the sensor 7 is connected to the input end of the conductive slip ring 16 through a signal lead-out line, and the output end of the conductive slip ring 16 is connected to the input end of the signal processing module 4 through a signal lead-out line. The signal line holes 9 are arranged according to the lines of the signal lead-out lines.

[0051] The signal processing module 4 in the embodiment of the present invention is connected to the output end of the conductive slip ring 16 by leading out an SMA interface, the weak charge amount output by the sensor 7 is amplified, and then a certain filtering process is performed, and displayed to the user, the signal processing module 4 includes a charge amplifier, a low-pass filter and a detection unit, the input end of the charge amplifier is connected to the output end of the sensor 7 through the conductive slip ring 16, so as to realize the amplification of the weak signal output by the sensor, the output end of the charge amplifier is connected to the low-pass filter, and the low-pass filter is used to filter out the power frequency interference of 50Hz, and the embodiment of the present invention uses a fourth-order Chebyshev low-pass filter with a cut-off frequency of 15Hz. The other end of the low-pass filter is connected to the display 1, which is used to display the number information of the magnetic beads marked with the biological sample to be detected. The charge amplifier first amplifies the signal output by the sensor 7, and then filters it through the low-pass filter to generate a voltage signal, and finally detects the voltage signal through the detection unit to obtain the number of magnetic beads or the concentration information of biological molecules, and finally displays it through the display 1.

[0052] See also Figure 5 The sensor 7 disclosed in the embodiment of the present invention includes a magnetostrictive layer 13 and a piezoelectric layer 15. The piezoelectric layer 15 is provided with two layers, the upper and lower layers. After the piezoelectric layer 15 is polarized in the thickness direction, the upper and lower surfaces are coated with conductive silver paste, and the interdigitated electrodes are adhered. The piezoelectric layer 15 and the magnetostrictive layer 13 are bonded together by epoxy resin 14. Among them, the length of the magnetostrictive layer 13 is 30mm and the width is 2.5mm. The magnetostrictive layer 13 is formed by bonding 4 layers of Metglas by epoxy resin 14. The piezoelectric layer 15 is cut by PZT piezoelectric ceramics. The length of the piezoelectric layer 15 is 12mm, the width is 2.5mm, and the thickness is 0.6mm. Among them, Metglas, as a magnetostrictive material, will generate strain after induction of the magnetic field. After this strain is transmitted to the piezoelectric ceramic PZT, a corresponding charge is generated. The amount of charge also indicates the size of the induced magnetic field. According to the nonlinear response of Metglas to the magnetic field, it has a point that is most sensitive to the change of the magnetic field. The magnetic field size at this point is its optimal bias magnetic field. Therefore, the magnetoelectric composite material sensor usually works in a certain DC bias magnetic field. Among them, the magnetoelectric composite material sensor works in LT mode, that is, the sensitive direction of the magnetostrictive material layer is along the length direction, and the piezoelectric layer is polarized along the thickness direction.

[0053] The permanent magnet 6 disclosed in the embodiment of the present invention is a neodymium iron boron permanent magnet. The permanent magnet 6 is a circular structure with a diameter of 12 mm and a thickness of 14 mm. The distance between the two permanent magnets 6 is 70 mm, which can provide an optimal bias magnetic field for the sensor 7. The present invention uses the permanent magnet 6 to replace the conventional excitation coil to provide the bias magnetic field, thereby reducing the volume and working without an additional power supply. The permanent magnet 6 replaces the traditional energized coil to provide the bias magnetic field of the sensor, so it is a passive device, there is no heating phenomenon due to long-term operation, and there is no measurement deviation caused by temperature.

[0054] The embodiment of the present invention discloses a biomagnetic bead detection method based on a magnetoelectric composite material sensor.

[0055] The silicon plate with coupled biomolecules and magnetic beads is placed at the detection silicon plate placement port 2 of the device. After the device is started, the motor 8 rotates at a fixed speed of 300r / min (5Hz). Each time the sensor bracket 12 rotates to the vicinity of the lower part of the magnetic beads, the permanent magnet 6 on the sensor bracket 12 will magnetize the magnetic beads, and the magnetic field around the sensor 7 working in the optimal bias magnetic field will change slightly, causing the magnetostrictive layer 13 of the sensor 7 to produce deformation along the length direction with the same frequency as the rotation of the motor 8. This deformation is transmitted to the middle piezoelectric layer 15. The piezoelectric layer 15 produces electric polarization along the thickness direction due to the piezoelectric effect, thereby generating a charge signal with the same frequency as the rotation in the thickness direction. Therefore, this device can convert the magnetic field generated by the magnetic beads into a charge signal. The charge signal is transmitted to the signal processing module 4 through the signal lead line. The charge signal is preliminarily processed by the charge amplifier and the low-pass filter in the signal processing module 4 to generate a voltage signal. Finally, the voltage signal is detected to obtain the detection result, and the detection result is displayed on the display 1.

[0056] In the embodiment of the present invention, the magnetic beads are carried by a silicon plate, and the surface of the silicon plate is chemically modified and the capture antibody is modified by sandwich immunoassay to achieve specific binding of the molecule to be tested with the capture antibody and the labeled antibody, and to achieve specific binding of the magnetic beads with the labeled antibody, thereby achieving coupling of the biological molecules with the magnetic beads and fixing them on the silicon plate.

[0057] The embodiment of the present invention utilizes the sensitivity of the magnetoelectric composite material sensor to the alternating magnetic field. The DC magnetic field of the magnetic beads is converted into an alternating magnetic field by rotation, so that the detection limit and sensitivity of the sensor 7 to the magnetic beads can be improved. Since the rotation speed of the motor 8 is too large, it will cause excessive centrifugal force. Therefore, in actual operation, the rotation frequency of the motor 8 is controlled at about 5Hz, and the low-frequency characteristics of the magnetoelectric composite material sensor are utilized. One of the examples of the present invention is to use a fourth-order Chebyshev low-pass filter with a cut-off frequency of 15Hz. The other end of the low-pass filter is connected to the display 1, which is used to display the detected number information of the magnetic beads marked with the biological sample to be detected.

[0058] The embodiment of the present invention uses a magnetoelectric composite material sensor as a sensitive element for weak magnetic fields, which has good stability, good low-frequency response, and high resolution. It is easy to use, and only needs to put the silicon plate with biomagnetic beads fixed into the corresponding detection port of the device. The non-contact detection reduces the impact on the surface quality of the sensor 7 and ensures the accuracy of the detection. The sensor, as an internal element of the device, does not need to be replaced and can be used multiple times, with low cost.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A biomagnetic bead detection device based on a magnetoelectric composite material sensor, characterized in that: It comprises a signal processing module (4), a detection silicon plate placement port (2), a packaging shell (3), a rotating bracket (5), a permanent magnet (6), a sensor (7) and a conductive slip ring (16); The signal processing module (4) and the detection silicon board placement opening (2) are arranged outside the packaging shell (3); The rotating bracket (5) and the motor (8) are arranged inside the packaging shell (3); the conductive slip ring (16), the permanent magnet (6) and the sensor (7) are all arranged on the rotating bracket (5); the permanent magnet (6) is symmetrically arranged on both sides of the sensor (7); and the sensor (7) is placed below the detection silicon plate placement opening (2); The signal output end of the sensor (7) is connected in sequence to a conductive slip ring (16) and a signal processing module (4); The signal processing module (4) comprises a charge amplifier, a low-pass filter and a detection unit, the input end of the charge amplifier is connected to the output end of the sensor (7) via a conductive slip ring (16), the output end of the charge amplifier is connected to the low-pass filter, and the other end of the low-pass filter is connected to a display 1 for displaying information on the number of magnetic beads detected that are marked with a biological sample to be detected; The low-pass filter is a fourth-order Chebyshev low-pass filter with a cut-off frequency of 15 Hz.

2. A biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 1, characterized in that: The output end of the signal processing module (4) is connected to the display (1); The display (1) is arranged on the top of the packaging shell (3), and the signal processing module (4) is arranged inside the display (1).

3. A biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 2, characterized in that: The rotating bracket (5) comprises a conductive slip ring bracket (11) and a sensor bracket (12); The conductive slip ring bracket (11) is connected to the motor (8), the motor (8) drives the conductive slip ring bracket (11) to rotate, and the sensor bracket (12) is arranged on one side of the conductive slip ring bracket (11); The conductive slip ring (16) is arranged on a conductive slip ring bracket (11), and the permanent magnet (6) and the sensor (7) are arranged on a sensor bracket (12).

4. A biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 3, characterized in that: The signal output end of the sensor (7) is connected to the conductive slip ring (16) and the signal processing module (4) in sequence through a signal line, and the end surface of the sensor bracket (12) and the interior of the display (1) are both provided with a signal line via (9).

5. The biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 1, characterized in that: The sensor (7) comprises two magnetostrictive layers (13) at the upper end and the lower end, and a piezoelectric layer (15) arranged between the two magnetostrictive layers (13).

6. A biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 5, characterized in that: The magnetostrictive layer (13) has a length of 30 mm and a width of 2.5 mm; the piezoelectric layer (15) has a length of 12 mm and a width of 2.5 mm.

7. The biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 1, characterized in that: The distance between the two permanent magnets (6) is 70 mm.

8. The biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 7, characterized in that: The permanent magnet (6) is a neodymium iron boron permanent magnet.

9. A biomagnetic bead detection device based on a magnetoelectric composite material sensor according to claim 8, characterized in that: The permanent magnet (6) is a cylindrical structure with a diameter of 12 mm and a height of 14 mm.

10. The biomagnetic bead detection method based on a magnetoelectric composite material sensor according to claim 1, characterized in that: The following steps are involved: The silicon plate to be detected coupled with biological molecules and magnetic beads is placed on the detection silicon plate placement port (2), and the rotating bracket (5) is rotated. When the sensor (7) is rotated to the lower part of the detection silicon plate placement port (2), the permanent magnet (6) will magnetize the magnetic beads on the silicon plate to be detected, so that the magnetic field of the sensor (7) generates a charge signal. At the same time, the sensor (7) transmits the generated charge signal to the signal processing module (4) through the conductive slip ring (16); The signal processing module (4) detects the charge signal and obtains the detection result.

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