A sensor system based on flaky magnetic labels and GMR magnetic biochip

Abstract

This invention provides a sensor system based on a sheet-like magnetic tag and a GMR magnetic biochip, relating to the field of electronic information technology. The structure comprises a signal acquisition board and a chip carrier board. The biochip is mounted on the chip carrier board, which is situated within the channel of a solenoid. The solenoid is located within the mounting structure. A programmable power supply board provides power to the solenoid. The biochip can capture pathogenic bacteria modified by the sheet-like magnetic tag. The signal acquisition board is equipped with a constant current circuit and a signal acquisition circuit. The constant current circuit provides a constant current to the biochip, and the signal acquisition circuit acquires, amplifies, and processes the signal output from the biochip. This system effectively improves the sensitivity of the sensor system, enabling high-sensitivity detection of low-concentration pathogenic bacteria samples and preventing the biochip's output signal from being drowned out by background noise.

Description

Technical Field

[0001] This specification relates to the field of electronic information technology, and more specifically, to a sensor system based on sheet-like magnetic tags and GMR magnetic biochips. Background Technology

[0002] In recent years, with advancements in magnetoresistive materials and magnetic microparticles, biosensors based on the GMR effect have been developed. Highly sensitive, micrometer-scale magnetic field sensors have been fabricated using multilayer metal thin-film structures, whose resistance changes with the applied magnetic field. GMR biosensors utilize this effect to detect the presence and quantity of magnetic microparticles used for bioseparation and purification, ultimately assessing the concentration of microorganisms based on the number of these microparticles.

[0003] However, ordinary magnetic tags are small in size, with particle sizes typically on the nanometer scale. The resulting additional magnetic field strength is weak, making the effective output signal of the GMR chip very weak. That is, the signal amplitude is usually on the μV level. The effective signal is often buried in strong background noise such as power frequency noise and its harmonics, excitation signal and its harmonics, leading to inaccurate results. Summary of the Invention

[0004] The purpose of this specification is to provide a sensor system based on sheet-like magnetic tags and GMR magnetic biochips, which can solve the problem of inaccurate detection results of weak signals by traditional sensor systems.

[0005] The embodiments described in this specification are implemented as follows:

[0006] A sensor system based on sheet-like magnetic tags and GMR magnetic biochips includes a programmable power supply board, a signal acquisition board, a chip carrier board, a solenoid, and a mounting structure.

[0007] The signal acquisition board is connected to the chip carrier board, the chip carrier board is provided with a biochip, the chip carrier board is disposed in the channel of the solenoid, the solenoid is disposed in the loading structure, the programmable power board can provide power to the solenoid, and the biochip can capture pathogenic bacteria modified by sheet-like magnetic tags;

[0008] The signal acquisition board is equipped with a constant current circuit and a signal acquisition circuit. The constant current circuit can provide a constant current to the biochip, and the signal acquisition circuit can acquire and amplify the signal output by the biochip.

[0009] The embodiments described in this specification have at least the following advantages or beneficial effects:

[0010] Compared with existing technologies, this sensor system based on sheet magnetic tags and GMR magnetic biochips captures pathogens through sheet magnetic tags, and then collects the magnetically captured pathogens with the aforementioned signal acquisition board. After amplification and processing by constant current circuit and signal acquisition circuit, the sensitivity of the sensor system can be effectively improved, that is, it can perform high-sensitivity detection on low-concentration pathogen samples, and avoid the output signal of the biochip being buried in background noise. Attached Figure Description

[0011] To more clearly illustrate the technical solutions of the embodiments of this specification, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this specification and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a connection diagram of the sensor system based on sheet magnetic tags and GMR magnetic biochips provided in this manual;

[0013] Figure 2 This is a schematic diagram of the signal acquisition board provided in this manual;

[0014] Figure 3 This is a circuit diagram of the constant current circuit provided in this manual;

[0015] Figure 4 This is a circuit diagram of the signal acquisition circuit provided in this manual;

[0016] Figure 5 This is a schematic diagram of the chip carrier board provided in this specification;

[0017] Figure 6 This is a schematic diagram of the sensor system based on sheet-like magnetic tags and GMR magnetic biochips provided in this specification.

[0018] Figure 7 This is a schematic diagram of the sensor system and chip carrier based on sheet magnetic tags and GMR magnetic biochips provided in this manual.

[0019] Figure 8 This is a schematic diagram of the chip carrier board provided in this specification;

[0020] Figure 9 This is a front view of the limiting plate provided in this instruction manual;

[0021] Figure 10 This is a schematic diagram of the installation of the biochip provided in this instruction manual;

[0022] Icons: 1. Signal acquisition board; 2. Chip carrier board; 21. Electrode sheet; 3. Solenoid; 4. Loading structure; 5. Biochip; 6. Support plate; 7. Limiting plate; 8. Handle; 9. Limiting component; 10. Through groove; 11. Limiting groove; 12. Buckle; 13. Switch button; 15. Pressing component. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments in this specification clearer, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Generally, the components of the embodiments of this specification described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments provided in the accompanying drawings is not intended to limit the scope of the claimed specification, but merely represents selected embodiments of the specification. All other embodiments obtained by those skilled in the art based on the embodiments in this specification without inventive effort are within the scope of protection of this specification.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of the embodiments in this specification, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These are used only for the convenience of describing this specification and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this specification. Furthermore, the terms "first," "second," and "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of terms such as "horizontal," "vertical," and "suspended" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments in this specification, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this specification according to the specific circumstances.

[0029] Please refer to Figures 1 to 10 The sensor system based on sheet magnetic tags and GMR magnetic biochips provided in one embodiment of this specification mainly includes a programmable power supply board, a signal acquisition board 1, a chip carrier board 2, a solenoid 3, and a mounting structure 4.

[0030] The signal acquisition board 1 and the chip carrier board 2 are connected. A biochip 5 is disposed on the chip carrier board 2. The chip carrier board 2 is disposed in the channel of the solenoid 3. The solenoid 3 is disposed in the loading structure 4. The programmable power board can provide power to the solenoid 3. The biochip 5 can capture pathogens modified with sheet-like magnetic tags. The sheet-like magnetic tags can magnetically mark the pathogens.

[0031] The signal acquisition board 1 is equipped with a constant current circuit and a signal acquisition circuit. The constant current circuit can provide a constant current to the biochip 5, and the signal acquisition circuit can acquire and amplify the signal output by the biochip 5.

[0032] In this embodiment, the biochip 5 is a GMR magnetic biochip.

[0033] In this embodiment, the method for preparing the above-mentioned sheet-like magnetic tag is as follows:

[0034] A graphene substrate is prepared, wherein the uniformity of the graphene on the graphene substrate meets the preset requirements;

[0035] Magnetic iron oxide nanoparticles were prepared by synthesizing an iron oleate precursor.

[0036] After modifying magnetic iron oxide nanoparticles with sodium citrate, the modified magnetic iron oxide nanoparticles were mixed with a graphene substrate in an aqueous phase to obtain a two-dimensional flexible magnetic aggregate. The magnetic strength of the two-dimensional flexible magnetic aggregate was determined based on the loading amount of the modified magnetic iron oxide nanoparticles and the relative spacing between the modified magnetic iron oxide nanoparticles.

[0037] The detailed preparation methods for each of the above steps are as follows:

[0038] Preparation of graphene substrate: Graphene generated by chemical vapor deposition was deposited on the surface of copper foil to obtain Gr / Gu sample; polymethyl methacrylate was coated on the side of the Gr / Gu sample away from the copper foil, and after drying, PMMA / Gr / Gu sample was obtained; PMMA / Gr / Gu sample was immersed in ammonium persulfate solution, and after removing the copper foil, the floating sample on the surface of the ammonium persulfate solution was retrieved with a silicon wafer and dried to obtain PMMA / Gr / SiO2 / Si sample; PMMA / Gr / SiO2 / Si sample was immersed in acetone solvent to remove polymethyl methacrylate, and Gr / SiO2 / Si sample was obtained.

[0039] Preparation of magnetic iron oxide particles: A first mixed solution was obtained by mixing ethanol, deionized water, and n-hexane; ferric chloride hexahydrate and sodium oleate were added to the first mixed solution, and after reflux, a hexane solution containing ferric oleate was obtained; after evaporating the hexane solution containing ferric oleate, an oily mixture of ferric oleate was obtained; the oily mixture of ferric oleate, octadecene, oleic acid, or sodium oleate was heated and reacted under nitrogen atmosphere, cooled to room temperature, and then air was introduced, followed by the addition of isopropanol to obtain magnetic iron oxide nanoparticles. Specifically, the volume ratio of ethanol, deionized water, and n-hexane was 4:3:7, the volume of the first mixed solution was 100 mL, the added mass of ferric chloride hexahydrate was 2.7 g (molar mass 10 mmol), and the added mass of sodium oleate was 9.125 g (molar mass 30 mmol). The mixture was refluxed at 70℃ for 4 hours, and a reddish-brown n-hexane solution (containing ferric oleate) was obtained. This solution was washed with 10 mL of deionized water, and the hexane was evaporated to obtain the oily mixture of ferric oleate. 9 g of the oily mixture of ferric oleate, 25 g of octadecene, and a certain amount of oleic acid or sodium oleate were added to a three-necked flask. Under nitrogen atmosphere, the temperature was increased to 320℃ at a rate of 3℃ / min to 5℃ / min and held at this temperature for 30 min with stirring during the holding period. The mixture was then cooled to room temperature, air was bubbled into the flask, and 50 mL of isopropanol was added to precipitate magnetic iron oxide nanoparticles. The obtained magnetic iron oxide nanoparticles were centrifuged and washed three times (using a mixture of n-hexane and ethanol, volume ratio 1:5), and then dispersed in n-hexane or toluene for later use.

[0040] Preparation of citric acid-modified magnetic iron oxide nanoparticles: The prepared magnetic iron oxide nanoparticles were precipitated with ethanol and then dispersed in tetrahydrofuran to obtain a dispersion solution. Sodium citrate solution was added to the dispersion solution, and the reaction was carried out under nitrogen atmosphere. After centrifugation, the modified magnetic iron oxide nanoparticles were obtained. Specifically, the magnetic iron oxide nanoparticles (including spherical, sheet-like, and rod-shaped magnetic iron oxide single particles) were modified with sodium citrate on their surface via ligand exchange. Specifically, 10 mg of magnetic iron oxide single particles (spherical, sheet-like, or rod-shaped) were precipitated with ethanol and dispersed in 10 mL of tetrahydrofuran. Then, 5 mL of sodium citrate aqueous solution (sodium citrate mass 20 mg) was added, and the reaction was carried out at room temperature for 4 h under nitrogen protection. After the reaction, the modified magnetic iron oxide single particles adhered to the bottom of the reaction flask or the stir bar, were centrifuged to precipitate, and dispersed in deionized water. The modified magnetic iron oxide single particles in the aqueous phase were purified by filtration through a 0.22 μm filter membrane for later use.

[0041] Preparation of sheet-like magnetic tags: Using the functionalized molecules on the surface of the graphene substrate prepared above as coordination centers, the magnetic iron oxide nanoparticles modified with citric acid above are mixed with the graphene substrate in the aqueous phase to prepare two-dimensional flexible iron oxide, which is a sheet-like magnetic tag.

[0042] In this embodiment, the magnetic labeling of pathogenic bacteria with the above-mentioned sheet-like magnetic tag can effectively enhance the detection sensitivity of the above-mentioned sensor system for pathogenic bacteria. Furthermore, the signal acquisition board 1 amplifies the acquired pathogenic bacteria signal, which can further enhance the detection sensitivity of the above-mentioned sensor system, thereby avoiding the signal being buried in background noise.

[0043] In this embodiment, the programmable power board can provide power to the solenoid 3. By adjusting the power of the programmable power board, the current of the solenoid 3 becomes a variable current, thereby generating an excitation magnetic field for the biochip 5.

[0044] In this embodiment, the constant current circuit includes a first diode, a second diode, and a control resistor R. G and load resistance R L The first diode and the second diode are connected in series in the feedback loop D. A In this context, the range of the input signal is limited by the control resistor R. G The load resistor R L The second diode and the load resistor R are connected in series with the biochip 5 to control the output current of the current source to the biochip 5. L It is connected in parallel with the biochip 5 to stabilize the current of the biochip 5. Biochip 5

[0045] In this embodiment, feedback loop D ACapable of controlling load resistance R L Size.

[0046] In this embodiment, the constant current circuit can provide a constant current of 1μA to 20μA to the biochip 5.

[0047] In this embodiment, the first diode and the second diode are connected in series and connected in parallel with the biochip 5 to form the constant current circuit. When power is applied to the circuit, the diode provides a relatively constant voltage when it is forward conducting. Due to the voltage characteristics of the diode, the voltage across the biochip 5 remains constant, thereby enabling the current of the biochip 5 to remain relatively constant.

[0048] In this embodiment, the signal acquisition circuit includes a first-stage operational amplifier, a second-stage operational amplifier, and an AD converter. The input terminal of the first-stage operational amplifier is connected in parallel with the biochip 5, and the output terminal of the second-stage operational amplifier is connected to the AD converter. The first-stage operational amplifier can differentially amplify the voltage signal across the biochip 5. The second-stage operational amplifier can buffer and stabilize the voltage signal output by the first-stage operational amplifier and use it as the input signal of the AD converter. The AD converter can convert the received analog voltage signal into a digital signal and output it to the host computer.

[0049] In this embodiment, the first-stage operational amplifier is preferably an INA333, and the second-stage operational amplifier is preferably an OPA333, as detailed below. Figure 4 As shown.

[0050] In this embodiment, the signal acquisition circuit can amplify the input signal and process the voltage output by the biochip 5. The first-stage operational amplifier can perform high-precision differential amplification of the input signal, and the second-stage operational amplifier can buffer and stabilize the input signal, thereby acquiring and processing low-level signals.

[0051] In this embodiment, a plurality of electrode pads 21 are disposed on one side of the chip carrier 2, which can provide power to the biochip 5. Specifically, the number of electrode pads 21 is preferably seven, providing a stable power supply to the biochip 5. The chip carrier 2 provides support for the biochip 5.

[0052] In this embodiment, the loading structure 4 is provided with a mounting hole and an insertion hole on one side. The mounting hole is provided with the solenoid 3. The hole channel direction of the mounting hole is the same as that of the insertion hole, and the hole sidewall of the insertion hole abuts against the inner wall of the solenoid. The insertion hole can insert the chip carrier 2.

[0053] In this embodiment, the loading structure 4 can be a rectangular structure with dimensions of 450mm×212mm×250mm (length×width×height). A display screen is mounted on the front of the loading structure 4, and the insertion hole (i.e., a hole is provided at the housing position of the loading structure 4) is provided on the same side. The mounting hole is provided inside the loading structure 4, and a solenoid 3 is provided in the mounting hole.

[0054] In this embodiment, the aforementioned display screen can be used to display the detection human-computer interaction software.

[0055] In this embodiment, the arrangement of the insertion hole and mounting hole allows the biochip 5 mounted on the chip carrier 2 to be positioned at the center of the solenoid 3, thereby making the magnetic field strength at the location of the biochip 5 controllable. Furthermore, this arrangement facilitates the installation and removal of the chip carrier 2, enhancing its portability, while ensuring its electrical interface connection with the main control system.

[0056] In this embodiment, a tray 6 is provided on one side of the chip carrier 2. One end of the tray 6 can hold the chip carrier 2. A limiting plate 7 is provided on the end of the tray 6 away from the chip carrier 2. The setting direction of the limiting plate 7 is perpendicular to the setting direction of the tray 6. A handle 8 is provided on the side of the limiting plate 7 away from the tray 6.

[0057] In this embodiment, a portion of the tray 6 can be stacked with the chip carrier 2, and the position of this portion corresponds to the center position of the solenoid 3. The other portion of the tray 6 is a horizontal plate, and its length corresponds to the distance from the center position of the solenoid 3 to the insertion hole.

[0058] In this embodiment, by setting the limiting plate 7 and the support plate 6, the biochip 5 installed on the chip carrier 2 can be in an upward-facing state.

[0059] In this embodiment, a limiting member 9 is provided on the tray 6. The setting direction of the limiting member 9 is perpendicular to the setting direction of the tray 6 and the setting direction of the limiting plate 7. A through groove 10 is provided on the side of the limiting member 9 away from the tray 6. A limiting groove 11 is provided on the limiting plate 7. The limiting groove 11 communicates with the through groove 10. The wall of the insertion hole is provided with a protrusion that matches the through groove 10 and the limiting groove 11. Under the snapping action of the through groove 10 and the protrusion, the tray 6 can make the chip carrier 2 located at the center position of the solenoid 3.

[0060] In this embodiment, the above-mentioned through groove 10, limiting groove 11 and protrusion can prevent the biochip 5 from being deflected during installation and placement in the solenoid 3.

[0061] In this embodiment, a plurality of latches 12 are provided at the end of the support plate 6 away from the limiting plate 7. The plurality of latches 12 are disposed on opposite sides of the chip carrier 2, and the plurality of latches 12 can fix the chip carrier 2. The latches 12 on opposite sides can further tighten the chip carrier 2.

[0062] In this embodiment, the limiting plate 7 is provided with a switch button 13, which can control the fastening state of the buckle 12. Specifically, the arrangement of multiple buckles 12 facilitates the installation or removal of the chip carrier 2 from the tray 6.

[0063] In this embodiment, a pressing member 15 corresponding to the switch button 13 is provided on the side of the tray 6 away from the chip carrier 2. That is, by controlling the switch button 13, the pressing member 15 can be pressed. At this time, the buckle 12 is in the open state, which makes it easy to place the chip carrier 2 on the tray 6 or remove the chip carrier 2 from the tray 6.

[0064] In this embodiment, the detection steps are illustrated by the following example:

[0065] (1) Place the GMR biochip 5 into the sensor system and record the data detected by the sensor system.

[0066] (2) Inject a sheet-like magnetic tag (concentration of 1 mg / mL, volume of 50 μL) into 50 μL of pathogenic bacteria sample solution, and incubate at 37°C for 10 min in a water bath constant temperature incubator. During the incubation period, shake the reaction container every ten minutes to allow the solution to mix thoroughly and react fully to obtain the magnetically captured pathogenic bacteria.

[0067] (3) The pathogenic bacteria captured by magnetic capture are concentrated and enriched by performing magnetic separation for 1 minute using a magnetic separation instrument, then removing the supernatant and injecting 70 μL of PBS buffer. This is repeated twice, and 20 μL of the bioconcentrated sample is retained to obtain the pathogenic bacteria modified with sheet-like magnetic tags.

[0068] (4) Use GMR biochip 5 to capture pathogens modified with magnetic tags, that is: the magnetically separated pathogenic liquid (20 μL of bioconcentrated sample) is injected into the microfluidic of the GMR chip through a small syringe, and an immune reaction is performed at room temperature of 37°C for 10 minutes. Then, it is washed 5 times with PBS buffer, and then air-dried for detection.

[0069] (5) Place the GMR biochip 5 back into the sensor system, record the data detected by the sensor system, and compare it with the data detected in (1) to determine whether there are pathogens in the sample.

[0070] The chip that captured the pathogens was placed into the sensor system, and the data read is shown in the table below. Through design, the sensor system can read the voltage output of the chip at the 0.1μV level.

[0071] Table 1 Data read by the sensor system

[0072]

[0073] As shown in the table above, the sensor system described above has high sensitivity and can effectively solve the problem of pathogenic bacteria signals being buried in background noise.

[0074] The above are merely preferred embodiments of this specification and are not intended to limit this specification. Various modifications and variations can be made to this specification by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this specification should be included within the scope of protection of this specification.

Claims

1. A sensor system based on sheet-like magnetic tags and GMR magnetic biochips, characterized in that, It includes a programmable power supply board, a signal acquisition board, a chip carrier board, solenoids, and a mounting structure; The signal acquisition board and the chip carrier are connected. A biochip is disposed on the chip carrier. The chip carrier is disposed in the channel of the solenoid. The solenoid is disposed in the loading structure. The programmable power supply board can provide power to the solenoid. The biochip can capture pathogens modified with sheet-like magnetic tags. The sheet-like magnetic tags can magnetically mark the pathogens. The signal acquisition board is equipped with a constant current circuit and a signal acquisition circuit. The constant current circuit can provide a constant current to the biochip, and the signal acquisition circuit can acquire and amplify the signal output by the biochip. The constant current circuit includes a first diode, a second diode, and a control resistor R. G and load resistance R L The first diode and the second diode are connected in series in the feedback loop D. A In this context, the range of the input signal is limited by the control resistor R. G The load resistor R L The second diode and the load resistor R are connected in series with the biochip to control the output current of the current source to the biochip. L It is connected in parallel with the biochip to stabilize the current of the biochip; The signal acquisition circuit includes a first-stage operational amplifier, a second-stage operational amplifier, and an AD converter. The input terminal of the first-stage operational amplifier is connected in parallel with the biochip, and the output terminal of the second-stage operational amplifier is connected to the AD converter. The first-stage operational amplifier can differentially amplify the voltage signal across the biochip. The second-stage operational amplifier can buffer and stabilize the voltage signal output by the first-stage operational amplifier and use it as the input signal of the AD converter. The AD converter can convert the received analog voltage signal into a digital signal and output it to the host computer. A tray is provided on one side of the chip carrier, one end of which can hold the chip carrier. A limiting plate is provided on the end of the tray away from the chip carrier. The setting direction of the limiting plate is perpendicular to the setting direction of the tray. A handle is provided on the side of the limiting plate away from the tray. The loading structure has a mounting hole and an insertion hole on one side. The mounting hole contains the solenoid. The hole channel direction of the mounting hole is the same as that of the insertion hole. The sidewall of the insertion hole abuts against the inner wall of the solenoid. The insertion hole can insert the chip carrier board. The tray is provided with a limiting member, the setting direction of which is perpendicular to both the setting direction of the tray and the setting direction of the limiting plate. A through groove is formed on the side of the limiting member away from the tray, and a limiting groove is formed on the limiting plate. The limiting groove communicates with the through groove. The wall of the insertion hole is provided with a protrusion that matches the through groove and the limiting groove. Under the engaging action of the through groove and the protrusion, the tray can position the chip carrier at the center of the solenoid.

2. The sensor system based on sheet-like magnetic tags and GMR magnetic biochips according to claim 1, characterized in that, The constant current circuit can provide a constant current of 1µA to 20µA to the biochip.

3. The sensor system based on sheet-like magnetic tags and GMR magnetic biochips according to claim 1, characterized in that, The chip carrier has multiple electrode pads on one side, which can provide power to the biochip.

4. The sensor system based on sheet-like magnetic tags and GMR magnetic biochips according to claim 1, characterized in that, The tray is provided with multiple buckles at the end away from the limiting plate. The multiple buckles are located on opposite sides of the chip carrier and can fix the chip carrier.

5. The sensor system based on sheet-like magnetic tags and GMR magnetic biochips according to claim 4, characterized in that, The limiting plate is equipped with a switch button, which can control the fastening state of the buckle.

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