A nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function

Abstract

The invention discloses a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function, comprising a magnetic shielding shell, an internal device and an external device, wherein the internal device comprises a main magnet, a resonant circuit, a radio frequency coil, a coil fixing rod, a test tube slot, a straight key self-locking switch, a magnetic stripe support frame, a travel switch and a Hall sensor probe, wherein 16 magnetic stripe slots are arranged on the magnetic stripe support frame, the main magnet comprises 16 permanent magnets, the radio frequency coil, the travel switch and the Hall sensor probe are respectively mounted on the coil fixing rod, and the external device comprises a radio frequency pulse modulation circuit and an embedded microprocessor; the advantage is that the central magnetic field strength of the main magnet can be measured to calibrate the frequency of the radio frequency pulse, so that the frequency of the radio frequency pulse is matched with the central uniform magnetic field, and the adverse effect of the permanent magnet temperature characteristics on the matching of the central magnetic field strength and the radio frequency pulse frequency is eliminated, thereby improving the detection accuracy of the nuclear magnetic resonance.

Description

Technical Field

[0001] The invention relates to a nuclear magnetic resonance sensor system, in particular to a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function. Background Art

[0002] Nuclear magnetic resonance technology is a detection technology used in medical imaging, oil well exploration, material testing, food safety and other fields. It has the characteristics of high detection accuracy, non-destructive samples, and fast detection speed. This technology uses the interaction between atomic magnetism and external magnetic fields to place the object to be tested in a constant uniform magnetic field (i.e., external magnetic field). Due to the effect of the external magnetic field, the atomic nuclei (such as hydrogen protons) in the object to be tested form a certain angle with the external magnetic field, producing a gyroscope-like motion form, precessing around the direction of the external magnetic field, and the precession frequency satisfies ω=γB 0 Larmor formula, where ω is the angular frequency, γ is the magnetic gyrometry ratio, and B 0 is the magnetic field strength of the uniform magnetic field. At this time, the components of the magnetic moment in the X-axis and Y-axis directions will cancel each other, while the components of the magnetic moment in the Z-axis direction will be superimposed to form a longitudinal magnetization vector, which cannot be directly measured by the RF coil. Then an RF pulse is applied perpendicular to the uniform magnetic field, and the RF pulse generates an RF magnetic field B 1 , the energy transmitted by the RF pulse causes the protons in the low-energy state to transition to the high-energy state. At the same time, the RF pulse pushes the protons to the synchronous state and spins together, forming transverse magnetization, which can be detected by the RF coil. After the RF pulse is removed, the RF coil can be used to detect the T2 relaxation time of the proton synchronization state and the T1 relaxation time of the high-energy protons falling back to the low-energy state. Different substances have different "T1" and "T2" relaxation characteristics for detection. Therefore, the magnetic field strength B of the uniform magnetic field 0 Frequency matching with radio frequency pulses plays a vital role in nuclear magnetic resonance detection.

[0003] like Figure 1As shown, the nuclear magnetic resonance detector is generally composed of a sensor system and a signal transmission and acquisition analysis system, wherein the sensor system is composed of a main magnet, a radio frequency coil and a matching resonant circuit. In the current low-cost small portable nuclear magnetic resonance detector sensor system, its main magnet is composed of a permanent magnet, so that a uniform magnetic field is generated at its center. Reference 1 (Xu Xiaoyu. Research on Dynamic Characteristics and Temperature Field of Halbach-type Magnetic Gears [D]. Jiangsu University, 2019.) clearly discloses that the magnetism of permanent magnet materials will decrease when the temperature rises, and demagnetization may occur at high temperatures. It can be seen that the permanent magnet itself has temperature characteristics, is easily affected by the external temperature, and has poor stability. However, the detection environment of the small portable nuclear magnetic resonance detector is uncertain, such as the harsh environment of high temperature in oil well exploration. In these detection environments, the main magnet is affected by temperature, and the central uniform magnetic field generated by it is also affected by temperature. The change of uniform magnetic field directly affects the frequency matching of radio frequency pulses. Once the uniform magnetic field and radio frequency pulses do not match, the magnetization of protons in the detected material under the originally set frequency pulse will be reduced, or even no magnetization will be generated, thus affecting the detection accuracy.

[0004] Reference 2 (Zhang Yajie. Nuclear magnetic resonance method and sensor design for online monitoring of power oil degradation status [D]. Chongqing University, 2016.) proposed a structural design of a portable sensor system. The nuclear magnetic resonance sensor system is mainly composed of two rectangular permanent magnet blocks, a special shape of shim iron sheet, a ferromagnetic base, a radio frequency coil and a matching and tuning circuit. The permanent magnet is mainly used to generate a uniform magnetic field. The special shape of the shim iron sheet is used to enhance the uniformity of the uniform magnetic field. The ferromagnetic base can make the magnetic lines under the permanent magnet form a loop to reduce leakage magnetic field, thereby strengthening the magnetic field strength of the uniform magnetic field. The radio frequency coil is used to send radio frequency signals, and the matching and tuning circuit is used to complete tuning, filtering and other functions. In order to improve the signal-to-noise ratio of the detection, the two rectangular permanent magnet blocks use neodymium iron boron materials with larger residual magnetism. However, it is still unable to solve the influence of the permanent magnet's own temperature characteristics on the central uniform magnetic field it generates. Therefore, the central uniform magnetic field generated by the nuclear magnetic resonance sensor system at different temperatures is different, which leads to the mismatch between the set frequency of the RF pulse and its central uniform magnetic field, resulting in the weakening of the magnetization phenomenon during the detection process, which in turn affects the detection accuracy. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function. The nuclear magnetic resonance sensor system can measure the central magnetic field strength of the main magnet to calibrate the frequency of the radio frequency pulse, so that the frequency of the radio frequency pulse matches the central uniform magnetic field, eliminating the adverse effects of the temperature characteristics of the permanent magnet on the matching of the central magnetic field strength and the radio frequency pulse frequency, thereby improving the detection accuracy of the nuclear magnetic resonance.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function, comprising a magnetic shielding shell, an internal device and an external device, wherein the internal device comprises a main magnet, a resonant circuit, a radio frequency coil, a coil fixing rod, a test tube slot, a straight key self-locking switch, a magnetic stripe support frame, a travel switch and a Hall sensor probe, wherein the resonant circuit is installed inside the magnetic shielding shell, the resonant circuit is connected to the radio frequency coil, the magnetic stripe support frame is fixed at the inner center of the magnetic shielding shell, the magnetic stripe support frame has a first cavity inside, 16 magnetic stripe slots are arranged on the magnetic stripe support frame, and the 16 magnetic stripe slots surround the first cavity to form a Halbach structure, the main magnet comprises 16 permanent magnets, the 16 permanent magnets are inserted into the 16 magnetic stripe slots one by one, the 16 permanent magnets generate a uniform magnetic field inside the magnetic stripe support frame, and a closed environment is formed inside the magnetic shielding shell for shielding the interference of the earth's magnetic field to enhance the uniformity of the uniform magnetic field;The test tube slot is used to place the detection solution. The coil fixing rod is provided with a second cavity for inserting the test tube slot. The second cavity is through-connected from top to bottom. The coil fixing rod includes a first round rod, a second round rod and a third round rod connected in sequence from top to bottom. The first round rod, the second round rod and the third round rod are coaxial. The second cavity extends from the top center of the first round rod to the bottom center of the third round rod. The radio frequency coil is wound around the second round rod and is located in the middle of the coil fixing rod. The top of the first round rod is provided with a first groove communicating with the second cavity. The side wall of the second round rod is provided with a second groove communicating with the second cavity. The travel switch is installed at the first groove. When the test tube slot is not inserted into the second cavity, the travel switch extends into the second cavity and is in an untriggered state. When the test tube slot is inserted into the second cavity, the test tube slot will contact the travel switch during the downward movement of the test tube slot. At this time, the travel switch will be squeezed by the test tube slot and leave the second cavity, and the travel switch is triggered. The Hall sensor probe is installed at the second groove. The Hall sensor probe is in a vertical state with the side wall of the second cavity. When the test tube slot is not inserted into the second cavity, the Hall sensor probe is in an initial state. State, in the initial state, the Hall sensor probe extends to the center of the second cavity, and detects the magnetic field strength of the uniform magnetic field in real time. When the test tube slot is inserted into the second cavity, the test tube slot will contact the Hall sensor probe during the downward movement of the test tube slot. At this time, the Hall sensor probe will be squeezed by the test tube slot and leave the second cavity. The straight key self-locking switch is installed at the lower part of the second cavity. When the test tube slot is inserted from the top of the second cavity to the test position, the straight key self-locking switch is compressed to the locked position and locked. When the test is completed, the test tube slot is pressed downward, and the lock of the direct key self-locking switch will be released. At this time, the direct key self-locking switch The external device includes a radio frequency pulse modulation circuit and an embedded microprocessor; the radio frequency pulse modulation circuit is connected to the resonant circuit and the embedded microprocessor respectively, and the embedded microprocessor is connected to the travel switch and the Hall sensor probe respectively; when the nuclear magnetic resonance sensor system is in a non-detection state, that is, the test tube slot is not inserted into the second cavity, the travel switch is in an untriggered state, the Hall sensor probe detects the magnetic field strength of the uniform magnetic field in real time and generates a corresponding magnetic field strength signal in real time and sends it to the embedded microprocessor, and the embedded microprocessor converts the received magnetic field strength signal into a magnetic field strength value in real time;When the test tube slot is loaded with the detection solution and inserted into the second cavity, in the process of the test tube slot entering the second cavity, first, the side wall of the test tube slot will squeeze the travel switch, so that the travel switch is triggered, and the travel switch sends a trigger corresponding signal to the embedded microprocessor. At this time, the embedded microprocessor receives the trigger corresponding signal sent by the travel switch, no longer receives the magnetic field strength signal sent by the Hall sensor probe, and uses the magnetic field strength value obtained by the current last conversion to match the frequency of the corresponding radio frequency pulse, and then the embedded microprocessor controls the radio frequency pulse modulation circuit to generate a radio frequency signal of the frequency and send it to the resonant circuit. The resonant circuit tunes and filters the pulse signal to obtain a tuned pulse signal and sends it to the radio frequency coil. As the test tube slot is inserted, the side wall of the test tube slot will squeeze the Hall sensor probe, pressing the Hall sensor probe into the second groove. As the test tube slot goes deeper, the bottom of the test tube slot contacts the straight key self-locking switch, and the test tube slot is Continue to insert and compress the straight key self-locking switch until the straight key self-locking switch shrinks and self-locks in the set position. At this time, the detection solution in the test tube slot is also in the center of the uniform magnetic field, and the test tube slot completely enters the second cavity. At this time, the insertion of the test tube slot is completed, and then the detection solution can be tested. After the test is completed, the test tube slot needs to be taken out, and the test tube slot is pressed downward with a finger. At the same time, the straight key self-locking switch is released from self-locking. After the finger is released, the straight key self-locking switch rebounds, and the straight key self-locking switch pushes the test tube slot out, so that the top of the test tube slot is exposed to the second cavity, and the top of the test tube slot is grasped to pull out the entire test tube slot. During the process of pulling out the test tube slot, the Hall sensor probe is no longer squeezed and restored to the initial position. After the test tube slot is completely pulled out, the travel switch is released and is in an untriggered state. The embedded microprocessor detects the signal that the travel switch is released, controls the radio frequency pulse modulation circuit to stop the generation of the radio frequency signal, and restarts to receive the magnetic field strength signal detected by the Hall sensor probe. ;

[0007] The magnetic shielding shell is composed of a magnetic shielding shell upper cover, a magnetic shielding shell main shell, and a magnetic shielding shell bottom cover. The first cavity is arranged on the magnetic shielding shell main shell and is connected from top to bottom. The magnetic shielding shell upper cover is detachably mounted on the top of the magnetic shielding shell main shell, and the magnetic shielding shell bottom cover is detachably mounted on the bottom of the magnetic shielding shell main shell. The magnetic shielding shell upper cover is provided with a test tube slot insertion port for inserting the test tube slot into the second cavity. The resonant circuit is placed in the gap between the magnetic shielding shell upper cover and the magnetic strip support frame. The resonant circuit is connected to the radio frequency pulse modulation circuit through a signal connector, and the signal connector extends from the magnetic shielding shell upper cover to the outside of the magnetic shielding shell.

[0008] Compared with the prior art, the advantage of the present invention is that a nuclear magnetic resonance sensor system is formed by a magnetic shielding shell, an internal device and an external device, the internal device includes a main magnet, a resonant circuit, a radio frequency coil, a coil fixing rod, a test tube slot, a straight key self-locking switch, a magnetic stripe support frame, a travel switch and a Hall sensor probe, the resonant circuit is installed inside the magnetic shielding shell, the resonant circuit and the radio frequency coil are connected, the magnetic stripe support frame is fixed at the inner center of the magnetic shielding shell, the interior of the magnetic stripe support frame has a first cavity, 16 magnetic stripe slots are arranged on the magnetic stripe support frame, the 16 magnetic stripe slots surround the first cavity to form a Halbach structure, the main magnet includes 16 permanent magnets, and the 16 permanent magnets are inserted into the 16 magnetic stripe slots one by one. , 16 permanent magnets generate a uniform magnetic field inside the magnetic strip support frame, and a closed environment is formed inside the magnetic shielding shell to shield the interference of the earth's magnetic field to enhance the uniformity of the uniform magnetic field; the test tube slot is used to place the detection solution, and a second cavity for inserting the test tube slot is provided on the coil fixing rod, and the second cavity is connected from top to bottom. The coil fixing rod includes a first round rod, a second round rod and a third round rod connected in sequence from top to bottom. The first round rod, the second round rod and the third round rod are coaxial, and the second cavity extends from the center of the top of the first round rod to the center of the bottom of the third round rod. The radio frequency coil is wound around the second round rod and is located in the middle of the coil fixing rod. The top of the first round rod is provided with a first groove connected to the second cavity, and the side wall of the second round rod is provided with a first groove connected to the second cavity. A second groove connected to the second cavity is provided, and a travel switch is installed at the first groove. When the test tube groove is not inserted into the second cavity, the travel switch extends into the second cavity, and the travel switch is in an untriggered state. When the test tube groove is inserted into the second cavity, the test tube groove will contact the travel switch during the downward movement of the test tube groove. At this time, the travel switch will be squeezed by the test tube groove and leave the second cavity, and the travel switch is triggered. The Hall sensor probe is installed at the second groove, and the Hall sensor probe is in a vertical state with the side wall of the second cavity. When the test tube groove is not inserted into the second cavity, the Hall sensor probe is in an initial state. In the initial state, the Hall sensor probe extends to the center of the second cavity to detect the magnetic field strength of the uniform magnetic field in real time. When the test tube slot is inserted into the second cavity, the test tube slot will contact the Hall sensor probe during the downward movement of the test tube slot. At this time, the Hall sensor probe will be squeezed by the test tube slot and leave the second cavity. The direct key self-locking switch is installed at the lower part of the second cavity. When the test tube slot is inserted from the top of the second cavity to the test position, the direct key self-locking switch is compressed to the locking position and locked. When the test is completed, the test tube slot is pressed downward, and the lock of the direct key self-locking switch will be released. At this time, the direct key self-locking switch is reset to push the test tube slot out; the external device includes a radio frequency pulse modulation circuit and an embedded microprocessor; the radio frequency pulse modulation circuit is respectively connected to the resonant circuit and the embedded microprocessor, and the embedded microprocessor is respectively connected to the travel switch and the Hall sensor probe;When the nuclear magnetic resonance sensor system is in a non-detection state, that is, the test tube slot is not inserted into the second cavity, the travel switch is in an untriggered state, and the Hall sensor probe detects the magnetic field strength of the uniform magnetic field in real time and generates a corresponding magnetic field strength signal in real time and sends it to the embedded microprocessor, and the embedded microprocessor converts the received magnetic field strength signal into a magnetic field strength value in real time; when the test tube slot is loaded with the detection solution and inserted into the second cavity, in the process of the test tube slot entering the second cavity, the side wall of the test tube slot will first squeeze the travel switch, so that the travel switch is triggered, and the travel switch sends a trigger corresponding signal to the embedded microprocessor, and the embedded microprocessor The processor receives the trigger response signal sent by the travel switch and no longer receives the magnetic field strength signal sent by the Hall sensor probe. It uses the magnetic field strength value obtained by the current last conversion to match the frequency of the corresponding RF pulse. Then the embedded microprocessor controls the RF pulse modulation circuit to generate an RF signal of this frequency and sends it to the resonant circuit. The resonant circuit tunes and filters the pulse signal to obtain a tuned pulse signal and sends it to the RF coil. As the test tube slot is inserted, the side wall of the test tube slot will squeeze the Hall sensor probe and press the Hall sensor probe into the second groove. As the test tube slot goes deeper, the bottom of the test tube slot contacts the straight key self-locking switch. , continue to insert the test tube slot into the compressed straight key self-locking switch until the straight key self-locking switch shrinks and self-locks in the set position. At this time, the test solution in the test tube slot is also in the center of the uniform magnetic field, and the test tube slot is completely in the second cavity. At this time, the insertion of the test tube slot is completed, and then the test solution can be tested. After the test is completed, the test tube slot needs to be taken out, and the test tube slot is pressed down with a finger. At the same time, the straight key self-locking switch is released from the self-locking. After the finger is released, the straight key self-locking switch rebounds, and the straight key self-locking switch pushes the test tube slot out, so that the top of the test tube slot is exposed to the second cavity, and the top of the test tube slot is grabbed to pull out the entire test tube slot. During the process of pulling out the test tube slot, Hall The sensor probe is no longer squeezed and returns to the initial position. After the test tube slot is completely pulled out, the travel switch is released and in an untriggered state. The embedded microprocessor detects the signal of the travel switch being released, controls the radio frequency pulse modulation circuit to stop the generation of the radio frequency signal, and restarts to receive the magnetic field strength signal detected by the Hall sensor probe, and repeats the process. Thus, the present invention can measure the central magnetic field strength of the main magnet to calibrate the frequency of the radio frequency pulse, so that the frequency of the radio frequency pulse matches the central uniform magnetic field, eliminates the adverse effects of the permanent magnet temperature characteristics on the matching of the central magnetic field strength and the radio frequency pulse frequency, and thus improves the detection accuracy of nuclear magnetic resonance. ; BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is the general block diagram of the nuclear magnetic resonance detector;

[0010] Figure 2 It is a general block diagram of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention;

[0011] Figure 3 A three-dimensional diagram of the internal device of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention;

[0012] Figure 4 for Figure 3 The cross-sectional view of the internal device of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention is taken along AA;

[0013] Figure 5 A schematic diagram of a magnetic shielding shell of a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function according to the present invention;

[0014] Figure 6 It is a schematic diagram of a magnetic strip support frame of a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function of the present invention;

[0015] Figure 7 A schematic diagram of a coil fixing rod of a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function according to the present invention;

[0016] Figure 8 A schematic diagram of a test tube slot of a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function according to the present invention;

[0017] Fig. 9 A schematic diagram of the Halbach magnetic array structure of the main magnet of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention;

[0018] Fig.10 This is a simulation diagram of the Halbach magnetic array structure of the main magnet of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below with reference to the accompanying drawings.

[0020] Example: Figures 2 to 8As shown, a nuclear magnetic resonance sensor system with a radio frequency pulse frequency calibration function includes a magnetic shielding shell, an internal device and an external device, the internal device includes a main magnet, a resonant circuit 1, a radio frequency coil 2, a coil fixing rod 3, a test tube slot 4, a straight key self-locking switch 5, a magnetic stripe support frame 6, a travel switch 7 and a Hall sensor probe 8, the resonant circuit 1 is installed inside the magnetic shielding shell, the resonant circuit 1 is connected to the radio frequency coil 2, the magnetic stripe support frame 6 is fixed at the inner center of the magnetic shielding shell, the magnetic stripe support frame 6 has a first cavity 9 inside, 16 magnetic stripe slots 10 are arranged on the magnetic stripe support frame 6, and the 16 magnetic stripe slots 10 surround the first cavity 9 to form a Halbach structure, the main magnet includes 16 permanent magnets, the 16 permanent magnets are inserted into the 16 magnetic stripe slots 10 one by one, the 16 permanent magnets generate a uniform magnetic field inside the magnetic stripe support frame 6, and a closed environment is formed inside the magnetic shielding shell to shield the interference of the earth's magnetic field to enhance the uniformity of the uniform magnetic field generated by the 16 permanent magnets;The test tube slot 4 is used to place the detection solution. The coil fixing rod 3 is provided with a second cavity 11 for inserting the test tube slot 4. The second cavity 11 is connected from top to bottom. The coil fixing rod 3 includes a first round rod 12, a second round rod 13 and a third round rod 14 connected in sequence from top to bottom. The first round rod 12, the second round rod 13 and the third round rod 14 are coaxial. The second cavity 11 extends from the top center of the first round rod 12 to the bottom center of the third round rod 14. The radio frequency coil 2 is wound around the second round rod 13 and is located in the middle of the coil fixing rod 3. The top of the first round rod 12 is provided with a first groove 15 connected to the second cavity 11, and the side wall of the second round rod 13 is provided with a first groove 15 connected to the second cavity 11. There is a second groove 16 connected to the second cavity 11, and the travel switch 7 is installed at the first groove 15. When the test tube slot 4 is not inserted into the second cavity 11, the travel switch 7 extends into the second cavity 11, and the travel switch 7 is in an untriggered state. When the test tube slot 4 is inserted into the second cavity 11, the test tube slot 4 will contact the travel switch 7 during the downward movement of the test tube slot 4. At this time, the travel switch 7 will be squeezed by the test tube slot 4 and leave the second cavity 11, and the travel switch 7 is triggered. The Hall sensor probe 8 is installed at the second groove 16, and the Hall sensor probe 8 is in a vertical state with the side wall of the second cavity 11. When the test tube slot 4 is not inserted into the second cavity 11, the Hall sensor The Hall sensor probe 8 is in an initial state. In the initial state, the Hall sensor probe 8 extends to the center of the second cavity 11 to detect the magnetic field strength of the uniform magnetic field in real time. When the test tube slot 4 is inserted into the second cavity 11, the test tube slot 4 will contact the Hall sensor probe 8 during the downward movement of the test tube slot 4. At this time, the Hall sensor probe 8 will be squeezed by the test tube slot 4 and leave the second cavity 11. The straight key self-locking switch 5 is installed at the lower part of the second cavity 11. When the test tube slot 4 is inserted from the top of the second cavity 11 to the test position, the straight key self-locking switch 5 is compressed to the locked position and locked. When the test is completed, the test tube slot 4 is pressed downward, and the lock of the straight key self-locking switch 5 will be released. When the straight key self-locking switch 5 is reset, the test tube slot 4 is ejected; the external device includes a radio frequency pulse modulation circuit and an embedded microprocessor; the radio frequency pulse modulation circuit is connected to the resonant circuit 1 and the embedded microprocessor respectively, and the embedded microprocessor is connected to the travel switch 7 and the Hall sensor probe 8 respectively; when the nuclear magnetic resonance sensor system is in a non-detection state, that is, the test tube slot 4 is not inserted into the second cavity 11, the travel switch 7 is in an untriggered state, and the Hall sensor probe 8 detects the magnetic field strength of the uniform magnetic field in real time and generates a corresponding magnetic field strength signal in real time and sends it to the embedded microprocessor, and the embedded microprocessor converts the received magnetic field strength signal into a magnetic field strength value in real time;When the test tube slot 4 is loaded with the detection solution and inserted into the second cavity 11, in the process of the test tube slot 4 entering the second cavity 11, the side wall of the test tube slot 4 will first squeeze the travel switch 7, so that the travel switch 7 is triggered, and the travel switch 7 sends a trigger corresponding signal to the embedded microprocessor. At this time, the embedded microprocessor receives the trigger corresponding signal sent by the travel switch 7, and no longer receives the magnetic field strength signal sent by the Hall sensor probe 8, and uses the magnetic field strength value obtained by the current last conversion to match the frequency of the corresponding radio frequency pulse, and then the embedded microprocessor controls the radio frequency pulse modulation circuit to generate a radio frequency signal of this frequency and sends it to the resonant circuit 1. The resonant circuit 1 tunes and filters the pulse signal to obtain a tuned pulse signal and sends it to the radio frequency coil 2. As the test tube slot 4 is inserted, the side wall of the test tube slot 4 will squeeze the Hall sensor probe 8, pressing the Hall sensor probe 8 into the second groove 16. As the test tube slot 4 goes deeper, the bottom of the test tube slot 4 contacts the straight key self-locking switch 5, and the test tube slot 4 continues to Insert and compress the straight key self-locking switch 5 until the straight key self-locking switch 5 shrinks and self-locks in the set position. At this time, the detection solution in the test tube slot 4 is also in the center of the uniform magnetic field. The test tube slot 4 completely enters the second cavity 11. At this time, the insertion of the test tube slot 4 is completed, and then the detection solution can be tested. After the test is completed, the test tube slot 4 needs to be taken out, and the test tube slot 4 is pressed downward with a finger. At the same time, the straight key self-locking switch 5 is unlocked. After the finger is released, the straight key self-locking switch 5 rebounds, and the straight key self-locking switch 5 pushes the test tube slot 4 out, so that the top of the test tube slot 4 is exposed to the second cavity 11. The top of the test tube slot 4 is grasped to pull out the test tube slot 4. During the process of pulling out the test tube slot 4, the Hall sensor probe 8 is no longer squeezed and restored to the initial position. After the test tube slot 4 is completely pulled out, the travel switch 7 is released and is in an untriggered state. The embedded microprocessor detects the signal that the travel switch 7 is released, controls the radio frequency pulse modulation circuit to stop the generation of the radio frequency signal, and restarts to receive the magnetic field strength signal detected by the Hall sensor probe 8. ;

[0021] In this embodiment, the magnetic shielding shell is composed of a magnetic shielding shell upper cover 17, a magnetic shielding shell main shell 18 and a magnetic shielding shell bottom cover 19. The first cavity 9 is arranged on the magnetic shielding shell main shell 18 and penetrates from top to bottom. The magnetic shielding shell upper cover 17 is detachably installed on the top of the magnetic shielding shell main shell 18. The magnetic shielding shell bottom cover 19 is detachably installed on the bottom of the magnetic shielding shell main shell 18. The magnetic shielding shell upper cover 17 is provided with an insertion port of a test tube slot 4 for inserting the test tube slot 4 into the second cavity 11. The resonant circuit 1 is placed in the gap between the magnetic shielding shell upper cover 17 and the magnetic strip support frame 6. The resonant circuit 1 is connected to the radio frequency pulse modulation circuit through a signal connector 20. The signal connector 20 extends from the magnetic shielding shell upper cover 17 to the outside of the magnetic shielding shell.

[0022] The Halbach magnetic array structure schematic diagram of the main magnet of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention is as follows Fig. 9 As shown, analysis Fig. 9 It can be seen that the unit magnets in the Halbach array have the same magnetization direction and geometric dimensions. This array magnet can gather magnetic lines of force on the inside of the array and weaken them on the outside. Through ANSYS magnetic field simulation, we get the following: Fig.10 The Halbach magnetic array structure simulation diagram of the main magnet of the nuclear magnetic resonance sensor system with radio frequency pulse frequency calibration function of the present invention is shown, and the analysis Fig.10 It can be seen that the color inside the Halbach magnetic array is consistent, indicating that the magnetic field strength is consistent and evenly distributed within this range. From this, it can be inferred that the array magnet can generate a magnetic field with good uniformity.

Claims

1. A nuclear magnetic resonance sensor with radio frequency pulse frequency calibration function, Features It comprises a magnetic shielding shell, an internal device and an external device, wherein the internal device comprises a main magnet, a resonant circuit, a radio frequency coil, a coil fixing rod, a test tube slot, a straight key self-locking switch, a magnetic stripe support frame, a travel switch and a Hall sensor probe, wherein the resonant circuit is installed inside the magnetic shielding shell, the resonant circuit is connected to the radio frequency coil, the magnetic stripe support frame is fixed at the inner center of the magnetic shielding shell, the inner part of the magnetic stripe support frame has a first cavity, the magnetic stripe support frame is provided with 16 magnetic stripe slots, the 16 magnetic stripe slots surround the first cavity to form a Halbach structure, the main magnet comprises 16 permanent magnets, the 16 permanent magnets are inserted into the 16 magnetic stripe slots one by one, the 16 permanent magnets generate a uniform magnetic field inside the magnetic stripe support frame, and a closed environment is formed inside the magnetic shielding shell for shielding the interference of the earth's magnetic field to enhance the uniformity of the uniform magnetic field;The test tube slot is used to place the detection solution. The coil fixing rod is provided with a second cavity for inserting the test tube slot. The second cavity is connected from top to bottom. The coil fixing rod includes a first round rod, a second round rod and a third round rod connected in sequence from top to bottom. The first round rod, the second round rod and the third round rod are coaxial. The second cavity extends from the center of the top of the first round rod to the center of the bottom of the third round rod. The radio frequency coil is wound around the second round rod and is located in the middle of the coil fixing rod. The top of the first round rod is provided with a cavity connected to the second cavity. The first groove of the second round rod is provided with a second groove connected with the second cavity on the side wall of the second round rod, the travel switch is installed at the first groove, when the test tube slot is not inserted into the second cavity, the travel switch extends into the second cavity, and the travel switch is in an untriggered state, when the test tube slot is inserted into the second cavity, during the downward movement of the test tube slot, the test tube slot will contact the travel switch, and the travel switch will be squeezed by the test tube slot to leave the second cavity, the travel switch is triggered, and the Hall sensor probe is installed At the second groove, the Hall sensor probe is in a vertical state with respect to the side wall of the second cavity. When the test tube slot is not inserted into the second cavity, the Hall sensor probe is in an initial state. In the initial state, the Hall sensor probe extends to the center of the second cavity to detect the magnetic field strength of the uniform magnetic field in real time. When the test tube slot is inserted into the second cavity, the test tube slot will contact the Hall sensor probe during the downward movement of the test tube slot. At this time, the Hall sensor probe will be squeezed by the test tube slot and leave the second cavity. The straight key self-locking switch The switch is installed at the lower part of the second cavity. When the test tube slot is inserted from the top of the second cavity to the test position, the direct key self-locking switch is compressed to the locking position and locked. When the test is completed, the test tube slot is pressed downward, and the lock of the direct key self-locking switch will be released. At this time, the direct key self-locking switch is reset to eject the test tube slot; the external device includes a radio frequency pulse modulation circuit and an embedded microprocessor; the radio frequency pulse modulation circuit is respectively connected to the resonant circuit and the embedded microprocessor, and the embedded microprocessor is respectively connected to the travel switch and the Hall sensor probe; When the nuclear magnetic resonance sensor is in a non-detection state, that is, the test tube slot is not inserted into the second cavity, the travel switch is in an untriggered state, the Hall sensor probe detects the magnetic field strength of the uniform magnetic field in real time and generates a corresponding magnetic field strength signal in real time and sends it to the embedded microprocessor, and the embedded microprocessor converts the received magnetic field strength signal into a magnetic field strength value in real time; when the test tube slot is loaded with the detection solution and inserted into the second cavity, in the process of the test tube slot entering the second cavity, the side wall of the test tube slot first squeezes the travel switch, so that the travel switch is triggered, and the travel switch sends a trigger corresponding signal to the embedded microprocessor. At this time, the embedded microprocessor receives the trigger corresponding signal sent by the travel switch, no longer receives the magnetic field strength signal sent by the Hall sensor probe, and uses the magnetic field strength value obtained by the current last conversion to match the frequency of the corresponding radio frequency pulse, and then the embedded microprocessor controls the radio frequency pulse modulation circuit to generate a radio frequency signal of the frequency and sends it to the resonant circuit, and the resonant circuit tunes and filters the pulse signal to obtain a tuned pulse signal and sends it to the radio frequency coil. As the test tube slot is inserted, the side wall of the test tube slot squeezes the The Hall sensor probe is pressed into the second groove. As the test tube groove goes deeper, the bottom of the test tube groove contacts the straight key self-locking switch. The test tube groove is further inserted to compress the straight key self-locking switch until the straight key self-locking switch shrinks and self-locks in the set position. At this time, the detection solution in the test tube groove is also in the center of the uniform magnetic field. The test tube groove completely enters the second cavity. At this time, the insertion of the test tube groove is completed, and then the detection solution can be tested. After the test is completed, the test tube groove needs to be taken out, and the test tube groove is pressed downward with a finger. At the same time, the straight key self-locking switch is pressed downward with a finger. The lock switch releases self-locking, and the straight key self-locking switch rebounds after the finger is released. The straight key self-locking switch pushes out the test tube slot, so that the second cavity is exposed at the top of the test tube slot, and the top of the test tube slot is grasped to pull out the entire test tube slot. During the process of pulling out the test tube slot, the Hall sensor probe is no longer squeezed and restored to its initial position. After the test tube slot is completely pulled out, the travel switch is released and is in an untriggered state. The embedded microprocessor detects the signal that the travel switch is released, controls the RF pulse modulation circuit to stop generating RF signals, and restarts receiving the magnetic field strength signal detected by the Hall sensor probe.

2. A nuclear magnetic resonance sensor with radio frequency pulse frequency calibration function according to claim 1, Features The magnetic shielding shell is composed of a magnetic shielding shell upper cover, a magnetic shielding shell main shell, and a magnetic shielding shell bottom cover. The first cavity is arranged on the magnetic shielding shell main shell and is connected from top to bottom. The magnetic shielding shell upper cover is detachably mounted on the top of the magnetic shielding shell main shell, and the magnetic shielding shell bottom cover is detachably mounted on the bottom of the magnetic shielding shell main shell. The magnetic shielding shell upper cover is provided with a test tube slot insertion port for inserting the test tube slot into the second cavity. The resonant circuit is placed in the gap between the magnetic shielding shell upper cover and the magnetic strip support frame. The resonant circuit is connected to the radio frequency pulse modulation circuit through a signal connector, and the signal connector extends from the magnetic shielding shell upper cover to the outside of the magnetic shielding shell.

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