Multi-nuclide nuclear magnetic resonance instrument

Abstract

The embodiment of the invention provides a multi-nuclide nuclear magnetic resonance instrument. The multi-nuclide nuclear magnetic resonance instrument comprises a radio frequency transceiver module, a switch control module, a duplexer module, an impedance matching network and a sample sending tube. The radio frequency transceiver module is connected with the switch control module, a first output end of the switch control module is connected with the duplexer module, and a second output end of the switch control module is connected with the impedance matching network. The impedance matching network comprises a resistance-capacitance circuit and a radio frequency coil, and the radio frequency coil is arranged on the outer side of the sample feeding pipe. And the switch control module switches the circuit structure of the impedance matching network based on the radio frequency pulse transmitted by the radio frequency transceiver module, so that the radio frequency coil outputs a radio frequency wave with a target frequency to excite nuclide of a sample in the sample sending tube. According to the multi-nuclide nuclear magnetic resonance instrument, the circuit structure of the impedance matching network is switched, so that the radio frequency coil can stably resonate under different frequencies, stable resonance and impedance matching are realized under a relatively large frequency span, and the signal acquisition efficiency and the signal-to-noise ratio are improved.

Description

Technical Field

[0001] This application relates to the field of nuclear magnetic resonance technology, and in particular to a multi-nucleoside nuclear magnetic resonance instrument. Background Technology

[0002] Low-field nuclear magnetic resonance (NMR) instruments enable multi-component analysis and structural characterization of samples by detecting the resonance signals of different nuclides. For example, in the field of oil exploration, by measuring the resonance signals of hydrogen nuclei in the sample core (… 1 H) and sodium nucleus ( 23 Na) determines the pore structure of the core and the composition of the fluid within it.

[0003] In existing technologies, probes for multi-core NMR measurements mainly include multi-coil independent measurement schemes and dual-resonance notch filter structures. The multi-coil independent measurement scheme uses independent radio frequency coils for different nuclei and achieves multi-core element measurement through mechanical switching. However, mutual coupling interference exists between the multiple coils, leading to increased signal crosstalk and noise. Furthermore, the mechanical coil switching process is time-consuming and prone to introducing errors, affecting measurement continuity.

[0004] The dual-resonant notch filter scheme utilizes a notch filter or band-stop filter to achieve multi-frequency resonance on a single coil. However, the notch filter structure has a limited matching bandwidth, making it difficult to achieve stable resonance and impedance matching over a large frequency span, resulting in low signal acquisition efficiency and a decrease in signal-to-noise ratio. Summary of the Invention

[0005] This application provides a multi-nucleoside nuclear magnetic resonance instrument. Existing nuclear magnetic resonance instruments have difficulty achieving stable resonance and impedance matching over a large frequency span, resulting in low signal acquisition efficiency and reduced signal-to-noise ratio.

[0006] In a first aspect, the multi-nucleoside nuclear magnetic resonance instrument provided in the embodiments of this application includes:

[0007] RF transceiver module, switch control module, duplexer module, impedance matching network, and sample delivery tube;

[0008] The radio frequency transceiver module is connected to the switch control module, the first output terminal of the switch control module is connected to the duplexer module, and the second output terminal of the switch control module is connected to the impedance matching network.

[0009] The impedance matching network includes a resistor-capacitor circuit and a radio frequency coil. The radio frequency coil is disposed outside the sample tube and is used to emit radio frequency waves when the impedance matching network resonates to excite the nuclides in the sample inside the sample tube.

[0010] The switch control module is used to switch the circuit structure of the impedance matching network based on the radio frequency pulses transmitted by the radio frequency transceiver module, so that the radio frequency coil outputs a radio frequency wave at a target frequency, which is used to excite the nuclides in the sample in the sample delivery tube.

[0011] In one possible implementation, the resistor-capacitor circuit includes: a series resistor, a series capacitor branch, and a parallel capacitor branch;

[0012] The series resistor, the radio frequency coil, and the series capacitor branch are connected in series to form the main series circuit;

[0013] The first end of the parallel capacitor branch is connected to the first end of the series main circuit, and the second end of the parallel capacitor branch is connected to the second end of the series main circuit.

[0014] In one possible implementation, the series capacitor branch includes a plurality of series capacitors and at least one first switch;

[0015] The plurality of series capacitors include a first series capacitor and at least one second series capacitor, wherein the branch of the second series capacitor connected in series with the first switch is connected in parallel with the first series capacitor.

[0016] In one possible implementation, the parallel capacitor branch includes a plurality of parallel capacitors and at least one second switch;

[0017] The plurality of parallel capacitors include a first parallel capacitor and at least one second parallel capacitor, wherein the branch of the second parallel capacitor connected in series with the second switch is connected in parallel to both sides of the first parallel capacitor;

[0018] The first switch and the second switch are arranged in pairs. When one pair of first switches and the second switch are closed at the same time, the other pairs of first switches and the second switches are opened.

[0019] In one possible implementation, the switch control module is used to control the first switch and the second switch, which are arranged in pairs, to open or close simultaneously.

[0020] When both the at least one first switch and the at least one second switch are open, the impedance matching network is in a first working circuit, and when the first working circuit resonates, the radio frequency coil emits a radio frequency wave of a first frequency.

[0021] When the first and second switches are closed simultaneously, the impedance matching network is in the second working circuit. When the second working circuit resonates, the radio frequency coil emits radio frequency waves of the second frequency.

[0022] The first frequency radio frequency wave is used to excite the first nuclide in the sample, and the second frequency radio frequency wave is used to excite the second nuclide in the sample.

[0023] In one possible implementation, the duplexer module includes a high-frequency duplexer and a low-frequency duplexer, both of which are connected to the switch control module.

[0024] The radio frequency transceiver module includes a radio frequency transmitter and a radio frequency receiver;

[0025] The switch control module is used to control the connection of the high-frequency duplexer to the radio frequency transmitter, or to the radio frequency receiver; and,

[0026] The switch control module is used to control the connection of the low-frequency duplexer to the radio frequency transmitter, or to the radio frequency receiver.

[0027] In one possible implementation, the switch control module includes a pulse voltage source and a controller;

[0028] The controller is connected to the pulse voltage source and is used to control the pulse voltage source to generate and output a switching control signal;

[0029] The positive terminal of the pulse voltage source is connected to the first terminal of the switch, the negative terminal of the pulse voltage source is grounded, the second terminal of the switch is grounded, and the switch includes a first switch and a second switch.

[0030] In one possible implementation, a cavity exists between the sample delivery tube and the radio frequency coil, and a Faraday cage is disposed in the cavity;

[0031] A constant-temperature permanent magnet is provided on the outside of the radio frequency coil, and there is a cavity between the radio frequency coil and the constant-temperature permanent magnet.

[0032] In one possible implementation, the Faraday cage is a conductive metal sheet with a cylindrical or polygonal enclosure structure that is slit along the axial direction, used to suppress electromagnetic field drift caused by samples with high dielectric constants.

[0033] In one possible implementation, the switch includes at least one of: a P-intrinsic-N PIN diode switch, a gallium nitride (GaN) RF switch, and a complementary metal-oxide-semiconductor (CMOS) RF switch.

[0034] This application provides a multi-nucleoside nuclear magnetic resonance (NMR) instrument, comprising a radio frequency (RF) transceiver module, a switch control module, a duplexer module, an impedance matching network, and a sample delivery tube. The RF transceiver module is connected to the switch control module; its first output is connected to the duplexer module, and its second output is connected to the impedance matching network. The impedance matching network includes a resistor-capacitor circuit and an RF coil, which is positioned outside the sample delivery tube and emits RF waves when the impedance matching network resonates, exciting the nuclides in the sample within the tube. The switch control module switches the circuit structure of the impedance matching network based on the RF pulses transmitted by the RF transceiver module, causing the RF coil to output RF waves at a target frequency, which is used to excite the nuclides in the sample within the sample delivery tube.

[0035] This multi-nucleoside nuclear magnetic resonance instrument achieves stable resonance of the radio frequency coil at different frequencies by switching the circuit structure of the impedance matching network. As a result, it achieves stable resonance and impedance matching over a large frequency span, improving signal acquisition efficiency and signal-to-noise ratio. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0037] Figure 1 This is a schematic diagram of the structure of a multi-nucleoside nuclear magnetic resonance instrument provided in an embodiment of this application;

[0038] Figure 2 A pulse timing diagram of a multi-nucleoside nuclear magnetic resonance instrument during operation, provided in an embodiment of this application;

[0039] Figure 3 A schematic diagram of an impedance matching network for a multi-nucleoside nuclear magnetic resonance instrument provided in an embodiment of this application;

[0040] Figure 4 This is a schematic diagram of the impedance matching network corresponding to a hydrogen nucleus operating mode provided in an embodiment of this application;

[0041] Figure 5 This application provides a schematic diagram of the impedance matching network corresponding to a sodium core working module.

[0042] Figure 6 A schematic flowchart illustrating a method for constructing an impedance matching network for a multi-nucleoside nuclear magnetic resonance instrument, as provided in an embodiment of this application.

[0043] Figure 7 A schematic diagram of the simulated impedance matching results of the sodium-hydrogen dual-core nuclear magnetic resonance probe provided in the embodiment of this application in sodium core working mode;

[0044] Figure 8 A schematic diagram of the simulation impedance matching results of the sodium-hydrogen dual-nuclear nuclear magnetic resonance probe provided in the embodiment of this application in the hydrogen nucleus working mode;

[0045] Figure 9 A schematic diagram of the structure of the electronic device provided in this application.

[0046] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0047] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0048] First, let me explain the terms used in this application:

[0049] Nuclear magnetic resonance (NMR) is a physical phenomenon based on the behavior of atomic nuclei in a magnetic field. When an atomic nucleus is placed in an external magnetic field, its spin splits into energy levels. By applying radio frequency pulses of a specific frequency, the atomic nucleus can transition between different energy levels, thereby generating a detectable signal.

[0050] Low-field nuclear magnetic resonance (NMR) instrument: refers to an instrument with a magnetic field strength of less than 1T (Tesla).

[0051] Low-field nuclear magnetic resonance (NMR) instruments are widely used in materials science, biomedicine, petroleum exploration, geological exploration, and chemical analysis. Their core function is to perform multi-component analysis and structural characterization of samples by detecting the resonance signals of different nuclides. For example, in petroleum exploration, by measuring the resonance signals of hydrogen nuclei in the sample core (… 1 H) and sodium nucleus ( 23 Na) determines the pore structure of the core and the composition of the fluid within it.

[0052] However, 1 H and 23 The Larmor frequencies of Na differ significantly, for example, under a 0.5T magnetic field. 1 The H resonant frequency is 21.29 MHz (megahertz). 23 Na is 5.3MHz, with a frequency span of 1:4.

[0053] In existing technologies, probes for multi-core NMR measurements mainly include multi-coil independent measurement schemes and dual-resonance notch filter structures. The multi-coil independent measurement scheme uses independent radio frequency coils for different nuclei and achieves multi-core element measurement through mechanical switching. However, mutual coupling interference exists between the multiple coils, leading to increased signal crosstalk and noise. Furthermore, the mechanical coil switching process is time-consuming and prone to introducing errors, affecting measurement continuity.

[0054] Dual-resonance notch filter schemes utilize notch filters or band-stop filters to achieve multi-frequency resonance on a single coil. For example, by designing a notch circuit to isolate non-target frequency signals, the coil can maintain resonance at different core frequencies. However, the matching bandwidth of the notch filter structure is limited, making it difficult to achieve stable resonance and impedance matching over a large frequency span, resulting in low signal acquisition efficiency and a decreased signal-to-noise ratio.

[0055] The multi-nucleoside nuclear magnetic resonance instrument provided in this application includes an impedance matching network and a switch control module. The impedance matching network includes a radio frequency coil. The impedance matching network is connected to the switch control module, which is used to control the switching circuit structure of the impedance matching network. That is, the cross-frequency division time measurement of multiple nuclides is realized through the topology reconstruction of the impedance matching network, which solves the problem that the existing technology is difficult to achieve stable resonance and impedance matching over a large frequency span, resulting in low signal acquisition efficiency and reduced signal-to-noise ratio.

[0056] This application is applicable to multi-nuclear measurement scenarios in low-field nuclear magnetic resonance instruments, specifically including pore structure analysis in materials science, electrolyte concentration monitoring in biomedicine, and reservoir fluid saturation detection in oil exploration. For example, in oil exploration, it is necessary to simultaneously analyze water in the reservoir (…). 1 H) and salt solution ( 23 The distribution characteristics of Na are important for biomedical applications, which require the detection of tissue water and electrolyte concentrations.

[0057] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0058] Figure 1 This is a schematic diagram of the structure of a multi-nucleoside nuclear magnetic resonance instrument provided in an embodiment of this application, as shown below. Figure 1 As shown, the multi-nucleoside nuclear magnetic resonance instrument includes: a radio frequency transceiver module 101, a switch control module 102, a duplexer module 103, an impedance matching network 104, and a sample delivery tube 105.

[0059] The radio frequency transceiver module 101 is connected to the switch control module 102, the first output terminal of the switch control module 102 is connected to the duplexer module 103, and the second output terminal of the switch control module 102 is connected to the impedance matching network 104.

[0060] Impedance matching network 104 includes a resistor-capacitor circuit and an RF coil 106. The RF coil 106 is disposed outside the sample delivery tube and is used to emit RF waves when the impedance matching network 104 resonates, thereby exciting the nuclides in the sample inside the sample delivery tube 105. The RF coil 106 can be, for example, a solenoid structure.

[0061] The switch control module 102 is used to switch the circuit structure of the impedance matching network 104 based on the radio frequency pulses transmitted by the radio frequency transceiver module 101, so that the radio frequency coil outputs a radio frequency wave at the target frequency, which is used to excite the nuclides in the sample tube.

[0062] This multi-nuclide NMR instrument employs a "single radio frequency coil + reconfigurable circuit impedance matching network" to avoid electromagnetic mutual coupling interference between multiple coils, thereby improving the integrated stability of the multi-nuclide NMR instrument. Furthermore, this multi-nuclide NMR instrument can be adapted to the target frequency excitation of various nuclides without changing the probe or coil, improving the operational efficiency and convenience of the multi-nuclide NMR instrument.

[0063] The radio frequency transceiver module 101 is used to generate radio frequency pulses that excite various nuclides and to receive the FID (Free Induction Decay) signal generated by the nuclides during the relaxation process.

[0064] The radio frequency transceiver module 101 establishes a bidirectional communication connection with the data processing end. For example, data interaction and command transmission can be achieved using Ethernet TCP / IP (Transmission Control Protocol / Internet Protocol). The data processing end, for example, can be a computer, used to send configuration parameters for radio frequency pulses to the radio frequency transceiver module 101 and receive the raw echo signal data sent by the radio frequency transceiver module 101, thereby processing multiple raw echo signal data to generate an echo sequence.

[0065] It should be noted that the configuration parameters of the radio frequency pulse are based on the Larmor frequency, relaxation characteristics, and other settings of the nuclide to be excited. These configuration parameters include, but are not limited to, center frequency, pulse bandwidth, pulse shape, acquisition window duration, and the combination method of the pulse sequence.

[0066] The center frequency is equal to the Larmor frequency of the nuclide to be excited in the isothermal magnetic field, and the pulse width is determined based on the excitation characteristics of the nuclide to be excited. For example, a 90° pulse of 10 to 20 μs (microseconds) is used for excitation. 1 H, using a 90° pulse excitation of 20 to 30 μs. 23 The pulse repetition duration can be adjusted from 10 ms (milliseconds) to 10 s (seconds) with a step size of 1 ms. This controls the time interval between two adjacent excitation pulses, balancing measurement efficiency and signal relaxation recovery. The acquisition window duration is determined based on the relaxation duration of the nuclide. This secondary window duration can be adjusted from 1 ms to 500 ms with a step size of 0.1 ms, ensuring complete acquisition of the attenuation process of the echo signal. The pulse sequence can be combined in a way that is, for example, "excitation pulse of the first nuclide + acquisition duration + excitation pulse of the second nuclide + acquisition duration," where the excitation pulses of the first and second nuclides are emitted alternately to excite multiple nuclides in a time-division manner and acquire the echo signals of multiple nuclides.

[0067] Understandably, after receiving the radio frequency pulse transmitted by the radio frequency transceiver module 101, the switch control module 102 generates at least two switch timing signals based on the radio frequency pulse, and the period of the switch timing signals is the same as that of the radio frequency pulse signals.

[0068] For example, the switch control module 102 generates a first switch timing signal based on the transmission period corresponding to the radio frequency pulse and the acquisition window duration, and transmits it to the duplexer module 103 through the first output terminal to control the connection and disconnection between the duplexer module and the radio frequency transmitter and receiver. Furthermore, the switch control module 102 generates a second switch timing signal based on the type of nuclide excited by different pulse periods of the radio frequency pulse and the pulse period. This second switch timing signal is used to control the topology reconstruction of the impedance matching network 104, enabling the impedance matching network 104 to form a stable resonant circuit at the target frequency of the radio frequency pulse, ensuring efficient coupling of radio frequency energy to the radio frequency coil to excite the corresponding nuclide.

[0069] That is, the embodiments of this application provide an impedance matching network with a reconfigurable circuit structure, which enables a single RF coil to adapt to resonance conditions at different frequencies, thereby solving the problem that the prior art is unable to achieve stable resonance and impedance matching over a large frequency span.

[0070] Optionally, when there are multiple switches in the duplexer module 103, the switch control module 102 outputs multiple first switch timing signals, with each switch corresponding to one first switch timing signal. When there are multiple switches in the impedance matching network 104, the switch control module 102 outputs multiple second switch timing signals, with each switch corresponding to one second switch timing signal.

[0071] Figure 2 This is a pulse timing diagram illustrating the operation of a multi-nucleoside nuclear magnetic resonance instrument, provided as an embodiment of this application. (See diagram below.) Figure 2 As shown, S1 is the first switch, and S2 is the second switch. When S1 and S2 are both open, the impedance matching network is in hydrogen nucleus operating mode. When S1 and S2 are both closed, the impedance matching network is in sodium nucleus operating mode. t1 to t2 is one pulse cycle, and t1 to t3 is 1.5 pulse cycles.

[0072] For example, when the pulse signal corresponding to the t1 to t2 period of the radio frequency pulse is a 90° excitation pulse with a frequency of 21.29MHz and a width of 15μs, the second switching timing signal has a 3.3V TTL (Transistor-Transistor Logic) high level during the t1 to t2 period. This is used to control multiple switches in the impedance matching network to open simultaneously, changing the circuit structure of the impedance matching network. When the excitation pulse during the t1 to t2 period is connected to the impedance matching network, the resonant frequency of the impedance matching network 104 is 21.29MHz, meaning that the radio frequency coil 106 emits a 21.29MHz radio frequency wave to excite the hydrogen nuclei of the sample in the sample delivery tube 105. The TTL high level can also be 5V; this application does not limit this.

[0073] During the time interval t1 to t2, S1 and S2 are disconnected, the high-frequency duplexer is turned on, the high-frequency duplexer switches to duplexer transmission state, the excitation pulse is connected to the impedance matching network, the radio frequency coil emits a 21.29MHz radio frequency wave, which excites the hydrogen nuclei in the sample tube.

[0074] During the time interval t2 to t3, S1 and S2 are closed, the low-frequency duplexer is turned on, and the low-frequency duplexer switches to the duplexer receiving state to receive the echo signal generated during the relaxation of hydrogen nuclei in the sample tube.

[0075] Optionally, the impedance matching network described above can be, for example, a π-type matching network. This application does not limit the specific structure of the impedance matching network.

[0076] The multi-nucleoside NMR instrument provided in this application includes a radio frequency transceiver module, a switch control module, a duplexer module, an impedance matching network, and a sample delivery tube. The radio frequency transceiver module is connected to the switch control module; the first output terminal of the switch control module is connected to the duplexer module, and the second output terminal of the switch control module is connected to the impedance matching network. The impedance matching network includes a radio frequency coil disposed outside the sample delivery tube. This coil emits radio frequency waves when the impedance matching network resonates, exciting the nuclides in the sample within the sample delivery tube. The switch control module switches the circuit structure of the impedance matching network based on the radio frequency pulses transmitted by the radio frequency transceiver module, causing the radio frequency coil to output radio frequency waves at a target frequency. This target frequency is used to excite the nuclides in the sample within the sample delivery tube.

[0077] This multi-nucleoside nuclear magnetic resonance instrument achieves stable resonance of the radio frequency coil at different frequencies by switching the circuit structure of the impedance matching network. As a result, it achieves stable resonance and impedance matching over a large frequency span, improving signal acquisition efficiency and signal-to-noise ratio.

[0078] refer to Figure 1 There is a cavity between the sample tube 105 and the radio frequency coil 106, and a Faraday cage 108 is provided in the cavity. The Faraday cage 108 is a conductive metal sheet with a cylindrical or polygonal enclosure structure with slits along the axial direction.

[0079] A thermostatic permanent magnet 107 is provided on the outside of the radio frequency coil 106. There is a cavity between the radio frequency coil 106 and the thermostatic permanent magnet 107. The thermostatic permanent magnet 107 is cylindrical.

[0080] Specifically, the Faraday cage 108 is arranged axially along the RF coil 106, located between the RF coil 106 and the sample delivery tube 105, and is electrically isolated from the RF coil 106. The Faraday cage 108 is made of a highly conductive metal material, such as copper or copper-plated metal sheets, and its structure is a cylindrical or polygonal enclosure with axial slots, used to suppress electromagnetic field drift caused by samples with high dielectric constants.

[0081] Understandably, when an RF coil is working, it generates an alternating electromagnetic field around it, which is the RF magnetic field. When the sample is a substance with a high dielectric constant, such as an electrolyte solution or a high-concentration aqueous solution, the sample will change the original uniform distribution of the RF electric field, causing electric field distortion. This distortion will cause the equivalent capacitance or inductance of the impedance matching network to shift unexpectedly, thus leading to resonant frequency drift.

[0082] The Faraday cage is made of copper or copper-plated metal with high conductivity. Under the action of the distorted radio frequency electric field, it induces a reverse compensation electric field. This reverse compensation electric field cancels out the distorted electric field, so that the electric field in the interaction area between the radio frequency coil and the sample is restored to a uniform distribution, and the electric field interference caused by the dielectric properties of the sample is eliminated.

[0083] In addition, the axial slit cuts off the circumferential closed conductor ring structure of the Faraday cage, preventing it from forming a shielding effect on the axial radio frequency magnetic field. This ensures that the axial radio frequency magnetic field generated by the radio frequency coil can penetrate the cage without obstruction and reach the sample area, thus guaranteeing the efficient coupling of radio frequency energy to the nuclide.

[0084] The isothermal permanent magnet, for example, can be a neodymium iron boron permanent magnet, used to provide a stable 0.5T background magnetic field. In a 0.5T background magnetic field, the resonance frequency of the hydrogen nucleus is 21.29MHz, and that of the sodium nucleus is 5.3MHz.

[0085] Understandably, in the uniform magnetic field of 0.5T provided by the isothermal permanent magnet, the temperature fluctuation is controlled within ±0.1℃, ensuring the long-term stability of the resonance frequencies of the hydrogen and sodium nuclei, and avoiding the mismatch of the resonant bandwidth with the impedance matching network caused by magnetic field drift.

[0086] Specifically, this multi-nucleoside nuclear magnetic resonance instrument effectively suppresses electric field coupling and mode drift under single-coil multi-frequency switching conditions by introducing a Faraday cage structure between the RF coil 106 and the sample tube 105. This allows the RF coil to maintain stable resonant frequency and impedance characteristics in both hydrogen and sodium nucleus operating modes, especially... 1 H and 23 When the ratio of the two Na nuclides to their operating frequencies is greater than 1:3, mode perturbations caused by parasitic parameters during multi-frequency switching are significantly reduced. Furthermore, the isothermal permanent magnet provides a stable background magnetic field, avoiding the problem of mismatch between the nuclide resonant frequency and the resonant bandwidth of the impedance matching network caused by magnetic field drift.

[0087] Figure 3 A schematic diagram of the impedance matching network of a multi-nucleoside nuclear magnetic resonance instrument provided in this application embodiment is shown below. Figure 3 As shown, the impedance matching network includes: a series resistor 301, an RF coil 106, a series capacitor branch 302, and a parallel capacitor branch 303.

[0088] The series resistor 301, the radio frequency coil 106, and the series capacitor branch 302 are connected in series to form a series main circuit. The first end of the parallel capacitor branch 303 is connected to the first end of the series main circuit, and the second end of the parallel capacitor branch 303 is connected to the second end of the series main circuit.

[0089] The series capacitor branch 302 includes multiple series capacitors and at least one first switch. The multiple series capacitors include a first series capacitor and at least one second series capacitor. The branch after the second series capacitor is connected in series with the first switch is connected in parallel with the first series capacitor.

[0090] The parallel capacitor branch 303 includes multiple parallel capacitors and at least one second switch. The multiple parallel capacitors include a first parallel capacitor and at least one second parallel capacitor. The branch formed by the second parallel capacitor and the second switch connected in series is connected in parallel to both sides of the first parallel capacitor.

[0091] It should be noted that the first and second switches are set in pairs. When one pair of first and second switches is closed at the same time, the other pairs of first and second switches are opened.

[0092] The switch control module is used to control the first and second switches, which are set in pairs, to open or close simultaneously.

[0093] When at least one first switch and at least one second switch are both open, the impedance matching network is in a first operating circuit. When the first operating circuit resonates, the RF coil emits an RF wave of a first frequency. When the first pair of first switches and the second switch are simultaneously closed, the impedance matching network is in a second operating circuit. When the second operating circuit resonates, the RF coil emits an RF wave of a second frequency. The RF wave of the first frequency is used to excite a first nuclide in the sample, and the RF wave of the second frequency is used to excite a second nuclide in the sample. The aforementioned first pair of first switches and second switches are used to indicate any one of multiple pairs of first switches and second switches.

[0094] For example, such as Figure 3 As shown, the series capacitor branch 302 includes a first series capacitor 311, a second series capacitor 312, and a first switch 313 connected in series with the second series capacitor 312. The parallel capacitor branch 302 includes a first parallel capacitor 321, a second parallel capacitor 322, and a second switch 323 connected in series with the second parallel capacitor 322.

[0095] When the first switch 313 and the second switch 323 are simultaneously open, the impedance matching network 104 is in the first working circuit for exciting hydrogen nuclei. When the RF transceiver module 101 transmits the RF pulse for exciting hydrogen nuclei to the impedance matching network 104, the impedance matching network 104 resonates, and the RF coil 106 emits a 21.29MHz RF wave to excite the hydrogen nuclei in the sample tube 105.

[0096] Figure 4 This is a schematic diagram of an impedance matching network corresponding to a hydrogen nucleus operating mode provided in an embodiment of this application. The impedance matching network includes a series resistor 301, a radio frequency coil 106, a first series capacitor 311, and a first parallel capacitor 321.

[0097] Furthermore, when the first switch 313 and the second switch 323 are closed simultaneously, the impedance matching network 104 is in the second operating circuit for exciting the sodium nucleus. When the RF transceiver module 101 transmits the RF pulse for exciting the sodium nucleus to the impedance matching network 104, the impedance matching network 104 resonates, and the RF coil 106 emits a 5.3MHz RF wave to excite the sodium nucleus in the sample tube 105.

[0098] Figure 5 This is a schematic diagram of the impedance matching network corresponding to a sodium core working module provided in an embodiment of this application. The impedance matching network includes a series resistor 301, a radio frequency coil 106, a first series capacitor 311, a second series capacitor 312, a first parallel capacitor 321, a second parallel capacitor 322, a first switch 313, and a second switch 323.

[0099] Wherein, the first series capacitor 311 and the second series capacitor 312 are equivalent to the series capacitors of the impedance matching network corresponding to the sodium core working module, and the first parallel capacitor 321 and the second parallel capacitor 322 are equivalent to the parallel capacitors of the impedance matching network corresponding to the sodium core working module.

[0100] Understandably, Figure 3 The RF transceiver module 101, the switch control module 102, and the duplexer module 103 are all equivalent to module 300. Since the connection relationship and function between the RF transceiver module 101, the switch control module 102, and the duplexer module 103 have been explained in the above embodiments, module 300 will not be described again here.

[0101] Figure 4 The impedance matching network shown can achieve the excitation of hydrogen nuclei. Figure 5 The impedance matching network shown enables sodium nucleus excitation. That is, in this embodiment, a large frequency range of 1:4 can be achieved after circuit switching, and the Q (Quality Factor) value remains stable in each operating mode. Through dual-switch isolation technology, the parasitic effects of the non-operating channel are minimized, allowing the same RF coil to maintain a high Q value in dual-frequency mode, thus improving the sensitivity and signal-to-noise ratio of the multi-nucleoside NMR instrument.

[0102] Figure 3 The impedance matching network shown achieves rapid time-division measurement of sodium and hydrogen nuclei using a single RF coil. Furthermore, by constructing two π-type tuned matching networks corresponding to different nuclei and employing a dual-switch control method for topology reconstruction, the probe of the multi-nucleus NMR instrument can stably achieve resonance and impedance matching at different operating frequencies. In addition, the RF switch uses high-speed electronic components, enabling nuclei switching in microseconds, overcoming the shortcomings of traditional mechanical switching methods such as slow response, easy wear, and low reliability.

[0103] The multi-nuclide NMR instrument provided in this application integrates dual-frequency measurement into a single coil structure, avoiding the mutual coupling interference and space occupation problems common in multi-coil schemes, and improving the system's compactness and measurement stability. Simultaneously, the dual-switch structure ensures that the matching network of the non-working nucleus is in an isolated state, preventing additional load on the current resonant circuit and significantly enhancing the matching reliability and Q-value retention capability in different modes. Furthermore, the multi-nuclide NMR instrument can perform sodium and hydrogen nucleus switching measurements without changing the probe, effectively improving instrument efficiency and experimental continuity. Therefore, this multi-nuclide NMR instrument improves the integration, stability, and efficiency of dual-nucleus measurement.

[0104] In one implementation, the switch control module 102 includes a pulse voltage source and a controller. The controller is connected to the pulse voltage source and is used to control the pulse voltage source to generate and output switch control signals.

[0105] The positive terminal of the pulse voltage source is connected to the first terminal of the switch, the negative terminal of the pulse voltage source is grounded, and the second terminal of the switch is grounded. The switch includes a first switch and a second switch.

[0106] The controller can be a logic unit with processing capabilities, such as a CPU (Central Processing Unit) or an MPGA (Masked Programmable Gate Array), and this application does not limit it in this regard.

[0107] Optionally, the controller and the pulse voltage source are electrically connected via an SPI (Serial Peripheral Interface) communication interface. The controlled objects of the switch control module 102 include multiple switches in the impedance matching network, and at least one switch in the duplexer module 103.

[0108] The controller's control signal output is connected to the pulse voltage source's signal input. The controller sends a switching control pulse sequence to the pulse voltage source via the SPI protocol. This switching control pulse sequence can be, for example, binary encoded, where "1" corresponds to the off level and "0" corresponds to the on level.

[0109] Optionally, the switch control module 102 outputs a TTL voltage or bias current to control the synchronous switching of the first and second switches, thereby realizing the topology reconstruction of the impedance matching network.

[0110] Understandably, the switch and pulse voltage source are connected to a common ground terminal to avoid interference from ground potential differences. Therefore, the pulse voltage source outputs a switch control pulse to the switch, and since the switch is grounded, the switch control pulse is ultimately transmitted to the ground terminal.

[0111] Optionally, the first and second switches mentioned above are at least one of PIN (Positive-Intrinsic-Negative) diode switches, GaN (Gallium Nitride) RF switches, and CMOS (Complementary Metal-Oxide-Semiconductor) RF switches. These various electronic switches possess characteristics such as low conduction loss, small turn-off capacitance, and high isolation, enabling switching to be completed on the order of microseconds. This significantly increases the nucleus mode switching speed compared to traditional mechanical switching methods, thereby improving the measurement efficiency of multi-nucleus NMR instruments.

[0112] Because the turn-off capacitance of the first and second switches is extremely small (<0.5pF (picofarad)), the high-frequency network exhibits high impedance at low frequencies, which does not affect the low-frequency resonance quality.

[0113] The multi-nucleoside NMR instrument provided in this application includes a switch control module comprising a pulse voltage source and a controller. The controller is connected to the pulse voltage source and is used to control the pulse voltage source to generate and output switch control signals. The positive terminal of the pulse voltage source is connected to the first terminal of the switch, the negative terminal of the pulse voltage source is grounded, and the second terminal of the switch is grounded. The switch includes a first switch and a second switch. In this scheme, the pulse voltage source synchronously outputs pulse signals to control the first and second switches, driving the first and second switches to turn on and off simultaneously, ensuring the synchronicity of switch switching. Furthermore, using a pulse voltage source to control switch switching reduces the switch switching time, which is beneficial for improving the detection efficiency of different nuclides.

[0114] Furthermore, this application uses a low-level drive switch to close, and the low-level and common ground design reduces the electromagnetic interference of the switch drive circuit to the radio frequency signal.

[0115] In one implementation, the duplexer module 103 includes a high-frequency duplexer and a low-frequency duplexer, both of which are connected to the switch control module. The radio frequency transceiver module includes a radio frequency transmitter and a radio frequency receiver.

[0116] Specifically, the switch control module 102 controls the connection of the high-frequency duplexer to the RF transmitter or the RF receiver; and the switch control module controls the connection of the low-frequency duplexer to the RF transmitter or the RF receiver. That is, the RF transmitter and the RF receiver establish a selective connection with the duplexer module 103 through the switch control module 102.

[0117] like Figure 2As shown, when the high-frequency duplexer is in transmit mode, it is connected to the RF transmitter; when it is in receive mode, it is connected to the RF receiver. The state switching of the low-frequency duplexer is the same as that of the high-frequency duplexer, and will not be described further here.

[0118] The switch control module 102 determines the radio frequency reception and transmission periods for different nuclides based on the received radio frequency pulses. (Reference) Figure 1 When a multi-nucleoside NMR instrument is used for dual-nucleoside detection, the first nuclide can be, for example, […]. 1 H, the second nuclide could be, for example, 23 Na. Because 1 H and 23 The Larmor frequency difference of Na is relatively large, therefore, high-frequency duplexer adapters... 1 H corresponds to high-frequency signal transmission, low-frequency duplexer adapter 23 Na corresponds to low-frequency signal transmission.

[0119] Optionally, the duplexer module 103 includes a third switch and a fourth switch. The third switch is connected in series with the high-frequency duplexer, and the fourth switch is connected in series with the low-frequency duplexer. (Reference) Figure 1 When the third switch is closed and the fourth switch is open, the high-frequency duplexer is turned on, and the radio frequency pulses emitted by the radio frequency transceiver module 101 are transmitted to the high-frequency duplexer. 1 H-type high-frequency π-type matching network. When the third switch is open and the fourth switch is closed, the low-frequency duplexer is turned on, and the RF pulses emitted by the RF transceiver module 101 are transmitted to the low-frequency duplexer. 23 Na-type low-frequency π-type matching network.

[0120] Understandably, the switch control module 102 has two independent switching control units built in, corresponding to the high-frequency duplexer and the low-frequency duplexer respectively. Each duplexer can independently control the on / off state with the RF transmitter and RF receiver. At any given time, only one duplexer is allowed to be in the "transmit / receive switching" state, while the other duplexer is in the high-impedance isolation state.

[0121] The multi-nucleoside NMR instrument provided in this application embodiment achieves isolation between the transmission and reception of different nuclide radio frequency signals through a frequency division design of "high-frequency duplexer + low-frequency duplexer" and precise switching of the connection between the high-frequency duplexer, low-frequency duplexer, and radio frequency transmitter and receiver via a switch control module. Specifically, the receiver is isolated during the radio frequency pulse transmission phase to prevent high-power transmission signals from damaging the receiver link components, and the transmitter is isolated during the echo signal reception phase to prevent transmission link noise from interfering with echo signal acquisition, thereby ensuring signal integrity during both transmission and reception.

[0122] Figure 6This is a flowchart illustrating a method for constructing an impedance matching network for a multi-nucleoside nuclear magnetic resonance (NMR) instrument, as provided in an embodiment of this application. The impedance matching network includes: a first series capacitor, a second series capacitor, a first parallel capacitor, a second parallel capacitor, a first switch, a second switch, a series resistor, and a radio frequency (RF) coil. The second series capacitor is connected in series with the first switch, and the second parallel capacitor is connected in series with the second switch. This method is applied to instruments such as… Figure 1-4 The multi-nucleoside nuclear magnetic resonance instrument is shown. The execution entity of this method can be, for example, an electronic device with corresponding data storage and computing capabilities, such as a computer, server, or server cluster. The electronic device stores and runs a program corresponding to the impedance matching network construction method, and the impedance matching network is constructed by executing this program. The impedance matching network construction method includes:

[0123] S601, Obtain multiple network parameters.

[0124] The network parameters include: the first excitation frequency, the second excitation frequency, the inductance value of the RF coil, the first resistance value of the series resistor, and the impedance to be matched by the impedance matching network.

[0125] In this embodiment, the multi-nucleoside nuclear magnetic resonance instrument is used to excite two nuclides. Therefore, the first excitation frequency is the Larmor frequency of the first nuclide in the static magnetic field provided by the isothermal permanent magnet, and the second excitation frequency is the Larmor frequency of the second nuclide in the static magnetic field provided by the isothermal permanent magnet. The first nuclide can be, for example, a hydrogen nucleus, and the second nuclide can be, for example, a sodium nucleus. In a static magnetic field of 0.5T, the first excitation frequency for exciting the hydrogen nucleus is 21.29MHz, and the second excitation frequency for exciting the sodium nucleus is 5.3MHz.

[0126] The inductance of the RF coil can be, for example, 2 to 3 μH (microhenry). The RF coil does not change with the core type; impedance matching is achieved entirely through switching the impedance matching network.

[0127] The impedance to be matched is the standard system impedance of the low-field NMR instrument, which can be, for example, 50 Ω (ohms).

[0128] It should be noted that the first resistance value is an adjustable parameter. In an impedance matching network, the series resistor is used to control circuit losses and ensure circuit stability. Specifically, the series resistor moderately dissipates the energy generated during circuit oscillation, controlling the Q value of the impedance matching network at resonance within a reasonable range, thus avoiding excessively high Q values ​​that lead to narrow resonant bandwidth and signal distortion.

[0129] S602. Check whether multiple network parameters meet the feasibility test conditions. If multiple network parameters meet the feasibility test conditions, proceed to step S603. If multiple network parameters do not meet the feasibility test conditions, proceed to step S607.

[0130] Among them, the feasibility test conditions include whether the first relationship formed by the first resistance value and the matching network impedance is less than or equal to 0.

[0131] Alternatively, the first relation can be, for example: .in, The impedance to be matched, This is the first resistance value of the series resistor.

[0132] S603. Based on the first resistance value and the impedance to be matched, determine the reactance of the matching network.

[0133] The matching network reactance is the equivalent reactance of the series main circuit at the target frequency. It is used to cancel the inductive reactance of the RF coil, enabling the series main circuit to achieve series resonance and laying the foundation for subsequent impedance matching. The matching network reactance is determined based on the following formula:

[0134]

[0135] in, The impedance to be matched, This is the first resistance value of the series resistor.

[0136] S604. Based on multiple network parameters, a first mapping relationship, a second mapping relationship, and the connection relationship between multiple capacitors, determine the capacitance values ​​of the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor.

[0137] The connection relationship between the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor is referenced. Figure 2 .

[0138] Specifically, the connection relationships between the capacitors are analyzed, and the capacitance value of each capacitor is calculated by combining the above-mentioned network parameters.

[0139] Optionally, a method for calculating the capacitance value of each capacitor is provided herein. This method includes: determining the first parallel capacitance value of the first parallel capacitor based on a first mapping relationship between the matching network reactance, a first resistance value, a first excitation frequency, and the parallel capacitors; determining the first series capacitance value of the first series capacitor based on a second mapping relationship between the matching network reactance, inductance value, a second excitation frequency, and the series capacitors; determining the total value of the parallel capacitors based on the first mapping relationship between the matching network reactance, the first resistance value, the second excitation frequency, and the first mapping relationship; determining the total value of the series capacitors based on the second mapping relationship between the matching network reactance, inductance value, the second excitation frequency, and the series capacitors; and determining the capacitance values ​​of the second series capacitor and the second parallel capacitor based on the circuit connection relationship between the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor, as well as the first parallel capacitor value, the first series capacitor value, the total value of the parallel capacitors, and the total value of the series capacitors.

[0140] For example, the first mapping relationship can be:

[0141]

[0142] in, This is the value of the parallel capacitor. The matching network reactance determined in step S603 above, The excitation frequency of the nuclide to be excited. This is the first resistance value of the series resistor.

[0143] The first excitation frequency corresponding to the hydrogen nucleus is 21.29 MHz, reference... Figure 2 Substituting the first excitation frequency, the known first resistance value, and the matching network reactance into the aforementioned first mapping relationship, the first parallel capacitance value of the first parallel capacitor 211 is obtained. .

[0144] For example, the second mapping relationship can be:

[0145]

[0146] in, This is the value of the series capacitor. The matching network reactance determined in step S603 above, The excitation frequency of the nuclide to be excited. This represents the inductance value of the RF coil.

[0147] The first excitation frequency corresponding to the hydrogen nucleus is 21.29 MHz, reference... Figure 2 Substituting the first excitation frequency, the known inductance value, and the matching network reactance into the second mapping relationship described above, the first series capacitance value of the first series capacitor is obtained. .

[0148] Thus, based on the first and second mapping relationships, the impedance matching network corresponding to the hydrogen nucleus's working mode has been determined; that is, the impedance matching network has been determined. Figure 3 The impedance matching network corresponding to the hydrogen nucleus operating mode shown is illustrated.

[0149] Furthermore, in sodium core operating mode, both the first and second switches are turned on, reference... Figure 2 The first series capacitor and the second series capacitor are equivalent to the series capacitor of the impedance matching network, and the first parallel capacitor and the second parallel capacitor are equivalent to the parallel capacitor of the impedance matching network.

[0150] Therefore, the second excitation frequency corresponding to the sodium nucleus is 5.3MHz, and the reactance of the aforementioned matching network is... And, the first resistance value Substituting into the first mapping relationship above, we obtain the total value of the parallel capacitors. The second excitation frequency is 5.3MHz, and the reactance of the matching network is as described above. And, inductance value Substituting into the second mapping relationship above, we obtain the total value of the series capacitance. .

[0151] refer to Figure 2 The total series capacitance is obtained by equivalent calculation of the first and second series capacitors connected in parallel. .exist and Given the information, based on this formula, we can obtain... , This is the capacitance value of the second series capacitor.

[0152] Furthermore, the total parallel capacitance is calculated by equivalent parallel calculation of the first and second parallel capacitors. .exist and Given the information, based on this formula, we can obtain... , This is the capacitance value of the second parallel capacitor.

[0153] S605. Determine whether each capacitor value is greater than 0; if each capacitor value is greater than 0, proceed to step S606; if at least one capacitor value is less than or equal to 0, proceed to step S607.

[0154] The above step S604 yields Figure 2 The capacitance values ​​of the four capacitors are determined. If each capacitance value is greater than 0, then step S606 is executed to output the capacitance values.

[0155] If at least one capacitance value is less than or equal to 0, it means that the calculation result is not feasible. Execute the following step S607 to adjust the first total value and recalculate the capacitance value of each capacitor.

[0156] S606 outputs the capacitance values ​​of the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor.

[0157] S607, Adjust the first resistance value.

[0158] If the impedance to be matched and the first resistance value satisfy the first relationship in step S602 above, it means that the first resistance value is too large, and the first resistance value needs to be reduced.

[0159] Optionally, an upper and lower limit value for the first resistance can be set to limit the adjustable range of the series resistor, ensuring the engineering feasibility, performance stability, and efficiency of the adjustment process. The upper limit value of the first resistance is determined based on the first relationship shown in step S602 above, and the lower limit value is determined based on hardware constraints and Q-value constraints. For example, the upper limit value of the first resistance can be 12Ω, and the lower limit value of the first resistance can be, for example, 8Ω.

[0160] It should be noted that if the judgment result of step S605 indicates that at least one capacitance value is less than or equal to 0, the first resistance value is reduced, and step S602 is re-executed to perform a feasibility test.

[0161] Specifically, the quality factor of the resonant circuit .in, The resonant frequency, First resistance value, This represents the inductance value of the RF coil. A Q value that is too high leads to narrow bandwidth and easy mismatch, while a Q value that is too low leads to high circuit losses and poor sensitivity. This method establishes a trade-off between matching feasibility constraints and the quality factor of the resonant circuit, enabling the dual-core RF matching network to achieve positive capacitance solution, stable matching, and high signal sensitivity in different core operating modes.

[0162] Figure 7 This is a schematic diagram illustrating the simulated impedance matching results of the sodium-hydrogen dual-core nuclear magnetic resonance probe in sodium core operating mode, as provided in an embodiment of this application. Figure 8 This is a schematic diagram illustrating the simulated impedance matching results of the sodium-hydrogen dual-nuclear nuclear magnetic resonance probe provided in the embodiments of this application in hydrogen nucleus operating mode. Figure 7 and Figure 8 As shown, the horizontal axis represents the frequency output by the RF coil, and the vertical axis represents the reflection coefficient S11. The reflection coefficient S11 measures the degree of RF signal reflection; a smaller value indicates a better impedance matching effect from the impedance matching network. In the S11 simulation curve, the frequency corresponding to the lowest point is the resonant frequency of the impedance matching network.

[0163] Figure 7 The S11 simulation curve corresponding to the sodium nucleus is shown below. Figure 7 As shown, the lowest point of the S11 curve corresponds to a frequency of 5.3 MHz, which is consistent with the Larmor frequency of the sodium nucleus, thus satisfying the excitation condition of the sodium nucleus. Figure 8 The S11 simulation curve corresponding to the hydrogen nucleus, such as Figure 8 As shown, the lowest point of the S11 curve corresponds to a frequency of 21.29 MHz, which is consistent with the Larmor frequency of the hydrogen nucleus, thus satisfying the excitation conditions of the hydrogen nucleus.

[0164] In hydrogen nucleus mode, the resonant point is at 21.29MHz, and the lowest S11 can reach -25dB. In sodium nucleus mode, the resonant point is at 5.3MHz, and the lowest S11 can reach -15dB. The two curves do not interfere with each other, indicating that the impedance matching network provided in this application has good impedance matching characteristics in both frequency modes.

[0165] The impedance matching network construction method for a multi-nuclear nuclear magnetic resonance instrument provided in this application involves acquiring multiple network parameters and detecting whether these parameters meet feasibility testing conditions. If all network parameters meet the feasibility testing conditions, the matching network reactance is determined based on a first resistance value and the impedance to be matched. Then, based on the multiple network parameters, a first mapping relationship, a second mapping relationship, and the connection relationships between multiple capacitors, the capacitance values ​​of the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor are determined. After obtaining the capacitance values ​​of all capacitors, it is determined whether each capacitance value is greater than 0. If all capacitance values ​​are greater than 0, the capacitance values ​​of the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor are output. Furthermore, if at least one capacitance value is less than or equal to 0, the first resistance value is adjusted until all obtained capacitance values ​​are greater than 0. If the network parameters do not meet the feasibility testing conditions, the first resistance value is adjusted until all network parameters meet the feasibility testing conditions.

[0166] This method, based on a mathematical model and combined with the circuit connection method of the impedance matching network, accurately derives the capacitance value of each capacitor, achieving standardization of capacitance value calculation and facilitating the acquisition of a more reliable impedance matching network that meets the requirements.

[0167] Furthermore, this method, based on feasibility detection conditions and capacitance value judgment conditions, avoids the problem of physical impossibility caused by mathematical calculations, ensuring the feasibility of the determined capacitance. Further, this method combines the frequency of the element to be excited to calculate the capacitance values ​​of multiple capacitors in the impedance matching network for different scenarios, ensuring that the impedance matching network can adapt to the required detection scenarios. For example, the impedance matching network calculated by combining the excitation frequencies of sodium and hydrogen nuclei accurately adapts to the impedance matching requirements of a large frequency span of 1:4, thereby helping to provide stable resonance for dual-core measurements.

[0168] Figure 9 A schematic diagram of the structure of the electronic device provided in this application. Figure 9 As shown, the electronic device 90 provided in this embodiment includes at least one processor 901 and a memory 902. Optionally, the device 90 further includes a communication component 903. The processor 901, memory 902, and communication component 903 are connected via a bus 904.

[0169] In the specific implementation process, at least one processor 901 executes computer execution instructions stored in memory 902, causing at least one processor 901 to execute the impedance matching network construction method of the above-mentioned multi-nucleoside nuclear magnetic resonance instrument.

[0170] The specific implementation process of processor 901 can be found in the above embodiment of the impedance matching network construction method for multi-nucleoside nuclear magnetic resonance instruments. The implementation principle and technical effect are similar, and will not be repeated here.

[0171] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0172] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0173] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0174] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method for constructing an impedance matching network for a multi-nucleoside nuclear magnetic resonance instrument.

[0175] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method for constructing an impedance matching network for a multi-nucleoside nuclear magnetic resonance instrument.

[0176] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0177] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0178] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0179] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0180] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0181] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0182] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0183] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0184] Other embodiments of this application will readily conceive of by considering the specification and practicing the disclosure herein. This application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The specification and embodiments are to be considered exemplary only, and the scope of this application is limited only by the appended claims.

Claims

1. A multi-nuclide nuclear magnetic resonance instrument, characterized in that, include: RF transceiver module, switch control module, duplexer module, impedance matching network, and sample delivery tube; The radio frequency transceiver module is connected to the switch control module, the first output terminal of the switch control module is connected to the duplexer module, and the second output terminal of the switch control module is connected to the impedance matching network. The impedance matching network includes a resistor-capacitor circuit and a radio frequency coil. The radio frequency coil is disposed outside the sample tube and is used to emit radio frequency waves when the impedance matching network resonates to excite the nuclides in the sample inside the sample tube. The switch control module is used to switch the circuit structure of the impedance matching network based on the radio frequency pulses transmitted by the radio frequency transceiver module, so that the radio frequency coil outputs a radio frequency wave at a target frequency, which is used to excite the nuclides in the sample in the sample delivery tube.

2. The multi-nucleoside nuclear magnetic resonance instrument according to claim 1, characterized in that, The resistor-capacitor circuit includes: a series resistor, a series capacitor branch, and a parallel capacitor branch; The series resistor, the radio frequency coil, and the series capacitor branch are connected in series to form the main series circuit; The first end of the parallel capacitor branch is connected to the first end of the series main circuit, and the second end of the parallel capacitor branch is connected to the second end of the series main circuit.

3. The multi-nucleoside nuclear magnetic resonance instrument according to claim 2, characterized in that, The series capacitor branch includes multiple series capacitors and at least one first switch; The plurality of series capacitors include a first series capacitor and at least one second series capacitor, wherein the branch of the second series capacitor connected in series with the first switch is connected in parallel with the first series capacitor.

4. The multi-nucleoside nuclear magnetic resonance instrument according to claim 3, characterized in that, The parallel capacitor branch includes multiple parallel capacitors and at least one second switch; The plurality of parallel capacitors include a first parallel capacitor and at least one second parallel capacitor, wherein the branch of the second parallel capacitor connected in series with the second switch is connected in parallel to both sides of the first parallel capacitor; The first switch and the second switch are arranged in pairs. When one pair of first switches and the second switch are closed at the same time, the other pairs of first switches and the second switches are opened.

5. The multi-nucleoside nuclear magnetic resonance instrument according to claim 4, characterized in that, The switch control module is used to control the first switch and the second switch, which are set in pairs, to open or close simultaneously. When both the at least one first switch and the at least one second switch are open, the impedance matching network is in a first working circuit, and when the first working circuit resonates, the radio frequency coil emits a radio frequency wave of a first frequency. When the first and second switches are closed simultaneously, the impedance matching network is in the second working circuit. When the second working circuit resonates, the radio frequency coil emits radio frequency waves of the second frequency. The first frequency radio frequency wave is used to excite the first nuclide in the sample, and the second frequency radio frequency wave is used to excite the second nuclide in the sample.

6. The multi-nucleoside nuclear magnetic resonance instrument according to any one of claims 1-5, characterized in that, The duplexer module includes a high-frequency duplexer and a low-frequency duplexer, both of which are connected to the switch control module. The radio frequency transceiver module includes a radio frequency transmitter and a radio frequency receiver; The switch control module is used to control the connection of the high-frequency duplexer to the radio frequency transmitter, or to the radio frequency receiver; and, The switch control module is used to control the connection of the low-frequency duplexer to the radio frequency transmitter, or to the radio frequency receiver.

7. The multi-nucleoside nuclear magnetic resonance instrument according to claim 6, characterized in that, The switch control module includes a pulse voltage source and a controller; The controller is connected to the pulse voltage source and is used to control the pulse voltage source to generate and output a switching control signal; The positive terminal of the pulse voltage source is connected to the first terminal of the switch, the negative terminal of the pulse voltage source is grounded, the second terminal of the switch is grounded, and the switch includes a first switch and a second switch.

8. The multi-nucleoside nuclear magnetic resonance instrument according to claim 1, characterized in that, There is a cavity between the sample delivery tube and the radio frequency coil, and a Faraday cage is provided in the cavity; A constant-temperature permanent magnet is provided on the outside of the radio frequency coil, and there is a cavity between the radio frequency coil and the constant-temperature permanent magnet.

9. The multi-nucleoside nuclear magnetic resonance instrument according to claim 8, characterized in that, The Faraday cage is a conductive metal sheet with a cylindrical or polygonal enclosure structure that has slits along the axial direction, used to suppress electromagnetic field drift caused by samples with high dielectric constants.

10. The multi-nucleoside nuclear magnetic resonance instrument according to claim 7, characterized in that, The switch includes at least one of: a P-intrinsic-NPIN diode switch, a gallium nitride (GaN) RF switch, and a complementary metal-oxide-semiconductor (CMOS) RF switch.

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