Vagus nerve magnetic stimulation system

Abstract

The invention provides a vagus nerve magnetic stimulation system, which comprises an inverter circuit, a rectification circuit, a frequency adjusting circuit and a magnetic stimulation coil which are connected, and is characterized in that the magnetic stimulation coil is arranged at the vagus nerve position of the neck of a user; the inverter circuit is connected with a direct-current stabilized power supply to provide power supply, the inverter circuit is connected through a first control module, and the first control module is configured to drive the inverter circuit through an output control signal; the frequency regulation circuit is connected through a second control module, and the second control module is configured to drive the frequency regulation circuit to be switched on and off through an output control signal so as to regulate the frequency of the magnetic stimulation coil. According to the vagus nerve magnetic stimulation system, the stimulation position, the stimulation intensity and the stimulation frequency can be accurately controlled, and therefore accurate magnetic stimulation on the vagus nerve is achieved.

Description

Technical Field

[0001] This application belongs to the technical field of neuromagnetic stimulation, and particularly relates to a vagus nerve magnetic stimulation system. Background Art

[0002] Epilepsy is a common chronic neurological disease. Approximately one-third of patients are ultimately diagnosed with refractory epilepsy, which seriously affects the quality of life and social function of patients. Conventional anti-epileptic drugs have poor efficacy, and traditional surgical operations also have limitations due to factors such as epileptogenic focus localization, surgical risks, and indication ranges. In recent years, the rapid development of neuromodulation technology has provided new options for the treatment of refractory epilepsy.

[0003] The vagus nerve is one of the most important peripheral nerves in the human body. It is the tenth cranial nerve, originating from the medulla oblongata of the brain and distributed in multiple organs and systems. The vagus nerve is a mixed nerve that transmits both sensory information and controls motor functions, especially in the autonomic nervous system, where it is responsible for regulating many key physiological processes. The main functions of the vagus nerve include controlling heart function, regulating breathing, controlling the digestive system, and regulating the immune system.

[0004] With the development of neuromodulation technology, the research on vagus nerve stimulation (VNS) has gradually become mature. The basic principle of vagus nerve stimulation is to implant a small electrical stimulation device (similar to a cardiac pacemaker) into the neck and wrap the electrode around the vagus nerve trunk in the neck. The electrode acts on the vagus nerve by changing the intensity of the induced electric field, thereby regulating the neural activities of the brain and the body.

[0005] Vagus nerve stimulation has made important progress in the field of epilepsy treatment. By stimulating the vagus nerve with electrodes, it can reduce the frequency and intensity of epileptic seizures and improve the quality of life of patients. However, traditional vagus nerve stimulation is an invasive therapy. Although the curative effect is obvious, it is an invasive operation. Since it requires implanting electrodes around the vagus nerve in the neck, its clinical application is limited. Summary of the Invention

[0006] In view of this, this application aims to propose a vagus nerve magnetic stimulation system, which induces an induced electric field equivalent to the stimulation intensity of vagus nerve electrical stimulation at the target position through an alternating magnetic field, so as to solve the problem that traditional vagus nerve electrical stimulation requires surgical implantation of electrodes.

[0007] To achieve the above object, the technical solution of this application is realized as follows: This application provides a vagus nerve magnetic stimulation system, including an inverter circuit, a rectifier circuit, a frequency adjustment circuit, and a magnetic stimulation coil connected to each other. Among them, the magnetic stimulation coil is arranged at the position of the user's cervical vagus nerve; The inverter circuit is connected to a DC regulated power supply to provide power supply. The inverter circuit is connected through a first control module, and the first control module is configured to drive the inverter circuit through an output control signal; The frequency adjustment is connected through a second control module, and the second control module is configured to drive the frequency adjustment circuit to turn on and off through an output control signal, thereby adjusting the frequency of the magnetic stimulation coil.

[0008] Further, the first control module and the second control module include: A control circuit and a drive circuit connected to the control circuit. Among them, the control circuit includes a control chip, and the control chip is configured to generate a pulse signal with a fixed frequency. The pulse signal is transmitted to the drive circuit through an optocoupler isolation boost circuit, and the drive circuit outputs a drive signal to drive the inverter circuit or the frequency adjustment circuit.

[0009] Further, the rectifier circuit is an LC rectifier circuit composed of an LC filter and a diode. The LC filter is configured to rectify and filter the signal output by the inverter circuit, and the diode is configured to convert an AC signal into a pulsed DC signal.

[0010] Further, the frequency adjustment circuit is composed of a switching tube, a resistor, and a first capacitor to output a pulsed current with an adjustable frequency of 0 - 50 Hz.

[0011] Further, the magnetic stimulation coil has a D-shaped structure, which includes two D-shaped skeletons with different diameters and exciting coils wound on the two D-shaped skeletons. One end of the exciting coil is connected to the frequency adjustment circuit through a second capacitor, and the other end is respectively connected to the frequency adjustment circuit and the rectifier circuit.

[0012] Further, the bottom end face of the magnetic stimulation coil is a stimulation surface and is attached to the position of the user's cervical vagus nerve.

[0013] Further, the inner and outer peripheral edges of the magnetic stimulation coil are both provided with rounded corners.

[0014] Compared with the prior art, the vagus nerve magnetic stimulation system described in this application has the following beneficial effects: A vagus nerve magnetic stimulation system described in the present application utilizes the low-pass characteristics of biological tissues. A low-frequency pulsed current is applied to the magnetic stimulation coil to generate an alternating magnetic field. By adjusting the output power of the DC regulated power supply and the frequency of the frequency adjustment circuit, the intensity and frequency of the stimulation can be precisely controlled, thereby achieving precise magnetic stimulation of the vagus nerve. In addition, the focusing area formed by this device can cover the vagus nerve in the user's neck, and has the characteristics of good focusing, high stimulation intensity and non-invasiveness, meeting the design expectations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings: Figure 1 is a circuit diagram of a vagus nerve magnetic stimulation system according to an embodiment of this application; Figure 2 is a schematic structural diagram of the magnetic stimulation coil according to an embodiment of this application; Figure 3 is a front view of the magnetic stimulation coil according to an embodiment of this application; Figure 4 is a top view of the magnetic stimulation coil according to an embodiment of this application; Figure 5 is a simulation diagram of the focusing area of the magnetic stimulation coil according to an embodiment of this application; Figure 6 is a simulation diagram of the magnetic stimulation coil without chamfering treatment according to an embodiment of this application; Figure 7 is a simulation diagram of the focusing area of the existing figure-eight magnetic stimulation coil according to an embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to make the purpose, technical solutions and advantages of this application clearer, the following further details this application in conjunction with specific embodiments and with reference to the drawings.

[0017] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the ordinary meanings understood by those of ordinary skill in the art to which the present application belongs. The "first", "second" and similar terms used in the embodiments of the present application do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0018] Please refer to Figure 1 As shown, this embodiment provides a vagus nerve magnetic stimulation system, including an inverter circuit, a rectifier circuit, a frequency adjustment circuit and a magnetic stimulation coil connected to each other, wherein the magnetic stimulation coil is arranged at the position of the vagus nerve in the user's neck; The inverter circuit is connected to a DC regulated power supply to provide power supply. The inverter circuit is connected through a first control module, and the first control module is configured to drive the inverter circuit through the output control signal; The frequency adjustment is connected through a second control module, and the second control module is configured to drive the on and off of the frequency adjustment circuit through the output control signal, thereby adjusting the frequency of the magnetic stimulation coil.

[0019] Specifically, in this embodiment, the DC regulated power supply is a regulated power supply with adjustable output power for controlling the stimulation intensity. The inverter circuit adopts a single-phase full-bridge inverter circuit. The single-phase full-bridge inverter circuit is connected to the rectifier circuit. The rectifier circuit is connected to the magnetic stimulation coil through the frequency adjustment circuit, and the magnetic stimulation coil is correspondingly arranged at the position of the vagus nerve in the user's neck.

[0020] The first control module is used to control the single-phase full-bridge inverter circuit to generate a high-frequency sinusoidal stimulation current. After passing through the rectifier circuit, the high-frequency sinusoidal stimulation current becomes a high-frequency sinusoidal half-wave stimulation current with a more regular shape, that is, a pulsed current. After the pulsed current enters the frequency adjustment circuit, the second control module controls the on and off of the frequency adjustment to control the on and off of the pulsed current, so as to achieve the purpose of controlling the frequency of the pulsed current. The pulsed current after frequency adjustment is passed into the magnetic stimulation coil to realize the stimulation of the vagus nerve in the user's neck.

[0021] This application utilizes the low-pass characteristic of biological tissues. A low-frequency pulsed current is applied to the magnetic stimulation coil to generate an alternating magnetic field. By adjusting the output power of the DC regulated power supply and the frequency of the frequency adjustment circuit, the intensity and frequency of the stimulation can be precisely controlled, thereby achieving precise magnetic stimulation of the vagus nerve.

[0022] In some embodiments, the first control module and the second control module include: A control circuit and a drive circuit connected to the control circuit. Among them, the control circuit includes a control chip, and the control chip is configured to generate a pulsed signal with a fixed frequency. The pulsed signal is transmitted to the drive circuit through an opto-isolated boost circuit, and the drive circuit outputs a drive signal to drive an inverter circuit or a frequency adjustment circuit.

[0023] Specifically, in this embodiment, the first control module and the second control module include a connected control circuit and an opto-isolated boost circuit. The control circuit includes a control chip, and the control chip generates a 3.3V pulsed signal with a fixed frequency. The pulsed signal is boosted to 15V through the opto-isolated boost circuit and transmitted to the drive circuit. The drive circuit includes a drive chip, and the drive chip outputs a drive signal for driving a single-phase full-bridge inverter circuit.

[0024] The inverter circuit includes four connected switching tubes. The drive circuit in the first control module controls the opening and closing of each switching tube. The method is to control the two switching tubes on the same bridge arm not to conduct simultaneously, and the two switching tubes at the diagonal corners conduct simultaneously to achieve the inverter function.

[0025] Furthermore, the single-phase full-bridge inverter circuit includes four switching tubes. The drive signal drives the opening and closing of each switching tube. The specific method is as follows: The two switching tubes on the same bridge arm do not conduct simultaneously, and the two switching tubes at the diagonal corners conduct simultaneously. The two groups of switching tubes conduct alternately to initially convert the DC current into an AC current.

[0026] Among them, Q1 and Q4 are the same group of switching tubes; Q2 and Q3 are the same group of switching tubes. When Q1 and Q4 are controlled to conduct, Q2 and Q3 are controlled not to conduct; correspondingly, when Q2 and Q3 are controlled to conduct, Q1 and Q4 are controlled not to conduct. The on and off times of the two groups of switching tubes are kept the same, and the switching tubes on the same bridge arm conduct complementarily. The conduction frequency is set to 1000Hz, and the DC current output by the DC regulated power supply is inverted into a 1000Hz AC current after passing through the single-phase full-bridge inverter circuit.

[0027] In some embodiments, the rectifier circuit is an LC rectifier circuit composed of an LC filter and a diode. The LC filter is configured to rectify and filter the signal output by the inverter circuit, and the diode is configured to convert the AC signal into a pulsed DC signal.

[0028] Specifically, in this embodiment, the rectifier circuit consists of an LC filter and a diode D0 to form an LC rectifier circuit. Among them, the LC filter includes an inductor L0 and a capacitor C0. The inductor L0 is mainly used to filter high-frequency noise, and the capacitor C0 is mainly used to smooth the output voltage and reduce the fluctuations in the DC power supply. The diode D0 functions as a one-way conductor, converting the AC signal into a pulsed DC signal.

[0029] Similar to the first control module, the second control module transmits the control signal to the drive circuit, and the drive circuit outputs a drive signal to drive the conduction and cutoff of the switching tube in the frequency adjustment circuit.

[0030] The 1000Hz alternating current generated by the above single-phase full-bridge inverter circuit is fed into the rectifier circuit. The rectifier circuit consists of an LC filter and a diode D0 to form an LC rectifier circuit. Among them, the LC filter includes an inductor L0 and a capacitor C0. The inductor L0 is mainly used to store energy and filter high-frequency noise, and the function of the capacitor C0 is to smooth the output voltage and reduce fluctuations. The inductor L0 and the capacitor C0 cooperate to improve the quality of the current output. The diode D0 plays a role of one-way conduction during rectification, converting the 1000Hz sinusoidal alternating current into a 1000Hz pulsed current. The pulse width of this pulsed current is 0.5ms, and the pulse amplitude is determined by the output current amplitude of the DC regulated power supply.

[0031] In some embodiments, the frequency adjustment circuit is composed of a switching tube, a resistor, and a first capacitor to output a pulsed current with an adjustable frequency of 0 - 50Hz.

[0032] Specifically, in this embodiment, since biological tissues have a low-pass characteristic, it is necessary to adjust the frequency of the 1000Hz pulsed current. The specific frequency adjustment circuit consists of an IGBT. The second control module is required to achieve frequency adjustment, and the specific frequency adjustment range is 0 - 50Hz. That is, after the 1000Hz pulsed current passes through the frequency adjustment circuit, a pulsed current with an adjustable frequency of 0 - 50Hz is output. Similar to the first control module, the control signal output by the control chip of the second control module is input to the drive chip of the drive circuit, and the drive chip outputs a drive signal to drive the conduction and cutoff of the IGBT.

[0033] After passing through the above single-phase full-bridge inverter circuit, rectifier circuit, and frequency adjustment circuit, the current input to the magnetic stimulation coil is a pulsed current with an adjustable frequency of 0 - 50Hz, and the pulse amplitude of the pulsed current can also be independently adjusted by adjusting the output power of the DC output power supply. That is, the current fed into the stimulation coil is a pulsed current with adjustable frequency and amplitude.

[0034] The current frequency flowing through the magnetic stimulation coil is the switching frequency of the IGBT in the frequency adjustment circuit. In this application, the set frequency range is 0 - 50 Hz. The magnitude of the pulsed current amplitude on the magnetic stimulation coil is determined by the DC regulated power supply. By adjusting the output of the DC regulated power supply, the amplitude of the pulsed current is maintained within the range of 50 - 100 A to ensure that the coil can generate a sufficient magnetic field.

[0035] Since the equivalent circuit of the magnetic stimulation coil is a combined circuit of a resistor and an inductor in series, and the inductance component will affect the phase of the stimulation current, which may cause certain errors in frequency adjustment and current amplitude. To eliminate this influence, it is necessary to compensate for the inductance. The compensation method is to connect a capacitor in series with the stimulation coil. Using the principle that the capacitor and the inductor resonate at a certain frequency, the influence of the inductor is thus eliminated. The specific calculation formula is: In the formula, f represents the frequency at which resonance occurs. According to the pulse width of the pulsed current applied to the stimulation coil being 0.5 ms, f = 1000 Hz can be calculated. L represents the inductance value in the stimulation coil, and C represents the value of the series capacitor. From the above formula, it can be seen that when resonance occurs, Z = R. At this time, the stimulation coil is equivalent to a resistor, and the current on the stimulation coil has a maximum value.

[0036] After the coil size is designed in advance in this application, the inductance of the coil is measured by a bridge, and the value of the capacitor to be compensated is calculated through the above formula. Since the coil itself has resistance, there is no need to connect a resistor in series in the circuit, which can reduce the impedance and thus ensure the stimulation effect.

[0037] In this embodiment, the solid-state switch IGBT is selected as the component of each switching tube. According to the voltage withstand and current withstand requirements of each IGBT, the SKM100GB07E3 half-bridge IGBT module is selected in this embodiment. The voltage withstand VCES of this IGBT single tube is 650 V, the DC current withstand IC is 128 A at T = 20 °C, 97 A at T = 80 °C, and the maximum pulsed current ICRM = 300 A.

[0038] In some embodiments, the magnetic stimulation coil has a D-shaped structure, which includes two D-shaped skeletons with different diameters and the excitation coils wound on the two D-shaped skeletons. One end of the excitation coil is connected to the frequency adjustment circuit through a second capacitor, and the other end is respectively connected to the frequency adjustment circuit and the rectification circuit. The bottom end face of the stimulation coil is the stimulation surface and is attached to the position of the user's cervical vagus nerve; Figure 6Figure 0 is the simulation diagram of the coil without chamfering. It can be seen from the figure that due to the lack of chamfering, a large amount of charge accumulates at the tip of the magnetic stimulation coil, and heat generation occurs in this area. Therefore, in order to avoid this situation, in this embodiment, the inner and outer peripheral edges of the magnetic stimulation coil are both provided with rounded corners to prevent a large amount of charge from accumulating at the tip and causing serious coil heating.

[0039] Specifically, in this embodiment, the structure of the magnetic stimulation coil is as Figure 2 shown. Since the coil structure is similar to the capital letter "D" in English, it is hereinafter referred to as the D-shaped coil. The front view of the D-shaped coil is as Figure 3 shown, which is composed of the difference set of two semi-circles. Among them, the radius of the outer semi-circle is 75 mm, the radius of the inner semi-circle is 40 mm, the coil thickness is 25 mm, and the number of turns of the coil is 80. In order to prevent the uneven induction electric field, chamfering treatment is performed on the diameter positions of the outer and inner semi-circles in the front view. The treatment method is: a rounded corner with a radius of 10 mm is taken for the outer semi-circle, and a rounded corner with a radius of 5 mm is taken for the inner semi-circle. The bottom view of the coil is as Figure 4 shown, with a shape of a rectangle with a length of 15 cm and a width of 25 mm. Due to the chamfering treatment, the part in contact with the user's neck is a rectangle with a length of 13 cm and a width of 25 mm. The coil is wound with copper wire with a wire diameter of 2.5 mm. As described above, the coil is connected in series with a capacitor and then connected to the circuit. The inductive component of the coil resonates with the capacitor to eliminate the influence of the coil inductance. A pulsed current with a frequency of 0 - 50 Hz is passed through the magnetic stimulation coil, the pulse width of the pulsed current is 0.5 ms, and the magnetic stimulation coil is arranged at the position of the vagus nerve in the user's neck.

[0040] The magnitude of the pulsed current is controlled by adjusting the output voltage of the DC regulated power supply. The expression of each pulse is Asin(2πf×t), where A represents the current amplitude and f represents the frequency calculated from the pulse width. In this design, according to the pulse width of 0.5 ms, f is calculated to be 1000. The frequency of the pulses in the stimulation coil is 0 - 50 Hz.

[0041] Use Matlab simulation software to build a stimulation circuit verification scheme as shown in Figure 1 to verify the feasibility of the scheme. After simulation, the feasibility of the design scheme is verified, that is, the stimulation circuit can generate the stimulation current with the required amplitude and frequency. Use Comsol simulation software to perform simulation analysis on the D-shaped coil, and the obtained target focusing area is as shown in Figure 5 . Compared with the focusing area diagram of the existing figure-eight magnetic stimulation coil in Figure 7 , this focusing area covers the vagus nerve in the user's neck, has good focusing performance and high stimulation intensity, meeting the design expectations.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

[0043] Embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the embodiments of this application shall be included within the protection scope of this application.

Claims

1. A vagus nerve magnetic stimulation system, characterized in that: It includes a connected inverter circuit, a rectifier circuit, a frequency adjustment circuit and a magnetic stimulation coil, wherein the magnetic stimulation coil is arranged at the position of the vagus nerve in the user's neck; The inverter circuit is connected to a DC regulated power supply to provide power supply. The inverter circuit is connected through a first control module, and the first control module is configured to drive the inverter circuit through an output control signal; The frequency adjustment is connected through a second control module, and the second control module is configured to drive the frequency adjustment circuit to turn on and off through an output control signal, thereby adjusting the frequency of the magnetic stimulation coil.

2. The vagus nerve magnetic stimulation system according to claim 1, characterized in that, The first control module and the second control module include: A control circuit and a drive circuit connected to the control circuit. The control circuit includes a control chip configured to generate a pulse signal with a fixed frequency. The pulse signal is transmitted to the drive circuit through an optocoupler isolation boost circuit, and the drive circuit outputs a drive signal to drive the inverter circuit or the frequency adjustment circuit.

3. The vagus nerve magnetic stimulation system according to claim 2, characterized in that: The rectifier circuit is an LC rectifier circuit composed of an LC filter and a diode. The LC filter is configured to rectify and filter the signal output by the inverter circuit, and the diode is configured to convert an AC signal into a pulsed DC signal.

4. The vagus nerve magnetic stimulation system according to claim 2, characterized in that: The frequency adjustment circuit is composed of a switching tube, a resistor and a first capacitor to output a pulse current with an adjustable frequency of 0-50 Hz.

5. The vagus nerve magnetic stimulation system according to claim 1, characterized in that: The magnetic stimulation coil has a D-shaped structure, which includes two D-shaped skeletons with different diameters and an exciting coil wound on the two D-shaped skeletons. One end of the exciting coil is connected to the frequency adjustment circuit through a second capacitor, and the other end is respectively connected to the frequency adjustment circuit and the rectifier circuit.

6. The vagus nerve magnetic stimulation system according to claim 5, characterized in that: The bottom end face of the magnetic stimulation coil is the stimulation surface and fits to the position of the vagus nerve in the user's neck.

7. The vagus nerve magnetic stimulation system according to claim 5, characterized in that: The inner and outer peripheral edges of the magnetic stimulation coil are both provided with rounded corners.

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