Noninvasive deep time domain interference electrical stimulation system and method applied to spinal cord rehabilitation

Abstract

The invention discloses a noninvasive deep time domain interference electrical stimulation system and method applied to spinal cord rehabilitation, and belongs to the technical field of medical instruments. Difference frequency current is output through the two groups of electrode pairs connected to the electrical stimulator body, so that time domain interference stimulation is generated for the spine, and difference frequency envelope is generated in human tissue. Moreover, the lead wire connected with the electrode is provided with the length scale, so that measurement can be conveniently carried out on the skin on the surface of the spine, and the placement position of the electrode on the surface of the back skin can be quickly determined. The invention further provides an electrical stimulation parameter optimization method, an optimal electrode placement scheme can be quickly generated for a target object, and the difficulty of performing spinal cord rehabilitation by using noninvasive deep time domain interference electrical stimulation clinically is greatly simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a non-invasive deep time-domain interferometric electrical stimulation system and method for spinal cord rehabilitation. Background Art

[0002] Temporal Interference (TI) is a new type of neuromodulation technology. Its core is to use a specific current output method to achieve non-invasive stimulation of deep tissues of the human body. Two pairs of electrodes are placed on the surface of the skin to output currents of different frequencies (several thousand hertz). When these two sets of currents of different frequencies propagate inside human tissues, a unique difference frequency envelope is generated based on the principle of interference. The frequency range of this difference frequency envelope is between a few hertz and tens of hertz, and it is this difference frequency envelope that can penetrate deep into human tissues and stimulate deep areas. This unique working method enables time-domain interference stimulation technology to break through the limitations of traditional neuromodulation technology in stimulation depth, and achieve effective intervention in deep tissues of the human body without invasive operations. In the field of disease treatment, time-domain interferometric stimulation can stimulate the brain and damaged nerve tissue, effectively promote the recovery of neurological function in stroke patients, and alleviate limb movement disorders in patients with spinal injuries; in the field of cognitive function improvement, time-domain interferometric stimulation technology can regulate brain neural activity, improve the cognitive function of people with cognitive impairment such as early-stage Alzheimer's disease patients, and also has the potential to improve learning and work efficiency and enhance the brain's information processing capabilities for normal people.

[0003] The current time-domain interferometric electrical stimulation hardware devices are all designed for the head, and there is a lack of time-domain interferometric electrical stimulation systems specifically for the spine. Due to the differences in the structure and electrical properties of the human head and trunk tissues, the time-domain interferometric electrical stimulation hardware devices designed for the head are not completely suitable for spinal electrical stimulation, and there will be certain difficulties in output indicators and electrode placement. Due to the principle that time-domain interferometric stimulation produces a difference frequency envelope inside human tissue, it is difficult to predict the electric field distribution inside human tissue by artificially selecting the electrode position, and the electric field distribution inside the human body is often observed through simulation. However, there is currently no electric field simulation and parameter optimization process for time-domain interferometric electrical stimulation of the spine, which will cause great difficulties in the clinical application of time-domain interferometric stimulation of the spine. Summary of the invention

[0004] The purpose of the present invention is to solve the problem in the prior art that it is difficult to apply time-domain interferometric stimulation to the spine clinically, and to provide a non-invasive deep time-domain interferometric electrical stimulation system and method for spinal cord rehabilitation.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In the first aspect, the present invention provides a non-invasive deep time-domain interference electrical stimulation system for spinal cord rehabilitation, which includes an electrical stimulator body and two groups of electrode pairs connected to the electrical stimulator body; the bottom surface of the electrical stimulator body is a layout plane for fitting and fixing on the surface of the spinal skin, and each group of electrode pairs consists of two electrodes; all electrodes are independently connected to the electrical stimulator body through flexible and bendable lead wires, and the lead wires are provided with length scales required for positioning, and the four electrodes can be positioned and arranged with the electrical stimulator body as a reference through the length scales on the lead wires, so that the two electrodes in each group of electrode pairs are arranged in a mirror-symmetrical manner along the first center line of the layout plane of the electrical stimulator body, and the two groups of electrode pairs are arranged in a mirror-symmetrical manner along the second center line of the layout plane of the electrical stimulator body, and the first center line and the second center line are perpendicular to each other; the electrical stimulator body outputs the same current frequency to the two electrodes in each group of electrode pairs, but there is a frequency difference and phase difference between the two groups of electrode pairs.

[0007] As a preferred embodiment of the above-mentioned first aspect, an electrical stimulation control unit and a power management unit are integrated inside the electrical stimulator body; the electrical stimulation control unit has multiple output channels, different output channels are connected to the electrodes through different lead wires, and the constant current value, frequency and waveform type of the signal output from each output channel support custom adjustment; the power management unit is connected to the electrical stimulation control unit for supplying power to the electrical stimulation control unit.

[0008] As a preferred embodiment of the above-mentioned first aspect, the power management unit includes a battery module, a charging management module and a level conversion module; the level conversion module is connected between the battery module and the electric stimulation control unit, and is used to convert the output voltage of the battery module into the input voltage required by the electric stimulation control unit; the charging management module is connected between the electric stimulation control unit and the battery module, and is used to realize real-time monitoring of the battery module status and feed back the monitoring information to the electric stimulation control unit.

[0009] As a preferred embodiment of the first aspect, a safety protection unit is also integrated inside the electrical stimulator body, and the safety protection unit includes one or more of an electrode detachment detection module, an inter-electrode short circuit protection module, and a power reverse connection protection module.

[0010] As a preferred embodiment of the first aspect, the outer shell of the electrical stimulator body is provided with an angle scale, and the lead wire of each electrode can independently rotate around the outer shell to change the angle between the lead wire and the horizontal center line of the electrical stimulator body.

[0011] As a preferred embodiment of the above-mentioned first aspect, the two electrodes in each group of electrode pairs are arranged in mirror symmetry along the horizontal center line of the layout plane of the electric stimulator body, and the two groups of electrode pairs are arranged in mirror symmetry along the vertical center line of the layout plane of the electric stimulator body, and the angles between the four electrodes and the horizontal center line are all 45°.

[0012] As a preferred embodiment of the first aspect, a fixing component of an adhesive tape is provided on the layout plane of the electrical stimulator body.

[0013] As a preferred embodiment of the first aspect, the outer shell of the electrical stimulator body is provided with a power indicator light, an operation status indicator light and a power switch.

[0014] In a second aspect, the present invention provides a method for optimizing electrical stimulation parameters of a non-invasive deep time-domain interferometric electrical stimulation system as described in any one of the solutions of the first aspect, comprising:

[0015] S1, reading a torso plain scan image of a target object obtained by torso MRI or CT plain scan, performing tissue segmentation on the image, and establishing a human torso model consisting of the segmented organs and tissues;

[0016] S2. Based on the human body trunk model, electrode models corresponding to the four electrodes are modeled, and then the human body trunk model with the electrode model is meshed by finite element to generate a tetrahedral mesh, and parameters are assigned to each tissue and organ to form a finite element model;

[0017] S3. According to the pre-specified spinal cord target position, the point closest to the spinal cord target position is found on the skin surface of the back of the trunk of the finite element model as the origin, and then a finite element simulation is performed for each group of candidate layout positions of the four electrodes; during the finite element simulation, the four electrode models in the finite element model are first adjusted to their respective candidate layout positions, and each group of candidate layout positions needs to ensure that the four electrode models are arranged in a mirror-symmetrical manner along both sides of the spine on the skin surface of the back of the trunk, and at the same time, they need to be arranged in a mirror-symmetrical manner along a straight line passing through the origin and perpendicular to the direction of the spine, and then a stimulation current that meets the preset parameters is simulated and applied to the four electrodes, and a fixed current frequency is applied to the two electrodes in each group of electrode pairs, but there is a frequency difference and a phase difference in the current frequency applied between the two groups of electrode pairs, and the electric field intensity distribution generated by all electrodes at the spinal cord target position under each group of candidate layout positions is obtained through simulation;

[0018] S4. Based on the screening principle of maximizing the electric field intensity distribution that can be generated at the spinal cord target area, the best layout position is selected from all candidate layout positions, and each group of best layout positions is converted into relative position parameters of the four electrodes when the electrical stimulator body is used as the reference position, and output as the final optimization result.

[0019] As a preferred embodiment of the second aspect, the relative position parameter is a horizontal projection component and a vertical projection component of the length of a line connecting each electrode to the origin.

[0020] As a preferred embodiment of the second aspect, the relative position parameter is the length of a line connecting each electrode to the origin and a relative rotation angle of the line in a coordinate system.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The time-domain interference electrical stimulation hardware system designed by the present invention for non-invasive spinal cord electrical stimulation outputs a difference frequency current through two sets of electrode pairs connected to the electrical stimulator body, thereby generating time-domain interference stimulation for the spine and generating a difference frequency envelope inside the human tissue. Moreover, the present invention has a length scale on the lead wire connected to the electrode, so that it is convenient to measure on the skin on the surface of the spine and quickly determine the placement of the electrode on the back skin surface. In addition, the lead wire and the electrode sheet structure can also be designed to be connected in a detachable form so that the lead wire can be reused.

[0023] (2) The present invention performs tissue segmentation through MRI / CT trunk imaging to obtain the patient's individualized trunk tissue structure information, thereby establishing an individualized electromagnetic simulation model for the patient, and performing electric field simulation of time-domain interferometric stimulation of the spine based on this model, which can significantly improve the accuracy of the simulation results.

[0024] (3) The present invention determines the positions of two pairs of electrodes by taking the back skin surface position closest to the spinal target area as the origin, setting the horizontal projection component and vertical projection component of the electrode from the origin, or the distance from the electrode to the origin and the offset angle. After obtaining the optimal position parameters corresponding to each electrode through parameter optimization, medical staff can determine the origin by touching the position of the spine, and locate the placement of each electrode through the scale on the device. This approach can quickly apply the optimal electrode placement scheme in clinical practice, greatly simplifying the difficulty of clinical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of a time domain interferometric electrical stimulation system for non-invasive spinal cord electrical stimulation of the present invention;

[0026] Figure 2 It is a schematic diagram of a specific circuit composition of a time domain interference electrical stimulation system applied to non-invasive spinal cord electrical stimulation in an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the appearance structure of a time domain interference electrical stimulator used for non-invasive spinal cord electrical stimulation in an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the appearance structure of another time domain interference electrical stimulator with a scale on the housing used for non-invasive spinal cord electrical stimulation in an embodiment of the present invention;

[0029] Figure 5 It is the result map of tissue segmentation using individual patient MRI / CT images;

[0030] Figure 6 It is a flow chart for optimizing the treatment parameters of individualized time-domain interferometric electrical stimulation for non-invasive spinal cord electrical stimulation;

[0031] Figure 7 is a schematic diagram of three spinal cord target area locations and candidate electrode locations selected in an embodiment of the present invention;

[0032] Figure 8 is a diagram showing the optimization results of individualized time-domain interferometric electrical stimulation treatment parameters for non-invasive spinal cord electrical stimulation in an embodiment of the present invention;

[0033] Fig. 9 This is a comparison chart of the simulation results of time domain interference stimulation and traditional epidermal electrical stimulation.

[0034] In the figure: electrical stimulation control unit 1, electrode detachment detection module 2, lead wire 3, electrode 4, inter-electrode short-circuit protection module 5, power reverse connection protection module 6, level conversion module 7, charging management module 8, battery module 9, electrical stimulator body 10, power indicator light 11, operation status indicator light 12, power switch 13, horizontal center line 14, vertical center line 15. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0036] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0037] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for the purpose of distinction and description, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0038] For the convenience of describing the present invention, the vertical direction is defined in the present invention as the direction of the vertical axis perpendicular to the sagittal transverse plane (also called the horizontal plane) when the human body is standing, and the horizontal direction is the coronal axis direction perpendicular to the sagittal plane when the human body is standing.

[0039] like Figure 1 As shown, in a preferred embodiment of the present invention, a non-invasive deep time-domain interference electrical stimulation system for spinal cord rehabilitation is provided, which includes an electrical stimulator body 10 and two groups of electrode pairs connected to the electrical stimulator body 10. The electrical stimulator body 10 is an electronic device used to output stimulation current to the stimulation electrode according to the needs of spinal cord rehabilitation for electrical stimulation. The bottom surface of the electrical stimulator body 10 is a layout plane, and the entire electrical stimulator body 10 can be fixed on the surface of the spine skin through the layout plane. Connected to the electrical stimulator body 10 are two groups of electrode pairs, each group of electrode pairs consists of two electrodes 4, so there are a total of four electrodes 4. All electrodes 4 are independently connected to the electrical stimulator body 10 through a flexible and bendable lead wire 3, and the lead wire 3 has a length scale required for positioning. The four electrodes 4 can be positioned and arranged with the electrical stimulator body 10 as a reference through the length scale on the lead wire 3. In actual use, the layout plane of the electrical stimulator body 10 can be first fixed on the surface of the spine skin by adhesive or other auxiliary fixing equipment, and then the position of the electrical stimulator body 10 is used as the reference position, and the lead wire 3 of the electrode 4 is moved and positioned in contact with the skin surface. A preferred positioning method is based on the triangle positioning method. Assuming that the reference position coordinate is the origin (0,0), and the electrode 4 needs to be arranged at the (x,y) position, the lead wire 3 can be first tensioned along the X-axis direction, and then the scale position a with a distance of x from the origin (0,0) is found according to the length scale on the lead wire 3, and the lead wire 3 is pressed at the scale position a, and then the free end is bent and tensioned along the Y direction, and then the scale position b with a distance of y from the scale position a is found according to the length scale on the lead wire 3. The scale position b is the layout position of the electrode 4. Since the lead wire 3 only plays a positioning role, the lead wire 3 can be released after the electrode 4 is attached to this layout position, and there is no need to keep it in a vertically bent state at the scale position a. The lead wire 3 connected to the electrode 4 in the present invention has a length scale, so it can be easily and accurately positioned on the skin on the surface of the spine.

[0040] In addition, the electrode 4 and the lead wire 3 and the electrical stimulator body 10 and the lead wire 3 are preferably designed to be detachable, so as to facilitate replacement of the electrode 4 or the lead wire 3.

[0041] In addition, since two groups of four electrodes 4 are connected to the electrical stimulator body 10 of the present invention, in order to generate time domain interference stimulation for the spine and thus generate a difference frequency envelope inside the human tissue, the present invention has certain requirements for the relative positions of the four electrodes 4 after final positioning, and specifically needs to satisfy the following relative relationship: the two electrodes 4 in each group of electrode pairs are arranged in a mirror-symmetrical manner along the first center line of the arrangement plane of the electrical stimulator body 10, and the two groups of electrode pairs are arranged in a mirror-symmetrical manner along the second center line of the arrangement plane of the electrical stimulator body 10, and the first center line and the second center line are perpendicular to each other.

[0042] It should be noted that the above-mentioned first center line and second center line are both center lines of the layout plane of the electrical stimulator body 10. When the electrical stimulator body 10 is attached to the back skin surface, its layout plane can be regarded as parallel to the coronal plane. The first center line can be a horizontal center line along the horizontal direction in the layout plane, or it can be a vertical center line along the vertical direction. If the first center line is a horizontal center line, the second center line is a vertical center line, and conversely, if the first center line is a vertical center line, the second center line is a horizontal center line. Whether the first center line selects a horizontal center line or a vertical center line, the relative positions of the two electrodes 4 constituting each group of electrode pairs will be different. If the first center line selects a horizontal center line, the two electrodes 4 on the left side of the spine constitute a group of electrode pairs, and the two electrodes 4 on the right side of the spine constitute another group of electrode pairs; if the first center line selects a vertical center line, the two electrodes 4 above the electrical stimulator body 10 constitute a group of electrode pairs, and the two electrodes 4 below the electrical stimulator body 10 constitute another group of electrode pairs, and the two electrodes 4 located on the same side of the spine belong to different electrode pairs.

[0043] At the same time, in addition to the above-mentioned four electrodes 4 needing to meet certain relative position requirements, the stimulation parameters of the four electrodes 4 must also meet certain requirements, as follows: the electrical stimulator body 10 outputs the same current frequency to the two electrodes 4 in each group of electrode pairs, but there is a frequency difference and phase difference between the two groups of electrode pairs.

[0044] Generally speaking, the output current frequency of the electrode 4 is at the kilohertz level, and the frequency difference between the two electrode pairs is in the range of a few hertz to several hundred hertz. The specific stimulation parameters need to be determined in advance by the doctor based on clinical experience or simulation results. In the embodiment of the present invention, it is preferred to control the output frequency of each electrode 4 to be 500-8000 Hz, the frequency difference between the two electrode pairs to be 5-200 Hz, and the phase difference to be 0-90°.

[0045] The above-mentioned electrical stimulator body 10 can theoretically be implemented by any existing electrical stimulation device, as long as it can output stimulation current to the stimulation electrode according to the needs of spinal cord rehabilitation for electrical stimulation. In a preferred embodiment of the present invention, a specific implementation method is provided, in which the electrical stimulator body 10 integrates an electrical stimulation control unit 1, a power management unit and a safety protection unit, wherein the power management unit includes a battery module 9, a charging management module 8 and a level conversion module 7, and the safety protection unit includes an electrode detachment detection module 2, an inter-electrode short circuit protection module 5, and a power reverse connection protection module 6. Figure 2 As shown, the circuit connection relationship between the electrical stimulator body 10 including these functional modules and the lead wire 3 and the electrode 4 is shown. Among them, the electrical stimulation control unit 1 has multiple output channels, and different output channels are connected to the electrode 4 through different lead wires 3. The constant current value, frequency and waveform type of the signal output from each output channel support custom adjustment. Therefore, the above-mentioned electrical stimulation control unit 1 should integrate a microcontroller, a constant current source, a waveform generator, a high-voltage pump and multiple channel signal output interfaces. Only simple C language programming is required to achieve 0~250kHz sine wave, square wave, triangle wave and other waveform outputs, and the maximum current and maximum voltage values ​​must meet the requirements of electrical stimulation. Time domain interference electrical stimulation can be achieved without power isolation between the multiple output channels of the electrical stimulation control unit 1. There are a series of existing commercially available products for the electrical stimulation control unit 1, such as the A, A2, and A3 models of the programmable universal stimulation chip ENS001 series produced by Nuanxinjia, with a maximum current of 40mA and a maximum voltage of 55V. Of course, in addition to using commercially available chip modules, the electrical stimulation control unit 1 can also be realized by self-design and processing.

[0046] Continue to see Figure 2 As shown, the power management unit is connected to the electrical stimulation control unit 1, and is mainly used to supply power to the electrical stimulation control unit 1. The level conversion module 7 is connected between the battery module 9 and the electrical stimulation control unit 1, and is used to convert the output voltage of the battery module 9 into the input voltage required by the electrical stimulation control unit 1. The charging management module 8 is connected between the electrical stimulation control unit 1 and the battery module 9, and is used to realize real-time monitoring of the state of the battery module 9 and feed back the monitoring information (such as power and battery voltage, etc.) to the electrical stimulation control unit 1. In an embodiment of the present invention, the power input end of the electrical stimulation control unit 1 is connected to the output end of the level conversion module 7 to obtain a stable working voltage, and its multi-channel signal output interface is connected to the four lead wires 3 to lead the output current to the electrode 4. The charging voltage of the battery module 9 can be set according to actual conditions. In an embodiment of the present invention, the charging voltage can be set to 4.2V.

[0047] Meanwhile, continue to see Figure 2As shown, in order to ensure the effect and safety of electrical stimulation, the electrical stimulator body 10 also integrates safety protection modules such as an electrode detachment detection module 2, an inter-electrode short-circuit protection module 5, and a power supply reverse connection protection module 6. The electrode detachment detection module 2 connects the electrical stimulation control unit 1 and each electrode 4 to realize the electrode state detection during the stimulation process. When an electrode detaches, it will feedback to the electrical stimulation control unit 1, and then issue an alarm or suspend the electrical stimulation program. A short-circuit protection module 5 should be designed between multiple electrodes 4 to prevent the short-circuit recoil current from damaging the electrical stimulation control unit 1. In addition, a power supply reverse connection protection module 6 is designed for the power supply circuit to prevent misoperation from causing power reverse connection, thereby damaging the internal electronic devices.

[0048] However, it should be noted that the above-mentioned power management unit and security protection unit can be selectively configured according to actual functional requirements, and the implementation method in the above-mentioned embodiment is only a preferred method and is not a necessary component.

[0049] In addition, the shape and structure of the above-mentioned time domain interference electrical stimulation system for non-invasive spinal cord electrical stimulation can also be designed according to actual needs.

[0050] like Figure 3 As shown, a schematic diagram of a preferred structure of the above-mentioned time-domain interference electrical stimulation system in an embodiment of the present invention is shown. The electrical stimulator body 10 is in the shape of a flat cylinder, with a red power indicator light 11 on the top, which lights up when the power is on and turns off when the power is off. The power switch 13 on the side is used to control the power on and off; at the same time, there is a color-changing working status indicator light 12 on the top. In a typical application, the working status indicator light 12 is green for normal operation and yellow for system failure. The bottom surface of the electrical stimulator body 10 is a layout plane for fitting to the skin surface of the spine for fixation. A groove can be machined on the layout plane for placing adhesive stickers, so as to fix the electrical stimulator body 10 as a whole on the skin position on the surface of the spine. Continue to see Figure 3As shown, the four electrodes 4 are distributed in mirror symmetry with the horizontal center line 14 and the vertical center line 15 of the bottom layout plane of the electrical stimulator body 10. Among the four electrodes 4, the two electrodes 4 on the left side of the vertical center line 15 constitute a group of electrode pairs with the same electrical stimulation parameters, and the two electrodes 4 on the right side of the vertical center line 15 constitute another group of electrode pairs with the same electrical stimulation parameters. The lead wire 3 has a length scale to facilitate electrode positioning. The scale on the lead wire 3 can be used to measure the distance d3 between the electrode sheet 4 and the center point of the electrical stimulator body 10. At the same time, the angle of rotating the lead wire 3 can measure the horizontal mapping value d2 of d3, thereby calculating the vertical mapping value d1 to achieve accurate positioning of the electrode sheet 4. In actual operation, the specific positioning method can adopt the aforementioned triangle positioning method. Medical staff can determine the layout point of the electric stimulator body 10 by touching the position of the spine, and take the center point of the layout plane of the electric stimulator body 10 as the origin (0,0). First, tension the lead wire 3 along the X-axis direction, and then find the scale position a with a distance of x= d2 from the origin (0,0) according to the length scale on the lead wire 3. Press the lead wire 3 at the scale position a, and then bend and tension its free end along the Y direction. Then find the scale position b with a distance of y= d1 from the scale position a according to the length scale on the lead wire 3. The scale position b is the layout position of the electrode 4. At this time, according to the Pythagorean theorem, the distance between the layout position of the electrode 4 and the origin (0,0) must be d3.

[0051] Of course, in addition to using the aforementioned triangle positioning method for two-step positioning, the present invention can also combine angles and lengths for direct positioning. In direct positioning, the distance between the layout position of each electrode 4 and the origin (0,0) is d3, and the angle between the line connecting the two and the horizontal center line 14 is θ, which can be called the offset angle θ. Therefore, for the layout position of each electrode 4, the lead wire 3 can be tightened and rotated to an angle θ with the horizontal center line 14, and then the scale position c with a distance of d3 from the origin (0,0) is found according to the length scale on the lead wire 3. The scale position c is the layout position of the electrode 4.

[0052] In order to adapt to the above-mentioned direct positioning method, in another embodiment of the present invention, another appearance structure of a time domain interference electrical stimulation system with a housing and a scale for non-invasive spinal cord electrical stimulation is shown, as shown in FIG. Figure 4 In the time domain interferometric electrostimulation system, the outer shell edge of the electrostimulator body 10 has a circle of uniform angle scales, which can be used to measure the offset angle θ of the lead wire 3. The length scale on the lead wire 3 can be used to measure the distance d3 between the electrode sheet 4 and the center point of the electrostimulator body 10. The sine value d1 of d3 and the cosine value d2 of d3 and the offset angle θ can be obtained by trigonometric calculation, thereby realizing the precise positioning of the electrode sheet 4.

[0053] Therefore, based on the non-invasive deep time-domain interference electrical stimulation system for spinal cord rehabilitation given in the above embodiments, the present invention can accurately realize the positioning of two sets of electrode pairs on the surface of the back spinal cord skin, and at the same time generate time-domain interference stimulation for the target area of ​​the spine, and generate a difference frequency envelope inside the human tissue. However, the existing electrical stimulation system is often used for the human head, and the electrode can be positioned by an EEG cap. Due to the differences in the structure and electrical characteristics of the human head and trunk tissue, the time-domain interference electrical stimulation hardware equipment designed for the head cannot be directly applied to spinal electrical stimulation. How to arrange the optimal positions of the four electrodes 4 for different target positions to produce the best stimulation effect, there is still no better solution. Due to the principle that time-domain interference stimulation generates a difference frequency envelope inside human tissue, it is difficult to predict the electric field distribution in human tissue through the traditional artificial selection of electrode positions. Therefore, the present invention further provides an electrical stimulation parameter optimization method for time-domain interference electrical stimulation of the spine for the above-mentioned non-invasive deep time-domain interference electrical stimulation system.

[0054] In a preferred embodiment of the present invention, the method for optimizing the electrical stimulation parameters of the non-invasive deep time-domain interferometric electrical stimulation system specifically comprises the following steps:

[0055] S1. Read the torso plain scan image of the target object obtained by torso MRI plain scan or torso CT plain scan, perform tissue segmentation on it, and establish a human torso model composed of the segmented organs and tissues.

[0056] It should be noted that the above process of reading the torso plain scan image can be offline reading or online reading. Offline reading refers to directly reading data from a database storing torso MRI plain scan images or CT plain scan images, and online reading refers to directly reading the collected data in real time from the torso MRI plain scan device or the torso CT plain scan device. The target object in the present invention can be a patient who needs non-invasive deep time domain interferometric electrical stimulation, or other subjects.

[0057] It should also be noted that tissue segmentation of the torso plain scan image can be achieved through existing tissue segmentation models, such as U-Net, UNet++, 3D U-Net, V-Net, etc., and there is no restriction on this.

[0058] S2. On the basis of the human body trunk model, electrode models corresponding to the four electrodes 4 are established, and then the human body trunk model with the electrode model is meshed by finite element to generate a tetrahedral mesh. At the same time, parameters are assigned to each tissue and organ to form a finite element model.

[0059] It should be noted that when assigning parameters to each tissue and organ, it is mainly to assign specific conductivity to each tissue and organ. The conductivity values ​​of different tissues and organs can be determined based on prior knowledge, such as references or other experiments. In addition, similar to conventional finite element simulation, when performing finite element simulation, it is necessary to set the electromagnetic boundary conditions of the finite element model in order to obtain accurate simulation results. Finite element simulation of human body models belongs to the prior art. The specific model construction, meshing operation, parameter assignment, boundary condition setting and other practices can be implemented by referring to the literature in the prior art, and will not be elaborated in detail.

[0060] S3. According to the pre-specified spinal cord target area position, find the point closest to the spinal cord target area position on the back skin surface of the trunk of the finite element model as the origin, and then perform finite element simulation for each group of candidate arrangement positions of the four electrodes 4.

[0061] It should be noted that when performing finite element simulation for each group of candidate arrangement positions of the four electrodes 4, the specific method is as follows:

[0062] First, the four electrode models in the finite element model are adjusted to their respective candidate layout positions. As mentioned above, in order to generate a difference frequency envelope inside the human tissue, the two electrodes 4 in each group of electrode pairs are arranged in a mirror-symmetrical manner along the horizontal center line 14 of the layout plane of the electrical stimulator body 10, and the two groups of electrode pairs are arranged in a mirror-symmetrical manner along the vertical center line 15 of the layout plane of the electrical stimulator body 10. When the upper body of the human body is in an upright state, the spine can be regarded as the vertical center line 15, so each group of candidate layout positions in the finite element model needs to ensure that the four electrode models are arranged in a mirror-symmetrical manner along both sides of the spine on the skin surface of the back of the trunk, and at the same time, they need to be arranged in a mirror-symmetrical manner along a straight line passing through the origin and perpendicular to the direction of the spine. In an embodiment of the present invention, the angles between the four electrodes 4 and the horizontal center line 14 of the layout plane of the electrical stimulator body 10 in each group of candidate layout positions of the four electrodes 4 can be controlled to be 45°, so that the relative positions of the four electrodes only differ in the offset angle θ, but their d1, d2 and d3 are the same.

[0063] Then, after completing the position adjustment of the four electrode models, a stimulation current that meets the preset parameters is simulated and applied to the electrode models corresponding to the four electrodes 4. A fixed current frequency is applied to the two electrodes 4 in each electrode pair, but there is a frequency difference and phase difference in the current frequency applied between the two electrode pairs.

[0064] Finally, the finite element solver was used to perform simulation calculations, so as to obtain the electric field intensity distribution generated by all electrodes at the spinal cord target area under each set of candidate placement positions through simulation.

[0065] S4. Based on the screening principle of maximizing the electric field intensity distribution that can be generated at the spinal cord target area, the best layout position is selected from all candidate layout positions, and each group of best layout positions is converted into relative position parameters of the four electrodes 4 when the electrical stimulator body 10 is used as the reference position, and output as the final optimization result.

[0066] It should be noted that the optimal arrangement positions output as the final optimization result may be one group or multiple groups, which can be adjusted according to actual needs.

[0067] It should be noted that the relative position parameters of the four electrodes 4 with the electrical stimulator body 10 as the reference position are direct parameters used to locate the position of the electrodes 4 on the skin surface after the position of the electrical stimulator body 10 is fixed in actual application. As mentioned above, since the present invention can locate the four electrodes 4 by the triangle positioning method or by the direct positioning method in actual application, the present invention provides two forms of relative position parameters.

[0068] The first relative position parameter is the horizontal projection component and the vertical projection component of the length of the line from each electrode 4 to the origin. This method is applicable to the triangle positioning method. Figure 3 As shown, for the position of each electrode 4, the horizontal projection component is d2, and the vertical projection component is d1. In a preferred embodiment of the present invention, if the angles between the four electrodes 4 and the horizontal center line 14 are all kept at 45°, then the values ​​of d1 and d2 of the four electrodes are the same, and there is no need to solve a set of values ​​for each electrode, which can simplify the simulation process and the operational difficulty in actual clinical application.

[0069] The second relative position parameter is the length d3 of the line from each electrode 4 to the origin and the relative rotation angle of the line in the coordinate system. The coordinate system here refers to a two-dimensional coordinate system with the origin as the center, the horizontal center line 14 as the X axis, and the vertical center line 15 as the Y axis. Therefore, the relative rotation angle in the coordinate system in the second relative position parameter is the aforementioned offset angle θ.

[0070] The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation and the electrical stimulation parameter optimization method shown in S1 to S4 are applied to a specific embodiment to demonstrate their technical effects.

[0071] Example

[0072] In this embodiment, based on Figure 3The noninvasive deep time-domain interferometric electrical stimulation system shown in the figure is modeled, and the first relative position parameter form mentioned above is adopted. The specific process of the electrical stimulation parameter optimization method is shown in S1~S4. The basic steps are not repeated here. The specific practices and technical effects of each step are mainly shown below.

[0073] In this embodiment, as shown in S1 above, it is first necessary to scan and obtain the individual MRI / CT image of the patient, and then use the MRI / CT image to perform tissue segmentation through an algorithm. The specific implementation of a segmentation result is as follows: Figure 5 As shown in FIG. 1 , the segmented organs and tissues include skin, subcutaneous fat, muscle, skeleton, spinal cord, lung, liver, spleen, pancreas, stomach, chest, heart and kidney. After segmentation, all tissues and organs are integrated into a human torso model.

[0074] Then, as shown in S2 above, an electrode model of four electrodes 4 is placed on the back skin surface of the human body trunk model, and then the model is meshed to generate a tetrahedral mesh. Then, a stimulation current satisfying the preset parameters is simulated and applied to the four electrodes 4. In this embodiment, the stimulation current output frequency of the electrode pair on the left side of the spine is set to 1000 Hz, and the stimulation current output frequency of the electrode pair on the right side of the spine is set to 1040 Hz, so that the frequency of the difference frequency envelope between the electrode pairs on both sides is 40 Hz. In addition, in this embodiment, each segmented tissue and organ is given a specific conductivity at 1 kHz, and the conductivity is determined according to the reference value in the literature, as shown in Table 1. Finally, the electromagnetic boundary conditions of the model are set, and the finite element solver is used for calculation.

[0075] Table 1 Electrical conductivity of various tissues and organs at 1 kHz

[0076]

[0077] The process of optimizing the parameters of individualized time-domain interference electrical stimulation therapy for non-invasive spinal cord electrical stimulation in this embodiment is as follows: Figure 6 As shown. It is particularly noted that, in order to simplify the simulation process in this embodiment, all candidate positions of the four electrodes 4 can be determined in advance, and then an electrode model is set at each candidate position, and gridding and parameter assignment are performed together. When performing simulation, only the electrode model corresponding to this group of candidate positions can be activated each time. Since the first relative position parameter form mentioned above is adopted in this embodiment, the position of the spinal cord target area to be stimulated is first determined when performing simulation, and the point on the back skin closest to the target area is used as the origin. The two pairs of electrodes placed at four positions on the back skin surface with horizontal and vertical distances from the origin of d1 and d2 are activated, and time domain interference stimulation electric field simulation is performed, and the average electric field strength generated on the spinal cord target area is calculated. Finally, the electrode placement scheme with the largest average electric field strength generated in the target area is selected to obtain the corresponding d1 and d2 values.

[0078] In a specific example of this embodiment, the diameter of electrode 4 is 10 mm and the thickness is 5 mm. d1 is 10 mm, 21 mm, 32 mm, 43 mm, and 54 mm, and d2 is 10 mm, 25 mm, 40 mm, 55 mm, and 70 mm, respectively. By combining different d1 and d2, 25 different electrode placement schemes can be obtained. At the same time, this embodiment sets three different spinal cord target locations, with the spinal cord areas wrapped by the spine C5, T7, and L3 as the target areas, and the respective electrode placement schemes are as follows: Figure 7 The current of each pair of electrodes was set to 4 mApp. Individualized modeling and simulation were performed for a male patient and a female patient, and the average electric field strength of the spinal cord target area was obtained using 25 different electrode placement schemes in three target areas. Figure 8 As shown. Figure 8 It can be observed from the average electric field strength results shown that for male patients, the optimal d1 and d2 at the C5 target area are 43 mm and 70 mm. The optimal d1 and d2 at the T7 target area are 10 mm and 40 mm. The optimal d1 and d2 at the L3 target area are 10 mm and 70 mm. For female patients, the optimal d1 and d2 at the C5 target area are 21 mm and 55 mm. The optimal d1 and d2 at the T7 target area are 10 mm and 40 mm. The optimal d1 and d2 at the L3 target area are 10 mm and 70 mm.

[0079] In addition, in order to compare the time-domain interferometric electrical stimulation and traditional epidermal electrical stimulation for spinal cord rehabilitation in this embodiment, an exemplary comparative experiment was conducted. The specific method is as follows: the positions of the two pairs of electrodes for time-domain interferometric electrical stimulation correspond to d1 and d2 of 54 mm and 40 mm, and the output current is set to 4 mA. The output current frequencies of the electrode pair on the right side of the spinal cord and the electrode pair on the left side of the spinal cord are 1000 Hz and 1040 Hz, respectively. The position of the traditional epidermal electrical stimulation electrode is set to a horizontal distance of 54 mm from the spinal cord target area, the output current frequency is 1000 Hz, and the size is 8 mA to ensure the same total dose as the time-domain interferometric electrical stimulation group. The simulation results of the final comparative experiment are shown in the figure. Fig. 9 As shown in the figure, the average electric field strength of TDI electrical stimulation and traditional epidermal electrical stimulation in the target area was 0.55 V / m and 0.39 V / cm respectively (41% difference). This proves the advantage of TDI electrical stimulation in treating deep areas.

[0080] In summary, the present invention designs a time-domain interferometric electrical stimulation hardware system for non-invasive spinal cord electrical stimulation, which can realize fast and efficient stimulation treatment of the spinal cord in clinical practice; at the same time, the present invention also formulates an individualized time-domain interferometric electrical stimulation treatment plan design process for non-invasive spinal cord electrical stimulation. By establishing an individualized trunk tissue model and performing electromagnetic simulation, the electrode placement plan corresponding to the maximum average electric field strength in the spinal cord target area is obtained. Combined with the hardware system, a spinal cord time-domain interferometric electrical stimulation treatment that is more suitable for clinical practice can be realized.

[0081] The above-described embodiments are only some preferred implementations of the present invention, but are not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation, characterized in that: The invention comprises an electric stimulator body (10) and two groups of electrode pairs connected to the electric stimulator body (10); the bottom surface of the electric stimulator body (10) is a layout plane for fitting and fixing on the surface of the spinal skin, and each group of electrode pairs is composed of two electrodes (4); all electrodes (4) are independently connected to the electric stimulator body (10) through flexible and bendable lead wires (3), and the lead wires (3) are provided with length scales required for positioning, and the four electrodes (4) can be positioned and arranged with the electric stimulator body (10) as a reference through the length scales on the lead wires (3), so that the two electrodes (4) in each group of electrode pairs are arranged in a mirror-symmetrical manner along the first center line of the layout plane of the electric stimulator body (10), and the two groups of electrode pairs are arranged in a mirror-symmetrical manner along the second center line of the layout plane of the electric stimulator body (10), and the first center line and the second center line are perpendicular to each other; the electric stimulator body (10) outputs the same current frequency to the two electrodes (4) in each group of electrode pairs, but there is a frequency difference and a phase difference between the two groups of electrode pairs.

2. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 1, characterized in that: The electrical stimulator body (10) has an electrical stimulation control unit (1) and a power management unit integrated therein; the electrical stimulation control unit (1) has multiple output channels, different output channels are connected to the electrodes (4) via different lead wires (3), and the constant current value, frequency and waveform type of the signal output from each output channel support custom adjustment; the power management unit is connected to the electrical stimulation control unit (1) and is used to supply power to the electrical stimulation control unit (1).

3. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 2, characterized in that: The power management unit comprises a battery module (9), a charging management module (8) and a level conversion module (7); the level conversion module (7) is connected between the battery module (9) and the electrical stimulation control unit (1) and is used to convert the output voltage of the battery module (9) into an input voltage required by the electrical stimulation control unit (1); the charging management module (8) is connected between the electrical stimulation control unit (1) and the battery module (9) and is used to implement real-time monitoring of the state of the battery module (9) and to feed back the monitoring information to the electrical stimulation control unit (1).

4. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 3, characterized in that: A safety protection unit is also integrated inside the electrical stimulator body (10), and the safety protection unit comprises one or more of an electrode detachment detection module (2), an inter-electrode short circuit protection module (5), and a power supply reverse connection protection module (6).

5. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 1, characterized in that: An angle scale is provided on the outer shell of the electrical stimulator body (10), and the lead wire (3) of each electrode (4) can independently rotate around the outer shell to change the angle between the lead wire (3) and the horizontal center line (14) of the electrical stimulator body (10).

6. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 1, characterized in that: The two electrodes (4) in each group of electrode pairs are arranged in a mirror-symmetrical manner along a horizontal center line (14) of the arrangement plane of the electrical stimulator body (10), and the two groups of electrode pairs are arranged in a mirror-symmetrical manner along a vertical center line (15) of the arrangement plane of the electrical stimulator body (10), and the angles between the four electrodes (4) and the horizontal center line (14) are all 45 degrees.

7. The non-invasive deep time-domain interferometric electrical stimulation system for spinal cord rehabilitation according to claim 1, characterized in that: An adhesive fixing component is provided on the arrangement plane of the electrical stimulator body (10).

8. A method for optimizing electrical stimulation parameters of a non-invasive deep temporal interferometric electrical stimulation system as claimed in claim 1, characterized in that: include: S1, reading a torso plain scan image of a target object obtained by torso MRI or CT plain scan, performing tissue segmentation on the image, and establishing a human torso model consisting of the segmented organs and tissues; S2. Based on the human body trunk model, electrode models corresponding to the four electrodes (4) are modeled, and then the human body trunk model with the electrode model is meshed by finite element to generate a tetrahedral mesh, and parameters are assigned to each tissue and organ to form a finite element model; S3. According to the pre-specified spinal cord target location, the point closest to the spinal cord target location is found on the skin surface of the back of the trunk of the finite element model as the origin, and then a finite element simulation is performed for each group of candidate layout positions of the four electrodes (4); during the finite element simulation, the four electrode models in the finite element model are first adjusted to their respective candidate layout positions, and each group of candidate layout positions needs to ensure that the four electrode models are arranged in a mirror-symmetrical manner along both sides of the spine on the skin surface of the back of the trunk, and at the same time, they need to be arranged in a mirror-symmetrical manner along a straight line passing through the origin and perpendicular to the direction of the spine, and then a stimulation current that meets the preset parameters is simulated and applied to the four electrodes (4). A fixed current frequency is applied to the two electrodes (4) in each group of electrode pairs, but there is a frequency difference and a phase difference in the current frequency applied between the two groups of electrode pairs. The electric field intensity distribution generated by all electrodes at the spinal cord target location under each group of candidate layout positions is obtained through simulation; S4. Based on the screening principle of maximizing the electric field intensity distribution generated at the spinal cord target area, the best layout position is selected from all candidate layout positions, and each group of best layout positions is converted into relative position parameters of the four electrodes (4) with the electrical stimulator body (10) as the reference position, and output as the final optimization result.

9. The method for optimizing electrical stimulation parameters according to claim 8, characterized in that: The relative position parameters are the horizontal projection component and the vertical projection component of the length of the line connecting each electrode (4) to the origin.

10. The method for optimizing electrical stimulation parameters according to claim 8, characterized in that: The relative position parameters are the length of the line connecting each electrode (4) to the origin and the relative rotation angle of the line in the coordinate system.

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