Calculation method for generating multiple physical stimuli in living body based on Matlab magnetoelectric coupling

Abstract

The invention relates to a calculation method for generating various physical stimuli in a living body based on Matlab magnetoelectric coupling. Using CST software to simulate the magnetic induction intensity distribution and the magnetic field direction of the permanent magnet array, and outputting the spatial distribution of the magnetic induction intensity of the calculation area according to a fixed step length; using Sim4Life software to simulate electric field distribution and current density distribution generated in an organism after a load coil is electrified, and outputting current density distribution of a calculation area; matlab software is used for magnetoelectric coupling, the two output files are imported into Matlab, a three-dimensional matrix of a magnetic induction intensity field and a three-dimensional matrix of a current density field are constructed respectively, cross multiplication solving is carried out according to a resultant force calculation formula, the average force density of a target area and the resultant force body density of unit volume are obtained through calculation, and solved numerical values are visualized. According to numerical values of magnetic stimulation, electrical stimulation and mechanical stimulation required in a living body, reasonable permanent magnet array and load coil arrangement are obtained through optimization.

Description

Technical Field

[0001] The invention belongs to the field of multi-physical field coupling calculation, and relates to a calculation method for generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab. Background Art

[0002] Magnetic stimulation, electrical stimulation and mechanical stimulation are commonly used physical therapy methods to promote bone recovery and treat orthopedic diseases such as fractures and osteoporosis. Magnetic stimulation affects the proliferation and differentiation of bone cells through magnetic fields, accelerating fracture healing; while electrical stimulation stimulates cell activity and blood circulation through electric current, promoting the growth and repair of bone tissue. Mechanical stimulation is very important for the treatment of bone diseases. Bones are living tissues that maintain and enhance their structure and function through force. Studies have found that appropriate mechanical stimulation can promote bone growth, increase bone density, improve osteoporosis symptoms, and help rehabilitation treatment. After fracture surgery, applying appropriate mechanical stimulation through physical therapy and rehabilitation training can help accelerate bone healing.

[0003] Common physical therapy is mostly stimulation from a single physical source, including magnetic stimulation and electrical stimulation; common mechanical stimulation methods are mainly external overall stimulation, including exercise, massage, traction and vibration. Multi-physical field coupling can achieve the simultaneous generation of multiple physical stimulations, including mechanical stimulation generated by coupling directly acting on every bone cell in the body, which will get better stimulation feedback. After magnetoelectric coupling, charged particles move at the bone cell level, and under the action of an external magnetic field, a new Lorentz force is generated, achieving the goal of sending mechanical stimulation to every bone cell. However, the theoretical calculation and simulation of mechanical stimulation generated by magnetoelectric coupling are difficult, and there is no specific calculation method to guide device design and biomedical experimental research. The present invention innovatively proposes a calculation method based on Matlab to generate multiple physical stimulations in vivo by magnetoelectric coupling. After multiple experimental optimizations, the accuracy is high, and the value of the Lorentz force generated in the body after magnetoelectric coupling can be obtained, which not only provides optimization guidance for the design and manufacture of magnetoelectric coupling physical therapy devices, but also provides theoretical calculation support for mechanical stimulation research in vivo. Summary of the invention

[0004] Technical issues to be solved

[0005] In order to avoid the shortcomings of the prior art, the present invention proposes a calculation method for generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab.

[0006] Technical Solution

[0007] A calculation method for generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab, characterized by the following steps:

[0008] Step 1: According to the requirements of static magnetic field stimulation in magnetoelectric coupling stimulation, the physical parameters of the permanent magnet are determined, and the CST software is used to simulate the magnetic induction intensity distribution, magnetic induction intensity gradient and magnetic field direction generated by the permanent magnet magnetic circuit in the target area of ​​the organism, and the spatial distribution of the magnetic induction intensity in the calculation area is output according to a fixed step length, which is recorded as output file 1;

[0009] The physical parameters of the permanent magnet include the material and magnetic circuit model of the permanent magnet;

[0010] Step 2: According to the requirements of electromagnetic field stimulation in magnetoelectric coupling stimulation, the physical parameters of the load coil are determined, and the Sim4Life software is used to simulate the magnetic field distribution generated by the load coil and the electric field distribution and current density distribution generated in the target area of ​​the organism. The current density spatial distribution in the calculation area is output according to a fixed step size and recorded as output file 2;

[0011] The physical parameters of the load coil include the material of the coil itself and the arrangement of the coil; they also include the coil input parameters: waveform, duty cycle, and frequency of the electromagnetic wave;

[0012] Step 3: Use Matlab software for magneto-electric coupling, import CST software simulation output file 1 and Sim4Life software simulation output file 2, use Matlab software to construct three-dimensional matrices of magnetic induction intensity field and current density field respectively, solve the two three-dimensional matrices according to the resultant force calculation formula, calculate the average force density of the target area and the resultant force density per unit volume, and visualize the solution values.

[0013] According to the values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation required for the target area in the organism, the permanent magnet material and permanent magnet magnetic circuit model as well as the material, arrangement and input parameters of the load coil are optimized; the preferred conditions are: the magnetic induction intensity of the magnetic stimulation required in the organism must be greater than 1mT, and the current density value of the electrical stimulation must be greater than 1x10 -6 A / m 2 , the mechanical stimulation value is in the range of (1-100) dynes, and when the obtained magnetic stimulation, electrical stimulation and mechanical stimulation values ​​meet the above requirements, the magneto-electrically coupled permanent magnet array and coil arrangement are preferred.

[0014] The direction of the magnetic field generated by the permanent magnet magnetic circuit must satisfy the requirement that the magnetic lines of force are perpendicular to the target area of ​​the biological body, the magnetic induction intensity in the target action area is greater than 1mT, the magnetic field uniformity is good, and the overall mass of the permanent magnet is light; the magnetic circuit models include Halbach type magnetic circuit, flat array type magnetic circuit, volcano type magnetic circuit, "C" type magnetic circuit and "H" type magnetic circuit.

[0015] The steps of simulating the permanent magnet magnetic circuit using the CST software are as follows:

[0016] Start the static magnetic field solution module, establish the permanent magnet magnetic circuit geometric model according to the design dimensions, and establish the solution domain;

[0017] Specify the material properties of the geometric model and set the boundary conditions for the simulation calculation;

[0018] Divide the mesh of magnetic circuit geometric model and solution domain;

[0019] According to the size of the target calculation area, the output magnetic induction intensity distribution space is delineated and the text data of the magnetic induction intensity and magnetic induction intensity gradient with a fixed step length is output;

[0020] According to the magnetic field force formula, the static magnetic force is obtained:

[0021]

[0022] Where: m is the weight of the organism, χ is the magnetic susceptibility of the organism.

[0023] Optimal settings of parameters in the CST software simulation:

[0024] The solution domain is set to a multiple of the maximum radius of the magnetic circuit geometry model, and the boundary condition is selected as the balloon boundary condition to simulate the magnetic field distribution of the permanent magnet in the natural environment;

[0025] Select the material of the permanent magnet, set the relative magnetic permeability μ, magnetic coercivity Hc, remanence Br, and the rest of the solution area is vacuum;

[0026] The grid uses the classic grid division model and grid length; the solution accuracy and allowable error in the solver;

[0027] The magnetic induction intensity distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector components of the magnetic induction intensity corresponding to the three coordinate directions are output respectively. The step size is set and the format is selected as a text document.

[0028] The load coil requires the electric field distribution and magnetic field distribution generated in the body after the coil is energized, and preferably has a coil arrangement with a large electromagnetic field penetration depth and uniform distribution; the coil arrangement methods include solenoid shape, mosquito coil shape, runway shape, 8 shape, four-leaf shape or slinky shape.

[0029] The simulation steps of the Sim4Life software are as follows:

[0030] Import the biological model to be simulated and cut unnecessary model parts;

[0031] Draw the coil according to the calculated target area position;

[0032] Establish a magnetic quasi-static solver and set the current frequency, current magnitude and current direction input into the coil;

[0033] The coil and the organism are meshed separately, and different mesh precisions can be set;

[0034] Build a voxel model and check whether the mesh division is correct;

[0035] According to the size of the target calculation area, the induced current density distribution space output to Matlab is delineated, and the current density Matlab data with a fixed step length is output;

[0036] Calculate the current density: J = πσrBf, where: σ is the conductivity of the conductor, r is the radius of the conductor, B is the magnetic induction intensity generated by the coil, and f is the frequency of the current.

[0037] The preferred settings of the parameters in the Sim4Life software simulation are:

[0038] Select the current form, set the frequency, current size, and current direction;

[0039] The mesh uses the classic meshing model, sets the mesh accuracy of the organism and the mesh accuracy of the coil; the solution accuracy and allowable error in the solver;

[0040] The current density distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector of the current density corresponding to the spatial coordinate are output respectively. The step size is set and the format is selected as Matlab document.

[0041] The steps of the Matlab software magnetoelectric coupling are:

[0042] Import CST output file 1 and Sim4Life output file 2;

[0043] Construct a three-dimensional matrix of magnetic induction intensity distribution of static magnetic field in Matlab;

[0044] Construct a three-dimensional matrix of current density distribution in Matlab;

[0045] Compare the two sets of three-dimensional matrix data, eliminate the data differences, and make the current density and magnetic induction intensity correspond one to one;

[0046] According to the Lorentz force solution formula F = J × B, the two three-dimensional matrices are cross-multiplied to obtain the component forces in the x-coordinate, y-coordinate and z-coordinate directions, and then the average force density is obtained by vector addition;

[0047] The forces in the x-coordinate, y-coordinate, and z-coordinate directions are summed up respectively, and the combined force density is obtained by vector addition;

[0048] Obtain the resultant force of each volume element and visualize the resultant force.

[0049] The Matlab software magnetoelectric coupling combined calculation couples the spatial magnetic induction intensity distribution with the spatial current density distribution to reflect the spatial distribution of the Lorentz force. The calculation process is as follows:

[0050] Reconstruct the matrix of magnetic induction intensity;

[0051] Reconstruct the matrix of current density;

[0052] The force at a point in the X direction is solved using the cross product formula: F x =J y *B z -J z *B y ;

[0053] The force at a point in the Y direction is solved using the cross product formula: F y =J z *B x -J x *B z ;

[0054] The force at a point in the Z direction is solved using the cross product formula: F z =J x *B y -J y *B x ;

[0055] Average force at a point:

[0056] Calculate the resultant forces in the X, Y, and Z directions respectively:

[0057] sumF x =sum(sum(sum(F x )));

[0058] sumF y =sum(sum(sum(F y )));

[0059] sumF z =sum(sum(sum(F z )));

[0060] Find the total force at a point:

[0061]

[0062] The resultant force per unit volume is:

[0063] F v =Fa *v 3 .

[0064] Beneficial Effects

[0065] The present invention proposes a calculation method for generating multiple physical stimulations in a biological body by magnetoelectric coupling based on Matlab, including magnetic stimulation, electrical stimulation and mechanical stimulation. The calculation method is as follows: (1) Use CST software to simulate the magnetic induction intensity distribution and magnetic field direction of a permanent magnet array, and output the spatial distribution of the magnetic induction intensity in the calculation area according to a fixed step length, which is recorded as output file 1; (2) Use Sim4Life software to simulate the electric field distribution and current density distribution generated in the biological body after the load coil is energized, and output the current density distribution in the calculation area, which is recorded as output file 2; (3) Use Matlab software magnetoelectric coupling, import output file 1 and output file 2 in Matlab, and construct three-dimensional matrices of magnetic induction intensity field and current density field respectively, solve them according to the cross multiplication formula of the resultant force calculation formula, calculate the average force density of the target area and the resultant force body density per unit volume, and visualize the solved values. (4) According to the values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation required in the biological body, optimize and obtain a reasonable permanent magnet array and load coil arrangement.

[0066] The calculation method of the magnetoelectric coupling based on Matlab in the present invention for generating various physical stimuli in the biological body is accurate and systematic, and can obtain the numerical values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation generated in the biological body after magnetoelectric coupling, which not only provides optimization guidance for the design and manufacture of magnetoelectric coupling physical therapy devices, but also provides theoretical calculation support for the research of various physical stimulations in the biological body.

[0067] The present invention has undergone multiple experimental optimizations and has a high degree of accuracy. It can obtain the value of the Lorentz force generated in the organism after magnetoelectric coupling, which not only provides optimization guidance for the design and manufacture of magnetoelectric coupling physical therapy devices, but also provides theoretical calculation support for mechanical stimulation research in the organism. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 :Arrangement of the magnetic circuit of the flat array

[0069] Figure 2 :Solution of magnetic induction intensity distribution of flat array magnetic circuit and calculation of magnetic induction intensity at lumbar spine

[0070] Figure 3 : Export of magnetic induction intensity distribution data of flat array magnetic circuit

[0071] Figure 4 :Arrangement of the track-shaped coils in Sim4Life and the relative positions of the coils, magnets, and lumbar spine

[0072] Figure 5 :Solved in Sim4Life to obtain the current density distribution

[0073] Figure 6 : The current density field at the lumbar spine is obtained by solving in Matlab

[0074] Figure 7 : Solve the Lorentz force field at the lumbar spine in Matlab

[0075] Figure 8 :The magnetoelectric coupling device designed using this calculation method

[0076] Fig. 9 :Flowchart of the computational method for generating various physical stimuli in vivo by magnetoelectric coupling based on Matlab DETAILED DESCRIPTION

[0077] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0078] The calculation method of generating multiple physical stimulations in vivo by magnetoelectric coupling based on Matlab is characterized by: using CST software to simulate the magnetic induction intensity distribution and magnetic field direction of the permanent magnet array, using Sim4Life software to simulate the electric field distribution and current density distribution of the load coil, and using Matlab software magnetoelectric coupling to calculate the average force density of the target area in the organism and the resultant force density per unit volume. According to the values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation required in the organism, the reasonable permanent magnet array and load coil arrangement are optimized.

[0079] Step 1, design the permanent magnet magnetic circuit according to the design requirements of the permanent magnet, use CST software to simulate the magnetic induction intensity distribution, magnetic induction intensity gradient and magnetic field direction generated by the permanent magnet array in the target area of ​​the biological body, and output the spatial distribution of the magnetic induction intensity in the calculation area according to a fixed step length, which is recorded as output file 1;

[0080] The magnetic circuit design of the permanent magnet needs to satisfy the requirements that the magnetic lines of force are perpendicular to the target area of ​​the organism, the magnetic induction intensity of the target action area is greater than 1mT, the magnetic field uniformity is good, and the overall mass of the permanent magnet is light. Common magnetic circuit models include Halbach type magnetic circuit, flat array type magnetic circuit, volcano type magnetic circuit, "C" type magnetic circuit and "H" type magnetic circuit.

[0081] Halbach type magnetic circuits are divided into common type, radial type and loop type. The high field strength areas generated by common type and radial type magnetic circuits are mainly distributed on the surface of permanent magnets, while the high field strength areas of loop type magnetic circuits are mainly concentrated at the center of magnet aperture. The magnetic field is symmetrically distributed along the axial section, the center of the magnetic circuit is concentrated, and the magnetic field direction is vertical. "C" type and "H" type magnetic circuits have serious magnetic leakage and poor uniformity of magnetic field. The volcano type magnetic circuit has high magnetic induction intensity in a specific direction and a small radiation range.

[0082] In Example 1, a flat array type magnetic circuit is selected, the uniformity of the magnetic field is good, the depth and width of the radiation are large and the implementation is relatively easy. The target calculation area in the body is the lumbar vertebrae L1-L5.

[0083] The CST software simulation steps are as follows:

[0084] (1) Select the static magnetic field solving module and establish the permanent magnet magnetic circuit geometric model according to the design dimensions ( Figure 1 ), establish the solution domain;

[0085] (2) Specify the material properties of the geometric model and set the boundary conditions for the simulation calculation;

[0086] (3) Divide the grid of the magnetic circuit geometric model and solution domain;

[0087] (4) Establish a solver and set the solution accuracy to solve the problem;

[0088] (5) According to the size of the target calculation area, the output magnetic induction intensity distribution space is delineated, and the magnetic induction intensity text data with a fixed step size is output.

[0089] (6) After the magnetic induction intensity B and the magnetic induction intensity gradient dB / dx are obtained, the magnetic force is calculated according to the magnetic force formula:

[0090]

[0091] Where: m is the weight of the organism, χ is the magnetic susceptibility of the organism.

[0092] The preferred setting of parameters in the CST software simulation (Example 1) is: Figure 2

[0093] (1) The solution domain is set to 20 times the maximum radius of the magnetic circuit geometry model, and the boundary condition is selected as the balloon boundary condition, which can simulate the magnetic field distribution of the permanent magnet in the natural environment;

[0094] (2) The material of the permanent magnet can be NdFeB N35, with a relative magnetic permeability μ of 1.09 and a magnetic coercive force Hc of 859

[0095] kA / m, the remanence Br is 1.215T, and the rest of the solution area is vacuum;

[0096] (3) The grid uses the classic grid division model, and the grid length is 1 / 4 of the default solution grid length; the solution accuracy in the solver can be 0.005, and the allowable error is less than 1%. ;

[0097] (4) The magnetic induction intensity distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector components of the magnetic induction intensity corresponding to the three coordinate directions are output respectively. The step size is set to 1 mm, and the format is selected as a text document. Figure 3 )

[0098] Step 2, select the arrangement of the coil according to the design requirements of the load coil, use Sim4Life software to simulate the magnetic field distribution generated by the load coil and the electric field distribution and current density distribution generated in the organism, and output the current density distribution in the calculation area, which is recorded as output file 2;

[0099] The design requirements of the load coil mainly consider the distribution of the electric field and magnetic field generated in the organism after the coil is energized. Generally, the coil arrangement with a large penetration depth of the electromagnetic field and uniform distribution is preferred. The coil arrangement methods include solenoid shape, mosquito coil shape, runway shape, 8-shaped shape, four-leaf shape and slinky shape.

[0100] Example 1 selects a runway-shaped coil arrangement so that the current density generated by the coil is more evenly distributed and has a greater penetration depth, while maintaining a close fit with the flat array type permanent magnet. According to the height of the permanent magnet of 10 mm, an enameled copper wire with a wire diameter of 1.2 mm is selected, and a total of 4 turns are wound, with 8 turns overlapping and a height of 9.6 mm, which is less than the thickness of the magnet and meets the design requirements.

[0101] The simulation steps of the Sim4Life software are as follows:

[0102] (1) Import the biological model to be simulated and cut out unnecessary parts of the model;

[0103] (2) drawing coils according to the calculated target area position; Figure 4

[0104] (3) Establish a magnetic quasi-static solver and set the current frequency, current magnitude and current direction input into the coil;

[0105] (4) Grid division: the coil and the organism are gridded separately, and different grid accuracies can be set;

[0106] (5) Establish a voxel model and check whether the grid division is correct.

[0107] (6) Solve, according to the size of the target calculation area, define the induced current density distribution space output to Matlab, and output the current density Matlab data with a fixed step size. Figure 5

[0108] The solution formula for current density is: J = πσrBf

[0109] Where: σ is the conductivity of the conductor, r is the radius of the conductor, B is the magnetic induction intensity generated by the coil, and f is the frequency of the current.

[0110] The preferred setting of parameters in the Sim4Life software simulation (Example 1) is:

[0111] (1) The current is in the form of a sinusoidal current, with a frequency of 1 MHz, a current of 10 A, and a direction of clockwise;

[0112] (2) The mesh uses the classic meshing model, with a mesh accuracy of 2 mm for the organism and 1 mm for the coil;

[0113] The solution accuracy in the solver can be 0.005, and the allowable error is less than 1%. ;

[0114] (3) The current density distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector of the current density corresponding to the spatial coordinate are output respectively. The step size is set to 1 mm, and the format is selected as Matlab document.

[0115] In this embodiment, the dynamic magnetic field generated by the current is very small and can be ignored.

[0116] Step 3, use Matlab software for magnetoelectric coupling, import the output file 1 of step 1 and the output file 2 of step 2, and construct the three-dimensional matrices of the magnetic induction intensity field and the current density field respectively, solve them according to the cross multiplication formula of the resultant force calculation formula, calculate the average force density of the target area and the resultant force body density per unit volume, and visualize the solution values.

[0117] The main steps of magneto-electric coupling in Matlab software:

[0118] (1) Import CST output file 1 and Sim4Life output file 2;

[0119] (2) Construct a three-dimensional matrix of magnetic induction intensity distribution of static magnetic field in Matlab;

[0120] (3) Construct a three-dimensional matrix of current density distribution in Matlab;

[0121] (4) Compare the two sets of three-dimensional matrix data, eliminate the data differences, and make the current density and magnetic induction intensity correspond one to one.

[0122] Visualize the current density distribution, Figure 6

[0123] (5) According to the Lorentz force solution formula F = J × B, the two three-dimensional matrices are cross-multiplied to obtain the component forces in the x-coordinate, y-coordinate, and z-coordinate directions, and then the average force density is obtained by vector addition;

[0124] (6) Sum the forces in the x-coordinate, y-coordinate, and z-coordinate directions respectively, and add the vectors to obtain the combined force density;

[0125] (7) Obtain the resultant force of each volume element and visualize the resultant force. Figure 7

[0126] The specific calculation method of the magnetoelectric coupling of the Matlab software is as follows (Example 1):

[0127] (1) The matrix reconstruction method of magnetic induction intensity is as follows (taking the magnetic induction intensity vector component in the x-coordinate direction as an example):

[0128] B x = reshape(B x , [122, 110, 191]);

[0129] (2) The matrix reconstruction method of current density is as follows (taking the current density vector component in the x-coordinate direction as an example):

[0130] J x =Snapshot0(:,1);

[0131] J x =abs(J x )

[0132] J x (isnan(J x ))=0;

[0133] J x = reshape(J x ,[a,b,c]);

[0134] (3) The force at a point in the X direction is solved using the cross product formula:

[0135] F x =J y *B z -J z *B y ;

[0136] (4) Solution for average force density:

[0137]

[0138] avgf=mean(F xyz (:));

[0139] (5) Solution of combined force density:

[0140]

[0141] (6) Solution of volume infinitesimal force:

[0142] v = 0.001;

[0143] F v =F a *v 3 ;

[0144] Step 4, according to the values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation required for the target area in the biological body, optimize the permanent magnet material and permanent magnet array as well as the arrangement mode and input parameters of the load coil.

[0145] The magnetic induction intensity of the magnetic stimulation required in the organism must be greater than 1mT, and the current density of the electrical stimulation must be greater than 1x10 -6 A / m 2 , the mechanical stimulation value is in the range of (1-100) dynes, and when the obtained magnetic stimulation, electrical stimulation and mechanical stimulation values ​​meet the above requirements, the magneto-electrically coupled permanent magnet array and coil arrangement are preferred.

Claims

1. A computational method based on Matlab to generate multiple physical stimuli in a biological body by magnetoelectric coupling, characterized in that Here are the steps: Step 1: According to the requirements of static magnetic field stimulation in magnetoelectric coupling stimulation, the physical parameters of the permanent magnet are determined, and the CST software is used to simulate the magnetic induction intensity distribution, magnetic induction intensity gradient and magnetic field direction generated by the permanent magnet magnetic circuit in the target area of ​​the organism, and the spatial distribution of the magnetic induction intensity in the calculation area is output according to a fixed step length, which is recorded as output file 1; The physical parameters of the permanent magnet include the material and magnetic circuit model of the permanent magnet; Step 2: According to the requirements of electromagnetic field stimulation in magnetoelectric coupling stimulation, the physical parameters of the load coil are determined, and the Sim4Life software is used to simulate the magnetic field distribution generated by the load coil and the electric field distribution and current density distribution generated in the target area of ​​the organism. The current density spatial distribution in the calculation area is output according to a fixed step size and recorded as output file 2; The physical parameters of the load coil include the material of the coil itself and the arrangement of the coil; they also include the coil input parameters: waveform, duty cycle, and frequency of the electromagnetic wave; Step 3: Use Matlab software for magneto-electric coupling, import CST software simulation output file 1 and Sim4Life software simulation output file 2, use Matlab software to construct three-dimensional matrices of magnetic induction intensity field and current density field respectively, solve the two three-dimensional matrices according to the resultant force calculation formula, calculate the average force density of the target area and the resultant force density per unit volume, and visualize the solution values.

2. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: According to the values ​​of magnetic stimulation, electrical stimulation and mechanical stimulation required for the target area in the organism, the permanent magnet material and permanent magnet magnetic circuit model as well as the material, arrangement and input parameters of the load coil are optimized; the preferred conditions are: the magnetic induction intensity of the magnetic stimulation required in the organism must be greater than 1mT, and the current density value of the electrical stimulation must be greater than 1x10 -6 A / m 2 , the mechanical stimulation value is in the range of (1-100) dynes, and when the obtained magnetic stimulation, electrical stimulation and mechanical stimulation values ​​meet the above requirements, the magneto-electrically coupled permanent magnet array and coil arrangement are preferred.

3. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The direction of the magnetic field generated by the permanent magnet magnetic circuit must satisfy the requirement that the magnetic lines of force are perpendicular to the target area of ​​the biological body, the magnetic induction intensity in the target action area is greater than 1mT, the magnetic field uniformity is good, and the overall mass of the permanent magnet is light; the magnetic circuit models include Halbach type magnetic circuit, flat array type magnetic circuit, volcano type magnetic circuit, "C" type magnetic circuit and "H" type magnetic circuit.

4. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The steps of simulating the permanent magnet magnetic circuit using the CST software are as follows: Start the static magnetic field solution module, establish the permanent magnet magnetic circuit geometric model according to the design dimensions, and establish the solution domain; Specify the material properties of the geometric model and set the boundary conditions for the simulation calculation; Divide the mesh of magnetic circuit geometric model and solution domain; According to the size of the target calculation area, the output magnetic induction intensity distribution space is delineated and the text data of the magnetic induction intensity and magnetic induction intensity gradient with a fixed step length is output; According to the magnetic field force formula, the static magnetic force is obtained: Where: m is the weight of the organism, χ is the magnetic susceptibility of the organism.

5. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: Optimal settings of parameters in the CST software simulation: The solution domain is set to a multiple of the maximum radius of the magnetic circuit geometry model, and the boundary condition is selected as the balloon boundary condition to simulate the magnetic field distribution of the permanent magnet in the natural environment; Select the material of the permanent magnet, set the relative magnetic permeability μ, magnetic coercivity Hc, remanence Br, and the rest of the solution area is vacuum; The grid uses the classic grid division model and grid length; the solution accuracy and allowable error in the solver; The magnetic induction intensity distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector components of the magnetic induction intensity corresponding to the three coordinate directions are output respectively. The step size is set and the format is selected as a text document.

6. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The load coil requires the electric field distribution and magnetic field distribution generated in the body after the coil is energized, and preferably has a coil arrangement with a large electromagnetic field penetration depth and uniform distribution; the coil arrangement methods include solenoid shape, mosquito coil shape, runway shape, 8 shape, four-leaf shape or slinky shape.

7. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The simulation steps of the Sim4Life software are as follows: Import the biological model to be simulated and cut unnecessary model parts; Draw the coil according to the calculated target area position; Establish a magnetic quasi-static solver and set the current frequency, current magnitude and current direction input into the coil; The coil and the organism are meshed separately, and different mesh precisions can be set; Build a voxel model and check whether the mesh division is correct; According to the size of the target calculation area, the induced current density distribution space output to Matlab is delineated, and the current density Matlab data with a fixed step length is output; Calculate the current density: J = πσrBf, where: σ is the conductivity of the conductor, r is the radius of the conductor, B is the magnetic induction intensity generated by the coil, and f is the frequency of the current.

8. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The preferred settings of the parameters in the Sim4Life software simulation are: Select the current form, set the frequency, current size, and current direction; The mesh uses the classic meshing model, sets the mesh accuracy of the organism and the mesh accuracy of the coil; the solution accuracy and allowable error in the solver; The current density distribution is output as spatial coordinate data, and the x-coordinate, y-coordinate, z-coordinate and the vector of the current density corresponding to the spatial coordinate are output respectively. The step size is set and the format is selected as Matlab document.

9. The calculation method of generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 1, characterized in that: The steps of the Matlab software magneto-electric coupling are: Import CST output file 1 and Sim4Life output file 2; Construct a three-dimensional matrix of magnetic induction intensity distribution of static magnetic field in Matlab; Construct a three-dimensional matrix of current density distribution in Matlab; Compare the two sets of three-dimensional matrix data, eliminate the data differences, and make the current density and magnetic induction intensity correspond one to one; According to the Lorentz force solution formula F = J × B, the two three-dimensional matrices are cross-multiplied to obtain the component forces in the x-coordinate, y-coordinate and z-coordinate directions, and then the average force density is obtained by vector addition; The forces in the x-coordinate, y-coordinate, and z-coordinate directions are summed up respectively, and the combined force density is obtained by vector addition; Obtain the resultant force of each volume element and visualize the resultant force.

10. The calculation method for generating multiple physical stimuli in a biological body by magnetoelectric coupling based on Matlab according to claim 9, characterized in that: The Matlab software magnetoelectric coupling combined calculation couples the spatial magnetic induction intensity distribution with the spatial current density distribution to reflect the spatial distribution of the Lorentz force. The calculation process is as follows: Reconstruct the matrix of magnetic induction intensity; Reconstruct the matrix of current density; The force at a point in the X direction is solved using the cross product formula: F x =J y *B z -J z *B y ; The force at a point in the Y direction is solved using the cross product formula: F y =J z *B x -J x *B z ; The force at a point in the Z direction is solved using the cross product formula: F z =J x *B y -J y *B x ; Average force at a point: Calculate the resultant forces in the X, Y, and Z directions respectively: sumF x =sum(sum(sum(F x ))); sumF y =sum(sum(sum(F y ))); sumF z =sum(sum(sum(F z ))); Find the total force at a point: The resultant force per unit volume is: F v =F a *v 3 。

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