阅读说明：本技术 一种人工******经皮电能传输系统优化方法 (Method for optimizing percutaneous electric energy transmission system of artificial anal sphincter ) 是由 贾智伟 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种人工肛门括约肌经皮电能传输系统优化方法,涉及应用于医疗器械的电子技术领域,通过对人工肛门括约肌经皮电能传输系统的副边线圈的参数优化设计来实现,步骤如下：1、建立适应于肛门括约肌环境,包含原边线圈和副边线圈轴向与径向不确定因素的经皮电能传输模型；2、基于副边线圈在人体内部的热传导信息,建立对应的体内热传导模型；3、基于人体组织在电磁环境下对电磁的吸收信息,获得原边线圈结构、电流、驱动频率与人体电磁吸收情况之间的相互关系；4、计及体外便携式电源状况、安全性所致传输功率上限与体内装置最低传输功率要求,获得对应条件下副边线圈的最优参数。本发明能实现稳定传输电能,并减少对人体的伤害。(The invention discloses an optimization method of an artificial anal sphincter percutaneous electric energy transmission system, which relates to the technical field of electronics applied to medical instruments and is realized by optimally designing parameters of a secondary coil of the artificial anal sphincter percutaneous electric energy transmission system, and the method comprises the following steps: 1. establishing a percutaneous electric energy transmission model which is suitable for the environment of the anal sphincter and contains uncertain factors of the axial direction and the radial direction of a primary coil and a secondary coil; 2. establishing a corresponding in-vivo heat conduction model based on the heat conduction information of the secondary coil in the human body; 3. based on the electromagnetic absorption information of human tissues in an electromagnetic environment, the mutual relation among the primary coil structure, the current, the driving frequency and the human electromagnetic absorption condition is obtained; 4. and considering the upper limit of transmission power caused by the condition and safety of the portable power supply in vitro and the requirement of the minimum transmission power of the in-vivo device, and obtaining the optimal parameters of the secondary coil under the corresponding conditions. The invention can realize stable electric energy transmission and reduce the harm to human body.)

1. A parameter optimization method for a secondary coil of a percutaneous electric energy transmission system facing an artificial anus is characterized in that system optimization is realized by optimally designing parameters of the secondary coil of the percutaneous electric energy transmission system of the artificial anal sphincter, and the method comprises the following steps:

step 1, establishing a percutaneous electric energy transmission model which is suitable for the environment of anal sphincter and contains uncertain factors of a primary coil and a secondary coil in the axial direction and the radial direction;

step 2, establishing a corresponding in-vivo heat conduction model based on the heat conduction information of the secondary coil in the human body;

step 3, acquiring the correlation among the primary coil structure, the current, the driving frequency and the human body electromagnetic absorption condition based on the electromagnetic absorption information of human body tissues in the electromagnetic environment;

and 4, considering the upper limit of transmission power caused by the condition and safety of the in vitro portable power supply and the minimum transmission power requirement of the in vivo device, and obtaining the optimal parameters of the secondary coil under the corresponding conditions.

2. The method for optimizing parameters of a secondary coil of a percutaneous electric power transmission system facing an artificial anus according to claim 1, wherein the step 1 adopts the principle of electromagnetic induction, a portable power supply, an inverter circuit and the primary coil are arranged outside the body, and the secondary coil, power management and the artificial anal sphincter are implanted in the body.

3. The method for optimizing parameters of a secondary coil of a percutaneous power transfer system facing an artificial anus according to claim 1, wherein the primary coil and the secondary coil are axially and radially uncertain factors of offset and deflection.

4. The method for optimizing parameters of a secondary coil of a percutaneous power transmission system facing an artificial anus according to claim 1, wherein the step 1 further comprises calculating the mutual inductance between the primary coil and the secondary coil, and establishing coordinates by taking the center point of the primary coil as the origin, the axial direction as the y-axis, and the radial direction as the x-axis, wherein the axial distance between the center of the secondary coil and the center of the primary coil is h, the radial distance is r, and the included angle between the secondary coil and the primary coil is θ; the mutual inductance formula between the primary coil and the secondary coil is as follows:

wherein the content of the first and second substances,

mu is the magnetic permeability of the magnetic material,

5. The method for optimizing parameters of a secondary coil of a percutaneous power transmission system facing an artificial anus according to claim 4, wherein h, r and θ are bounded random variables which are uncertain factors in the percutaneous power transmission process, and the maximum coupling transmission efficiency in a full resonance state is as follows:

wherein α is a load factor, Q_P,Q_SAnd the no-load quality factors of the primary coil and the secondary coil are obtained.

6. The method for optimizing parameters of a secondary coil of a percutaneous electric energy transmission system facing an artificial anus as claimed in claim 1, wherein the heat conduction information of the secondary coil in the human body comprises the heat conduction coefficient of the complex environment near the anus.

7. The method for optimizing parameters of a secondary coil of a percutaneous electric energy transmission system facing an artificial anus as claimed in claim 1, wherein the step 2 further comprises the steps of considering the blood perfusion rate of the gastrointestinal tract tissue, describing the heat dissipation condition of the secondary coil in the gastrointestinal tract by using pennes heat transfer equation,heat dissipation power P_rComprises the following steps: p_r＝K_TS₀τ, wherein K_TAs a material-dependent coefficient of heat dissipation, S₀Is the heat dissipation area, tau is the temperature difference with the ambient temperature; when the heating power of the secondary coil is not more than the heat dissipation capacity of the secondary coil, the secondary coil generates heat and does not damage human tissues.

8. The method for optimizing parameters of a secondary coil of a percutaneous power transmission system facing an artificial anus as claimed in claim 1, wherein the step 3 further comprises obtaining the boundary of the excitation frequency and the current for a given primary coil according to a human body electromagnetic dose threshold and the relationship between the human body electromagnetic dose threshold and the excitation frequency and the current.

9. The method for optimizing parameters of a secondary coil of a percutaneous electric energy transmission system facing an artificial anus as claimed in claim 1, wherein the optimal parameters of the secondary coil under the corresponding conditions of step 4 are calculated by the following formula:

Min{V}

wherein V is the secondary coil volume, f and I are the excitation frequency and the current, P_minTo account for the minimum power received at the time of the uncertainty factor, P₀The power required by the system, T is the real-time temperature of the secondary coil, T₀The upper temperature limit for long-term operation is typically 42.5 °, SAR is the local specific absorption rate, and J is the current density.

10. The method for optimizing parameters of a secondary coil of a percutaneous electric energy transmission system facing an artificial anus according to claim 1, wherein the step 4 is further followed by the steps of:

step 5, calculating the transmission power of the optimized secondary coil in a normal working state, and judging whether the minimum transmission power is greater than the preset power and whether the maximum transmission power meets the electromagnetic biological safety and temperature rise safety conditions;

step 6, if the conditions in the step 5 are met, taking the optimized parameters as conventional working information;

and 7, if the condition of the step 5 is not met, returning to the step 1.

The step 4 further comprises:

step 4.1, confirming the correlation with the minimum secondary coil volume which meets the constraint condition from the correlations;

and 4.2, adjusting the structural parameters of the secondary coil according to the mutual relation.

Technical Field

The invention relates to the technical field of electronics applied to medical instruments, in particular to an optimization method of an artificial anal sphincter percutaneous electric energy transmission system.

Background

Anal incontinence is a common clinical condition in anorectal diseases, seriously affecting the quality of life of patients and even causing personality changes. And with the improvement of living standard of people, the disease incidence rate continuously rises, and the influence range and the degree are not underestimated.

Enterostomy, which is the last choice in the world, and artificial anal sphincters are the main methods of surgical treatment of anal incontinence, and the physical and psychological burdens on patients are very heavy. The artificial anal sphincter adopts an artificial organ to treat the disease, and achieves better clinical effect. However, power supply has been a major bottleneck limiting the development of this device, and the percutaneous power transmission technique has shown great advantages in terms of safety and convenience compared to the lead method and the battery method, but the technique has been far from maturity.

Chinese patent document No. CN103683434A, publication No. 2014-03-26, discloses a wireless in-vivo charging system based on percutaneous energy transmission applied to an artificial anal sphincter performing module, comprising: wireless energy transmitting terminal and wireless energy receiving terminal, wherein: the wireless energy transmitting end comprises an inverter circuit and a transmitting coil, and the wireless energy receiving end comprises an LC resonance circuit, a rectifying and filtering circuit and a load circuit. However, the energy transmission system adopts a single magnetic core boss form, so that more magnetic leakage is generated, the coupling efficiency is not ideal, and the energy transmission efficiency is not high.

Chinese patent document No. CN104795905A, published japanese 2015-07-22, discloses a percutaneous energy transmission device for an artificial anal sphincter consisting of a wireless energy transmitting module located outside the body and a sphincter actuating module with a wireless energy receiving module located inside the body. The wireless energy transmitting module comprises an inverter circuit and an energy transmitting coil, and the wireless energy receiving module comprises an energy receiving coil, a compensation capacitor and a rectifying and filtering circuit. The invention can reduce the magnetic resistance between the coils to a certain extent and improve the energy transmission efficiency, but does not consider the electromagnetic safety in the wireless power transmission process and the temperature rise safety caused by the heating of the secondary coil, and the space utilization rate of the secondary coil is low, so that the damage to nearby tissues is larger when the equipment is implanted.

Therefore, those skilled in the art have endeavored to develop a method for enabling the percutaneous electric power transmission system of the artificial anal sphincter to ensure the transmission efficiency and to have less harm to the human body.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides an optimization method of an artificial anal sphincter percutaneous electric energy transmission system, which reduces the volume of a secondary coil and lightens the damage of an implanted device to a human body by optimally designing the parameters of the secondary coil.

In order to achieve the above object, the present invention provides a method for optimizing parameters of a secondary coil of a percutaneous power transmission system for artificial anus, wherein the method for optimizing the secondary coil of the percutaneous power transmission system for artificial anus realizes system optimization by optimally designing the parameters of the secondary coil, and comprises the following steps:

step 1, establishing a percutaneous electric energy transmission model which is suitable for the environment of anal sphincter and contains uncertain factors of a primary coil and a secondary coil in the axial direction and the radial direction;

step 2, establishing a corresponding in-vivo heat conduction model based on the heat conduction information of the secondary coil in the human body;

step 3, acquiring the correlation among the primary coil structure, the current, the driving frequency and the human body electromagnetic absorption condition based on the electromagnetic absorption information of human body tissues in the electromagnetic environment;

and 4, considering the upper limit of transmission power caused by the condition and safety of the in vitro portable power supply and the minimum transmission power requirement of the in vivo device, and obtaining the optimal parameters of the secondary coil under the corresponding conditions.

Further, the step 1 adopts an electromagnetic induction principle, a portable power supply, an inverter circuit and the primary coil are arranged outside the body, and the secondary coil, the power supply management and the artificial anal sphincter are implanted in the body.

Further, axial and radial uncertainty factors of the primary coil and the secondary coil are offset and deflection.

Further, the step 1 further includes calculating mutual inductance between the primary coil and the secondary coil, and establishing coordinates by taking a center point of the primary coil as an origin center, an axial direction as a y-axis, and a radial direction as an x-axis, wherein an axial distance between a center of the secondary coil and a center of the primary coil is h, a radial distance is r, and an included angle between the secondary coil and the primary coil is theta; the mutual inductance formula between the primary coil and the secondary coil is as follows:

wherein the content of the first and second substances,

mu is the magnetic permeability of the magnetic material,

and

radius of the ith primary and jth secondary coil, respectively, r is the lateral displacement, theta is the angular displacement between the coils, k is a variable, the parameter Ψ (k) is a function thereof,

for the integration angle of any point of the secondary coil, β, V, ξ are dimensionless parameters, k (k) and e (k) are full ellipse integrals of the first and second types, respectively.

Further, h, r, θ are bounded random variables, which are uncertain factors in the transcutaneous electrical energy transmission process, and the maximum coupling transmission efficiency in a full resonance state is as follows:

wherein α is a load factor, Q_P,Q_SAnd the no-load quality factors of the primary coil and the secondary coil are obtained.

Further, the heat conduction information of the secondary coil inside the human body includes a heat conduction coefficient of a complex environment near the anus.

Further, the step 2 further comprises the step of describing the heat dissipation condition of the secondary coil in the gastrointestinal tract by using a pennes heat transfer equation and considering the blood perfusion rate of the gastrointestinal tract tissue, wherein the heat dissipation power P is_rComprises the following steps: p_r＝K_TS₀τ, wherein K_TAs a material-dependent coefficient of heat dissipation, S₀Is the heat dissipation area, tau is the temperature difference with the ambient temperature; when the heating power of the secondary coil is not more than the heat dissipation capacity of the secondary coil, the secondary coil generates heat and does not damage human tissues.

Further, the step 3 may further include obtaining a boundary of the excitation frequency and the current corresponding to the given primary coil according to a human body electromagnetic dose threshold and a relationship between the human body electromagnetic dose threshold and the excitation frequency and the current.

Further, the calculation formula of the optimal parameter of the secondary winding under the condition corresponding to the step 4 is as follows:

Min{V}

wherein V is the secondary coil volume, f and I are the excitation frequency and the current, P_minTo account for the minimum power received at the time of the uncertainty factor, P₀The power required by the system, T is the real-time temperature of the secondary coil, T₀The upper limit of the temperature during long-term operation is usually 42.5⁰SAR is the local specific absorption rate and J is the current density.

Further, the step 4 may further include the following steps:

step 5, calculating the transmission power of the optimized secondary coil in a normal working state, and judging whether the minimum transmission power is greater than the preset power and whether the maximum transmission power meets the electromagnetic biological safety and temperature rise safety conditions;

step 6, if the conditions in the step 5 are met, taking the optimized parameters as conventional working information;

and 7, if the condition of the step 5 is not met, returning to the step 1.

The step 4 further comprises:

step 4.1, confirming the correlation with the minimum secondary coil volume which meets the constraint condition from the correlations;

and 4.2, adjusting the structural parameters of the secondary coil according to the mutual relation.

By the optimization design method, the robust stability boundary of power transmission is obtained based on the transcutaneous electric energy transmission model containing uncertain factors such as axial deviation, radial deviation and deflection, the safety threshold of the transcutaneous electric energy transmission system to human tissue cells under the sphincter muscle group environment is obtained based on the established human electromagnetic calculation model and the established biological heat transfer model, and the aim of improving the safety and the stability of the transcutaneous electric energy transmission system is fulfilled by optimizing the safety threshold.

And through the optimization design method, the working information of the upper limit of the transmission power of the secondary coil caused by the condition and the safety of the external portable power supply and the minimum transmission power requirement of the internal device is determined, and the optimization is carried out, so that the purposes of improving the space utilization rate of the secondary coil and the artificial anal sphincter and reducing the damage of the implanted device to the human body are achieved.

The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, the features and the effects of the present invention.

Drawings

Figure 1 is a schematic flow diagram of the present invention,

wherein S10-step 1, S20-step 2, S30-step 3, S40-step 4, S50-step 5, S60-step 6, S70-step 7;

FIG. 2 is a schematic diagram of a percutaneous electrical energy delivery system for an artificial anal sphincter;

FIG. 3 is a spatial coordinate diagram of the relative positions of the primary coil and the secondary coil;

fig. 4 is a schematic view of a secondary coil structure.

Detailed Description

The technical contents of the preferred embodiments of the present invention will be more clearly and easily understood by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

In the drawings, structurally identical elements are represented by like reference numerals, and structurally or functionally similar elements are represented by like reference numerals throughout the several views.

As shown in fig. 1, the invention provides a parameter optimization method for a secondary coil of a percutaneous electric energy transmission system facing an artificial anus, which is implemented by optimally designing parameters of the secondary coil of the percutaneous electric energy transmission system of the artificial anal sphincter, wherein an energy supply object is a water pump type artificial anal sphincter system, the load is 45 ohms on average, and the power consumption is 700 mW.

The secondary coil parameter optimization method of the percutaneous electric energy transmission system facing the artificial anus comprises 7 steps:

step 1(S10), a transcutaneous electric energy transmission model containing uncertain factors such as axial deviation, radial deviation and deflection is established based on the posture change of the human body and the position change condition of the primary and secondary side coils caused by other external factors.

The primary coil and the secondary coil are both composed of ferrite magnetic sheets and planar spiral litz wire windings, the primary coil is located outside the body, the size requirement is not strict, the secondary coil is implanted under the skin, and the outer diameter and the thickness of the secondary coil are required to be as small as possible. The axial spacing is 20 +/-5 mm, the radial spacing is +/-5 mm, and the angular deviation is +/-7.5 degrees.

Step 2(S20), establishing a corresponding in-vivo heat conduction model based on the heat conduction information of the secondary coil in the gastrointestinal tract of the human body;

the rated axial distance of the original secondary side is set to be 15mm, and at the moment, the secondary side coil is positioned at the subcutaneous fat part below the abdomen, so that the heat transfer environment is relatively single.

Step 3(S30), obtaining the correlation among the primary coil structure, the current, the driving frequency and the human body electromagnetic measurement based on the current density induced by the human body tissue in the electromagnetic environment and the absorption degree of the electromagnetic energy;

a finite element software is adopted to establish a human body electromagnetic calculation model to calculate the electromagnetic dose distribution of human body tissues in an electromagnetic field, wherein the SAR value is influenced by the electric field intensity, the electric conductivity and the tissue density and is in direct proportion to the driving frequency of an external electromagnetic field, and the J value is influenced by the electric field intensity and the electric conductivity and is in direct proportion to the magnitude and the frequency of primary side emission current.

Step 4(S40), considering the upper limit of transmission power caused by the condition and safety of the portable power supply in vitro and the requirement of the minimum transmission power of the in-vivo device, and obtaining the optimal parameters of the secondary coil under the corresponding conditions;

the optimized secondary side coil structure is shown in figure 4, and is wound by 30 turns of Litz wires obtained by 44AWG stranding, the secondary side coil has 2 layers, each layer has 13 turns, the outer diameter is 17.5mm, the inner diameter is 5.5mm, the single-layer inductance is 39.06 muH, and the resistance is 2.1 omega. The magnetic core has relative magnetic permeability of 2900, magnetic sheet thickness of 1mm, and electric conductivity of 0.25 (omega m) -1.

Preferably, after the step 4, the following steps are further included:

and 5(S50), calculating the transmission power of the optimized secondary coil in a normal working state, and judging whether the minimum transmission power is greater than the preset power and whether the maximum transmission power meets the electromagnetic biological safety and temperature rise safety conditions.

When the current frequency on the primary coil is 270KHz and the magnitude is 900mA, the power of more than 700mW can be continuously provided for the artificial sphincter, and in the most extreme case, the SAR value is 16.1mW/kg at most and is less than the minimum basic limit value of 0.4W/kg set by ICNIRP, the J value is 2.14A/m2 at most and is less than the minimum basic limit value of 10A/m2 set by ICNIRP, and meanwhile, the temperature of the secondary coil does not exceed the limit value. These parameters can be used as normal operating information. This design outperforms the prior results at the same size, with a reduction in volume of over 36% while meeting the power requirements of the system.

And 6(S60), if the condition is met, taking the optimized parameters as normal work information.

And 7, step 70, if the condition is not satisfied, returning to step 1.

As shown in fig. 2, which is a schematic structural diagram of a percutaneous electric energy transmission system of the artificial anal sphincter, the portable power supply, the inverter circuit and the primary coil are arranged outside the body, and the secondary coil, the power supply management and the artificial anal sphincter are implanted in the body.

As shown in fig. 3, the graph is a spatial coordinate diagram of relative positions of a primary coil and a secondary coil, a midpoint of the primary coil is an original center, an axial direction is a y-axis, and a radial direction is an x-axis to establish coordinates, wherein an axial distance between a center of the secondary coil and a center of the primary coil is h, a radial distance is r, and an included angle between the secondary coil and the primary coil is θ.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.