A neurostimulator and a receiving coil

Abstract

The present application provides a neurostimulator and a receiving coil. The neurostimulator includes a receiving coil and a resonant capacitor. The receiving coil receives wireless power from the transmitting coil and has an adjustable inductance. The resonant capacitor is electrically connected to the receiving coil and forms a resonant network with an adjustable resonant frequency with the receiving coil. The resonant network adjusts the efficiency of the receiving coil in receiving wireless power through the adjustable resonant frequency. The receiving coil includes a coil body and a magnetically adjustable structure provided on the coil body. The inductance of the magnetically adjustable structure changes in response to changes in ambient temperature and is negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature. When the ambient temperature rises to the over-temperature protection temperature, the inductance of the magnetically adjustable structure decreases to below the target inductance value. When the ambient temperature decreases below the rated operating temperature, the inductance of the magnetically adjustable structure remains constant at the rated inductance value.

Description

Technical Field

[0001] The present application relates to the technical field of stimulators, and in particular to a neural stimulator and a receiving coil. Background Art

[0002] A neurostimulator is a device used to deliver electrical signals to specific nerve regions. Its primary goal is to achieve therapeutic effects by modulating the electrical activity of neurons. Because a neurostimulator is surgically implanted into human tissue and electrically stimulates muscle or nerve tissue as needed, it must be as small as possible to minimize surgical risks.

[0003] A common solution is to simplify the energy storage unit and communication unit inside the neurostimulator by wirelessly powering and communicating the neurostimulator, thereby reducing the size of the neurostimulator.

[0004] However, this solution also brings new technical problems, namely that the electrical energy received by the neurostimulator is unstable. Since the distance between the neurostimulator and the programmer, the degree of alignment, and the current load of the neurostimulator may change, it is very likely that the neurostimulator will receive too much electrical energy within a certain time window, causing heat. In pursuit of miniaturization, the neurostimulator itself usually has a small overall specific heat capacity and heats up quickly, which can easily cause overheating of nearby tissues and cause damage. Summary of the Invention

[0005] In view of this, the present application provides a neurostimulator and a receiving coil.

[0006] Specifically, this application is implemented through the following technical solutions:

[0007] According to a first aspect of an embodiment of this specification, a neurostimulator is provided, which includes a receiving coil and a resonant capacitor, wherein the receiving coil is used to receive wireless power from a transmitting coil and the inductance of the receiving coil is adjustable, the resonant capacitor is electrically connected to the receiving coil and forms a resonant network with an adjustable resonant frequency with the receiving coil, and the resonant network adjusts the receiving efficiency of the receiving coil for the wireless power through the adjustable resonant frequency, wherein the receiving coil includes: a coil body; a magnetically adjustable structure, the magnetically adjustable structure is provided on the coil body and the inductance of the magnetically adjustable structure changes in response to changes in ambient temperature, the inductance is negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature, and when the ambient temperature rises to a preset over-temperature protection temperature, the inductance of the magnetically adjustable structure decreases to below a target inductance value; when the ambient temperature decreases to below the rated operating temperature, the inductance of the magnetically adjustable structure remains constant at the rated inductance value, and the target inductance value is the minimum inductance value corresponding to the over-temperature protection temperature.

[0008] According to a second aspect of the embodiments of this specification, a receiving coil and a neurostimulator are provided, wherein the receiving coil comprises: a coil body; a magnetically adjustable structure, wherein the magnetically adjustable structure is provided on the coil body and the inductance value of the magnetically adjustable structure changes in response to changes in ambient temperature, wherein the inductance value is negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature, and when the ambient temperature rises to a preset over-temperature protection temperature, the inductance value of the magnetically adjustable structure decreases to below a target inductance value; when the ambient temperature decreases to below the rated operating temperature, the inductance value of the magnetically adjustable structure remains constant at the rated inductance value, and the target inductance value is the minimum inductance value corresponding to the over-temperature protection temperature.

[0009] In the technical solution of the present application, the structure of the receiving coil of the neurostimulator is improved, and a magnetically adjustable structure is set on the body of the receiving coil. By utilizing the sensitivity of the magnetically adjustable structure to temperature, without adding a temperature sensor or other related circuit modules, the receiving coil itself can quickly respond to changes in ambient temperature to achieve automatic adjustment of its own inductance value only through its own structural characteristics. When the ambient temperature gradually increases from the rated operating temperature to the over-temperature protection temperature, the inductance value of the receiving coil will decrease significantly, causing the resonant frequency to deviate significantly from the transmitting frequency. When the ambient temperature gradually returns to the rated operating temperature, the inductance value of the magnetically adjustable structure returns to the low rated inductance value, causing the resonant network to operate at the transmitting frequency. In this way, when the ambient temperature rises above the over-temperature protection temperature, , the radio energy received by the receiving coil is significantly reduced, which can prevent the temperature of the surrounding tissue from further increasing and avoid damaging human tissue. In the process of the radio energy received by the receiving coil gradually decreasing, when the ambient temperature gradually returns to the rated operating temperature, the receiving efficiency of the receiving coil for radio energy reaches the maximum value, and the receiving coil normally supplies power to the load to be powered of the neurostimulator; when the ambient temperature drops below the rated operating temperature, the inductance value of the magnetically adjustable structure does not increase further but remains constant at the rated inductance value. When the rated operating temperature is higher than the lower limit of the normal operating temperature, the resonant network continues to operate at the transmitting frequency without significant deviation, ensuring that the receiving coil can still continue to supply power to the load to be powered of the neurostimulator normally in a low temperature environment.

[0010] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory and do not limit the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of a scenario of interaction between a neurostimulator and a programmer according to an exemplary embodiment of this specification;

[0012] Figure 2is a structural schematic diagram of a neurostimulator according to an exemplary embodiment of this specification;

[0013] Figure 3 is a structural diagram of a receiving coil according to an exemplary embodiment of this specification;

[0014] Figure 4 This specification is about an exemplary embodiment shown in Figure 3 Schematic diagram of the change of inductance value of the magnetically adjustable structure shown;

[0015] Figure 5 is a structural schematic diagram of a magnetically adjustable structure according to an exemplary embodiment of this specification;

[0016] Figure 6 This specification is about an exemplary embodiment shown in Figure 5 Schematic diagram of the change of inductance value of the magnetically adjustable structure shown;

[0017] Figure 7 This is a schematic diagram of partitioning of a receiving coil according to an exemplary embodiment of this specification. DETAILED DESCRIPTION

[0018] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with certain aspects of the present application.

[0019] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0020] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0021] like Figure 1As shown, a neurostimulator 110 is implanted in a patient by a physician and includes electrodes and a pulse generator. The electrodes are placed near the target nerve, and the pulse generator generates electrical stimulation pulses to the target nerve. The programmer 120 includes, but is not limited to, providing power to the neurostimulator 110, controlling and adjusting the parameters of the neurostimulator 110, and transmitting data to and from the neurostimulator 110. The programmer 120 can generally refer to any electronic device that has the aforementioned functions. Neurostimulators 110 include, but are not limited to, spinal cord stimulators (SCS), peripheral nerve stimulators (PNS), and tibial nerve stimulators (TNS).

[0022] The neurostimulator 110 is equipped with a receiving coil, and the programmer 120 is equipped with a transmitting coil. When the programmer 120 wirelessly powers the neurostimulator 110, the programmer 120 continuously transmits wireless energy through the transmitting coil, and the receiving coil couples and receives the wireless energy to power the neurostimulator 110.

[0023] As mentioned above, since the distance and alignment between the neurostimulator 110 and the programmer 120 and the current load of the neurostimulator 110 may change, it is very likely that the input power of the neurostimulator 110 will be too large. In this way, within a certain time window, the neurostimulator 110 will cause heat to be generated due to excessive electrical energy received, causing harm to the human body.

[0024] To address this issue, related technologies integrate a temperature sensor within the neurostimulator 110. This sensor senses the ambient temperature in real time and stops power supply when the ambient temperature is abnormal. For example, when the ambient temperature is abnormal, the neurostimulator 110 provides feedback to the programmer 120, causing the programmer 120 to stop wireless power output. Alternatively, a switching circuit is integrated within the neurostimulator 110. When the temperature sensor detects an abnormal ambient temperature, the switching circuit disconnects the power path to the neurostimulator 110.

[0025] However, integrating a temperature sensor inside the neurostimulator will cause the relevant technology to be inconsistent with the application requirements of miniaturization of the neurostimulator. In addition, the power supply control strategy based on the programmer has a long response time, and the excessive electrical energy continuously received during the response period can easily cause harm to the human body. Although the power supply control strategy based on the switching circuit has a faster response speed, it also requires the integration of the switching circuit in the neurostimulator, which will further increase the size of the neurostimulator.

[0026] Based on this, this solution improves the structure of the receiving coil of the neurostimulator. By configuring the inductance value of the receiving coil to have temperature response characteristics, it can quickly respond to ambient temperature changes without significantly increasing the volume of the neurostimulator, thereby realizing the over-temperature protection function of the neurostimulator.

[0027] To facilitate understanding of the following embodiments of this specification, the relevant technologies are first described in detail.

[0028] Soft magnetic materials, when magnetized at Hc no greater than 1000 A / m, are characterized by low coercivity and high permeability. Factors that affect the performance of soft magnetic materials include low temperatures, humidity, electromagnetic fields, mechanical loads, and ionizing radiation. Under these influences, basic properties of soft magnetic materials, such as permeability, can change.

[0029] A curing material is one that transforms from a liquid or semi-liquid state (such as a paste or gel) into a solid state through a physical or chemical process, forming a stable structure. Its core principle is to use energy (such as heat or ultraviolet light), chemical reactions, or time to irreversibly change the material's internal structure, ultimately achieving specific mechanical properties, weather resistance, or functionality. In this embodiment, the curing material is temperature-sensitive, expanding and contracting with heat and cooling. It also possesses a sufficient elastic modulus and thermal expansion coefficient to generate sufficient compressive force after thermal expansion deformation caused by rising ambient temperature.

[0030] Normal operating temperature: The neurostimulator can operate stably and normally for a long time within this temperature range without causing a significant increase in local tissue temperature due to self-heating. For example, the normal operating temperature of the neurostimulator is set to 35.0°C-38.9°C.

[0031] Rated operating temperature T op , the wireless power supply efficiency of the neurostimulator reaches the best performance at this temperature. For example, the rated operating temperature of the neurostimulator is set to 37.0°C. Generally, the rated operating temperature is higher than the lower limit of the normal operating temperature range T low .

[0032] Maximum tolerance temperature T max , the insurmountable limit of the temperature of the neurostimulator or human tissue. Exceeding this temperature may cause irreversible consequences, such as device damage, local tissue burns, etc. For example, the maximum tolerance temperature of the neurostimulator is set to 41.0°C.

[0033] Over temperature protection temperature T OTP When the temperature of the neurostimulator or surrounding tissue reaches this threshold, the protection mechanism is triggered, which significantly reduces the efficiency of wireless energy reception to prevent the ambient temperature from rising further. The over-temperature protection temperature of the neurostimulator should be greater than the rated operating temperature and less than the maximum tolerance temperature. For example, the over-temperature protection temperature of the neurostimulator is set to 39.0°C.

[0034] Over-temperature protection trigger temperature Ta, T low <Ta<T OTP , through this threshold and the over-temperature protection temperature TOTP , to achieve a step-by-step reduction in wireless energy receiving efficiency. When the temperature of the neurostimulator or surrounding tissue is at the lower limit of the normal operating temperature range T low When the temperature of the neurostimulator or surrounding tissue exceeds this threshold, the wireless energy receiving efficiency is constant at the rated receiving efficiency. When the temperature of the neurostimulator or surrounding tissue exceeds this threshold, the wireless energy receiving efficiency is significantly reduced. When the temperature of the neurostimulator or surrounding tissue reaches the over-temperature protection temperature T OTP When the wireless power is received, the efficiency of receiving wireless power is further significantly reduced.

[0035] Over-temperature protection function: when the temperature of the neurostimulator or surrounding tissue rises to the over-temperature protection temperature, the receiving efficiency of the receiving coil for wireless energy is reduced to a preset value. If the rated receiving efficiency of the receiving coil for wireless energy at the rated operating temperature is η , when the over-temperature protection is triggered, for example, the efficiency of the receiving coil in receiving wireless energy drops to 1 / 8 η the following.

[0036] Next, the embodiments of this specification are described in detail.

[0037] An embodiment of the present application provides a neurostimulator. Figure 2 This is a schematic diagram of the structure of a neurostimulator according to an exemplary embodiment of the present specification. Figure 2 As shown, in this embodiment, the neurostimulator includes a receiving coil 210 and a resonant capacitor 220. The receiving coil 210 is used to receive wireless power from the transmitting coil and the inductance value of the receiving coil 210 is adjustable. The resonant capacitor 220 is electrically connected to the receiving coil 210 and forms a resonant network with an adjustable resonant frequency with the receiving coil 210. The resonant network adjusts the receiving efficiency of the receiving coil 210 for wireless power through the adjustable resonant frequency, so that when the ambient temperature rises to the over-temperature protection temperature, the receiving efficiency of the receiving coil is significantly reduced to prevent the ambient temperature from further rising. When the ambient temperature returns to the rated operating temperature, the receiving coil receives wireless power at the maximum receiving efficiency to normally supply power to the load to be powered.

[0038] In this embodiment, the input end of the resonant capacitor 220 is electrically connected to the receiving coil 210, and the output end of the resonant capacitor 220 forms a port of the resonant network and is electrically connected to the load 230 to be powered by the neurostimulator. The load 230 to be powered includes functional modules such as the pulse generator and electrodes of the neurostimulator. The resonant frequency of the resonant network is f It can be calculated by the following formula:

[0039] (1)

[0040] In formula (1), C is the capacitance of the resonant capacitor, according to the inductance L at the rated operating temperature and the rated receiving frequency f 0 can calculate the capacitance value C. Rated receiving frequency f 0 is the same as the transmitting coil's transmitting frequency for wireless energy. f 0 provides wireless power, and when the resonant network operates at the rated receiving frequency, the receiving coil 210 achieves the highest efficiency in receiving wireless power. That is, the receiving coil's receiving efficiency is related to the degree of deviation from the resonant frequency. The further the resonant frequency deviates from the transmitting frequency, the lower the receiving coil's efficiency in receiving wireless power. The lower the deviation from the transmitting frequency, the higher the receiving coil's efficiency in receiving wireless power.

[0041] In this embodiment, C is a fixed value, and its value does not change due to changes in related parameters. The inductance value L of the receiving coil 210 is a dynamically changing value. At the rated operating temperature, the inductance value L of the receiving coil is a fixed value. When the ambient temperature changes, for example, when the ambient temperature rises to the over-temperature protection temperature, the inductance value of the receiving coil decreases. When the ambient temperature returns to the rated operating temperature, the inductance value of the receiving coil returns to the above-mentioned fixed value. In this way, the inductance value of the receiving coil 210 has a temperature response characteristic, and changes in the ambient temperature of the neurostimulator can trigger the receiving coil 210 to automatically adjust its inductance value. Among them, the "ambient temperature" described in this embodiment can be understood as the temperature of the neurostimulator itself or the temperature of human tissue near the neurostimulator.

[0042] like Figure 2 As shown, the receiving coil in this embodiment includes a coil body and a magnetically adjustable structure.

[0043] The coil body may be a planar metal coil, a spiral metal coil, etc. Those skilled in the art may flexibly set the shape of the coil body, and this embodiment does not impose any particular limitation on this.

[0044] A magnetically adjustable structure is provided on the coil body and the inductance value of the magnetically adjustable structure changes in response to changes in the ambient temperature. The inductance value is negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature. When the ambient temperature rises to a preset over-temperature protection temperature, the inductance value of the magnetically adjustable structure decreases to below a target inductance value. When the ambient temperature decreases to below the rated operating temperature, the inductance value of the magnetically adjustable structure remains constant at the rated inductance value. The target inductance value is the minimum inductance value corresponding to the over-temperature protection temperature.

[0045] Since the receiving coil 210 is provided with a magnetically adjustable structure, the inductance L of the receiving coil 210 can be calculated using the following formula:

[0046] L = L0 + ΔL (2)

[0047] ΔL∝ μ *A (3)

[0048] In formula (2), L0 is the inductance of the coil body, and ΔL is the inductance of the magnetically adjustable structure. Since the inductance of the magnetically adjustable structure is adjustable and changes automatically in response to changes in ambient temperature, the inductance of the receiving coil can be adjusted automatically without the need to set up an inductance adjustment circuit.

[0049] like Figure 4 As shown, from the rated operating temperature Top to the over-temperature protection temperature T OTP In the temperature range, the inductance value ΔL of the magnetic adjustable structure is negatively correlated with the ambient temperature. The increase of ambient temperature causes ΔL to decrease and when the ambient temperature rises to the over-temperature protection temperature T OTP When ΔL falls below the target inductance ΔLset, the receiving coil inductance L also decreases significantly. Consequently, when the receiving coil receives excessive power, causing the ambient temperature to rise to the over-temperature protection threshold, the deviation of the resonant frequency from the transmit frequency increases as the receiving coil inductance decreases, gradually reducing the receiving coil's efficiency in receiving wireless power. When the ambient temperature rises above the over-temperature protection threshold, the amount of wireless power received by the receiving coil decreases significantly, preventing further increases in the surrounding tissue temperature and potentially damaging human tissue.

[0050] When the ambient temperature drops, causing ΔL to increase, and when the ambient temperature drops to the rated operating temperature Top, the inductance of the magnetically adjustable structure ΔL increases to ΔLop. This allows the ambient temperature to gradually return to the rated operating temperature as the amount of wireless energy received by the receiving coil decreases. When the ambient temperature returns to the rated operating temperature, the inductance of the receiving coil also returns to its value at the rated operating temperature. At this point, the resonant network operates at the transmit frequency, the receiving coil reaches its maximum efficiency in receiving wireless energy, and the receiving coil begins to normally power the neurostimulator's load.

[0051] In some cases, the ambient temperature may be lower than the rated operating temperature. At this time, the inductance value of the magnetically adjustable structure will not increase further but will remain approximately constant at the rated inductance value, so that the resonant frequency will remain constant within the allowable error range of the transmitting frequency without significant deviation, ensuring that the receiving coil can still continue to supply power to the load to be powered of the neurostimulator in the low temperature range of the normal operating temperature range.

[0052] It can be seen from the above embodiments that by improving the structure of the receiving coil of the neurostimulator, a magnetically adjustable structure is provided on the body of the receiving coil, and the sensitivity of the magnetically adjustable structure to temperature is utilized. Without adding a temperature sensor or other related circuit modules, the receiving coil can quickly respond to changes in ambient temperature and automatically adjust its own inductance value only through its own structural characteristics. The deviation degree of the resonant frequency relative to the transmitting frequency is controlled by the change in the inductance value, thereby automatically reducing the reception efficiency of wireless energy when the temperature rises, realizing the over-temperature protection function of the neurostimulator, and automatically restoring the reception efficiency of wireless energy when the temperature drops, thereby providing normal power to the neurostimulator.

[0053] In one illustrated embodiment, Figure 3 As shown, the magnetically adjustable structure includes a magnetic core layer and a deformable layer. The inductance of the magnetically adjustable structure is positively correlated with the inductance of the magnetic core layer. The deformable layer fully covers the surface of the magnetic core layer. The deformable layer undergoes thermal expansion deformation in response to an increase in ambient temperature and thermal contraction deformation in response to a decrease in ambient temperature. Here, the increase and decrease in ambient temperature are both relative to the rated temperature. When the ambient temperature increases from the rated operating temperature, the deformable layer undergoes thermal expansion deformation; and when the ambient temperature decreases from the rated operating temperature, the deformable layer undergoes thermal contraction deformation.

[0054] The inductance of the core layer is positively correlated with the extrusion stress of the core layer. When the ambient temperature is higher than the over-temperature protection temperature, the extrusion stress caused by thermal expansion deformation causes the inductance of the core layer to drop below the target inductance value. When the ambient temperature drops below the rated operating temperature, the thermal contraction deformation stress causes the change in the inductance of the core layer to be less than the set change.

[0055] The relationship between the inductance of the magnetically adjustable structure and the parameters of the magnetic core layer is shown in formula (3):

[0056] ΔL∝μ*A (3)

[0057] In formula (3), “∝” is a positive correlation symbol, μ is the magnetic permeability of the core layer, and A is the bonding area of ​​the core layer.

[0058] The deformable layer fully covers the core layer to form the outer surface of the core layer. In this way, the deformable layer forms a physically closed space that completely covers the core layer. When the deformable layer expands and contracts due to heat, compressive stress or tensile stress can be formed on the surface of the core layer.

[0059] At the rated operating temperature, the interface stress between the core layer and the deformation layer is close to 0. When the ambient temperature rises, the deformation layer undergoes thermal expansion deformation. When the thermal expansion deformation reaches a certain extent, the thermal expansion deformation forms an extrusion stress acting on the core layer. The magnetic domain reversal resistance of the core layer increases due to the extrusion stress, resulting in an increase in the magnetic loss of the core layer and a decrease in the magnetic permeability. μ It can be seen from formula (3) that the magnetic permeability of the core layer μ The decrease will cause ΔL to decrease. It can be seen from formula (2) that as ΔL decreases, L will decrease.

[0060] When the ambient temperature drops to the rated operating temperature, the thermal expansion deformation of the deformation layer gradually decreases, and the extrusion stress on the core layer caused by the thermal expansion deformation also gradually decreases. Correspondingly, the magnetic domain reversal resistance of the core layer decreases, resulting in a decrease in the magnetic loss of the core layer and an increase in the magnetic permeability. μ Combining formulas (2)-(3), it can be seen that when the magnetic permeability of the core layer μ As it rises, L also rises.

[0061] When the ambient temperature drops below the rated operating temperature, the deformation layer undergoes thermal contraction deformation, which forms a tensile stress acting on the core layer. This tensile stress corresponds to the magnetic permeability of the core layer. μ The influence is low, the magnetic permeability μ The change in the inductance can be ignored. Therefore, when the ambient temperature drops below the rated operating temperature, the inductance value of the magnetically adjustable structure can be kept constant at the rated inductance value.

[0062] It should be noted that although magnetic materials are inherently temperature-sensitive, the rated operating temperature of a neurostimulator is 37°C, and the temperature difference between the neurostimulator's over-temperature protection temperature and its rated operating temperature is typically around 2°C. In this temperature environment, this small temperature difference has a minimal impact on the magnetic permeability of conventional magnetic materials. When the ambient temperature rises to the over-temperature protection temperature, the change in the receiving coil's inductance is minimal. In this case, the reduction in the receiving coil's efficiency in receiving wireless power is minimal, and the amount of received wireless power is not significantly reduced.

[0063] Based on this, this embodiment uses an indirect method to realize the correlation between the ambient temperature and the magnetic permeability of the core layer, which refers to the use of an intermediate strain to correlate the ambient temperature with the magnetic permeability of the core layer. Since the ambient temperature change can cause the deformation layer to expand and contract due to thermal expansion, the extrusion stress F formed by the thermal expansion phenomenon can be calculated by the following formula (4):

[0064] (4)

[0065] In the above formula (4), A is the bonding area of ​​the core layer, E is the elastic modulus of the deformation layer, is the thermal expansion coefficient of the deformation layer, is the ambient temperature change.

[0066] It can be seen from formula (4) that through special design, such as using a soft magnetic material with high sensitivity to stress to design the magnetic core layer, and using a solid material with a high elastic modulus and a large thermal expansion coefficient to design the deformable layer, the process of thermal expansion and contraction of the deformable layer will cause the stress load of the magnetic core layer to change significantly. When the stress load of the magnetic core layer changes significantly, the magnetic permeability of the magnetic core layer will also change accordingly.

[0067] Therefore, the deformation layer can convert relatively slight changes in ambient temperature into significant changes in strain force, which in turn causes a significant change in the magnetic permeability of the core layer. As a result, the inductance value of the receiving coil also indirectly has significant temperature sensitivity, and the neurostimulator can also realize its over-temperature protection function.

[0068] The magnetically adjustable structure of this embodiment, by designing a magnetic core layer and a deformation layer, uses the deformation layer to cover the entire surface of the magnetic core layer 360°, thereby constructing a temperature-strain-magnetic permeability coupling effect. When the ambient temperature changes slightly, the above-mentioned coupling effect can also cause a significant change in inductance. Therefore, without adding a temperature sensor or other related circuit modules, the receiving coil itself can quickly respond to slight changes in ambient temperature and achieve significant adjustment of its own inductance value only through the structural characteristics of the receiving coil itself.

[0069] In a possible implementation of this embodiment, the deformation layer is composed of a continuous medium without gaps or joints. Thus, by configuring the deformation layer as a uniform dielectric material without internal microscopic defects, the transmission efficiency of the thermally induced strain force can be improved.

[0070] In another possible implementation of this embodiment, the deformation layer is adhered to the surface of the magnetic core layer, and there are no bubbles, no delamination, and no gaps between the two layers of medium, thereby achieving a tight fit to avoid the interruption of strain force transmission caused by interface breakpoints and ensure that the thermally induced strain force is transmitted along the entire surface of the magnetic core layer.

[0071] Reference again Figure 3 , Figure 3The core layer shown is a dielectric layer without through holes inside. In this case, the deformation layer is tightly fitted to the core layer and covers the entire outer surface of the core layer. When the core layer is a hollow cylinder, the deformation layer is tightly fitted to the inner and outer surfaces of the core layer and completely covers the entire inner and outer surfaces of the core layer. The deformation layer portion covering the outer surface of the core layer and the deformation layer portion covering the inner surface of the core layer are continuous dielectric bodies, and there are no cracks, holes or splicing gaps between the two. Therefore, the deformation layer not only meets the requirements of geometric integrity but also material continuity. When the ambient temperature causes the deformation layer to undergo thermal deformation, since the deformation layer forms a closed coating structure in the form of a continuous dielectric and the deformation layer is tightly fitted to the core layer, the thermal deformation of the deformation layer can be effectively converted into strain acting on the core layer, causing the magnetic permeability of the core layer to change significantly.

[0072] like Figure 5 As shown, in one embodiment shown, the receiving coil further includes a thin film dielectric layer, the thin film dielectric layer fully covers the magnetic core layer, the deformable layer fully covers the thin film dielectric layer, and the inner surface of the thin film dielectric layer is in contact with the surface of the magnetic core layer, and the outer surface of the thin film dielectric layer is in contact with the inner surface of the deformable layer;

[0073] The thin film dielectric layer is used to isolate deformation stress at a specified temperature, where the specified temperature includes the rated operating temperature and / or the over-temperature protection trigger temperature. Specifically, the thin film dielectric layer is used to isolate extrusion stress below the over-temperature protection trigger temperature, and to isolate tensile stress below the rated operating temperature.

[0074] The thin film dielectric layer in this embodiment is a thin film material, and the elastic modulus of the thin film material is "much smaller" than the elastic modulus of the deformation layer material. Here, "much smaller" can be understood as being more than one order of magnitude smaller than the elastic modulus of the deformation layer material.

[0075] The thickness of the thin film dielectric layer is related to the volume and expansion coefficient of the deformation layer. When the ambient temperature reaches the over-temperature protection trigger temperature, the thermal expansion deformation of the deformation layer causes the elastic contraction of the thin film material to reach the proportional limit. Since the thin film material has a significant buffering effect on external stress before its proportional limit, the thin film material can be used to buffer the extrusion stress formed by the thermal expansion deformation of the deformation layer, thereby reducing the extrusion stress transmitted to the core layer. Figure 6As shown in the figure, when the ambient temperature is within the range of the rated operating temperature Top and the over-temperature protection trigger temperature Ta, the extrusion stress caused by thermal expansion deformation is buffered by the film material, and the extrusion stress transmitted to the core layer is small and can usually be ignored, so the change in magnetic permeability is small and approximately constant at the rated inductance value ΔLop; when the ambient temperature is higher than the over-temperature protection trigger temperature Ta, the elastic contraction of the film material exceeds the proportional limit. In this state, the buffering effect of the film material on the external stress is significantly reduced, and most of the newly added extrusion stress can be transmitted to the core layer, causing the magnetic permeability of the core layer to be significantly reduced under the action of external stress. When the ambient temperature reaches the over-temperature protection temperature T OTP When the inductance of the core layer is reduced to below ΔLset, it should be noted that the film material is OTP The elastic shrinkage is lower than the elastic limit of the film material.

[0076] It is worth noting that when the elastic shrinkage of the film material reaches the elastic limit, the film material will enter a plastic deformation state. After multiple thermal cycles, the film material may fail due to accumulated plastic deformation. Therefore, in practical applications, high-toughness materials such as rubber elastic media can be selected.

[0077] The smoothness of the outer surface of the thin film dielectric layer is positively correlated with its degree of isolation from tensile stress. The smoother the outer surface of the thin film dielectric layer, the stronger its isolation from tensile stress. Based on this, in this embodiment, the outer surface of the thin film dielectric layer can be designed to be smooth to isolate tensile stress below the rated operating temperature Top, reduce the effect of tensile stress on the magnetic permeability of the magnetic core layer, and ensure that the magnetic permeability of the magnetic core layer is constant at the rated permeability when the ambient temperature is lower than the rated operating temperature.

[0078] In one illustrated embodiment, again referring to Figure 5 The receiving coil also includes a peripheral dielectric layer, which covers the entire surface of the deformation layer to constrain the stress transfer direction of thermal expansion deformation.

[0079] In this embodiment, the elastic modulus of the peripheral dielectric layer is greater than the elastic modulus of the deformable layer. Thus, when the deformable layer undergoes thermal expansion deformation, the compressive stress generated by the thermal expansion deformation can be transferred toward the magnetic core layer through the constraint of the peripheral dielectric layer, thereby improving the transfer efficiency of the compressive stress.

[0080] In an illustrated embodiment, the dielectric material of the magnetic core layer includes a soft magnetic material whose magnetic permeability is highly sensitive to stress load. In practical applications, the soft magnetic material of the magnetic core layer includes manganese-zinc ferrite.

[0081] In one illustrated embodiment, the dielectric material of the deformable layer includes a solidified material. The deformable layer is cured through a heat treatment process to form a glassy dielectric layer. This embodiment can couple the deformable layer and the magnetic core layer through a heat treatment process. For example, a soft magnetic material is placed in a mold, and then the mold is filled with a liquid or semi-liquid solidified material. Once the solidified material is completely cured, the desired magnetically adjustable structure is obtained.

[0082] In an illustrated embodiment, the glass transition temperature of the solidified material is greater than the over-temperature protection temperature of the neurostimulator, so as to ensure that the solidified material remains in a glassy state when the ambient temperature is greater than the over-temperature protection temperature.

[0083] In one embodiment shown, the elastic modulus of the solidified material after solidification should be greater than the set elastic modulus value, and the thermal expansion coefficient should be greater than the set thermal expansion coefficient value. The magnetic permeability of the core layer is inversely proportional to the extrusion stress. When the extrusion stress increases, the magnetic permeability decreases. When the solidified material shrinks from the thermal expansion state to the normal state (i.e., the shape at normal operating temperature), the thermal expansion deformation gradually decreases, and the extrusion stress also decreases, resulting in an increase in the magnetic permeability. Referring again to formula (4), the extrusion stress is positively correlated with the elastic modulus and thermal expansion coefficient. Therefore, when a solidified material with a large elastic modulus and thermal expansion coefficient is selected to construct the deformable layer, the deformable layer can undergo thermal expansion and contraction when the ambient temperature changes slightly, and the thermal strain force formed is sufficiently large.

[0084] In one possible implementation of this embodiment, at the rated operating temperature, the interfacial stress between the solidified material and the soft magnetic material is less than a preset stress value, such that when the ambient temperature is the rated operating temperature, the inductance of the magnetically adjustable structure is the rated inductance value. The preset stress value here is a value close to 0. In practical applications, this preset stress value should be "much less" than the interfacial stress value at the over-temperature protection temperature. "Much less" here can be understood as being less than an order of magnitude or more from the interfacial stress value at the over-temperature protection temperature.

[0085] In an illustrated embodiment, the shape of the contact surface between the magnetically adjustable structure and the coil body is adapted to the geometric profile of the receiving coil.

[0086] For example, when the coil body is planar, the contact surface of the magnetically adjustable structure is flat; when the coil body is helical, the contact surface of the magnetically adjustable structure is curved. This minimizes the distance between the magnetic core layer and the coil body, thereby improving the efficiency of the receiving coil in receiving wireless power at the rated operating temperature.

[0087] In an illustrated embodiment, the magnetic core layer is located in a magnetic flux concentration region of the coil body for guiding or enhancing the magnetic flux of the coil body, wherein the magnetic flux concentration region can be understood as a region capable of increasing the magnetic flux of the coil.

[0088] In some possible implementations of this embodiment, the magnetic flux concentration region is located on the surface of the coil body facing away from the transmitting coil, or on the inner surface of the annular sidewall of the coil body. For example, when the coil body is a planar coil, the magnetic flux concentration region is located on the surface of the coil body facing away from the transmitting coil, while when the coil body is a spiral coil, the magnetic flux concentration region is located on the inner surface of the annular sidewall of the coil body.

[0089] In an illustrated embodiment, the receiving coil includes a communication area and a power supply area. The power supply area has a dedicated area different from the communication area, and the magnetically adjustable structure is disposed in the dedicated area.

[0090] In this embodiment, the receiving coil of the neurostimulator has both wireless communication and wireless power supply functions. Figure 7 As shown, the receiving coil is divided into a communication area and a power supply area, and a magnetically adjustable structure is set in the dedicated area. The change of the inductance value in the power supply area does not limit the flexibility of setting the inductance value of the communication coil.

[0091] Next, we will use the design process of the receiving coil as an example to illustrate the over-temperature protection function of the neurostimulator:

[0092] Assuming that the magnetically adjustable structure includes a magnetic core layer and a deformation layer, during wireless power supply, the over-temperature protection function requires that when the temperature reaches 39.0°C, the wireless power supply receiving efficiency drops to less than 1 / 8 of the efficiency at the rated operating temperature. The operating frequency of the wireless power supply is f =10MHz, the area of ​​the receiving coil is A1=10cm 2 , the inductance of the coil body is L0=10 u H, the bonding area of ​​the soft magnetic material is A2=5cm 2 , A2≤A1, after the soft magnetic material is coated with the solidified material and set on the coil body, at the rated operating temperature, the inductance value of the receiving coil is L=20 u H.

[0093] If the total resistance of the receiving coil and the load resistance of the neurostimulator is R1 = 100Ω, then the quality factor of the receiving coil at the rated operating temperature is Q = (2π f L) / R1=12.56, the corresponding -3dB bandwidth BW= f / Q≈800kHz, and the unilateral -3dB bandwidth is 1 / 2BW=400 kHz. Therefore, for every 400 kHz that the resonant frequency deviates from the rated operating frequency, the receiving efficiency is further attenuated by 50%. For example, if the real-time operating frequency deviates by 400 kHz relative to the rated operating frequency of 10MHz, the receiving efficiency is reduced by 1 / 2. If the real-time operating frequency deviates by 800 kHz relative to the rated operating frequency of 10MHz, the receiving efficiency is reduced by 1 / 4. If the real-time operating frequency deviates by 1200 kHz relative to the rated operating frequency of 10MHz, the receiving efficiency is reduced by 1 / 8.

[0094] Based on this, the capacitance value of the resonant capacitor at the rated operating temperature can be calculated. .

[0095] Assume that the elastic modulus of the cured material after curing is E=2GPa and the thermal expansion coefficient is =50ppm / ℃, when the ambient temperature changes from 37℃ to 39℃, the compressive stress applied to the soft magnetic material .

[0096] Under the action of the compressive stress F, the magnetic permeability of the soft magnetic material μ The inductance of the receiving coil becomes L'=18.5 u H, the corresponding resonant frequency becomes , the resonant frequency is compared to the operating frequency f The offset is about 400kHz, and the reception efficiency of wireless energy drops by 1 / 2, failing to meet the requirement of attenuation below 1 / 8. In this case, the attenuation degree of reception efficiency can be improved by at least one of the following methods:

[0097] 1) Increase the bonding area A2 of the soft magnetic material, or reduce the distance between the soft magnetic material and the receiving coil;

[0098] 2) Replace the soft magnetic material with higher magnetic permeability;

[0099] 3) Change the elastic modulus E and thermal expansion coefficient Higher curing materials;

[0100] When the attenuation degree of the receiving efficiency is improved by at least one of the above-mentioned methods, the modified attenuation degree of the receiving efficiency is calculated again through the above-mentioned steps until the attenuation requirement is met.

[0101] An embodiment of the present application further provides a receiving coil, which is applied to a neurostimulator. For the structure and function of the receiving coil in this embodiment, reference may be made to the above-mentioned related embodiments, which will not be described in detail in this embodiment.

[0102] Although this specification includes many specific implementation details, these should not be interpreted as limiting the scope of any invention or the scope of protection claimed, but are mainly used to describe the features of specific embodiments of specific inventions. Certain features described in multiple embodiments within this specification may also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although features may work in certain combinations as described above and even initially claimed as such, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may point to a sub-combination or a variation of the sub-combination.

[0103] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A neurostimulator, characterized in that: The invention comprises a receiving coil and a resonant capacitor, wherein the receiving coil is used to receive wireless power from the transmitting coil and the inductance of the receiving coil is adjustable. The resonant capacitor is electrically connected to the receiving coil and forms a resonant network with an adjustable resonant frequency with the receiving coil. The resonant network adjusts the efficiency of the receiving coil in receiving the wireless power through the adjustable resonant frequency. The receiving coil comprises: Coil body; A magnetically adjustable structure, wherein the magnetically adjustable structure is provided on the coil body and the inductance of the magnetically adjustable structure changes in response to changes in ambient temperature, the inductance being negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature, and the inductance of the magnetically adjustable structure decreases below a target inductance when the ambient temperature rises to a preset over-temperature protection temperature; when the ambient temperature decreases below the rated operating temperature, the inductance of the magnetically adjustable structure remains constant at the rated inductance, and the target inductance is the minimum inductance corresponding to the over-temperature protection temperature; The magnetically adjustable structure comprises: A magnetic core layer, wherein the inductance of the magnetically adjustable structure is positively correlated with the inductance of the magnetic core layer; a deformation layer, wherein the deformation layer covers the entire surface of the magnetic core layer, and the deformation layer undergoes thermal expansion deformation in response to an increase in the ambient temperature and thermal contraction deformation in response to a decrease in the ambient temperature; The inductance of the magnetic core layer is positively correlated with the compressive stress of the magnetic core layer, and when the ambient temperature is higher than the over-temperature protection temperature, the compressive stress formed by the thermal expansion deformation causes the inductance of the magnetic core layer to drop below the target inductance value; when the ambient temperature drops below the rated operating temperature, the thermal contraction deformation stress causes the change in the inductance of the magnetic core layer to be less than the set change.

2. The neurostimulator according to claim 1, wherein The deformable layer is composed of a continuous medium, and the inner surface of the deformable layer is in contact with the surface of the magnetic core layer.

3. The neurostimulator according to claim 1, wherein The receiving coil further includes a thin film dielectric layer, wherein the thin film dielectric layer fully covers the magnetic core layer, and the deformable layer fully covers the thin film dielectric layer, and the inner surface of the thin film dielectric layer is in contact with the surface of the magnetic core layer, and the outer surface of the thin film dielectric layer is in contact with the inner surface of the deformable layer; The thin film dielectric layer is used to isolate deformation stress at a specified temperature, where the specified temperature includes the rated operating temperature and / or an over-temperature protection trigger temperature, and the over-temperature protection trigger temperature is greater than the rated operating temperature and less than the over-temperature protection temperature.

4. The neurostimulator according to claim 1, wherein The receiving coil further includes a peripheral dielectric layer, which covers the entire surface of the deformable layer to constrain the stress transfer direction of the thermal expansion deformation.

5. The neurostimulator according to claim 1, wherein The dielectric material of the magnetic core layer includes a soft magnetic material, the dielectric material of the deformable layer includes a solidified material, and the deformable layer is solidified by a heat treatment process of the solidified material to form a glassy dielectric layer.

6. The neurostimulator according to claim 5, characterized in that At the rated operating temperature, the interface stress between the solidified material and the soft magnetic material is less than a preset stress value, so that when the ambient temperature is the rated operating temperature, the inductance value of the magnetically adjustable structure is the rated inductance value.

7. The neurostimulator according to claim 1, wherein The shape of the fitting surface between the adjustable magnetic structure and the coil body is adapted to the geometric profile of the receiving coil.

8. The neurostimulator according to claim 1, wherein The magnetic core layer is located in a magnetic flux concentration area of ​​the coil body. The magnetic flux concentration area is located on a surface of the coil body facing away from the transmitting coil, or on an inner surface of an annular side wall of the coil body.

9. The neurostimulator according to claim 1, wherein The receiving coil includes a communication area and a power supply area. The power supply area has a dedicated area different from the communication area. The magnetically adjustable structure is provided in the dedicated area.

10. A receiving coil, characterized in that: The receiving coil is applied to a neurostimulator, and the receiving coil includes: Coil body; A magnetically adjustable structure, wherein the magnetically adjustable structure is provided on the coil body and the inductance of the magnetically adjustable structure changes in response to changes in ambient temperature, the inductance being negatively correlated with the ambient temperature when the ambient temperature is higher than the rated operating temperature, and the inductance of the magnetically adjustable structure decreases below a target inductance when the ambient temperature rises to a preset over-temperature protection temperature; when the ambient temperature decreases below the rated operating temperature, the inductance of the magnetically adjustable structure remains constant at the rated inductance, and the target inductance is the minimum inductance corresponding to the over-temperature protection temperature; Wherein, the magnetically adjustable structure comprises: A magnetic core layer, wherein the inductance of the magnetically adjustable structure is positively correlated with the inductance of the magnetic core layer; a deformation layer, wherein the deformation layer covers the entire surface of the magnetic core layer, and the deformation layer undergoes thermal expansion deformation in response to an increase in the ambient temperature and thermal contraction deformation in response to a decrease in the ambient temperature; The inductance of the magnetic core layer is positively correlated with the compressive stress of the magnetic core layer, and when the ambient temperature is higher than the over-temperature protection temperature, the compressive stress formed by the thermal expansion deformation causes the inductance of the magnetic core layer to decrease below the target inductance value; when the ambient temperature decreases below the rated operating temperature, the thermal contraction deformation stress causes the change in the inductance of the magnetic core layer to be less than the set change.

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