Implants, brain-machine interface systems, methods of manufacture

Abstract

The present application belongs to the technical field of physiological electrical signal, and particularly relates to an implant, a brain-computer interface system and a preparation method, which physically abandons the direct short-circuiting scheme of the traditional internal circuit reference ground and the shell, and presents the open-circuit high-impedance characteristics under the direct current working condition through the capacitor structure formed by the coupling conductor, the insulating medium and the first conductive layer on the inner surface of the shell, thereby blocking the conduction of the dangerous direct current to the external shell and the external physiological environment; meanwhile, the low-impedance alternating current coupling characteristics of the capacitor structure under the high-frequency radio frequency are utilized, so that the external shell becomes a high-efficiency radio frequency return ground net under the antenna working frequency, thereby providing a wide electromagnetic reflection surface for the internal antenna and solving the problem of extremely low antenna radiation efficiency in the closed cavity.

Description

Technical Field

[0001] This invention belongs to the field of physiological electrical signal technology, specifically relating to an implant, a brain-computer interface system, and a preparation method. Background Technology

[0002] With the rapid development of neural engineering and active implantable medical devices (such as implantable brain-computer interfaces and pacemakers), the demand for high-speed wireless data interaction between the implant and the external device is increasing. Due to the extremely limited space at the implantation site, the design of implantable antennas has consistently focused on miniaturization. Existing antenna miniaturization solutions often emphasize constructing a highly compact radiating structure within the device. For example, CN115149251A discloses a miniaturized implantable medical antenna and a miniaturized implantable medical device, which uses a first radiator and a second radiator to form the antenna, both of which are bent metal sheets. The first radiator is connected to the feed point of the circuit board, and the second radiator is directly connected to the system ground of the circuit board. A variable capacitor is placed between the two radiators, thereby achieving resonant frequency adjustment and physical size reduction within a very small volume.

[0003] While the aforementioned internal miniaturization design can alleviate the space occupation issue to some extent, in actual clinical applications, due to the extremely compressed physical area of ​​the internal radiator and reference ground, the antenna's radiation efficiency typically decreases significantly when it needs to penetrate high-loss human tissue for communication. This makes it difficult to meet the high-bandwidth, low-latency communication requirements of multi-channel devices such as brain-computer interfaces. Furthermore, due to the complex electromagnetic boundary conditions of the human body (such as tissue fluid infiltration and tissue proliferation), antennas in such confined spaces are highly susceptible to resonant frequency drift, leading to detuning.

[0004] On the other hand, according to mandatory safety standards for medical electrical equipment, such as "Medical electrical equipment - Part 1: General requirements for basic safety and essential performance" (GB 9706.1-2020) and the International Electrotechnical Commission standard "Medical electrical equipment - Part 1: General requirements for basic safety and essential performance" (IEC 60601-1:2005), active implantable medical devices have extremely strict leakage current insulation protection limits under both normal and single-fault conditions. However, the traditional physical insulation design between the reference ground and the external housing used to meet this safety standard results in extremely low overall radiation efficiency of the miniaturized antenna system inside the implant due to the lack of a stable and large electromagnetic return and reflection reference surface within the highly enclosed housing.

[0005] Therefore, under the premise of strictly meeting the aforementioned national and international clinical safety standards for leakage current isolation, how to significantly improve the radio frequency radiation efficiency of the antenna system within the extremely limited implantation space is a technical problem that urgently needs to be solved in the field of active implantable medical communication. Summary of the Invention

[0006] This invention provides an implant, a brain-computer interface system, and a preparation method.

[0007] To address the aforementioned technical problems, the present invention provides an implant comprising: a housing, which is internally enclosed and contains a circuit, wherein a first conductive layer is provided on the inner surface of the housing; an antenna disposed on the outside of the housing and electrically connected to the circuit inside the housing via an insulating feedthrough; and a coupling conductor housed inside the housing and connected to a reference ground of the circuit, wherein the coupling conductor is disposed opposite to the first conductive layer and an insulating medium is sandwiched between them, such that the coupling conductor, the insulating medium, and the first conductive layer constitute a capacitor structure; under DC operating conditions, the capacitor structure is in a DC open-circuit state to block DC current conducted to the first conductive layer; and at the antenna operating frequency, the capacitor structure achieves AC coupling, making the first conductive layer the radio frequency return ground of the antenna.

[0008] Furthermore, the interior of the housing contains a circuit carrier; the coupling conductor is a second conductive layer disposed on the circuit carrier; and the second conductive layer, the insulating medium, and the first conductive layer are arranged in a conformal stacked or parallel adjacent arrangement.

[0009] Furthermore, the upper surface of the second conductive layer is disposed opposite to the first conductive layer at the top of the housing and is isolated by an insulating medium to form a first capacitor; the lower surface of the second conductive layer is disposed opposite to the first conductive layer at the bottom of the housing and is isolated by an insulating medium to form a second capacitor; and the first capacitor and the second capacitor are connected in parallel to form the capacitor structure.

[0010] Furthermore, the implant also includes a positioning structure for defining the position of the circuit carrier inside the housing; the positioning structure is configured to: adjust the spacing between the upper and lower surfaces of the second conductive layer and the first conductive layer, so that the total equivalent capacitance of the capacitor structure at the antenna operating frequency is not less than the lower limit of capacitance, and / or so that the leakage current of the capacitor structure under DC conditions is not greater than the upper limit of current.

[0011] Furthermore, at the antenna operating frequency, the constraint relationship between the lower limit of the capacitance and the spacing is C. ;in This represents the absolute dielectric constant of the insulating medium in the first capacitor. This represents the absolute dielectric constant of the insulating medium in the second capacitor. This indicates the distance between the relative plates in the first capacitor. The distance between the relative plates in the second capacitor is represented by S, the overlapping projected area of ​​the second conductive layer and the first conductive layer is represented by C, and the capacitance value of the capacitor structure is represented by C. This indicates the capacitance value of the first capacitor. This indicates the capacitance value of the second capacitor. This indicates the lower limit of capacitance for the capacitor structure.

[0012] Furthermore, under DC operating conditions, the constraint relationship between the upper limit of the leakage current and the spacing is as follows: ;in, This represents the volume resistivity of the insulating medium in the first capacitor; This represents the volume resistivity of the insulating dielectric in the second capacitor. This indicates the distance between the relative plates in the first capacitor. The distance between the relative plates in the second capacitor is represented by S, the overlapping projected area of ​​the second conductive layer and the first conductive layer is represented by U, and the maximum operating voltage of the system is represented by U. This indicates the upper limit of leakage current of the capacitor structure. This represents the leakage current detected through the capacitor structure.

[0013] Furthermore, the circuit carrier is a circuit board, and the second conductive layer is a grounded copper layer disposed on the surface or inner layer of the circuit board.

[0014] Furthermore, the circuit includes a radio frequency (RF) circuit; the signal output terminal of the RF circuit is electrically connected to the antenna inside the housing, and the RF reference ground of the RF circuit is electrically connected to a coupling conductor inside the housing.

[0015] The present invention also provides a brain-computer interface system, comprising: the implant, configured to be implanted in a patient's body to process neural signals; and an external unit, disposed outside the patient's body and equipped with an external radio frequency transceiver circuit and an external antenna; wherein the operating frequency of the antenna is the radio frequency communication frequency for data interaction between the implant and the external unit; the DC operating condition includes the DC power supply state of the implant when processing neural signals or receiving wireless power from the external unit, or the fault state of DC leakage.

[0016] The present invention also provides a method for preparing the implant, comprising: determining a first spacing and a second spacing based on the constraint relationship between the lower limit of capacitance, the upper limit of leakage current, and the spacing of the capacitor structure; determining a target position of the circuit carrier inside the housing based on the first spacing and the second spacing; adjusting a positioning structure disposed inside the housing to position and fix the circuit carrier to the target position; wherein the first spacing represents the distance between the upper surface of the second conductive layer and the first conductive layer at the top of the housing; and the second spacing represents the distance between the lower surface of the second conductive layer and the first conductive layer at the bottom of the housing.

[0017] The beneficial effects of this invention are that the implant, brain-computer interface system, and manufacturing method of this invention physically abandon the traditional DC conduction scheme of directly short-circuiting the internal circuit reference ground to the outer shell. Through the capacitive structure formed in space by the coupling conductor, insulating medium, and the first conductive layer on the inner surface of the shell, it exhibits high impedance characteristics under DC conditions, blocking the conduction of dangerous DC current to the outer shell and the external physiological environment. At the same time, by utilizing the low impedance AC coupling characteristics of this capacitive structure under high-frequency radio frequency, the outer shell becomes an efficient radio frequency return ground network at the antenna operating frequency, providing a wide electromagnetic reflection surface for the internal antenna and solving the problem of extremely low antenna radiation efficiency in a closed cavity.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. To make the foregoing objects, features, and advantages of the invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the implant's structure.

[0021] Figure 2 This is a schematic diagram of the equivalent circuit for DC isolation and AC coupling of an implant.

[0022] In the diagram: housing-1, inner surface of housing / first conductive layer-11, circuit carrier / circuit board-2, coupling conductor / second conductive layer-3, insulating feedthrough-4, antenna-5, insulating medium-6, radio frequency circuit-7, signal output terminal-71, radio frequency reference ground-72, impedance matching network-8, capacitor structure-9, first capacitor-91, second capacitor-92. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Combination Figure 1 , Figure 2 As shown, in some preferred embodiments, an implant is provided suitable for active implantable medical devices such as brain-computer interfaces, pacemakers, or neurostimulators. The implant includes a housing 1, an antenna 5, a coupling conductor 3, and internal circuitry.

[0025] The housing 1 has an airtight sealed structure and houses a circuit carrier 2 inside. The circuit carrier 2 is equipped with the internal circuit, which includes a radio frequency circuit 7 and other operating circuits. The inner surface of the housing 1 is provided with a first conductive layer 11, and the outer surface is provided with a protective layer.

[0026] In practical assembly and application scenarios, the housing 1, the first conductive layer 11, and the protective layer can be implemented based on the following configurations to balance high-frequency grounding and external electrical insulation protection: In one configuration, the housing 1 is a one-piece molded metal housing (such as medical-grade pure titanium or Ti-6Al-4V titanium alloy). The inner wall of the housing 1 directly constitutes the first conductive layer 11. A protective layer is provided on the outer surface of the housing 1, which is a metal oxide ceramic insulating layer generated by surface anodizing. In another configuration, the housing is a non-metallic housing (such as zirconia ceramic, liquid crystal polymer LCP, or polyetheretherketone PEEK). The housing itself is non-conductive, and the first conductive layer is a conductive coating (such as a PVD titanium / gold layer) attached to the inner surface of the housing or a conductive component embedded inside the non-metallic housing and exposed on the inner surface. In this case, the protective layer is a biocompatible polymer electrically insulating film layer (such as a Parylene-C film) deposited on the outer surface of the non-metallic housing or the outer insulating solid wall of the non-metallic housing itself.

[0027] In this application, "system ground," "reference ground," and "system GND" have the same technical meaning, all referring to the zero-potential reference plane of the internal circuitry (including but not limited to radio frequency circuits, control circuits, etc.) of the implant. "Outer shell ground" refers to the conductive layer of the metal shell or inner wall of the implant. In the implanted state, the potential state of the "outer shell ground" directly affects the biosafety of the human body. "Radio frequency reference ground" refers to the equivalent ground network used to provide a high-frequency return path and ensure antenna radiation efficiency when the antenna transmits and receives high-frequency electromagnetic wave signals. It should be specifically noted that in the technical solution of this invention, the outer shell ground and the system ground are not physically directly shorted. This invention constructs an AC coupling path between the system ground and the outer shell ground by configuring a specific capacitor structure. Based on the inherent frequency response characteristics of this capacitor structure: in DC or low-frequency states, the outer shell ground and the system ground exhibit a high-impedance isolation state, thereby blocking DC leakage and meeting the safety standards for implantable medical devices; in the radio frequency operating band of the antenna, the outer shell ground and the system ground exhibit a low-impedance conduction state through the capacitor structure. In this way, the outer casing ground is effectively multiplexed as the "RF reference ground" of the antenna at high RF frequencies, greatly expanding the effective area of ​​the RF return ground network, thereby significantly improving the radiation efficiency of the antenna inside the enclosed metal cavity. This is a preferred embodiment for constructing a capacitively coupled ground network. The coupling conductor 3 is specifically a second conductive layer 3 disposed on the circuit carrier 2. This second conductive layer 3 is directly electrically connected to the reference ground (system ground) of the internal circuit, giving the circuit carrier a stable zero-potential reference surface. The second conductive layer 3 (i.e., the coupling conductor 3) and the first conductive layer 11 on the inner surface of the casing 1 are spatially adjacent, with an insulating medium 6 (such as one or more of a circuit board substrate, solder mask, insulating film, air gap, or potting material) sandwiched between them. Because the two are spatially adjacent, a three-dimensional distributed capacitor structure 9 is naturally formed within the coupling region by utilizing a large area of ​​opposing electric fields or edge electric field linkages. This structure achieves the following functions: Under DC conditions, the capacitor structure is in a DC open-circuit state to block DC current conducted to the first conductive layer; at the antenna operating frequency, the capacitor structure achieves AC coupling, making the first conductive layer the RF return ground network of the antenna. Here, "DC open-circuit state" means that the capacitor structure exhibits an equivalent impedance higher than a first preset threshold under DC conditions to block DC current (or keep leakage current within a safe range); "AC coupling" means that the capacitor structure exhibits an equivalent impedance lower than a second preset threshold at the antenna operating frequency to allow AC signals to pass through without loss or with low loss.

[0028] To adapt to the extremely limited implantation space, the circuit carrier 2 can adopt various physical forms: it can be a flexible circuit board (FPC), a rigid circuit board, or a rigid-flex board, with the second conductive layer 3 disposed on its surface or inner layer, specifically as a grounded copper layer. In this case, the second conductive layer 3, the insulating medium 6, and the first conductive layer 11 can conform to the curvature of the inner wall of the shell, arranged in a conformal stacked or parallel adjacent arrangement. In this case, the capacitor structure 9 includes a first capacitor 91 and a second capacitor 92 connected in parallel; wherein the first capacitor 91 includes the upper surface of the second conductive layer 3 and the inner surface 11 of the top of the shell 1 and the insulating medium 6 between them, and the second capacitor 92 includes the lower surface of the second conductive layer 3 and the inner surface 11 of the bottom of the shell 1 and the insulating medium 6 between them. Alternatively, it can be an internal structural support (such as a plastic support frame), with a metal layer plated as the second conductive layer using three-dimensional molding interconnect (3D-MID) technology; or it can be directly the metal shell of the internal metal shield or the internal battery, using its large outer surface as the second conductive layer to form a capacitor structure with the first conductive layer.

[0029] In the specific design process, the implant also includes a positioning structure for defining the position of the circuit carrier inside the housing; the positioning structure, for example but not limited to injection-molded silicone, maintains a preset first distance and / or second distance between the second conductive layer and the first conductive layer to meet the usage requirements of the capacitor structure 9.

[0030] Adjustment method one meets the minimum capacitance requirement at the antenna operating frequency.

[0031] At the antenna operating frequency, the lower limit of the equivalent total capacitance C of the capacitor structure is set to [value missing]. Then C .in Represents the vacuum permittivity. This represents the absolute dielectric constant of the insulating medium in the first capacitor. This represents the absolute dielectric constant of the insulating medium in the second capacitor. This represents the first distance between the plates in the first capacitor. This indicates the second distance between the plates in the second capacitor. This represents the projected area of ​​the overlap between the second conductive layer and the first conductive layer. This indicates the capacitance value of the first capacitor. This indicates the capacitance value of the second capacitor. It can be adjusted during the design verification phase. , , , , Make the total capacity C Preferably using an insulating medium with a high dielectric constant, so that... This adjustment , , To ensure C During the mass production assembly stage, adjustments were made... , make .

[0032] Optionally, the minimum limit is This can be obtained by setting the antenna impedance Z, and the rate of change of the antenna impedance setting. ,but Z ;in For imaginary numbers, This refers to the angular frequency of the antenna's operating band. For example, a common antenna impedance Z is 50Ω. If the first conductive layer is required to function as a ground plane, then the antenna impedance change rate... Less than 10%, therefore the capacitive reactance of the capacitance structure between the first and second conductive layers at the antenna operating frequency is less than 5Ω, i.e. A minimum value can be determined using this formula. .

[0033] Adjustment method two meets the requirement of the maximum current limit under DC operating conditions.

[0034] Under DC operating conditions, the maximum operating voltage U of the system is set, and the upper limit of the leakage current flowing through the capacitor structure is [value missing]. The leakage current detection value flowing through the capacitor structure is then... ;in, This represents the volume resistivity of the insulating medium in the first capacitor; This represents the volume resistivity of the insulating medium in the second capacitor. For example, the highest voltage that a medical device may generate internally during operation is U, which is the maximum DC value that the human body can tolerate, as specified in relevant safety standards. The general safety standards for medical electrical equipment stipulate It is 10 microamps. Generally, this can be adjusted during the design verification phase. , , , , ,make During the mass production assembly stage, the operating voltage U is applied between the casing and the second conductive layer, and the current flowing between them is measured using a multimeter or other means. By adjusting , This causes leakage current. .

[0035] In summary, this solution employs a layered control logic based on different scenarios and indicators to ensure that the total capacitance or current meets the standards. During the design verification phase, multi-parameter collaborative optimization, such as adjusting core parameters like the insulating medium, electrode spacing, conductive layer coupling surface area, and internal height of the casing, controls leakage current and capacitance within safe limits from the design stage, guaranteeing the product's electrical safety performance. During mass production assembly, due to uncontrollable factors such as batch variations in dielectric materials and the stability of dielectric constants, the electrode spacing of the first capacitor can be fine-tuned by adjusting the position of the circuit board inside the casing. Spacing between the second capacitor plates Two core structural dimensions control the total capacitance of the capacitor structure to meet the design requirements of both the lower limit of capacitance and the upper limit of current, thereby ensuring consistency in batch products. During the R&D phase, emphasis is placed on precise parameter optimization and solution flexibility; during mass production, the focus is on process simplification and batch consistency. This approach ensures both the core performance of the antenna's RF operation and meets electrical safety requirements under high-voltage conditions. Simultaneously, it effectively relaxes the product design error range, reduces the requirements for raw materials and processing precision, and significantly improves the product's design tolerance, mass production yield, overall reliability, and versatility.

[0036] The feeding and impedance matching connection relationship between the antenna and the RF circuit is as follows: Antenna 5 is disposed on the outside of the housing 1 to avoid electromagnetic shielding of the antenna 5 radiation by the enclosed housing 1. In the specific physical assembly and electrical circuit connection, the antenna 5 achieves a safe transition of electrical signals from the outside to the inside of the housing 1 through the insulated feedthrough 4. In terms of circuitry, the RF circuit 7 is disposed on the circuit carrier 2 (circuit board 2). The signal output terminal 71 (feed terminal) of the RF circuit 7 is directly electrically connected to the antenna 5 inside the housing 1 to transmit high-frequency RF signals to the outside of the housing 1 without loss and with high efficiency. At the same time, the RF reference ground 72 of the RF circuit 7 is directly electrically connected to the second conductive layer 3, making the second conductive layer 3 the zero-potential electrical reference surface of the RF circuit 7.

[0037] When the system is operating at the antenna frequency, the capacitor structure 9 sandwiched between the second conductive layer 3 and the first conductive layer 11 enables high-frequency AC coupling. This allows the high-frequency RF return signal generated by the RF reference ground 72 of the RF circuit 7 to smoothly return to the first conductive layer 11 of the housing via the second conductive layer 3 and the capacitor structure 9. This design constructs a complete high-frequency closed loop with the path of "signal output terminal 71 - insulating feedthrough 4 - external antenna 5 - first conductive layer 11 of housing 1 - capacitor structure 9 path - second conductive layer 3 - RF reference ground 72", ensuring efficient antenna radiation.

[0038] Because the radiator of the antenna 5 is located outside the housing 1 and close to the high-loss, high-dielectric-constant physiological environment of the human body, its input impedance is prone to deviate from the rated output impedance of the radio frequency circuit (e.g., 50 ohms standard impedance) after implantation, resulting in severe reflection loss of the high-frequency radio frequency signal at the feed end. To solve this technical problem, an impedance matching network 8 is connected across the transmission path between the signal output terminal 71 of the radio frequency circuit 7 and the conductive pin of the insulated feed 4. Physically, the impedance matching network 8 consists of multiple miniature surface-mount components (such as packaged high-Q surface-mount capacitors and surface-mount inductors) arranged on the surface of the circuit carrier, using an L-type, π-type, or T-type topology. Some capacitors or inductors are connected in series on the main signal line between the signal output terminal 71 of the radio frequency circuit 7 and the conductive pin, and some are connected in parallel across the main signal line and the second conductive layer.

[0039] Furthermore, the impedance matching network 8 can also serve as an impedance transformation channel: Firstly, by precisely configuring and fine-tuning the parameter values ​​of the internal series or parallel capacitors and inductors, the impedance matching network 8 achieves conjugate matching between the rated output impedance of the RF circuit and the input impedance of the external antenna radiator. This allows the antenna input impedance to be matched to around 50 ohms, enabling high-frequency RF energy to be delivered to the external antenna radiator with minimal return loss and maximum efficiency through the insulating feedthrough. Secondly, since the second conductive layer 3 achieves low-impedance AC coupling with the first conductive layer 11 (shell 1) at high frequencies through the capacitor structure 9, the impedance matching network, while performing impedance matching on the main signal path, also performs system-level coordinated matching and filtering of the distributed capacitance and capacitive reactance on the RF return path composed of "second conductive layer 3 - insulating medium 6 - first conductive layer 11".

[0040] Combination Figure 2 The equivalent circuit diagram shown illustrates how the distributed capacitance structure and the impedance matching network exhibit distinctly different adaptive physical working processes for AC / DC frequency division under different operating conditions.

[0041] When the implant is in DC operating condition (frequency) When the frequency is 0Hz or extremely low, the equivalent impedance of the capacitor structure 9 tends to infinity, i.e. In the formula, C represents the capacitance value of the capacitor structure 9. Under this DC operating condition, due to the physical barrier of the insulating medium, the path between the second conductive layer 3 (i.e., internal system ground) and the first conductive layer 11 (outer shell ground) presents a DC open circuit state in the equivalent circuit. The DC operating condition specifically includes: the circuit in a normal operating state with DC power supply or static bias, and a single fault state in which the failure of a single electronic component causes the internal DC high voltage source to be abnormally shorted to the reference ground (system GND). Under such DC operating conditions, even if there is a high-voltage DC bias inside, the DC current can never pass through the capacitor structure 9, which presents infinite impedance, to the first conductive layer 11, thereby physically blocking the path of dangerous DC current to the outer shell and the external physiological environment, ensuring the patient's life safety.

[0042] When the implant is at the antenna operating frequency (For example, in the MICS band of 402MHz-405MHz, or the ISM band of 2400MHz-2483.5MHz (center 2.45GHz)) the equivalent high-frequency impedance of the capacitor structure 9 drops sharply and approaches zero (typically) ),Right now At this time, due to the high-frequency polarization linkage of the electric field and the edge electric field in the equivalent circuit, the capacitor path exhibits a radio frequency short circuit (AC conduction) state. In this high-frequency state, the high-frequency radio frequency signal generated by the radio frequency circuit 7 is sent out from the signal output terminal 71 (feed terminal) and flows through the impedance matching network 8 connected in parallel or series between the main signal line and the second conductive layer 3. The impedance matching network 8 achieves conjugate matching (e.g., matching to 50°) between the output impedance of the radio frequency circuit 7 and the input impedance of the antenna radiator through parameter fine-tuning and impedance transformation of inductor and capacitor components. (nearby), so that high-frequency energy can be delivered to the external antenna 5 radiator through the conductive pin of the insulating feed 4 with the lowest return loss and the highest efficiency.

[0043] Meanwhile, at the return end, the high-frequency RF return current generated by the RF reference ground 72 of the RF circuit 7 is directly injected into the second conductive layer 3. Since the second conductive layer 3 achieves low-impedance AC coupling with the first conductive layer 11 of the housing 1 through the distributed capacitance structure 9 at high frequencies, the high-frequency return current can be smoothly and losslessly injected into the first conductive layer 11 through the electromagnetic polarization displacement current path. Due to the extremely low impedance of this high-frequency return path, the housing is effectively pulled down to the RF ground potential at the antenna operating frequency, making the large external area of ​​the first conductive layer 11 an efficient RF return ground network for the antenna, significantly improving the antenna's radiation performance within the body. At this time, while performing impedance matching on the main path, the impedance matching network also performs system-level coordinated matching and filtering of the distributed capacitance and capacitive reactance on the RF return path composed of "second conductive layer 3 - insulating medium 6 - first conductive layer 11," avoiding impedance detuning introduced by stray reactance of the distributed capacitance, and ensuring the long-term stability and efficiency of high-bandwidth neural signal transmission.

[0044] To adapt to different external environments of the implanted device, the antenna radiator is provided in the following form outside the housing: the antenna 5 radiator is exposed and attached to the outside of the closed housing 1, the external pin of the insulating feed 4 is directly connected to the antenna 5 radiator on the outside, and an insulating protective layer is covered on its outer surface.

[0045] To address the extreme electrical and mechanical challenges in clinical medicine, implants have introduced more stringent performance safeguards in terms of spatial layout and physical parameters.

[0046] One feature is the edge clearance design to prevent surface flashover: when the circuit carrier is a circuit board, the outer contour edge of the circuit board extends beyond the outer contour edge of the second conductive layer, forming a preset inward clearance distance. When a patient experiences high-voltage conditions such as cardiac defibrillation, this inward clearance distance artificially lengthens the edge discharge distance (creep distance and electrical clearance) between the two conductive layers, preventing surface flashover or arc breakdown caused by high voltage at the electrode edge. Preferably, a composite insulating layer containing at least two different insulating materials (including a solder resist layer and medical insulating potting material) is provided between the two conductive layers, providing single-fault safety redundancy to the capacitor structure to prevent dielectric solid breakdown.

[0047] Secondly, the mechanical deformation-resistant insulation configuration: the initial equivalent insulation distance between the second conductive layer and the first conductive layer is denoted as d0, and the initial capacitance value is denoted as C0. Under the system operating voltage or single fault voltage U, the withstand breakdown voltage of the insulating medium is denoted as V. When the outer shell is subjected to the maximum preset mechanical stress under physiological conditions (such as bone or muscle compression), the maximum inward indentation deformation is denoted as Δd. max The reduced spacing causes the capacitance of the capacitor structure to increase to C. maxBy increasing the mechanical stiffness of the shell, the constraint deformation satisfies two limit conditions: Condition 1, under DC operating conditions, satisfies: To ensure that even under the most severe pressure, the remaining insulation spacing remains greater than the dielectric breakdown threshold, preventing contact short circuits and maintaining a DC open circuit state to block dangerous DC current; Condition two, at the antenna operating frequency The following conditions must be met: Safety limits are set. Since changes in spacing can cause deviations in capacitance reactance and antenna input impedance, the safety limit for capacitance fluctuation, e, is controlled to be no greater than 5% by increasing the rigidity of the housing. Under this safety limit, the impedance fluctuation of the RF circuit caused by external force deformation is minimal. This ensures that the impedance matching network can still achieve impedance transformation under pressure, thereby maintaining the long-term communication stability of the internal and external wireless links.

[0048] At the operating frequency of antenna 5, the first conductive layer 11, the insulating medium 6, and the coupling conductor 3 also constitute a conformal heat sink structure. This heat sink structure, together with the protective layer on the outer surface, forms a heat dissipation channel, which evenly conducts the localized concentrated heat generated during the operation of the internal circuit to the external physiological environment, effectively reducing the maximum temperature rise of the outer surface of the protective layer.

[0049] In specific clinical applications, the implant can be surgically inserted into specific locations within the patient's body according to different treatment and diagnostic needs: First, it can be embedded within the patient's skull bone window, or attached to the lateral or medial side of the dura mater. In this brain-computer interface scenario, dangerous direct current must absolutely not leak into the highly sensitive cerebrospinal fluid and brain tissue. Second, it can be placed between the subcutaneous tissue of the patient's head and the periosteum on the lateral side of the skull. In this minimally invasive subcutaneous brain-computer interface scenario, the second conductive layer conforms to the physiological curvature of the skull, forming a conformal stacked arrangement with the first conductive layer of the shell in the coupling area, achieving efficient radiofrequency recirculation under an extremely thin scalp. Third, it can be placed in the subcutaneous tissue of the anterior wall of the patient's chest cavity or in an implantation pocket below the pectoralis major muscle. In this cardiac pacemaker scenario, the insulating medium can resist the penetration of moist tissue fluid from the pleural cavity, and the capacitor structure has insulating redundancy to withstand external cardiac defibrillation impacts. Fourth, it can be placed within the subcutaneous fat layer of the patient's waist, abdomen, buttocks, or limbs. In this neurostimulator scenario, when the implant is subjected to mechanical stress from muscle movement or bone compression, the shell stiffness configuration can control the concave deformation within the constraints, preventing antenna impedance detuning.

[0050] At the system application level, this invention provides a brain-computer interface system, including the aforementioned implant and an external unit. The implant is configured to be placed inside a patient's body to process neural signals. The external unit is located outside the patient's body and is equipped with an external radio frequency transceiver circuit and an external antenna.

[0051] The antenna's operating frequency is the radio frequency used for data exchange between the implant and the external unit. The system's DC operating conditions include the DC power supply status of the electrical system when processing neural signals or receiving wireless power from the external unit, as well as fault conditions involving DC leakage.

[0052] At the process flow level, the present invention provides a method for preparing an implant, comprising: determining a first spacing and a second spacing based on the constraint relationship between the lower limit of the total equivalent capacitance of the capacitor structure, the upper limit of the leakage current, and the spacing; determining the target position of the circuit board inside the housing based on the first spacing and the second spacing; adjusting the positioning structure disposed inside the housing to position and fix the circuit board to the target position; wherein the first spacing represents the distance between the upper surface of the second conductive layer and the first conductive layer at the top of the housing; and the second spacing represents the distance between the lower surface of the second conductive layer and the first conductive layer at the bottom of the housing.

[0053] Optionally, the positioning structure may be, for example, but not limited to, silicone. Specifically, a tooling fixture is used to temporarily fix the circuit board to the target position inside the housing to maintain the first gap and the second gap between the second conductive layer and the first conductive layer; a fluid insulating medium (such as medical silicone) is injected into the area where the first gap and the second gap are located and cured to form a cured insulating layer that fills the first gap and the second gap and adheres to the circuit board and the inner wall of the housing; the cured insulating layer constitutes the insulating medium in the capacitor structure and serves as the positioning structure to fix the circuit board to the target position.

[0054] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0055] Based on the above-described preferred embodiments of the present invention, and through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention. That is, the technical scope of the present invention is not limited to the contents of the specification.

Claims

1. An implant, characterized in that, include: A housing, which is enclosed inside and has a circuit, wherein the inner surface of the housing is provided with a first conductive layer; The antenna is disposed on the outside of the housing and electrically connected to the circuit inside the housing via an insulated feedthrough. A coupling conductor, housed inside the housing and connected to the reference ground of the circuit, is disposed opposite to the first conductive layer and an insulating medium is sandwiched between them, so that the coupling conductor, the insulating medium and the first conductive layer constitute a capacitor structure; Under DC operating conditions, the capacitor structure is in a DC open circuit state to block the DC current conducted to the first conductive layer; At the antenna operating frequency, the capacitor structure achieves AC coupling, making the first conductive layer the radio frequency return ground of the antenna.

2. The implant according to claim 1, characterized in that, The interior of the housing contains a circuit carrier; The coupling conductor is a second conductive layer disposed on the circuit carrier; The second conductive layer, the insulating medium, and the first conductive layer are arranged in a conformal stack or in parallel adjacent arrangement.

3. The implant according to claim 2, characterized in that, The upper surface of the second conductive layer is disposed opposite to the first conductive layer on the top of the shell and is isolated by an insulating medium to form a first capacitor; The lower surface of the second conductive layer is disposed opposite to the first conductive layer at the bottom of the housing and is isolated by an insulating medium to form a second capacitor; as well as The first capacitor and the second capacitor are connected in parallel to form the capacitor structure.

4. The implant according to claim 3, characterized in that, The implant also includes a positioning structure for defining the position of the circuit carrier inside the housing; The positioning structure is configured to: adjust the spacing between the upper and lower surfaces of the second conductive layer and the first conductive layer, so that the total equivalent capacitance of the capacitor structure at the antenna operating frequency is not less than the lower limit of capacitance, and / or so that the leakage current of the capacitor structure under DC conditions is not greater than the upper limit of current.

5. The implant according to claim 4, characterized in that, At the antenna operating frequency, the constraint relationship between the lower limit of the capacitance and the spacing is C. ;in This represents the absolute dielectric constant of the insulating medium in the first capacitor. This represents the absolute dielectric constant of the insulating medium in the second capacitor. This indicates the first [plate / electrode] between the opposite plates in the first capacitor. , This indicates the second capacitor with respect to the relative plates. S represents the overlapping projected area of ​​the second conductive layer and the first conductive layer, and C represents the capacitance value of the capacitor structure. This indicates the capacitance value of the first capacitor. This indicates the capacitance value of the second capacitor. This indicates the lower limit of capacitance for the capacitor structure.

6. The implant according to claim 4, characterized in that, Under DC operating conditions, the constraint relationship between the upper limit of the leakage current and the spacing is as follows: ;in, This represents the volume resistivity of the insulating medium in the first capacitor; This represents the volume resistivity of the insulating dielectric in the second capacitor. First second S represents the overlapping projected area of ​​the second conductive layer and the first conductive layer, and U represents the maximum operating voltage of the system. This indicates the upper limit of leakage current of the capacitor structure. This represents the leakage current detection value of the capacitor structure.

7. The implant according to claim 2, characterized in that, The circuit carrier is a circuit board, and the second conductive layer is a grounded copper layer disposed on the surface or inner layer of the circuit board.

8. The implant according to claim 1, characterized in that, The circuit includes a radio frequency circuit; The signal output terminal of the radio frequency circuit is electrically connected to the antenna inside the housing, and the radio frequency reference ground of the radio frequency circuit is electrically connected to the coupling conductor inside the housing.

9. A brain-computer interface system, characterized in that, include: The implant according to any one of claims 1-8, wherein the implant is configured to be implanted in a patient to process neural signals; The external unit is placed outside the patient's body and is equipped with an external radio frequency transceiver circuit and an external antenna. The operating frequency of the antenna is the radio frequency used for data exchange between the implant and the external device; the DC operating condition includes the DC power supply state of the implant when processing nerve signals or receiving wireless power from the external device, or the fault state in which DC leakage occurs.

10. A method for preparing an implant as described in any one of claims 1-8, characterized in that, include: Based on the constraint relationship between the lower limit of the total equivalent capacitance of the capacitor structure, the upper limit of the leakage current, and the spacing, the first spacing and the second spacing are determined. The target position of the circuit carrier inside the housing is determined based on the first spacing and the second spacing. Adjust the positioning structure located inside the housing to position and fix the circuit carrier to the target position; in The first spacing represents the distance between the upper surface of the second conductive layer and the first conductive layer at the top of the shell; The second spacing represents the distance between the lower surface of the second conductive layer and the first conductive layer at the bottom of the housing.

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