An intervention type brain-computer interface system based on a micro-needle balloon, an implantation method, an application and a preparation method

Abstract

The application belongs to the technical field of brain-computer interface, and particularly relates to an intervention type brain-computer interface system based on a micro-needle balloon, which comprises a balloon micro-needle electrode, a wire bundle, a controller and a control terminal outside the body in the body; wherein the micro-needle electrode is fixed to the surface of the balloon, is sent to a cerebral target blood vessel through the intervention of a human body blood vessel; after the balloon expands to make the micro-needle pierce into the intima layer of the blood vessel wall, the balloon is separated from the micro-needle, the balloon is withdrawn from the body, and the neural electric signal is collected or electric stimulation is implemented through the micro-needle electrode which is anchored in the cerebral blood vessel wall at a close distance. The wire bundle is led out from the cervical blood vessel, is completely implanted subcutaneously, is connected with the controller in the body, and realizes the wireless transmission and wireless power supply of the signal through the controller. The application does not need to open the skull, has small trauma, stable signal, good biocompatibility, can be used for the reconstruction of motor function, neural regulation and rehabilitation treatment, solves the problems of large trauma of traditional invasive type and poor signal of non-invasive type, and has a wide clinical application prospect.

Description

Technical Field

[0001] This invention belongs to the field of brain-computer interface technology, specifically relating to an interventional brain-computer interface system based on a microneedle balloon, its implantation method, application, and preparation method. Background Technology

[0002] Brain-computer interface (BCI) is a technology that establishes communication and control pathways between the brain and external devices. Its core principle is to directly control external devices by capturing bioelectrical signals generated by the brain, or to regulate brain activity through external stimuli, thereby enhancing, improving, and extending brain function. BCI implementation methods are mainly divided into three categories: invasive, non-invasive, and interventional. Among these, invasive BCI remains the mainstream research direction and has already achieved practical applications in multiple fields.

[0003] In the field of motor function assistance, invasive brain-computer interfaces can effectively control external assistive devices by accurately collecting brain neural signals related to limb movement and analyzing the user's movement intentions. For example, they can help paraplegic patients control smart prostheses to complete actions such as walking and picking up objects through EEG signals, assist spinal cord injury patients to control robotic arms to complete daily activities such as drinking and eating, and enable text input by driving virtual keyboards through EEG signals.

[0004] Despite the significant effects of invasive brain-computer interfaces, there are still obvious limitations: the technology usually requires craniotomy to implant electrodes into the cerebral cortex or deep brain regions, which not only increases the surgical risk for patients but also easily triggers the body's immune rejection reaction; at the same time, the electrodes need to be in direct contact with brain tissue, which places extremely high demands on the biocompatibility and signal acquisition accuracy of the electrodes, resulting in high technical difficulty in electrode research and development and prominent technical barriers in the industry.

[0005] Non-invasive brain-computer interfaces do not require invasive surgery. They only require an EEG signal acquisition device to be worn on the scalp to complete signal capture. They are non-invasive and cause less harm to the human body, and the technical development difficulty is relatively low. However, the core drawback of non-invasive brain-computer interfaces is that the acquisition device is far from the cerebral cortex and is subject to interference from tissues such as the scalp and skull. This makes it difficult to achieve continuous, stable and accurate capture of EEG signals, which limits its application in high-precision scenarios.

[0006] While existing interventional brain-computer interfaces can achieve minimally invasive implantation, they generally suffer from problems such as poor adhesion between electrodes and blood vessel walls and insufficient stability.

[0007] Therefore, this invention provides a minimally invasive, non-craniotomy, stable, and high-signal-quality intravascular brain-computer interface to overcome the shortcomings of existing technologies. Summary of the Invention

[0008] To address the aforementioned shortcomings of existing technologies, this invention provides an interventional brain-computer interface system based on a microneedle balloon, its implantation method, application, and preparation method, which solves the problems of large trauma in traditional invasive methods and poor signal in non-invasive methods.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] One of the objectives of this invention is to provide an interventional brain-computer interface system based on a microneedle balloon, which addresses the problems of large trauma in traditional invasive methods and poor signal in non-invasive methods.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows:

[0012] An interventional brain-computer interface system based on a microneedle balloon includes an in vivo part and an external part. The in vivo part includes a balloon microneedle electrode, a lead bundle, and an in vivo controller. The external part includes an external controller, a wireless charging device, and a mobile terminal. The balloon microneedle electrode includes a balloon, a microneedle electrode array fixed to the surface of the balloon, and lead wires. The microneedle electrode array and the balloon are detachably connected through a water-sensitive connection layer. After the microneedle electrode array is placed in the vascular intima, the balloon is withdrawn from the body. The microneedle electrode array is converged into a lead bundle by the lead wires. The lead bundle is led out from the patient's neck and connected to the in vivo controller implanted in the patient's body. The in vivo controller is electrically connected to the microneedle electrode array through the lead bundle for acquiring electroencephalogram (EEG) signals or applying electrical stimulation, and communicates wirelessly with the external controller. The external controller is used to receive the EEG signals or send control commands to assist the patient's motor function or regulate neurological diseases.

[0013] Further optimized design: the microneedle electrode array includes multiple independently arranged microneedle units, each microneedle unit including a microneedle tip, a microneedle substrate, and a conductive layer; the microneedle tip is made of a photocurable resin material, the microneedle substrate is made of a water-absorbing and swelling material, and the conductive layer covers the surface of the microneedle tip or the microneedle substrate; the water-sensitive connection layer is disposed at the contact interface between the microneedle substrate and the balloon, and the water-sensitive connection layer undergoes structural changes when subjected to specific stimuli, causing the microneedle electrode array to separate from the balloon.

[0014] Further design optimization: the microneedle tip is teardrop-shaped with a tip angle of 25° to 30°, and the microneedle root has an outwardly protruding arc structure; the height of the microneedle tip is 50μm to 250μm, and the center distance between adjacent microneedle units is 100μm; both the microneedle base and the outer layer of the lead bundle are coated with anticoagulant molecules, and the anticoagulant molecules are heparin.

[0015] Further design optimization involves using a photocurable resin material that is either polyethylene glycol diacrylate (PEGDA) or a composite material of a conductive polymer, wherein the conductive polymer is PEDOT:PSS; the water-absorbing and swelling material is polyvinyl alcohol (PVA); and the water-sensitive connecting layer is formed by curing a mixture of PVA aqueous solution and boric acid. The connection between the microneedle electrode array and the balloon is achieved through dynamic covalent bonds formed between the PVA hydroxyl groups and boric acid. When physiological saline is injected into the surface of the balloon, the PVA absorbs water and swells, breaking the dynamic covalent bonds and causing the microneedle electrode array to separate from the balloon.

[0016] With further design optimization, the in vivo controller integrates a wireless charging module and an information transmission module; the wireless charging module is used to power the in vivo controller and the microneedle electrode array and output electrical stimulation pulses; the information transmission module is used to amplify, filter, and perform analog-to-digital conversion on the acquired EEG signals, and wirelessly transmit the digital data to the external controller; the external controller establishes a wireless connection with the in vivo controller via Bluetooth.

[0017] The second objective of this invention is to provide a method for preparing a balloon microneedle electrode.

[0018] To achieve the above objectives, the technical solution of the present invention is as follows:

[0019] A method for preparing a balloon microneedle electrode includes the following steps: S1. Prepare a photocurable resin solution, inject it into the micropores of the microneedle array mold, remove air bubbles by centrifugation, and cure it under ultraviolet light to obtain the microneedle tip; S2. Prepare a water-absorbing and swelling material solution, cover it above the microneedle tip, dry it, and then peel off the mold to obtain a microneedle substrate patch with microneedle tip; S3. Metal sputtering or spraying is performed on the microneedle substrate patch to form a conductive layer on the surface of the microneedle; S4. Coat the microneedle substrate patch and the balloon bonding surface with a bonding agent, and dry at low temperature to connect the two through reversible chemical bonds, thus completing the assembly of the balloon microneedle electrode.

[0020] Further design optimization: In step S1, the photocurable resin solution is prepared from polyethylene glycol diacrylate (PEGDA), photoinitiator 2959, and deionized water; the wavelength of the ultraviolet light irradiation is 365 nm, the light intensity is 9 mW / cm², and the curing time is 10 minutes; In step S3, the metal is platinum or gold, the thickness of the conductive layer formed by sputtering or spraying is 1000 nm, and the surface coverage is greater than or equal to 98%.

[0021] The third objective of this invention is to provide an implantation method for an interventional brain-computer interface system based on a microneedle balloon, for implanting the brain-computer interface system into the brain.

[0022] To achieve the above objectives, the technical solution of the present invention is as follows:

[0023] An implantation method for an interventional brain-computer interface system based on a microneedle balloon, characterized by comprising the following steps: A1. Establish a vascular access through femoral vein or jugular vein puncture, and deliver the microcatheter loaded with the balloon microneedle electrode along the guidewire to the target vascular region of the brain. A2. Push the balloon microneedle electrode out of the microcatheter, inject gas into the balloon to make the balloon expand radially, press the microneedle electrode array against the inner wall of the blood vessel and penetrate the intima layer of the blood vessel; A3. Mild saline solution is injected into the surface of the balloon through a microcatheter to cause the water-absorbing and swelling material of the microneedle base to swell, thereby disrupting the reversible connection between the microneedle electrode array and the balloon. The balloon is then withdrawn, leaving the microneedle electrode array in the vascular intima. A4. The lead bundle is withdrawn along the vascular path to the subcutaneous tissue of the neck, brought out through the surgical incision and connected to the internal controller to complete the implantation.

[0024] Further design optimization: in step A2, the balloon inflation pressure is controlled between 0.6 atm and 1.2 atm; in step A3, after injecting saline, wait 3 to 5 minutes for the microneedle base to fully swell and separate from the balloon; the target vascular region is the cerebral venous sinus, preferably the middle segment of the superior sagittal sinus.

[0025] The fourth objective of this invention is to provide a method for applying an interventional brain-computer interface system based on a microneedle balloon in rehabilitation medicine.

[0026] To achieve the above objectives, the technical solution of the present invention is as follows:

[0027] A method for applying an interventional brain-computer interface system based on microneedle balloons in rehabilitation medicine is described, which is used to: collect electroencephalogram (EEG) signals corresponding to the motor cortex of the patient's brain, analyze the patient's motor intentions, and drive external assistive devices or virtual reality devices to reconstruct motor functions; or, apply electrical stimulation with specific parameters to the patient's central nervous system to regulate neural activity, for rehabilitation training of patients with spinal cord injuries or electrotherapy for neurological diseases.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention employs a minimally invasive intravascular interventional implantation method. By expanding a balloon, the microneedle electrode is tightly attached to and inserted into the inner wall of the blood vessel, achieving stable fixation of the electrode within the blood vessel. This prevents displacement and detachment, ensuring long-term reliability. Simultaneously, the microneedle electrode maintains extremely close proximity to the brain tissue outside the blood vessel, significantly reducing signal transmission attenuation and external interference. This enables stable, accurate, and high signal-to-noise ratio acquisition of EEG signals, combining excellent signal acquisition quality with reliable implantation fixation. Furthermore, it eliminates the need for craniotomy, resulting in minimal trauma and high biocompatibility. It can simultaneously achieve neural signal acquisition and electrical stimulation functions. Overall, its safety, stability, and practicality are significantly superior to existing invasive and non-invasive brain-computer interfaces. Attached Figure Description

[0030] Figure 1 This invention provides a schematic diagram of the usage status of an interventional brain-computer interface system based on a microneedle balloon, as an embodiment of the present invention.

[0031] Figure 2 This invention provides a schematic diagram of the microneedle structure in an interventional brain-computer interface system based on a microneedle balloon, as an embodiment of the present invention.

[0032] Figure 3 This invention provides a diagram (20-channel version) showing the arrangement of microneedle electrodes in an interventional brain-computer interface system based on a microneedle balloon.

[0033] Figure 4 A flowchart illustrating a method for preparing a balloon microneedle electrode is provided in this embodiment of the invention.

[0034] Figure 5 This is a schematic diagram illustrating the state of microneedle electrodes implanted in the vascular intima in an interventional brain-computer interface system based on a microneedle balloon, as provided in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] To better explain the technical solution, the following technical terms are explained:

[0037] This application provides an interventional brain-computer interface system based on balloon microneedle electrodes, comprising an in vivo part and an external part.

[0038] The in vivo components include: balloon microneedle electrodes, lead bundle, and in vivo controller.

[0039] The external components include: an external controller, a wireless charging device, and a mobile terminal.

[0040] The balloon microneedle electrode consists of a balloon, a microneedle electrode, and a wire. The microneedle electrode is fixed to the surface of the balloon and is insulated from the balloon.

[0041] The microneedle electrode material is made of UV-curable resin PEGDA, PEDOT:PSS, photoinitiator 2599, LAP, conductive silver paint, or platinum, gold, and other metallic materials. Platinum not only has good conductivity but also good biocompatibility and low toxicity to humans.

[0042] For the mid-segment of the superior sagittal sinus in adults (the segment corresponding to the M1 motor cortex in the precentral gyrus, with a total sinus wall thickness of 700–1200 μm, composed of 10–30 μm endothelium, 150–250 μm subendothelial connective tissue, and 550–950 μm dense outer dura mater), the microneedles are designed with a height of 50 μm–250 μm and a tip angle of 25–30°. This configuration avoids the risk of intracranial hemorrhage and cerebrospinal fluid leakage caused by dural puncture, and can also effectively detect delta to low gamma frequency EEG potentials, motor and somatosensory evoked potentials in the primary motor cortex.

[0043] The microneedles are teardrop-shaped, with a total tip height of 120 μm and a convex arc (R25 μm) at the base. The needle body is narrower at the top and wider at the bottom, with a rounded, bulging base, forming an overall teardrop configuration. The center-to-center distance between adjacent microneedles is 100 μm. The tapered tip of the needle gradually narrows upwards: during puncture, the tip concentrates stress, resulting in high pressure that easily punctures the vascular endothelial cell layer. The vascular intima is a viscoelastic soft tissue; upon puncture, the tissue undergoes elastic deformation due to compression. After insertion, the arc-shaped segment of the microneedle completely sinks into the intimal matrix, and the intimal soft tissue retracts elastically, with the bulging arc-shaped structure being enveloped by the intimal soft tissue. Within hours after microneedle implantation, intimal cells and the extracellular matrix slowly grow and creep along the arc-shaped contour, enveloping the base of the arc. After cell proliferation, the microneedles are further integrated at the biological tissue level, achieving long-term fixation within the vascular intima.

[0044] When the microneedle patch is affected by intravascular flow, the arc surface of the microneedle can be effectively converted into radial compressive stress and shear stress of the intima. The intima will generate a reverse clamping friction force on the arc. The single needle is anchored locally by the arc. After the array is arranged, the intima between the needles is pulled and tightened. The center distance between adjacent microneedles is 100 μm. Adjacent microneedles restrain each other, and the pull-out resistance of a single microneedle is also distributed by the surrounding tissue.

[0045] After the microneedle patch is implanted, only the microneedle base is exposed in the blood vessel. The base of the microneedle is made of PVA material and coated with a layer of heparin molecules, which has an anticoagulant effect.

[0046] Microneedle electrodes can be used to collect brain signals and also as stimulation electrodes to apply electrical stimulation to adjacent brain regions. Leads are led out from the bottom of the microneedle, converge into a lead bundle under the microneedle patch, run along the blood vessels, exit from the jugular vein, and connect to an in vivo controller implanted under the skin of the chest.

[0047] The in-vivo controller integrates a wireless charging module and an information transmission module. The wireless charging module powers the in-vivo system and outputs electrical stimulation pulses; the information transmission module amplifies, filters, and converts signals from analog to digital, and wirelessly transmits the data to the external system.

[0048] The external system includes terminals such as mobile phones and computers, which receive neural signals via Bluetooth. The terminals decode the signals in real time, analyze the motor intention or neural state, generate control commands or treatment strategies, and send stimulation parameters to the internal controller. The internal controller is powered by a wireless charging module, driving the microneedle electrodes to output constant current electrical stimulation, realizing closed-loop regulation of acquisition-decoding-stimulation, which can be used for motor reconstruction, rehabilitation training, or treatment of neurological diseases.

[0049] This embodiment provides an implantation method for an interventional brain-computer interface system based on a microneedle balloon:

[0050] 1. Preoperative preparation

[0051] The interventional catheter, guidewire, and balloon microneedle electrode are sterilized with ethylene oxide. Intravenous access is established, and the patient's groin area (femoral vein) or jugular vein area is disinfected and draped.

[0052] 2. Puncture and delivery

[0053] The femoral vein was punctured using the Seldinger technique, and a catheter sheath was inserted. The microcatheter loaded with a balloon microneedle electrode was then advanced along the guidewire through the femoral vein, inferior vena cava, right atrium, and internal jugular vein to reach the target venous segment in the brain. Digital subtraction angiography (DSA) was used throughout the procedure to ensure that the electrode was positioned within the corresponding blood vessel in the target brain region.

[0054] 3. Balloon dilation and fixation

[0055] After the microcatheter is in place, fix the catheter, push the microneedle balloon out of the catheter, slowly inject air into the balloon to make it expand radially, press the microneedle electrode against the inner wall of the blood vessel, and control the balloon expansion pressure at 0.6–1.2 atm to avoid damaging the blood vessel.

[0056] After the microneedle fully penetrates the vascular intima, the tissue rebound and encircling effect causes the microneedle to adhere tightly to the intima. Subsequently, 45 °C saline is injected into the balloon surface through a microcatheter to accelerate the swelling of the material. After about 3 minutes, the PVA base of the microneedle absorbs water and swells, breaking the reversible chemical bonds at the interface and causing the microneedle to separate from the balloon. At this point, the balloon is slowly withdrawn, leaving the microneedle in place in the blood vessel. Because the microneedle base and the outer insulating layer of the lead wire are covered with heparin molecules, which have an anticoagulant effect, the impact on the blood is minimal.

[0057] 4. Wire lead-out and controller installation

[0058] The lead wire bundle is withdrawn along the vascular pathway to the subcutaneous tissue of the neck. A small incision is made in the neck to bring out the lead wire bundle and connect it to a subcutaneously implanted internal controller. The controller is then placed subcutaneously in the chest, and the incision is sutured layer by layer to complete the minimally invasive implantation.

[0059] This embodiment provides a method for preparing a balloon microneedle electrode:

[0060] (1) Preparation of microneedle tip solution

[0061] PEGDA(400) was selected as the photocurable matrix material, and a PEGDA(400) deionized water solution with a concentration of 0.2 g / mL-0.6 g / mL was prepared. The solvent used was ultrapure deionized water at a constant temperature of 60 ℃ to accelerate the complete dissolution of monomers and avoid solute agglomeration that would affect the accuracy of needle tip forming.

[0062] Add photoinitiator 2959 to the system until the initiator concentration is 1 mg / mL, stir magnetically at 60 °C for 30 min at a stirring speed of 300 r / min-800 r / min until the solution is clear and transparent and the initiator is uniformly dispersed.

[0063] (2) Preparation of microneedle base solution

[0064] PVA was selected as the flexible substrate material, and a PVA deionized aqueous solution of 0.2 g / mL-0.6 g / mL was prepared. The solution was then magnetically stirred at 60 °C for 1-2 h until the PVA was completely dissolved.

[0065] (3) The balloon is a common commercial balloon with a diameter range of 2-4 mm (under expansion). The conductive wire is a commercial platinum wire with a diameter of 0.01 mm-0.02 mm, which is bonded to the bottom of the microneedle. The wire also has an insulating layer on the outside.

[0066] (3) Preparation of microneedles

[0067] Measure 300 μL of the needle tip solution and inject it into the micropore area of ​​the microneedle array mold. Use horizontal centrifugation to fill the pores with the solution, controlling the centrifugation speed at 3000–5000 r / min and the centrifugation time at 5–8 min, at a constant temperature of 25 ℃. Horizontal centrifugation completely removes air bubbles from the mold micropores and prevents solution splashing. Excess solution on the mold surface is scraped off to ensure uniform needle tip height and morphology. After completion, the bent wire is attached to the bottom of the microneedle.

[0068] The filled microneedle mold was placed on a UV curing stage for photocuring. The UV wavelength was 365nm, the UV light intensity was 9 mW / cm², and the curing time was 10 min. ① The UV wavelength of 365nm is the optimal response band for photoinitiator 2959, which can maximize the initiation of PEGDA monomer crosslinking polymerization; ② When the light intensity is too low, the degree of monomer crosslinking is insufficient, resulting in poor mechanical strength of the microneedle tip; when the light intensity is too high, it will cause local over-crosslinking, generating internal stress at the tip and causing microcracks; ③ A curing time of 10 min ensures complete curing of the tip. A curing time of less than 8 min results in insufficient curing, making the tip soft and easily deformable; a curing time of more than 15 min does not improve performance but instead accelerates mold aging. After curing, the compressive strength of the microneedle substrate is around 40 MPa, and the designed puncture resistance of the microneedle tip is between 1.0 and 1.2 MPa.

[0069] After curing, 280 μL of PVA substrate solution was precisely measured and evenly applied to the top of the mold needle tips. Excess solution was scraped off the mold surface, and the substrate solution was defoamed at 1500 r / min for 3 min to eliminate air bubbles. The mold was then placed in a constant temperature drying oven at 40 ℃ for 12 h to slowly evaporate moisture and prevent substrate cracking and warping caused by rapid drying. After drying, the substrate was peeled off at a uniform speed along the edge of the mold to obtain a microneedle array patch with a complete structure, uniform needle tips, and no damage.

[0070] (4) Spraying nano-platinum

[0071] The prepared microneedle patch is flattened and fixed onto a clean glass slide with the needle tip facing upwards, ensuring the patch is wrinkle-free and without misalignment. The fixed microneedle patch is then placed in an ion sputtering apparatus with a current of 10-20 mA, a vacuum level below 0.05 Bar, and a sputtering time of 120-180 s (depending on the size of the microneedle patch). The same parameters are used to spray the bottom of the microneedles, achieving uniform coating on both sides. This strengthens the adhesion between the conductive layer and the microneedle substrate. After spraying, the conductive layer thickness is controlled to 1000 nm, with a surface coverage of ≥98%, ensuring no exposed needle tips, no paint buildup blocking pores, and no thick layer accumulation. The conductive layer thickness should not exceed 1500 nm, as this can lead to microneedle tip passivation and increased resistance during puncture. If it is too thin, the electrode impedance will not increase sufficiently, and baseline noise will rise.

[0072] To meet the requirements for acquiring EEG signals from the mid-segment superior sagittal sinus in adults, platinum-based electrodes were used in this case, with a conductivity of ≥2.2×10⁻⁶ in the needle tip sensing area. 6 S / m can stably acquire EEG signals.

[0073] (5) Combination of microneedle electrode with balloon

[0074] Prepare 5 ml of a mixture of 8% PVA aqueous solution and 0.8% medical boric acid (BA), and apply a thin layer to the bonding surface between the balloon and the PVA substrate. Dry at 40 ℃ for 2 h to solidify. The PVA hydroxyl groups and boric acid form a dynamic borate ester reversible covalent bond + high-density hydrogen bond. If the balloon does not delaminate after repeated inflation and deflation, it meets the requirements for intracranial catheter delivery and balloon expansion to push the microneedle into the superior sagittal sinus endothelium.

[0075] This embodiment provides a method for applying an interventional brain-computer interface system based on a microneedle balloon in rehabilitation medicine. It is used to: collect electroencephalogram (EEG) signals corresponding to the patient's motor cortex, analyze the patient's motor intentions, and drive external assistive devices or virtual reality devices to reconstruct motor function; or, apply electrical stimulation with specific parameters to the patient's central nervous system to regulate neural activity, for use in rehabilitation training for patients with spinal cord injuries or electrotherapy for neurological diseases.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications should be covered within the scope of the claims of the present invention.

Claims

1. An interventional brain-computer interface system based on a microneedle balloon, characterized in that, The device comprises an in vivo component and an external component. The in vivo component includes a balloon-shaped microneedle electrode, a lead bundle, and an in vivo controller. The external component includes an external controller, a wireless charging device, and a mobile terminal. The balloon-shaped microneedle electrode includes a balloon, a microneedle electrode array fixed to the surface of the balloon, and lead wires. The microneedle electrode array and the balloon are detachably connected via a water-sensitive connection layer. After the microneedle electrode array is placed in the vascular intima, the balloon is withdrawn from the body. The microneedle electrode array is converged into a lead bundle via the lead wires. The lead bundle extends from the patient's neck and connects to the in vivo controller implanted in the patient's body. The in vivo controller is electrically connected to the microneedle electrode array via the lead bundle to acquire electroencephalogram (EEG) signals or apply electrical stimulation, and communicates wirelessly with the external controller. The external controller receives the EEG signals or sends control commands to assist the patient's motor function or regulate neurological diseases.

2. The interventional brain-computer interface system based on microneedle balloon as described in claim 1, characterized in that: The microneedle electrode array includes multiple independently arranged microneedle units. Each microneedle unit includes a microneedle tip, a microneedle substrate, and a conductive layer. The microneedle tip is made of a photocurable resin material, the microneedle substrate is made of a water-absorbing and swelling material, and the conductive layer covers the surface of the microneedle tip or the microneedle substrate. The water-sensitive connecting layer is disposed at the contact interface between the microneedle substrate and the balloon. When the water-sensitive connecting layer is subjected to a specific stimulus, it undergoes a structural change, causing the microneedle electrode array to separate from the balloon.

3. The interventional brain-computer interface system based on microneedle balloon as described in claim 2, characterized in that: The microneedle tip is teardrop-shaped with a tip angle of 25° to 30° and an outwardly protruding arc structure at the root of the microneedle; the height of the microneedle tip is 50μm to 250μm and the center distance between adjacent microneedle units is 100μm; both the microneedle base and the outer layer of the lead bundle are coated with anticoagulant molecules, which are heparin.

4. The interventional brain-computer interface system based on microneedle balloon as described in claim 2, characterized in that: The photocurable resin material is any one of polyethylene glycol diacrylate and conductive polymer; the water-absorbing and swelling material is PVA; the water-sensitive connecting layer is formed by mixing PVA aqueous solution and boric acid and then curing it; the connection between the microneedle electrode array and the balloon is achieved through the dynamic covalent bond formed by the PVA hydroxyl group and the boric acid; when physiological saline is injected into the surface of the balloon, the PVA absorbs water and swells, breaking the dynamic covalent bond, thereby separating the microneedle electrode array from the balloon.

5. The interventional brain-computer interface system based on microneedle balloon as described in claim 1, characterized in that: The in vivo controller integrates a wireless charging module and an information transmission module; the wireless charging module is used to power the in vivo controller and the microneedle electrode array and output electrical stimulation pulses; the information transmission module is used to amplify, filter and convert the acquired EEG signals into analog and digital data, and wirelessly send the digital data to the external controller; the external controller establishes a wireless connection with the in vivo controller via Bluetooth.

6. A method for preparing a balloon microneedle electrode, characterized in that, Includes the following steps: S1. Prepare a photocurable resin solution, inject it into the micropores of the microneedle array mold, remove air bubbles by centrifugation, and cure it under ultraviolet light to obtain the microneedle tip; S2. Prepare a water-absorbing and swelling material solution, cover it above the microneedle tip, dry it, and then peel off the mold to obtain a microneedle substrate patch with microneedle tip; S3. Metal sputtering is performed on the microneedle substrate patch to form a conductive layer on the surface of the microneedle; S4. Coat the microneedle substrate patch and the balloon bonding surface with a bonding agent, and dry at low temperature to connect the two through reversible chemical bonds, thus completing the assembly of the balloon microneedle electrode.

7. The method for preparing the balloon microneedle electrode as described in claim 6, characterized in that: In step S1, the photocurable resin solution is prepared from polyethylene glycol diacrylate, photoinitiator 2959 and deionized water. The wavelength of the ultraviolet light irradiation is 365 nm, the light intensity is 9 mW / cm², and the curing time is 10 minutes. In step S3, the metal is platinum, the thickness of the conductive layer formed by sputtering is 1000 nm, and the surface coverage is greater than or equal to 98%.

8. An implantation method for an interventional brain-computer interface system based on a microneedle balloon, characterized in that, Includes the following steps: A1. Establish a vascular access through femoral vein or jugular vein puncture, and deliver the microcatheter loaded with the balloon microneedle electrode along the guidewire to the target vascular region of the brain. A2. Push the balloon microneedle electrode out of the microcatheter, inject gas into the balloon to make the balloon expand radially, press the microneedle electrode array against the inner wall of the blood vessel and penetrate the intima layer of the blood vessel; A3. Mild saline solution is injected into the surface of the balloon through a microcatheter to cause the water-absorbing and swelling material of the microneedle base to swell, thereby disrupting the reversible connection between the microneedle electrode array and the balloon. The balloon is then withdrawn, leaving the microneedle electrode array in the vascular intima. A4. The lead bundle is withdrawn along the vascular path to the subcutaneous tissue of the neck, brought out through the surgical incision and connected to the internal controller to complete the implantation.

9. The implantation method of the interventional brain-computer interface system based on microneedle balloon as described in claim 8, characterized in that, In step A2, the balloon inflation pressure is controlled between 0.6 atm and 1.2 atm; in step A3, after injecting saline, wait 3 to 5 minutes for the microneedle base to fully swell and separate from the balloon; the target vascular region is the cerebral venous sinus.

10. A method for applying an interventional brain-computer interface system based on a microneedle balloon in rehabilitation medicine, characterized in that, Used for: Collect EEG signals corresponding to the patient's motor cortex, analyze the patient's motor intentions, and drive external assistive devices or virtual reality devices to reconstruct motor function; Alternatively, electrical stimulation with specific parameters can be applied to the patient's central nervous system to regulate neural activity, and can be used for rehabilitation training of patients with spinal cord injuries or electrotherapy for neurological diseases.

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