Rodent subcutaneous magnetic guide minimally invasive embedded hydrogel electrode system

Abstract

The invention provides a rodent subcutaneous magnetic guide minimally invasive embedded hydrogel electrode system. The implanted magnetic nail is inserted into subcutaneous muscular tissue through a skin wound, and the external magnet interacts with the implanted magnetic nail in vitro so as to guide the flexible electrode substrate-soft hydrogel electrode complex to be implanted into a target position based on the action between the magnets, so that the implanted magnetic nail is separated from the complex and taken out of the body. The soft hydrogel electrode is embedded into the packaging layer of the flexible electrode substrate and is adhered to the surface of an electrode point of the conductive metal layer; one end of the flexible electrode substrate is provided with an opening for inserting and implanting the magnetic nail, and the other end of the flexible electrode substrate is integrated with an interface module connected with the head-mounted nerve recorder. According to the system, through the synergistic effect of magnetic guidance and the flexible substrate, the problem of minimally invasive implantation caused by insufficient mechanical strength of a hydrogel electrode is solved; the electrode can be accurately implanted into subcutaneous target tissue only through a small minimally invasive wound, the animal stress response and infection risk are remarkably reduced, and efficient connection with a head-mounted nerve recorder is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of biomedical engineering implantable neural electrodes, and in particular relates to a rodent subcutaneous magnetically guided minimally invasive hydrogel electrode system. Background Art

[0002] Implantable electrodes in rodents can achieve high signal-to-noise ratio neural signal acquisition and are the mainstream way to obtain high-precision neural signals. Traditional electromyographic electrodes are often made of materials such as metal, carbon fiber and conductive polymers, but their rigid structure is prone to tissue inflammation and requires implantation through large surgical incisions, which greatly increases the risk of postoperative infection. At the same time, this trauma can trigger a strong stress response in animals, causing the animal's endocrine system, nervous system, etc. to be in an abnormal state, affecting the reliability of experimental data. In recent years, hydrogel electrodes have become a research hotspot due to their excellent biocompatibility and soft properties, but their insufficient mechanical strength has led to major technical bottlenecks in minimally invasive implantation. At present, when using a head-mounted wireless neural recorder to collect signals, the success rate of conventional percutaneous implantation technology for hydrogel electrodes is low, which greatly limits its application in long-term in vivo monitoring and hindlimb muscle tissue monitoring. The development of new solutions is imminent.

[0003] After searching the prior art, it was found that Park J, Lee S, et al. of the Gwangju Institute of Science and Technology in South Korea wrote an article titled "Injectable Conductive Hydrogels with TunableDegradability as Novel Implantable Bioelectrodes" in Small 19.21(2023):2300250. The injectable conductive hydrogel (ICH) electrode developed by them showed excellent cell and tissue compatibility. Through experimental comparison, it was found that compared with traditional skin electrodes and injectable non-conductive hydrogel electrodes, ICH electrodes showed significant advantages in myoelectric signal acquisition. However, the key problem of injectable ICH electrodes in practical applications is that the wire of the electrode cannot be directly connected to the head-mounted neural recorder under the skin. If the skin connection method is adopted, the wire is easily broken due to scratching behavior when the mouse is in a free state, and the exposed interface is easily corroded by sweat, which seriously limits the long-term monitoring application.

[0004] Rao S, Huang S et al., Binghamton University, State University of New York, USA, wrote an article titled "Anisotropic Hydrogel Microelectrodes for Intraspinal Neural Recordings in vivo" in Research Square (2024): rs-3.rs-4693073. They made bioelectronic devices out of fibrous hydrogels and implanted them into wild-type and transgenic Thy1-ChR2-EYFP mice to record the myoelectric signals of muscles under anesthesia and free movement. The experiment showed that the hydrogel electrode can effectively record the electrical signals from ventral spinal cord neurons and tibialis anterior muscles simultaneously during optogenetic stimulation. In the free-moving electromyography (EMG) recording experiment, the interface device was subcutaneously connected from the animal's hind limbs to the skull and fixed. This experimental operation method has obvious disadvantages. Due to the large surgical incision area, the experimental animals will have a strong stress response, which is not only not conducive to the animal's physical recovery after surgery, but also reduces the accuracy and research value of the experimental results.

[0005] CN119097316A discloses a fully hydrogel neural electrode composed of four layers of hydrogel (PSFD hydrogel layer-LPPDMEAs layer-PSFD hydrogel layer-MHD layer), which can provide artificial electrical stimulation to the cerebral cortex of rats during epileptic seizures. However, due to the soft texture of the hydrogel material, when collecting signals with the help of a small animal head-mounted neural recorder, the electrode is easily deformed and broken due to the resistance of the subcutaneous tissue during the process of moving the electrode to the specified position. When implanted subcutaneously, it is difficult to accurately position it, which affects the accuracy and stability of signal acquisition.

[0006] In summary, when collecting electromyographic signals from the back or limbs of rodents, implantable hydrogel electrodes have problems such as large incisions during the implantation process, inability to directly connect to a head-mounted neural recorder, and high electrode breakage rate, which makes it difficult to locate the electrode. Summary of the invention

[0007] In view of the defects and gaps in the prior art, the purpose of the present invention is to provide a rodent subcutaneous magnetic-guided minimally invasive hydrogel electrode system, which can minimize the damage and stress to experimental animals by realizing precise and minimally invasive electrode implantation operations, significantly improve experimental efficiency and data quality, and provide a safe, reliable and efficient new technical solution for in-depth research in the field of biomedical engineering technology.

[0008] To achieve the above purpose, the technical solution provided by the present invention is:

[0009] Provided is a rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system, comprising a flexible electrode substrate-soft hydrogel electrode complex, a bipolar magnetic nail assembly and an interface module;

[0010] The bipolar magnetic nail assembly includes an implanted magnetic nail and an external magnet, and the attraction and repulsion between the two are switched by flipping the magnetic poles. The implanted magnetic nail is used to be inserted into the subcutaneous muscle tissue through a wound on the skin of a rodent, and the external magnet is used to interact with the implanted magnetic nail outside the animal's body, so as to guide the complex to be implanted at a target implantation position under the skin of the rodent based on the principle that like poles repel each other and opposite poles attract each other, to detach the implanted magnetic nail from the complex, and to remove the implanted magnetic nail from the same wound outside the body.

[0011] The flexible electrode substrate of the composite includes a base layer, a conductive metal layer and a packaging layer stacked in sequence. The soft hydrogel electrode of the composite is embedded in the packaging layer and adheres to the electrode point surface of the conductive metal layer. An opening is provided at one end of the flexible electrode substrate, and the implanted magnetic pin can be inserted into the opening. An interface module is integrated at the other end for connecting to a head-mounted neural recorder to wirelessly transmit the collected signals.

[0012] Furthermore, the structure of the implanted magnetic nail is T-shaped, and includes a transverse part and a longitudinal part that are attracted together due to different magnetic properties. It is made of neodymium iron boron permanent magnet material, and the surface is coated with a bio-inert Parylene coating. The magnetization direction is distributed along the axial direction; the external magnet is a rectangular neodymium iron boron magnet, and includes two magnets that are attracted together due to different magnetic properties, which can achieve a 180° flip of the magnetic pole direction.

[0013] Further, the longitudinal portion of the implanted magnetic pin is inserted into the composite, and the transverse portion is used to interact with an external magnet; or, the transverse portion of the implanted magnetic pin is semicircular, and the longitudinal portion is inserted into the composite and used to interact with an external magnet.

[0014] Furthermore, the size of the longitudinal part of the implanted magnetic nail is 1mm×1mm×3mm, the size of the transverse part is 3mm×1mm×1mm, the thickness of the Parylene coating is 5-10μm; the size of the external magnet is 2mm×2mm×4mm.

[0015] Furthermore, the soft hydrogel electrode is composited with a polyacrylamide matrix and carbon nanotubes.

[0016] Furthermore, the base layer and the packaging layer of the flexible electrode substrate are both polyimide films, and the conductive metal layer is a patterned copper foil.

[0017] Furthermore, the thickness of the polyimide film is 20-50 μm, and the thickness of the patterned copper foil is 50-100 μm.

[0018] Furthermore, the soft hydrogel electrode is bonded to the conductive metal layer of the flexible electrode substrate through the polydopamine adhesion layer.

[0019] Furthermore, the soft hydrogel electrode is prepared by the following process: acrylamide monomer, N,N'-methylenebisacrylamide crosslinker, carbon nanotubes and deionized water are mixed and ultrasonically dispersed; after nitrogen is injected for deoxygenation, ammonium persulfate initiator is added to obtain a hydrogel; after curing, the hydrogel is cut and bonded to the conductive metal layer through a polydopamine adhesion layer.

[0020] The advantages of the present invention are:

[0021] 1. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode system proposed in the present invention, when implanted, the implanted magnetic pin connected to the flexible electrode substrate is inserted into the minimally invasive opening on the animal's skin, and the flexible electrode substrate-soft hydrogel electrode complex is guided to the target implantation site by the interaction between the external magnet and the implanted magnetic pin. After the implantation is completed, the implanted magnetic pin can be separated from the complex by the interaction between the external magnet and the implanted magnetic pin, and then reversely guided through the original channel, and finally taken out of the body through the same minimally invasive opening. The present invention innovatively uses the magnet attraction and repulsion guidance system to accurately control the movement direction and position of the soft hydrogel electrode, ensuring that the electrode reaches the target position accurately, and effectively avoiding the problem that the traditional operation causes stress response and infection risk in animals due to excessive wounds, thereby affecting the experimental results. This not only greatly improves the success rate of hydrogel electrode implantation, but also significantly improves the accuracy of experimental data, providing a more reliable data basis for related research.

[0022] 2. The present invention combines a soft hydrogel electrode with a flexible electrode substrate, which not only makes the hydrogel electrode less likely to break during movement, ensuring that the electrode is successfully implanted subcutaneously and easy to position, but also the interface module can be directly connected to a head-mounted neural recorder to achieve signal acquisition. This not only utilizes the hydrogel electrode's low tissue irritation, but also solves the problem of being unable to be successfully implanted subcutaneously and being unable to directly connect to a head-mounted neural recorder due to insufficient mechanical strength, providing an effective solution for the long-term and stable acquisition of small animal neural signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or other features and advantages of the present invention will become more easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are exaggerated or reduced to show details of specific components. In the accompanying drawings:

[0024] Figure 1 The composition and implantation process of the rodent subcutaneous magnetic guided minimally invasive hydrogel electrode system of the present invention are schematically shown. Figure 1 ;

[0025] Figure 2It is a schematic structural diagram of the flexible electrode substrate-soft hydrogel electrode complex in the present invention;

[0026] Figure 3 It is a partial schematic diagram of the process of the rodent subcutaneous magnetic-guided minimally invasive hydrogel electrode implantation of the present invention;

[0027] Figure 4 The composition and implantation process of the rodent subcutaneous magnetic guided minimally invasive hydrogel electrode system of the present invention are schematically shown. Figure 2 ;

[0028] Figure 5 It is a schematic diagram of the rodent subcutaneous magnetic-guided minimally invasive hydrogel electrode system of the present invention for multi-channel minimally invasive hydrogel electrode implantation.

[0029] In the figure: 1-flexible electrode substrate-soft hydrogel electrode complex, 11-flexible electrode substrate, 111-base layer, 112-conductive metal layer, 113-packaging layer, 114-opening, 12-soft hydrogel electrode; 2-implanted magnetic pin; 3-external magnet; 4-interface module; 100-skin; 101-subcutaneous muscle tissue; 200-head-mounted neural recorder. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration, and is not intended to limit the present invention.

[0031] The present invention provides a rodent subcutaneous magnetically guided minimally invasive hydrogel electrode system, which cleverly solves the problem of minimally invasive implantation of hydrogel electrodes due to insufficient mechanical strength through the synergistic effect of magnetic guidance and flexible substrate, and has good tissue compatibility. At the same time, only a 5mm minimally invasive incision is required to accurately implant the electrode into the subcutaneous target tissue, significantly reducing the animal's stress response and infection risks, and achieving efficient connection with a head-mounted neural recorder, providing a reliable technical solution for long-term and stable acquisition of neural signals, which has very important practical value and innovative significance.

[0032] Reference Figure 1 As an exemplary embodiment of the present invention, the rodent subcutaneous magnetically guided minimally invasive implantable hydrogel electrode system includes a flexible electrode substrate-soft hydrogel electrode complex 1, a bipolar magnetic nail assembly and an interface module 4. The complex 1 includes a flexible electrode substrate 11 and a soft hydrogel electrode 12; the bipolar magnetic nail assembly includes an implanted magnetic nail 2 and an external magnet 3, and the attraction and repulsion between the two can be switched by flipping the magnetic poles; the interface module 4 is used to connect to a head-mounted neural recorder 200 compatible with a wireless transmission protocol to wirelessly transmit the collected signals.

[0033] The implantable magnetic pin 2 is used to be inserted into the subcutaneous muscle tissue 101 through the wound on the rodent skin 100, and the external magnet 3 is used to interact with the implantable magnetic pin 2 outside the animal body, so as to guide the complex 1 to be implanted into the target implantation position under the rodent skin based on the principle that like charges repel and opposite charges attract between magnets, to detach the implantable magnetic pin 2 from the complex 1, and to remove the implantable magnetic pin 2 from the body through the same wound.

[0034] In the embodiment shown, the structure of the implanted magnetic nail 2 is T-shaped, and includes a transverse part and a longitudinal part that are attracted together due to different magnetic properties, and is made of NdFeB permanent magnet material, with a biologically inert Parylene coating on the surface, and the magnetization direction is distributed along the axial direction; the external magnet 3 is a rectangular NdFeB magnet, and includes two magnets that are attracted together due to different magnetic properties, and can achieve a 180° flip of the magnetic pole direction. It should be understood that the longitudinal part refers to the part of the magnetic nail inserted into the composite 1, and the transverse part refers to the part perpendicularly connected to the part.

[0035] In this embodiment, the longitudinal portion of the implanted magnetic pin 2 is inserted into the composite body 1, and the transverse portion is used to interact with the external magnet 3. However, the structure of the implanted magnetic pin 2 is not limited thereto. Figure 4 Described.

[0036] According to the present invention, the size of the longitudinal part of the implanted magnetic nail 2 is 1mm×1mm×3mm (length×width×height), the size of the transverse part is 3mm×1mm×1mm (length×width×height), the total height of the magnetic nail is 4mm, and the thickness of the Parylene coating is 5-10μm; the size of the external magnet 3 is 2mm×2mm×4mm (length×width×height) to ensure that the magnetic interaction between the magnetic nail and the magnet can guide the electrode and separate the magnetic nail from the electrode.

[0037] Reference Figure 2 The flexible electrode substrate 11 of the composite 1 includes a base layer 111, a conductive metal layer 112 and an encapsulation layer 113 stacked in sequence. The soft hydrogel electrode 12 of the composite 1 is embedded in the encapsulation layer 113 and adhered to the electrode point surface of the conductive metal layer. The flexible electrode substrate 11 can provide mechanical support for the soft hydrogel electrode 12. An opening 114 is provided at one end of the flexible electrode substrate, and the implanted magnetic pin 2 can be inserted into the opening 114. The size of the opening can be 2mm×2mm, which is larger than the bottom of the longitudinal part of the implanted magnetic pin 2, so as to facilitate the smooth removal of the magnetic pin. The other end is integrated with an interface module 4, which can be directly connected to a head-mounted neural recorder, and the signal is wirelessly transmitted to the PC. The wireless neural recording system of the interface module 4 can realize wireless acquisition and transmission of signals to the PC, and the sampling rate can be 500Hz.

[0038] In some embodiments, the base layer 111 and the encapsulation layer 113 of the flexible electrode substrate 11 are both polyimide films, the conductive metal layer 112 is a patterned copper foil, and a trace is formed by a photolithography process, the trace width can be 3 mm, and the trace length can be adjusted according to actual needs. The thickness of the polyimide film is 20-50 μm, and the thickness of the patterned copper foil is 50-100 μm.

[0039] The soft hydrogel electrode 12 can be composed of a composite of a polyacrylamide matrix and carbon nanotubes, with a thickness of 50-100 μm, a conductivity of ≥10S / m, an adhesion strength of ≥50 kPa, and is evenly coated on the electrode point surface of the conductive metal layer, having both biocompatibility and high conductivity.

[0040] Preferably, the soft hydrogel electrode 12 is prepared by the following process: acrylamide monomer, N,N'-methylenebisacrylamide crosslinker, carbon nanotubes and deionized water are mixed and ultrasonically dispersed; after nitrogen is injected for deoxygenation, ammonium persulfate initiator is added to obtain a hydrogel; after curing, the hydrogel is cut and bonded to the conductive metal layer through the polydopamine adhesion layer. More specifically, 15wt% of acrylamide monomer, 0.1wt% of N,N'-methylenebisacrylamide crosslinker, and 3wt% of carbon nanotubes can be mixed with deionized water and ultrasonically dispersed for 30 minutes; after nitrogen is injected for deoxygenation, 0.5wt% of ammonium persulfate initiator is added and cured at 60°C for 1 hour; the cured hydrogel is cut into squares with a side length of 3mm and bonded to the conductive metal layer through the polydopamine adhesion layer.

[0041] Reference Figure 3 , the implantation process of the hydrogel electrode of the present invention is described:

[0042] The first step is to prepare a flexible electrode substrate-soft hydrogel electrode complex 1, wherein an opening 114 is designed at one end of the flexible electrode substrate 11 to connect the implanted magnetic pin 2, and the other end is designed as an interface module 4 for external connection. A soft hydrogel electrode 12 is coated on the electrode point and bonded to the conductive metal layer through a polydopamine adhesion layer. During this period, the amount of hydrogel is controlled to ensure good adhesion without overflowing due to excessive amount and affecting other parts. During the implantation process, ensure that the side of the electrode point faces the muscle to smoothly collect signals;

[0043] The second step is to use isoflurane gas anesthesia to place the animal in an anesthesia box. After it is anesthetized, it is transferred to the operating table and anesthesia is maintained continuously to ensure that it is in a deep anesthesia state during the operation and its vital signs are stable. Subsequently, the hair on the animal's head is removed and the head skin is disinfected with iodine tincture. The disinfection range is a circular area with a diameter of about 3 cm to ensure thorough disinfection and no microorganisms remain. An animal scalpel is used to make a 5 mm long suture wound on the skin.

[0044] The third step is to put the implanted magnetic pin 2 on the opening 114 at one end of the pre-prepared flexible electrode substrate-soft hydrogel electrode complex 1, and slowly insert it and the complex through the wound into the subcutaneous muscle tissue; at this time, the external magnet 3 is accurately placed about 1-2 cm from the skin surface near the wound, and the direction and angle of the external magnet 3 are adjusted according to the magnetic pole distribution characteristics of the implanted magnetic pin 2 and the external magnet 3, and the repulsive force between the magnets is cleverly used to push the soft hydrogel electrode 12 close to the subcutaneous muscle tissue, so that it moves steadily toward the preset target position; during the movement process, the movement trajectory and position change of the electrode are continuously observed to ensure that the electrode is accurately pushed toward the target area. During the movement of the electrode, since the soft hydrogel electrode is combined with the flexible electrode substrate, the hydrogel electrode is not easy to break during the movement process, which can ensure that the electrode is successfully implanted subcutaneously;

[0045] In the fourth step, when the soft hydrogel electrode 12 successfully reaches the designated position, carefully flip the external magnet 3, use the attraction between the magnets to slowly pull the implanted magnetic nail 2 out of the flexible electrode substrate 11, and then slowly move the external magnet 3 to the wound, use the repulsive force between it and the implanted magnetic nail 2 to guide it in the reverse direction through the original channel, completely remove the implanted magnetic nail 2, and then use medical sutures to accurately suture the wound, and evenly apply an appropriate amount of antibiotic ointment on the surface of the wound to effectively prevent postoperative infection. It should be understood that during and after the implantation process, the interface module 4 is always located outside the animal body. After the implantation is completed, the head-mounted neural recorder can be plugged into the interface module 4.

[0046] Reference Figure 4 In another embodiment of the present invention, in order to achieve the same implantation effect, the implanted magnetic nail 2 is innovatively replaced and optimized, and the transverse part of the implanted magnetic nail 2 is processed into a semicircular shape, and the longitudinal part is inserted into the complex 1 and used to interact with the external magnet 3. This unique semicircular structure design can effectively reduce the resistance encountered by the implanted magnetic nail during movement, laying a good foundation for subsequent minimally invasive implantation and precise positioning.

[0047] During the critical stage of minimally invasive electrode implantation, the operation steps are as follows: Flip the implanted magnetic pin 2 180 degrees, with one end of the semicircle facing downward, and then smoothly pass through the bottom of the complex 1; then use the attraction between the magnetic fields as a driving force to pull the electrode along the preset path to the specified position until it reaches the target site accurately. Compared with the previous implantation method, this design significantly reduces the risk of accidental separation of the electrode and the magnetic pin during the implantation process, and greatly improves the stability and reliability of the implantation operation.

[0048] The process of minimally invasive removal of magnetic pins: first, flip the external magnet 3, and use the repulsive force between the magnetic fields to make the implanted magnetic pin 2 detach from the opening 114 on the complex 1; at the moment the magnetic pin is detached from the hole, quickly move the implanted magnetic pin 2 slightly in the opposite direction of the complex 1, and the complex 1 will fall on the subcutaneous muscle tissue under the action of gravity; after completing this step, flip the external magnet 3 again, and use the attractive force between the magnetic fields to bring the implanted magnetic pin 2 out of the body intact and safely, thereby successfully completing the entire minimally invasive implantation and removal operation process.

[0049] Reference Figure 5 , the rodent subcutaneous magnetic-guided minimally invasive hydrogel electrode system proposed in the present invention demonstrates excellent flexibility and wide applicability. The implantation location of complex 1 is no longer limited to the traditional back area, and its application range has been successfully expanded to the muscles of the limbs, opening up a new way to obtain more comprehensive and accurate bioelectric signals. Based on the core technical principles of the present invention, using the force between magnetic fields, combined with the uniquely designed complex 1 and two matching sets of small magnets, this innovative method can play a key role in both experimental studies that need to monitor changes in bioelectric activity during limb muscle movement, and in the precise diagnosis and treatment exploration of specific neuromuscular disease models.

[0050] Specifically, when performing electrode implantation operations in limb muscles, first of all, the experimental animals are accurately anesthetized and the surgical area is disinfected in accordance with strict experimental specifications. Taking implantation into the hind limb muscles as an example, after confirming the implantation site, the complex 1 connected to the implanted magnetic pin 2 is gently inserted into the subcutaneous tissue through a very small skin wound. At this time, the external magnet 3 plays a key role. According to the magnetic pole characteristics of the micro-implanted magnetic pin 2 and the external magnet 3, the direction and angle of the external magnet 3 are adjusted, and the repulsive force between the magnetic fields is used to guide the complex 1 along the planned path, close to the subcutaneous muscle tissue and move toward the target position. When the complex 1 successfully reaches the predetermined position, the external magnet 4 is flipped, and the attraction between the magnetic fields is used to smoothly separate the implanted magnetic pin 2 from the complex 1 under the action of gravity. After being taken out in reverse through the original channel, the wound is closed with medical sutures and antibacterial treatment is applied, while the complex 1 is left at the target muscle position to collect muscle electrical signals.

[0051] Therefore, as described above, the present invention innovatively uses a magnetic attraction and repulsion guidance system to accurately control the moving direction and position of the soft hydrogel electrode, ensuring that the electrode accurately reaches the target position, effectively avoiding the problem of traditional operations causing stress reactions and infection risks in animals due to excessive wounds, thereby affecting the experimental results. In addition, the present invention combines the soft hydrogel electrode with a flexible electrode substrate, which not only makes the hydrogel electrode less likely to break during movement, but also ensures that the electrode is successfully implanted under the skin and easy to position, and the interface module can be directly connected to the head-mounted neural recorder to achieve signal acquisition.

[0052] Finally, it should be noted that the features mentioned and / or shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present invention.

Claims

1. A rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system, characterized in that: It includes a flexible electrode substrate-soft hydrogel electrode complex, a bipolar magnetic pin assembly and an interface module; The bipolar magnetic nail assembly includes an implanted magnetic nail and an external magnet, and the attraction and repulsion between the two are switched by flipping the magnetic poles. The implanted magnetic nail is used to be inserted into the subcutaneous muscle tissue through a wound on the skin of a rodent, and the external magnet is used to interact with the implanted magnetic nail outside the animal body, so as to guide the complex to be implanted in the rodent's subcutaneous target implantation position based on the principle that like poles repel and opposite poles attract, so that the implanted magnetic nail is separated from the complex, and the implanted magnetic nail is taken out of the body from the same wound; The flexible electrode substrate of the composite body comprises a base layer, a conductive metal layer and a packaging layer stacked in sequence, and the soft hydrogel electrode of the composite body is embedded in the packaging layer and adhered to the electrode point surface of the conductive metal layer; an opening is provided at one end of the flexible electrode substrate, and the implanted magnetic pin can be inserted into the opening, and the interface module is integrated at the other end for connecting to a head-mounted neural recorder to wirelessly transmit the collected signals.

2. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode system according to claim 1, characterized in that: The structure of the implanted magnetic nail is T-shaped, and includes a transverse part and a longitudinal part that are attracted together due to different magnetic properties. It is made of neodymium iron boron permanent magnet material, and the surface is coated with a bio-inert Parylene coating. The magnetization direction is distributed along the axial direction; the external magnet is a rectangular neodymium iron boron magnet, and includes two magnets that are attracted together due to different magnetic properties, which can achieve a 180° flip of the magnetic pole direction.

3. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 2, characterized in that: The longitudinal portion of the implanted magnetic pin is inserted into the complex, and the transverse portion is used to interact with the external magnet; or, the transverse portion of the implanted magnetic pin is semicircular, and the longitudinal portion is inserted into the complex and used to interact with the external magnet.

4. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 2 or 3, characterized in that: The size of the longitudinal part of the implanted magnetic nail is 1mm×1mm×3mm, the size of the transverse part is 3mm×1mm×1mm, and the thickness of the Parylene coating is 5-10μm; the size of the external magnet is 2mm×2mm×4mm.

5. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 1 or 2, characterized in that: The soft hydrogel electrode is composited by a polyacrylamide matrix and carbon nanotubes.

6. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode system according to claim 1 or 2, characterized in that: The base layer and the packaging layer of the flexible electrode substrate are both polyimide films, and the conductive metal layer is a patterned copper foil.

7. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 6, characterized in that: The thickness of the polyimide film is 20-50 μm, and the thickness of the patterned copper foil is 50-100 μm.

8. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 1 or 2, characterized in that: The soft hydrogel electrode is bonded to the conductive metal layer of the flexible electrode substrate through a polydopamine adhesion layer.

9. The rodent subcutaneous magnetically guided minimally invasive hydrogel electrode implantation system according to claim 1 or 2, characterized in that: The soft hydrogel electrode is prepared by the following process: acrylamide monomer, N,N'-methylenebisacrylamide crosslinking agent, carbon nanotubes and deionized water are mixed and ultrasonically dispersed; after nitrogen is injected for deoxygenation, ammonium persulfate initiator is added to obtain a hydrogel; after curing, the hydrogel is cut and bonded to a conductive metal layer through a polydopamine adhesion layer.

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