Bidirectional twisted-pair array brain electrode and preparation method thereof

Abstract

The invention relates to a bidirectional twisted-pair array brain electrode and a preparation method thereof.The twisted-pair electrode comprises a PVA electrode stem and a twisted-pair electrode wire formed by winding two single electrode wires, the twisted-pair electrode wire is arranged in the PVA electrode stem, and the front end of the twisted-pair electrode wire is exposed out of the front end of the PVA electrode stem; one single electrode wire exposed out of the front end of the twisted-pair electrode wire is provided with a contact site formed by removing an insulating layer, the other single electrode wire is not provided with a contact site, a circuit board is arranged in the electrode mounting seat, and one side, far away from the front end of the twisted-pair electrode, of the circuit board is provided with a plurality of electrode connecting terminals. The PVA electrode stems are arranged in the electrode mounting base in an array mode, and the single electrode wires exposed out of the rear ends of the PVA electrode stems are electrically connected with the corresponding electrode connecting terminals respectively. According to the invention, the bidirectional functions of multi-point electroencephalogram signal acquisition and electrical stimulation can be realized, and the requirements of miniaturization, safety, biological tissue compatibility and the like of large-scale and multi-channel arrangement of the brain electrode array can be met.

Description

Technical Field

[0001] The present invention relates to the field of brain-computer interface electrodes, and in particular to a bidirectional double-twisted array brain electrode and a preparation method thereof. Background Art

[0002] The main function of brain-computer interface is to interpret signals from specific areas of the brain and study the brain's operating mechanisms by collecting and analyzing relevant EEG signals or stimulating specific nerve cell structures.

[0003] Traditional non-invasive wearable brain electrodes have been widely used in the field of brain science due to their advantages such as non-invasiveness, convenience, and safety. Such electrodes are easy to wear and only need to be placed on the scalp outside the target brain area to collect EEG signals. However, such brain electrodes have certain defects. For example, they are not in direct contact with the actual brain tissue, which causes signal distortion. At the same time, because the electrodes are distributed on the surface of the scalp, the collected signals cannot reflect the deep-level information and operating mechanisms of the brain area. In addition, non-invasive brain electrodes have low resolution and are easily affected by the electrooculogram, electromyography, and shaking of the subjects or experimental animals. The data needs to be screened and denoised in a complicated process. Moreover, non-invasive electrodes can only realize the one-way EEG signal collection function and cannot realize the reverse function of electrically stimulating brain cells.

[0004] To solve the above problems, invasive brain electrodes came into being. Brain electrodes are implanted or attached to brain tissue or the inside of the skull through craniotomy or minimally invasive surgery, thereby achieving close contact with the brain tissue, greatly improving the accuracy and quality of the signal. At the same time, since the implantation depth can be controlled, signal measurement of deep brain tissue can be achieved, thereby improving the spatial resolution of EEG signals. In addition, since it is in direct contact with the brain tissue, it is possible to stimulate specific brain tissue by applying weak current or voltage to the electrodes, which is of great significance for studying the operating mechanism of brain networks.

[0005] Invasive multi-channel EEG electrodes can accurately interact with cerebral cortical activity, providing a foundation for physiological and neurological research. They also facilitate future analysis of multi-brain region coupling and intention recognition control. However, because invasive EEG electrodes are typically implanted surgically, they are relatively small and require complex processing techniques. Furthermore, concerns about biocompatibility and postoperative infection must be addressed, making the deployment of large-scale, multi-channel electrode arrays challenging.

[0006] Patent CN102323857B discloses a brain-computer interface electrode cap based on an elastic array, which includes a flexible electrode cap body with multiple input terminals provided therein, but the device is a non-invasive wearable structure. Patent CN111772630B discloses a brain-computer interface with a gel microneedle brain electrode, which includes a microneedle electrode, and each microneedle electrode includes multiple microneedles and a flexible patch, the microneedle includes a gel electrolyte and a columnar electrode, and the columnar electrode passes through the interior of the gel electrolyte and is exposed from the tip of the microneedle, the microneedle also includes a hollow conical, sticky biomimetic material outer layer, the gel electrolyte is arranged in the biomimetic material outer layer and can extend from the tip of the biomimetic material outer layer, so that the entire microneedle is also conical as a whole, and the flexible patch includes a first flexible substrate and a second flexible substrate, but the design purpose of the device is mainly to reduce impedance so as to be able to quickly and accurately collect brain telecommunications. Summary of the Invention

[0007] The purpose of the present invention is to provide a bidirectional twisted-pair array EEG electrode and its preparation method, which can realize the bidirectional functions of multi-point EEG signal acquisition and electrical stimulation, and can meet the requirements of miniaturization, safety, and biological tissue compatibility of large-scale and multi-channel arrangement of EEG electrode arrays.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] A bidirectional double-twisted array brain electrode comprises a double-twisted electrode and an electrode mounting seat, wherein the double-twisted electrode comprises a PVA electrode rod and a double-twisted electrode wire formed by winding two single electrode wires, wherein the double-twisted electrode wire is arranged in the PVA electrode rod and the front end is exposed from the front end of the PVA electrode rod, a single electrode wire exposed at the front end of the double-twisted electrode wire is provided with a contact site formed by removing the insulating layer, and the other single electrode wire is not provided with a contact site, a circuit board is provided in the electrode mounting seat, and a plurality of electrode connection terminals are provided on the side of the circuit board away from the front end of the double-twisted electrode, the PVA electrode rods are arranged in an array form in the electrode mounting seat, and the single electrode wires exposed at the rear end of the PVA electrode rod are electrically connected to the corresponding electrode connection terminals respectively.

[0010] The electrode mounting seat is formed by coating the twisted electrode array with biological glue and then solidifying it.

[0011] The biological glue is n-butyl cyanoacrylate adhesive.

[0012] A front end section of the PVA electrode rod extends from the electrode mounting seat to form an implantation section, and an exposed twisted pair electrode wire is provided at the front end of the implantation section.

[0013] The side of the electrode mounting seat away from the front end of the twisted pair electrode is connected to the front end of an electrode extension seat. The rear end of the electrode extension seat is provided with multiple interface pins, and each electrode connection terminal is electrically connected to the corresponding interface pin.

[0014] The electrode extension seat is in a cone shape with a thin front and a thick back, wherein the thin-diameter end of the electrode extension seat is fixedly connected to the electrode mounting seat, and the thick-diameter end of the electrode extension seat is provided with a plurality of interface pins in an array form.

[0015] A method for preparing the bidirectional double-twisted array EEG electrode comprises the following steps:

[0016] Step 1: twist two single electrode wires to form a twisted pair of electrode wires;

[0017] Step 2: etching away a predetermined number of insulating layers on the surface of one of the single electrode wires at the front end of the twisted pair of electrode wires, which faces the other single electrode wire, to form contact points;

[0018] Step 3: applying a photoresist layer of a set thickness on the surface of the resin base plate to form a base plate, and then etching the base plate to form grooves;

[0019] Step 4: Filling the PVA solution into the groove;

[0020] Step 5: Soaking the twisted pair electrode wires in the PVA solution in the groove, and baking to solidify the PVA to form a primary twisted pair electrode;

[0021] Step 6: Combine the primary twisted pair electrodes into an array;

[0022] Step 7: Soak both ends of the primary twisted pair electrode array in water to remove the PVA material and form the final twisted pair electrode array;

[0023] Step 8: Untwist the exposed twisted electrode wires at the end of the twisted electrode array, and use the single electrode wire with the contact site as the positive electrode and the other electrode wire as the negative electrode;

[0024] Step 9: Weld the positive electrode and the negative electrode to the corresponding electrical points on the circuit board, and the electrical points are electrically connected to the electrode connection terminals on the other side;

[0025] Step 10: Use biological glue to cover the twisted electrode array and solidify it to form an electrode mounting base.

[0026] In step 2, the insulating layer is etched using femtosecond laser technology to form contact sites, and in step 3, the bottom plate is etched using a photolithography machine to form grooves.

[0027] In step six, the primary twisted pair electrodes are arranged in parallel in an array form, and the set positions of two adjacent primary twisted pair electrodes are bonded and fixed using biological glue. The set length area with the contact site at the front end of the primary twisted pair electrode and the set length area at the end of the primary twisted pair electrode are not bonded.

[0028] In step seven, the set length area at the front end of the primary twisted electrode array that is not bonded is immersed in water for a set time to expose all contact points, and the set length area at the rear end of the primary twisted electrode array that is not bonded is immersed in water for a set time to expose the set length of the twisted electrode wire.

[0029] The advantages and positive effects of the present invention are:

[0030] 1. The present invention adopts a twisted pair electrode wire structure to realize the bidirectional function of EEG signal acquisition and electrical stimulation, wherein a single electrode wire with multiple contact points with the insulation layer removed at the front end of the twisted pair electrode wire is the positive electrode, and the other single electrode wire is the negative electrode, and the multiple contact points can realize multi-point EEG signal acquisition and electrical stimulation. In addition, the present invention uses PVA electrode rods to realize array assembly, which can realize large-scale, multi-channel electrode array arrangement while meeting miniaturization requirements.

[0031] 2. The present invention utilizes maskless photolithography technology to produce a base plate to form grooves, and places a PVA solution and twisted electrode wires in the grooves, which are then baked and solidified to form PVA electrode rods to facilitate the subsequent array combination of twisted electrodes. In addition, the PVA material is a completely non-toxic material and will not produce toxic substances when implanted in the human body for a long time, thus meeting the safety requirements for use.

[0032] 3. Due to the water solubility of PVA in the present invention, the PVA material at both ends of the PVA electrode rod can be removed by immersing in water to expose a set length of twisted electrode wire. On the one hand, this can ensure that all contact points at the front end of the twisted electrode wire are fully exposed, and on the other hand, it can ensure that the rear end of the twisted electrode wire can be exposed to a sufficient length to meet the subsequent welding needs with the circuit board. At the same time, the preparation and assembly are also relatively convenient.

[0033] 4. The present invention uses biological glue to wrap the twisted electrode array and form an electrode mounting seat, which can further ensure that the present invention meets the requirements of large-scale, multi-channel arrangement and miniaturization of the electrode array. At the same time, the biological glue can be a medical adhesive such as cyanoacrylate adhesive, which has good adhesion and high compatibility with biological tissues, and can meet the requirements of biocompatibility and safety.

[0034] 5. The present invention utilizes an electrode extension seat to connect with an electrode mounting seat, which facilitates the connection between the present invention and related equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1It is a structural schematic diagram of the present invention,

[0036] Figure 2 for Figure 1 The enlarged view of point A in the figure,

[0037] Figure 3 for Figure 2 Schematic diagram of the structure of the twisted pair electrode.

[0038] Figure 4 for Figure 3 The enlarged view of point B in the figure is as follows:

[0039] Figure 5 is a schematic flow diagram of the preparation method of the present invention,

[0040] Figure 6 This is a schematic diagram of signals collected in an application example of the present invention.

[0041] Among them, 1 is a twisted pair electrode, 101 is a twisted pair electrode wire, 1011 is a contact site, 102 is a PVA electrode rod, 2 is an electrode mounting base, 201 is a circuit board, 202 is biological glue, 203 is an electrode connection terminal, 3 is an electrode extension base, and 301 is an interface pin. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figures 1 to 6 As shown, the present invention comprises a twisted pair electrode 1, an electrode mounting base 2 and an electrode extension base 3 connected in sequence, wherein Figures 3-4 As shown, the twisted electrode 1 includes a twisted electrode wire 101 and a PVA electrode rod 102. The twisted electrode wire 101 is arranged in the PVA electrode rod 102, and the front end of the twisted electrode wire 101 is exposed from the front end of the PVA electrode rod 102. Figure 2 As shown, a circuit board 201 is provided in the electrode mounting seat 2, and a plurality of electrode connection terminals 203 are provided on the side of the circuit board 201 away from the front end of the twisted electrode 1. The PVA electrode rods 102 are arranged in an array in the electrode mounting seat 2, and the rear ends of the PVA electrode rods 102 are electrically connected to the corresponding electrode connection terminals 203 respectively. The rear end of the electrode extension seat 3 is provided with a plurality of interface pins 301, and the electrode connection terminals 203 are electrically connected to the corresponding interface pins 301 respectively.

[0044] like Figures 3-4As shown, in this embodiment, a nickel-chromium alloy wire with a diameter of 80 μm is coated with a 20 μm polyimide (PI) insulating coating (insulating layer) to form a composite metal wire material with a diameter of 100 μm as the electrode material, that is, a single electrode wire. Then, two single electrode wires with a length of 20 mm are aligned at both ends and then twisted to form the twisted pair electrode wire 101. During the twisting, one end of the two parallel aligned single electrode wires rotates in a clockwise direction and the other end rotates in a counterclockwise direction, thereby forming a twisted pair electrode wire 101. Figure 4 The twisted pair electrode wire 101 structure shown, after winding is completed, the present invention uses femtosecond laser processing technology to evenly etch away the insulation layer at four points along the length direction of the single electrode wire on the surface of a single electrode wire facing the other single electrode wire in the front end of the twisted pair electrode wire 101, so that a total of five exposed contact sites 1011 without insulation layer and spaced from each other are formed, including the front end of this single electrode wire. The five contact sites 1011 are formed within the 1mm area of ​​the front end of the twisted pair electrode wire 101, which can contact the brain tissue and collect electrical signals, thereby realizing multi-point EEG signal collection and electrical stimulation. In this embodiment, the center distance between each two adjacent contact sites 1011 is 200μm, and the diameter of each contact site 1011 is 10μm. In addition, the femtosecond laser processing technology is a well-known technology in the field.

[0045] like Figures 3-4 As shown, in this embodiment, the PVA electrode rods 102 are fabricated by first applying a 300μm thick photoresist layer evenly to the surface of a resin substrate. Then, using maskless photolithography, a groove with a depth x width x length of 300μm x 300μm x 20mm is uniformly etched in the photoresist layer. A 50wt% PVA (polyvinyl alcohol) solution is then filled into the groove, followed by the placement of the twisted pair electrode wires 101. The twisted pair electrode wires 101 placed in the grooves must be completely immersed in the PVA solution. Excess PVA solution outside the grooves is then removed, and the PVA is cured using a baking machine at 80°C. After curing, the twisted pair electrode wires 101 coated with the PVA layer are removed to form a primary twisted pair electrode. The cured PVA layer forms the PVA electrode rods 102. The PVA layer can be further processed into a suitable shape, such as a round rod, as needed to ensure that each PVA electrode rod 102 has a consistent shape. Both the maskless photolithography technique and the baking machine are well known in the art.

[0046] Since PVA material is readily soluble in water, the present invention utilizes a water soaking method to remove the PVA material coating the ends of the primary twisted pair electrodes, exposing the twisted electrode wires 101 at both ends of the primary twisted pair electrodes, thereby forming the final twisted pair electrodes 1. In this embodiment, a 1 mm long area at the front end of the primary twisted pair electrodes is soaked in water for 15 minutes, thereby exposing the five contact sites 1011 distributed within the 1 mm area at the front end of the electrodes. The 5 mm long area at the rear end of the primary twisted pair electrodes is then soaked in water for another 15 minutes, thereby exposing the 5 mm long electrode wires at the rear end of the electrodes. The single electrode wire with the five contact sites 1011 serves as the positive electrode, and the other electrode wire serves as the negative electrode. The positive and negative electrodes are welded to corresponding electrical points on the circuit board 201 near the front end of the twisted pair electrodes 1, thereby achieving connection between the twisted pair electrodes 1 and the circuit board 201. These electrical points are electrically connected to the electrode connection terminals 203 on the side of the circuit board 201 away from the front end of the twisted pair electrodes 1.

[0047] In this embodiment, the circuit board 201 is a PCB circuit board, and the electrode connection terminal 203 is a 1.27 mm standard electrical interface. In addition, due to the poor biocompatibility of the PCB circuit board, in this embodiment, a layer of cyanoacrylate n-butyl adhesive (thickness 0.1 mm) is applied to the outer surface of the circuit board 201 to achieve bonding and fixing. This ensures reliable connection while also improving biocompatibility.

[0048] like Figure 2 As shown, the electrode mounting base 2 is formed by solidifying the twisted electrode array 1 after covering it with biological glue 202. In this embodiment, the biological glue can be a cyanoacrylate n-butyl adhesive used to cover the twisted electrode array 1. The adhesive has good adhesion and high compatibility with biological tissues, and can meet the requirements of biocompatibility and safety. In addition, PVA material is a completely non-toxic material and will not produce toxic substances when implanted in the human body for a long time, thus meeting the safety requirements of use.

[0049] like Figure 2 As shown, in this embodiment, a front end section of the PVA electrode rod 102 extends from the electrode mounting base 2 to form an implantation section, and an exposed twisted pair of electrode wires 101 is provided at the front end of the implantation section. The implantation section contacts the brain tissue, and the PVA coating of the twisted pair of electrode wires 101 is not removed. This allows the PVA in the implantation section to gradually melt during implantation using the moisture in the brain tissue, exposing the longer twisted pair of electrode wires 101, thereby ensuring that the twisted pair of electrode wires 101 can ultimately penetrate vertically into the target brain region.

[0050] like Figure 1As shown, in this embodiment, the electrode extension seat 3 is in a conical shape with a thin front and a thick back, wherein the thin-diameter end of the electrode extension seat 3 is fixedly connected to the electrode mounting seat 2, and the thick-diameter end of the electrode extension seat 3 is provided with a plurality of interface pins 301 in an array form. A plurality of wire channels can be set inside the electrode extension seat 3 as needed, and the wires used to connect the electrode connection terminal 203 and the interface pins 301 are respectively provided in the corresponding wire channels.

[0051] The working principle of the present invention is:

[0052] like Figure 5 As shown, the preparation method of the present invention comprises the following steps:

[0053] Step 1: Two single electrode wires of the same length are twisted together to form a twisted pair of electrode wires 101. During the twisting process, one end of the two parallel aligned single electrode wires is rotated in a clockwise direction and the other end is rotated in a counterclockwise direction.

[0054] Step 2: Using femtosecond laser technology, a predetermined number of insulating layers are etched away along the length direction of the single electrode wires on the surface of the front end of the twisted pair of electrode wires 101 facing the other single electrode wire to form contact sites 1011 .

[0055] In this embodiment, on the surface of a single electrode wire facing the other single electrode wire at the front end of the twisted pair of electrode wires 101, the insulation layer is uniformly etched away at four points along the length direction of the single electrode wire, so that a total of five exposed contact points 1011 that are spaced apart from each other and have no insulation layer are formed, including the front end of this single electrode wire.

[0056] Step 3: Apply a photoresist layer of a set thickness on the upper surface of the resin base to form a base plate, and then use a photolithography machine to etch the base plate to form grooves.

[0057] In this embodiment, a photoresist layer with a thickness of 300 μm is evenly coated on the resin substrate, and then a groove with a depth×width×length of 300 μm×300 μm×20 mm is evenly etched on the photoresist layer using a photolithography machine and maskless photolithography technology.

[0058] Step 4: Fill the groove with PVA (polyvinyl alcohol) solution.

[0059] In this embodiment, a 50 wt % PVA (polyvinyl alcohol) solution is filled into the groove, and the groove is completely filled.

[0060] Step 5: Soak the twisted pair electrode wire 101 in a PVA solution and bake to solidify the PVA to form a primary twisted pair electrode.

[0061] In this embodiment, a baking device is used to bake at 80 degrees Celsius to solidify the PVA.

[0062] Step 6: Combine the primary twisted pair electrodes into an array.

[0063] In this embodiment, 36 20mm long primary twisted pair electrodes were arranged in parallel in a square array. Two adjacent primary twisted pair electrodes were bonded together from 1mm to 15mm from the front end using n-butyl cyanoacrylate adhesive. The 1mm front end of the primary twisted pair electrodes, which contained contact sites 1011, and the 5mm end were not bonded using n-butyl cyanoacrylate adhesive. The n-butyl cyanoacrylate adhesive is a medical adhesive known as n-butyl α-cyanoacrylate adhesive, and was manufactured by 3M China Ltd. in this embodiment.

[0064] Step 7: Soak both ends of the primary twisted pair electrode array in water to remove the PVA material and form the final twisted pair electrode 1 array.

[0065] In this embodiment, a 1 mm long area at the front end of the primary twisted pair electrode array is immersed in water for 15 minutes, thereby exposing the five contact sites 1011 distributed within the 1 mm area at the front end of the electrode. Then, a 5 mm long area at the rear end of the primary twisted pair electrode array is immersed in water for 15 minutes, thereby exposing the 5 mm long twisted pair electrode wire 101.

[0066] Step 8: Untwist the exposed twisted electrode wires 101 at the ends of the twisted electrode array 1. In any untwisted set of twisted electrode wires 101, the single electrode wire with five contact sites 1011 is the positive electrode, and the other electrode wire is the negative electrode.

[0067] Step nine: Weld the positive and negative electrodes to corresponding electrical points on the circuit board 201 , respectively. The electrical points are electrically connected to the electrode connection terminals 203 on the side of the circuit board 201 away from the front end of the twisted pair electrode 1 .

[0068] Step 10: Use biological glue 202 to cover the twisted electrode 1 array and solidify to form an electrode mounting base 2, and then connect the electrode mounting base 2 to the electrode extension base 3.

[0069] An application example is listed below to further illustrate the operating principle of the present invention.

[0070] Application example 1:

[0071] In this application example, rats are used as the subjects, and the usage process is as follows:

[0072] 1. The rat's head area must be pre-treated before use, including skin preparation, disinfection, skin removal, and skull exposure.

[0073] Second, use a skull drill to open a 2mm×2mm window in the skull above the visual cortex of the rat, remove the cerebrospinal fluid, and expose the visual cortex of the brain.

[0074] 3. Insert twisted pair electrode 101 vertically into the rat's visual cortex along the cranial window to a depth of 1 mm, until the tip of twisted pair electrode wire 101 with contact site 1011 (exposure site) is completely inserted into the brain. During insertion, positioning can be coordinated using a small animal brain locator, a commercially available product manufactured by Shenzhen Ruiwode Life Science Co., Ltd. (in this application example).

[0075] 4. Use denture base resin (commercially available product, the manufacturer in this application example is Shanghai New Century Dental Materials Co., Ltd.) to fill the visual cortex of the rat to seal the opened skull wound. After the wound around the twisted pair electrode 101 has been completely sealed with dental cement, continue to apply dental cement material until the exposed skull area and the outer area of ​​the electrode connection terminal 203 electrically connected to the end of the twisted pair electrode 101 of the present invention are completely covered. Then, connect the electrophysiological acquisition device to the electrode connection terminal 203 through the interface pin 301 to achieve the acquisition or electrical stimulation of signals in the visual perception area of ​​the rat cerebral cortex.

[0076] The signal diagram collected in this application example is as follows Figure 6 As shown, the sampling frequency is 500 Hz and the sampling time is 40 seconds.

Claims

1. A bidirectional double-twisted array EEG electrode, characterized by: The invention comprises a twisted pair electrode (1) and an electrode mounting seat (2), wherein the twisted pair electrode (1) comprises a PVA electrode rod (102) and a twisted pair electrode wire (101) formed by winding two single electrode wires, wherein the twisted pair electrode wire (101) is arranged in the PVA electrode rod (102) and the front end is exposed from the front end of the PVA electrode rod (102), a single electrode wire exposed at the front end of the twisted pair electrode wire (101) is provided with a contact site (1011) formed by removing an insulating layer, and the other single electrode wire is not provided with a contact site (1011), a circuit board (201) is provided in the electrode mounting seat (2), and a side of the circuit board (201) away from the front end of the twisted pair electrode (1) is provided with a plurality of electrode connection terminals (203), each PVA electrode rod (102) is arranged in the electrode mounting seat (2) in an array form, and the single electrode wires exposed at the rear end of the PVA electrode rod (102) are respectively electrically connected to the corresponding electrode connection terminals (203).

2. The bidirectional double-twisted array EEG electrode according to claim 1, characterized in that: The electrode mounting seat (2) is formed by coating the twisted electrode (1) array with biological glue (202) and then solidifying it.

3. The bidirectional double-twisted array EEG electrode according to claim 2, characterized in that: The biological glue is n-butyl cyanoacrylate adhesive.

4. The bidirectional double-twisted array EEG electrode according to claim 1, characterized in that: A front end section of the PVA electrode rod (102) extends from the electrode mounting seat (2) to form an implantation section, and an exposed twisted pair electrode wire (101) is provided at the front end of the implantation section.

5. The bidirectional double-twisted array EEG electrode according to claim 1, characterized in that: The side of the electrode mounting seat (2) away from the front end of the twisted pair electrode (1) is connected to the front end of an electrode extension seat (3); the rear end of the electrode extension seat (3) is provided with a plurality of interface pins (301), and each electrode connection terminal (203) is electrically connected to the corresponding interface pin (301).

6. The bidirectional double-twisted array EEG electrode according to claim 5, characterized in that: The electrode extension seat (3) is in the shape of a cone with a thin front and a thick rear, wherein the thin-diameter end of the electrode extension seat (3) is fixedly connected to the electrode mounting seat (2), and the thick-diameter end of the electrode extension seat (3) is provided with a plurality of interface pins (301) in an array form.

7. A method for preparing a bidirectional double-twisted array EEG electrode according to claim 1, characterized in that: The steps include: Step 1: twisting two single electrode wires to form a twisted pair of electrode wires (101); Step 2: etching away a predetermined number of insulating layers on the surface of one single electrode wire at the front end of the twisted pair of electrode wires (101) facing the other single electrode wire to form contact points (1011); Step 3: applying a photoresist layer of a set thickness on the surface of the resin base plate to form a base plate, and then etching the base plate to form grooves; Step 4: Filling the PVA solution into the groove; Step 5: soaking the twisted pair electrode wire (101) in the PVA solution in the groove, and baking to solidify the PVA to form a primary twisted pair electrode; Step 6: Combine the primary twisted pair electrodes into an array; Step 7: Soaking both ends of the primary twisted pair electrode array in water to remove the PVA material and form the final twisted pair electrode (1) array; Step 8: Untwist the twisted electrode wires (101) exposed at the ends of the twisted electrode (1) array, and use the single electrode wire with the contact site (1011) as the positive electrode and the other electrode wire as the negative electrode; Step nine: welding the positive electrode and the negative electrode to corresponding electrical points on the circuit board (201), and the electrical points are electrically connected to the electrode connection terminals (203) on the other side; Step 10: Using biological glue (202) to cover the twisted electrode (1) array and solidify it to form an electrode mounting seat (2).

8. A method for preparing a bidirectional double-twisted array EEG electrode according to claim 7, characterized in that: In step 2, the insulating layer is etched using femtosecond laser technology to form contact sites (1011), and in step 3, the bottom plate is etched using a photolithography machine to form grooves.

9. A method for preparing a bidirectional double-twisted array EEG electrode according to claim 7, characterized in that: In step six, the primary twisted pair electrodes are arranged in parallel in an array form, and the set positions of two adjacent primary twisted pair electrodes are bonded and fixed using biological glue (202), and the set length area with the contact site (1011) at the front end of the primary twisted pair electrode and the set length area at the end of the primary twisted pair electrode are not bonded.

10. A method for preparing a bidirectional double-twisted array EEG electrode according to claim 9, characterized in that: In step seven, the set length area of ​​the front end of the primary twisted pair electrode array that is not bonded is immersed in water for a set time to expose all contact points (1011), and the set length area of ​​the rear end of the primary twisted pair electrode array that is not bonded is immersed in water for a set time to expose the set length of the twisted pair electrode wire (101).

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