Integrated flexible corticobrain electrode and preparation method thereof

Abstract

The invention relates to an integrated flexible corticobrain electrode and a preparation method thereof.The flexible corticobrain electrode is composed of a flexible substrate layer, a wire layer and an insulating layer which are sequentially arranged in a stacked mode, the wire layer comprises an electrode contact array, a bonding pad contact array and a wire set, and the wire set spirally surrounds the electrode contact array; the bonding pad contact array is located on the outer side of the wire group; the electrode contact array and the flexible substrate layer and the insulating layer which correspond to each other up and down jointly form a signal acquisition electrode, the wire group and the flexible substrate layer and the insulating layer which correspond to each other up and down jointly form a connecting wire, and the bonding pad contact array and the flexible substrate layer and the insulating layer which correspond to each other up and down jointly form a bonding pad. The integrated flexible cortical brain electrode has the advantages of being small in size, high in flexibility and large in flux, in the using process, the signal collecting electrode can be better attached to a cerebral cortex collecting site, the problems of brain tissue damage and connection failure cannot occur, and the integrated flexible cortical brain electrode is friendly to experimental surgery operation.

Description

Technical Field

[0001] This invention belongs to the field of brain electrode technology, and in particular relates to an integrated flexible cortical brain electrode and its preparation method. Background Technology

[0002] Electroencephalography (EEG) monitoring has always played an irreplaceable role in the diagnosis and surgical localization of brain diseases. In recent years, with the launch of the global "Brain Initiative," effective and high-quality EEG signal acquisition has become increasingly important. This will directly contribute to brain function decoding and promote the development of a series of high-tech technologies based on this, such as brain-computer interfaces and neuromodulation. Methods for acquiring EEG signals mainly rely on brain electrodes. Currently, the most widely used brain electrodes include four types: 1) scalp EEG; 2) electrocorticography (ECoG); 3) cortical microelectrodes; and 4) deep EEG. Among them, the planar cortical electrode (ECoG), which lies between intracranial puncture microelectrodes and scalp external EEG, is placed on the surface of the subdural cortex. Due to its minimal invasiveness, it acquires surface electrical signals from the brain cortex with a higher noise-to-noise ratio, higher resolution (down to the submicron level), and a wider signal acquisition frequency range than scalp EEG, including information on the activity of cortical neuronal populations. It has broad application prospects in the diagnosis and monitoring of brain diseases and the improvement of the performance of brain-computer interface systems. Cortical electroencephalography (EEG) can be considered to have achieved an ideal balance between signal fidelity and clinical applicability, and therefore cortical EEG has been widely used in clinical practice.

[0003] Currently, flexible cortical EEG electrode systems are divided into four main parts, such as... Figure 1 As shown, the components are: a front-end flexible device 1, a flexible printed circuit board (FPC) 2, a lead wire 3, and a signal acquisition device 4. The front-end flexible device 1 is only designed to cover the area of ​​the cerebral cortex to be tested. The flexible printed circuit board 2, serving as the back-end signal connection, is designed to be 20-50 cm in length to meet the requirements of the experimental surgery. The flexible printed circuit board 2 itself is only used as a connection between the device and the lead wire 3. It employs industrial printed circuit board manufacturing processes, with a batch processing precision limit of approximately 2 mils (0.508 mm). The large-area board is difficult to process, thus significantly limiting the design of various types of circuit boards. In the final EEG signal acquisition system, the flexible printed circuit board 2 is thermo-pressed to the flexible electrode device using an anisotropic conductive film (ACF) to complete the conductive assembly. Due to the separate assembly design of the front-end flexible device 1 and the FPC, as well as limitations in the processing of the FPC itself, the currently widely used separate EEG electrodes still have many shortcomings. Since the thickness of the FPC itself can reach hundreds of micrometers, compared to the front-end device (thickness less than twenty micrometers), its thickness and stiffness are too great, and its flexibility and adhesion are far inferior. Furthermore, the connection point between the two is close to brain tissue, and the presence of FPC may lead to the following problems:

[0004] 1) The flexible front-end device cannot adhere well to the cerebral cortex acquisition site, such as... Figure 2 As shown;

[0005] 2) Due to its rigidity, it carries the risk of damaging brain tissue;

[0006] 3) There is a risk that the connection between the two may fail due to prolonged contact with bodily fluids.

[0007] 4) Due to the limitations of its processing technology, FPCs have a huge circuit board area for a certain number of channels. The design of multi-layer circuit boards will increase their thickness many times over, making it difficult to achieve both small size and flexibility, and also difficult to meet the needs of high-throughput devices.

[0008] 5) The large-area electrode rear end connection plate increased the difficulty of operation during experimental surgery. Summary of the Invention

[0009] The main objective of this invention is to propose an integrated flexible cortical brain electrode and its preparation method, which can effectively solve the problems in the background art.

[0010] To achieve the above objectives, the present invention employs the following technical solutions for testing:

[0011] An integrated flexible cortical brain electrode is characterized by comprising a flexible substrate layer, a conductive layer, and an insulating layer stacked sequentially. The conductive layer includes an electrode contact array, a pad contact array, and a conductive group. The conductive group includes a plurality of conductive lines. Each electrode contact in the electrode contact array is connected to a corresponding pad contact in the pad contact array via a conductive line. The conductive group is spirally wound around the electrode contact array, and the pad contact array is located outside the conductive group.

[0012] The electrode contact array, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a signal acquisition electrode; the wire group, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a connecting line; and the pad contact array, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a pad.

[0013] The insulating layer has a first hole at the position of each electrode contact on the electrode contact array, through which the electrode contact is exposed so that it can contact the scalp layer to collect EEG signals. The insulating layer also has a second hole at the position of each pad contact on the pad contact array, through which the pad contact is exposed so that it can be connected to a signal acquisition device.

[0014] Preferably, there is a preset distance between adjacent connecting lines, which is greater than 0 and less than or equal to 1 centimeter.

[0015] Preferably, the polar coordinate path of the connecting line satisfies r = a + bθ;

[0016] Where r represents the distance of a point on the connecting line from the center point, θ is the angle between a point on the connecting line and the standard line, and a and b represent characteristic parameters related to the width of the spiral.

[0017] Preferably, the electrode contact array includes a 64-channel electrode array, a 256-channel electrode array, or a 529-channel electrode array.

[0018] Preferably, the flexible substrate layer and the insulating layer are made of flexible polymer materials.

[0019] A method for fabricating an integrated flexible cortical brain electrode includes the following steps:

[0020] S1: Provide a silicon substrate;

[0021] S2: A sacrificial layer is prepared on the silicon substrate;

[0022] S3: Fabricate a flexible substrate layer on the sacrificial layer;

[0023] S4: Fabricate a conductive layer on a flexible substrate. The conductive layer includes an electrode contact array, a pad contact array, and a conductive group. The conductive group includes several conductive lines. Each electrode contact in the electrode contact array is connected to a corresponding pad contact in the pad contact array via a conductive line. The conductive group is spirally wrapped around the electrode contact array. The pad contact array is located outside the conductive group.

[0024] S5: An insulating layer is prepared on the conductor layer, so that the electrode contact array, the pad contact array and the conductor group are wrapped between the flexible substrate layer and the insulating layer;

[0025] S6: Based on the overall outline of the electrode contact array, the pad contact array, and the lead wire group, the insulating layer and the flexible substrate layer are patterned and the excess parts are etched away. The electrode contact array together with the corresponding upper and lower flexible substrate layers and insulating layers form the signal acquisition electrode. The lead wire group together with the corresponding upper and lower flexible substrate layers and insulating layers form the connecting line. The pad contact array together with the corresponding upper and lower flexible substrate layers and insulating layers form the pad.

[0026] Simultaneously, a first hole is etched on the insulating layer at the position of each electrode contact on the electrode contact array to expose the electrode contact so that the electrode contact can contact the scalp layer and collect EEG signals. A second hole is etched on the insulating layer at the position of each pad contact on the pad contact array to expose the pad contact so that the pad contact can be connected to the signal acquisition device.

[0027] S7: Release the sacrificial layer and the silicon substrate region corresponding to the sacrificial layer to prepare the integrated flexible cortical brain electrode.

[0028] Preferably, in step S2, when the sacrificial layer is prepared, the sacrificial layer is first sputtered, then patterned, and then etched away in the area corresponding to the pad contact array.

[0029] Preferably, in step S4, the method for preparing the conductive layer is to deposit a metal material layer on a flexible substrate, pattern the metal material layer, and etch it to form an electrode contact array, a pad contact array, and a conductive array.

[0030] Preferably, in step S7, after the integrated flexible cortical brain electrode is prepared, the connecting wire is wound around the mandrel and twisted and coiled to form a hollow thin wire. Then, the connecting wire is shaped using bio-silicone to obtain the integrated flexible cortical brain electrode after twisting and fixing.

[0031] This invention provides an integrated flexible cortical brain electrode and its preparation method, which has the following beneficial effects:

[0032] 1. The integrated flexible cortical brain electrode of the present invention is composed of a flexible substrate layer, a wire layer and an insulating layer stacked sequentially. It can be fabricated on a standard 4-inch or 6-inch silicon wafer using MEMS processing technology, so that the signal acquisition electrode, connecting wire and bonding pad are integrated. Compared with the traditional split brain electrode assembled with a flexible front-end device and a flexible circuit board, the integrated flexible cortical brain electrode of the present invention has the advantages of small size, high flexibility and high throughput. During use, the signal acquisition electrode can better attach to the acquisition site of the cerebral cortex, without the problem of damage to brain tissue and connection failure, and is friendly to experimental surgical operations.

[0033] 2. The lead wire group of the present invention is spirally wrapped around the electrode contact array, and the pad contact array is located outside the lead wire group. That is, the connecting line is spirally wrapped around the signal acquisition electrode, and the pad is located outside the connecting line. The spiral structure design of the connecting line can achieve the effect of small and concentrated overall processing area of ​​the device with a certain length of connecting line, and process the connecting line that meets the experimental operation length on a limited silicon substrate area. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a flexible cortical brain electrode system in the prior art;

[0035] Figure 2 This is a schematic diagram illustrating the connection between the front-end flexible device and the flexible circuit board in the prior art.

[0036] Figure 3This is a schematic diagram of an optional integrated flexible cortical brain electrode according to the present invention;

[0037] Figure 4 This is a schematic diagram of another optional integrated flexible cortical brain electrode of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the signal acquisition electrode of the present invention;

[0039] Figure 6 This is a flowchart illustrating the fabrication process of the integrated flexible cortical brain electrode of the present invention.

[0040] Figure 7 This is a schematic diagram of the integrated flexible cortical brain electrode after the connecting wires of the present invention have been twisted and fixed.

[0041] Figure 8 This is an application scenario diagram of the integrated flexible cortical brain electrode of Embodiment 3 of the present invention;

[0042] Figure 9 This is an application scenario diagram of the integrated flexible cortical brain electrode of Embodiment 4 of the present invention.

[0043] In the diagram: 1. Front-end flexible device; 2. Flexible circuit board; 3. Lead wire; 4. Signal acquisition device; 5. Conductor layer; 51. Electrode contact array; 52. Conductor group; 53. Pad contact array; 6. Flexible substrate layer; 7. Insulating layer; 71. First hole; 72. Second hole; 73. Through hole; 8. Connecting line; 9. Signal acquisition electrode; 10. Pad; 11. Silicon substrate; 12. Sacrificial layer; 13. Support substrate. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0045] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0048] Example 1

[0049] Reference Figure 3 , Figure 6 This invention provides an integrated flexible cortical brain electrode, which is composed of a flexible substrate layer 6, a wire layer 5 and an insulating layer 7 stacked sequentially. The wire layer 5 includes an electrode contact array 51, a pad contact array 53 and a wire group 52. The wire group 52 includes a plurality of wires. Each electrode contact in the electrode contact array 51 is connected to a corresponding pad contact on the pad contact array 53 by a wire. The wire group 52 is spirally wrapped around the electrode contact array 51, and the pad contact array 53 is located outside the wire group 52.

[0050] The electrode contact array 51, together with the corresponding upper and lower flexible substrate layer 6 and insulating layer 7, forms the signal acquisition electrode 9; the wire group 52, together with the corresponding upper and lower flexible substrate layer 6 and insulating layer 7, forms the connecting line 8; and the pad contact array 53, together with the corresponding upper and lower flexible substrate layer 6 and insulating layer 7, forms the pad 10.

[0051] The insulating layer 7 has a first hole 71 at the position of each electrode contact on the electrode contact array 51, through which the electrode contact is exposed so that the electrode contact can contact the scalp layer to collect EEG signals. The insulating layer 7 also has a second hole 72 at the position of each pad contact on the pad contact array 53, through which the pad contact is exposed so that the pad contact can be connected to the signal acquisition device.

[0052] The integrated flexible cortical brain electrode of the present invention consists of a flexible substrate layer 6, a wire layer 5, and an insulating layer 7 stacked sequentially. It can be fabricated on a standard 4-inch or 6-inch silicon wafer using MEMS processing technology, so that the signal acquisition electrode 9, the connecting line 8, and the pad 10 are integrated. Compared with the traditional separate brain electrode assembled with the front-end flexible device 1 and the flexible circuit board 2, the integrated flexible cortical brain electrode of the present invention has the advantages of small size, high flexibility, and high throughput. During use, the signal acquisition electrode 9 can better adhere to the acquisition site of the cerebral cortex, without the problems of damage to brain tissue and connection failure, and is friendly to experimental surgical operations.

[0053] The lead wire group 52 of the present invention is spirally wrapped around the electrode contact array 51, and the pad contact array 53 is located outside the lead wire group 52. That is, the connecting line 8 is spirally wrapped around the signal acquisition electrode 9, and the pad 10 is located outside the connecting line 8. The spiral structure design of the connecting line 8 can achieve the effect of small and concentrated overall processing area of ​​the device with a certain length of connecting line, and process the connecting line 8 that meets the experimental operation length on a limited silicon substrate area.

[0054] It should be noted that the present invention is not limited to the connection line 8 being spirally wrapped around the signal acquisition electrode 9, with the pad 10 located outside the connection line 8, as shown in the reference. Figure 4 Alternatively, the connecting line 8 can be spirally wrapped around the pad 10, with the signal acquisition electrode 9 located outside the connecting line 8. Both structural layouts can be designed according to the number of channels and the width of the connecting line, as long as the overall structure occupies a small area.

[0055] As a further specific embodiment, in the spiral structure, there is a preset distance between adjacent connecting lines 8, which is greater than 0 and less than or equal to 1 centimeter. Preferably, the preset distance is greater than 50 micrometers and less than 500 micrometers.

[0056] As a further specific implementation, in order to make the overall structure of the brain electrode structure occupy a smaller size on the substrate, the polar coordinate path of the connecting line 8 satisfies r=a+bθ.

[0057] Where r represents the distance of a point on the connecting line from the center point, θ is the angle between a point on the connecting line and the standard line, and a and b represent characteristic parameters related to the width of the connecting line.

[0058] As a further specific implementation, the electrode contact array 51 includes a 64-channel electrode array, a 256-channel electrode array, or a 529-channel electrode array.

[0059] As a further specific embodiment, the flexible substrate layer 6 and the insulating layer 7 are made of flexible polymer materials, such as polyimide or SU8.

[0060] As a further specific implementation method, refer to Figure 5 Through holes 73 are provided between adjacent first holes 71 or second holes 72 on the flexible substrate layer 6 and the insulating layer 7. The flexibility of the signal acquisition electrode 9 and the pad 10 can be further improved by setting several through holes 73.

[0061] Example 2

[0062] This invention also provides a method for preparing an integrated flexible cortical brain electrode, comprising the following steps:

[0063] S1: Provides a silicon substrate 11, see reference. Figure 6 Figure (a) in the middle;

[0064] S2: A sacrificial layer 12 is fabricated on the silicon substrate 11, see [reference] Figure 6 Figure (b) in the middle;

[0065] Preferably, the sacrificial layer 12 is made of aluminum and has a thickness of 0.5-2 micrometers.

[0066] S3: A flexible substrate layer 6 is fabricated on the sacrificial layer 12, see [reference]. Figure 6 Figure (d) in the middle;

[0067] Preferably, the flexible substrate layer 6 is made of biocompatible polyimide.

[0068] S4: See also Figure 3 as well as Figure 6 Figures (e) and (f) show that a conductive layer 5 is fabricated on a flexible substrate layer 6. The conductive layer 5 includes an electrode contact array 51, a pad contact array 53, and a conductive group 52. The conductive group 52 includes a plurality of conductive lines. Each electrode contact in the electrode contact array 51 is connected to a corresponding pad contact on the pad contact array 53 via a conductive line. The conductive group 52 is spirally wrapped around the electrode contact array 51, and the pad contact array 53 is located outside the conductive group 52.

[0069] Specifically, the method for fabricating the conductive layer 5 is to deposit a metal material layer on the flexible substrate layer 6, pattern the metal material layer, and etch it to form an electrode contact array 51, a pad contact array 53, and a conductive group 52.

[0070] Preferably, the electrode contacts and wires are made of any one of chromium / gold, chromium / silver, or chromium / platinum.

[0071] Preferably, the material of the solder pad contacts is any one of chromium / nickel / gold, chromium / nickel / silver, or chromium / nickel / platinum.

[0072] S5: See Figure 6 In Figure (g), an insulating layer 7 is prepared on the conductor layer 5, so that the electrode contact array 51, the pad contact array 53 and the conductor group 52 are wrapped between the flexible substrate layer 6 and the insulating layer 7.

[0073] S6: See also Figure 3 as well as Figure 6 In Figure (h), the insulating layer 7 and the flexible substrate layer 6 are patterned according to the overall outline of the electrode contact array 51, the pad contact array 53 and the wire group 52, and the excess parts are etched away. The electrode contact array 51 and the corresponding upper and lower flexible substrate layer 6 and insulating layer 7 together form the signal acquisition electrode 9. The wire group 52 and the corresponding upper and lower flexible substrate layer 6 and insulating layer 7 together form the connecting line 8. The pad contact array 53 and the corresponding upper and lower flexible substrate layer 6 and insulating layer 7 together form the pad 10.

[0074] Simultaneously, a first hole 71 is etched on the insulating layer 7 at the position of each electrode contact on the electrode contact array 51, exposing the electrode contact through the first hole 71 so that the electrode contact can contact the scalp layer to collect EEG signals. A second hole 72 is etched on the insulating layer 7 at the position of each pad contact on the pad contact array 53, exposing the pad contact through the second hole 72 so that the pad contact can be connected to the signal acquisition device.

[0075] S7: See also Figure 6 In Figure (i), the sacrificial layer 12 and the silicon substrate 11 region corresponding to the sacrificial layer 12 are released to prepare the integrated flexible cortical brain electrode.

[0076] As a further specific implementation, in step S2, when the sacrificial layer 12 is prepared, refer to... Figure 6 In Figures (b) and (c), the sacrificial layer 12 is sputtered first, then the sacrificial layer 12 is patterned, and the area corresponding to the pad contact array 53 is etched away. This increases the thickness of the pads. In step S7, when the sacrificial layer 12 and the area of ​​the silicon substrate 11 corresponding to the sacrificial layer 12 are released, a portion of the silicon substrate 11 can be retained to form a support substrate 13, thereby improving the strength of the connection between the pads and external devices.

[0077] As a further specific implementation, in step S7, after the integrated flexible cortical brain electrode is prepared, the connecting wire 8 cannot be stretched into a straight state by its planar structural layout alone. In order to facilitate use, the connecting wire 8 needs to be wound around the mandrel and twisted and coiled to form a hollow thin wire. Then, the connecting wire 8 is shaped using bio-silicone.

[0078] Specifically, during the shaping of the connecting wire, bio-silicone type A and type B are thoroughly mixed in a 1:1 ratio. The mixture is then applied to the twisted and coiled connecting wire, completely encapsulating it. The integrated flexible cortical brain electrode is then placed in an oven and baked at 50°C for 2 hours to fully solidify and shape it. Finally, the core rod is removed. (See reference...) Figure 6 This process yields an integrated flexible cortical brain electrode after twisting and fixing. Bio-silicone is a flexible material and does not affect the flexibility of the connecting wires themselves after curing and shaping; the twisted and coiled wires can be bent arbitrarily. Furthermore, because bio-silicone also possesses a certain degree of elasticity, the twisted and coiled wires also have a certain degree of stretchability, with a length elongation range of 0–5 cm.

[0079] In this embodiment, the diameter of the thin thread can be controlled according to the diameter of the wound mandrel (the thinnest diameter is approximately 1 mm), while the length of the thin thread can be controlled according to the density of the winding of the connecting thread. For example, a connecting thread with a planar design length of 45 cm can be twisted and curled to form a thin thread with a length ranging from 20 to 35 cm.

[0080] Considering the aseptic requirements of the experimental surgical procedure, and in order to reduce the risk of infection during the surgery, the suture should meet a certain length requirement, usually 10 to 30 centimeters.

[0081] Addressing the issue of bulky and redundant back-end connections in current split-type electrodes, this invention integrates the front-end signal acquisition section of a flexible brain electrode with a back-end FPC connection board, designing an integrated flexible cortical brain electrode and its fabrication method. The flexible cortical brain electrode features slender connecting wires and utilizes a helical structure to improve manufacturability. Employing MEMS fabrication technology, the flexible cortical brain electrode maintains a lightweight and slender back-end connection even with high throughput. The connecting wires can be twisted and assembled according to application requirements, and their shape is fixed using bio-silicone to form thin wires. The assembled length and thickness are adjustable, and after shaping, they retain a certain degree of tensile strength, enhancing operational convenience, significantly reducing potential biological risks, and providing the possibility for minimally invasive long-term acquisition of EEG signals. The integrated flexible cortical brain electrode fabricated by this invention can be applied in neuroscience research for the detection of large-scale EEG signals and in signal acquisition related to cutting-edge technologies and artificial intelligence.

[0082] The following describes in more detail the use of the integrated flexible cortical brain electrode of the present invention in different application scenarios, with reference to specific embodiments.

[0083] Example 3

[0084] The integrated flexible cortical brain electrode prepared by this invention can be used for acute electroencephalogram (EEG) signal acquisition, such as... Figure 7 As shown, Figure 7 This is a diagram illustrating an optional brain electrode structure application scenario provided by this application. The brain electrode structure is placed on the cerebral cortex, and the twisted and fixed thin wire can be buried under the skin until it hangs behind the ear or down to the clavicle. The pads are connected to the lead wire 3, which is connected to the signal acquisition device 4.

[0085] Example 4

[0086] The integrated flexible cortical brain electrode prepared by this invention can be implanted in vivo for a long period of time to collect signals from the corresponding region. (See also...) Figure 8 , Figure 8 This is an illustration of another optional brain electrode structure application scenario provided by this application. The brain electrode structure is placed on the brain region to be sampled. The thin wire, after being twisted, coiled and fixed, is buried under the skull and then connected to the pad 10 through the skull. The pad 10 can be fixed in the base of the skull. It is small in size and light in weight. The pad 10 is connected to the lead wire 3, which is connected to the signal acquisition device 4.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An integrated flexible cortical brain electrode, characterized in that: It consists of a flexible substrate layer, a conductive layer and an insulating layer stacked sequentially. The conductive layer includes an electrode contact array, a pad contact array and a conductive group. The conductive group includes a plurality of conductive lines. Each electrode contact in the electrode contact array is connected to a corresponding pad contact in the pad contact array via a conductive line. The conductive group is spirally wrapped around the electrode contact array. The pad contact array is located outside the conductive group. The electrode contact array, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a signal acquisition electrode; the wire group, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a connecting line; and the pad contact array, together with the corresponding upper and lower flexible substrate layers and insulating layers, forms a pad. The insulating layer has a first hole at the position of each electrode contact on the electrode contact array, through which the electrode contact is exposed so that it can contact the scalp layer to collect EEG signals. The insulating layer also has a second hole at the position of each pad contact on the pad contact array, through which the pad contact is exposed so that it can be connected to a signal acquisition device.

2. The integrated flexible cortical brain electrode according to claim 1, characterized in that: There is a preset distance between adjacent connecting lines, which is greater than 0 and less than or equal to 1 centimeter.

3. The integrated flexible cortical brain electrode and its preparation method according to claim 1, characterized in that: The polar coordinate path of the connecting line satisfies r = a + bθ; Where r represents the distance of a point on the connecting line from the center point, θ is the angle between a point on the connecting line and the standard line, and a and b represent characteristic parameters related to the width of the spiral.

4. The integrated flexible cortical brain electrode according to claim 1, characterized in that: Electrode contact arrays include 64-channel, 256-channel, or 529-channel electrode arrays.

5. The integrated flexible cortical brain electrode according to claim 1, characterized in that: The flexible substrate layer and the insulating layer are made of flexible polymer materials.

6. A method for preparing an integrated flexible cortical brain electrode, characterized in that, Includes the following steps: S1: Provide a silicon substrate; S2: A sacrificial layer is prepared on the silicon substrate; S3: Fabricate a flexible substrate layer on the sacrificial layer; S4: Fabricate a conductive layer on a flexible substrate. The conductive layer includes an electrode contact array, a pad contact array, and a conductive group. The conductive group includes several conductive lines. Each electrode contact in the electrode contact array is connected to a corresponding pad contact in the pad contact array via a conductive line. The conductive group is spirally wrapped around the electrode contact array. The pad contact array is located outside the conductive group. S5: An insulating layer is prepared on the conductor layer, so that the electrode contact array, the pad contact array and the conductor group are wrapped between the flexible substrate layer and the insulating layer; S6: Based on the overall outline of the electrode contact array, the pad contact array, and the lead wire group, the insulating layer and the flexible substrate layer are patterned and the excess parts are etched away. The electrode contact array together with the corresponding upper and lower flexible substrate layers and insulating layers form the signal acquisition electrode. The lead wire group together with the corresponding upper and lower flexible substrate layers and insulating layers form the connecting line. The pad contact array together with the corresponding upper and lower flexible substrate layers and insulating layers form the pad. Simultaneously, a first hole is etched on the insulating layer at the position of each electrode contact on the electrode contact array to expose the electrode contact so that the electrode contact can contact the scalp layer and collect EEG signals. A second hole is etched on the insulating layer at the position of each pad contact on the pad contact array to expose the pad contact so that the pad contact can be connected to the signal acquisition device. S7: Release the sacrificial layer and the silicon substrate region corresponding to the sacrificial layer to prepare the integrated flexible cortical brain electrode.

7. The method for preparing an integrated flexible cortical brain electrode according to claim 6, characterized in that: In step S2, during the preparation of the sacrificial layer, the sacrificial layer is first sputtered, then patterned, and then etched away in the area corresponding to the pad contact array.

8. The method for preparing an integrated flexible cortical brain electrode according to claim 6, characterized in that: In step S4, the method for fabricating the conductive layer is to deposit a metal material layer on a flexible substrate, pattern the metal material layer, and etch it to form an electrode contact array, a pad contact array, and a conductive array.

9. The method for preparing an integrated flexible cortical brain electrode according to claim 6, characterized in that: In step S7, after the integrated flexible cortical brain electrode is prepared, the connecting wire is wound around the mandrel and twisted to form a hollow thin wire. Then, the connecting wire is shaped using bio-silicone to obtain the integrated flexible cortical brain electrode after twisting and fixing.

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