A brain electrode device and a preparation method thereof

Abstract

The present invention provides a brain electrode device, comprising a circuit board, a first tape layer, a flexible electrode structure, a second tape layer and a chip; the flexible electrode structure includes a connected implantation structure and a backend structure; the backend structure includes a pad accommodation hole and a plurality of circuit board exposure through holes, the materials of the first tape layer and the second tape layer are polyimide, the electrode solder accommodation hole of the second tape layer is aligned with the pad accommodation hole of the flexible electrode structure to form a first polymer through hole, and the first polymer through hole is filled with solder to form an electrode pad; a part of the pins of the chip are welded to the electrode pad, and another part of the pins of the chip pass through the circuit board exposure through holes and are welded and fixed to the circuit board pads. The brain electrode device and its preparation method of the present invention achieve small size, light weight and high integration of the brain electrode device on the premise of firm welding and fixing.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the priority of the Chinese utility model patent application with the application number 202323482344.4 filed on December 19, 2023, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of brain electrodes, and particularly relates to a brain electrode device and a preparation method thereof. Background Art

[0004] Brain-computer interface technology is a technology that directly connects the human brain to a computer or other external devices, which can record and interpret brain signals, thereby realizing interaction with external devices. In this field, flexible electrodes, as a key component, are widely used in the recording and stimulation of neural tissues.

[0005] Currently, the commonly used brain electrode device usually transfers the front-end flexible electrode to a circuit with a signal processing chip through a silicon-based adapter, such as an intan device. However, there are three important problems with the current connection device for transferring the flexible electrode used in experiments to a circuit with a chip: First, the pre-stage probe of the intan device is relatively large in size, and an additional PCB with a chip needs to be transferred, resulting in complex connections and inconvenient interface connections; Second, due to the transfer between the flexible electrode and the signal processing chip, the signal quality is unstable; Finally, the above-mentioned brain electrode device is also relatively large and heavy in size, and the weight of the two PCBs at the position of the mouse's head is significantly greater than the weight of the mouse's head, which generates greater pressure on the mouse's head, thus affecting the movement of the acquisition object (such as a mouse) and further affecting the signal acquisition result. Summary of the Invention

[0006] The purpose of the present invention is to provide a brain electrode device and a preparation method thereof to achieve small size, light weight, and high integration of the brain electrode device on the premise of firm welding and fixation.

[0007] To achieve the objective, the present invention provides a brain electrode device, which includes a circuit board, a first tape layer, a flexible electrode structure, a second tape layer and a chip stacked in sequence from bottom to top; the flexible electrode structure includes a connected implant structure and a backend structure; a plurality of recording electrodes are provided on the implant structure for collecting brain nerve signals; the backend structure includes a pad accommodating hole and a plurality of circuit board exposure through-holes, and the circuit board exposure through-holes are used to expose the circuit board pads on the circuit board; the materials of the first tape layer and the second tape layer are polyimide, and an electrode solder accommodating hole is provided on the second tape layer. The electrode solder accommodating hole on the second tape layer is aligned with the pad accommodating hole of the flexible electrode structure to form a first polymer through-hole, and solder is filled in the first polymer through-hole to form the electrode pads of the flexible electrode structure; the circuit board is connected to an external acquisition device; a part of the pins of the chip are welded to the electrode pads, and another part of the pins of the chip pass through the circuit board exposure through-holes and are welded and fixed to the circuit board pads.

[0008] Circuit board solder accommodating holes are provided on the first tape layer and the second tape layer; the circuit board solder accommodating holes on the first tape layer and the second tape layer are aligned with the circuit board exposure through-holes and the circuit board pads on the circuit board to form a second polymer through-hole, and solder is filled in the second polymer through-hole to form the solder layer of the circuit board; the other part of the pins of the chip are welded to the circuit board pads through the solder layer.

[0009] The flexible electrode structure further includes a transfer structure; one end of the transfer structure is connected to the implant structure, and the other end of the transfer structure is connected to the backend structure; a plurality of the recording electrodes are respectively connected to corresponding electrode pads through a wire.

[0010] The flexible electrode structure includes a plurality of the implant structures; the plurality of implant structures are arranged at intervals along the width direction of the transfer structure.

[0011] The circuit board exposure through-holes include a first through-hole and a second through-hole; the size of the first through-hole is smaller than the size of the second through-hole; the second through-hole is located in the middle of the backend structure; the first through-holes are distributed around the second through-hole.

[0012] The flexible electrode structure includes a flexible substrate, a wiring layer and an insulating layer arranged in sequence from bottom to top; the materials of the flexible substrate and the insulating layer include polyimide or SU-8.

[0013] The welding method of the pins of the chip to the electrode pads and the circuit board pads includes reflow soldering.

[0014] On the other hand, the present invention provides a preparation method of the brain electrode device according to the above, including:

[0015] S1: Preparation of flexible electrode structure;

[0016] S2: aligning the first tape layer with a circuit board pad of a circuit board and pasting it on the circuit board;

[0017] S3: aligning the flexible electrode structure with the circuit board pad and pasting it on the first tape layer;

[0018] S4: Align the second tape layer with the circuit board pad and stick it on the flexible electrode structure, then align the electrode solder receiving holes of the second tape layer filled with solder with the pad receiving holes of the flexible electrode structure to form a first polymer through hole, and align the circuit board solder receiving holes of the first tape layer and the second tape layer with the circuit board pad on the circuit board to form a second polymer through hole.

[0019] The step S1 specifically includes:

[0020] S11: providing a clean substrate;

[0021] S12: preparing a sacrificial layer, a flexible substrate, a wiring layer and an isolation layer in sequence on the surface of the substrate, wherein the materials of the flexible substrate and the insulation layer include polyimide or SU-8;

[0022] S13: using aluminum as a mask, forming an outline pattern of a flexible electrode structure on the aluminum mask by photolithography technology, and subsequently etching the flexible substrate and the isolation layer by reactive ion etching process to obtain a flexible electrode structure;

[0023] S14: releasing the substrate to obtain a flexible electrode structure.

[0024] In step S3, a glass slide is fixed at the front end of the transfer device, a piece of PDMS is glued under the glass slide, the bottom surface of the flexible electrode structure is attached to the surface of the PDMS with the bottom surface facing upward, the flexible electrode structure is vertically aligned with the circuit board pad through microscopic observation, and then the bottom surface of the flexible electrode structure is attached to the first tape layer with the bottom surface facing downward.

[0025] The brain electrode device of the present invention uses polyimide, a high-performance polymer, as a base material to make a flexible electrode structure, and then the flexible electrode structure is connected to the circuit board and the chip through a polyimide tape with a solder receiving hole, wherein the polyimide adhesive is aligned with the flexible electrode structure to form a polymer through-hole. Then, using the PCB as the device substrate, the flexible electrode structure and the chip are welded together by hot-melting solder in the solder receiving hole, thereby achieving direct and firm welding and fixing between the pad of the flexible electrode structure and the pin of the chip. As a result, the flexible electrode structure and the chip do not need to be provided with an additional adapter chip and can be directly welded together, thereby minimizing additional interfaces, simplifying the collection of neural signals, and achieving a small size, light weight, and high integration of the brain electrode device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 is a structural schematic diagram of a flexible electrode structure provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of the structure of an implant structure provided in an embodiment of the present application;

[0029] Figure 3 is a schematic structural diagram of a brain electrode device provided in an embodiment of the present application;

[0030] Figure 4 It is a structural schematic diagram of a process for preparing a flexible electrode structure provided in an embodiment of the present application;

[0031] Figure 5 It is a structural schematic diagram of another flexible electrode structure provided in an embodiment of the present application.

[0032] Figure 6 This is a size comparison diagram of the brain electrode device of the present application and the existing brain electrode device, wherein the left side is the size of the existing brain electrode device, the middle is the size of the brain electrode device of the present application, and the right side is the size of a one-yuan coin.

[0033] Reference numerals:

[0034] 1-flexible electrode structure; 11-implantation structure; 111-recording electrode; 12-rear end structure; 121-pad accommodating hole; 122-circuit board exposed through hole; 123-first through hole; 124-second through hole; 13-transfer structure; 2-circuit board; 3-chip; 5-electrode pad; 4-substrate. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] As used herein, "one embodiment" or "an embodiment" refers to a particular feature, structure, or characteristic that may be included in at least one implementation of the present application. In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Moreover, the terms "first", "second", etc. are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data may be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0037] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as every value therebetween. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. For example, a specified range from "1 to 10" should be considered to include any and all sub-ranges between the minimum value 1 and the maximum value 10. Exemplary sub-ranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0038] The brain electrode device of the present invention is inspired by the silicon through-hole technology in advanced three-dimensional packaging, and a method for polyimide polymer through-hole is designed. Specifically, the brain electrode device of the present invention is mainly based on the following principles: a flexible electrode structure 1 is made of a high-performance polymer, polyimide, as a base material, and then the flexible electrode structure 1 is connected to the circuit board 2 and the chip 3 (i.e., a commercial brain-computer interface chip) through a polyimide tape with a solder receiving hole, wherein the polyimide adhesive is aligned with the flexible electrode structure 1 to form a polymer through-hole. Subsequently, the PCB is used as the device substrate, and the flexible electrode structure 1 and the chip 3 are welded together by hot-melting solder in the solder receiving hole, thereby achieving direct and firm welding and fixing between the pad of the flexible electrode structure 1 and the pin of the chip 3. As a result, the flexible electrode structure 1 and the chip 3 do not need to be provided with an additional adapter chip and are directly welded together, which minimizes additional interfaces, simplifies the collection of neural signals, and achieves a small size, light weight, and high integration of the brain electrode device.

[0039] Figures 1 - 3 A brain electrode device according to an embodiment of the present application comprises a circuit board 2, a first tape layer, a flexible electrode structure 1, a second tape layer and a chip 3 stacked in sequence from bottom to top. The first tape layer and the second tape layer play a fixing role.

[0040] The base material of the flexible electrode structure 1 is polyimide or SU-8 negative photoresist, which does not have a silicon-containing base material; the material of the first tape layer and the second tape layer is polyimide. In this embodiment, the thickness of the flexible electrode structure 1 is 2 microns, and the thickness of the first tape layer and the second tape layer is 300 microns. It is difficult to directly weld the pins and pads of the chip 3, so a certain thickness of the first tape layer and the second tape layer is required to assist the welding of the two.

[0041] like Figure 1 and Figure 2 The flexible electrode structure 1 comprises an implant structure 11 and a rear end structure 12 connected by a transfer structure 13. The rear end structure 12 is provided with a plurality of pad receiving holes 121 and a plurality of circuit board exposed through holes 122, and the shapes of the first tape layer and the second tape layer are the same as those of the rear end structure 12. The chip 3 is located directly above the rear end structure 12.

[0042] Among them, a plurality of circuit board pads are provided on the circuit board 2, and a plurality of circuit board exposed vias 122 are used to expose the circuit board pads on the circuit board 2. A part of the pins of the chip 3 (i.e., signal processing pins) pass through the circuit board exposed vias 122 of the flexible electrode structure 1 and are welded and fixed to the circuit board pads on the circuit board 2. Thus, at the position where the circuit board exposed vias 122 are located, the pins of the chip 3 are welded and fixed to the circuit board pads on the circuit board 2, and the circuit board exposed vias 122 of the flexible electrode structure 1 are sleeved on the pins of the chip 3 but are not welded to the chip 3 and the circuit board 2.

[0043] Among them, electrode solder accommodating holes are provided on the second tape layer, and the electrode solder accommodating holes of the second tape layer are aligned with the pad accommodating holes 121 of the flexible electrode structure 1 to form a first polymer via hole. Solder is filled in the first polymer via hole (including the holes at the second tape layer and the flexible electrode structure) to form the electrode pads 5 of the flexible electrode structure 1. The electrode pads 5 are used to weld a part of the pins of the chip 3 (i.e., signal acquisition pins). Since the polymer via hole only contains the electrode solder accommodating holes of the second tape layer, the bottom end face of the formed solder layer is insulated and closed and does not contact the circuit board 2. One of the end faces is welded and fixed to the circuit board 2. Thus, the electrode pads 5 formed by melting the solder at the first polymer via hole connect the flexible electrode structure 1 and the pins of the chip 3 more firmly, and the flexible electrode structure 1 and the circuit board 2 are fixed together through the first tape layer.

[0044] Circuit board solder accommodating holes are provided on the first tape layer and the second tape layer. The circuit board solder accommodating holes of the first tape layer and the second tape layer are aligned with the circuit board exposed vias 122 and the circuit board pads on the circuit board 2 to form a second polymer via hole. Solder is filled in the second polymer via hole to form the solder layer of the circuit board 2. Another part of the pins of the chip 3 are welded to the circuit board pads through the solder layer.

[0045] In this embodiment, the welding method of the pins of the chip 3 to the electrode pads 5 and the circuit board pads includes reflow soldering.

[0046] It should be noted that the electrode pads 5 do not contact the circuit board 2, and the two can be separated by the first tape layer under the flexible electrode structure 1 or by the bottom flexible substrate of the multi-layer flexible electrode structure 1.

[0047] In this embodiment, the number of the electrode pads 5 is 16, and the electrode pads 5 are used to weld 16 pins of the chip 3.

[0048] Therefore, the brain electrode device of the present invention achieves welding and fixing of the circuit board 2, the flexible electrode structure 1 and a part of the pins of the chip 3 by using the electrode pad 5, and the other part of the pins of the chip 3 are welded and fixed to the circuit board pads of the circuit board 2 through the multiple circuit board exposed through holes 122 on the rear end structure 12, so that the overall device has better integration and smaller size under the premise of achieving stable welding and fixing, which is conducive to reducing the brain pressure of the experimental subject, improving the accuracy of the motion detection of the experimental subject, and improving the quality of the collected signal. In addition, the design of the polymer through hole also helps to use the coating of solder and then reflow soldering to weld the flexible electrode structure 1 and the chip 3, and the chip 3 and the circuit board 2 together in the specific molding process, making the entire molding process simpler and less costly.

[0049] The implant structure 11 is provided with a plurality of recording electrodes 111 for collecting brain nerve signals, wherein each recording electrode 111 is connected to a pad receiving hole 121 through a wire, thereby being electrically connected to the electrode pad 5 corresponding to the pad receiving hole 121 .

[0050] See also Figure 2 , the wire is simultaneously arranged in the implant structure 11, the rear-end structure 12 and the adapter structure 13. The plurality of recording electrodes 111 are distributed on the same side of the wire. Optionally, the plurality of recording electrodes 111 may be distributed on different sides of the plurality of wires. Since the electrode pad 5 is connected to the chip 3, the EEG signals collected by the recording electrode 111 can be transmitted to the chip 3 in sequence through the wire and the electrode pad 5, and then processed by the chip 3 and transmitted to the external acquisition device through the circuit board 2. The chip 3 is used to process the EEG signals collected by the plurality of recording electrodes 111 to obtain processed signals, and transmit the processed signals to the external acquisition device through the circuit board 2.

[0051] The flexible electrode structure 1 further includes a transfer structure 13; one end of the transfer structure 13 is connected to the implant structure 11, and the other end of the transfer structure 13 is connected to the rear end structure 12. In this embodiment, at least a portion of the pads are disposed on a side of the rear end structure 12 close to the transfer structure 13, so that the electrode pads 5 are close to the recording electrode 111, shortening the signal transmission path and improving the signal processing efficiency and quality.

[0052] In this embodiment, the circuit board exposed through hole 122 includes a first through hole 123 and a second through hole 124; the size of the first through hole 123 is smaller than the size of the second through hole 124; the second through hole 124 is located in the middle of the rear end structure 12; the first through hole 123 is located around the second through hole 124. Both the first through hole 123 and the second through hole 124 are used to provide a channel for soldering and conducting the chip 3 with the circuit board 2.

[0053] Specifically, the plurality of electrode pads 5 can be distributed only on one side of the second through hole 124. When the number of electrode pads 5 is large and the overall size of the rear-end structure 12 is small, the plurality of electrode pads 5 can also be distributed on two adjacent sides of the second through hole 124, or on three adjacent sides, without limitation. Optionally, the size of the transfer structure 13 can be specifically designed to match the size of the rear-end structure 12.

[0054] In this embodiment, the flexible electrode structure 1 includes a plurality of the implant structures 11; the plurality of implant structures 11 are arranged at intervals along the width direction of the adapter structure 13. Optionally, the implant structure 11 can pass through multiple brain regions of rodents and reach the hippocampus, striatum, prefrontal lobe or hypothalamus. Optionally, the length of the implant structure 11 ranges from 3 to 10 mm; optionally, it can be 3 mm, 5 mm, 8 mm or 10 mm. Optionally, the number and spacing of the recording electrodes 111 and the length of the implant structure 11 can be designed according to the brain region to be implanted, the size and shape of the rear-end structure 12 can be designed according to the size and pad of the chip 3, and the circuit board 2 is designed based on minimizing the volume and weight, and facilitating surgical implantation operations and subsequent signal acquisition.

[0055] The flexible electrode structure 1 may include a multilayer structure. Specifically, the flexible electrode structure 1 may include a flexible substrate, a wiring layer, and an insulating layer arranged in sequence from bottom to top; optionally, the materials of the flexible substrate and the insulating layer may include polyimide or SU-8. The flexible electrode structure 1 is obtained by micro-nano processing methods such as baking polyimide film, metal evaporation, photolithography, and RIE etching.

[0056] In this embodiment, the implant structure 11, the transfer structure 13 and the rear-end structure 12 can be integrally formed. The wiring layer includes a plurality of recording electrodes 111 and a plurality of wires connected one by one. Two types of through holes are provided on the insulating layer. The first type of through holes is located on the implant structure 11 and is used to expose the plurality of recording electrodes 111; the second type of through holes is located on the rear-end structure 12, corresponding to the pad accommodating holes 121 and the circuit board exposed through holes 122. A hole is opened on the flexible substrate at a position corresponding to the circuit board exposed through hole 122, but is closed (i.e., there is no opening) at a position corresponding to the pad accommodating hole 121, thereby making the circuit board exposed through hole 122 a through hole, and the pad accommodating hole 121 a hole with one end closed. Optionally, multiple wiring layers can be provided as needed, and an insulating layer is provided between each wiring layer.

[0057] The circuit board 2 is connected to an external acquisition device via an FPC connection line.

[0058] Based on the above-mentioned brain electrode device, the method for preparing the brain electrode device includes:

[0059] Step S1: Prepare the flexible electrode structure 1;

[0060] The specific structure of the flexible electrode structure 1 is as described above.

[0061] The specific steps of step S1 include:

[0062] Step S11: Provide a clean substrate 4;

[0063] Among them, the substrate 4 can be a silicon oxide wafer, and step S11 includes: cleaning the substrate 4 to remove surface moisture and contaminants;

[0064] Step S12: Sequentially prepare a sacrificial layer, a flexible substrate, a wiring layer, and an isolation layer on the surface of the substrate 4. The materials of the flexible substrate and the insulating layer include polyimide or SU-8;

[0065] In this embodiment, a 50 - 120 nm thick AL is deposited on its surface by metal evaporation as the sacrificial layer, a 1 - 3 um thick polyimide film is spin-coated, and then put into an oven and cured into a film through a set temperature-rising program to form a flexible substrate; then the wiring layer is fabricated by photolithography and metal evaporation processes. Next, a polyimide film is formed on the wiring layer as the isolation layer;

[0066] Step S13: Use aluminum as a mask, and form a contour pattern of the flexible electrode structure 1 on the aluminum mask through photolithography technology. Subsequently, a reactive ion etching (RIE) process is used to etch the flexible substrate and the isolation layer to obtain the flexible electrode structure 1 (for the contour pattern, please refer to Figure 4 );

[0067] Step S14: Release the substrate 4 to obtain the flexible electrode structure 1 as shown in Figure 5 ;

[0068] Step S2: Align the first tape layer with the circuit board pad and paste it on the circuit board 2;

[0069] In step S2, a double-sided polyimide tape cut by laser is used as the first tape layer. Under a stereomicroscope, the first tape layer is picked up with tweezers, aligned with the circuit board pad and pasted on the circuit board 2, pressed to make it stick firmly, and then the surface protective film of the first tape layer is torn off;

[0070] Among them, the alignment of the first tape layer with the circuit board pad is achieved by aligning the circuit board solder receiving holes with the circuit board pads on the circuit board 2 to form the second polymer through-holes.

[0071] Step S3: Align the flexible electrode structure 1 with the circuit board pad and paste it on the first tape layer;

[0072] In step S3, a glass slide is fixed at the front end of the transfer device, a piece of PDMS is adhered under the glass slide, the bottom surface of the flexible electrode structure 1 is placed face up on the surface of the PDMS, the flexible electrode structure 1 is vertically aligned with the circuit board pad through microscopic observation, and then the bottom surface of the flexible electrode structure 1 is slowly placed face down on the first tape layer.

[0073] Step S4: Align the second tape layer with the circuit board pad and paste it on the flexible electrode structure 1. Subsequently, solder is filled in the first polymer through hole formed by aligning the electrode solder accommodating hole of the second tape layer with the pad accommodating hole 121 of the flexible electrode structure 1, and the circuit board solder accommodating holes of the first tape layer and the second tape layer are aligned with the circuit board pads on the circuit board 2 to form the second polymer through hole.

[0074] In step S4, a piece of polyimide tape is used as the second tape layer, and the second tape layer is picked up with tweezers and pasted on the flexible electrode structure 1. Then, a little low-temperature solder paste is taken with a disposable surgical blade as the solder and applied in the first polymer through hole and the second polymer through hole. After scraping the surface clean with the blade, the surface protective film of the second tape layer is torn off with tweezers.

[0075] Step S5: Align the chip 3 with the circuit board pad and paste it on the surface of the second tape layer.

[0076] Among them, a chip of model RHS2116 is picked up with tweezers and aligned with the position of the circuit board pad. Pay attention to observing the positions of the pins of the chip and the solder, and gently press it to make it adhere to the surface of the second tape layer.

[0077] Step S6: Heat the assembled circuit board 2, the first tape layer, the flexible electrode structure 1, the second tape layer and the chip 3 to obtain the brain electrode device.

[0078] Among them, a hot air gun is used to heat from the top of the chip 3.

[0079] Thus, 1) The present invention uses polyimide tape to provide basic stability for the ultra-thin and flexible flexible electrodes, otherwise the flexible electrodes tend to curl. By fixing with polyimide tape, the necessary rigidity during the bonding process is ensured. And with the customized transfer platform, the tape ensures the precise alignment of the chip and the flexible electrode, ensuring the prevention of displacement during the subsequent assembly stage.

[0080] 2) The customized polyimide tape has laser-cut apertures (i.e., electrode solder accommodating holes and circuit board solder accommodating holes), which serve as reservoirs for the solder paste and significantly facilitate the bonding process.

[0081] 3) The polyimide tape acts as a protective buffer, reducing the risk of scratch damage between the PCB, flexible electrodes, and chips during the assembly process.

[0082] Figure 6 is a size comparison diagram of the brain electrode device of the present application and the existing brain electrode device. On the left is the size of the existing brain electrode device, in the middle is the size of the brain electrode device of the present application, and on the right is the size of a one-yuan coin. From Figure 6 it can be seen that the brain electrode device of the present application is smaller in size, stronger in weight, and achieves high integration.

[0083] Based on the brain electrode device provided by the present application, through the design of the flexible electrode structure 1, the flexible electrode structure 1 is integrated with the circuit board 2 and the chip 3, realizing the lightweight of the system, avoiding the influence of the large-volume brain electrode device on the movement of mice, being able to improve the quality of the collected signals, and reducing the complexity of the connection of the backend interface, further improving the signal quality.

[0084] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A brain electrode device, characterized in that: It comprises a circuit board (2), a first adhesive tape layer, a flexible electrode structure (1), a second adhesive tape layer and a chip (3) which are stacked in sequence from bottom to top; The flexible electrode structure (1) comprises a connected implant structure (11) and a rear end structure (12); The implant structure (11) is provided with a plurality of recording electrodes (111) for collecting brain nerve signals; The rear end structure (12) comprises a pad accommodating hole (121) and a plurality of circuit board exposing through holes (122), wherein the circuit board exposing through holes (122) are used to expose circuit board pads on the circuit board (2); The first tape layer and the second tape layer are made of polyimide, the second tape layer is provided with an electrode solder accommodating hole, the electrode solder accommodating hole of the second tape layer is aligned with the pad accommodating hole (121) of the flexible electrode structure (1) to form a first polymer through hole, and the first polymer through hole is filled with solder to form an electrode pad (5) of the flexible electrode structure; The circuit board (2) is connected to an external data collection device; A portion of the pins of the chip (3) are welded to the electrode pad (5), and another portion of the pins of the chip (3) pass through the exposed through holes (122) of the circuit board and are welded and fixed to the circuit board pad.

2. The brain electrode device according to claim 1, characterized in that The first tape layer and the second tape layer are provided with circuit board solder receiving holes; The circuit board solder receiving holes of the first tape layer and the second tape layer are aligned with the circuit board exposed through hole (122) and the circuit board pad on the circuit board to form a second polymer through hole, and the second polymer through hole is filled with solder to form a solder layer of the circuit board; Another part of the pins of the chip (3) are welded to the welding pads of the circuit board through the welding layer.

3. The brain electrode device according to claim 1, characterized in that The flexible electrode structure (1) further comprises a switching structure (13); One end of the adapter structure (13) is connected to the implant structure (11), and the other end of the adapter structure (13) is connected to the rear end structure (12); The plurality of recording electrodes (111) are respectively connected to a corresponding electrode pad (5) via a wire.

4. The brain electrode device according to claim 3, characterized in that The flexible electrode structure (1) comprises a plurality of implant structures (11); The plurality of implant structures (11) are arranged at intervals along the width direction of the transfer structure (13).

5. The brain electrode device according to claim 1, characterized in that The circuit board exposed through hole (122) comprises a first through hole (123) and a second through hole (124); the size of the first through hole (123) is smaller than the size of the second through hole (124); The second through hole (124) is located in the middle of the rear end structure (12); The first through holes (123) are distributed around the second through holes (124).

6. The brain electrode device according to claim 1, characterized in that The flexible electrode structure (1) comprises a flexible substrate, a wiring layer and an insulating layer arranged in sequence from bottom to top; The materials of the flexible substrate and the insulating layer include polyimide or SU-8.

7. The brain electrode device according to claim 1, characterized in that The welding method of the pins of the chip (3) and the electrode pads (5) and the circuit board pads includes reflow soldering.

8. A method for preparing a brain electrode device according to any one of claims 1 to 7, characterized in that: include: Step S1: preparing a flexible electrode structure (1); Step S2: aligning the first adhesive tape layer with a circuit board pad of a circuit board (2), and adhering the first adhesive tape layer to the circuit board (2); Step S3: aligning the flexible electrode structure (1) with the circuit board pad and pasting it on the first tape layer; Step S4: align the second tape layer with the circuit board pad and adhere it to the flexible electrode structure (1), then align the electrode solder receiving hole of the second tape layer filled with solder with the pad receiving hole (121) of the flexible electrode structure (1) to form a first polymer through hole, and align the circuit board solder receiving hole of the first tape layer and the second tape layer with the circuit board pad on the circuit board (2) to form a second polymer through hole.

9. The method for preparing the brain electrode device according to claim 8, characterized in that: The step S1 specifically includes: Step S11: providing a clean substrate (4); Step S12: preparing a sacrificial layer, a flexible substrate, a wiring layer and an isolation layer in sequence on the surface of the substrate (4), wherein the materials of the flexible substrate and the insulation layer include polyimide or SU-8; Step S13: using aluminum as a mask, forming an outline pattern of the flexible electrode structure (1) on the aluminum mask by photolithography, and subsequently etching the flexible substrate and the isolation layer by reactive ion etching to obtain the flexible electrode structure (1); Step S14: releasing the substrate (4) to obtain a flexible electrode structure (1).

10. The method for preparing the brain electrode device according to claim 8, characterized in that: In step S3, a glass slide is fixed at the front end of the transfer device, a piece of PDMS is glued under the glass slide, the bottom surface of the flexible electrode structure (1) is attached to the surface of the PDMS with the bottom surface facing upwards, the flexible electrode structure (1) is vertically aligned with the circuit board pad through microscopic observation, and then the bottom surface of the flexible electrode structure (1) is attached to the first tape layer with the bottom surface facing downwards.

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