Flexible neural electrode and management method

Abstract

The invention discloses a flexible neural electrode and a management method, and belongs to the technical field of flexible neural electrodes. The problems that an existing flexible electrode is difficult to strip and low in preparation efficiency are solved. The flexible neural electrode comprises a plurality of electrode bodies, tearing stripping structures, fixing structures and a silicon substrate, the plurality of electrode bodies are arranged in parallel, the two sides of each electrode body are respectively connected with one tearing stripping structure, and the fixing structures are connected between the tearing stripping structures connected with the adjacent electrode bodies. All the electrode bodies, the tearing and stripping structures and the fixing structures form an electrode integral film; the electrode integral thin film is connected with the silicon substrate through the sacrificial layer; an electrode anchor point is arranged at the tail end of each electrode body in the electrode integral thin film, and the electrode anchor points are connected with the silicon substrate. According to the invention, efficient management and controllable release of the electrode are realized.

Description

Technical Field

[0001] The invention relates to a flexible neural electrode and a management method thereof, and belongs to the technical field of flexible neural electrodes. Background Art

[0002] Flexible neural electrodes are a type of neural interface device with micron-sized dimensions. Their typical structural features are: thickness in the micron range, width in the tens to hundreds of microns range, and length in the tens of millimeters to tens of centimeters range. This miniaturized design gives the electrode extremely low mechanical stiffness, making it particularly suitable for invasive implantation in the nervous system. However, this structural feature also brings significant challenges to the operation of the electrode.

[0003] During the preparation process, flexible electrodes are usually manufactured on silicon wafers using micro-electromechanical systems (MEMS) technology. However, the release and operation management of electrodes become key technical difficulties due to the following two main reasons:

[0004] 1) The electrodes cannot be directly operated on the silicon substrate and need to be released;

[0005] 2) The slender structure of the electrode shows strong uncontrollability during the wet release process.

[0006] To address the above challenges, researchers developed an electrode management strategy based on the "fixation-separation" principle. This strategy can be divided into two key stages:

[0007] A. Preparation phase, including:

[0008] Fix the flexible electrode on a larger management medium; achieve precise positioning and position control of the electrode through the management medium; ensure that the electrode remains in an operable state;

[0009] B. Implantation phase, including:

[0010] Achieve controllable separation of the electrode and the management medium; restore the electrode to a free state; and complete the positioning and implantation of the electrode in the target brain tissue.

[0011] Currently, two typical electrode management methods based on this strategy have been widely studied:

[0012] 1) Parylene-C film-assisted method: a Parylene-C polymer film tens of microns thick is deposited during the electrode preparation process. Its advantage is that it ensures that the electrodes are regularly arranged after release, which is convenient for operation; its disadvantage is that the interface bonding force is large, and the peeling process may cause damage to the electrodes or microneedles.

[0013] 2) Pre-assembly method: The released electrode floats on the water surface and the surface tension is used to flatten the electrode. Then the flattened electrode is bonded to the implanted microneedle by polyethylene glycol (PEG) to form a pre-assembly. After implantation, PEG dissolves in the physiological environment to achieve natural separation of the electrode and the microneedle. The advantage is that it avoids the mechanical stripping process and reduces the risk of electrode damage; the disadvantage is that the operation process is complicated and the preparation efficiency is low.

[0014] The development of these management methods has greatly promoted the practical application of flexible neural electrodes, but further optimization is still needed to improve operational efficiency and reliability. Summary of the invention

[0015] In view of the problems of difficulty in stripping and low preparation efficiency of existing flexible electrodes, the present invention provides a flexible neural electrode and a management method.

[0016] A flexible neural electrode of the present invention comprises a plurality of electrode bodies, a tearing and peeling structure, a fixing structure and a silicon substrate.

[0017] Multiple electrode bodies are arranged in parallel, and a tearing and peeling structure is connected to both sides of each electrode body, and a fixing structure is connected between the tearing and peeling structures connected to adjacent electrode bodies, and all electrode bodies, tearing and peeling structures and fixing structures form an electrode integral film; the electrode integral film is connected to the silicon substrate through a sacrificial layer;

[0018] The end of each electrode body in the electrode integral film is an electrode anchor point, and the electrode anchor point is connected to the silicon substrate.

[0019] According to the flexible neural electrode of the present invention, the electrode anchor point is generated by a patterned sacrificial layer method.

[0020] According to the flexible neural electrode of the present invention, the tearing and peeling structure is a structure formed by a plurality of regularly arranged broken lines or arrow lines.

[0021] According to the flexible neural electrode of the present invention, a plurality of regularly arranged fold lines or arrow lines of the tearing and peeling structure are arranged at equal intervals along the length direction of the electrode body on the silicon substrate.

[0022] According to the flexible neural electrode of the present invention, the fixing structure includes a plurality of release grids, each of which is a square frame.

[0023] The present invention also provides a method for managing a flexible neural electrode, which is used to manage the flexible neural electrode, comprising:

[0024] The sacrificial layer between the electrode overall film and the silicon substrate is removed by using an etchant, and the electrode overall film and the silicon substrate are separated when the electrode anchor point is connected to the silicon substrate; after separation, the electrode overall film is attached to the silicon substrate;

[0025] Post-processing the entire electrode film after separation, and making the entire electrode film after separation automatically flattened on the silicon substrate;

[0026] The electrode integral film after automatic flattening is aligned with the easily separable new substrate, and the electrode integral film after automatic flattening is adsorbed from the silicon substrate to the easily separable new substrate through adhesion force.

[0027] According to the management method of the flexible neural electrode of the present invention, the post-processing includes cleaning, bonding and surface modification.

[0028] According to the management method of the flexible neural electrode of the present invention, the method for realizing automatic flattening of the entire electrode film after separation is: making the entire electrode film after separation pass through the gas-liquid interface multiple times starting from the anchor point position, and under the action of the interface force, realizing automatic flattening of the entire electrode film on the silicon substrate.

[0029] According to the flexible neural electrode management method of the present invention, the easily detachable new substrate absorbs the automatically flattened electrode overall film by heating or pressurizing.

[0030] According to the management method of the flexible neural electrode of the present invention, the easily detachable new substrate is a polydimethylsiloxane substrate or a polymethyl methacrylate substrate.

[0031] Beneficial effects of the present invention: The present invention designs an invasive flexible neural electrode and a transfer process in use, which can reduce the surface energy between the electrode and the substrate. It achieves efficient management and controllable release of the electrode by creating a new electrode-substrate interface and an electrode structure that matches the transfer process. The substrate transfer mechanism achieves moderate adhesion between the electrode and the transition substrate with a specific surface energy through interface engineering, thereby achieving adhesion regulation. The optimized electrode structure keeps the electrode in a complete film state during the transfer and processing stages before peeling. By introducing a stress concentration area, the stress distribution during the peeling process can be controlled by structural regulation.

[0032] It has been verified by experiments that the method of the present invention can effectively reduce the interfacial adhesion. Compared with the traditional Parylene-C method, the interfacial adhesion is reduced by more than 50%. The mechanical damage to the electrode during the peeling process is greatly reduced. The technical requirements for implantation tools and equipment are reduced. The process compatibility of the present invention is good. A wet release process is adopted, and the structure is used to ensure reliable passage through the liquid interface. It is compatible with common post-processing processes of flexible neural electrodes, such as surface modification and wire bonding. The flexible neural electrode described in the present invention is suitable for efficient batch preparation. Compared with the pre-assembly method, the process steps are simple and the operation repeatability is good. It has the potential for automated production.

[0033] The method of the present invention provides reliable technical support for the large-scale preparation and clinical application of flexible neural electrodes, and has important practical value and industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the structure of the flexible neural electrode of the present invention;

[0035] Figure 2 It is a schematic diagram of the design principle of the fixed structure; the arrow in the figure indicates the etching direction;

[0036] Figure 3 It is a schematic diagram of the design principle of the tearing and peeling structure;

[0037] Figure 4 It is an electron microscope image of the tearing and peeling structure;

[0038] Figure 5 It is a schematic diagram of the principle of flattening the entire electrode film by using the electrode anchor point;

[0039] Figure 6 It is a schematic diagram of the process of transferring the entire electrode film from the silicon substrate to the new substrate. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0042] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0043] Specific implementation method 1. Combination Figures 1 to 4 As shown, the present invention provides a flexible neural electrode, comprising a plurality of electrode bodies 100, a tearing and peeling structure 200, a fixing structure 300 and a silicon substrate 400.

[0044] Multiple electrode bodies are arranged in parallel, and a tearing and peeling structure is connected to both sides of each electrode body, and a fixing structure is connected between the tearing and peeling structures connected to adjacent electrode bodies, and all electrode bodies, tearing and peeling structures and fixing structures form an electrode integral film; the electrode integral film is connected to the silicon substrate through a sacrificial layer;

[0045] The end of each electrode body in the electrode integral film is an electrode anchor point, and the electrode anchor point is connected to the silicon substrate.

[0046] In this embodiment, the electrode body 100 is the functional part that is actually implanted in the brain tissue. The fixed structure 300 is a filling structure connected to the electrode body 100, and together with the electrode body 100, it forms a large-area thin film. During the release process, the overall stability of the electrode is maintained, and temporary mechanical support is provided to prevent the electrode from being deformed or damaged during the transfer process. The anchor point serves as the connection area with the substrate after the electrode is released, and when the electrode film passes through the air-liquid interface, it balances the surface tension and can flatten the electrode. The tearing and peeling structure serves as a prefabricated vulnerable area connecting the fixed structure and the electrode body. Before tearing, the entire electrode is in a complete thin film state. After tearing, the body is separated from the fixed structure.

[0047] The design of the electrode structure in this embodiment can ensure that the electrodes exist in the form of sheets rather than wires during the release process, and the electrodes are maintained in an orderly arrangement under the action of structural constraints.

[0048] The tearing and peeling structure combines geometric design and MEMS manufacturing technology to form a strength controllable area. Its typical design is as follows Figure 3 As shown in the figure, the arrow-shaped windows and retained materials are arranged alternately to form a regular array, and stress concentration is generated along the symmetry line. During the MEMS processing, due to the lateral etching effect, the material strength around the window area will be reduced, thus forming a predetermined tearing weak area. By adjusting the geometric structure design and process parameters, the location and strength of the tearing can be precisely controlled. The actual tearing peeling structure is shown in Figure 4 As shown in the electron microscope image.

[0049] As an example, the electrode anchor point is generated by patterning a sacrificial layer, and the sacrificial layer is removed at the anchor point design position, so that the portion of the film is directly formed on the silicon substrate.

[0050] Combination Figure 3 As shown, as an example, the tearing and peeling structure is a structure formed by a plurality of regularly arranged fold lines; the plurality of fold lines are arranged at equal intervals along the length direction of the electrode body on the silicon substrate.

[0051] As an example, the tearing and peeling structure is a structure formed by a plurality of regularly arranged arrow lines; the plurality of arrow lines are arranged at equal intervals along the length direction of the electrode body on the silicon substrate.

[0052] Combination Figure 2 As shown, as an example, the fixing structure includes a plurality of release grids, each of which is a square frame. The release grid allows etching from multiple directions at the same time during release, such as Figure 2As shown, on the one hand, the etching speed is accelerated to avoid over-etching and damage to the electrode contacts; on the other hand, the etching uniformity can be improved to avoid uneven force on the film to cause wrinkles.

[0053] Specific implementation method 2: Combination Figures 1 to 6 As shown, the present invention also provides a method for managing a flexible neural electrode, which is used to manage the flexible neural electrode described in the first embodiment, comprising:

[0054] The sacrificial layer between the electrode overall film and the silicon substrate is removed by using an etchant, and the electrode overall film and the silicon substrate are separated when the electrode anchor point is connected to the silicon substrate; after separation, the electrode overall film is attached to the silicon substrate;

[0055] Post-processing the entire electrode film after separation, and making the entire electrode film after separation automatically flattened on the silicon substrate;

[0056] The machine vision system is used to assist in alignment and position the electrode and the new substrate. The electrode film after automatic flattening is aligned with the new substrate that is easy to separate, and the electrode management is completed by adsorbing the electrode film from the silicon substrate to the new substrate that is easy to separate through adhesion.

[0057] When the managed flexible neural electrode is used for implantation, the implanted microneedle is connected to the pull ring of the electrode body, and the electrode body is driven by the movement of the implanted microneedle, so that the electrode body is broken from the tearing and peeling structure and separated from the easily detachable new substrate, thereby obtaining a separated electrode body.

[0058] The electrode body, as the functional part actually implanted into the brain tissue, usually includes a head pull ring and a recording site, which is connected to the fixed structure through a tearing and peeling structure.

[0059] In this embodiment, a release grid is designed on the fixed structure so that etching can be performed from multiple directions simultaneously during release, such as Figure 2 As shown, on the one hand, the etching speed is accelerated to avoid over-etching and damage to the electrode contacts; on the other hand, the etching uniformity can be improved to avoid uneven force on the film to cause wrinkles.

[0060] As an example, according to the application requirements of the electrode, the post-treatment includes cleaning, bonding and surface modification.

[0061] Furthermore, the method for achieving automatic flattening of the entire electrode film after separation is: allowing the entire electrode film after separation to pass through the gas-liquid interface multiple times starting from the anchor point position, and under the action of the interface force, achieving automatic flattening of the entire electrode film on the silicon substrate.

[0062] As an example, the easily detachable new substrate establishes a moderate adhesion force between the electrode and the new substrate by means of precisely controlled heating or pressurization, and adsorbs the entire electrode film that is automatically flattened.

[0063] As an example, the easily separable new substrate is a polydimethylsiloxane substrate or a polymethyl methacrylate substrate.

[0064] Polydimethylsiloxane (PDMS) substrate is used. Since both the electrode and the PDMS substrate have nano-level flat surfaces, the two are adsorbed by van der Waals force. Apply appropriate pressure to ensure that the two are in full contact.

[0065] A polymethyl methacrylate (PMMA) substrate is used, and appropriate pressure and heating are applied to deform the PMMA substrate, thereby improving the degree of adhesion with the electrode film. At the same time, the electrode film is adsorbed under the action of electrostatic force.

[0066] The electrode transfer of this embodiment includes four key steps:

[0067] 1) Release: The sacrificial layer between the electrode's entire film and the silicon substrate is selectively removed by a specific etchant to separate the electrode from the silicon wafer. The existence of the fixed structure and the tearing structure allows the electrode to maintain a complete film state and maintain the relative position between the electrodes. The anchor structure allows the electrode to maintain a local connection with the silicon wafer, and in subsequent steps, the electrode can be indirectly operated by operating the silicon wafer.

[0068] 2) Post-processing steps: According to the application requirements of the electrode, including cleaning, bonding and surface modification processes. In this process, the electrode needs to pass through the gas-liquid interface many times, such as Figure 5 As shown, the electrode is passed through the interface starting from the anchor point structure position. Under the action of the interface force, the film can be automatically flattened to avoid curling and winding.

[0069] 3) Alignment and adsorption: Use a machine vision system to assist in alignment and position the electrode and the new substrate, such as Figure 6 As shown, through precisely controlled pressure, heating and other means, moderate adhesion is established between the electrode and the new substrate, ensuring sufficient adsorption without affecting the subsequent peeling process.

[0070] The peeling mechanism of this embodiment has the following characteristics:

[0071] Controllable process: the peeling path is predefined by the tear peeling structure;

[0072] Stress optimization: low peeling force, reducing the strength requirements of the operator and microneedle;

[0073] High reliability: easy to operate and not prone to damage electrodes, suitable for clinical application scenarios.

[0074] In summary, the present invention achieves efficient management and controllable release of flexible neural electrodes through an innovative combination of structural design and process flow, providing reliable technical support for its clinical application.

[0075] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A flexible neural electrode, characterized in that: It includes a plurality of electrode bodies, a tearing and peeling structure, a fixing structure and a silicon substrate. Multiple electrode bodies are arranged in parallel, each electrode body is connected to a tearing and peeling structure on both sides, and the tearing and peeling structures connected to adjacent electrode bodies are connected to a fixed structure, and all electrode bodies, tearing and peeling structures and fixed structures form an electrode integral film; the electrode integral film is connected to the silicon substrate through a sacrificial layer; The end of each electrode body in the electrode integral film is an electrode anchor point, and the electrode anchor point is connected to the silicon substrate.

2. The flexible neural electrode according to claim 1, characterized in that: The electrode anchor point is generated by patterning a sacrificial layer.

3. The flexible neural electrode according to claim 1, characterized in that: The tearing and peeling structure is a structure formed by a plurality of regularly arranged fold lines or arrow lines.

4. The flexible neural electrode according to claim 1, characterized in that: A plurality of regularly arranged fold lines or arrow lines of the tearing and peeling structure are arranged at equal intervals along the length direction of the electrode body on the silicon substrate.

5. The flexible neural electrode according to claim 1, characterized in that: The fixing structure includes a plurality of release grids, each of which is a square frame.

6. A method for managing a flexible neural electrode, used for managing the flexible neural electrode according to claim 1, characterized in that: include: The sacrificial layer between the electrode overall film and the silicon substrate is removed by using an etchant, and the electrode overall film and the silicon substrate are separated when the electrode anchor point is connected to the silicon substrate; after the separation, the electrode overall film is attached to the silicon substrate; Post-processing the entire film of the separated electrode and making the entire film of the separated electrode automatically flattened on the silicon substrate; The electrode integral film after automatic flattening is aligned with the easily separable new substrate, and the electrode integral film after automatic flattening is adsorbed from the silicon substrate to the easily separable new substrate through adhesion force.

7. The method for managing a flexible neural electrode according to claim 6, characterized in that: The post-processing includes cleaning, bonding and surface modification.

8. The method for managing a flexible neural electrode according to claim 6, characterized in that: The method for achieving automatic flattening of the entire electrode film after separation is: making the entire electrode film after separation pass through the gas-liquid interface multiple times starting from the anchor point position, and under the action of the interface force, the entire electrode film is automatically flattened on the silicon substrate.

9. The method for managing a flexible neural electrode according to claim 6, characterized in that: The easily separable new substrate absorbs the automatically flattened electrode integral film by heating or pressurizing.

10. The method for managing a flexible neural electrode according to claim 6, characterized in that: The new easily separable substrate is a polydimethylsiloxane substrate or a polymethyl methacrylate substrate.

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