Flexible electrode for brain-computer interface and preparation method thereof

Abstract

The invention provides a flexible electrode for a brain-computer interface and a preparation method of the flexible electrode. The flexible electrode comprises an electrode body layer, an auxiliary transmission layer and a stripping layer. Wherein the electrode body layer and the auxiliary transfer layer are at least partially connected to form a stress part of an external driving part, and the stripping layer is arranged between the electrode body layer and the auxiliary transfer layer, so that preset areas of the electrode body layer and the auxiliary transfer layer are separated to form a gap. According to the flexible electrode, the area of a bone window needing to be cut in the skull in the implanting process of the electrode can be remarkably reduced, and therefore the clinical operation risk of electrode implanting is greatly reduced.

Description

Technical Field

[0001] This application relates to the field of brain-computer interface technology, and in particular to a flexible electrode for brain-computer interfaces and a method for preparing the same. Background Technology

[0002] Brain-computer interfaces (BCIs) have revolutionized the diagnosis and treatment of many neurological diseases by establishing an information highway between the brain and external devices. Multichannel electrode arrays are the core hardware of BCIs. By acquiring neural signals in real time, they provide objective evidence for disease classification, pathological mechanism research, and the identification of therapeutic targets, enabling the localization of epileptic foci, characterizing abnormal rhythms in Parkinson's disease, and assessing functional remodeling after stroke. Furthermore, by applying closed-loop interventions based on real-time neural signals through this electrode array, precise treatments such as seizure prediction and suppression, and adaptive regulation of Parkinson's symptoms can be achieved, driving the diagnosis and treatment of neurological diseases towards personalization and dynamism.

[0003] Multichannel electrode arrays can be categorized into non-invasive, semi-invasive, and fully invasive types based on the degree of trauma inflicted during deployment. Non-invasive electrodes are placed outside the scalp, resulting in severe attenuation and blurring of neural signals as they pass through the skull and scalp, low spatial resolution, and susceptibility to noise interference from muscle activity. Fully invasive electrodes penetrate directly into the cerebral cortex or deep brain tissue, achieving extremely high spatiotemporal resolution neural signals, but the implantation surgery is highly invasive, posing risks of brain tissue damage, hemorrhage, infection, and long-term immune rejection. To balance surgical trauma and signal quality, semi-invasive arrays based on flexible cortical electrodes have gained widespread attention. These flexible cortical electrodes are implanted within the skull but outside the cerebral cortex. Compared to fully invasive methods, they do not directly penetrate brain tissue, resulting in relatively lower risks of infection and inflammation, and higher safety. Furthermore, compared to non-invasive methods, the signal is not affected by skull interference, leading to a significantly higher signal-to-noise ratio and spatial resolution.

[0004] While semi-invasive flexible electrodes significantly reduce brain tissue damage during implantation and long-term use, they do not significantly reduce skull trauma. For example, the clinical application of high-density, ultra-thin flexible cortical electrodes still requires opening a bone window several centimeters in diameter in the skull, cutting the dura mater, and placing the electrode array directly on the exposed cortical surface, causing considerable trauma. Furthermore, large-scale craniotomy carries a high risk of infection, cerebrospinal fluid leakage, severe postoperative pain, a long recovery period, and significant exposure and disturbance of brain tissue, potentially leading to inflammatory reactions and glial scar formation, thus affecting signal quality and long-term stability. In addition, the repair of large bone windows is also quite complex.

[0005] Therefore, it is necessary to develop a novel flexible electrode structure for brain-computer interfaces to reduce the area of ​​bone windows that need to be cut in the skull during implantation. Summary of the Invention

[0006] In view of this, this application provides a flexible electrode for brain-computer interface and a method for preparing the same, which aims to reduce the area of ​​the bone window that needs to be cut in the skull during implantation.

[0007] The first aspect of this application provides a flexible electrode for a brain-computer interface. The flexible electrode includes an electrode body layer, an auxiliary transmission layer, and a release layer. The electrode body layer and the auxiliary transmission layer are at least partially connected to form a force-bearing part of an external driving member. The release layer is disposed between the electrode body layer and the auxiliary transmission layer to separate a predetermined area of ​​the electrode body layer and the auxiliary transmission layer, forming a gap.

[0008] In some embodiments, the electrode body layer includes a flexible support layer, the flexible support layer includes a first adhesive portion and a contact area, the first adhesive portion is disposed close to the contact area, and the auxiliary transmission layer includes a second adhesive portion, the second adhesive portion being connected to the first adhesive portion, so that the electrode body layer and the auxiliary transmission layer form the force-bearing portion at the connection.

[0009] In some embodiments, the flexible support layer and the auxiliary transmission layer are spaced apart from the force-bearing portion; And / or, the electrode body layer and the auxiliary delivery layer may form a letter "V" shape during implantation and delivery.

[0010] In some embodiments, the auxiliary delivery layer further includes a limiting portion, which is integral with the second adhesive portion, and at least a portion of the limiting portion and at least a portion of the flexible support layer form a pocket structure; And / or, the first adhesive portion and the second adhesive portion are an integral structure; And / or, the material of the first adhesive portion is an organic polymer; And / or, the material of the second adhesive portion is an organic polymer; And / or, the first adhesive portion and the second adhesive portion are made of the same material.

[0011] In some embodiments, the release layer is disposed on the flexible support layer and at least partially fills the area spaced between the flexible support layer and the auxiliary transfer layer; And / or, the peeling layer is located on the auxiliary transfer layer and at least partially fills the area spaced between the auxiliary transfer layer and the flexible support layer.

[0012] In some embodiments, the peeling layer is a single-layer metal structure to achieve separation of a predetermined region between the flexible support layer and the auxiliary transfer layer; Alternatively, the release layer is a double-layer metal structure, including a metal adhesion layer and a metal bonding layer, wherein the metal adhesion layer is strongly adhered to the flexible support layer or the auxiliary transfer layer, and the metal adhesion layer and the metal bonding layer are made of different metal materials; Alternatively, the peeling layer may be a multi-layered metal structure to achieve separation of a predetermined area between the flexible support layer and the auxiliary transfer layer.

[0013] In some embodiments, the electrode body layer includes the flexible support layer, the conductive layer, and the flexible encapsulation layer arranged sequentially; the electrode body layer also includes a tear-off portion, which is used to separate at least partially the portion of the electrode body layer and the auxiliary transfer layer, excluding the first adhesive portion and the second adhesive portion, under the action of external force; The tear-off portion is disposed on the flexible support layer and / or the flexible encapsulation layer; And / or, the tear-off portion is disposed at the edge of the flexible support layer and / or the tear-off portion is disposed at the edge of the flexible encapsulation layer.

[0014] In some embodiments, the flexible electrode further includes a marking portion disposed on the flexible support layer and distributed around the contact area or the electrode contact. The marking portion is used to locate the real-time position of the electrode contact in the body when the electrode contact is implanted.

[0015] In some embodiments, the flexible electrode further includes a hollow portion, which includes a plurality of first hollow portions and a plurality of second hollow portions. The first hollow portions are disposed in the contact area, corresponding to the electrode body layer, and are offset from the electrode contact. The second hollow portions are disposed on the limiting portion, and the orthographic projection of the second hollow portion on the flexible support layer at least partially overlaps with the first hollow portion.

[0016] A second aspect of this application provides a method for fabricating a flexible electrode for a brain-computer interface, the method comprising the following steps: An auxiliary transfer layer is provided, the auxiliary transfer layer including a second adhesive portion and a limiting portion connected to the second adhesive portion; A release layer is prepared on the auxiliary transfer layer, the release layer covering at least a portion of the limiting portion; A flexible support layer is prepared in situ on the release layer, the flexible support layer covers the second adhesive portion and the release layer, and the portion of the flexible support layer corresponding to the second adhesive portion is the first adhesive portion; The conductive layer is fabricated on the flexible support layer, and the conductive layer includes a plurality of electrode contacts and a plurality of electrode pads; A flexible encapsulation layer is formed on the flexible support layer and the conductive layer, the flexible encapsulation layer covering the conductive layer and the flexible support layer; Remove the flexible encapsulation layer from the electrode contacts and electrode pads, and prepare the cutout portion; The flexible support layer is separated from the auxiliary transfer layer, while the first adhesive portion and the second adhesive portion remain connected. The limiting portion is then separated from the flexible support layer to obtain the flexible electrode.

[0017] Beneficial effects: This application provides a flexible electrode for a brain-computer interface. The flexible electrode incorporates an auxiliary delivery layer and a dissector layer. The dissector layer is positioned between the electrode body layer and the auxiliary delivery layer, separating predetermined areas of the electrode body layer and the auxiliary delivery layer to form a gap. The electrode body layer and the auxiliary delivery layer are at least partially connected to form a force-receiving portion of an external drive. The external drive can be inserted into the gap between the electrode body layer and the auxiliary delivery layer, resisting the force-receiving portion on the flexible electrode, and driving the flexible electrode to move in a predetermined direction. During implantation, a bone window with a cross-sectional shape similar to and slightly larger than that of the flexible electrode can be cut into the skull of the subject. An external drive (e.g., a flexible stainless steel ruler) is then inserted into this gap, resisting the force-receiving portion on the flexible electrode. This allows the flexible electrode to be delivered from the bone window into the skull via the external drive, thus delivering the flexible electrode to the brain surface region of interest.

[0018] Compared with existing technologies that require opening a bone window in the skull with a diameter slightly larger than the long side of the electrode cross-section (generally a bone window with a diameter of several centimeters), this flexible electrode implantation method can significantly reduce the area of ​​the bone window that needs to be cut in the skull during the electrode implantation process, thereby greatly reducing the clinical surgical risks of electrode implantation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the implantation process of the flexible electrode in some embodiments of this application; Figure 2 This is a schematic diagram of the overall structure of the flexible electrode in some embodiments of this application; Figure 3 This is a top view of the conductive layer of the flexible electrode in some embodiments of this application; Figure 4 This is a cross-sectional view of the flexible electrode in the AA direction in some embodiments of this application; Figure 5 This is a cross-sectional view of the flexible electrode in the AA direction in some other embodiments of this application; Figure 6 This is a cross-sectional view of the flexible electrode in the AA direction in some other embodiments of this application; Figure 7 This is a cross-sectional view of the flexible electrode in the AA direction in some other embodiments of this application; Figure 8 This is a cross-sectional view of the flexible electrode in the AA direction in some other embodiments of this application; Figure 9 This is a partial structural schematic diagram of the flexible electrode in some embodiments of this application; Figure 10 for Figure 9 CT imaging of a flexible electrode; Figure 11 This is a schematic diagram of the fabrication process of the flexible electrode in some embodiments of this application; Figures 12 to 19 This is a schematic diagram of the intermediate products corresponding to different stages of the fabrication process of the flexible electrode in this application.

[0021] Icon labels: 10. Flexible electrode; 100. Electrode body layer; 110. Flexible support layer; 111. First adhesive portion; 112. First cutout portion; 113. Fourth cutout portion; 120. Conductive layer; 121. Electrode contact; 122. Electrode pad; 123. Conductive wire; 130. Flexible encapsulation layer; 131. Third cutout portion; 132. Fifth cutout portion; 140. Tear-off portion; 150. Marking portion; 160. Electrode finishing layer; 200, Auxiliary transfer layer; 210, Second adhesive part; 220, Limiting part; 221, Second hollow part; 300. Peel-off layer; 400, drive component; 500, skull; 600, bone window; 700, gap; 800, base. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. Different components and technical features described in different embodiments herein can be freely combined and used with each other.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0025] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0026] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0028] Please see Figures 1 to 10 This application provides a flexible electrode 10 for a brain-computer interface, comprising an electrode body layer 100, an auxiliary transmission layer 200, and a stripping layer 300. The electrode body layer 100 is used to acquire neural signals from the cerebral cortex; combined with... Figure 1 and Figure 2 As shown, the auxiliary delivery layer 200 is at least partially connected to the electrode body layer 100 to form the force-receiving part of the external drive member 400 and to limit the external drive member 400; the dissecting layer 300 is disposed between the electrode body layer 100 and the auxiliary delivery layer 200 to separate the preset areas of the electrode body layer 100 and the auxiliary delivery layer 200, forming a gap 700. This allows the flexible electrode 10 to be implanted minimally invasively with the cooperation of the electrode body layer 100, the auxiliary delivery layer 200, and the dissecting layer 300. Specifically, after the electrode body layer 100 separates from the preset area of ​​the auxiliary delivery layer 200, the gap 700 allows the electrode body layer 100 to be flexibly delivered to the brain surface region of interest within the skull 500 through the bone window 600 on the skull 500 under the action of the external drive member 400.

[0029] It should be noted that the auxiliary transmission layer 200 is at least partially connected to the electrode body layer 100 to form the force-receiving part of the external drive member 400. For example, one end of the auxiliary transmission layer 200 may be connected to one end of the electrode body layer 100, and the other end of the auxiliary transmission layer 200 may be separated from the other end of the electrode body layer 100. The end of the auxiliary transmission layer 200 connected to the electrode body layer 100 forms the force-receiving part of the flexible electrode 10, and a gap 700 is formed between the separated parts of the auxiliary transmission layer 200 and the electrode body layer 100.

[0030] In some embodiments, the flexible electrode 10 is generally a long, thin sheet structure. Exemplarily, the length of the flexible electrode 10 ranges from 1 cm to 20 cm, the width ranges from 0.1 cm to 10 cm, and the height (i.e., the thickness) ranges from 5 μm to 1000 μm. In this way, the flexible electrode 10 can form a good conformal attachment to the surface of the cerebral cortex, greatly reducing the stimulation of the brain by the electrode implant.

[0031] In some embodiments, combined with Figure 3 and Figure 4 As shown, the electrode body layer 100 includes a flexible support layer 110, which provides support for other components in the electrode body layer 100 and serves to insulate and isolate moisture.

[0032] Optionally, the flexible support layer 110 is generally rectangular, and its thickness ranges from 5μm to 1000μm. For example, the thickness range of the flexible support layer 110 is 5μm, 10μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, and any two of the above values.

[0033] Optionally, the flexible support layer 110 is made of one or more polymer materials selected from PI (polyimide), Parylene-C (par-xylene), SU-8 (epoxy negative photoresist) or PDMS (polydimethylsiloxane), preferably PI with high biocompatibility.

[0034] Optionally, the flexible support layer 110 has a contact area and an electrode pad area disposed opposite to each other, and a conductive line area located between the contact area and the electrode pad area.

[0035] Optionally, combined Figure 2 and Figure 4 As shown, the flexible support layer 110 includes a first adhesive portion 111, which is at least partially connected to the auxiliary transfer layer 200, thereby forming a force-bearing portion on the flexible electrode 10 capable of abutting against the external drive member 400. Exemplarily, the first adhesive portion 111 is disposed near the contact area on the flexible support layer 110 and located on the side away from the electrode pad area on the flexible support layer 110. Optionally, the material of the first adhesive portion 111 is an organic polymer.

[0036] In some embodiments, combined with Figure 3 and Figure 4As shown, the electrode body layer 100 includes a conductive layer 120, which is used to acquire and transmit neural signals from the cerebral cortex. The conductive layer 120 is disposed on the side of the flexible support layer 110 facing away from the auxiliary transmission layer 200, and the flexible support layer 110 is used to support the conductive layer 120.

[0037] Optionally, the conductive layer 120 comprises one or more materials selected from titanium, chromium, gold, platinum, and silicon carbide, enabling it to conduct electricity while also maintaining good adhesion to the flexible support layer 110. Preferably, the thickness of the conductive layer 120 ranges from 0.05 μm to 10 μm, for example, the thickness ranges from 0.05 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, and any two of the above values. This allows the conductive layer 120 to transmit neural signals more stably.

[0038] Optionally, the conductive layer 120 includes a plurality of electrode contacts 121, a plurality of electrode pads 122, and a plurality of conductive lines 123. For example, the plurality of electrode contacts 121 are disposed on the contact area of ​​the flexible support layer 110, the plurality of electrode pads 122 are disposed on the electrode pad area of ​​the flexible support layer 110, and the plurality of conductive lines 123 are disposed on the conductive line area of ​​the flexible support layer 110. Each electrode contact 121 and its corresponding electrode pad 122 are electrically connected via a conductive line 123.

[0039] In other words, it can be understood that the first adhesive portion 111 of the flexible support layer 110 is located near the electrode contact 121 and away from the electrode pad 122. This helps to avoid interference of the first adhesive portion 111 with the existing conductive layer 120, simplifies the manufacturing process, and improves the structural compactness of the flexible electrode 10.

[0040] Optionally, the conductive layer 120 includes one or more electrode contacts 121 for contacting brain tissue to collect neural electrical signals within a certain range. Exemplarily, the conductive layer 120 includes multiple electrode contacts 121, with any two electrode contacts 121 spaced apart, and adjacent spaced-apart electrode contacts 121 not connected. The multiple electrode contacts 121 are arranged in an array at a certain spacing on the contact area of ​​the flexible support layer 110. Exemplarily, the size of the electrode contacts 121 ranges from 10 μm to 1000 μm; the spacing between the multiple electrode contacts 121 ranges from 50 μm to 5000 μm. Optionally, the shape of the electrode contacts 121 can be circular, rectangular, or other geometric shapes, without limitation. Optionally, the material used to fabricate the electrode contacts 121 can be one or more of titanium, chromium, gold, platinum, and silicon carbide.

[0041] Optionally, the conductive layer 120 includes one or more electrode pads 122 for connection to an external flexible printed circuit board to output neural electrical signals in parallel. Exemplarily, the conductive layer 120 includes a plurality of electrode pads 122 arranged in an array at a certain spacing on an electrode pad region on the flexible support layer 110. Exemplarily, the size of each electrode pad 122 ranges from 500 μm to 5000 μm. Exemplarily, the shape of the electrode pad 122 can be circular, rectangular, annular, or other geometric shapes, and the electrode pad 122 is provided with through holes that enable the electrodes to achieve a stable electrical connection with the printed circuit board (PCB).

[0042] Optionally, the conductive layer 120 includes one or more conductive lines 123 for transmitting neural signals collected by the electrode contacts 121 to corresponding electrode pads 122 and an external flexible printed circuit board to output neural electrical signals. Exemplarily, multiple conductive lines 123 (e.g., metal wires) are arranged at intervals on the conductive line region of the flexible support layer 110. The multiple spaced conductive lines 123 can be understood as multiple non-intersecting metal leads, with each conductive line 123 connected to an electrode contact 121 and an electrode pad 122 at both ends, forming a conductive path. The thickness of the conductive lines 123 ranges from 0.05 μm to 10 μm. The materials used to prepare the conductive lines 123 include one or more of titanium, chromium, gold, platinum, and silicon carbide.

[0043] It should be emphasized that "multiple" or "more than" in the above description refers to two or more items.

[0044] Unless otherwise specified, the following description uses the conductive layer 120 as an example, which includes multiple electrode contacts 121, multiple electrode pads 122, and multiple conductive lines 123 arranged in an array.

[0045] In some embodiments, combined with Figure 3 and Figure 4As shown, the electrode body layer 100 includes a flexible encapsulation layer 130, which covers the flexible support layer 110 and the conductive layer 120. Optionally, the flexible support layer 110, the conductive layer 120, and the flexible encapsulation layer 130 are stacked sequentially. For example, the flexible support layer 110, the conductive layer 120, and the flexible encapsulation layer 130 form a sandwich structure. The flexible support layer 110 is disposed at the bottom of the electrode body layer 100 and opposite to the auxiliary transmission layer 200. The bottom flexible support layer 110 supports the conductive layer 120 and provides insulation and moisture isolation. The middle conductive layer 120 (e.g., a metal conductive layer) is in at least partially in contact with tissue to transmit nerve signals. The top flexible encapsulation layer 130 provides insulation between channels and isolates moisture. This simplifies the structure of the electrode body layer 100 without altering the existing electrode body layer 100, maximizing the use of the existing structure and fabrication process, and reducing manufacturing costs.

[0046] Optionally, the material of the flexible encapsulation layer 130 is selected from PI (polyimide), Parylene-C (par-xylene), SU-8 (epoxy negative photoresist), or PDMS (polydimethylsiloxane), and its thickness ranges from 5 μm to 1000 μm. For example, the thickness range of the flexible encapsulation layer 130 is 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, and any two of the above values.

[0047] In some embodiments, the flexible encapsulation layer 130 covers the flexible support layer 110 and the conductive layer 120, and forms an exposed surface at the electrode contact 121. This can also be understood as the side of the electrode contact 121 facing the flexible encapsulation layer 130 being exposed. This facilitates contact between the electrode contact 121 and the tissue, improving signal stability.

[0048] In some embodiments, the flexible encapsulation layer 130 covers the flexible support layer 110 and the conductive layer 120, and forms an exposed surface at the electrode pads 122. This can also be understood as the surface of the electrode pads 122 facing the flexible encapsulation layer 130 being exposed. This facilitates electrical connection between the electrode pads 122 and external components.

[0049] In some embodiments, the flexible encapsulation layer 130 covers the flexible support layer 110 and the conductive layer 120, and only forms exposed surfaces at the electrode contacts 121 and the electrode pads 122. This facilitates increasing the area covered by the flexible encapsulation layer 130 and improving the encapsulation effect of the flexible electrode 10 in this application.

[0050] In some embodiments, combined with Figure 8 As shown, the electrode body layer 100 includes an electrode modification layer 160, and a flexible support layer 110, a conductive layer 120, a flexible encapsulation layer 130, and the electrode modification layer 160 are stacked sequentially from bottom to top. Specifically, the flexible support layer 110 is disposed at the bottom of the electrode body layer 100 and is disposed opposite to the auxiliary transmission layer 200, serving to support the conductive layer 120 and to provide insulation and moisture isolation; the conductive layer 120, located in the middle layer, is used to contact tissue and transmit nerve signals; the flexible encapsulation layer 130, located at the top layer, serves to insulate the conductive layer 120 and isolate moisture; the electrode modification layer 160 is connected to part of the conductive layer 120 and is used to increase biocompatibility, charge injection capability, and the signal-to-noise ratio of nerve signal acquisition.

[0051] Optionally, the electrode modification layer 160 covers the flexible encapsulation layer 130, the exposed surface of the electrode contact 121, and an area extending 5 μm to 50 μm beyond its edges. The electrode modification layer 160 is prepared from one or more materials selected from gold, platinum, iridium, iridium oxide, titanium nitride, poly(3,4-ethylenedioxythiophene) (PEDOT), and carbon nanotubes (CNTs). This improves the stability of the flexible electrode 10 and enhances the signal-to-noise ratio of neural signal acquisition and electrode biocompatibility.

[0052] In some embodiments, combined with Figures 1-8 As shown, the electrode body layer 100 is located above the auxiliary transfer layer 200, and the orthographic projection of the entire electrode body layer 100 lies within the contour range of the auxiliary transfer layer 200. Thus, the electrode body layer 100 can be directly fabricated on the auxiliary transfer layer 200, which helps to reduce the fabrication process.

[0053] For example, the auxiliary delivery layer 200 is integrated onto the flexible support layer 110 via in-situ reaction to form a single structure. This improves the bonding strength between the auxiliary delivery layer 200 and the flexible support layer 110, enhances the stability of the minimally invasive implanted flexible electrode 10, and simplifies the manufacturing process.

[0054] In some embodiments, the electrode body layer 100 is a high-density, ultra-thin, flexible cortical electrode, and the auxiliary delivery layer 200 is in situ integrated on the flexible support layer 110. In this way, the flexible electrode 10 can be precisely delivered to the brain surface by making a micro-slit less than 1 mm wide in the skull 500, which greatly reduces the clinical surgical risks of electrode implantation.

[0055] Optionally, the auxiliary transport layer 200 is selected from one or more of PI (polyimide), Parylene-C (par-xylene), SU-8 (epoxy-based negative photoresist), or PDMS (polydimethylsiloxane). This allows the auxiliary transport layer 200 to possess good biocompatibility. It should be noted that the auxiliary transport layer 200 needs to be able to form strong adhesion with the flexible support layer 110 at the connection point and also possess good biocompatibility.

[0056] Optionally, the thickness of the auxiliary transfer layer 200 ranges from 5 μm to 1000 μm. The outline dimensions of the auxiliary transfer layer 200 are consistent with those of the flexible electrode 10, that is, the outline dimensions of the auxiliary transfer layer 200 determine the final outline dimensions of the flexible electrode 10.

[0057] In some embodiments, combined Figures 1-4 As shown, the auxiliary transfer layer 200 includes a second adhesive portion 210, which is connected to the first adhesive portion 111, so that the electrode body layer 100 and the auxiliary transfer layer 200 form a force-bearing portion that can be supported by the external drive member 400.

[0058] Understandably, the first adhesive portion 111 and the second adhesive portion 210 are connected directly opposite each other, so that the flexible support layer 110 and the auxiliary transmission layer 200 are at least partially connected, thereby forming a force-bearing portion on the flexible electrode 10 that can abut against the external driving member 400 (e.g., an elastic stainless steel ruler). At the same time, the portion of the flexible support layer 110 near the force-bearing portion (i.e., at least the portion of the flexible support layer 110 near the first adhesive portion 111) and the portion of the auxiliary transmission layer 200 located on the same side as the force-bearing portion (i.e., at least the portion of the limiting portion 220 near the second adhesive portion 210) are spaced apart, thereby forming a gap 700 between the auxiliary transmission layer 200 and the flexible support layer 110 (or the electrode body layer 100), so that the auxiliary transmission layer 200 and the flexible support layer 110 can limit the external driving member 400 located therein.

[0059] When it is necessary to implant the flexible electrode 10 of this application into the body, a bone window 600 with a cross-sectional shape similar to and slightly larger than that of the flexible electrode 10 can be cut in the skull 500 of the subject. Then, an external drive 400 (e.g., an elastic stainless steel ruler) is inserted into the gap 700 formed between the flexible support layer 110 and the auxiliary delivery layer 200, and the external drive 400 is abutted against the connection end of the second adhesive portion 210 and the first adhesive portion 111. The flexible electrode 10 is delivered from the bone window 600 on the skull 500 into the skull 500 through the external drive 400, so as to deliver the flexible electrode 10 to the brain surface region of interest. Compared with the existing technology that requires opening a bone window 600 on the skull 500 with a diameter slightly larger than the long side of the electrode cross-section (generally a bone window 600 with a diameter of several centimeters), the implantation method of this flexible electrode 10 can significantly reduce the area of ​​the bone window 600 that needs to be cut on the skull 500 during the electrode implantation process, thereby greatly reducing the clinical surgical risk of electrode implantation.

[0060] For example, the first adhesive portion 111 is disposed at one end of the flexible support layer 110, and the second adhesive portion 210 is disposed at one end of the auxiliary transfer layer 200. The first adhesive portion 111 and the second adhesive portion 210 form a connection end, and the flexible support layer 110 and the auxiliary transfer layer 200 are spaced apart except for the portion forming the connection end.

[0061] For example, the second adhesive portion 210 is disposed at one end of the auxiliary transfer layer 200, directly opposite the first adhesive portion 111 of the flexible support layer 110. The auxiliary transfer layer 200 and the flexible support layer 110 are in direct contact at the first adhesive portion 111 and the second adhesive portion 210 to form an integral structure. The area on the auxiliary transfer layer 200 other than the second adhesive portion 210 and the area on the flexible support layer 110 other than the first adhesive portion 111 are completely separated. It can be understood that the outer edge of the end of the flexible electrode 10 where the electrode contact 121 is located (for example, a few millimeters wide area on the side of the contact area away from the pad area) is the tightly connected end (that is, the area where the flexible support layer 110 and the auxiliary transfer layer 200 are connected to form the force-bearing part), while other areas are completely separated.

[0062] It is particularly emphasized that, through the aforementioned configuration, the electrode body layer 100 and the auxiliary delivery layer 200 of the flexible electrode 10 in this application can form a "V" shape during implantation and delivery. This facilitates further simplification of the structure and fabrication process of the flexible electrode 10, reduces fabrication costs, and makes it easier to use.

[0063] In some embodiments, the auxiliary delivery layer 200 further includes a limiting portion 220, the first adhesive portion 111 is connected to the second adhesive portion 210, the limiting portion 220 and the second adhesive portion 210 are an integral structure, and at least a portion of the limiting portion 220 and at least a portion of the flexible support layer 110 form a pocket structure.

[0064] It should be noted that the "pocket" structure here can be understood as a force-bearing part that can abut against the external driving member 400 and an insertion port that communicates with the force-bearing part between the limiting part 220 and the flexible support layer 110. The external driving member 400 can enter the interior of the flexible electrode 10 through the insertion port and abut against the force-bearing part to drive the force-bearing part, thereby transmitting the contact area of ​​the flexible electrode 10 to the target position. The "pocket" structure can be a letter V-shaped pocket with one end connected (only the connecting end is connected), or it can be a pocket with three sides connected (i.e., in addition to the connecting end connection, at least part of the limiting part 220 is connected to at least part of the flexible support layer 110). The side length of the connecting end of the three-sided connected pocket structure can be flexibly adjusted, as long as it can be combined with the auxiliary transmission layer 200 during the structure processing, and the preset area of ​​the flexible support layer 110 and the auxiliary transmission layer 200 can be separated during the structure release, without causing any adverse effects on the normal operation of the flexible electrode 10.

[0065] For example, the first adhesive portion 111 is disposed at one end of the flexible support layer 110, and the second adhesive portion 210 is disposed at one end of the auxiliary transmission layer 200. The first adhesive portion 111 and the second adhesive portion 210 are connected opposite each other to form a force-bearing portion. The other end of the flexible support layer 110 away from the first adhesive portion 111 is disposed opposite to the other end of the auxiliary transmission layer 200 (i.e., the limiting portion 220) and forms an insertion port. That is, one end of the flexible electrode 10 is a connecting end to form a force-bearing portion, and the other end is separated to form an insertion port. The external driving member 400 can enter the interior of the flexible electrode 10 through the insertion port and resist the force-bearing portion to drive the force-bearing portion so that the electrode contact of the flexible electrode 10 is transmitted to the target position.

[0066] Optionally, the first adhesive portion 111 and the second adhesive portion 210 are an integral structure. Further, the first adhesive portion 111 and the second adhesive portion 210 are formed into an integral structure through an in-situ reaction. This is beneficial for improving the adhesion between the flexible support layer 110 and the conductive layer 120, and for improving the stability of the flexible electrode 10.

[0067] Optionally, the material of the first adhesive portion 111 is an organic polymer, and the material of the second adhesive portion 210 is an organic polymer. Further, the first adhesive portion 111 and the second adhesive portion 210 are made of the same material. For example, the materials of the first adhesive portion 111 and the second adhesive portion 210 are both polyimide. Both the first adhesive portion 111 and the second adhesive portion 210 are prepared from a polyimide precursor solution. The precursor solution of the second adhesive portion 210 is first partially cured, and then the precursor solution of the first adhesive portion 111 is coated onto the partially cured second adhesive portion 210. Simultaneously, heating is applied to allow both the second adhesive portion 210 and the first adhesive portion 111 to fully cure, forming an integral structure.

[0068] In some other embodiments of this application, the materials of the first adhesive portion 111 and the second adhesive portion 210 may also be different, as long as the materials of the first adhesive portion 111 and the second adhesive portion 210 can chemically react to form an integral structure. In some other embodiments of this application, the first adhesive portion 111 and the second adhesive portion 210 may also be bonded together with an adhesive (e.g., bio-adhesive) to form an integral structure.

[0069] In some embodiments, combined with Figures 4 to 7 As shown, Figures 4 to 7 The main difference lies in the structure of the release layer 300. The release layer 300 is disposed on the flexible support layer 110 and at least fills the area spaced between the flexible support layer 110 and the auxiliary transfer layer 200; and / or, the release layer 300 is located on the auxiliary transfer layer 200 and at least partially fills the area spaced between the auxiliary transfer layer 200 and the flexible support layer 110.

[0070] Understandably, the release layer 300 is used to separate predetermined areas on the flexible support layer 110 and the auxiliary transfer layer 200. During structural processing, the release layer 300 is disposed between the flexible support layer 110 and the auxiliary transfer layer 200, i.e., it fills the spaced area between the flexible support layer 110 and the auxiliary transfer layer 200. During structural release, after the release layer 300 is separated by external force or chemical etching, its structure may remain intact (e.g., under mechanical peeling), or it may be partially removed. In some special cases, it may be completely removed. It is important to understand flexibly the specific structures corresponding to the two different states of the release layer 300 during structural processing and structural release.

[0071] In some embodiments, please combine Figure 4As shown, the area of ​​the auxiliary transfer layer 200 except for the second adhesive portion 210 is covered by the peeling layer 300. The area of ​​the auxiliary transfer layer 200 except for the second adhesive portion 210 can be completely separated from the area of ​​the flexible support layer 110 except for the first adhesive portion 111 to form a gap 700.

[0072] It is particularly emphasized that in some embodiments, the flexible support layer 110 and the auxiliary transfer layer 200 are made of the same polymer material, and the release layer 300 is a metal release layer. By adding a metal release layer, the uniformity of bonding between polymers of the same material can be disrupted. That is, the bonding force F1 between the interface of the release layer 300 and the flexible support layer 110, and the bonding force F2 between the interface of the release layer 300 and the auxiliary transfer layer 200 are much smaller than the bonding force F between the interface of the flexible support layer 110 and the auxiliary transfer layer 200 when the release layer 300 is not present. At the same time, it is convenient to use the properties of different materials to distinguish and process them. Based on this, the separation of the preset area between the flexible support layer 110 and the auxiliary transfer layer 200 can be achieved by external force or chemical etching process to form a gap 700.

[0073] It is particularly emphasized that in some embodiments, the flexible support layer 110 and the auxiliary transfer layer 200 may be polymers of different materials, and the release layer 300 is a metal release layer. The bonding force F1 between the release layer 300 and the interface of the flexible support layer 110 of different materials is different from the bonding force F2 between the release layer 300 and the auxiliary transfer layer 200. The separation of the preset area between the flexible support layer 110 and the auxiliary transfer layer 200 can be achieved by external force or chemical etching process to form a gap 700.

[0074] Specifically, the release layer 300 is a single-layer metal structure to achieve separation of a predetermined region between the flexible support layer 110 and the auxiliary transfer layer 200. For example, at least a portion of the release layer 300 can be removed by external force or chemical etching.

[0075] For example, such as Figure 6 and Figure 7As shown, the release layer 300 is a single-layer metal structure. The flexible support layer 110 and the auxiliary transfer layer 200 are made of the same highly biocompatible polymeric organic material, designed to have weak adhesion to the single-layer metal structure. Therefore, in areas where the release layer 300 exists, the auxiliary transfer layer 200 and the flexible support layer 110 can be easily separated under external force (e.g., mechanical peeling). However, in the area where the second adhesive portion 210 is located (e.g., one end of the auxiliary transfer layer 200), there is no release layer 300. The second adhesive portion 210 and the first adhesive portion 111 on the flexible support layer 110 are directly contacted and integrally formed, creating a strong connection. This achieves separation of the predetermined area between the flexible support layer 110 and the auxiliary transfer layer 200, forming a gap 700. It should be noted that in this case, the release layer 300 of the single-layer metal structure may ultimately exist (by controlling the position and angle under external force) or may not exist, such as... Figure 6 and Figure 7 As shown, this is to prevent the release layer 300, which has weaker adhesion than the single-layer metal structure between polymer organic materials, from accidentally falling off during implantation or delivery, thus threatening the patient's life.

[0076] For example, combined Figure 6 As shown, the release layer 300 is a single-layer metal structure. The flexible support layer 110 and the auxiliary transfer layer 200 are made of different highly biocompatible polymeric organic materials. The single-layer metal structure has a weaker adhesion to either the flexible support layer 110 or the auxiliary transfer layer 200, but a stronger adhesion to the other. Therefore, in the area where the release layer 300 exists, the auxiliary transfer layer 200 and the flexible support layer 110 can be easily separated along the side with weaker adhesion under external force (e.g., mechanical peeling), while remaining on the side with stronger adhesion. In the area where the second adhesive portion 210 is located (e.g., one end of the auxiliary transfer layer 200), there is no release layer 300. The second adhesive portion 210 and the first adhesive portion 111 on the flexible support layer 110 are directly contacted and integrally formed, creating a strong connection. This achieves the separation of the predetermined area between the flexible support layer 110 and the auxiliary transfer layer 200, forming a gap 700.

[0077] For example, the flexible support layer 110 and the auxiliary transfer layer 200 can be made of the same or different polymer materials, and the release layer 300 is a single-layer metal structure. The release layer 300 is removed using a chemical etching process, but the flexible support layer 110 and the auxiliary transfer layer 200 are unaffected. The release layer 300 can be completely etched, combined with... Figure 6 and Figure 7As shown, in the fabricated flexible electrode 10, the auxiliary transfer layer 200 and the flexible support layer 110 are separated in a predetermined region due to the complete etching of the release layer 300, thus forming a gap 700. It is understood that the final fabricated flexible electrode 10 does not contain the release layer 300; the corresponding release layer 300 is removed by a chemical etching process. (See reference...) Figure 7 As shown.

[0078] It should be noted that the separation of the pre-defined region between the flexible support layer 110 and the auxiliary delivery layer 200 can be achieved. The peeling layer 300 of the prepared single-layer metal structure may or may not be present. It is preferred that the peeling layer 300 of the single-layer metal structure is not present, so as to avoid accidental detachment during the implantation and delivery process or operation of the flexible electrode 10, which could threaten the patient's life safety.

[0079] Specifically, such as Figure 4 and Figure 5 As shown, the release layer 300 is a double-layer metal structure, including a metal adhesion layer and a metal bonding layer. The metal adhesion layer is strongly adhered to the flexible support layer 110 or the auxiliary transfer layer 200. The metal adhesion layer and the metal bonding layer are made of different metal materials. For example, the metal bonding layer is used to remove at least part of the metal bonding layer by external force or by chemical etching to achieve separation of a predetermined area between the flexible support layer 110 and the auxiliary transfer layer 200.

[0080] For example, combined Figure 4 and Figure 5 As shown, the flexible support layer 110 and the auxiliary transfer layer 200 can be made of the same or different polymer materials, and the release layer 300 is a double-layer metal structure. Specifically, the double-layer metal structure release layer 300 includes a metal adhesion layer and a metal bonding layer.

[0081] Optionally, the metal adhesion layer is at the bottom (i.e., the metal adhesion layer faces the auxiliary transfer layer 200), and the metal bonding layer is at the top (the relative positions of the two can be interchanged, as long as the metal adhesion layer has strong adhesion to the flexible support layer 110 or the auxiliary transfer layer 200, and the metal bonding layer has weak adhesion to the corresponding auxiliary transfer layer 200 or the flexible support layer 110, which is weaker than the adhesion between the metal bonding layer and the metal adhesion layer); the function of the metal bonding layer is to combine the flexible support layer 110 and the auxiliary transfer layer 200 into one during structural processing, and to facilitate the separation of the preset area between the flexible support layer 110 and the auxiliary transfer layer 200 by external force (such as physical mechanical peeling) during structural release. With this configuration, after external force is applied (such as physical mechanical dissection), the pre-defined area between the flexible support layer 110 and the auxiliary transmission layer 200 is separated through the metal bonding layer. The entire dissection layer 300 can be tightly adhered to the auxiliary transmission layer 200 or the flexible support layer 110, which is strongly adhered to the metal adhesion layer, through the metal adhesion layer. This can effectively prevent the dissection layer 300 from accidentally falling off and entering the cranium after electrode implantation, thus avoiding surgical risks.

[0082] Specifically, when separated by external force (e.g., mechanical peeling), the weak adhesion between the flexible support layer 110 or auxiliary transfer layer 200 and the metal bonding layer allows the flexible support layer 110 and the auxiliary transfer layer 200 to separate. That is, the adhesive force between the metal adhesive layer and the flexible support layer 110 or auxiliary transfer layer 200, and the adhesive force between the metal adhesive layer and the metal bonding layer are greater than or much greater than the adhesive force between the flexible support layer 110 or auxiliary transfer layer 200 and the metal bonding layer. Thus, under external force (e.g., mechanical peeling), the peeling layer 300 is still a double-layer metal structure, but the interface between the flexible support layer 110 and the metal bonding layer is peeled off, achieving the separation of the flexible support layer 110 and the auxiliary transfer layer 200 to form a gap 700.

[0083] For example, combined Figure 4As shown, the release layer 300 is a double-layer metal structure, including a metal adhesion layer and a metal bonding layer, which are made of different metal materials. The metal adhesion layer is at the bottom (i.e., the metal adhesion layer faces the auxiliary transfer layer 200), and the metal bonding layer is at the top (the relative positions of the two can be interchanged, as long as there is strong adhesion between the metal adhesion layer and the flexible support layer 110 or the auxiliary transfer layer 200). The function of the metal bonding layer is to bond the flexible support layer 110 and the auxiliary transfer layer 200 together during structure processing, and to facilitate the separation of the predetermined area between the flexible support layer 110 and the auxiliary transfer layer 200 by at least partially removing the metal bonding layer through a chemical etching process during structure release. With this configuration, after the chemical etching process, the metal bonding layer separates the preset area between the flexible support layer 110 and the auxiliary transfer layer 200 without damaging the normal structure and normal working performance of the entire flexible electrode 10. The metal adhesion layer can continue to adhere tightly to the auxiliary transfer layer 200 or the flexible support layer 110, which is strongly adhered to the metal adhesion layer. This can effectively avoid the risk of the metal adhesion layer accidentally falling off and entering the cranium after electrode implantation, thus preventing surgical risks.

[0084] To further clarify, when using a chemical etching process to remove at least a portion of the metal bonding layer to achieve separation of the predetermined region between the flexible support layer 110 and the auxiliary transfer layer 200, the metal adhesion layer is not etched, but at least a portion of the metal bonding layer is etched. The unetched metal adhesion layer can cover either the flexible support layer 110 or the auxiliary transfer layer 200, thereby achieving separation of the flexible support layer 110 and the auxiliary transfer layer 200, excluding the connecting portion. It is understood that the metal bonding layer does not need to be completely etched; that is, a portion of the metal bonding layer may remain after etching, as long as the flexible support layer 110 and the auxiliary transfer layer 200 can be separated according to the predetermined region.

[0085] Optionally, the metal adhesion layer can be made of materials such as titanium, chromium, titanium nitride, and silicon carbide, with a thickness ranging from 5 nm to 50 nm. The metal bonding layer can be made of materials such as gold, platinum, copper, nickel, and titanium, with a thickness ranging from 50 nm to 5000 nm.

[0086] Specifically, the release layer 300 is a multi-layered metal structure to achieve separation of a predetermined region between the flexible support layer 110 and the auxiliary transfer layer 200. For example, at least a portion of the release layer 300 can be removed by external force or by chemical etching.

[0087] It should be noted that the single-layer metal structure and the double-layer metal structure are the basic structures of the release layer 300. In practical applications, if a release layer 300 with a more stable connection and better release effect is required, the release layer 300 can be set with a multi-layer metal structure. The multi-layer metal structure can be stacked sequentially, or it can be a base metal structure with one layer as the base and two or more layers of metal structures arranged side by side and interlaced. As long as it can be separated from the preset area between the flexible support layer 110 and the auxiliary transfer layer 200 by external force or chemical etching process, as described above with the single-layer metal structure or double-layer metal structure, the separation principle is the same, the difference lies in the number of metal structure layers and the combination method of the release layer 300.

[0088] In some embodiments, please refer to Figure 1 and Figure 2 The electrode body layer 100 further includes a tearing portion 140, which is used to separate, at least partially, the portion of the electrode body layer 100 and the auxiliary transfer layer 200, excluding the first adhesive portion 111 and the second adhesive portion 210, under the action of external force (e.g., mechanical peeling).

[0089] Specifically, a tear-off portion 140 is provided on the electrode body layer 100. The tear-off portion 140 serves to provide a force-bearing fulcrum or to facilitate the application of external forces. When it is necessary to separate a portion of the electrode body layer 100 and the auxiliary transmission layer 200, the electrode body layer 100 and the auxiliary transmission layer 200 can be separated by pulling the tear-off portion 140 in a preset direction.

[0090] For example, combined Figures 1 to 4 As shown, the electrode body layer 100 includes the flexible support layer 110, the conductive layer 120, and the flexible encapsulation layer 130 arranged sequentially, with the tear-off portion 140 disposed on the flexible support layer 110 and / or the flexible encapsulation layer 130. Further, the tear-off portion 140 is disposed at the edge of the flexible support layer 110 and / or at the edge of the flexible encapsulation layer 130. This facilitates the easy separation of the electrode body layer 100 and the auxiliary transfer layer 200 by pulling the tear-off portion 140 under external force, while avoiding interference with the original structure caused by adding the tear-off portion 140 to the electrode body layer 100.

[0091] Optionally, the tear-off portion 140 can be an arc-shaped and / or rectangular protrusion distributed along the outer contour edge of the pad area, which satisfies the requirement of not damaging the electrode pad 122 while providing sufficient force space for mechanical peeling devices such as external peeling equipment (e.g., tweezers). The protrusion range and width of the tear-off portion 140 do not exceed the boundary of the auxiliary transfer layer 200. The tear-off portion 140 can be integrally formed on the electrode body layer 100 during the fabrication of the electrode body layer 100. The material of the tear-off portion 140 can be the same as that of the flexible support layer 110 or the flexible encapsulation layer 130. The number of tear-off portions 140 can be one or more. For example, there can be multiple tear-off portions 140, with at least one tear-off portion 140 disposed at the end of the flexible support layer 110 or the flexible encapsulation layer 130 away from the electrode contact 121. The multiple tear-off sections 140 ensure that if one of them is accidentally damaged and cannot function properly, the other tear-off sections 140 can ensure that the electrode body layer 100 and the auxiliary transfer layer 200 can be separated in the preset area under the action of mechanical peeling force.

[0092] In some embodiments, combined with Figure 4 , Figure 9 as well as Figure 10 As shown, the flexible electrode 10 further includes a marking portion 150, which is disposed on the flexible support layer 110. Exemplarily, the marking portion 150 is distributed around the contact area or the electrode contact 121, and is used to locate the real-time position of the electrode contact 121 within the body when the electrode contact 121 is implanted.

[0093] For example, the marking unit 150 can be a metal block that can display single or combined patterns under the action of a transmission imaging device (such as X-ray, CT, or MRI equipment) to achieve the function of marking and / or positioning. The marking unit 150 displays clear single or combined patterns under the action of the transmission imaging device, and the patterns can be scale lines, directional patterns, triangles, circles, rings, squares, wavy lines, etc.

[0094] Understandably, the marking part 150 is disposed on the flexible support layer 110 and close to the electrode contact 121, which helps to make the structure of the flexible electrode 10 more compact and improves the positioning accuracy.

[0095] Optionally, the marking portion 150 may be composed of multiple metal blocks, which are encapsulated between the flexible support layer 110 and the flexible encapsulation layer 130. Each metal block is required to be larger than the resolution of a computed tomography (CT) or magnetic resonance imaging (MRI) device, and to be clearly visible relative to the electrode body layer 100. Its typical feature size is greater than 500 nm, ranging from 500 nm to 5000 μm, preferably 50 μm to 1000 μm. Further, the multiple metal blocks are arranged around the electrode contact 121, and there is a certain relative geometric positional relationship between the multiple metal blocks and the electrode contact 121, such as an array with progressively increasing or decreasing sizes, or a uniformly distributed array at predetermined distances. This allows for accurate determination of the position and orientation of the electrode contact 121 by observing the positions of the metal blocks.

[0096] Optionally, each metal block can consist of a "metal adhesion layer + metal layer". The metal adhesion layer can be made of materials such as titanium, chromium, titanium nitride, or silicon carbide, with a thickness ranging from 5 nm to 50 nm. Its function is to increase the adhesion between the metal block and the flexible electrode support layer 110. The metal layer can be made of materials such as gold, platinum, iridium, or nickel-titanium alloys, which have high atomic density or magnetic properties, and a thickness ranging from 0.5 nm to 5000 μm. Its function is to enable clearer imaging of the metal block under CT or MRI equipment.

[0097] In some embodiments, the flexible electrode 10 includes a hollow portion to improve the flexibility of the flexible electrode 10, reduce the bending stiffness of the flexible electrode 10 in contact with the cerebral cortex, enable the flexible electrode 10 to better adhere to the brain surface, reduce long-term damage to brain tissue, promote brain cleanliness and normal function, help reduce the abnormal deposition and aggregation of harmful proteins, reduce the risk of other brain diseases, and achieve a stable electrical connection with external devices (such as printed circuit boards (PCBs)).

[0098] Optionally, combined Figure 2 and Figure 4As shown, the cutout portion includes a plurality of first cutout portions 112. Each first cutout portion 112 is disposed within the contact area of ​​the flexible support layer 110, correspondingly penetrating the flexible support layer 110, the conductive layer 120, and the flexible encapsulation layer 130, and is offset from the electrode contact 121. Further, the first cutout portions 112 are offset from the electrode contact 121 and the conductive line 123. For example, at least a portion of the first cutout portions 112 is disposed between two adjacent electrode contacts 121. The size of the first cutout portion 112 mainly depends on the size of the contact area and the distance between two adjacent contacts; its specific size is not limited, as long as it is offset from at least a portion of the electrode contact 121 and at least a portion of the conductive line 123. For example, the first cutout portion 112 may be completely offset from the electrode contact 121 and the conductive line 123. By setting the first hollow part 112, the flexibility of the electrode body layer 100 and the flexible electrode 10 is improved, and the bending stiffness of the contact area between the flexible electrode 10 and the cerebral cortex is reduced, so that the flexible electrode 10 can better adhere to the brain surface and reduce the damage to brain tissue caused by long-term use.

[0099] Optionally, combined Figure 2 and Figure 4 As shown, the hollow portion also includes several second hollow portions 221, which are disposed on the limiting portion 220. The orthographic projection of the second hollow portion 221 on the flexible support layer 110 at least partially overlaps with the first hollow portion 112. By setting the second hollow portions 221 to work in conjunction with the first hollow portion 112, it is beneficial to improve the flexibility of the auxiliary transmission layer 200 and the flexible electrode 10, further reduce the bending stiffness of the contact area between the flexible electrode 10 and the cerebral cortex, so that the flexible electrode 10 can better adhere to the brain surface, reduce the damage to brain tissue caused by long-term use, and at the same time, effectively promote the flow of cerebrospinal fluid near the auxiliary transmission layer 200 and especially around the entire implantation site of the flexible electrode 10, maintain brain health, promote brain cleanliness and normal function, help reduce the abnormal deposition and accumulation of harmful proteins, and reduce the risk of other brain diseases.

[0100] Preferably, in some embodiments, such as Figure 4 As shown, the orthographic projection of the second hollow portion 221 onto the flexible support layer 110 completely overlaps with the outline of the first hollow portion 112. This arrangement helps to provide sufficient channels or space, effectively promoting the flow of cerebrospinal fluid around the implantation site of the flexible electrode 10, maintaining brain health, promoting brain cleanliness and normal function, helping to reduce the abnormal deposition and accumulation of harmful proteins, and lowering the risk of other brain diseases.

[0101] In some embodiments, when the cutout portion includes a plurality of second cutout portions 221, and the second cutout portions 221 are disposed on the limiting portion 220, the area on the auxiliary transfer layer 200 other than the second adhesive portion 210 and the second cutout portions 221 is covered by the release layer 300. Exemplarily, the release layer 300 is disposed on the flexible support layer 110 and covers the area on the flexible support layer 110 that is spaced apart from the auxiliary transfer layer 200. Also exemplaryly, the release layer 300 is located on the auxiliary transfer layer 200 and covers the area on the auxiliary transfer layer 200 that is pre-spaced apart from the flexible support layer 110.

[0102] Specifically, when the release layer 300 is disposed above the auxiliary transfer layer 200 and covers all areas of the auxiliary transfer layer 200 except for the second adhesive portion 210 and the second cutout portion 221, the second adhesive portion 210 is exposed and not covered by the release layer 300, allowing the first adhesive portion 111 of the flexible support layer 110 located on the release layer 300 to directly contact the second adhesive portion 210 to form an integral structure. The purpose of exposing the area where the second cutout portion 221 is located is to allow the subsequent etching process for forming the electrode contour to penetrate the auxiliary transfer layer 200 at this location, thereby forming the second cutout portion 221 on the auxiliary transfer layer 200.

[0103] In some embodiments, combined with Figure 4 As shown, the cutout portion also includes several third cutout portions 131. The third cutout portions 131 are disposed on the flexible encapsulation layer 130 and correspond to a single electrode contact 121. The size of a single third cutout portion 131 is slightly smaller than the size of the electrode contact 121, with the purpose of exposing the electrode contact 121 in the corresponding conductive layer 120 to collect neural electrical signals.

[0104] In some embodiments, combined with Figure 4 As shown, the cutout portion also includes a number of fourth cutout portions 113 and a number of fifth cutout portions 132, which are respectively disposed in the area where the electrode pads are located. The corresponding single fourth cutout portion 113 and single fifth cutout portion 132 together form a through hole that penetrates the electrode body layer 100 and external equipment (such as printed circuit board (PCB)) to achieve a stable circuit connection.

[0105] Specifically, the through-hole penetrates the electrode pad 122, which is annular. The inner diameter of the electrode pad 122 is the same as the diameter of the fourth cutout 113 penetrating the flexible support layer 110 and the conductive layer 120. The outer diameter of the annular electrode pad 122 is 2μm to 50μm larger than the inner diameter, and is the same as the diameter of the fifth cutout 132 penetrating the flexible encapsulation layer 130. This arrangement exposes the electrode pad 122 and simultaneously enables a stable electrical connection between the electrode body layer 100 (i.e., the electrode pad 122) and external devices (e.g., printed circuit boards (PCBs)).

[0106] The second aspect of this application also provides a method for preparing a flexible electrode; please refer to [link to relevant documentation]. Figures 11 to 19 The preparation method includes the following steps: S10 provides a substrate 800 on which an auxiliary transport layer 200 is prepared.

[0107] For example, step S11 provides a substrate 800.

[0108] Furthermore, combined Figure 12 As shown, the substrate 800 is made of any one of silicon nitride, silicon, or quartz glass. The substrate 800 can be four-inch, six-inch, or eight-inch in size. The substrate 800 is cleaned by ultrasonic or heated immersion in a cleaning solution. In some examples, the cleaning solution includes acetone, isopropanol, ethanol, and deionized water. In some examples, the cleaning solution includes a mixture of concentrated sulfuric acid and hydrogen peroxide, hydrofluoric acid solution, a mixture of ammonia and hydrogen peroxide, and a mixture of concentrated hydrochloric acid and hydrogen peroxide.

[0109] For example, step S12 involves preparing an auxiliary transport layer 200 on a substrate 800.

[0110] Specifically, in combination Figure 13 As shown, the auxiliary transfer layer 200 covers at least one side of the substrate 800. The auxiliary transfer layer 200 is applied to the substrate 800 by spin coating, spraying, or chemical vapor deposition. The auxiliary transfer layer 200 is made of a material selected from PI, Parylene-C, SU-8, or PDMS, and its thickness ranges from 5 μm to 1000 μm. Preferably, the auxiliary transfer layer 200 is made of PI, which is cured by heating to form a reliable support, with a selectable temperature range of 135°C to 450°C.

[0111] In some examples, the auxiliary delivery layer 200 is made of polyimide (PI). After its precursor solution is spin-coated onto the surface of the substrate 800 at a speed of 500-5000 rpm, it can be cured at a temperature below its complete curing temperature (350°C). Preferably, the spin speed is 2000 rpm. Under these conditions, the thickness of the auxiliary delivery layer 200 is 8 μm to 15 μm. This ensures that after the auxiliary delivery layer 200 and the flexible support layer 110 separate, the auxiliary delivery layer 200 will not curl up and affect the minimally invasive implantation operation. It also ensures that the overall thickness of the final product is suitable after being released from the substrate 800, reducing the implantation risk. In addition, the auxiliary delivery layer 200 cured at a lower temperature will not dissolve or be damaged by acetone, N-methylpyrrolidone (NMP), or photoresist developer in subsequent processing steps. Furthermore, it can maintain sufficient surface activity and form a strong bond between the flexible support layer 110 and the auxiliary delivery layer 200 at the connection point.

[0112] It is particularly emphasized that, in some embodiments, the auxiliary transfer layer 200 includes a second adhesive portion 210 and a limiting portion 220 connected to the second adhesive portion 210. One end of the auxiliary transfer layer 200 is the second adhesive portion 210, and the portion of the auxiliary transfer layer 200 other than the second adhesive portion 210 is the limiting portion 220. Of course, in other embodiments of this application, the second adhesive portion 210 may also be disposed at other positions on the auxiliary transfer layer 200, which is not limited here. The structure of the auxiliary transfer layer 200 can also refer to the description above, and will not be repeated here.

[0113] S20. A release layer 300 is prepared on the auxiliary transfer layer 200.

[0114] Specifically, in combination Figure 14 As shown, the peeling layer 300 covers at least a portion of the limiting portion 220.

[0115] For example, the release layer 300 is a metal release layer. Further, the release layer 300 covers at least a portion of the limiting portion 220. Specifically, the release layer 300 covers all areas on the surface of the auxiliary transfer layer 200 except for the second adhesive portion 210 and the second cutout portion 221. This facilitates the easy separation of the areas on the auxiliary transfer layer 200, excluding the second adhesive portion 210 and the second cutout portion 221, from the flexible support layer 110.

[0116] For example, the patterning process for forming the area covered by the release layer 300 is at least one of a metal lift-off process, a dry etching process, or a wet etching process.

[0117] For example, the release layer 300 can be prepared by magnetron sputtering, electron beam evaporation or chemical electroplating.

[0118] It is particularly important to note that the release layer 300 can be a single-layer metal structure, a double-layer metal structure, or a multi-layer metal structure.

[0119] For example, the release layer 300 is a single-layer metal structure. Its preparation process can be as follows: spin-coating negative photoresist on the surface of the auxiliary transfer layer 200, exposing and developing it to expose the area to be covered by the release layer 300; then treating the exposed area of ​​the photoresist with oxygen plasma or a mixed plasma of oxygen and argon; then preparing one or more thin films of titanium, chromium, silicon carbide, gold or platinum by electron beam evaporation; and finally removing the photoresist by a lift-off process to form the final release layer 300.

[0120] For example, the release layer 300 is a double-layer metal structure. The release layer 300 is formed by depositing a metal adhesion layer and a metal bonding layer in two consecutive deposits. That is, the release layer 300 includes a metal adhesion layer and a metal bonding layer.

[0121] Specifically, taking a double-layer metal structure as an example, the preparation process of the release layer 300 can be achieved by treating the surface of the auxiliary transfer layer 200 with oxygen plasma or a mixed plasma of oxygen and argon. A metal adhesion layer is prepared by magnetron sputtering; the material used for the metal adhesion layer includes at least one of titanium, chromium, and silicon carbide. Then, a metal bonding layer is prepared on the metal adhesion layer by magnetron sputtering; the material used for the metal bonding layer includes at least one of gold, platinum, nickel, and copper. Positive photoresist is spin-coated onto the surface of the magnetron sputtered film, and after exposure and development, the photoresist forms the required shape for the release layer 300. The shape of the release layer 300 is transferred to the magnetron sputtered film layer (i.e., the composite double-layer metal structure formed by the metal adhesion layer and the metal bonding layer) using dry etching or wet etching processes, forming the final release layer 300; finally, the photoresist is removed.

[0122] For example, the metal release layer is a multi-layer metal structure. Based on the aforementioned double-layer metal release layer 300, one or more metal adhesion layers and / or one or more metal bonding layers can be repeatedly deposited between the metal adhesion layer and the metal bonding layer to enhance the function of the single-layer metal adhesion layer and the single-layer metal bonding layer. Specifically, the preparation process is similar to that of the double-layer metal release layer 300, the difference being that the number of times the repeated magnetron sputtering process is used to prepare the metal adhesion layer and the metal bonding layer, as well as the metal material used, can be flexibly adjusted according to different requirements.

[0123] It should be noted that plasma treatment can increase the surface roughness and surface activity of the auxiliary transfer layer 200, thereby improving the bonding force between the release layer 300 and the auxiliary transfer layer 200, and thus enhancing the long-term stability of the flexible electrode 10 in vivo. Furthermore, the release layer 300 and the auxiliary transfer layer 200 prepared by magnetron sputtering have even better bonding force.

[0124] S30. A flexible support layer 110 is prepared in situ on the peeling layer 300.

[0125] Specifically, in combination Figure 15 As shown, the flexible support layer 110 covers the second adhesive portion 210 and the release layer 300; the portion of the flexible support layer 110 corresponding to the second adhesive portion 210 is the first adhesive portion 111.

[0126] In some embodiments of this application, after preparing the release layer 300 and before preparing the flexible support layer 110, the preparation method further includes: treating the area on the surface of the auxiliary transfer layer 200 not covered by the release layer 300 with plasma. This helps to improve the bonding force between the auxiliary transfer layer 200 and the subsequent flexible support layer 110, thereby improving the reliability of the electrode delivery structure.

[0127] For example, the area on the surface of the auxiliary transfer layer 200 not covered by the stripping layer 300 is treated with oxygen plasma or a mixed plasma of oxygen and argon.

[0128] In some embodiments of this application, the flexible support layer 110 is applied to the surface of the release layer 300 by spin coating, spraying, or chemical vapor deposition. The flexible support layer 110 is selected from PI, Parylene-C, SU-8, or PDMS. Exemplarily, the thickness of the flexible support layer 110 ranges from 5 μm to 1000 μm. Exemplarily, the flexible support layer 110 is cured by heating to form a reliable support, with a selectable temperature range of 135°C to 450°C.

[0129] In some examples, the flexible support layer 110 is made of polyimide (PI). Its precursor solution is spin-coated onto the surface of the release layer 300 at a speed of 500-5000 rpm, and then cured at a temperature below its complete curing temperature (350°C). This differs from the preparation conditions of the auxiliary transfer layer 200; the preferred rotation speed is 4000 rpm. Under these conditions, the thickness of the flexible support layer 110 is 5μm-10μm, resulting in a suitable overall thickness for the skin electrode and good flexibility. Furthermore, the flexible support layer 110, cured at a lower temperature, is less susceptible to dissolution and damage from acetone, N-methylpyrrolidone (NMP), or photoresist developer in subsequent processing steps. It also maintains sufficient surface activity, forming a strong connection with the flexible encapsulation layer 130 in direct contact, which is beneficial for improving the long-term stability of the electrode in vivo.

[0130] S40. The conductive layer 120 is prepared on the flexible support layer 110.

[0131] Specifically, in combination Figure 16 As shown, in some embodiments of this application, the conductive layer 120 includes a plurality of electrode contacts 121, a plurality of electrode pads 122, and a plurality of conductive lines 123. Each conductive line 123 is connected to an electrode pad 122 and an electrode contact 121 at both ends, forming a conductive path. The shapes of the electrode contacts 121, electrode pads 122, and conductive lines 123 have been described in detail above and will not be repeated here.

[0132] In some embodiments of this application, multiple electrode contacts 121, multiple electrode pads 122, and multiple conductive lines 123 can be integrally fabricated and formed simultaneously.

[0133] It should be noted that the materials used to fabricate the electrode contacts 121, electrode pads 122, and conductive lines 123 can be identical or different. Specifically, the materials used to fabricate the electrode contacts 121, electrode pads 122, and conductive lines 123 are each independently selected from one or more of titanium, chromium, silicon carbide, gold, or platinum. The thickness of each material ranges from 5 nm to 500 nm.

[0134] In some embodiments of this application, the deposition methods of electrode contacts 121, electrode pads 122, and multiple conductive lines 123 include one or more of magnetron sputtering, electron beam evaporation, or chemical electroplating.

[0135] In some embodiments of this application, the electrode contacts 121, electrode pads 122, and multiple conductive lines 123 are formed by one or more of the following methods: metal lift-off process, dry etching process, or wet etching process.

[0136] For example, a specific implementation process is as follows: (1) After preparing the flexible support layer 110 and before preparing the conductive layer 120, the surface of the flexible support layer 110 is treated with plasma. (2) One or more thin films of titanium, chromium, silicon carbide, gold or platinum are prepared by magnetron sputtering. (3) Positive photoresist is spin-coated on the surface of the magnetron sputtered thin film, and after exposure and development, the photoresist forms a pattern of the conductive layer 120. (4) The pattern of the conductive layer 120 of the photoresist layer is transferred to the magnetron sputtered film layer by dry etching or wet etching process to form the conductive layer 120. (5) The photoresist is removed.

[0137] Another specific implementation process is as follows: (1) After preparing the flexible support layer 110, spin-coating a negative photoresist onto its surface, exposing and developing it to expose the pattern of the conductive layer 120. (2) Treating the exposed area of ​​the photoresist with plasma. (3) Preparing one or more thin films of titanium, chromium, silicon carbide, gold, or platinum by electron beam evaporation. (4) Removing the photoresist by a lift-off process to form the conductive layer 120.

[0138] It should be noted that, since the plasma treatment process can increase the surface roughness and surface activity of the flexible support layer 110, this step improves the bonding force between the conductive layer 120 (e.g., the metal conductive layer 120) and the flexible support layer 110. Meanwhile, the conductive layer 120 (e.g., the metal conductive layer 120) and the flexible support layer 110 prepared by magnetron sputtering have better bonding force.

[0139] S50 A flexible encapsulation layer 130 is formed on the flexible support layer 110 and the conductive layer 120.

[0140] Specifically, in combination Figure 18 As shown, the flexible encapsulation layer 130 covers the conductive layer 120 and the flexible support layer 110.

[0141] Optionally, in some embodiments of this application, combined with Figure 17 As shown, before fabricating the flexible encapsulation layer 130, the fabrication method further includes fabricating a marking portion 150 on the surface of the flexible support layer 110.

[0142] For example, the marking part 150 is disposed on the flexible support layer 110 and consists of one or more metal blocks of a specific geometry.

[0143] For example, the deposition method of the marking part 150 includes at least one of magnetron sputtering, electron beam evaporation or chemical electroplating.

[0144] For example, the process of forming the marking part 150 is at least one of metal lift-off process, dry etching process or wet etching process.

[0145] For example, a specific implementation process is as follows: (1) After preparing the conductive layer 120, a negative photoresist is spin-coated on its surface, exposed and developed to expose the area where the marking portion 150 is distributed. (2) The exposed area of ​​the photoresist is treated by oxygen plasma or a mixed plasma of oxygen and argon. (3) A thin film of titanium, chromium, or silicon carbide is prepared by electron beam evaporation. (4) A thin film of gold, platinum, or nickel is directly stacked on the metal thin film prepared in step (3) by the same electron beam evaporation process. (5) The photoresist is removed by a lift-off process to form the marking portion 150.

[0146] Optionally, in some embodiments of this application, the step of preparing a flexible encapsulation layer 130 on the flexible support layer 110 and the conductive layer 120 includes covering the flexible support layer 110, the conductive layer 120 and the marking portion 150 with the flexible encapsulation layer 130.

[0147] Specifically, after the marking part 150 is prepared and before the flexible encapsulation layer 130 is prepared, the area on the surface of the flexible support layer 110 that is not covered by the conductive layer 120 and the marking part 150 is treated by oxygen plasma or a mixed plasma of oxygen and argon, so as to improve the bonding force between the flexible support layer 110 and the flexible encapsulation layer 130, avoid delamination, and thus improve the long-term stability after the electrode is implanted in the body.

[0148] Specifically, the flexible encapsulation layer 130 is applied by spin coating, spraying, or chemical vapor deposition. The flexible encapsulation layer 130 is then cured by heating to form a reliable encapsulation, with a selectable temperature range of 135°C to 400°C.

[0149] For example, the flexible encapsulation layer 130 is selected from PI, Parylene-C, SU-8 or PDMS, and its thickness ranges from 5 μm to 1000 μm.

[0150] In some examples, the flexible encapsulation layer 130 is made of polyimide (PI). After its precursor solution is spin-coated onto the surfaces of the flexible support layer 110, the conductive layer 120, and the marking portion 150 at a speed of 500-5000 rpm, it is preferably cured at a temperature above its glass transition temperature (360°C) to form a reliable flexible encapsulation layer 130. Curing at a temperature above the glass transition temperature allows the molecular chains within the PI film to flow, promoting the fusion between the flexible encapsulation layer 130 and the flexible support layer 110, further increasing the bonding force between them. Preferably, the spin-coating speed is 4000 rpm, and the thickness of the flexible encapsulation layer 130 prepared under these conditions is approximately 5 μm, resulting in a suitable overall electrode thickness and good flexibility.

[0151] S60 removes the flexible encapsulation layer 130 from the electrode contacts 121 and electrode pads 122 and prepares the cutout portion.

[0152] In some instances, combined Figure 19 As shown, the overall thickness of the flexible electrode 10 does not exceed 20 μm, and when the etching rate ratio of the materials of the auxiliary transfer layer 200, the flexible support layer 110 and the flexible encapsulation layer 130 to the photoresist in oxygen plasma is close to 1:1 or higher, thick photoresist can be directly used as an etching barrier layer, which reduces the process cost and process complexity.

[0153] The specific implementation process is as follows: (1) A suitable thickness of photoresist is spin-coated on the surface of the flexible encapsulation layer 130 of the electrode, and photolithography is performed in sequence for development, hardening and other steps to form a photoresist pattern. That is, there is no photoresist in the contact area, pad area, hollow area (e.g., the area corresponding to the first hollow part 112 or the second hollow part 221) and the electrode shape outline, while there is photoresist in other areas. (2) By using reactive ion etching process, O2 or O2+CF4 or O2+CF4+Ar mixed gas is introduced to etch the flexible encapsulation layer 130 in the contact area and pad area down to the conductive layer 120, and to etch away the hollow area (e.g., the area corresponding to the first hollow part 112 or the second hollow part 221) and the auxiliary transfer layer 200, flexible support layer 110 and flexible encapsulation layer 130 in the electrode shape outline to form through holes (and release trenches). (3) The photoresist barrier layer is removed by dry or wet method.

[0154] In some instances, when the overall thickness of the flexible electrode 10 exceeds 20 μm, or when the material-to-photoresist ratio of the auxiliary transfer layer 200, flexible support layer 110, and flexible encapsulation layer 130 is much less than 1:1, an additional etching hard mask layer needs to be fabricated. Exemplarily, the etching hard mask material is one of silicon dioxide, silicon nitride, aluminum, or chromium. The etching hard mask is fabricated using a lift-off process or an etching process.

[0155] A specific implementation process is as follows: (1) Deposit one of the following etching hard mask materials on the surface of the electrode flexible packaging layer 130: silicon dioxide, silicon nitride, aluminum, or chromium. (2) Spin-coat photoresist on the surface of the etching hard mask layer, and perform photolithography, development, and hard film steps in one go to form a photoresist pattern, that is, there is no photoresist in the contact area, pad area, area where the cutout is located, and the outline of the electrode shape, while there is photoresist in other areas. (3) Transfer the photoresist pattern to the surface of the etching hard mask material through a wet or dry etching process, and remove the photoresist. (4) By using reactive ion etching, O2, or a mixture of O2 and CF4, or a mixture of O2, CF4 and Ar, is introduced to etch the electrode flexible encapsulation layer 130 in the contact area and pad area down to the conductive layer 120. The cutout area (e.g., the area corresponding to the first cutout portion 112 or the second cutout portion 221) and the auxiliary transfer layer 200, electrode flexible support layer 110 and electrode flexible encapsulation layer 130 in the electrode shape contour are all etched away to form vias (and release trenches). (5) Remove the etched hard mask material layer.

[0156] Another specific implementation process is as follows: (1) Photolithography is performed on the surface of the electrode flexible packaging layer 130 to form a photoresist pattern. Specifically, the photoresist pattern has photoresist in the contact area, pad area, hollow area and electrode shape contour, while there is no photoresist in other areas. (2) Etching hard mask materials such as silicon dioxide, silicon nitride, chromium or aluminum are deposited on the photoresist pattern. (3) A plasma etching hard mask layer is formed by a lift-off process. (4) By a reactive ion etching process, O2, or a mixture of O2 and CF4, or a mixture of O2, CF4 and Ar are introduced to etch the electrode flexible packaging layer 130 in the contact area and pad area down to the conductive layer 120, and to etch away all the hollow areas (e.g., the area corresponding to the first hollow part 112 or the second hollow part 221) and the auxiliary electrode layer, electrode flexible support layer 110 and electrode flexible packaging layer 130 in the electrode shape contour, forming vias (and release trenches). (5) Remove the etched hard mask material layer.

[0157] S70 The flexible support layer 110 separates from the auxiliary transfer layer 200 and is released from the substrate 800.

[0158] Specifically, the flexible support layer 110 and the auxiliary transfer layer 200 are separated by external force or chemical etching process, while the first adhesive portion 111 and the second adhesive portion 210 are kept connected, and the limiting portion 220 is separated from the flexible support layer 110 to obtain the flexible electrode 10.

[0159] Alternatively, the limiting portion 220 can be separated from the flexible support layer 110 by mechanical peeling or chemical etching.

[0160] For example, the release layer 300 may be a single layer, a double-layer metal structure, or a multi-layer metal structure, and both the auxiliary transfer layer 200 and the flexible support layer 110 may be flexible polymer films. It is understood that because the adhesion between flexible polymer materials and different metals varies—for example, metals like gold and platinum are chemically stable and do not undergo chemical reactions on the surface of the flexible polymer material during deposition—the interface between gold or platinum and the flexible polymer film mainly relies on relatively weak van der Waals forces. This allows the area of ​​the auxiliary transfer layer 200 covered by the release layer 300 to be easily peeled from the flexible support layer 110, and it is often used as the metal bonding layer in the release layer 300 described above.

[0161] For example, metals such as chromium and titanium are chemically reactive. When used as materials for the preparation of the release layer 300, they can react chemically with oxygen, nitrogen and other atoms on the molecular chains of flexible polymer materials during deposition to form stable metal-oxygen / nitrogen-carbon covalent bonds. These chemical bonds are like welding at the interface, with strong bonding force. They are often used as metal adhesion layers in the release layer 300 described above.

[0162] In some examples, the auxiliary transfer layer 200, flexible support layer 110, and flexible encapsulation layer 130 are all made of PI, and the metal release layer 300 is made of a titanium / gold composite film (the titanium layer is the metal adhesion layer, and the gold layer is the metal bonding layer). By applying external force (e.g., mechanical peeling, prying open with tweezers) and pulling the tearing part 140, the flexible support layer 110 and the release layer 300 are separated at the gold layer, thus achieving separation of the flexible support layer 110 from the auxiliary transfer layer 200 in a predetermined area; while in the area not covered by the release layer 300, the flexible support layer 110 and the auxiliary transfer layer 200 are firmly connected.

[0163] In other specific examples, the auxiliary transport layer 200, the flexible support layer 110, and the flexible encapsulation layer 130 are all made of PDMS, and the release layer 300 is a single-layer metal structure made of a nickel thin film. The flexible support layer 110 and the auxiliary transport layer 200 are separated by a chemical etching process. Specifically, the prepared sample is immersed in a nickel etching solution for a period of time to at least partially remove the release layer 300, thereby separating the flexible support layer 110 from the auxiliary transport layer 200. In the area not covered by the release layer 300, the flexible support layer 110 and the auxiliary transport layer 200 are firmly connected.

[0164] Optionally, after separating the flexible support layer 110 and the auxiliary transfer layer 200 into a predetermined area, the flexible electrode 10 can be pried open by mechanical peeling (e.g., with tweezers) and the flexible electrode 10 can be released from the substrate 800 by pulling and tearing the tearing part 140.

[0165] The technical solutions provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope, and the technical features of different embodiments can be freely combined. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A flexible electrode for brain-computer interfaces, characterized in that, The flexible electrode includes an electrode body layer, an auxiliary transfer layer, and a release layer. The electrode body layer and the auxiliary transfer layer are at least partially connected to form a force-bearing part of an external driving member. The release layer is disposed between the electrode body layer and the auxiliary transfer layer to separate a predetermined area of ​​the electrode body layer and the auxiliary transfer layer, forming a gap.

2. The flexible electrode for brain-computer interface as described in claim 1, characterized in that, The electrode body layer includes a flexible support layer, the flexible support layer includes a first adhesive portion and a contact area, the first adhesive portion is disposed close to the contact area, and the auxiliary transmission layer includes a second adhesive portion, the second adhesive portion is connected to the first adhesive portion, so that the electrode body layer and the auxiliary transmission layer form the force-bearing portion at the connection point.

3. The flexible electrode for brain-computer interface as described in claim 2, characterized in that, The flexible support layer and the auxiliary transmission layer are spaced apart from the force-bearing part. And / or, the electrode body layer and the auxiliary delivery layer may form a "V" shape during implantation and delivery.

4. The flexible electrode for brain-computer interface as described in claim 3, characterized in that, The auxiliary transfer layer further includes a limiting part, which is integral with the second adhesive part, and at least a portion of the limiting part and at least a portion of the flexible support layer form a pocket structure. And / or, the first adhesive portion and the second adhesive portion are an integral structure; And / or, the material of the first adhesive portion is an organic polymer; And / or, the material of the second adhesive portion is an organic polymer; And / or, the first adhesive portion and the second adhesive portion are made of the same material.

5. The flexible electrode for brain-computer interface as described in claim 1, characterized in that, The peeling layer is disposed on the flexible support layer and at least partially fills the area between the flexible support layer and the auxiliary transfer layer. And / or, the peeling layer is located on the auxiliary transfer layer and at least partially fills the area spaced between the auxiliary transfer layer and the flexible support layer.

6. The flexible electrode for brain-computer interface as described in claim 5, characterized in that, The peeling layer is a single-layer metal structure to achieve separation of a predetermined area between the flexible support layer and the auxiliary transfer layer; Alternatively, the release layer is a double-layer metal structure, including a metal adhesion layer and a metal bonding layer, wherein the metal adhesion layer is strongly adhered to the flexible support layer or the auxiliary transfer layer, and the metal adhesion layer and the metal bonding layer are made of different metal materials; Alternatively, the peeling layer may be a multi-layered metal structure to achieve separation of a predetermined area between the flexible support layer and the auxiliary transfer layer.

7. The flexible electrode for brain-computer interface as described in claim 2, characterized in that, The electrode body layer includes the flexible support layer, the conductive layer, and the flexible encapsulation layer arranged sequentially; the electrode body layer also includes a tearing portion, which is used to separate at least partially the portion of the electrode body layer and the auxiliary transfer layer, excluding the first adhesive portion and the second adhesive portion, under the action of external force; The tear-off portion is disposed on the flexible support layer and / or the flexible encapsulation layer; And / or, the tear-off portion is disposed at the edge of the flexible support layer and / or the tear-off portion is disposed at the edge of the flexible encapsulation layer.

8. The flexible electrode for brain-computer interface as described in claim 3, characterized in that, The flexible electrode also includes a marking portion, which is disposed on the flexible support layer and distributed around the contact area or the electrode contact. The marking portion is used to locate the real-time position of the electrode contact in the body when the electrode contact is implanted.

9. The flexible electrode for brain-computer interface as described in claim 4, characterized in that, The flexible electrode also includes a hollow portion, which includes a plurality of first hollow portions and a plurality of second hollow portions. The first hollow portions are disposed in the contact area, corresponding to the electrode body layer, and are offset from the electrode contact. The second hollow portions are disposed on the limiting portion, and the orthographic projection of the second hollow portion on the flexible support layer at least partially overlaps with the first hollow portion.

10. A method for fabricating a flexible electrode for a brain-computer interface, characterized in that, The preparation method includes the following steps: An auxiliary transfer layer is provided, the auxiliary transfer layer including a second adhesive portion and a limiting portion connected to the second adhesive portion; A release layer is prepared on the auxiliary transfer layer, the release layer covering at least a portion of the limiting portion; A flexible support layer is prepared in situ on the release layer, the flexible support layer covers the second adhesive portion and the release layer, and the portion of the flexible support layer corresponding to the second adhesive portion is the first adhesive portion; The conductive layer is fabricated on the flexible support layer, and the conductive layer includes a plurality of electrode contacts and a plurality of electrode pads; A flexible encapsulation layer is formed on the flexible support layer and the conductive layer, the flexible encapsulation layer covering the conductive layer and the flexible support layer; Remove the flexible encapsulation layer from the electrode contacts and electrode pads, and prepare the cutout portion; The flexible support layer is separated from the auxiliary transfer layer, while the first adhesive portion and the second adhesive portion remain connected. The limiting portion is then separated from the flexible support layer to obtain the flexible electrode.

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