Electrode assembly and method of manufacturing the same

Abstract

This application provides an electrode assembly and a method for manufacturing the same. The electrode assembly includes a flexible electrode and a variable-hardness coating. The flexible electrode includes a flexible substrate and electrode points protruding from the upper surface of the flexible substrate. The variable-hardness coating includes a first coating and a second coating. The first coating at least partially covers the outer surface of the flexible electrode and has windows for exposing the electrode points. The second coating at least fills the windows to cover the electrode points. When the flexible electrode is located outside the body of a subject, it has a first hardness greater than that of the flexible substrate. During implantation, the outer portion of the first coating is wetted by the subject's bodily fluids. After locating the target tissue, the inner portion of the first coating is wetted by the subject's bodily fluids. The electrode assembly of this application can improve the implantation compliance of the flexible electrode and reduce damage to brain tissue during implantation.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to an electrode assembly and its preparation method. Background Technology

[0002] Flexible electrodes are too soft to provide sufficient axial support for tissue insertion. Currently, the common solution is to pre-drill a needle hole at the electrode tip and insert a guide pin as temporary rigid support. The guide pin is then removed after the electrode is implanted into the tissue.

[0003] However, the application of guide pins introduces a series of adverse consequences. For example, the assembly connection between the guide pin and the electrode tip can create a local abrupt change in cross-section, increasing resistance during electrode implantation. Furthermore, during guide pin removal, the friction between the guide pin and the electrode may cause electrode displacement, leading to electrode misalignment. Moreover, the combined structure of the flexible electrode and guide pin is fragile and easily bent or broken due to external forces during packaging, transportation, and preoperative procedures.

[0004] Those skilled in the art have attempted to achieve controllable hardness of flexible electrodes through various means in order to reduce reliance on guide pins. For example, known embodiments, such as US10335089B1, CN111450411A, CA1191064A, and US11583233B2, form a high-hardness coating on the outer surface of the flexible electrode to protect it and provide the axial rigidity required for implantation. After implantation, the coating absorbs water and dissolves or softens, restoring the electrode's flexibility.

[0005] However, it is worth noting that these known embodiments do not address the issue of electrode wrapping and release, which makes it difficult to ensure implant compliance when using the variable stiffness design for flexible electrodes in the above-mentioned known embodiments.

[0006] Specifically, for functional purposes, electrode points typically protrude from the flexible substrate. If only a softening coating is applied to the outer surface of the flexible electrode, the coating cannot completely encapsulate the electrode points. Therefore, during implantation, exposed electrode points can negatively impact the process, leading to problems such as entrapment and tissue damage. Conversely, if only a dissolving coating is applied to the outer surface of the flexible electrode, the coating can encapsulate the electrode points. However, there is a possibility that the coating may completely dissolve before the electrode is properly implanted. In this case, the electrode points are exposed, resulting in the same adverse consequences as described above. Summary of the Invention

[0007] In view of this, this application provides an electrode assembly and a method for manufacturing the same, which is mainly used to solve the problem that protruding electrode points adversely affect electrode implantation, so that the electrode can be implanted smoothly and efficiently, and the electrode points can be exposed as desired after implantation.

[0008] The electrode assembly includes a flexible electrode and a variable hardness coating. The flexible electrode includes a flexible substrate and electrode points protruding from the upper surface of the flexible substrate. The variable hardness coating includes a first coating and a second coating. The first coating at least partially covers the outer surface of the flexible electrode and has windows for exposing the electrode points. The second coating at least fills the windows to cover the outer surface of the electrode points.

[0009] When the flexible electrode is located outside the subject's body, the first coating is in a first morphology, possessing a first hardness uniform along its thickness direction. This first hardness is greater than the hardness of the flexible substrate, serving to provide protection for the flexible electrode. The outer surface of the second coating is not lower than the outer surface of the electrode point.

[0010] During the implantation of the flexible electrode into the target tissue within the subject's body, the first coating is in a second state. Its outer portion has a second hardness, lower than the first hardness or comparable to the hardness of the flexible substrate, to reduce implantation friction. The inner portion has a third hardness comparable to the first hardness, to maintain the axial force of the implanted flexible electrode. The second coating gradually dissolves and thins, gradually exposing the electrode points within the window. The second state is obtained by immersing the outer portion of the first coating in the first state with the subject's bodily fluids.

[0011] After the flexible electrode is positioned in the target tissue within the subject's body, the first coating is in a third state, possessing a fourth hardness uniform along its thickness direction. This fourth hardness is comparable to the second hardness and is used to restore the flexible electrode to its original flexibility. The second coating is completely dissolved, maximizing the exposure of the electrode points within the window. The third state is achieved by wetting the inner portion of the first coating in the second state with the subject's bodily fluids.

[0012] Optionally, the second coating is circumferentially continuous, covering the outer surface of the first coating and the outer surface of the electrode points.

[0013] Optionally, the ratio of the depth of the window to the thickness of the portion of the second coating covering the outer surface of the first coating is between 4:1 and 4.2:1.

[0014] Optionally, the second coating is circumferentially discontinuous and only fills the window.

[0015] Optionally, the outer surface of the second coating is not lower than the outer surface of the first coating.

[0016] Optionally, the width of the window can be greater than the width of the electrode point.

[0017] Optionally, the electrode assembly also includes a guide pin, the lower surface of which is attached to the outer wall of the guide pin, and the first coating and the flexible electrode together wrap the outer wall of the guide pin; the upper surface of the flexible substrate is provided with a groove, and the first coating fills the groove.

[0018] Optionally, there are multiple grooves, which are spaced apart along the width direction of the flexible substrate; wherein, the multiple grooves are symmetrically arranged along the central axis of the flexible substrate, but in any two adjacent grooves, the groove width of the groove closer to the central axis is greater than the groove width of the groove farther away from the center of the flexible substrate.

[0019] Optionally, the distance between two adjacent grooves near the central axis is smaller than the distance between two adjacent grooves far from the central axis.

[0020] Optionally, the outer wall of the guide pin has a protrusion located at the distal end of the electrode point, the protrusion being axially aligned with the electrode point.

[0021] Optionally, the protrusion is an axially extending ridge, at least its proximal end being a slope; or, the protrusion comprises a plurality of axially spaced protrusions, each protrusion having a rounded outer surface.

[0022] Optionally, the protrusion has at least a first segment whose height gradually increases from near to far.

[0023] Optionally, the protrusion may also have a second segment whose height gradually decreases from near to far, the second segment being located at the far end of the first segment.

[0024] This application also provides a method for manufacturing an electrode assembly, comprising forming the aforementioned first coating and second coating on a flexible electrode, respectively.

[0025] Optionally, the step of forming the first coating includes: attaching a flexible electrode to a guide pin; placing the flexible electrode and the guide pin horizontally with the groove on the upper surface of the flexible substrate facing upward; dripping an aqueous solution of the first coating into the groove from above; and performing a curing operation on the aqueous solution of the first coating.

[0026] Optionally, after performing the curing operation on the first coating aqueous solution, the method further includes: rotating the flexible electrode and the guide needle, dripping the first coating aqueous solution onto the outer surface of other parts of the flexible electrode and the guide needle from above, until the first coating aqueous solution completely covers the outer surface of the flexible electrode and the guide needle; and performing the curing operation again.

[0027] Optionally, after performing a curing operation on the first coating aqueous solution, the method further includes: immersing the flexible electrode and the guide needle in the first coating aqueous solution; removing the flexible electrode and the guide needle; and performing a curing operation on the first coating aqueous solution on the surfaces of the flexible electrode and the guide needle.

[0028] Optionally, before forming the second coating, the method further includes: removing the first coating at the location of the corresponding electrode point to form a window for exposing the electrode point; the step of forming the second coating includes: immersing the flexible electrode and guide needle, which are wrapped by the first coating, in an aqueous solution of the second coating; removing the flexible electrode and guide needle; and performing a curing operation on the aqueous solution of the second coating that adheres to the surface of the first coating and fills the window.

[0029] Optionally, the step of forming the first coating includes: attaching a flexible electrode to a guide pin; horizontally immersing the flexible electrode and the guide pin in an aqueous solution of the first coating, with the groove on the upper surface of the flexible substrate facing upward; removing the flexible electrode and the guide pin; and performing a curing operation on the aqueous solution of the first coating on the surfaces of the flexible electrode and the guide pin.

[0030] Optionally, the step of fabricating the flexible electrode includes: forming a flexible substrate on a rigid substrate, with a first sacrificial layer disposed between the lower surface of the flexible substrate and the upper surface of the rigid substrate. Before the step of forming the first coating, the method further includes: depositing a second sacrificial layer on the upper surface of the flexible substrate, completely covering the electrode points and the upper surface of the flexible substrate; selectively removing a portion of the second sacrificial layer, retaining only the portion covering the electrode points; removing the first sacrificial layer and peeling off the rigid substrate; in the step of forming the first coating, the first coating encapsulates the second sacrificial layer; before the step of forming the second coating, removing the second sacrificial layer to form a window for exposing the electrode points.

[0031] Optionally, the extensibility of the second sacrificial layer is greater than that of the first sacrificial layer.

[0032] Optionally, the step of forming the second coating includes: filling the window with the material of the second coating, wherein the amount of the material of the second coating is configured such that the outer surface of the second coating formed after its curing is not lower than the outer surface of the first coating.

[0033] The electrode assembly of this application can improve the implantation compliance of flexible electrodes and reduce damage to brain tissue during implantation. Attached Figure Description

[0034] Figure 1 This is a cross-sectional view of the electrode assembly according to an embodiment of this application;

[0035] Figure 2 yes Figure 1 A cross-sectional view of the first embodiment of the middle electrode assembly along the AA direction;

[0036] Figure 2A yes Figure 2 A magnified view of a section at point B in the middle;

[0037] Figure 3 yes Figure 1A cross-sectional view of the middle electrode assembly along the AA direction in a second embodiment;

[0038] Figure 3A yes Figure 3 A magnified view of a section at point C;

[0039] Figures 4-10 This is a schematic diagram of the process of manufacturing the electrode assembly according to the first embodiment of this application;

[0040] Figures 11-17 This is a schematic diagram of the process of manufacturing the electrode assembly according to the second embodiment of this application. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the accompanying drawings.

[0042] like Figures 1 to 3A As shown, the electrode assembly 100 includes a flexible electrode 1 and a variable hardness coating 2. The flexible electrode 1 includes a flexible substrate 11 and electrode points 12 protruding from the upper surface of the flexible substrate 11. The flexible substrate 11 is typically made of a flexible polymer material with good biocompatibility, such as polyimide or phenelzine-C. The electrode points 12 are patterned on the flexible substrate 11 using a micro-nano fabrication process to form a pattern of a conductive metallic material. The electrode points 12 protrude from the upper surface of the flexible substrate 11 to facilitate good electrical contact with nerve tissue.

[0043] The variable hardness coating 2 includes a first coating 21 and a second coating 22. The first coating 21 at least partially covers the outer surface of the flexible electrode 1 and has a window 211 for exposing the electrode point 12. The window 211 refers to an opening or notch area formed in the first coating 21 corresponding to the position of the electrode point 12. The second coating 22 at least fills the window 211 to cover the outer surface of the electrode point 12.

[0044] When the flexible electrode 1 is located outside the subject's body, the first coating 21 is in a first state, possessing a first hardness that is uniform along its thickness direction. This first hardness is greater than the hardness of the flexible substrate 11, providing protection for the flexible electrode 1. The outer surface of the second coating 22 is not lower than the outer surface of the electrode point 12. The first state refers to the condition of the first coating 21 when the flexible electrode 1 is located outside the subject's body. "Uniform" means that the hardness difference between layers along the thickness direction is within a preset range, such as 2%. Similarly, "equivalent" in the following text is interpreted in the same way, meaning that the two hardness differences are within, for example, a preset range of 2%.

[0045] During the implantation of the flexible electrode 1 into the target tissue within the subject's body, the first coating 21 is in a second state. At this time, the outer portion of the first coating 21 has a second hardness, lower than the first hardness or comparable to the hardness of the flexible substrate 11, to reduce the implantation friction of the flexible electrode 1. The inner portion of the first coating 21 has a third hardness comparable to the first hardness, to maintain the implantation axial force of the flexible electrode 1. The second coating 22 gradually dissolves and thins, and the electrode point 12 gradually emerges in the window 211. The second state is obtained after the outer portion of the first coating 21 in the first state is soaked in the subject's bodily fluids, which is also the state of the first coating 21 during the implantation of the flexible electrode 1 into the target tissue within the subject's body. At this time, the hardness of the outer portion of the first coating 21 decreases to the second hardness after being soaked in the subject's bodily fluids. The outer portion refers to the area of ​​the first coating 21 near the bodily fluid contact surface, and the inner portion refers to the area of ​​the first coating 21 near the flexible substrate 11.

[0046] After the flexible electrode 1 is positioned in the target tissue within the subject's body, the first coating 21 is in its third state. At this time, the first coating 21 has a fourth hardness that is uniform along its thickness direction. This fourth hardness is comparable to the second hardness and is used to restore the flexible electrode 1 to its original flexibility. The second coating 22 is completely dissolved, and the electrode point 12 is maximally exposed in the window 211. The third state is obtained by configuring the inner portion of the first coating 21 in the second state to be wetted by the subject's bodily fluids; this is also the state exhibited by the first coating 21 after the flexible electrode 1 is successfully positioned in the target tissue within the subject's body. At this time, the inner portion of the first coating 21 is also fully wetted by bodily fluids, exhibiting a uniform fourth hardness overall. The electrode point 12 is maximally exposed because the second coating 22 that originally covered it is completely dissolved. Therefore, the absence of the second coating 22 covering the electrode point 12 is defined as maximally exposed.

[0047] By setting the variable hardness coating 2 as a double-layer structure including a first coating 21 and a second coating 22, and making the first coating 21 present three forms at different stages, the hardness change of the flexible electrode 1 is realized throughout the entire process from external protection to implantation, taking into account both low friction compliance and rigid support, and then to in vivo flexible recovery.

[0048] During the in vitro phase, the first coating 21 is in a first state where it has not absorbed water or solidified. Its uniform and relatively high first hardness along its thickness direction provides protection for the flexible electrode 1, making it less prone to bending or damage due to external forces during packaging, transportation, and preoperative procedures. Simultaneously, the second coating 22 fills the window 211 and encloses the electrode point 12, preventing the electrode point 12 from being contaminated or mechanically damaged due to exposure. The outer surface of the second coating 22 is not lower than the outer surface of the electrode point 12, which helps to form a relatively smooth and continuous outer contour, reducing abrupt changes and sharp edges on the outer surface, and thus minimizing tissue damage during subsequent implantation.

[0049] During implantation, the first coating 21 partially absorbs water and transforms into its second form, with its outer portion softening to a second hardness due to being wetted by bodily fluids. The reduced or uniform hardness difference between the softened outer portion and the brain tissue decreases friction between them, thereby reducing tissue damage during implantation. Simultaneously, the softened outer portion possesses self-lubricating properties, facilitating smooth advancement of the flexible electrode 1 within the tissue and improving implantation compliance. Meanwhile, the inner portion maintains a higher third hardness, continuing to provide axial rigid support for the flexible electrode 1, ensuring sufficient axial force for it to penetrate the pia mater and reach the target tissue. Therefore, this "soft inside hard" hardness gradient distribution of the first coating 21 in this form simultaneously addresses the dual requirements of reducing friction and maintaining the necessary axial stiffness for implantation, thereby improving the implantation efficiency of the flexible electrode and reducing tissue damage during implantation.

[0050] Although the second coating 22 gradually dissolves and thins during this stage, gradually exposing the electrode point 12 in the window 211, the second coating 22 still maintains at least partial coverage of the electrode point 12. This can at least partially eliminate the obstruction caused by the protrusion of the electrode point 12, preventing the fully protruding electrode point 12 from damaging tissue during implantation. Furthermore, because the dissolution of the second coating 22 is gradual (only the outer portion of the second coating 22 dissolves, exposing the electrode point 12), even if the electrode point 12 begins to be partially exposed before implantation is complete, the degree of exposure is limited. Therefore, the adverse effects of partially exposed electrode points 12 on the implantation process are acceptable.

[0051] After positioning, the first coating 21 completely absorbs water and transforms into its third form, with its overall hardness decreasing to a fourth hardness comparable to the flexible substrate 11. The flexible electrode 1 returns to its original flexibility, allowing it to deform in sync with the micro-movements of the brain tissue, avoiding immune rejection and glial scarring caused by mechanical mismatch after long-term implantation. Simultaneously, the second coating 22 is completely dissolved, maximizing the exposure of the electrode point 12 within the window 211 to establish a sufficient electrical contact interface with the target neural tissue, thereby improving the diagnostic and / or therapeutic effects of the electrode.

[0052] Therefore, the transformation of the three forms of the first coating 21 is driven by the gradual infiltration of body fluids from the outside in, without the need for external energy input or additional manipulation steps. Furthermore, by configuring the thickness and / or material selection of the second coating 22, the clinical implantation time can be matched, enabling the first coating 21 to initiate softening at the desired time (described later), demonstrating good operability and usability.

[0053] The material of the first coating 21 includes a UV-curable adhesive. A UV-curable adhesive is a polymeric material or its prepolymer solution that can undergo a cross-linking and curing reaction under irradiation with a light source of a specific wavelength, including at least one of polyurethane (PU), polyacrylamide (PAAm), and polyacrylic acid (PAA).

[0054] The first coating 21 uses a light-curing adhesive, and its curing process can be precisely controlled by light. Light curing technology features fast curing speed and high control precision, enabling curing and shaping to be completed quickly after application, thus improving the uniformity of the first coating 21's thickness. Simultaneously, the aforementioned light-curing adhesive materials are all hydrophilic; upon contact with the subject's bodily fluids, they absorb water and swell, gradually decreasing in hardness and achieving self-lubrication. Since the bodily fluids gradually penetrate from the outer surface to the inner surface, the softening of the first coating 21 also follows a gradient pattern from the outside in. The outer portion softens first, while the inner portion softens later, naturally forming the "soft outside, hard inside" hardness distribution required during implantation.

[0055] like Figure 2 and Figure 2A As shown, in one embodiment, the second coating 22 is circumferentially continuous, covering the outer surface of the first coating 21 and the outer surface of the electrode point 12. The second coating 22 being circumferentially continuous means that it forms an uninterrupted, continuous covering layer along the circumference of the flexible electrode 1. The second coating 22 not only fills the window 211 to cover the outer surface of the electrode point 12, but also covers the outer surface of the first coating 21. This allows the second coating 22 to cover the entire outer surface of the electrode assembly 100, meaning the outermost surface of the electrode assembly 100 is entirely composed of the second coating 22.

[0056] The second coating 22 is circumferentially continuous and completely encapsulates the first coating 21, further enhancing the integrity of the outer surface of the electrode assembly 100 during in vitro operation. This reduces material interfaces and structural abrupt changes on the outer surface, providing more comprehensive protection during transportation and storage. Simultaneously, the continuous coverage formed by the second coating 22 on the outermost layer of the electrode assembly 100 eliminates surface discontinuities caused by the material interface between the first coating 21 and the second coating 22, resulting in a smoother outer contour of the electrode assembly 100, improving implantation compliance and reducing tissue damage during implantation.

[0057] It is worth noting that the presence of the second coating 22 prevents direct contact between bodily fluids and the first coating 21. The softening and lubrication process of the first coating 21 can only begin after the second coating 22 has dissolved. Therefore, if the second coating 22 is too thick, its dissolution will take too long, potentially causing the first coating 21 to remain unexposed during the implantation process. This would result in the flexible electrode 1 being in a state of high friction with the tissue throughout the implantation process, hindering smooth implantation. Conversely, if the second coating 22 is too thin, it may dissolve too quickly, causing the electrode point 12 to be exposed prematurely, which would increase the risk of tissue damage during implantation.

[0058] Therefore, the thickness of the second coating 22, particularly the thickness of the portion enclosing the first coating 21 (hereinafter referred to as the "enclosing coating portion"), is preferably configured to be completely dissolved before the implantation process reaches 50% (e.g., 20%). In this way, the second coating 22 can enter the softening and lubrication stage as early as possible, improving implantation compliance and maintaining the state of enclosing the electrode point 12.

[0059] By configuring the ratio of the depth of window 211 to the thickness of the encapsulating coating portion, it can be ensured that the encapsulating coating portion is completely dissolved when the implantation process reaches a desired stage. For example, if it is desired that the encapsulating coating portion is completely dissolved when the implantation process reaches 20%, then ideally, the first coating 21 filled in window 211 (hereinafter referred to as the "window filling portion") will be completely dissolved exactly during the remaining 80% of the implantation process. Alternatively, it is also feasible that the time required for the window filling portion to completely dissolve is slightly longer than the time required for the remaining 80% of the implantation process. Based on this, the ratio between the depth of window 211 and the thickness of the encapsulating coating portion is approximately 4:1 or slightly greater than 4:1 (e.g., 4.1 to 4.2:1).

[0060] The specific thickness of the coating can be determined based on the clinical implantation time of the electrode and the coating's dissolution rate. Generally, the clinical implantation time varies depending on the type of electrode. For example, electrodes used in stereotactic electroencephalography (SEEG) can be implanted in a few minutes (e.g., 6-8 minutes). Similarly, the coating's dissolution rate varies depending on the specific material.

[0061] In this embodiment, the second coating 22 may be made of any suitable material, including but not limited to the materials provided by CN106029161A or CN111450411A, sugars such as sucrose or trehalose, biodegradable synthetic polymers such as polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyethylene glycol (PEG), and bioactive molecular coatings with therapeutic effects, i.e., drug coatings such as dexamethasone and heparin.

[0062] Based on the electrode implantation time and the expected percentage of the total implantation time when the second coating 22 completely dissolves (e.g., 20%, approximately 3 minutes), the coating thickness can be roughly determined using a diffusion model (dissolution time ≈ coating thickness^2 / diffusion coefficient), assuming the second coating 22 is selected (and the diffusion coefficient is known). For example, when sucrose is used as the material for the second coating 22, the thickness of the coating portion is approximately 50-100 µm when it completely dissolves in the expected 3 minutes, while a PVP coating typically requires 10-50 µm. With the coating portion determined, the depth of the window 211, i.e., the thickness of the window filling portion, can be determined based on the aforementioned expected ratio.

[0063] Using the above method, the thickness of the coating portion can be controlled within an appropriate range, allowing the flexible electrode 1 to completely dissolve at the desired implantation level, and enabling the first coating 21 to come into contact with body fluid and begin the softening process at the desired time point. In this way, while achieving lubrication and resistance reduction on the outer surface, the axial support stiffness required for implantation is maintained, and premature exposure of the electrode point 12 is avoided.

[0064] like Figure 3 and Figure 3A As shown, in another embodiment, the second coating 22 is circumferentially discontinuous, filling only the window 211 without covering the outer surface of the first coating 21. This means that when the flexible electrode 1 is implanted, the outer portion of the first coating 21 is in direct contact with the body fluid, allowing it to be more quickly wetted and softened, thus achieving lubrication of the outer surface in a shorter time. This enables the flexible electrode 1 to achieve surface lubricity in the initial implantation stage, improving implantation compliance.

[0065] Since the softening of the first coating 21 is not constrained by the dissolution rate of the second coating 22, the timing control of the entire hardness transition process is more direct and predictable. Simultaneously, the second coating 22 in window 211 continues to protect and encapsulate the electrode point 12, gradually dissolving as the implantation process progresses, and the electrode point 12 is gradually exposed within window 211. During this process, the outer surface of the first coating 21 softens and provides lubrication. Even if the electrode point 12 is partially exposed due to the gradual dissolution of the second coating 22, the exposure of the electrode point 12 is gradual, and a soft, lubricated surface has been formed on the outer surface of the first coating 21, which can still significantly reduce friction between the flexible electrode 1 and the tissue.

[0066] Furthermore, since the second coating 22 only fills the window area, the amount of second coating 22 used can be reduced, resulting in cost savings. This will simultaneously reduce the particles released by the second coating 22 due to dissolution, reducing potential adverse effects on the tissue.

[0067] Please continue reading. Figure 3A The outer surface of the second coating 22 is not lower than the outer surface of the first coating 21, including the outer surface of the second coating 22 being flush with or higher than the outer surface of the first coating 21.

[0068] Understandably, if the outer surface of the second coating 22 is lower than the outer surface of the first coating 21, a depression will form in the window 211 region. This depression may cause tissue embedding and generate resistance during the implantation of the flexible electrode 1, and the depression may also damage brain tissue. By ensuring that the outer surface of the second coating 22 is not lower than the outer surface of the first coating 21, a smooth transition or slight bulge is formed between the outer surface of the window 211 region and the outer surface of the first coating 21, the problems of tissue embedding and increased resistance caused by the depression are avoided.

[0069] When the outer surface of the second coating 22 is flush with the outer surface of the first coating 21, the overall outer contour of the electrode assembly 100 presents a continuous and flat shape, which is conducive to forming uniform contact with the tissue during implantation, eliminating the surface discontinuity caused by height difference in the window 211 area, keeping the outer contour of the electrode assembly 100 smooth at the window 211, reducing tissue damage during implantation, and improving implantation compliance.

[0070] like Figure 2A and Figure 3A As shown, the width of window 211 is greater than the width of electrode point 12. Width refers to the dimension in the direction perpendicular to the length of the flexible electrode 1 (i.e., the implantation direction) and parallel to the surface of the flexible substrate 11, corresponding to... Figure 2 and Figure 3 The middle dimension is the circumferential dimension, corresponding to... Figures 4-5 , Figures 11-13 The sum represents the dimensions in the left and right horizontal directions.

[0071] Window 211 is essentially a notch in the first coating 21, designed to expose the electrode point 12 after implantation, enabling stimulation of brain neurons or acquisition of electrical signals. Window 211 has a wider width than the electrode point 12. Even when the second coating 22 is completely dissolved, maximizing the exposure of the electrode point 12, there is still space between the edge of the electrode point 12 and the edge of window 211, preventing it from being pressed against the edge of window 211. This avoids occlusion caused by contact between the electrode point 12 and the edge of window 211, improving the quality of stimulation or signal acquisition.

[0072] Furthermore, the wider window 211 creates a gap between its edge and the edge of the electrode point 12, allowing the material of the second coating 22 to fill the gap. The second coating 22 not only covers the upper surface of the electrode point 12 but also extends to its sides and fills the gap between the electrode point 12 and the edge of the window 211, thus providing complete coverage of the electrode point 12 and enhancing its protective effect.

[0073] like Figure 1 , Figure 2 and Figure 3 As shown, the electrode assembly 100 also includes a guide pin 3. The lower surface of the flexible electrode 1, i.e., the side of the flexible substrate 11 facing away from the electrode point 12, is attached to the outer wall of the guide pin 3. The first coating 21 and the flexible electrode 1 together wrap the outer wall of the guide pin 3, so that the guide pin 3, the flexible electrode 1, and the first coating 21 form an integrated structure. The upper surface of the flexible substrate 11 is provided with a groove 111, and the first coating 21 fills the groove 111.

[0074] The guide pin 3 has high rigidity and a sharp tip, and is made of metal materials with high hardness and biocompatibility such as tungsten and stainless steel. It is used to provide axial support during the implantation of the flexible electrode 1 and can be removed after the flexible electrode 1 is implanted. The cross-sectional shape of the groove 111 can be rectangular, triangular, trapezoidal or arc-shaped, etc., and this application does not limit it.

[0075] The grooves 111 on the upper surface of the flexible substrate 11 provide additional space for the first coating 21, allowing the upper surface of the flexible substrate 11 to hold more of the first coating 21 material. After the flexible electrode 1 is implanted into the subject and comes into contact with bodily fluids, the first coating 21 filled in the grooves 111 is embedded inside the flexible substrate 11, requiring the bodily fluids to travel a longer penetration path to reach the depths of the grooves 111. Therefore, the softening rate of the first coating 21 in the grooves 111 is slower than that of the first coating 21 on the outer surface, thereby prolonging the time that the first coating 21 maintains high hardness. This allows the flexible electrode 1 to continuously provide axial support during implantation, which is particularly beneficial in clinical scenarios where deeper target implantation requires a longer implantation distance.

[0076] On the other hand, the groove 111 alters the stress state between the upper and lower surfaces of the flexible substrate 11. Since the groove 111 is located on the upper surface of the flexible substrate 11, while the lower surface of the flexible substrate 11 is a continuous, complete plane, the first coating 21 expands in volume when it fills the groove 111 and undergoes a curing process. The internal stress generated by this expansion acts on the inner wall of the groove 111, causing the upper surface of the flexible substrate 11 to be compressed along its width, while the lower surface, lacking the groove 111 and the first coating 21, retains its original stress state. This asymmetrical stress between the upper and lower surfaces drives the flexible substrate 11 to bend towards the lower surface without the groove 111, transforming the originally flat flexible substrate 11 into a downwardly curved arc profile. When the bent flexible substrate 11 is assembled with the guide pin 3, the lower surface of the flexible substrate 11 can better fit and wrap around the arc-shaped outer wall of the guide pin 3, creating a tight adhesion between the flexible substrate 11 and the guide pin 3, preventing air gaps between them, and thus improving product yield. Based on this, the first coating 21 formed subsequently can continuously wrap around the outer contour of the flexible substrate 11 that has been well attached to the guide pin 3, while covering the outer surfaces of the flexible substrate 11 and the guide pin 3, so as to prevent the first coating 21 from entering between the flexible substrate 11 and the guide pin 3.

[0077] like Figure 4 , Figure 5 , Figures 11-13 As shown, there are multiple grooves 111, which are spaced apart along the width direction of the flexible substrate 11. The grooves 111 are symmetrically arranged along the central axis 112 of the flexible substrate 11, but in any two adjacent grooves 111, the groove width of the groove closer to the central axis 112 is greater than the groove width of the groove farther from the central axis 112. The central axis 112 is a virtual line extending along the length direction of the flexible substrate 11 and equally bisecting the width of the flexible substrate 11. The groove width refers to the opening size of the groove 111 in the width direction of the flexible substrate 11.

[0078] The symmetrically distributed grooves 111 ensure that the stress generated by the curing and expansion of the first coating 21 is also symmetrical along the width of the flexible substrate 11, thereby driving the flexible substrate 11 to form a symmetrical bending deformation along the width direction. If the distribution of the grooves 111 is asymmetrical, the stress generated by the curing and expansion of the first coating 21 will be biased to one side, causing the flexible substrate 11 to bend or twist at an angle, which is not conducive to the uniform adhesion between the flexible substrate 11 and the cylindrical outer wall of the guide pin 3. The symmetrically distributed grooves 111 make the bending deformation of the flexible substrate 11 uniformly inward on both sides with the central axis 112 as the axis of symmetry, forming a symmetrical bending profile that matches the curvature of the outer wall of the guide pin 3. This is beneficial for the flexible substrate 11 to uniformly wrap the guide pin 3 from both sides, reducing the situation of insufficient or excessive wrapping on one side, and improving the adhesion quality of the flexible substrate 11 uniformly wrapping the guide pin 3 from both sides.

[0079] The groove width of the groove 111 near the central axis 112 is greater than that of the groove 111 away from the central axis 112. This results in a larger volume of the first coating 21 filling the central region of the flexible substrate 11 near the central axis 112, and a correspondingly larger stress generated by the curing expansion of the first coating 21, thus applying a stronger bending driving force in the central region. During the bending of the flexible substrate 11 towards the lower surface, the degree of bending in the central region is relatively greater. Therefore, providing a wider groove 111 in the central region to fill more of the first coating 21 is beneficial for generating a greater bending driving force in this region, allowing the central region to bend sufficiently to match the curvature of the guide pin 3. The edge region is farther from the bending neutral surface, and the required bending driving force is relatively smaller. Therefore, providing a narrower groove 111 can meet the bending requirements while retaining more continuous flexible substrate 11 material to maintain the structural integrity of the edge region.

[0080] Furthermore, the wider central groove 111 allows for a greater filling of the first coating 21 in the central region, requiring a longer time for bodily fluids to penetrate deep into the central groove 111 and soften. Conversely, the narrower edge grooves 111 fill less of the first coating 21, resulting in a faster fluid penetration rate. This allows the first coating 21 in the central region of the flexible substrate 11 to maintain its hardness for a longer period than in the edge region. During implantation, the central region, as the area most concentrated with bending moments and axial forces, benefits from its longer-lasting hardness, which helps provide reliable axial support for the flexible electrode 1 even in the later stages of implantation.

[0081] The distance between two adjacent grooves 111 near the central axis 112 is less than the distance between two adjacent grooves 111 away from the central axis 112. Here, the distance refers to the interval between two adjacent grooves 111 in the width direction of the flexible substrate 11, that is, the distance between the nearest edges of the two grooves 111, or the distance between the midpoints of the two grooves 111.

[0082] The grooves 111 in the central region are arranged more densely, dividing the flexible substrate 11 in this region into more narrow strip structures. Each narrow strip is subjected to stress from the curing and expansion of the first coating 21 in the adjacent grooves 111. The narrow strip structures in the central region have lower stiffness and are subjected to more concentrated expansion stress, making them more prone to bending deformation. This facilitates the formation of larger bends in the central region during the curing process of the first coating 21. Simultaneously, the smaller spacing between the grooves 111 in the central region enhances the superposition effect of the expansion stress fields of the first coating 21 in adjacent grooves 111. The combined force forms a more concentrated bending driving force in the central region, further promoting bending deformation. The grooves 111 in the edge region have larger spacing, preserving more continuous flexible substrate 11 material. This continuous material has higher in-plane stiffness, providing structural support for the edges of the flexible substrate 11 during bending. This allows the edge region to maintain its structural integrity while following the bending of the central region, preventing tearing due to excessive segmentation.

[0083] The grooves 111 in the central region are more densely packed, and the total amount of the first coating 21 is larger. The narrow strip-shaped flexible substrate 11 between adjacent grooves 111 creates some resistance to the penetration of body fluid into the depth of the grooves 111, making the softening process of the first coating 21 in the groove group 111 in the central region slower. The grooves 111 in the edge region are more spaced, and body fluid seeps in from the opening of the grooves 111 and the wide gap between the grooves 111, allowing the first coating 21 in the edge grooves 111 to be infiltrated and softened by body fluid relatively earlier, forming a differentiated softening mode of slow softening in the middle and early softening at the edges. This allows the softening process of the flexible substrate 11 after implantation to proceed gradually from the edges to the center. The edge region of the flexible electrode 1 first recovers its flexibility to adapt to tissue micromovement, while the central region maintains a higher hardness to maintain axial support.

[0084] Therefore, by adopting a "dense in the middle and sparse at the edges" groove spacing distribution, a more concentrated and intense curing expansion driving force can be generated in the central region of the flexible substrate 11, improving the sufficiency of bending deformation in the central region and the tightness of matching with the outer wall of the guide pin 3. At the same time, the retention of more continuous material in the edge region helps to maintain the structural integrity of the edge and prevents the edge region structure from weakening due to excessively dense grooves.

[0085] From the perspective of maintaining post-implantation hardness, the denser grooves 111 and the greater amount of first coating 21 filling in the central region can prolong the time the central region maintains high hardness, which is beneficial for providing reliable axial support for the long implantation stroke of the flexible electrode 1 in deep implantation scenarios. The relatively faster softening of the edge region allows the edge part of the flexible electrode 1 to recover its flexibility earlier after implantation, reducing damage to the tissue in the edge region. The differentiated softening mode between the central region and the edge enables the flexible electrode to gradually recover its flexibility from the outside to the inside and from the edge to the center. During the transition phase of the flexible electrode 1's recovery of flexibility, the structural stability of the core region is maintained, reducing the risk of electrode position displacement due to uniform softening.

[0086] like Figure 2 , Figure 3 , Figures 6-10 , Figures 14-17 As shown, a protrusion 31 is formed on the outer wall of the guide pin 3. The protrusion 31 is located at the distal end of the electrode point 12 along the axial direction and corresponds to the electrode point 12 in cross-section. That is, the protrusion 31 is axially aligned with the electrode point 12, but is located at the distal end of the electrode point 12.

[0087] The protrusion 31 refers to an outwardly protruding structure on the outer wall of the guide needle 3, corresponding to the distal region of the electrode point 12. Since the flexible substrate 11 is attached to the outer wall of the guide needle 3, and the electrode point 12 is located on the upper surface of the flexible substrate 11 and protrudes from it, the protrusion 31 on the outer wall of the guide needle 3 is located below the flexible substrate 11, corresponding to the position directly in front of the electrode point 12. When the guide needle 3 needs to be removed after the flexible electrode 1 is implanted, the protrusion 31, which is driven to move proximally, exerts a bottom-up local pushing force on the flexible substrate 11, causing the electrode point 12 and the second coating 22 filling the window 211 to deform outward accordingly, leading to the rupture of the second coating 22.

[0088] This embodiment is particularly beneficial in the following scenario: After the flexible electrode 1 is implanted, the second coating 22 in the window 211 is not completely dissolved, causing the electrode point 12 to remain covered by the second coating 22 and preventing immediate subsequent diagnosis and / or treatment. Waiting for the body fluid to infiltrate and dissolve the coating may be time-consuming. Therefore, a protrusion 31 is provided on the distal outer wall of the guide needle 3. By utilizing the necessary step of removing the guide needle 3, an outward mechanical force is applied to the possibly undissolved second coating 22, forcing it to crack, thereby disrupting its structural integrity and / or increasing the contact area with body fluid, thus promoting its detachment or accelerating its dissolution, shortening the time to subsequent diagnosis and / or treatment, and improving electrode deployment efficiency.

[0089] In one embodiment, the protrusion 31 is an axially extending ridge, with at least its proximal end being a slope. An ridge refers to a generally elongated protrusion of the protrusion 31 extending along the axial direction of the guide needle 3, i.e., the length direction of the ridge is consistent with the length direction of the guide needle 3. At least its proximal end being a slope means that the ridge structure has a surface morphology with a sloping transition at least in its proximal portion. It should be noted that the terms "proximal," "distal," "anterior," and "posterior" in this document are relative to the physician manipulating the electrode assembly. "Proximal" and "posterior / side" refer to the side closer to the physician's handheld control end, and correspondingly, "distal" and "anterior / side" refer to the side farther from the physician or the side that first enters the subject's body. For example, with... Figure 1 For example, the tip on the left side of electrode assembly 100 is the distal end, and the tip on the right side is the proximal end. It should be understood that these directional terms are definitions for ease of description and are not restrictive or absolute. A slope is an inclined surface in which the height of the edge gradually increases from the proximal end to the distal end, or a gradually transitioning surface where the edge has no height at the proximal end.

[0090] The protrusion 31 adopts the shape of an axially extending ridge, so that the pushing force of the protrusion 31 on the flexible substrate 11 and the second coating 22 is continuously distributed along the axial direction. The axially extending ridge forms a linear or continuous pushing force on the second coating 22 in the window 211 region, which is beneficial to the uniform thinning of the second coating 22 during the dissolution process. The proximal end is set as a slope, so that the height of the ridge has a gradually changing profile at the proximal end, avoiding a sudden height jump at the proximal end of the ridge. During the process of the guide pin 3 being withdrawn from the flexible electrode 1, the guide pin 3 withdraws in the proximal direction. The existence of the slope allows the ridge to gradually push against the second coating 22 outside the electrode point 12, reducing the obstruction of the ridge by the flexible substrate 11 and ensuring that the guide pin 3 can be smoothly withdrawn.

[0091] In another embodiment, the protrusion 31 includes a plurality of axially spaced protrusions, each protrusion having a rounded outer surface. The protrusion 31 is configured as a plurality of axially spaced protrusions, meaning that the protrusion 31 at the distal position corresponding to the electrode point 12 on the outer wall of the guide pin 3 is composed of a plurality of discrete point-like protrusions. These protrusions are arranged sequentially along the axial direction of the guide pin 3 and maintain a certain distance from each other. "Rounded" means that the outer contour of the protrusion has a smooth curved surface shape, without sharp edges or abrupt surface features, such as a hemispherical, ellipsoidal, or other curved surface with continuous curvature.

[0092] Multiple protrusions are arranged at intervals along the axial direction, distributing the pushing force on the second coating 22 across multiple discrete points. The gaps between the protrusions do not exert a pushing force on the flexible substrate 11 or the second coating 22. Thus, during the proximal removal of the guide pin 3, the spaced protrusions intermittently exert an outward pushing force on the second coating 22, causing the flexible substrate 11 to intermittently bulge and contract at the corresponding electrode point 12. Therefore, the undissolved second coating 22 will undergo fluctuating, repeated deformation, accelerating its detachment. The intermittent bulging and contraction of the flexible substrate 11 at the corresponding electrode point 12 refers to the following: when the guide pin 3 is removed proximally until the protrusions align with the electrode point 12, the flexible substrate 11 is deformed by being pushed outward by the protrusions. Conversely, when the guide pin 3 is removed proximally until the area between two protrusions aligns with the electrode point 12, the flexible substrate 11 retracts inward due to the springback of its own material.

[0093] The protrusion 31 has at least a first section whose height gradually increases from near to far. Height refers to the radial distance from the base surface of the outer wall of the guide pin 3 to the top of the protrusion 31. The gradual increase in height of the first section can be linear or non-linear, for example, increasing according to a convex or concave curve. The first section of the protrusion 31, with its gradually increasing height from near to far, can exert a gradually increasing pushing force on the second coating 22 during the proximal removal of the guide pin 3, causing the height of the second coating 22 to be pushed outwards to gradually increase. Therefore, as the proximal removal stroke of the guide pin 3 increases, the degree of outward deformation of the second coating 22 also increases, thereby promoting its pyrolysis and detachment.

[0094] The protrusion 31 also has a second section whose height gradually decreases from near to far, located at the far end of the first section. The height of the protrusion 31 gradually increases in the first section, reaching its peak at the junction of the first and second sections, and then gradually decreases in the second section. Overall, the protrusion 31 presents a raised shape that is high in the middle and low at both ends. The second section is the far end of the protrusion 31, and its height gradually decreases from near to far, meaning that the height of the protrusion gradually decreases from the junction of the first and second sections towards the far end. Similarly, the far end of the second section is a slope, or its height gradually decreases until the far end is flush with the outer wall of the guide pin 3. The protrusion 31 includes a second section located at the far end of the first section and gradually decreasing in height from near to far, which allows the flexible substrate 11 and the second coating 22 to gradually retract after being pushed outward to the highest point by the gradually increasing first section, avoiding structural damage caused by the drastic contraction and deformation of the flexible substrate 11 due to the sudden drop in height.

[0095] The first coating 21 covers most of the outer wall of the guide needle 3, which facilitates the removal of the guide needle 3 after implantation. Since the first coating 21 is in a fully wetted third state at this time, and its inner surface is also lubricated, there is less friction with the guide needle 3. Therefore, the guide needle 3 can be easily removed.

[0096] In addition, such as Figure 2 and Figure 3 As shown, the first coating 21 covers most of the area of ​​the flexible electrode 1 except for the electrode point 12, and the two form a structurally integrated whole. Therefore, the first coating 21 plays a structural stabilizing role for the flexible electrode 1, thereby preventing the flexible electrode 1 from shifting when the guide pin 3 is removed.

[0097] This application also provides a method for manufacturing the electrode assembly 100 as described in the above embodiments, comprising:

[0098] S10, Fabrication of flexible electrode 1. Fabrication of flexible electrode 1 refers to forming electrode points 12 and electrode wires on a flexible substrate 11 using micro-nano fabrication processes, thereby obtaining a flexible electrode 1 comprising a flexible substrate 11 and electrode points 12 protruding from the upper surface of the flexible substrate 11. For example... Figure 4 As shown, the specific steps may include: depositing a first sacrificial layer 14 on a rigid substrate 13; forming a first flexible layer on the first sacrificial layer 14; forming a conductive layer on the first flexible layer and patterning the conductive layer using a patterning process to form electrode points 12 and electrode wires (not shown); depositing a second flexible layer on the first flexible layer, the first and second flexible layers together being referred to as a flexible substrate 11; and creating openings in the second flexible layer to expose the electrode points 12. Figure 5 As shown, the first sacrificial layer 14 is removed, and the rigid substrate 13 is peeled off from the flexible substrate 11 to form the flexible electrode 1. The flexible substrate 11 can be electroplated to increase the height of the protrusion of the electrode point 12.

[0099] S20, a first coating 21 is formed on the flexible electrode 1. Forming the first coating 21 on the flexible electrode 1 means covering the outer surface of the flexible electrode 1 with the material of the first coating 21 and curing it. The first coating 21 is provided with a window 211 for the electrode point 12 to be exposed.

[0100] S30, a second coating 22 is formed on the flexible electrode 1. Forming the second coating 22 on the flexible electrode 1 means that the material of the second coating 22 fills the window 211 and covers the outer surface of the electrode point 12, so that the electrode point 12 is wrapped by the second coating 22.

[0101] By breaking down the fabrication of the electrode assembly 100 into three steps—preparing the flexible electrode 1, forming the first coating 21, and forming the second coating 22—clear process interfaces and quality control points are established between each step. The sequence of preparing the flexible electrode 1 first, followed by the sequential formation of the two coatings, ensures that the flexible electrode 1, as the basic structure, is completed before the coating is applied, avoiding the waste of materials and time caused by continuing the coating process if the flexible electrode 1 itself has defects. The first coating 21 is formed before the second coating 22, ensuring that the first coating 21 completely covers the outer surface of the flexible electrode 1 and forms a window 211, providing a clear geometric reference and accommodating space for the subsequent filling of the second coating 22. The second coating 22 is filled into the window 211 after the first coating 21 is formed, using the boundary of the window 211 as a positioning and limiting reference, which is beneficial for controlling the filling range and thickness of the second coating 22.

[0102] Therefore, adopting a three-step manufacturing method can improve the controllability and standardization of the electrode assembly 100 manufacturing process. Each step is completed before proceeding to the next, which facilitates the timely detection and elimination of process defects, thereby improving the yield of the final product. Simultaneously, step-by-step manufacturing allows for the selection of appropriate manufacturing conditions based on the process requirements of different materials and structures, avoiding process interference between different coating materials and improving the forming quality of each coating.

[0103] like Figures 4-10 As shown, it provides a method for making such Figure 2 and Figure 2A An embodiment of a method for forming an electrode assembly is shown. In this embodiment, the step of forming the first coating 21 includes:

[0104] S211, attach the flexible electrode 1 to the guide pin 3. For example... Figure 6 As shown, at this time, the flexible electrode 1 is attached to the outer wall of the guide needle 3 under the action of gravity.

[0105] S212, such as Figure 6 As shown, the flexible electrode 1 and the guide pin 3 are placed horizontally, with the groove 111 on the upper surface of the flexible substrate 11 facing upwards.

[0106] S213, such as Figure 7As shown, an aqueous solution of the first coating 21 is dripped into the groove 111 from above. "Dripping" refers to using a precision dispensing tool such as a micropipette or dispensing needle to drip the aqueous solution of the first coating 21 into the groove 111 in a droplet manner. The dispensing tool is positioned approximately 1-2 cm above the flexible electrode 1 and the guide needle 3, with the outlet aligned with the groove 111 located in the center of the upper surface of the flexible substrate 11. The valve of the dispensing tool is opened, and the aqueous solution of the first coating 21 drips into the groove 111 under the influence of gravity. After the groove 111 is filled, it overflows to both sides of its width, gradually covering the surfaces of both sides of the flexible substrate 11.

[0107] S214, Perform a curing operation on the aqueous solution of the first coating 21. The curing operation refers to the process of causing the aqueous solution to undergo a cross-linking reaction and solidify into a shape by means of light, heat, humidification, or other suitable methods, depending on the material of the first coating 21. The aqueous solution is a liquid solution obtained by dissolving the solid material or prepolymer of the first coating 21 in a solvent.

[0108] It should be noted that in some cases, the curing speed of the aqueous solution of the first coating 21 is relatively fast. For example, the first coating 21 uses a photocurable hydrogel, which can achieve micro-curing in seconds (the aqueous solution loses its fluidity) by UV light irradiation. Since there is a subsequent operation where the aqueous solution of the first coating 21 covers the entire outer surface of the guide pin 3 and its corresponding curing operation, the curing operation in this subsequent step is more thorough (e.g., longer UV light irradiation time). Therefore, in step S214, the micro-curing of the aqueous solution of the first coating 21 has met the requirements.

[0109] Therefore, steps S213 and S214 are not limited in their order; rather, it is better to perform the two steps simultaneously, as this can improve curing efficiency. Furthermore, when performing step S213, it is also preferable to simultaneously rotate the guide pin 3, with the rotation range such that the outermost edges of the grooves 111 on both sides of the width face upwards to receive the dripping first coating 21 aqueous solution. Since the curing operation is performed simultaneously with the dripping of the first coating 21 aqueous solution, the rotation operation will not cause the first coating 21 to peel off; instead, it can make the thickness of the first coating 21 more uniform.

[0110] By employing a dripping process, the aqueous solution of the first coating 21 is filled into the groove 111. Utilizing the fluidity of the aqueous solution, it flows naturally into and fills the groove 111 under gravity, further covering the upper surface and sides of the flexible substrate 11. The curing of the aqueous solution of the first coating 21 in the groove 111 creates a compressive force on the two side walls of the groove 111 in the width direction, causing the flexible substrate 11 to bend. This improves the adhesion between the flexible substrate 11 and the guide pin 3, ensuring complete adhesion between the lower surface of the flexible substrate 11 and the outer surface of the guide pin 3. This complete adhesion eliminates air between the lower surface of the flexible substrate 11 and the outer surface of the guide pin 3, preventing the formation of air gaps between them during the subsequent step of completely covering the outer wall of the guide pin 3 with the first coating 21.

[0111] Those skilled in the art will understand that air gaps in implantable devices are extremely dangerous for patients. Air gaps reduce the structural strength of the area where they are located, and during implantation and subsequent diagnosis and / or treatment, the device inevitably deforms, such as bending. This can lead to structural damage, causing air leakage and potentially forming an air embolism. The solution in this embodiment, by using a first coating 21 to at least fill and cure the groove 111 on the upper surface of the flexible substrate 11, promotes complete adhesion between the flexible substrate 11 and the guide needle 3, avoiding the formation of air gaps in the electrode assembly. This significantly improves product yield and safety.

[0112] Furthermore, the first coating 21, which overflows to both sides of the width of the flexible substrate 11, covers it and acts as an adhesive medium between the upper surface of the flexible substrate 11 and the guide pin 3, preventing the flexible substrate 11 from warping and separating from the outer wall of the guide pin 3. The first coating 21, which is cured in the groove 111, constrains the flexible substrate 11 from above, so that the flexible substrate 11 is held between the guide pin 3 and the first coating 21, which is conducive to the stable attachment of the flexible electrode 1 and the guide pin 3.

[0113] like Figure 8 As shown, in one embodiment, after step S214, a dripping process can be used to form a first coating 21 on the surface of other areas of the guide pin 3. Specifically, this includes:

[0114] S215, rotate the flexible electrode 1 and the guide pin 3, and drip an aqueous solution of the first coating 21 onto the outer surface of other parts of the flexible electrode 1 and the guide pin 3 from above until the aqueous solution of the first coating 21 completely covers the outer surface of the flexible electrode 1 and the guide pin 3. Rotation refers to circumferentially rotating the flexible electrode 1 and the guide pin 3 about their longitudinal axis, so that the outer surface area of ​​the guide pin 3 that was previously not coated with the first coating 21 aqueous solution due to its downward orientation is now in an upward position, facilitating the dripping coating onto this area from above. Other parts refer to the outer surface area of ​​the flexible electrode 1 and the guide pin 3 other than the area of ​​the groove 111.

[0115] S216, perform the curing operation again. The curing process depends on the material of the first coating 21, as described above, and will not be repeated here.

[0116] In this embodiment, after the first coating 21 in the groove 111 has cured, the other outer surface areas of the flexible electrode 1 and the guide pin 3 are not yet covered by the first coating 21. By rotating the flexible electrode 1 and the guide pin 3 and continuing to drip the aqueous solution of the first coating 21 from above, the various circumferential outer surface areas of the flexible electrode 1 and the guide pin 3 can be gradually covered. After each rotation, the uncovered area is turned to an upward position, and gravity causes the newly dripped aqueous solution to spread on the surface of the area and form a continuous coverage with the cured first coating 21 in the groove 111 area. Using a rotating and area-by-area dripping coating method helps maintain the continuity of the first coating 21 manufacturing process. Performing the curing operation again allows the coating of the newly coated area to combine with the previously cured coating of the groove 111 area, forming a continuous and complete first coating 21 coverage. Therefore, by using a rotating dripping process to gradually achieve all-round coverage of the outer surface of the flexible electrode 1 and the guide pin 3, it is beneficial to control the coating uniformity of the first coating 21 in each area.

[0117] like Figure 8 As shown, in another embodiment, after step S214, a first coating 21 can be formed on the surface of other areas of the guide pin 3 using a wetting process. Specifically, this includes:

[0118] S217, the flexible electrode 1 and the guide pin 3 are immersed in the aqueous solution of the first coating 21. Immersion means that the flexible electrode 1 and the guide pin 3, which have been pre-fixed in steps S211-S214, are completely immersed in the aqueous solution of the first coating 21, so that the aqueous solution fully contacts and covers the entire outer surface of the flexible electrode 1 and the guide pin 3.

[0119] S218, a flexible electrode 1 and a guide needle 3 are proposed. "Proposed" refers to slowly extracting the flexible electrode 1 and the guide needle 3 upwards from the aqueous solution, where the aqueous solution adheres to the outer surfaces of the flexible electrode 1 and the guide needle 3, forming a liquid film.

[0120] S219, perform a curing operation on the aqueous solution of the first coating 21 on the surfaces of the flexible electrode 1 and the guide pin 3.

[0121] In this embodiment, after the first coating 21 in the groove 111 has cured, an impregnation process is used to form a first coating 21 covering the remaining outer surfaces. The impregnation process can ensure that all outer surfaces of the flexible electrode 1 and the guide pin 3 are uniformly contacted with the aqueous solution in one step, and the operation steps are simple and efficient. The curing operation is carried out simultaneously during the extraction process, so that the liquid film is quickly shaped and the uneven thickness of the liquid film due to gravity flow is avoided.

[0122] Therefore, the immersion process simplifies the coating operation of the first coating 21, improving production efficiency. Simultaneously, the immersion method ensures uniform contact of the aqueous solution across all areas of the outer surface, resulting in a more uniform coating thickness distribution. Furthermore, using the immersion process to complete the overall coating on the pre-cured first coating 21 in the groove 111 area facilitates the seamless integration of the precision filling and overall coating processes, ensuring both the accuracy of the groove 111 area's fitting and the uniformity of the overall surface coating.

[0123] like Figure 9 As shown, before forming the second coating 22, the process also includes:

[0124] S31, the first coating 21 at the location of the corresponding electrode point 12 is removed to form a window 211 for exposing the electrode point 12. The removal can be performed by laser ablation, mechanical peeling or chemical dissolution, etc., to partially remove the first coating 21 covering the electrode point 12, so that the electrode point 12 is exposed from the first coating 21.

[0125] like Figure 10 As shown, the second coating 22 can be formed using an impregnation process, specifically including:

[0126] S32, the flexible electrode 1 and the guide pin 3, which are wrapped by the first coating 21, are immersed in the aqueous solution of the second coating 22.

[0127] S33, proposes flexible electrode 1 and guide pin 3.

[0128] S34, perform a curing operation on the aqueous solution of the second coating 22 that adheres to the surface of the first coating 21 and fills the window 211.

[0129] Window 211 is formed by removing the first coating 21. After window 211 is formed, a second coating 22 is formed using an immersion process, in which the entire electrode assembly 100 is re-immersed in an aqueous solution of the second coating 22. The aqueous solution fills the window 211, covering the electrode points 12, and also adheres to the outer surface of the first coating 21. After removal and curing, the formation of the second coating 22 in both the window 211 and the surface of the first coating 21 is completed simultaneously. The immersion process for forming the second coating 22 is simple and efficient, and the immersion method facilitates the full penetration of the aqueous solution of the second coating 22 into the window 211 and close contact with the surface of the electrode points 12.

[0130] like Figures 12-17 As shown, it provides a method for making such Figure 3 and Figure 3A An embodiment of a method for forming an electrode assembly is shown. In this embodiment, the step of forming the first coating 21 includes:

[0131] S221, as Figure 14As shown, the flexible electrode 1 is attached to the guide needle 3.

[0132] S222, as Figure 15 As shown, the flexible electrode 1 and the guide pin 3 are horizontally immersed in the aqueous solution of the first coating 21, with the groove 111 on the upper surface of the flexible substrate 11 facing upward.

[0133] S223 proposes a flexible electrode 1 and a guide pin 3.

[0134] S224, perform a curing operation on the aqueous solution of the first coating 21 on the surfaces of the flexible electrode 1 and the guide pin 3.

[0135] The immersion process simultaneously fills the groove 111 and coats the entire outer surface, reducing manufacturing steps and shortening the manufacturing cycle, thus improving the production efficiency of the electrode assembly 100. Furthermore, the upward orientation of the groove 111 ensures that gravity maintains sufficient filling of the aqueous solution during the extraction process, simplifying the process while preserving the filling effect of the groove 111.

[0136] like Figure 11 As shown, the step of fabricating the flexible electrode 1 includes: S11, a flexible substrate 11 is formed on a rigid substrate 13, and a first sacrificial layer 14 is provided between the lower surface of the flexible substrate 11 and the upper surface of the rigid substrate 13 (as described above). The rigid substrate 13 refers to a rigid substrate used to support the flexible substrate 11 during micro-nano fabrication, typically a silicon wafer or glass sheet. The first sacrificial layer 14 refers to a removable material layer disposed between the flexible substrate 11 and the rigid substrate 13, which can be made of any suitable existing material, including silicon oxide materials such as thermally oxidized SiO2, organic polymer materials such as photoresist, and metal sacrificial layers such as copper or nickel. Removing the first sacrificial layer 14 allows the flexible substrate 11 to be peeled off from the rigid substrate 13.

[0137] Before the formation of the first coating 21, the following are also included:

[0138] S12, as Figure 11 As shown, a second sacrificial layer 15 is laid on the upper surface of the flexible substrate 11 to completely cover the electrode point 12 and the upper surface of the flexible substrate 11.

[0139] S13, as Figure 12 As shown, a portion of the second sacrificial layer 15 is selectively removed, leaving only the portion of the second sacrificial layer 15 covering the electrode point 12.

[0140] S14, as Figure 13 As shown, the first sacrificial layer 14 is removed and the rigid substrate 13 is peeled off.

[0141] The second sacrificial layer 15 is a temporary protective layer that can be selectively removed in a specific manner. A portion of the second sacrificial layer 15 is selectively removed, leaving only the portion covering the electrode point 12, thus shielding the upper surface of the flexible substrate 11 at the electrode point 12. This prevents the electrode point 12 from being covered by the first coating 21 during the subsequent wetting process (steps S221-S224). Then, by removing the second sacrificial layer 15, the electrode point 12 is re-exposed, allowing the second coating 22 to be formed.

[0142] Compared to the case where the first sacrificial layer 14 exists only in a flat form during steps S11-S14 (e.g.) Figures 11-13 As shown), the second sacrificial layer 15 is in steps S221-S224 (as shown). Figures 14-15 The second sacrificial layer 15 exists in a curved form to accommodate the bending of the flexible electrode 1 onto the outer surface of the guide pin 3. Therefore, the second sacrificial layer 15 needs to have better extensibility than the first sacrificial layer 14 to better adhere to the guide pin 3. Figure 14 The straight shape transitions to Figure 15 , Figure 16 The second sacrificial layer 15 has a curved shape. The better extensibility of the second sacrificial layer 15 makes this transition possible and avoids the adverse effects that this transition may have. For example, it minimizes the reverse contraction force on the upper surface of the flexible substrate 11 due to stretching, ensuring that the flexible substrate 11 achieves the desired bending and attaches to the guide pin 3.

[0143] Since the first sacrificial layer 14 is used to separate the flexible substrate 11 from the rigid substrate 13, it exists almost simultaneously with the rigid substrate 13 (except for the final separation operation). Therefore, the material ductility of the first sacrificial layer 14 is not particularly required. However, due to bending requirements, the second sacrificial layer 15 can only be selected from the above examples of materials with better ductility, such as copper or nickel.

[0144] Because the impregnation process results in all the outer surfaces of the impregnated material being coated with the impregnating material, in the step of forming the first coating 21, the first coating 21 encapsulates the second sacrificial layer 15.

[0145] like Figure 16 As shown, before forming the second coating 22, the second sacrificial layer 15 is removed to form a window 211 for exposing the electrode point 12. The method for removing the sacrificial layer is related to the material used and is well known in the art, so it will not be described in detail. Since the space originally occupied by the second sacrificial layer 15 is released after the second sacrificial layer 15 is removed, a window 211 corresponding to the position of the electrode point 12 is formed in the first coating 21, exposing the electrode point 12.

[0146] By using the second sacrificial layer 15 as a temporary occupant structure for the electrode point 12, the first coating 21 is wrapped around the outer surface of the second sacrificial layer 15 during its formation. When the second sacrificial layer 15 is removed, the space it occupies naturally becomes the window 211, thus exposing the electrode point 12. The method of first fully laying the second sacrificial layer 15 and then selectively removing it allows for precise control of the position and size of the retained area, thereby ensuring the alignment accuracy between the window 211 and the electrode point 12. At the same time, the removal of the first sacrificial layer 14 is carried out after the selective removal of the second sacrificial layer 15, ensuring that the flexible substrate 11 completes the patterning process of the second sacrificial layer 15 under the support of the rigid substrate 13, avoiding the need to perform fine patterning processing on the soft flexible substrate 11 without rigid support.

[0147] The step of forming the second coating 22 includes filling the window 211 with material for the second coating 22, wherein the amount of material for the second coating 22 is configured such that the outer surface of the second coating 22 after curing is not lower than the outer surface of the first coating 21. The filling of the second coating 22 material can be performed by injection, and the amount refers to the volume or mass of the second coating 22 material filled into the window 211. "Not lower than the outer surface of the first coating 21" means that, in the thickness direction of the flexible substrate 11, the outer surface of the second coating 22 is flush with or slightly higher than the outer surface of the first coating 21. By controlling the amount of the second coating 22, the surface of the finally cured second coating 22 is not lower than the surface of the first coating 21. The advantages of having a flush height between the two outer surfaces of the coatings are described above and will not be repeated here.

[0148] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. An electrode assembly, characterized in that, include: A flexible electrode includes: a flexible substrate and electrode points protruding from the upper surface of the flexible substrate; Variable hardness coatings, including: The first coating at least partially covers the outer surface of the flexible electrode and has windows for exposing the electrode points; The second coating, at least filling the window, covers the outer surface of the electrode point; When the flexible electrode is located outside the subject, the first coating is in a first state and has a first hardness that is uniform along its thickness direction; the first hardness is greater than the hardness of the flexible substrate, and the outer surface of the second coating is not lower than the outer surface of the electrode point. During the implantation of the flexible electrode into the target tissue in the subject's body, the first coating is in a second form, with its outer portion having a second hardness lower than the first hardness or equivalent to the hardness of the flexible substrate, and its inner portion having a third hardness equivalent to the first hardness; the second coating gradually dissolves and thins, and the electrode points are gradually exposed in the window; the second form is configured to be obtained after the outer portion of the first coating in the first form is soaked in the subject's body fluid. After the flexible electrode is positioned in the target tissue of the subject, the first coating is in the third form, which has a fourth hardness that is uniform along its thickness direction and is comparable to the second hardness; the second coating is completely dissolved, and the electrode point is exposed to the maximum extent in the window; the third form is obtained by configuring the inner part of the first coating in the second form to be wetted by the subject's body fluid.

2. The electrode assembly according to claim 1, characterized in that, The second coating is circumferentially continuous and covers the outer surface of the first coating and the outer surface of the electrode points.

3. The electrode assembly according to claim 2, characterized in that, The ratio of the depth of the window to the thickness of the portion of the second coating covering the outer surface of the first coating is between 4:1 and 4.2:

1.

4. The electrode assembly according to claim 1, characterized in that, The second coating is circumferentially discontinuous, filling only the window area.

5. The electrode assembly according to claim 4, characterized in that, The outer surface of the second coating is not lower than the outer surface of the first coating.

6. The electrode assembly according to claim 1, characterized in that, The width of the window is greater than the width of the electrode point.

7. The electrode assembly according to any one of claims 1 to 6, characterized in that, The electrode assembly also includes a guide pin, the lower surface of which is attached to the outer wall of the guide pin, and the first coating and the flexible electrode together cover the outer wall of the guide pin. The upper surface of the flexible substrate has grooves, and the first coating fills the grooves.

8. The electrode assembly according to claim 7, characterized in that, There are multiple grooves, which are spaced apart along the width direction of the flexible substrate; The grooves are arranged symmetrically along the central axis of the flexible substrate, but in any two adjacent grooves, the groove width of the groove closer to the central axis is greater than the groove width of the groove farther away from the center of the flexible substrate.

9. The electrode assembly according to claim 8, characterized in that, The distance between two adjacent grooves closer to the central axis is less than the distance between two adjacent grooves farther from the central axis.

10. The electrode assembly according to claim 7, characterized in that, The outer wall of the guide pin has a protrusion located at the distal end of the electrode point, which is axially aligned with the electrode point.

11. The electrode assembly according to claim 10, characterized in that, The protrusion is an axially extending ridge, with at least its proximal end being a slope; or, The protrusion comprises multiple protrusions spaced apart along the axial direction, each protrusion having a rounded outer surface.

12. The electrode assembly according to claim 10, characterized in that, The protrusion has at least a first segment whose height gradually increases from near to far.

13. The electrode assembly according to claim 12, characterized in that, The protrusion also has a second segment whose height gradually decreases from near to far, and the second segment is located at the far end of the first segment.

14. A method for manufacturing an electrode assembly as described in any one of claims 1 to 13, characterized in that, include: Fabrication of flexible electrodes; A first coating is formed on the flexible electrode; A second coating is formed on the flexible electrode.

15. The method according to claim 14, characterized in that, The steps for forming the first coating include: Attach the flexible electrode to the guide needle; The flexible electrode and guide pin are placed horizontally with the groove on the upper surface of the flexible substrate facing upwards; An aqueous solution for the first coating drips from above into the groove; A curing operation is performed on the first coating aqueous solution.

16. The method according to claim 15, characterized in that, Following the step of curing the first coating aqueous solution, the process also includes: Rotate the flexible electrode and guide needle, and drip the aqueous solution of the first coating onto the outer surface of other parts of the flexible electrode and guide needle from above until the aqueous solution of the first coating completely covers the outer surface of the flexible electrode and guide needle. Perform the curing operation again.

17. The method according to claim 15, characterized in that, Following the step of curing the first coating aqueous solution, the process also includes: The flexible electrode and the guide pin are immersed in an aqueous solution of the first coating. A flexible electrode and a guide pin are proposed; A curing process is performed on the first coating aqueous solution on the surfaces of the flexible electrode and the guide pin.

18. The method according to claim 14, 16 or 17, characterized in that, Before the step of forming the second coating, the method further includes: removing the first coating at the location of the corresponding electrode point to form a window for exposing the electrode point; The steps for forming the second coating include: The flexible electrode and guide needle, which are coated with the first coating, are immersed in an aqueous solution of the second coating. A flexible electrode and a guide pin are proposed; A curing operation is performed on the aqueous solution of the second coating that adheres to the surface of the first coating and fills the window.

19. The method according to claim 14, characterized in that, The steps for forming the first coating include: Attach the flexible electrode to the guide needle; The flexible electrode and guide pin are horizontally immersed in the aqueous solution of the first coating, with the groove on the upper surface of the flexible substrate facing upwards. A flexible electrode and a guide pin are proposed; A curing process is performed on the first coating aqueous solution on the surfaces of the flexible electrode and the guide pin.

20. The method according to claim 14, characterized in that, The steps for fabricating a flexible electrode include: a flexible substrate is formed on a rigid substrate, and a first sacrificial layer is provided between the lower surface of the flexible substrate and the upper surface of the rigid substrate; Prior to the step of forming the first coating, the following steps are also included: A second sacrificial layer is deposited on the upper surface of the flexible substrate to completely cover the electrode points and the upper surface of the flexible substrate. Selectively remove part of the second sacrificial layer, retaining only the portion of the second sacrificial layer covering the electrode points; Remove the first sacrificial layer and peel off the rigid substrate; In the step of forming the first coating, the first coating encapsulates the second sacrificial layer; Prior to the step of forming the second coating, the second sacrificial layer is removed to form windows for exposing the electrode points.

21. The method according to claim 20, characterized in that, The second sacrificial layer has greater extensibility than the first sacrificial layer.

22. The method according to claim 18, characterized in that, The step of forming the second coating includes: filling the window with the material of the second coating, wherein the amount of the material of the second coating is configured such that the outer surface of the second coating formed after its curing is not lower than the outer surface of the first coating.

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