A trans-interface deep-pore array neural electrode capable of storing conductive polymer and its preparation method

Abstract

This invention provides a trans-interface deep-hole array neural electrode capable of storing conductive polymer and its fabrication process. The neural electrode includes a substrate layer, a conductive layer, a top encapsulation layer, and a conductive polymer PEDOT:PSS coating. A trans-interface deep-hole array is distributed within the exposed surface of the electrode points, penetrating the conductive layer and forming blind holes within the substrate layer. PEDOT:PSS fills the deep-hole array and covers the exposed surface of the electrode points. The deep-hole array, like a reservoir, stores the conductive polymer PEDOT:PSS, exhibiting excellent charge storage and injection capabilities, providing an innovative solution for neural electrodes used for long-term signal acquisition and electrical stimulation. This invention overcomes common surface modification methods for neural electrodes by utilizing a deep-hole array penetrating the conductive layer to accumulate modified material in the depth direction. This allows the electrode to withstand the effects of partial or complete detachment of the coating material from the top surface of the electrode points and within the deep holes, maintaining good electrochemical performance. Furthermore, the novel structure and simple process effectively solve the key problem of easy detachment and failure of the conductive polymer coating material.

Description

Technical Field

[0001] This invention relates to neural microelectrode technology in the field of biomedical engineering technology, specifically to a trans-interface deep-pore array neural electrode capable of storing conductive polymers and its fabrication process. Background Technology

[0002] Noble metals such as platinum (Pt) and platinum-iridium (PtIr) possess excellent biocompatibility and chemical inertness, and have been widely used in the fabrication of neural electrodes; however, their charge injection capabilities are limited. A common method to improve charge injection capability is to deposit a modified coating material on the electrode surface. Poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS), due to its excellent biocompatibility, chemical stability, and highly non-uniform surface morphology, can promote reversible Faraday charge injection, making it one of the best choices for modifying the interface of neural electrodes.

[0003] However, this coating material consistently faces challenges in terms of long-term reliability. Firstly, because the coating is typically adhered to the surface of a planar metal electrode, it is susceptible to cracking and even peeling due to its own volume contraction / expansion. Secondly, increasing the charge injection capability requires a certain thickness for the conductive polymer PEDOT:PSS coating, but increased thickness further deteriorates adhesion, increasing the likelihood of coating detachment. Therefore, the main problem to be solved in realizing the application of PEDOT:PSS in the interface modification of various neural electrodes is how to improve the interfacial adhesion and stability of the conductive polymer PEDOT:PSS coating while increasing the charge injection capability, and how to adapt to the effects of contraction, expansion, and deformation.

[0004] Surface roughening is a common method to improve the adhesion between PEDOT:PSS coatings and metal electrodes. A review of existing technologies revealed that in 2017, C Boehler et al. published an article in ACS Applied Materials Interfaces, 2017, 9(1):189-197 entitled "Long-Term Stable Adhesion for Conducting Polymers in Biomedical Applications: IrOx and Nanostructured Platinum Solve the Chronic Challenge," which introduced two strategies to improve interfacial mechanical adhesion: providing rough surface textures with iridium oxide or nano-platinum as adhesion promoters to physically anchor the electroplated PEDOT:PSS coating. However, this method involves high processing costs and low efficiency in fabricating adhesion promoters, and it only addresses the issue of adhesion without effectively improving charge injection capabilities.

[0005] Compared to electroplating for PEDOT:PSS coating deposition, spin coating is more efficient and produces better coating uniformity, but its interfacial adhesion and conductivity are relatively poor, making it more prone to detachment and failure. In 2020, G Dijk et al. published an article in Advanced Materials Interfaces, 2020, 7(16), 2000675 entitled "Influence of PEDOT:PSSCoating Thickness on the Performance of Stimulation Electrodes," pointing out that the stimulation performance of the electrode depends on the coating thickness. They studied the effect of coating thickness on impedance, charge injection, and electrode stability after multilayer spin-coating of PEDOT:PSS coatings, indicating that thicker electrode coatings can withstand more pulses and higher voltages, but are also more prone to cracking, delamination, and detachment. This study did not provide methods to solve the problems of cracking and detachment when the coating is thickened.

[0006] In 2024, YU Cho et al. published an article in Advanced Functional Materials, 2024, 34(6):2310908 entitled "MRI-Compatible, Transparent PEDOT:PSS Neural Implants for the Alleviation of Neuropathic Pain with Motor Cortex Stimulation". They selected a flexible PET substrate roughened by oxygen plasma and directly spin-coated and peeled off PEDOT:PSS as a conductive layer, giving the cortical neural electrode MRI-compatible and optically transparent properties. Simultaneously, immersing PEDOT in a heated ethylene glycol solution significantly reduced electrochemical impedance and improved stimulation performance compared to electrodes treated with ethylene glycol at room temperature. However, this study only characterized the stability of electrode impedance after repeated bending, primarily a mechanical evaluation of the lead wire portion, without characterizing the electrical stimulation stability of the exposed PEDOT:PSS electrode points. Furthermore, the PEDOT:PSS coating prepared in this paper was a single planar coating, without addressing methods to solve the problems of interface delamination and detachment risks. Summary of the Invention

[0007] The technical problem to be solved:

[0008] As mentioned earlier, in the existing technology for preparing PEDOT:PSS coatings on planar electrode sites, the main research direction is to improve the interfacial properties of the planar electrodes through physical or chemical methods. However, this approach cannot effectively solve the problems of cracking, delamination, and peeling of PEDOT:PSS coatings. Moreover, in order to further improve electrochemical performance and enhance charge injection capability, the current main approach is to increase the coating thickness by increasing the electroplating time or spin coating cycles. However, the resulting thicker coating will further deteriorate the coating's adhesion and stability, making it more prone to cracking, delamination, and peeling.

[0009] To address the aforementioned problems, this invention proposes a trans-interface deep-pore array neural electrode capable of storing conductive polymers, and outlines a corresponding preparation method. The neural electrode proposed in this invention possesses a "reservoir" structure composed of a trans-interface deep-pore array, effectively increasing the electrode's specific surface area. Simultaneously, the dispersion of PEDOT:PSS within independent micropores reduces the impact of localized coating detachment on the overall electrode performance, exhibiting extremely high resistance to detachment and facilitating long-term, reliable neural signal acquisition and electrical stimulation.

[0010] The technical solution of this invention is as follows:

[0011] A trans-interface deep-hole array neural electrode capable of storing conductive polymer includes a base layer, a conductive layer, a top encapsulation layer, and a conductive polymer PEDOT:PSS coating; wherein the base layer, conductive layer, and top encapsulation layer are arranged from bottom to top.

[0012] The conductive layer includes pads, wires, and electrode points; and the electrode points and pads are exposed through windows in the top encapsulation layer.

[0013] The exposed surface of the electrode points is provided with an array of cross-interface deep holes, which penetrate the conductive layer and form blind holes in the substrate layer.

[0014] The conductive polymer PEDOT:PSS coating fills the deep hole array of the electrode points and covers the exposed surface of the electrode points.

[0015] Preferably, the deep hole has a large inner opening and a small outer opening structure, wherein the diameter of the blind hole formed in the base layer is larger than the diameter of the hole located in the platinum-iridium alloy conductive layer.

[0016] Preferably, it further includes a nano-adhesive layer, which is located between the conductive polymer PEDOT:PSS coating, the platinum-iridium alloy conductive layer, and the substrate layer.

[0017] Preferably, the conductive layer is made of platinum-iridium alloy sheet, platinum sheet, or stainless steel sheet.

[0018] Preferably, the base layer and the top encapsulation layer are made of non-conductive elastic materials, including but not limited to polydimethylsiloxane, polyurethane, styrene-ethylene-butene-styrene tetromer, and medical-grade silicone rubber.

[0019] Preferably, the thickness of the substrate layer is 100-2000 micrometers, the thickness of the top encapsulation layer is 20-500 micrometers, the thickness of the conductive layer is 10-30 micrometers, the diameter of the electrode point is 100-3000 micrometers, the diameter of the deep hole is 10-30 micrometers, and the depth of the blind hole formed in the substrate layer is 20-200 micrometers.

[0020] A method for fabricating a trans-interface deep-pore array neural electrode capable of storing conductive polymers includes the following steps:

[0021] Step 1: Lay the metal conductive sheet corresponding to the conductive layer flat and fix it on the carrier, spin-coat the surface of the metal conductive sheet with liquid base material, and form the base layer after curing;

[0022] Step 2: Flip and peel off the carrier to expose the metal conductive sheet facing outwards. Cut the metal conductive sheet with a femtosecond laser and peel off the non-electrode areas to form a conductive layer.

[0023] Step 3: Spin-coat liquid encapsulation material onto the surface of the conductive layer, and allow it to cure to form the top encapsulation layer;

[0024] Step 4: The base layer and top encapsulation layer are cut with a femtosecond laser to form the outer contour of the neural electrode, and the surface encapsulation material of the conductive layer electrode point area is removed in situ by femtosecond laser scanning to expose the electrode point;

[0025] Step 5: Create a cross-interface deep hole array on the electrode point surface using a femtosecond laser. The deep holes penetrate the conductive layer and form blind holes in the substrate layer.

[0026] Step 6: Using a patterned mask, the electrode is adsorbed onto the surface of the neural electrode, exposing only the conductive layer electrode area. After spin-coating with PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating is formed that fills the deep hole array across the interface and coats the electrode surface, thus completing the electrode processing.

[0027] Preferably, in step 6, before spin-coating the PEDOT:PSS solution, a layer of hydrophilic polyurethane is first coated to form a nano-adhesive layer. After spin-coating the PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating is formed, completing the electrode processing. In this way, after spin-coating PEDOT:PSS, an interpenetrating polymer molecular network is formed in the aqueous system, achieving stronger interfacial adhesion.

[0028] A method for fabricating a trans-interface deep-pore array neural electrode capable of storing conductive polymers includes the following steps:

[0029] Step 1: Lay the metal conductive sheet corresponding to the conductive layer flat and fix it on the carrier, spin-coat the surface of the metal conductive sheet with liquid base material, and form the first base layer after curing;

[0030] Step 2: Form a first micropore array with an aperture of R1 on the first substrate layer using a femtosecond laser; the first micropore array only penetrates the first substrate layer;

[0031] Step 3: Spin-coat a removable filler onto the surface of the first substrate layer to fill the first micropore array and cover the surface of the first substrate layer;

[0032] Step 4: Remove the removable filler from the surface of the first substrate layer to expose the surface of the first substrate layer, while the first micropore array is still filled with the removable filler;

[0033] Step 5: Spin-coat the first base layer surface with liquid base material again, and form a second base layer after curing;

[0034] Step 6: Flip and peel off the carrier so that the metal conductive sheet faces outward. Cut the metal conductive sheet with a femtosecond laser and peel off the non-electrode area to form a conductive layer.

[0035] Step 7: Spin-coat liquid encapsulation material onto the surface of the conductive layer, and allow it to cure to form the top encapsulation layer;

[0036] Step 8: The base layer and top encapsulation layer are cut using a femtosecond laser to form the outer contour of the neural electrode. The surface encapsulation material of the conductive layer electrode point area is removed in situ using a femtosecond laser to expose the electrode point. Then, a second micro-hole array with a aperture of R2 is created on the surface of the electrode point using a femtosecond laser. The second micro-hole array penetrates the conductive layer, and the micro-holes in the second micro-hole array overlap with the micro-holes in the first micro-hole array below, exposing the filler in the first micro-hole array below. And R1>R2.

[0037] Step 9: After removing the filler in the first micropore array and cleaning and drying, a deep hole array with a larger reserve space is formed in the conductive layer and the first substrate layer.

[0038] Step 10: Using a patterned mask, the electrode is adsorbed onto the surface of the neural electrode, exposing only the conductive layer electrode area. After spin-coating with PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating that fills the deep hole array and coats the electrode surface is formed, thus completing the electrode processing.

[0039] Preferably, the removable filler is photoresist; in step 4, the photoresist on the surface of the first substrate layer is removed by an oxygen plasma device; in step 9, the photoresist in the first micro-hole array is removed by immersion in an organic solvent.

[0040] Beneficial effects

[0041] The trans-interface deep-pore array neural electrode capable of storing conductive polymer and its preparation method proposed in this invention have the following advantages:

[0042] 1. The electrode has a deep hole array that penetrates the conductive layer, and PEDOT:PSS modified material is stored in the substrate in the depth direction, which can effectively improve the specific surface area of ​​the electrode.

[0043] 2. The electrode is designed with an independent deep hole array structure, which greatly reduces the impact of partial or complete peeling of coating material on the top surface of the electrode point and inside the deep holes. The overall failure risk is distributed through a large number of deep holes, which can ensure excellent charge storage, especially charge injection capability, for a long time.

[0044] 3. The neural electrode fabrication method proposed in this invention is based on spin coating combined with femtosecond laser. The electrode fabrication process is simple, efficient and low cost. It only requires a femtosecond laser to complete key steps such as conductive layer patterning, flexible substrate and encapsulation layer contour cutting, electrode point exposure and conductive layer penetration, and substrate layer blind hole formation.

[0045] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0046] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0047] Figure 1 This is a schematic diagram of the cross-sectional structure and failure modes of a trans-interface deep-pore array neural electrode site capable of storing conductive polymer, provided in Embodiment 1 of the present invention.

[0048] Figure 2 A top view of the overall structure and a single site of a trans-interface deep-pore array neural electrode capable of storing conductive polymer provided in Embodiment 1 of the present invention;

[0049] Figure 3 This is a process flow diagram of a trans-interface deep-pore array neural electrode capable of storing conductive polymer, provided in Embodiment 1 of the present invention.

[0050] Figure 4 A flowchart illustrating the electrode fabrication process with a larger conductive polymer storage space, which is different from that in Example 1, provided in Embodiment 2 of the present invention.

[0051] Figure 5 This is a schematic diagram of the cross-sectional structure of the electrode site with a hydrophilic polyurethane adhesive layer, which is different from that in Embodiment 1, provided in Embodiment 3 of the present invention.

[0052] The markings in the figure represent: 1. Bottom silicone substrate layer, 2. Platinum-iridium alloy conductive layer, 3. Top silicone encapsulation layer, 4. Conductive polymer PEDOT:PSS coating, 5. Double silicone substrate, 6. Platinum-iridium alloy electrode point, 7. Top surface of electrode point, 8. Deep hole array. Detailed Implementation

[0053] The following embodiments provide a trans-interface deep-hole array neural electrode capable of storing conductive polymer and its preparation method, which can effectively solve the long-standing problem of insufficient interfacial adhesion of spin-coated PEDOT:PSS coatings. It is not only not easy to fall off, but also not afraid of falling off. It makes full use of the "silicone-platinum-iridium alloy" trans-interface laser femtosecond rapid processing to form a deep-hole array. The independent deep-hole array will form a reservoir-like storage structure, which distributes the risk of falling off. It can effectively ensure that the conductive polymer PEDOT:PSS, as an interface modification material, can provide high charge storage capacity and high charge injection capacity for a long time.

[0054] Example 1:

[0055] like Figure 1 and Figure 2 As shown, the trans-interface deep-pore array neural electrode capable of storing conductive polymer proposed in this embodiment includes a bottom silicone substrate layer 1, a platinum-iridium alloy conductive layer 2, a top silicone encapsulation layer 3, and a conductive polymer PEDOT:PSS coating 4; wherein, from bottom to top, the layers are: bottom silicone substrate layer 1, platinum-iridium alloy conductive layer 2, and top silicone encapsulation layer 3. It should be noted that, in addition to the platinum-iridium alloy conductive layer, the conductive layer can also be a platinum conductive layer or a stainless steel conductive layer. The substrate layer and encapsulation layer use biocompatible silicone materials, such as polydimethylsiloxane (PDMS), polyurethane (PU), and styrene-ethylene-butene-styrene tetroxide (SEBS).

[0056] The platinum-iridium alloy conductive layer 2 includes pads, wires, and electrode points; and the electrode points and pads are exposed through windows in the top encapsulation layer.

[0057] The exposed surface of the electrode point 6 is provided with a cross-interface deep hole array 8, which penetrates the platinum-iridium alloy conductive layer 2 and forms blind holes in the bottom silicone substrate layer 1.

[0058] The conductive polymer PEDOT:PSS coating 4 fills the deep hole array 8 of the electrode points and covers the exposed surface of the electrode points.

[0059] Figure 1 In addition to providing the cross-sectional structure of the neural electrode sites in the cross-interface deep-hole array, failure modes are also given: such as Figure 1 (a)-(c) include three typical failure modes: first, partial detachment of the coating on the top surface and within the micropores; second, complete detachment of the top surface coating; and third, complete detachment of the coating within some micropores, leaving coating material still present in the remaining micropores. Regardless of the mode, the failure risk at the electrode modification interface can be distributed through a large number of deep holes, ensuring excellent charge storage, especially charge injection capability, over time. Furthermore, the fabrication of deep-hole arrays across the "silicone-platinum-iridium" interface offers significant advantages over simply roughening the surface of the platinum-iridium alloy electrode points. The PEDOT:PSS modified material, stored within the blind holes of the bottom silicone substrate layer, which acts like a "reservoir," further increases the specific surface area of ​​the modified material in the region penetrating the platinum-iridium alloy conductive layer. Simultaneously, the deep-hole array structure provides a more robust anchoring capability for the modified material.

[0060] Figure 2 A cross-interface deep-pore array neural electrode structure capable of storing conductive polymers is presented. This structure features four-channel platinum-iridium alloy electrode points 6 arranged on a bilayer silicone substrate 5, which can be used for cortical EEG acquisition and stimulation modulation. This structural design can be flexibly adjusted according to the specific needs of the applicable subjects and the size of the target neural tissue. A deep-pore array 8 is uniformly distributed on the top surface 7 of the electrode points. The aperture, spacing, and depth of the deep-pore array can also be customized according to specific needs, requiring only simple adjustments to the laser processing parameters.

[0061] Figure 3 The method for fabricating the trans-interface deep-pore array neural electrode capable of storing conductive polymers in this embodiment is provided:

[0062] Figure 3 (a): A 25-micron thick platinum-iridium alloy sheet is laid flat and fixed on a 4-inch glass slide (carrier). Liquid silicone (MED-4244, Nusil, USA) is spin-coated at 750 rpm for 30 seconds. The mixture is then heated in a 150-degree Celsius oven for 1 hour. The spin-coating and heating-and-baking steps are repeated once to form a bottom silicone base layer with a total cured thickness of 800 microns.

[0063] Figure 3 (b): Flip the platinum-iridium alloy sheet so that it faces upwards, use a femtosecond laser (wavelength 1030nm, AMT-MDM-6 ultrafast laser planar system, Inno Laser, China) to cut the platinum-iridium alloy sheet, and use fine tweezers to manually peel off the non-electrode wiring area to form a platinum-iridium alloy conductive layer.

[0064] Figure 3 (c): A layer of liquid silicone (MED-4244, Nusil, USA) is spin-coated onto the surface of the platinum-iridium alloy conductive layer at 3000 rpm for 30 seconds, and then heated in an oven at 150 degrees Celsius for 1 hour to form a top silicone encapsulation layer with a curing thickness of 100 micrometers.

[0065] Figure 3 (d): The outer contour of the neural electrode is formed by cutting the bottom silicone substrate layer and the top silicone encapsulation layer with a femtosecond laser. At the same time, the silicone on the surface of the platinum-iridium alloy electrode point is removed in situ by laser scanning, so that the electrode point is fully exposed. The diameter of the platinum-iridium alloy electrode point is 3000 micrometers.

[0066] Figure 3 (e): Continue to use femtosecond laser to create an array of cross-interface deep holes on the surface of the platinum-iridium alloy electrode points. The diameter of each deep hole is 30 micrometers, penetrating the platinum-iridium alloy conductive layer, and further forming blind holes with a depth of 100 micrometers in the underlying silicone substrate layer.

[0067] Figure 3 (f): Using a patterned PET film as a mask, the electrode is aligned and attached to the surface of the neural electrode by electrostatic adsorption, exposing only the platinum-iridium alloy electrode points. PEDOT:PSS solution (PH1000, Heraeus Clevios, Germany) is spin-coated at 600 rpm for 30 seconds, followed by hot plate baking at 110 degrees Celsius for 10 minutes. The PET mask is then removed, forming a conductive polymer PEDOT:PSS coating that fills the deep hole array and coats the top surface of the electrode points.

[0068] Example 2:

[0069] In this embodiment, the deep holes in the trans-interface deep-pore array neural electrode capable of storing conductive polymers have a larger inner diameter and smaller opening structure compared to Embodiment 1. The diameter of the blind holes formed in the substrate layer is larger than the diameter of the holes located in the platinum-iridium alloy conductive layer. This not only increases the storage space volume of the PEDOT:PSS modified material, thereby improving the charge storage and charge injection capabilities, but also increases the contact area between the PEDOT:PSS coating filled in the large-diameter micropore array and the platinum-iridium alloy conductive layer, further increasing the interfacial bonding force and ensuring that the PEDOT:PSS coating is not easy to fall off and is not afraid of falling off.

[0070] To achieve a large opening and small structure within a deep hole, such as Figure 4 As shown, the specific process steps are as follows:

[0071] Figure 4 (a): A 25-micron thick platinum-iridium alloy sheet is laid flat and fixed on a 4-inch glass slide. Liquid silicone (MED-4244, Nusil, USA) is spin-coated at 750 rpm for 30 seconds. The sheet is then heated in a 150-degree Celsius oven for 1 hour to form a first bottom silicone base layer with a cured thickness of 400 microns.

[0072] Figure 4(b): The first layer of the bottom silicone substrate was cut using a femtosecond laser (wavelength 1030nm, AMT-MDM-6 ultrafast laser planar system, Inno Laser, China) to form a first micropore array with a pore size of 100 micrometers.

[0073] Figure 4 (c): Spin-coat a layer of positive photoresist to fill the first micropore array and cover the surface of the first bottom silicone substrate layer;

[0074] Figure 4 (d): The device obtained in the previous step is placed in an oxygen plasma device for light photoresist removal, ensuring that the first bottom silicone substrate layer is just exposed, while the first micropore array is still filled with photoresist.

[0075] Figure 4 (e): Spin coat liquid silicone (MED-4244, Nusil, USA) again at 750 rpm for 30 seconds, then heat in an oven at 150 degrees Celsius for 1 hour to form a second bottom silicone base layer with a curing thickness of 400 micrometers.

[0076] Figure 4 (f): Flip the platinum-iridium alloy sheet so that it faces upward, cut the platinum-iridium alloy sheet with a femtosecond laser, and manually peel off the non-electrode wiring area with fine tweezers to form a platinum-iridium alloy conductive layer.

[0077] Figure 4 (g): Spin-coat a layer of liquid silicone (MED-4244, Nusil, USA) onto the surface of the platinum-iridium alloy conductive layer at 3000 rpm for 30 seconds, and heat in an oven at 150 degrees Celsius for 1 hour to form a top silicone encapsulation layer with a curing thickness of 100 micrometers.

[0078] Figure 4 (h): A femtosecond laser cuts a double-layer silicone substrate and a top silicone encapsulation layer to form the outer contour of the neural electrode. At the same time, the laser scans and removes the silicone on the surface of the platinum-iridium alloy electrode points in situ, so that the electrode points are fully exposed. The diameter of the platinum-iridium alloy electrode points is 3000 micrometers. The femtosecond laser is then used to create a second micro-hole array with a diameter of 30 micrometers on the surface of the platinum-iridium alloy electrode points, penetrating the platinum-iridium alloy conductive layer. Each microhole in the second micro-hole array corresponds to and overlaps with each microhole in the first micro-hole array below, exposing the photoresist in the first micro-hole array below. The more concentric the microholes are, the better the effect.

[0079] Figure 4 (i): Immerse the device obtained in the previous step in acetone solution to remove the photoresist, clean it with deionized water and dry it with nitrogen gas to form a deep hole array with a larger storage space in the silicone.

[0080] Figure 4(j): Using a patterned PET film as a mask, it is aligned and attached to the surface of the neural electrode by electrostatic adsorption, exposing only the platinum-iridium alloy electrode points. PEDOT:PSS solution (PH1000, Heraeus Clevios, Germany) is spin-coated at 600 rpm for 30 seconds, followed by baking on a hot plate at 110 degrees Celsius for 10 minutes. The PET mask is then removed, forming a conductive polymer PEDOT:PSS coating that fills the deep hole array with a "small opening and large belly" and coats the top surface of the electrode points.

[0081] Example 3:

[0082] The specific process steps in this embodiment differ from those in Embodiment 1 in that, before spin-coating PEDOT:PSS to fill the deep-pore array, a layer of hydrophilic polyurethane is first sprayed to form a nano-adhesive layer, and then PEDOT:PSS is spin-coated to fill the deep-pore array. This results in the formation of an interpenetrating polymer network in the aqueous system after spin-coating PEDOT:PSS, achieving stronger interfacial adhesion and effectively reducing phenomena such as cracking, delamination, and detachment of PEDOT:PSS. The structure is as follows: Figure 5 As shown, a more robust and adhesive conductive polymer PEDOT:PSS coating is obtained.

[0083] Of course, in Example 2, before spin-coating PEDOT:PSS to fill the deep hole array, a layer of hydrophilic polyurethane can be sprayed to form a nano-adhesive layer, and then PEDOT:PSS can be spin-coated to fill the deep hole array to obtain a more tough and adhesive conductive polymer PEDOT:PSS coating.

[0084] The long-term stability of strong adhesion of conductive polymer coatings is an important guarantee for the function and lifespan of various bioelectronic devices. The trans-interface deep-hole array neural electrode proposed in this invention can store conductive polymers. It introduces the conductive polymer PEDOT:PSS coating into the blind holes of the underlying silicone substrate, providing a new method to improve coating stability, charge storage and charge injection capabilities.

[0085] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A trans-interface deep-pore array neural electrode capable of storing conductive polymers, characterized in that: It includes a base layer, a conductive layer, a top encapsulation layer, and a conductive polymer PEDOT:PSS coating; from bottom to top, these are the base layer, the conductive layer, and the top encapsulation layer. The conductive layer includes pads, wires, and electrode points; and the electrode points and pads are exposed through windows in the top encapsulation layer. The exposed surface of the electrode points is provided with an array of cross-interface deep holes, which penetrate the conductive layer and form blind holes in the substrate layer. The conductive polymer PEDOT:PSS coating fills the deep hole array of the electrode points and covers the exposed surface of the electrode points.

2. The trans-interface deep-pore array neural electrode capable of storing conductive polymer according to claim 1, characterized in that: The deep hole has a large inner diameter and a small outer diameter, wherein the diameter of the blind hole formed in the base layer is larger than the diameter of the hole located in the platinum-iridium alloy conductive layer.

3. A trans-interface deep-pore array neural electrode capable of storing conductive polymer according to claim 1 or 2, characterized in that: It also includes a nano-adhesive layer, which is located between the conductive polymer PEDOT:PSS coating, the platinum-iridium alloy conductive layer, and the substrate layer.

4. The trans-interface deep-pore array neural electrode capable of storing conductive polymer according to claim 1, characterized in that: The conductive layer is made of platinum-iridium alloy sheet, platinum sheet, or stainless steel sheet.

5. The trans-interface deep-pore array neural electrode capable of storing conductive polymer according to claim 1, characterized in that: The base layer and the top encapsulation layer are made of non-conductive elastic materials, including but not limited to polydimethylsiloxane, polyurethane, styrene-ethylene-butene-styrene tetromer, and medical-grade silicone rubber.

6. The trans-interface deep-pore array neural electrode capable of storing conductive polymer according to claim 1, characterized in that: The thickness of the substrate layer is 100–2000 micrometers, the thickness of the top encapsulation layer is 20–500 micrometers, the thickness of the conductive layer is 10–30 micrometers, the diameter of the electrode point is 100–3000 micrometers, the diameter of the deep hole is 10–30 micrometers, and the depth of the blind hole formed in the substrate layer is 20–200 micrometers.

7. A method for preparing a trans-interface deep-pore array neural electrode capable of storing conductive polymer as described in claim 1, characterized in that: Includes the following steps: Step 1: Lay the metal conductive sheet corresponding to the conductive layer flat and fix it on the carrier, spin-coat the surface of the metal conductive sheet with liquid base material, and form the base layer after curing; Step 2: Flip and peel off the carrier so that the metal conductive sheet faces outward. Cut the metal conductive sheet with a femtosecond laser and peel off the non-electrode area to form a conductive layer. Step 3: Spin-coat liquid encapsulation material onto the surface of the conductive layer, and allow it to cure to form the top encapsulation layer; Step 4: The base layer and top encapsulation layer are cut with a femtosecond laser to form the outer contour of the neural electrode, and the surface encapsulation material of the conductive layer electrode point area is removed in situ by femtosecond laser scanning to expose the electrode point; Step 5: A cross-interface deep hole array is formed on the surface of the electrode point using a femtosecond laser. The deep holes penetrate the conductive layer and form blind holes in the substrate layer. Step 6: Using a patterned mask, the electrode is adsorbed onto the surface of the neural electrode, exposing only the conductive layer electrode area. After spin-coating with PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating is formed that fills the deep hole array across the interface and coats the electrode surface, thus completing the electrode processing.

8. The method according to claim 7, characterized in that: In step 6, before spin-coating the PEDOT:PSS solution, a layer of hydrophilic polyurethane is first coated to form a nano-adhesive layer. After spin-coating the PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating is formed, completing the electrode processing. In this way, after spin-coating PEDOT:PSS, an interpenetrating network of polymer molecules is formed in the aqueous system, achieving stronger interfacial adhesion.

9. A method for preparing a trans-interface deep-pore array neural electrode capable of storing conductive polymer as described in claim 2, characterized in that: Includes the following steps: Step 1: Lay the metal conductive sheet corresponding to the conductive layer flat and fix it on the carrier, spin-coat the surface of the metal conductive sheet with liquid base material, and form the first base layer after curing; Step 2: Form a first micropore array with an aperture of R1 on the first substrate layer using a femtosecond laser; the first micropore array only penetrates the first substrate layer; Step 3: Spin-coat a removable filler onto the surface of the first substrate layer to fill the first micropore array and cover the surface of the first substrate layer; Step 4: Remove the removable filler from the surface of the first substrate layer to expose the surface of the first substrate layer, while the first micropore array is still filled with the removable filler; Step 5: Spin-coat the first base layer surface with liquid base material again, and form a second base layer after curing; Step 6: Flip and peel off the carrier so that the metal conductive sheet faces outward. Cut the metal conductive sheet with a femtosecond laser and peel off the non-electrode area to form a conductive layer. Step 7: Spin-coat liquid encapsulation material onto the surface of the conductive layer, and allow it to cure to form the top encapsulation layer; Step 8: The base layer and top encapsulation layer are cut with a femtosecond laser to form the outer contour of the neural electrode, and the surface encapsulation material of the conductive layer electrode point area is removed in situ by femtosecond laser scanning to expose the electrode point; A second micropore array with a aperture of R2 is then created on the surface of the electrode point using a femtosecond laser. The second micropore array penetrates the conductive layer, and the micropores in the second micropore array overlap with the micropores in the first micropore array below, exposing the filler in the first micropore array below. R1>R2. Step 9: After removing the filler in the first micropore array and cleaning and drying, a deep hole array with a larger reserve space is formed in the conductive layer and the first substrate layer. Step 10: Using a patterned mask, the electrode is adsorbed onto the surface of the neural electrode, exposing only the conductive layer electrode area. After spin-coating with PEDOT:PSS solution and drying, a conductive polymer PEDOT:PSS coating that fills the deep hole array and coats the electrode surface is formed, thus completing the electrode processing.

10. The method according to claim 9, characterized in that: The removable filler is photoresist; in step 4, the photoresist on the surface of the first substrate layer is removed by an oxygen plasma device; in step 9, the photoresist in the first micro-hole array is removed by immersion in an organic solvent.

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