A Micro-top-hat Stereo-contact Platinum-Iridium Cortical Microelectrode and Its Preparation Method

Abstract

The present invention discloses a micro-top-hat three-dimensional contact platinum-iridium cortical microelectrode and a preparation method thereof, which includes a bottom silicone substrate, a platinum-iridium alloy micro-top-hat, a platinum-iridium alloy wire, and a top silicone substrate; the bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate are all in a circular straw hat shape, and from bottom to top are the bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate, and the three are buckled together. The preparation method includes: (1) pasting a water-soluble tape on the surface of a platinum-iridium alloy sheet; (2) stamping to form a platinum-iridium alloy micro-top-hat; (3) laser processing to form a platinum-iridium alloy wire; (4) submerging the platinum-iridium alloy wire together with the platinum-iridium alloy micro-top-hat into semi-solid silicone, and after curing, forming a bottom silicone substrate; (5) spin-coating liquid silicone, and after the liquid silicone is heated and cured, forming a top silicone substrate. The present invention has very important practical value for improving the long-term in-vivo signal quality, electrode reliability and safety of cortical microelectrodes.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical electrotechnology, and particularly relates to a cortical microelectrode and a preparation method thereof. Background Art

[0002] As a brain-computer interface device, a neural microelectrode is an important physical basis for directly reading neuron signals and precisely regulating nerve activities. In order to more accurately analyze the laws of brain nerve activities and improve the recording quality, it is necessary for the recording electrode to collect signals with a higher signal-to-noise ratio. Among them, cortical microelectrodes, as a very important type, often use flexible materials as the substrate of cortical microelectrodes to ensure their fitting degree with the surface of the cerebral cortex. However, most of the existing cortical microelectrode contacts have a planar structure and cannot achieve gapless contact with the surface of the cerebral cortex, which may have a certain impact on the signal acquisition quality. Therefore, developing cortical microelectrodes with a micro-top hat three-dimensional structure is of great significance for obtaining higher-quality electroencephalogram signals. In addition, most of the current cortical microelectrodes are prepared on a polymer film substrate through the MEMS process. If a low-cost and high-efficiency laser processing process is used, the cutting process is likely to cause ablation and contamination of the silicone substrate. Therefore, it is necessary to change the existing laser processing process of directly cutting metal on the silicone surface to effectively reduce the ablation risk and residue contamination of the silicone substrate.

[0003] After searching the prior art, it is found that Schuettler M et al. from University College London, UK, wrote an article "Fabrication of implantable microelectrode arrays by laser cutting of silicone rubber and platinum foil" in Journal of neural engineering, 2005, 2(1): S121. The metal foil was placed on the silicone surface and manually pressed with a pressure of 100 kPa. The upper and lower layers of silicone of the metal foil were both formed by spin coating and curing. The patterning of the metal layer and the formation of the electrode outer contour were achieved through laser cutting. However, this method is prone to over-cutting and damaging the silicone substrate during the laser cutting process, and it is difficult to clean the metal residues remaining on the silicone substrate. Moreover, the electrode points are concave, resulting in gaps when the electrode points contact the cortical tissue.

[0004] Rui Yuefeng et al. from Shanghai Jiao Tong University published an article titled "Parylene-based implantable Pt-black coated flexible 3-D hemispherical microelectrode arrays for improved neural interfaces" in Microsystem technologies, 2011, 17(3): 437-442. Photoresist was spin-coated on the chromium surface, and the chromium was etched wetly to form a hemispherical pattern. After baking the photoresist to form a hemispherical shape, a hollow micro-top-hat electrode structure was gradually formed by depositing the first parylene insulating layer, sputtering gold, and depositing the second parylene insulating layer. However, this method affects the height of the micro-top-hat by the thickness of the spin-coated photoresist, limiting the height of the micro-top-hat within dozens of micrometers. At the same time, the hollow micro-top-hat electrode structure makes it easy to produce a crushing problem when the electrode contacts the cortical tissue.

[0005] CN113041492A discloses an electrode contact piece for balancing charges and its manufacturing method. The electrode contact piece body generates a concave part, a convex part, and a skirt through the die closing of a concave-convex die. A rough convex surface is formed by using a surface treatment process to increase the contact area. Then, the skirt of the electrode contact piece is joined to the wire through a welding technique. The macro electrode top hat has a large size and is easy to stamp and form. However, the electrode points and wires of the microelectrode are small in size and thin in thickness, and it is easy to cause damage at the wire during the stamping and forming process, and it is difficult to join the electrode points and wires through the welding technique. Therefore, this manufacturing method is more suitable for the manufacturing of macro electrodes.

[0006] CN110251125 A discloses a flexible and stretchable neural electrode and its preparation method and application, including a flexible substrate, a detection electrode array, and an insulating layer. A plurality of protruding micron pillar clusters are arranged on the surface of the flexible substrate, and then metal is evaporated on the surface of the protruding micron pillar clusters to form detection sites with an uneven three-dimensional structure, which can increase the contact area between the device and the tissue and achieve the effect of improving the signal quality. However, the Young's moduli of common conductive metal materials and silica gel differ by several orders of magnitude. Therefore, the metal evaporation process cannot be used for flexible electrodes with silica gel substrates.

[0007] Therefore, it is of great practical value to develop a micro-top-hat three-dimensional contact platinum-iridium cortical microelectrode and its preparation method to improve the recording signal quality of cortical microelectrodes, which can effectively solve the problem that there is a gap when the concave microelectrode points of the current cortical microelectrodes are always in contact with the cortical tissue, and at the same time avoid laser cutting of metal wires on the silica gel substrate to ensure cleanliness and no damage on the silica gel substrate. Summary of the Invention

[0008] To overcome the deficiencies of the prior art, the present invention provides a micro-top-hat three-dimensional contact platinum-iridium cortical microelectrode and a preparation method thereof, including a bottom silicone substrate, a platinum-iridium alloy micro-top-hat, a platinum-iridium alloy wire, and a top silicone substrate; the bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate are all in the shape of a round straw hat, and from bottom to top are the bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate, and the three are buckled together. The preparation method includes: (1) sticking a water-soluble tape on the surface of a platinum-iridium alloy sheet; (2) stamping to form a platinum-iridium alloy micro-top-hat; (3) laser processing to form a platinum-iridium alloy wire; (4) submerging the platinum-iridium alloy wire together with the platinum-iridium alloy micro-top-hat into semi-solid silicone, and after curing, forming a bottom silicone substrate; (5) spin-coating liquid silicone, and after the liquid silicone is heated and cured, forming a top silicone substrate. The present invention has very important practical value for improving the long-term in-vivo signal quality, electrode reliability, and safety of cortical microelectrodes.

[0009] The technical solution adopted by the present invention to solve its technical problems includes the following steps:

[0010] A micro-top-hat three-dimensional contact platinum-iridium cortical microelectrode includes a bottom silicone substrate, a platinum-iridium alloy micro-top-hat, a platinum-iridium alloy wire, and a top silicone substrate;

[0011] The bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate are all in the shape of a round straw hat, and from bottom to top are the bottom silicone substrate, the platinum-iridium alloy micro-top-hat, and the top silicone substrate, and the three are buckled together;

[0012] A plurality of laser micropores are provided in a circle on the brim of the platinum-iridium alloy micro-top-hat; the upper surface of the platinum-iridium alloy micro-top-hat is a microelectrode contact;

[0013] One end of the platinum-iridium alloy wire is connected to the brim of the platinum-iridium alloy micro-top-hat, and the other end extends out of the bottom silicone substrate and the top silicone substrate for connection with an external device;

[0014] The top of the top silicone substrate is hollowed out, and the microelectrode contact is flush with the upper surface of the top silicone substrate.

[0015] Further, both the bottom silicone substrate and the top silicone substrate are made of an elastomeric material.

[0016] Further, the elastomeric material is polydimethylsiloxane PDMS or polyurethane PU or platinum-catalyzed silicone rubber.

[0017] Further, the materials of the platinum-iridium alloy micro-top-hat and the platinum-iridium alloy wire are platinum-iridium alloy or platinum or gold.

[0018] Further, the height of the platinum-iridium alloy micro-top-hat is 100 - 500 microns.

[0019] Further, the diameter of the microelectrode contact is 50 to 200 micrometers.

[0020] A method for preparing a platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact includes the following steps:

[0021] Step 1: Paste a water-soluble tape on the surface of the platinum-iridium alloy sheet.

[0022] Step 2: Use the punch of the stamping die to punch from the platinum-iridium alloy sheet to the side of the water-soluble tape, and place the die at the corresponding position on the side of the water-soluble tape to form the cap of the platinum-iridium alloy micro-top hat by stamping.

[0023] Step 3: Fix the platinum-iridium alloy sheet adhered to the water-soluble tape on the carrier with tape, and use laser cutting to form the brim of the platinum-iridium alloy micro-top hat, the platinum-iridium alloy wire, and the laser micropores on the brim; peel off the non-retained area of the platinum-iridium alloy sheet, and the remaining retained area is the platinum-iridium alloy wire and the platinum-iridium alloy micro-top hat.

[0024] Step 4: Heat the semi-solid silicone, press the platinum-iridium alloy wire downward from the side of the water-soluble tape so that the platinum-iridium alloy wire is immersed in the semi-solid silicone. After the semi-solid silicone forms a film on the surface of the platinum-iridium alloy, lower the heating temperature so that the surface of the silicone presents a non-flowing viscous deformable state, and then apply pressure to the platinum-iridium alloy micro-top hat from the side of the water-soluble tape until the semi-solid silicone completely fills the internal space of the cap of the platinum-iridium alloy micro-top hat. After the semi-solid silicone cures, form the bottom silicone substrate.

[0025] Step 5: Dissolve the water-soluble tape with hot water.

[0026] Step 6: Attach a fan-shaped polymer film to the tail end of the platinum-iridium alloy wire as a temporary shield, spin-coat liquid silicone on the area where the platinum-iridium alloy wire and the platinum-iridium alloy micro-top hat are located, and then tear off the fan-shaped polymer film to expose the welding area at the tail end of the platinum-iridium alloy wire. After the liquid silicone is heated and cured, form the top silicone substrate.

[0027] Step 7: Use the laser cutting process to cut through the two layers of silicone substrates to form the microelectrode outer contour, and cut off the top area of the top silicone substrate to form a hollow, so that the upper surface of the top silicone substrate is flush with the microelectrode contact of the platinum-iridium alloy micro-top hat.

[0028] Step 8: Peel off the non-retained silicone outside the microelectrode outer contour to release the electrode.

[0029] Further, steps 2 and 3 are replaced with the following steps:

[0030] Use laser cutting to form a toothed contour on the platinum-iridium alloy sheet, then perform stamping to form the platinum-iridium alloy micro-top hat, and finally use the laser cutting process to obtain the platinum-iridium alloy wire connected to the platinum-iridium alloy micro-top hat.

[0031] Further, step 4 is replaced with:

[0032] The bottom silicone substrate is formed by in-situ spin coating: Place the platinum-iridium alloy sheet with one side facing up, attach a fan-shaped polymer film to the end of the platinum-iridium alloy wire, spin coat liquid silicone, then tear off the fan-shaped polymer film to expose the welding area at the end of the platinum-iridium alloy wire. After the silicone cures, the bottom silicone substrate is formed; during the spin coating process, the liquid silicone self-levels to fill the concave area of the platinum-iridium alloy micro-top cap, resulting in a flat bottom silicone substrate.

[0033] Further, the thickness of the platinum-iridium alloy sheet is 15 - 100 microns, the width of the platinum-iridium alloy wire is 30 - 500 microns, the diameter of the laser micro-holes is 20 - 200 microns, and the thicknesses of both the bottom silicone substrate and the top silicone substrate are 20 - 500 microns.

[0034] The beneficial effects of the present invention are as follows:

[0035] 1. Improve signal quality. By forming a micro-top cap three-dimensional structure through a stamping process, when laser cutting the top silicone substrate, the top silicone substrate at the micro-top cap three-dimensional structure is flush with the microelectrode contact point, enabling gapless contact between the microelectrode contact point and the cortical tissue, improving the signal-to-noise ratio, and thus achieving the purpose of improving the signal quality of cortical microelectrode recordings.

[0036] 2. Avoid silicone damage. To avoid laser cutting metal wires on the silicone substrate and ensure the flatness of the silicone substrate, first, the platinum-iridium alloy sheet and the water-soluble tape adhesive are stamped to form a platinum-iridium alloy micro-top cap, then the platinum-iridium alloy sheet is laser cut to pattern it, and then the bottom silicone substrate is formed by the method of micro-pressure immersion into semi-solid silicone or in-situ spin coating. The pre-positioned laser cutting process avoids over-cutting damage to the silicone substrate.

[0037] 3. Eliminate residue contamination. Laser cutting is performed first and then the bottom silicone substrate is filled. The laser patterning process of the platinum-iridium alloy sheet is on the water-soluble tape, rather than on the bottom silicone substrate, which can avoid metal residues and their oxides from adhering to the bottom silicone substrate and being difficult to remove. Description of the Drawings

[0038] Figure 1 It is a schematic diagram of the overall structure of the microelectrode of the present invention.

[0039] Figure 2 It is an exploded view of the microelectrode structure of the present invention.

[0040] Figure 3 It is a schematic diagram of the preparation process flow of the microelectrode of the present invention.

[0041] Figure 4Schematic process flow diagram of the micro-top hat and serpentine wire forming based on the tooth profile according to the second embodiment of the present invention.

[0042] Figure 5 Schematic process flow diagram of the third embodiment of the present invention.

[0043] Reference numerals: three-dimensional structure of the micro-top hat 1, microelectrode contact 2, silicone substrate 3, platinum-iridium alloy wire 4, bottom silicone substrate 5, platinum-iridium alloy micro-top hat 6, top silicone substrate 7, laser micropores 8, platinum-iridium alloy sheet adhered to the water-soluble tape 9, tooth profile 10, laser cutting machine 11, and stamping die 12. Detailed implementation manners

[0044] The present invention will be further described below with reference to the drawings and embodiments.

[0045] Most of the existing cortical electrodes adopt a planar structure. Only the macroelectrodes of the commercial cortical electrodes have a top hat structure. Moreover, the silicone material encapsulation layer is thicker than the polymer film material encapsulation layer. The microelectrode contacts are concave, and there are gaps when contacting the cortical tissue. In addition, the patterning of the metal layer often relies on laser cutting on the silicone substrate, and it is difficult to effectively avoid the damage of the silicone substrate and the problem of the retention of metal residues on the silicone substrate.

[0046] Aiming at the defects and blanks in the prior art, the present invention provides a platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact and a preparation method thereof. The design of the three-dimensional structure of the micro-top hat can effectively improve the signal-to-noise ratio of the cortical microelectrode for recording signals, thereby improving the quality of the recorded signals. At the same time, the application of the stamping process and the laser cutting process to form the silicone substrate after patterning the platinum-iridium alloy sheet ensures the cleanliness and integrity of the silicone substrate, and improves the reliability and safety of the electrode to a certain extent.

[0047] The microelectrode includes a bottom silicone substrate, a platinum-iridium alloy micro-top hat, a platinum-iridium alloy wire, and a top silicone substrate.

[0048] The bottom silicone substrate is obtained by the method of micro-pressing and immersing it into semi-solid silicone or the method of in-situ spin coating.

[0049] The platinum-iridium alloy micro-top hat has circumferentially arrayed small holes at the brim and is connected to the platinum-iridium alloy wire.

[0050] The upper surface of the top silicone substrate in the three-dimensional structure of the micro-top hat is flush with the upper surface of the platinum-iridium alloy micro-top hat to ensure gapless contact with the cortical tissue.

[0051] The bottom silicone substrate and the top silicone substrate are made of elastomeric materials, such as polydimethylsiloxane (PDMS), polyurethane (PU), platinum-catalyzed silicone rubber (such as Ecoflex), etc.

[0052] In addition to platinum-iridium alloy, metals such as platinum and gold can also be used for the micro top cap and the wire.

[0053] The height of the three-dimensional structure of the micro top cap is 100 to 500 micrometers.

[0054] The overall size and the number of electrode points of the cortical microelectrode are determined according to the target cortical structure and size of the attachment object. Among them, the diameter of the microelectrode contact is 50 to 200 micrometers.

[0055] The preparation method steps are as follows:

[0056] The first step: Paste the water-soluble tape on the surface of the platinum-iridium alloy sheet;

[0057] The second step: Stamping to form a platinum-iridium alloy micro top cap;

[0058] The third step: Fix the platinum-iridium alloy sheet adhered to the water-soluble tape on the carrier with tape. After laser cutting the platinum-iridium alloy sheet, peel off the non-retained area of the platinum-iridium alloy sheet, and the remaining retained area is the platinum-iridium alloy wire;

[0059] The fourth step: Slightly press the platinum-iridium alloy wire downward and immerse it in the semi-solid silicone, or spin-coat the liquid silicone, and wait for it to solidify to form the bottom silicone substrate;

[0060] The fifth step: Use hot water to dissolve the water-soluble tape;

[0061] The sixth step: Flip the electrode so that the platinum-iridium alloy wire faces upward, attach a fan-shaped polymer film at the end of the platinum-iridium alloy wire as a temporary shield, spin-coat the liquid silicone, then tear off the fan-shaped polymer film to expose the welding area at the end of the platinum-iridium alloy wire, and wait for the liquid silicone to heat and solidify to form the top silicone substrate;

[0062] The seventh step: Use the laser cutting process to cut through the two layers of silicone substrates to form the outer contour of the electrode, and cut off the top silicone substrate on the upper surface of the three-dimensional structure of the micro top cap until the upper surface of the top silicone substrate in the cut area is flush with the upper surface of the platinum-iridium alloy micro top cap to form the microelectrode contact;

[0063] The eighth step: Peel off the non-retained silicone to release the electrode.

[0064] Further, the second and third process steps can be replaced by first laser cutting the platinum-iridium alloy sheet to form a toothed profile, then stamping to form a platinum-iridium alloy micro top cap, and finally using the laser cutting process to obtain the platinum-iridium alloy wire connected to the platinum-iridium alloy micro top cap. Specific embodiments:

[0066] The schematic diagrams of the overall structures of the micro top cap three-dimensional contact platinum-iridium cortical microelectrodes provided in Embodiment 1 and Embodiment 3 of the present invention are referred to Figure 1As shown, only the micro-top cap stereocontact platinum-iridium cortical microelectrode of the 4×4 array micro-top cap three-dimensional structure 1 is shown. The exploded view of the micro-top cap three-dimensional structure 1 is referred to Figure 2 As shown, the micro-top cap three-dimensional structure 1 is divided into three parts. From bottom to top, they are the bottom silicone substrate 5, the platinum-iridium alloy micro-top cap 6, and the top silicone substrate 7. It can be observed that the microelectrode contact 2 is flush with the upper surface of the top silicone substrate 7, realizing the gapless contact between the microelectrode contact 2 and the cerebral cortex tissue.

[0067] In the first embodiment, referring to Figure 3 As shown, a schematic diagram of the preparation process flow of a micro-top cap stereocontact platinum-iridium cortical microelectrode is mainly divided into the following eight steps:

[0068] The first step is to paste the water-soluble tape flat on the platinum-iridium alloy sheet. The water-soluble tape can effectively protect the back of the platinum-iridium alloy sheet. After the water-soluble tape dissolves, a clean microelectrode contact is exposed. Heat-peelable tape can be used as an alternative. The platinum-iridium alloy sheet is used as the metal layer, and its thickness is 50 microns.

[0069] The second step is to punch from the platinum-iridium alloy sheet to the side of the water-soluble tape using the punch of the stamping die 12. The die is placed at the corresponding position on the side of the water-soluble tape to punch out the platinum-iridium alloy micro-top cap 6. The column array size of the punch needs to be determined according to the design size of the micro-top cap three-dimensional structure 1.

[0070] The third step is to fix the platinum-iridium alloy sheet adhered to the water-soluble tape flat on the glass sheet with polyimide (PI) tape, and laser-cut the platinum-iridium alloy sheet to pattern it, forming the platinum-iridium alloy wire 4 and the laser micropores 8. The width of the platinum-iridium alloy wire 4 is 40 microns, and the diameter of the laser micropores 8 is 20 microns. Use tweezers to peel off the non-retained area of the platinum-iridium alloy sheet, and the remaining retained area is the platinum-iridium alloy wire. At the same time, the laser micropores 8 can enhance the adhesion of the two-layer silicone substrates 3 and improve the stability of the cortical microelectrode.

[0071] The fourth step is to heat the semi-solid silicone, immerse the platinum-iridium alloy wire downward with slight pressure into the semi-solid silicone. After the semi-solid silicone forms a film on the patterned platinum-iridium alloy surface, lower the heating temperature and wait for it to solidify to form the bottom silicone substrate, making the silicone surface present a non-flowing viscous deformable state. Then apply pressure to the patterned alloy sheet adhered to the water-soluble tape and press it until the alloy sheet just sinks into the semi-solid silicone. After the semi-solid silicone solidifies, form the bottom silicone substrate 5 with a thickness of 100 microns.

[0072] The fifth step is to use hot water to dissolve the water-soluble tape until the water-soluble tape is completely removed, and remove the electrode moisture by natural evaporation or heating and drying.

[0073] Step 6: Flip the electrode so that the platinum-iridium alloy wire 4 faces upward, and attach a fan-shaped polymer film to the tail end of the platinum-iridium alloy wire 4 as a temporary shield, spin-coat liquid silicone, and then tear off the fan-shaped polymer film to expose the welding area at the tail end of the platinum-iridium alloy wire 4. After the liquid silicone is heated and cured, a top layer of silicone substrate 7 is formed, which still maintains a micro-top hat three-dimensional structure with a thickness of 100 microns.

[0074] Step 7: Use laser cutting technology to cut through the two layers of silicone substrate 3 to form the outer contour of the cortical microelectrode, and remove the top silicone substrate 7 on the upper surface of the micro-top cap three-dimensional structure 1 until the platinum-iridium alloy micro-top cap 6 is exposed to form the microelectrode contact 2. Ensure that the upper surface of the top silicone substrate 7 is flush with the upper surface of the platinum-iridium alloy micro-top cap 6 after removal, and the diameter of the microelectrode contact is 80 microns;

[0075] In the eighth step, use tweezers to peel off the non-retained part of the silicone, and then peel off the fan-shaped polymer film at the tail end of the platinum-iridium alloy wire 4 to expose the tail end of the platinum-iridium alloy wire 4 and release the electrode.

[0076] In Example 2, referring to Figure 4 As shown, the process steps and the structure of the platinum-iridium alloy micro-top cap 6 are changed. The difference from the structure of the first embodiment is that the platinum-iridium alloy micro-top cap 6 adds a tooth-shaped profile 10 to replace the laser micro-hole 8 at the brim of the platinum-iridium alloy micro-top cap 6. The process steps of the first embodiment are different in that: before step 2, a laser cutting process is added to form a tooth-shaped profile, referring to Figure 4 (a), and then stamping is performed according to the method described in step 3 to form a platinum-iridium alloy micro-top cap 6, referring to Figure 4 As shown in (b), when the laser cutting process in step 4 forms the metal, the platinum-iridium alloy wire 4 is directly connected to the platinum-iridium alloy micro-top cap 6, referring to Figure 4 (c) As shown. The tooth-shaped profile structure is used to form a larger micro-top cap three-dimensional structure height, reduce the difficulty of stamping and improve the yield rate. At the same time, the tooth-shaped profile structure can ensure that when the top silicone base is spin-coated, the silicone contacts the bottom silicone base layer through the tooth-shaped profile gap, which is convenient for better anchoring the platinum-iridium alloy layer sandwiched in the middle and providing better packaging mechanical strength.

[0077] In Example 3, referring to Figure 5As shown, the specific implementation steps are the same as those in the first embodiment. The difference is that in the fourth step, the bottom silicone substrate 5 is formed by in-situ spin coating. The platinum-iridium alloy sheet is placed with one side facing up, and a fan-shaped polymer film is attached to the tail end of the platinum-iridium alloy wire 4. Liquid silicone is spin-coated, and then the fan-shaped polymer film is torn off to expose the welding area at the tail end of the platinum-iridium alloy wire 4. After the silicone is cured, the bottom silicone substrate 5 is formed. During the spin coating process, the recessed area of the platinum-iridium alloy micro-top cap 6 is filled by the self-leveling of the liquid silicone to obtain a flat bottom silicone substrate 5. At the same time, the rotation speed is controllable during the spin coating process, so as to obtain a thinner silicone substrate.

Claims

1. A platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact, characterized in that, It includes a bottom silicone substrate, a platinum-iridium alloy micro-top cap, a platinum-iridium alloy wire, and a top silicone substrate; The bottom silicone substrate, the platinum-iridium alloy micro-top cap, and the top silicone substrate are all in the shape of a round straw hat. From bottom to top, they are the bottom silicone substrate, the platinum-iridium alloy micro-top cap, and the top silicone substrate, and the three are buckled together. Among them, the materials of the platinum-iridium alloy micro-top cap and the platinum-iridium alloy wire are platinum-iridium alloy; A plurality of laser micro-holes are provided in a circle on the brim of the platinum-iridium alloy micro-top cap; the upper surface of the platinum-iridium alloy micro-top cap is a micro-electrode contact; One end of the platinum-iridium alloy wire is connected to the brim of the platinum-iridium alloy micro-top cap, and the other end extends out of the bottom silicone substrate and the top silicone substrate for connection with an external device; The top of the top silicone substrate is hollowed out, and the micro-electrode contact is flush with the upper surface of the top silicone substrate.

2. The platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 1, characterized in that, Both the bottom silicone substrate and the top silicone substrate are made of an elastomer material.

3. The platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 2, characterized in that, The elastomer material is polydimethylsiloxane PDMS or polyurethane PU or platinum-catalyzed silicone rubber.

4. The platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 1, characterized in that, The materials of the platinum-iridium alloy micro-top cap and the platinum-iridium alloy wire are replaced with platinum or gold.

5. The platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 1, characterized in that, The height of the platinum-iridium alloy micro-top cap is 100 - 500 microns.

6. The platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 1, characterized in that, The diameter of the micro-electrode contact is 50 - 200 microns.

7. A method for preparing a platinum-iridium cortical microelectrode with a micro-top hat three-dimensional contact according to claim 1, characterized in that, It includes the following steps: Step 1: Stick a water-soluble tape on the surface of the platinum-iridium alloy sheet; Step 2: Use the punch of the stamping die to punch from the platinum-iridium alloy sheet to the side of the water-soluble tape, and place the die at the corresponding position on the side of the water-soluble tape to form the cap of the platinum-iridium alloy micro-top cap by stamping; Step 3: Fix the platinum-iridium alloy sheet adhered to the water-soluble tape on the carrier with tape, and laser cut the platinum-iridium alloy sheet to form the brim of the platinum-iridium alloy micro-top cap, the platinum-iridium alloy wire, and the laser micro-holes on the brim; peel off the non-retained area of the platinum-iridium alloy sheet, and the remaining retained area is the platinum-iridium alloy wire and the platinum-iridium alloy micro-top cap; Step 4: Heat the semi-solid silicone, press the platinum-iridium alloy wire downward from the side of the water-soluble tape so that the platinum-iridium alloy wire is immersed in the semi-solid silicone. After the semi-solid silicone forms a film on the surface of the platinum-iridium alloy, lower the heating temperature to make the surface of the silicone present a non-flowing viscous deformable state, and then apply pressure to the platinum-iridium alloy micro-top cap from the side of the water-soluble tape until the semi-solid silicone completely fills the internal space of the cap of the platinum-iridium alloy micro-top cap. After the semi-solid silicone cures, form the bottom silicone substrate; Step 5: Dissolve the water-soluble tape with hot water; Step 6: Attach a fan-shaped polymer film to the tail end of the platinum-iridium alloy wire as a temporary shield, spin-coat liquid silicone on the area where the platinum-iridium alloy wire and the platinum-iridium alloy micro-top cap are located, and then tear off the fan-shaped polymer film to expose the welding area at the tail end of the platinum-iridium alloy wire. After the liquid silicone is heated and cured, form the top silicone substrate; Step 7: Use the laser cutting process to cut through the two layers of silicone substrates to form the outer contour of the micro-electrode, and cut off the top area of the top silicone substrate to form a hollow, so that the upper surface of the top silicone substrate is flush with the micro-electrode contact of the platinum-iridium alloy micro-top cap; Step 8: Peel off the non-retained silicone outside the outer contour of the micro-electrode to release the electrode.

8. The method for preparing a microelectrode according to claim 7, characterized in that, Step 2 and Step 3 are replaced with the following steps: A platinum-iridium alloy sheet is laser-cut to form a toothed contour, then stamped to form a platinum-iridium alloy micro-top cap, and finally a platinum-iridium alloy wire connected to the platinum-iridium alloy micro-top cap is obtained using a laser cutting process.

9. The method for preparing a microelectrode according to claim 7, characterized in that, The step 4 is replaced with: An in-situ spin-coating method is used to form the bottom silicone substrate: Place the platinum-iridium alloy sheet with one side facing up, attach a fan-shaped polymer film to the end of the platinum-iridium alloy wire, spin-coat liquid silicone, and then tear off the fan-shaped polymer film to expose the welding area at the end of the platinum-iridium alloy wire. After the silicone cures, the bottom silicone substrate is formed; during the spin-coating process, the concave area of the platinum-iridium alloy micro-top cap is filled by the self-leveling of the liquid silicone to obtain a flat bottom silicone substrate.

10. The method for preparing a microelectrode according to claim 7, characterized in that, The thickness of the platinum-iridium alloy sheet is 15 - 100 microns, the width of the platinum-iridium alloy wire is 30 - 500 microns, the diameter of the laser micro-hole is 20 - 200 microns, and the thicknesses of both the bottom silicone substrate and the top silicone substrate are 20 - 500 microns.

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