Neural microelectrode with superfine silicon fiber probe and preparation and treatment method of neural microelectrode

Abstract

The invention discloses a neural microelectrode with a superfine silicon fiber probe and a preparation and treatment method of the neural microelectrode. The neural microelectrode comprises an electrode base and one or more silicon fiber electrode bundles. And the silicon fiber electrode beam comprises a plurality of silicon fiber probes which are mutually independent. And one or more microelectrode points are arranged on the silicon fiber probe. The length and the width of the section of the silicon fiber probe are both smaller than or equal to 15 micrometers. And the distance between two adjacent silicon fiber probes is less than or equal to 15 microns. A plurality of dispersed silicon fiber probes in a silicon fiber electrode bundle are gathered into a bundle of fiber structures which are tightly arranged by using polyethylene glycol, and a hardened layer is formed, so that the implantation rigidity of the neural microelectrode is greatly improved, the polyethylene glycol is naturally degraded after implantation is completed in vivo, and the nerve microelectrode has a good application prospect. And the plurality of silicon fiber probes in the gathered silicon fiber electrode beam are recovered into a dispersed soft structure, so that the flexibility is recovered and the tissue inflammatory response is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of implantable silicon-based neural microelectrodes for brain-computer interfaces; specifically, it relates to a method for micro-fabrication preparation and implantation of neural microelectrodes for neural recording, which has low invasiveness and long-term biocompatibility. Background Art

[0002] At present, implantable neural microelectrodes can be divided into two categories: rigid electrodes and flexible electrodes. Among them, rigid electrodes include microwire electrodes, Utah electrodes and Michigan electrodes. Among them, microwire electrodes have the advantages of simple structure and reliable performance. However, there are still difficulties in its mass production. The Utah electrode array is the only implantable microelectrode array approved by the US FDA for clinical use, and the recording time can be up to several years. Its probe length is about 1mm, which is suitable for neural recording in the cerebral cortex or shallow brain areas. The Michigan electrode uses planar photolithography technology to achieve extremely high spatial resolution, which can achieve recording and stimulation in deeper brain areas. NeuroNexus and Blackrock Microsystems in the United States, Cambridge NeuroTech in the United Kingdom, IMEC in Belgium, etc. can all provide commercial experimental electrodes. However, the Michigan electrode has a high Young's modulus and poor biocompatibility, which cannot adapt to cortical recording and has insufficient long-term recording stability. In recent years, with the rapid development of flexible electronic technology, flexible neural microelectrode arrays based on polymer substrates have become a new research hotspot. Flexible electrodes include probe electrodes for deep brain spikes / LFP recording and planar electrodes for cortical surface ECoG signal acquisition. Compared with silicon-based Michigan electrodes, polymer electrodes have a lower Young's modulus and can significantly reduce the risk of inflammatory response. However, the commonly used flexible neural microelectrodes still have problems such as implantation difficulties and body fluid corrosion.

[0003] After searching the existing technical literature, it is found that the preparation and implantation technology of "rigid-flexible" neural microelectrode arrays by combining flexible electrodes with rigid degradable hardening materials is crucial to achieve high spatiotemporal resolution and high biocompatibility neural recording. In 2017, C. Xie's team at the University of Texas at Austin used surface tension to attach flexible neural microelectrodes to glass optical fibers and capillary glass tubes to achieve assisted implantation in the prefrontal cortex of mice [Zhao Z., Lan L., Wei X., et al. Nanoelectronic Coating Enabled Versatile Multifunctional Neural Probes. Nano Letters, 2017, 17(8):4588.]. In 2020, the brain-machine interface sensor Link V 0.9 released by Neuralink in the United States also uses microneedles to grasp flexible electrodes for visual assisted implantation [MUSK E. An integrated brain-machine interface platform with thousands of channels. Journal of medical Internet research, 2019, 21(10): e16194.]. However, the process of microneedle-assisted implantation is still relatively complicated and requires high precision equipment. The principle of biodegradable material-assisted implantation is to use the "rigid-flexible combination" of flexible electrodes and biodegradable hardened materials to achieve rapid implantation. After the implantation is completed, the biodegradable material dissolves in the body to restore the flexibility of the electrode. In 2014, Professor C. Lee's team at the National University of Singapore inserted a flexible polyimide probe into molten maltose. By slowly pulling, different thicknesses of solidified maltose can be coated on the probe surface to give it a certain rigidity [Xiang Z., Yen SC, Xue N., et al. Ultra-thin flexible polyimide neural probe embedded in a dissolvable maltose-coated microneedle. Journal of Micromechanics & Microengineering, 2014, 24(6):065015.].In 2019, Fang Ying's research group at the National Center for Nanotechnology and Nanotechnology achieved rigid-flexible transformation by immersing the neural tassels in molten PEG and then slowly pulling them up to solidify [Zou L., Tian H., Guan S., et al. Self-assembled multifunctional neuralprobes for precise integration of optogenetics and electrophysiology. Nature Communications, 2021(12):5871.]. However, the implantation of degradable materials will increase the thickness of the probes and thus increase implantation damage. Moreover, this method is prone to probe entanglement and inaccurate positioning when implanting multi-probe flexible microelectrode arrays. Summary of the invention

[0004] The purpose of the present invention is to provide a neural microelectrode with an ultra-fine silicon fiber probe and a preparation method thereof in view of the defects in the prior art.

[0005] In a first aspect, the present invention provides a neural microelectrode having an ultrafine silicon fiber probe, which includes an electrode base and one or more silicon fiber electrode bundles. The silicon fiber electrode bundle includes a plurality of silicon fiber probes that are independent of each other. The silicon fiber probe is provided with one or more microelectrode points. The cross-sectional length and width of the silicon fiber probe are both less than or equal to 15 μm. The spacing between two adjacent silicon fiber probes is less than or equal to 15 μm.

[0006] The above-mentioned neural microelectrode uses a flexible ultrafine silicon fiber probe as a recording electrode substrate, and combines a degradable polyethylene glycol solution to pre-treat the silicon fiber probe, so as to achieve precise minimally invasive implantation of the flexible ultrafine silicon fiber probe in the brain; through the combination of flexible silicon fiber and polyethylene glycol, on the one hand, the silicon fiber probe can make the recording electrode have a very small implant footprint, thereby reducing brain tissue damage caused by the implantation process, and on the other hand, polyethylene glycol can ensure that the bundled flexible ultrafine silicon fiber probe has sufficient rigidity during the implantation process, thereby improving the implantation accuracy of the electrode in the body. In addition, after polyethylene glycol degrades in the body, it can make the silicon fiber electrode have good flexibility, thereby reducing brain tissue damage caused by mechanical mismatch.

[0007] Preferably, one or more probe handles extend from the electrode base, and a silicon fiber electrode bundle extends from the tip of each probe handle.

[0008] Preferably, the neural microelectrode is provided with a conductive layer wrapped between an upper insulating layer and a lower insulating layer. The conductive layer includes a plurality of electrode pads located at the electrode base, and signal lines extending from the electrode pads to the corresponding silicon fiber probe tips. The microelectrode point is formed by a window through which the signal line is exposed at the silicon fiber probe tip.

[0009] Preferably, on the silicon fiber probe, the insulating layer wrapping the signal line is made of silicon oxide / silicon nitride. The length of the silicon fiber probe is 1 mm to 10 mm.

[0010] Preferably, the thickness of the conductive layer is 100 nm to 500 nm, and the sum of the thickness of the upper insulating layer and the lower insulating layer is 100 nm to 1000 nm.

[0011] Preferably, the silicon fiber probes on the silicon fiber electrode bundle are gathered into a bundle structure that fits together and is wrapped with a degradable hardening layer. The degradable hardening layer is made of a substance that can be automatically degraded in the human body.

[0012] Preferably, the material of the degradable hardened layer is polyethylene glycol.

[0013] Preferably, the silicon fiber probes in the same silicon fiber electrode bundle are arranged in a straight line along the width direction of the neural microelectrode, and the lengths decrease successively along the arrangement direction.

[0014] In a second aspect, the present invention provides a method for preparing a neural microelectrode having an ultrafine silicon fiber probe, characterized in that it comprises the following steps: Step 1. Use an SOI silicon wafer as a substrate; the SOI silicon wafer includes a top silicon layer with a thickness of 10 microns, a buried oxide layer with a thickness of 2 microns, and a bottom silicon layer with a thickness of 400 microns.

[0015] Step 2. Deposit a lower insulating layer composed of silicon oxide / silicon nitride on the front side of the SOI silicon wafer.

[0016] Step 3. depositing metal Cr / Au on the lower insulating layer to form a metal layer; Step 4. Pattern the metal layer into micro-electrode points, signal lines and electrode pads to form a conductive layer.

[0017] Step 5. Depositing an upper insulating layer composed of silicon oxide / silicon nitride on the conductive layer.

[0018] Step 6. Pattern the upper insulating layer to expose the microelectrode points and electrode pads.

[0019] Step 7. Use photolithography and reactive ion etching to expose the front contour removal area; the front contour removal area is the area outside the silicon fiber probe; then use a deep silicon etching system to remove the top layer of silicon in the front contour removal area on the SOI silicon wafer to form the front contour of the neural microelectrode.

[0020] Step 8. Perform spin lithography on the back of the SOI silicon wafer to pattern the back thinning area. The back thinning area is the area on the back of the neural microelectrode corresponding to the silicon fiber probe.

[0021] Step 9. Spin-coat a layer of photoresist to protect the front pattern structure on the front side of the SOI silicon wafer and bake the photoresist.

[0022] Step 10. Use a thermal release blue film to fix the SOI silicon wafer face down onto another wafer, and then thin the back profile thinning area of ​​the SOI silicon wafer by deep silicon etching to a depth of 400 microns until the buried oxide layer is exposed.

[0023] Step 11. Use reactive ion etching to remove the 2-micron-thick buried oxide layer on the back of the SOI silicon wafer; then heat the thermal release blue film to release the SOI silicon wafer from another wafer.

[0024] Step 12. Debond the SOI silicon wafer to obtain neural microelectrodes.

[0025] In a third aspect, the present invention provides a neural microelectrode processing method, which uses the aforementioned neural microelectrode with an ultrafine silicon fiber probe; the neural microelectrode processing method is as follows: The silicon fiber electrode bundle of the neural microelectrode is immersed in a saturated polyethylene glycol solution for a preset period of time and then taken out to dry. All silicon fiber probes in the silicon fiber electrode bundle are gathered into a bundle under the action of the liquid surface energy, and the precipitated polyethylene glycol forms a degradable hardened layer, which improves the overall rigidity of the silicon fiber electrode bundle.

[0026] In a fourth aspect, the present invention provides another neural microelectrode processing method, which uses the aforementioned neural microelectrode with an ultrafine silicon fiber probe; the neural microelectrode processing method is as follows: The silicon fiber electrode bundle of the neural microelectrode is immersed in molten polyethylene glycol liquid for a preset period of time and then taken out and cooled. All silicon fiber probes in the silicon fiber electrode bundle are gathered into a bundle under the action of the liquid surface energy, and the polyethylene glycol solidifies to form a degradable hardened layer, thereby improving the overall rigidity of the silicon fiber electrode bundle.

[0027] The present invention has the following beneficial effects: 1. The present invention carries multiple recording electrodes on a bundle-like silicon fiber electrode bundle, greatly reducing the cross-sectional size of the silicon probe to 15*15μm 2Within this range, the silicon fiber probe not only has good flexibility to reduce mechanical mismatch, but also can significantly reduce the brain tissue damage caused by implantation footprint.

[0028] 2. The present invention utilizes polyethylene glycol to aggregate the dispersed multiple silicon fiber probes in the silicon fiber electrode bundle into a tightly arranged bundle of fiber structures and form a hardened layer, thereby greatly increasing the implantation rigidity of the neural microelectrode. After implantation in the body, the polyethylene glycol will naturally degrade, and the multiple silicon fiber probes in the aggregated silicon fiber electrode bundle will return to a dispersed soft structure, thereby restoring flexibility and reducing tissue inflammatory response.

[0029] 3. The silicon fiber electrode structure used in the present invention has a certain degree of overall flexibility but is still partially rigid, which allows the silicon fiber electrode to swing slightly with the brain tissue after implantation, thereby reducing the glial reaction caused by the cutting movement. In addition, the local rigidity allows the probe to quickly return to its original position after implantation, so that the electrode point can be accurately positioned in the target brain area without dislocation and entanglement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the silicon fiber electrode of the present invention; Figure 2 It is a schematic diagram of the structure of the silicon fiber electrode bundle in the present invention; Figure 3 This is a process flow chart of micro-machining preparation of neural microelectrodes in Example 1 of the present invention; Figure 4 Schematic diagram of the pretreatment and implantation process of the neural microelectrode in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings.

[0032] Example 1 like Figure 1 and 2 As shown, a neural microelectrode with an ultrafine silicon fiber probe uses single crystal silicon as the main substrate material, including an electrode base 3, and one or more probe handles 2 extending from the side edge of the electrode base 3. A silicon fiber electrode bundle 1 extends from the tip of each probe handle; the silicon fiber electrode bundle 1 includes a plurality of silicon fiber probes 1-1 that are independent of each other. One or more microelectrode points 1-2 are provided on the silicon fiber probe 1-1. Each silicon fiber probe 1-1 is arranged in a straight line along the width direction of the neural microelectrode.

[0033] The neural microelectrode is provided with a conductive layer. The conductive layer is wrapped between the upper insulating layer and the lower insulating layer. The conductive layer includes a plurality of electrode pads 3-1 located at the base of the electrode, and a signal line extending from the electrode pads 3-1 to the tip of the corresponding silicon fiber probe 1-1. A window exposing the signal line is provided at the tip of the silicon fiber probe 1-1 to form a microelectrode point 1-2. Each electrode pad 3-1 can be connected to only one microelectrode point 1-2, or can be simultaneously connected to microelectrode points 1-2 on multiple silicon fiber probes 1-1 extending from the same probe handle.

[0034] The silicon fiber probe 1-1 is a slender structure with an insulating layer wrapping the signal line. The cross-sectional length and width of the silicon fiber probe 1-1 are both less than or equal to 15μm; the length is 1mm-10mm. The spacing between two adjacent silicon fiber probes 1-1 is less than or equal to 15μm;

[0035] The thickness of the conductive layer is 100nm-500nm, and the material is Cr / Au; the sum of the thickness of the upper insulating layer and the lower insulating layer is 100nm-1000nm, and the materials are silicon oxide and silicon nitride, and the ratio of the thickness of silicon oxide to silicon nitride is 4:1.

[0036] The silicon fiber electrode bundle 1 has local rigidity and can be precisely positioned. Specifically, the overall length of the silicon fiber probe 1-1 is relatively long and can be bent as a whole; but the length of the area where the microelectrode point 1-2 is located is very short and can hardly be bent; therefore, the microelectrode point 1-2 of the silicon fiber probe 1-1 has local rigidity, and the microelectrode point 1-2 cannot be bent at a large angle, thereby avoiding inaccurate positioning of the electrode point. At the same time, the multiple silicon fiber probes 1-1 of the silicon fiber electrode bundle 1 in this embodiment can be aggregated into a silicon fiber bundle under the action of the surface energy of the degradable material, thereby increasing the implant rigidity, and the aggregated silicon fiber bundle can be dispersed into multiple bundles after the degradable material is dissolved, thereby restoring flexibility.

[0037] In some embodiments, the lengths of the silicon fiber probes 1 - 1 in the same silicon fiber electrode bundle 1 decrease sequentially along the arrangement direction, so that the silicon fiber electrode bundles 1 have sharper tips after being gathered into a bundle.

[0038] like Figure 3 As shown, the neural microelectrode with ultrafine silicon fiber probe is prepared on a single crystal silicon substrate by micromachining technology, and the steps are as follows: Step 1. See Figure 3 In part (1), a 4-inch SOI silicon wafer was used as the substrate (top layer was 5 μm thick, buried oxide layer was 1 μm thick, bottom layer was 300 μm thick), ultrasonically cleaned in acetone, alcohol, and deionized water for 5 min, dried with nitrogen, and then baked on a hot plate at 180 °C for 15 min before use.

[0039] Step 2. See Figure 3In part (2), a lower insulating layer composed of silicon oxide / silicon nitride is deposited on the front side of the substrate using a plasma enhanced chemical vapor deposition system (PECVD); wherein the thickness of the silicon oxide / silicon nitride is 400 nm / 100 nm, respectively.

[0040] Step 3. See Figure 3 In part (3), a magnetron sputtering system is used to deposit metal Cr / Au on the lower insulating layer to form a metal layer; wherein the thickness of Cr / Au is 30nm / 300nm respectively.

[0041] Step 4. Use photolithography and reactive ion etching to pattern the metal layer into micro-electrode points 1-2, signal lines and electrode pads 3-1 to form a conductive layer.

[0042] Step 5. See Figure 3 In part (4), an upper insulating layer composed of silicon oxide / silicon nitride is deposited on the metal layer using PECVD; wherein the thickness of the silicon oxide / silicon nitride is 400nm / 100nm, respectively.

[0043] Step 6. See Figure 3 In parts (5) and (6), the upper insulating layer is patterned using photolithography and reactive ion etching to form exposed electrode points and electrode pad windows.

[0044] Step 7. See Figure 3 In part (7), photolithography and reactive ion etching are used to expose the outline of the front deep silicon etching, and then a deep silicon etching system is used to remove the 10 μm thick top layer of silicon on the outline to form the front outline of the neural microelectrode.

[0045] Step 8. See Figure 3 In part (8), spin lithography is performed on the back side of the substrate to pattern the area on the back side that needs to be thinned.

[0046] Step 9. Re-spin coat a 5 μm thick photoresist layer on the front side of the substrate to protect the front graphic structure. After completion, place the substrate silicon wafer into an oven to bake the photoresist.

[0047] Step 10. Use a thermal release blue film to fix the substrate face down onto another 6-inch wafer, and then place it into a deep silicon etching system for backside thinning.

[0048] Step 11. Use reactive ion etching to remove the 1 μm thick buried oxide layer on the back of the substrate, then heat the thermal release blue film to above 140° C. and remove the substrate.

[0049] Step 12. Place the substrate in hot acetone, alcohol and deionized water for degumming, and after drying, use a degumming machine to degumming again for 20 minutes.

[0050] like Figure 4 As shown, the neural microelectrode with ultrafine silicon fiber probe needs to be pre-processed before being implanted into the human body. The specific process of pre-processing is as follows: Step 1. Prepare a saturated polyethylene glycol aqueous solution: Use a beaker to measure 100 mL of deionized water, and then add excess polyethylene glycol (molecular weight 4000) until the solution is saturated.

[0051] Step 2. Slowly immerse the silicon fiber electrode bundle 1 of the neural microelectrode into the saturated polyethylene glycol solution for 5s to 10s, then slowly pull it out of the liquid surface and dry it naturally at room temperature in the air.

[0052] Step 3. During the evaporation of water in the polyethylene glycol solution, all the silicon fiber probes 1-1 in the silicon fiber electrode bundle 1 are aggregated into a tightly arranged bundle under the action of the liquid surface energy, and the precipitated polyethylene glycol forms a degradable hardened layer, thereby greatly increasing the implantation rigidity of the silicon fiber electrode bundle 1.

[0053] After pretreatment, a silicon fiber electrode bundle 1 coated with a polyethylene glycol degradable hardening layer can be obtained; the user slowly implants the silicon fiber electrode bundle 1 with increased hardness into the cerebral cortex; the polyethylene glycol degradable hardening layer begins to degrade after entering the body, and the degradation time is 5 minutes to 10 minutes. The silicon fiber bundle disperses and restores flexibility, thereby completing precise minimally invasive implantation.

[0054] In some embodiments, the degradable hardened coating 4 can also be directly coated and sealed after the neural microelectrode is prepared. When implantation is required, the neural microelectrode can be directly taken out and used, so as to simplify the implantation operation steps. The thickness of the degradable hardened coating is 0.5 μm to 5 μm.

[0055] Example 2 A neural microelectrode with an ultrafine silicon fiber probe. The difference between this embodiment and embodiment 1 is that the pretreatment process of the neural microelectrode before implantation into the human body is different; the specific pretreatment process in this embodiment is as follows: Step 1. Weigh 100 g of polyethylene glycol particles (molecular weight 4000) in a beaker, and then heat the polyethylene glycol particles to 80°C on a hot plate until they melt into a liquid state.

[0056] Step 2. Slowly immerse the fiber bundle of the silicon fiber electrode into molten polyethylene glycol for 5s to 10s, and then slowly pull it out of the liquid surface; the polyethylene glycol on the silicon fiber electrode bundle 1 that is out of the liquid surface naturally solidifies at room temperature in the air to form a degradable hardened layer.

[0057] After pretreatment, a silicon fiber electrode bundle 1 coated with a polyethylene glycol degradable hardening layer can be obtained; the user slowly implants the silicon fiber electrode bundle 1 with increased hardness into the cerebral cortex; the polyethylene glycol degradable hardening layer begins to degrade after entering the body, and the degradation time is 15 minutes to 30 minutes, and the silicon fiber bundle disperses and restores flexibility, thereby completing precise minimally invasive implantation.

[0058] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A neural microelectrode having an ultrafine silicon fiber probe, comprising an electrode base (3); characterized in that: It also comprises one or more silicon fiber electrode bundles (1); the silicon fiber electrode bundle (1) comprises a plurality of silicon fiber probes (1-1) that are independent of each other; one or more microelectrode points (1-2) are provided on the silicon fiber probes (1-1); the cross-sectional length and width of the silicon fiber probes (1-1) are both less than or equal to 15 μm; and the spacing between two adjacent silicon fiber probes (1-1) is less than or equal to 15 μm.

2. The neural microelectrode with ultrafine silicon fiber probe according to claim 1, characterized in that: One or more probe handles (2) extend from the electrode base (3); a silicon fiber electrode bundle (1) extends from the tip of each probe handle.

3. The neural microelectrode with ultrafine silicon fiber probe according to claim 1, characterized in that: The neural microelectrode is provided with a conductive layer wrapped between an upper insulating layer and a lower insulating layer; the conductive layer comprises a plurality of electrode pads (3-1) located at the base of the electrode, and signal lines extending from the electrode pads (3-1) to the tip of a corresponding silicon fiber probe (1-1); the microelectrode point (1-2) is formed by a window at the tip of the silicon fiber probe (1-1) exposing the signal line.

4. The neural microelectrode with ultrafine silicon fiber probe according to claim 3, characterized in that: On the silicon fiber probe (1-1), the insulating layer wrapping the signal line is made of silicon oxide / silicon nitride; the thickness of the conductive layer is 100nm to 500nm; and the sum of the thickness of the upper insulating layer and the lower insulating layer is 100nm to 1000nm.

5. The neural microelectrode with ultrafine silicon fiber probe according to claim 1, characterized in that: The silicon fiber probes (1-1) on the silicon fiber electrode bundle (1) are gathered into a bundle structure that fits together and is wrapped with a degradable hardened layer; the degradable hardened layer is made of a substance that can be automatically degraded in the human body.

6. A neural microelectrode with an ultrafine silicon fiber probe according to claim 5, characterized in that: The material of the degradable hardened layer is polyethylene glycol.

7. The neural microelectrode with ultrafine silicon fiber probe according to claim 1, characterized in that: The silicon fiber probes (1-1) in the same silicon fiber electrode bundle (1) are arranged in a straight line along the width direction of the neural microelectrode, and the lengths decrease successively along the arrangement direction.

8. The method for preparing a neural microelectrode with an ultrafine silicon fiber probe according to claim 1, characterized in that: The following steps are involved: Step 1. Using an SOI silicon wafer as a substrate; the SOI silicon wafer includes a bottom silicon layer, a buried oxide layer, and a top silicon layer stacked in sequence; Step 2. Depositing a lower insulating layer composed of silicon oxide / silicon nitride on the front side of the SOI silicon wafer; Step 3. depositing metal Cr / Au on the lower insulating layer to form a metal layer; Step 4. Patterning the metal layer into micro-electrode points (1-2), signal lines and electrode pads (3-1) to form a conductive layer; Step 5. depositing an upper insulating layer composed of silicon oxide / silicon nitride on the conductive layer; Step 6. Patterning the upper insulating layer to expose the microelectrode points (1-2) and electrode pads; Step 7. Use photolithography and reactive ion etching to expose the front contour removal area, and deep silicon etching to remove the top silicon of the front contour removal area on the SOI silicon wafer to form the front contour of the neural microelectrode; Step 8. Perform spin lithography on the back side of the SOI silicon wafer to pattern the back side contour thinning area; the back side contour thinning area is the area on the back side of the neural microelectrode corresponding to the silicon fiber probe (1-1); Step 9. Spin-coat a layer of photoresist to protect the front pattern structure on the front side of the SOI silicon wafer, and bake the photoresist; Step 10. Use a thermal release blue film to fix the SOI silicon wafer face down on another wafer, and then thin the back profile thinning area of ​​the SOI silicon wafer by deep silicon etching to expose the buried oxide layer; Step 11: Use reactive ion etching to remove the buried oxide layer on the back of the SOI silicon wafer; Then, the thermal release blue film is heated to release the SOI silicon wafer from another wafer; Step 12. Debond the SOI silicon wafer to obtain neural microelectrodes.

9. A neural microelectrode processing method, characterized in that: Using a neural microelectrode with an ultrafine silicon fiber probe as claimed in claim 1; the neural microelectrode processing method is as follows: The silicon fiber electrode bundle (1) of the neural microelectrode is immersed in a saturated polyethylene glycol solution for a preset period of time and then taken out to dry. All silicon fiber probes (1-1) in the silicon fiber electrode bundle (1) are aggregated into a bundle under the action of the liquid surface energy, and the precipitated polyethylene glycol forms a degradable hardened layer, thereby improving the overall rigidity of the silicon fiber electrode bundle (1).

10. A neural microelectrode processing method, characterized in that: Using a neural microelectrode with an ultrafine silicon fiber probe as claimed in claim 1; the neural microelectrode processing method comprises the following steps: The silicon fiber electrode bundle (1) of the neural microelectrode is immersed in a molten polyethylene glycol liquid for a preset period of time and then taken out and cooled. All silicon fiber probes (1-1) in the silicon fiber electrode bundle (1) are gathered into a bundle under the action of the liquid surface energy, and the polyethylene glycol is solidified to form a degradable hardened layer, thereby improving the overall rigidity of the silicon fiber electrode bundle (1).

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