Multi-channel optical fiber neural electrode and preparation method thereof

Abstract

The invention provides a multichannel optical fiber neural electrode and a preparation method thereof. The multi-channel optical fiber neural electrode comprises an optical fiber base body and a flexible microelectrode array integrated on the surface of the optical fiber base body, the optical fiber base body comprises a fiber core and a wrapping layer wrapping the fiber core, and the refractive index of the fiber core is larger than that of the wrapping layer. The flexible microelectrode array comprises a flexible substrate layer, a conductive layer and an insulating layer which are sequentially arranged from the position close to the cladding. The multi-channel optical fiber neural electrode is suitable for a neural electrode, and organically combines the functions of optical transmission and electric signal sensing. The invention further provides a preparation method of the multi-channel optical fiber neural electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of neural optical fibers, and in particular relates to a multi-channel optical fiber neural electrode and a preparation method thereof. Background Art

[0002] As a common light-guiding device, optical fiber is widely used in biology and biomedicine. It uses the principle of total internal reflection of light inside the fiber to transmit optical signals. In neuroscience research, although new optical devices continue to emerge and provide alternatives, optical fiber-based devices still dominate optogenetics research. This is because optical fiber has the advantages of miniaturized design, diverse light source selection, and lossless light transmission, which makes it very suitable for neurological research. In addition, by optimizing the surface area design of optical fiber, it is also possible to expand its sensing and driving functions.

[0003] Although rigid implants are widely used in implant environments due to their reliability, flexible materials are becoming a more ideal choice in neuroscience due to their higher stability and good biocompatibility. Rigid implants may work for a limited time before cracks form under small movements, and often cause gaps between neurons and sensors. More importantly, the movement between rigid implants and brain tissue can trigger an inflammatory response, which can lead to device failure. In contrast, flexible implants can better adapt to the curved morphology of brain tissue, achieve a better match, reduce inflammatory reactions and rejection reactions, and thus improve implant effectiveness.

[0004] However, the curved geometry of optical fibers makes it extremely difficult to integrate other electronic components into them. In recent years, optical fibers made of flexible materials such as optical plastics, synthetic rubbers, and hydrogels have been able to provide mechanical properties that better match soft tissues, helping to reduce tissue damage and achieve closer tissue contact. More importantly, flexible optical fibers have the potential to be an ideal carrier for flexible electronics, enabling the development of optoelectronic fiber devices that are more advanced and complex than traditional optical stimulation. Some cutting-edge research has explored the combination of microwire flexible optical fibers with sensing electrodes (such as electrodes coated with silver nanowires), which provides new ideas for multi-point recording and sensing. However, although multi-point recording can be achieved by adding microwire electrodes, truly flexible optical electrodes have not yet been realized, and coating the surface of optical fibers with silver nanowires cannot effectively achieve multi-point recording. Therefore, the current need is to develop a new fiber optic device suitable for neural electrodes that can organically combine light transmission with electrical signal sensing functions to promote the further development of neural electrode technology. Summary of the invention

[0005] The present invention aims to solve at least one of the above technical problems existing in the prior art. To this end, the present invention provides a multi-channel optical fiber neural electrode, which is suitable for neural electrodes and organically combines optical transmission and electrical signal sensing functions.

[0006] The invention also provides a method for preparing a multi-channel optical fiber neural electrode.

[0007] The first aspect of the present invention provides a multi-channel optical fiber neural electrode, comprising an optical fiber substrate and a flexible microelectrode array integrated on the surface of the optical fiber substrate, wherein the optical fiber substrate comprises a core and a cladding covering the core, the refractive index of the core is greater than the refractive index of the cladding, and the flexible microelectrode array comprises a flexible base layer, a conductive layer and an insulating layer arranged in sequence starting from close to the cladding.

[0008] One of the technical solutions of the present invention regarding the multi-channel optical fiber neural electrode has at least the following beneficial effects:

[0009] Existing flexible multimodal probes are mainly made by making holes for microwires (tungsten wires or copper wires) in flexible optical fibers and integrating them with flexible optical fibers. This method makes it difficult to fuse microwires with flexible optical fibers, and the number of microwires is limited. At the same time, it is necessary to avoid mutual contact between microwires during the fusion process, and the process is difficult to control. There are also methods that use AgNWs deposited on the surface of flexible optical fibers as electrodes, and the flexible optical fibers are immersed in AgNWs solutions to coat the surface with a layer of conductive material. The number of channels of the flexible electrodes prepared by this method is limited, and multi-site recording cannot be achieved. The multi-channel optical fiber neural electrode of the present invention includes an optical fiber substrate and a flexible microelectrode array integrated on the surface of the optical fiber substrate. The softness and flexibility of the optical fiber substrate can facilitate the implantation process and allow the fiber to bend to adapt to the distance and depth of different implantation areas. The flexible microelectrode array on the surface of the optical fiber substrate can achieve multi-site recording on the periphery of the central nervous system.

[0010] The multi-channel optical fiber neural electrode of the present invention has a core with a refractive index greater than that of the cladding, that is, the optical fiber structure is divided into two parts, an inner core with a higher refractive index and an outer cladding with a lower refractive index. When light that meets a certain angle enters the core, total reflection occurs at the interface between the core and the cladding.

[0011] The multi-channel fiber-optic neural electrode technology solution of the present invention combines the advantages of fiber-optic light guidance and the electrical signal collection capabilities of flexible microelectrode arrays, providing a new and multifunctional neural electrode solution. Specifically:

[0012] 1. Multi-channel signal acquisition capability. The core innovation of the technical solution of the present invention is that by integrating a flexible microelectrode array on the surface of the optical fiber substrate, multiple electrodes can be simultaneously contacted with different nerve areas to perform multi-point electrical signal recording. Unlike the existing technology, this design overcomes the limitations of previous microwire integration or silver nanowire coating electrodes, and can effectively expand the number of recording channels and improve the spatial resolution of the signal. This has great application potential for complex neural network research, pathological research, and neural interface technology.

[0013] 2. Flexibility and adaptability of the optical fiber matrix. The flexibility and lightness of the optical fiber matrix of the present invention significantly improve its adaptability during the neural electrode implantation process. The flexible design enables the optical fiber to bend easily and adapt to the complex morphology and position of neural tissue, while reducing the biological damage caused by the relative movement between the hardware and brain tissue during the implantation process. Compared with traditional rigid optical fibers or electrodes, flexible optical fibers can reduce mechanical pressure and damage to brain tissue, thereby reducing the risk of inducing inflammatory and rejection reactions.

[0014] 3. The total internal reflection mechanism ensures the efficiency of optical signal transmission. The difference in refractive index between the core part (core) and the cladding of the optical fiber of the present invention ensures that the optical signal is efficiently transmitted inside the optical fiber through the principle of total internal reflection. When the optical signal passes through the optical fiber, the light that meets a certain angle will be totally reflected at the interface between the core and the cladding, avoiding leakage of the optical signal. This feature ensures the transmission efficiency of optical signals in neural electrode applications and provides stable and precise optogenetic stimulation capabilities.

[0015] 4. Manufacturing process of flexible microelectrode array. Different from the common method of integrating electrodes by metal wire or solution deposition in the prior art, the present invention adopts an integrated design to directly construct a flexible microelectrode array on the surface of the optical fiber substrate. The array is composed of a flexible base layer, a conductive layer and an insulating layer in sequence, which can ensure good electrical signal transmission and avoid electrical interference between different electrodes. The flexible base layer provides good mechanical adaptability for the electrode, enabling it to better contact with neural tissue and maintain stable signal acquisition performance with brain tissue or peripheral nerve structures.

[0016] 5. Improve biocompatibility and stability. Another significant advantage of the multi-channel fiber optic neural electrode solution of the present invention is its excellent biocompatibility. The use of flexible materials can not only better adapt to the curves and surface characteristics of neural tissue, but also reduce mechanical damage during implantation. In addition, this design also reduces the biological rejection reaction caused by mechanical friction between hard implants and brain tissue. Compared with rigid electrodes, flexible electrodes have better long-term implant stability and can continuously provide high-quality electrical signal recordings.

[0017] 6. The versatility of photoelectric coupling. In addition to electrical signal collection, the fiber optic neural electrode of the present invention also has the ability to transmit optical signals, and can provide optogenetic stimulation while performing electrophysiological recording. This photoelectric coupling function provides a wider range of experimental means for neuroscience research. Researchers can achieve optogenetic control and electrophysiological monitoring at the same time and on the same device, providing more accurate regulation and analysis of neural electrical activity.

[0018] 7. Improve the accuracy of experimental control. Since optical fiber can achieve precise light transmission and combine with multi-channel electrical signal acquisition capabilities, this neural electrode can better cooperate with modern neural regulation technology (such as optogenetics) to carry out high-precision experimental design and control. By performing fine light stimulation in specific areas and monitoring multi-point electrical activity in real time, the accuracy and repeatability of neural activity research can be greatly improved.

[0019] 8. Wide application scope. The multi-channel fiber optic neural electrode of the present invention can be widely used in various neuroscience research fields, especially in optogenetics research, neural interface, brain-computer interface (BCI), electroencephalogram (EEG) and peripheral nerve monitoring. It can provide more advanced and efficient experimental tools for these fields and provide new breakthroughs for scientific research and clinical treatment.

[0020] Therefore, the multi-channel fiber-optic neural electrode of the present invention breaks through the design bottleneck of traditional neural electrodes by combining fiber-optic light-guiding technology and flexible microelectrode arrays, providing a more flexible, accurate and reliable solution. This technology not only has high experimental operability, but also lays the foundation for innovative development in clinical applications, diagnosis and treatment of neurological diseases and brain-computer interface technology.

[0021] According to some embodiments of the present invention, the diameter of the fiber core is in the range of 200-800 μm.

[0022] According to some embodiments of the present invention, the cladding layer has a thickness in the range of 10-20 μm.

[0023] According to some embodiments of the present invention, the refractive index of the core is in the range of 1.41-1.42.

[0024] According to some embodiments of the present invention, the refractive index of the cladding is in the range of 1.39-1.40.

[0025] According to some embodiments of the present invention, the material of the flexible base layer includes polyimide.

[0026] In addition to polyimide, other flexible materials can also be used as the substrate.

[0027] According to some embodiments of the present invention, the material of the insulating layer includes polyimide.

[0028] Polyimide, or other insulating materials may be used as the insulating layer.

[0029] According to some embodiments of the present invention, the conductive layer is made of copper.

[0030] According to some embodiments of the present invention, the thickness of the conductive layer is 2 micrometers to 5 micrometers.

[0031] The second aspect of the present invention provides a method for preparing the multi-channel optical fiber neural electrode of the first aspect of the present invention, comprising the following steps:

[0032] S1: preparing a core precursor solution and a cladding precursor solution, injecting the core precursor solution into a mold, and heating and curing the mold to obtain the core;

[0033] S2: Prepare a microelectrode array, apply the cladding precursor solution to the surface of the fiber core, press one side of the flexible substrate layer in the microelectrode array to the surface of the fiber core coated with the cladding solution, heat and cure, and obtain the multi-channel optical fiber neural electrode.

[0034] A technical solution in the method for preparing a multi-channel optical fiber neural electrode of the present invention has at least the following beneficial effects:

[0035] 1. Multi-channel design improves performance: By preparing multi-channel fiber-optic neural electrodes, multiple neural electrical signals can be collected or stimulated at the same time, greatly improving the working efficiency and data collection capabilities of the electrodes. This multi-channel design enables the electrodes to process more signals in neuroscience research and enhances the application potential of electrodes in neural regulation and neural interface technology.

[0036] 2. Fine processing and efficient preparation: This method uses the core precursor solution and the cladding precursor solution, and performs precise curing processes separately to ensure the fine production of the optical fiber structure. By pressing the flexible substrate layer of the microelectrode array with the core surface coated with the cladding solution, the high precision and stability of the electrode are ensured, and the errors and inconsistencies in the process are reduced.

[0037] 3. Structural optimization: The cladding precursor solution is coated on the surface of the fiber core, which helps to form the cladding structure of the optical fiber. This not only improves the light transmission performance of the optical fiber, but also enhances its mechanical matching with the neural tissue, and improves the biocompatibility and long-term stability of the electrode.

[0038] 4. Flexible design improves biocompatibility: The use of a flexible substrate ensures that the multi-channel fiber optic neural electrode can adapt to the bending and expansion of biological tissues, avoiding damage or discomfort of traditional rigid electrodes during implantation. This flexible design enhances the fit between the electrode and the neural tissue, reduces damage to the neural tissue, and improves safety for long-term use.

[0039] 5. Simplify the process and reduce costs: By using a simple precursor solution and a common heating and curing process, this method can reduce production costs while maintaining an efficient preparation process. This makes the technology cost-effective in practical applications and can be promoted and applied on a larger scale.

[0040] Therefore, the preparation method can not only improve the performance and reliability of the multi-channel optical fiber neural electrode, but also optimize the production process, improve the biocompatibility, and have a great practical application prospect. Furthermore, the preparation method of the present invention does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are easily available, the production cost is low, and it is easy to industrialize.

[0041] According to some embodiments of the present invention, the material of the core and the cladding includes polydimethylsiloxane (PDMS).

[0042] According to some embodiments of the present invention, in the core precursor solution, the ratio of the core precursor to the curing agent is 3 to 6:1.

[0043] According to some embodiments of the present invention, in the core precursor solution, the ratio of the core precursor to the curing agent is 3:1, 4:1, 5:1 or 6:1.

[0044] According to some embodiments of the present invention, the core precursor includes polydimethylsiloxane (such as Dow Corning DC184) and its corresponding curing agent.

[0045] According to some embodiments of the present invention, in the cladding precursor solution, the ratio of the cladding precursor to the curing agent is 15 to 25:1.

[0046] According to some embodiments of the present invention, in the cladding precursor solution, the ratio of the cladding precursor to the curing agent is 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1.

[0047] According to some embodiments of the present invention, the cladding precursor includes polydimethylsiloxane (such as Dow Corning DC184) and its corresponding curing agent.

[0048] According to some embodiments of the present invention, the temperature of the heating and curing is 80°C to 100°C.

[0049] According to some embodiments of the present invention, the temperature of the heating and curing is any one of 80°C, 85°C, 90°C, 95°C, 100°C, or a range formed by any two of them, such as 90°C to 95°C.

[0050] According to some embodiments of the present invention, the heating and curing time is 60 to 90 minutes.

[0051] According to some embodiments of the present invention, the method for preparing the microelectrode array comprises the following steps:

[0052] (1) forming a sacrificial layer, the flexible substrate layer and the conductive layer in sequence on a substrate;

[0053] (2) the conductive layer forms a pattern of microelectrode array and interconnection lines by photolithography and wet etching;

[0054] (3) forming an insulating layer on the surface of the conductive layer after the treatment in step S2, and performing patterning by reactive ion etching to expose electrode sites;

[0055] (4) adhering a water-soluble tape to the surface of the insulating layer and picking up the microelectrode array structure from the substrate;

[0056] (5) The microelectrode array structure picked up in step S3 is attached to a substrate, and the water-soluble tape is dissolved with water to form a microelectrode array having a structure of a substrate, an insulating layer, a conductive layer and a flexible base layer in sequence.

[0057] When preparing the flexible optical fiber, the present invention can select other flexible materials, change the preparation conditions according to the different properties of each material, and select a suitable method to prepare the flexible optical fiber.

[0058] When the optical fiber and the microelectrode array are integrated into one, other adhesive substances can be selected to permanently bond the optical fiber and the microelectrode array. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a schematic diagram of sequentially forming a sacrificial layer, a flexible substrate layer and a conductive layer on a substrate.

[0060] Figure 2 It is a schematic diagram of forming a microelectrode array from a conductive layer by photolithography and wet etching.

[0061] Figure 3 It is a schematic diagram of forming an insulating layer on the surface of a conductive layer.

[0062] Figure 4 It is a schematic diagram of the process of patterning by reactive ion etching to expose electrode sites.

[0063] Figure 5Schematic diagram of the process of picking up a microelectrode array structure from a substrate.

[0064] Figure 6 Schematic diagram of the integration of flexible optical fiber and microelectrode array.

[0065] Figure 7 is a cross-sectional diagram of a multi-channel fiber optic neural electrode. DETAILED DESCRIPTION

[0066] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0067] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0068] Unless otherwise specified, "room temperature" in the present invention means 25°C±5°C.

[0069] Unless otherwise specified, "about" in the present invention means that the allowable error is within ±2%.

[0070] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0071] Example

[0072] A multi-channel optical fiber neural electrode was prepared, including an optical fiber substrate and a flexible microelectrode array integrated on the surface of the optical fiber substrate. The optical fiber substrate included a fiber core and a cladding covering the fiber core. The refractive index of the fiber core was greater than that of the cladding. The flexible microelectrode array included a flexible base layer, a conductive layer, and an insulating layer arranged in sequence starting from close to the cladding.

[0073] The diameter of the core is 500 μm and the thickness of the cladding is 10 μm.

[0074] The refractive index of the core is 1.413 and the refractive index of the cladding is 1.390.

[0075] The material of the flexible base layer is polyimide, the material of the insulating layer is polyimide, and the material of the conductive layer is copper.

[0076] The thickness of the conductive layer is 3 microns.

[0077] The specific preparation method is:

[0078] S1: preparing a core precursor solution and a cladding precursor solution, injecting the core precursor solution into a mold, and heating and curing the solution to obtain a core;

[0079] S2: Prepare a microelectrode array, apply a cladding precursor solution to the core surface, press one side of the flexible substrate layer in the microelectrode array to the core surface coated with the cladding solution, heat and cure, and obtain a multi-channel optical fiber neural electrode.

[0080] In step S1:

[0081] In the core precursor solution, the ratio of the core precursor to the curing agent is 5:1.

[0082] The fiber core precursor is polydimethylsiloxane (Dow Corning DC184) and its curing agent.

[0083] In the cladding precursor solution, the ratio of the cladding precursor to the curing agent is 20:1.

[0084] The cladding precursor is polydimethylsiloxane (Dow Corning DC184) and its curing agent.

[0085] The temperature of heating and curing is 90°C, and the time of heating and curing is 60 minutes.

[0086] In step S2:

[0087] The preparation method of the microelectrode array is specifically as follows:

[0088] (1) forming a sacrificial layer, a flexible base layer and a conductive layer on a substrate in sequence:

[0089] like Figure 1 As shown, a PDMS layer is first spin-coated on a glass substrate to bond with the glass and serve as a "sacrificial layer" during the transfer of the microelectrode array. A polyimide layer is attached to the PDMS layer to serve as a flexible substrate for the microelectrode array, and then a copper foil is attached as a conductive layer with a film thickness of about 3 μm.

[0090] (2) Figure 2 As shown, the conductive layer is patterned into microelectrode arrays and interconnect lines by photolithography and wet etching.

[0091] (3) Figure 3 As shown, an insulating layer is formed on the surface of the conductive layer after being processed in step S2. Figure 4 As shown, patterning is performed by reactive ion etching to expose electrode sites;

[0092] (4) Figure 5 As shown in step a, a water-soluble tape is adhered to the surface of the insulating layer, and the microelectrode array structure is picked up from the substrate;

[0093] (5) Figure 5 As shown in step b in step S3, the microelectrode array structure picked up in step S3 is attached to the substrate, as shown in step b in step S3. Figure 5 As shown in step c, after the water-soluble tape is dissolved with water, a microelectrode array having a structure of a substrate, an insulating layer, a conductive layer and a flexible base layer is formed.

[0094] After the microelectrode array is prepared, the cladding precursor solution is coated on the core surface, and one side of the flexible substrate layer in the microelectrode array is pressed onto the core surface coated with the cladding solution, such as Figure 6 As shown, after heating and curing, the obtained multi-channel optical fiber neural electrode has a cross-sectional view as shown Figure 7 shown.

[0095] It should be noted that the core innovation of the technical solution of the present invention is that by integrating a flexible microelectrode array on the surface of the optical fiber substrate, multiple electrodes can be simultaneously contacted with different nerve areas to perform multi-point electrical signal recording. Unlike the prior art, this design overcomes the limitations of previous microwire integration or silver nanowire coating electrodes, and can effectively expand the number of recording channels and improve the spatial resolution of the signal. This has great application potential for complex neural network research, pathological research, and neural interface technology.

[0096] Furthermore, the flexibility and lightness of the optical fiber matrix of the present invention significantly improves its adaptability during the neural electrode implantation process. The flexible design enables the optical fiber to be easily bent to adapt to the complex morphology and position of the neural tissue, while reducing the biological damage caused by the relative movement between the hardware and the brain tissue during the implantation process. Compared with traditional rigid optical fibers or electrodes, flexible optical fibers can reduce mechanical pressure and damage to brain tissue, thereby reducing the risk of inducing inflammatory reactions and rejection reactions.

[0097] Furthermore, the difference in refractive index between the core part (core) and the cladding of the optical fiber of the present invention ensures that the optical signal is efficiently transmitted inside the optical fiber through the principle of total internal reflection. When the optical signal passes through the optical fiber, the light that meets a certain angle will be totally reflected at the interface between the core and the cladding, avoiding the leakage of the optical signal. This feature ensures the transmission efficiency of the optical signal in the application of neural electrodes and provides stable and accurate optogenetic stimulation capabilities.

[0098] It should also be noted that, unlike the common method of integrating electrodes by metal wire or solution deposition in the prior art, the present invention adopts an integrated design to directly construct a flexible microelectrode array on the surface of the optical fiber substrate. The array is composed of a flexible substrate layer, a conductive layer and an insulating layer in sequence, which can ensure good electrical signal transmission and avoid electrical interference between different electrodes. The flexible substrate provides good mechanical adaptability for the electrode, enabling it to better contact with neural tissue and maintain stable signal acquisition performance with brain tissue or peripheral neural structure.

[0099] Another significant advantage of the multi-channel fiber optic neural electrode solution of the present invention is its excellent biocompatibility. The use of flexible materials can not only better adapt to the curves and surface characteristics of neural tissue, but also reduce mechanical damage during implantation. In addition, this design also reduces the biological rejection caused by mechanical friction between hard implants and brain tissue. Compared with rigid electrodes, flexible electrodes have better long-term implant stability and can continuously provide high-quality electrical signal recordings. In addition to electrical signal acquisition, the fiber optic neural electrode of the present invention also has the ability to transmit optical signals, and can provide optogenetic stimulation while performing electrophysiological recordings. This photoelectric coupling function provides a wider range of experimental means for neuroscience research. Researchers can achieve optogenetic control and electrophysiological monitoring on the same device at the same time, providing more accurate regulation and analysis of neural electrical activity. Since optical fiber can achieve accurate light transmission, combined with multi-channel electrical signal acquisition capabilities, this neural electrode can better cooperate with modern neural regulation technologies (such as optogenetics) to perform high-precision experimental design and control. By performing fine light stimulation in specific areas and monitoring multi-point electrical activity in real time, the accuracy and repeatability of neural activity research can be greatly improved. The multi-channel optical fiber neural electrode of the present invention can be widely used in various neuroscience research fields, especially in optogenetics research, neural interface, brain-computer interface (BCI), electroencephalogram (EEG) and peripheral nerve monitoring, etc. It can provide more advanced and efficient experimental tools for these fields and provide new breakthroughs for scientific research and clinical treatment.

[0100] The present invention has been described in detail above in conjunction with the embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A multi-channel optical fiber neural electrode, characterized in that: The invention comprises an optical fiber substrate and a flexible microelectrode array integrated on the surface of the optical fiber substrate, wherein the optical fiber substrate comprises a fiber core and a cladding covering the fiber core, the refractive index of the fiber core is greater than the refractive index of the cladding, and the flexible microelectrode array comprises a flexible base layer, a conductive layer and an insulating layer which are sequentially arranged starting from the vicinity of the cladding.

2. The multi-channel optical fiber neural electrode according to claim 1, characterized in that: The diameter of the core is in the range of 200-800 μm; and / or the thickness of the cladding is in the range of 10-20 μm.

3. The multi-channel optical fiber neural electrode according to claim 1, characterized in that: The refractive index of the core is in the range of 1.41-1.42; and / or the refractive index of the cladding is in the range of 1.39-1.

40.

4. The multi-channel optical fiber neural electrode according to claim 1, characterized in that: The material of the flexible base layer includes polyimide; and / or the material of the insulating layer includes polyimide.

5. The multi-channel optical fiber neural electrode according to claim 1, characterized in that: The conductive layer is made of copper; and / or the conductive layer has a thickness of 2 micrometers to 5 micrometers.

6. A method for preparing a multi-channel optical fiber neural electrode as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: preparing a core precursor solution and a cladding precursor solution, injecting the core precursor solution into a mold, and heating and curing the mold to obtain the core; S2: Prepare a flexible microelectrode array, apply the cladding precursor solution to the surface of the fiber core, press one side of the flexible base layer in the flexible microelectrode array to the surface of the fiber core coated with the cladding solution, heat and cure, and obtain the multi-channel optical fiber neural electrode.

7. The method according to claim 6, characterized in that In the core precursor solution, the ratio of the core precursor to the curing agent is 3-6:1; and / or the core precursor includes polydimethylsiloxane.

8. The method according to claim 6, characterized in that In the cladding precursor solution, the ratio of the cladding precursor to the curing agent is 15-25:1; and / or the cladding precursor includes polydimethylsiloxane.

9. The method according to claim 6, characterized in that The temperature of the heating and curing is 80° C. to 100° C.; and / or the time of the heating and curing is 60 to 90 minutes.

10. The method according to any one of claims 6 to 9, characterized in that The method for preparing the flexible microelectrode array comprises the following steps: (1) forming a sacrificial layer, the flexible substrate layer and the conductive layer in sequence on a substrate; (2) The conductive layer forms a pattern of a flexible microelectrode array and interconnection lines by photolithography and wet etching; (3) forming an insulating layer on the surface of the conductive layer after the treatment in step S2, and performing patterning by reactive ion etching to expose electrode sites; (4) adhering a water-soluble tape to the surface of the insulating layer and picking up the flexible microelectrode array structure from the substrate; (5) The microelectrode array structure picked up in step S3 is attached to a substrate, and the water-soluble tape is dissolved with water to form a flexible microelectrode array having a structure of a substrate, an insulating layer, a conductive layer and a flexible base layer in sequence.

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