Multi-channel flexible neural microelectrode and preparation method thereof

Abstract

The invention relates to a preparation method of a multichannel neural microelectrode, which comprises the following steps of: S1, curing on the upper surface of a PET (Polyethylene Terephthalate) base film to form a photoresist coating and a plurality of slender deposition tanks for later use; s2, graphene deposition layers are respectively formed on the upper surface of the photoresist coating of the PET base film and in the deposition grooves by using a magnetron sputtering method, then the photoresist coating is stripped and removed, the graphene deposition layers in the deposition grooves are reserved to form slender graphene microfilaments, and the slender graphene microfilaments are dried for later use after being cleaned; and S3, covering a waterproof film, performing hot-pressing bonding, reserving a plurality of measuring holes for exposing the graphene microfilaments at one end of the waterproof film corresponding to the graphene microfilaments, and finally punching and puncturing an area avoiding the graphene microfilaments to form wetting holes. The preparation method has the advantages that a plurality of micron-sized graphene microfilaments with regular and controllable shapes are formed on the surface of the flexible base membrane at one time by a photoetching machine and a magnetron sputtering technology, the microelectrode product is obtained after the waterproof membrane is covered, the biocompatibility is good, and the preparation method is simple, efficient and low in cost.

Description

Technical Field

[0001] The present invention relates to the field of neural sensor devices, and in particular to a multi-channel neural microelectrode and a preparation method thereof. Background Art

[0002] Neural microelectrodes are a type of sensor device that works by converting bioelectric signals into universal electrical signals. Neural microelectrodes can be implanted into neural tissue to record and stimulate neuronal activity. By measuring the pulse activity or potential changes of neurons, the function and pathophysiological characteristics of neural networks can be studied. In addition, when neural microelectrodes are implanted into the brain area, they can capture brain activity signals, act as a brain-computer interface, and convert brain activity signals into commands to control external devices, thereby achieving limb control for paralyzed patients.

[0003] Metal microwire electrodes are currently the most widely used neural microelectrodes. In order to ensure the electrode's sensitivity to signals and reduce damage to human tissue, precious metals such as gold, platinum, and iridium are usually used as electrode materials. Since metal microwire electrodes require the diameter of the electrode tip to be very small, generally less than 100μm, the processing of metal microwire electrodes is relatively difficult. In particular, when multi-channel signal acquisition is required for multiple detection points, multiple metal microwires must be separately coated with an insulating layer and then integrated together, which makes the processing more difficult and leads to higher product production costs. In addition, the flexibility and biocompatibility of metal microwire electrodes also limit their wider promotion and use to a certain extent. Summary of the invention

[0004] The present invention provides a multi-channel neural microelectrode and a preparation method thereof, aiming to overcome the shortcomings of metal microwire electrode products prepared with precious metals such as gold, platinum, iridium, etc. as electrode materials in the prior art, such as high cost, poor flexibility and biocompatibility.

[0005] The technical solution of the present invention to solve the above technical problem is as follows: a method for preparing a multi-channel neural microelectrode, which comprises the following steps:

[0006] S1. First, the upper surface of the PET base film is cleaned with oxygen plasma, and then the photoresist is spin-coated and cured. Then, in the presence of a patterned photomask, the photoresist coating is developed using a photolithography machine, and then the photoresist that is easily soluble after light exposure is washed away with a cleaning solvent. A plurality of elongated deposition grooves are formed on the cured photoresist coating on the upper surface of the PET base film, and then dried for standby use;

[0007] S2. forming graphene deposition layers on the upper surface of the photoresist coating of the PET base film and in the deposition tanks respectively by magnetron sputtering, and then placing in a stripping solution to strip off the solidified photoresist coating, the graphene deposition layer originally attached to the upper surface of the photoresist coating loses its load and enters the stripping solution, and the graphene deposition layer in each deposition tank is retained to form elongated graphene microfilaments due to its close connection with the PET base film, and after washing for multiple times, drying and standby;

[0008] S3. Cover the upper surface with a layer of waterproof film, and heat press the waterproof film to bond it to the PET base film. The waterproof film is provided with a plurality of measuring holes for exposing the graphene microfilaments at one end corresponding to the graphene microfilaments. Finally, a punching device with a punching needle is used to punch and puncture the film in an area avoiding the graphene microfilaments to form wetting holes.

[0009] On the basis of the above technical solutions, the present invention may further have the following specific options or more preferred options.

[0010] Specifically, light-transmitting gaps corresponding to the deposition grooves are formed on the patterned photomask in S1.

[0011] Specifically, the thickness of the photoresist coating in S1 is 30-60 μm.

[0012] Specifically, the cleaning solvent in S1 is ethanol or acetone.

[0013] Specifically, the width of the deposition groove in S1 is 10-30 μm, and the length is 5-12 cm.

[0014] Specifically, the stripping solution in S2 is 8-12 wt % sodium hydroxide solution.

[0015] Specifically, the waterproof film in S3 is a PET film, a PI film, a PVC film or a HDPE film.

[0016] Specifically, the diameter of the measuring hole in S3 is 30-40 μm, and the diameter of the wetting hole is 50-100 μm.

[0017] Specifically, the graphene microfilaments are parallel to each other and spaced apart, and the spacing between two adjacent graphene microfilaments is 100-300 μm. The periphery of the PET base film is provided with a circle of punching areas for forming the wetting holes.

[0018] The present invention also provides a multi-channel neural microelectrode, which is prepared by the above method.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention first coats photoresist on the surface of a PET base film, then forms a solidified photoresist coating with a plurality of deposition grooves on the surface of the PET base film by using a photolithography machine, then forms a graphene deposition layer by magnetron sputtering, and then removes the solidified photoresist coating by washing to form graphene microfilaments with a size of micrometer level and a relatively regular and controllable shape on the PET base film, and finally hot presses and bonds a waterproof film on the surface layer and punches and punctures to form wetting holes, so as to obtain a multi-channel neural microelectrode with excellent flexibility, conductivity and the like. The graphene has excellent conductivity and good biocompatibility and will not damage the contacted neural tissue. The presence of the wetting holes can ensure that both sides of the electrode film body are more easily wetted by tissue fluid, so as to ensure that the electrode film can be better compatible with the tissue after being implanted in the human body; and at the same time, the photolithography and magnetron sputtering technologies are combined, so that graphene microfilaments with a micrometer scale and controllable shape can be produced more conveniently, and the controllability and precision are higher than those of producing metal microfilament neural electrodes, and the multi-channel electrodes can be produced more easily and at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A front view of a multi-channel flexible neural microelectrode provided by the present invention;

[0022] Figure 2 for Figure 1 The cross-sectional view of the multi-channel flexible neural microelectrode along AA is shown;

[0023] Figure 3 for Figure 1 The front view of the PET base film after the photolithography machine is processed to form a cured photoresist coating and a deposition groove during the preparation process of the multi-channel flexible neural microelectrode shown;

[0024] Figure 4 for Figure 3 A cross-sectional view of the structure shown along BB;

[0025] Figure 5 for Figure 3 Cross-sectional view of the structure shown after graphene microfilaments are formed by surface magnetron sputtering.

[0026] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0027] 1. PET base film; 2. Graphene microfilaments; 3. Waterproof film; 4. Measuring hole; 5. Wetting hole;

[0028] 6. Photoresist coating; 7. Deposition tank; 8. Graphene deposition layer. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] To avoid redundant description, the pharmaceutical raw materials used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified.

[0031] In the following embodiments, the target material used in the magnetron sputtering method for depositing the graphene deposition layer is a graphene carbon target. The graphene carbon target is prepared by a series of treatments such as mixing graphene and ethylene glycol in a certain proportion, drying, and pressurizing. The preparation process of the graphene carbon target adopts the existing technology and is not described here. Argon is used as the diluent gas during magnetron sputtering, the gas pressure is adjusted to 0.9-1.5Pa, the sputtering current is 1.2-1.5A, and the deposition treatment is 8-15h.

[0032] It should be noted that if Figure 1 and 2 As shown, the multi-channel neural microelectrode provided by the present invention has a PET base film 1, a graphene microwire 2, a waterproof film 3, a measuring hole 4 and a wetting hole 5, and an intermediate transition structure formed during the preparation process, such as Figures 3 to 5 As shown, it includes a photoresist coating 6, a deposition groove 7 and a graphene deposition layer 8.

[0033] Example 1

[0034] A multi-channel neural microelectrode, the preparation method of which comprises the following steps:

[0035] S1. First, the upper surface of the PET base film is cleaned with oxygen plasma, and then a photoresist is spin-coated and cured. The thickness of the photoresist coating is 50 μm. In the presence of a patterned photomask (having a plurality of light-transmitting gaps arranged at intervals), the photoresist coating is developed using a photolithography machine, and then ethanol is rinsed multiple times to remove the photoresist dissolved by light. Then, a plurality of elongated deposition grooves with a width of 25 μm and a length of 8 cm are formed on the photoresist coating on the upper surface of the PET base film, and the coating is dried for standby use;

[0036] S2. Use magnetron sputtering to form graphene deposition layers on the upper surface of the photoresist coating of the PET base film and in the deposition tank, respectively, and then place it in a 10wt% sodium hydroxide solution (stripping solution) to strip off the solidified photoresist coating. The graphene deposition layer originally attached to the upper surface of the photoresist coating loses its load and enters the stripping solution. The graphene deposition layer in each deposition tank is closely connected with the PET base film and is retained to form elongated graphene microfilaments with a thickness of 4μm, a width of 25μm, and a length of 8cm. After the entire film is washed several times, it is dried and set aside;

[0037] S3. Cover the upper surface with a layer of PET waterproof film, and hot press to bond the waterproof film to the PET base film. The waterproof film is provided with a plurality of measuring holes for exposing the graphene microfilaments at one end corresponding to the graphene microfilaments, and the diameter of the measuring holes is 32 μm. Finally, a punching device with a punching needle is used to punch and puncture the area on the membrane avoiding the graphene microfilaments to form wetting holes with a diameter of 65 μm.

[0038] Example 2

[0039] A multi-channel neural microelectrode, the preparation method of which comprises the following steps:

[0040] S1. First, the upper surface of the PET base film is cleaned with oxygen plasma, and then a photoresist is spin-coated and cured. The thickness of the photoresist coating is 30 μm. In the presence of a patterned photomask (having a plurality of light-transmitting gaps arranged at intervals), the photoresist coating is developed using a photolithography machine, and then the photoresist whose solubility is enhanced by light is washed with ethanol for multiple times to remove the photoresist. Then, a plurality of elongated deposition grooves with a width of 10 μm and a length of 5 cm are formed on the photoresist coating cured on the upper surface of the PET base film, and the coating is dried for standby use;

[0041] S2. Use magnetron sputtering to form graphene deposition layers on the upper surface of the photoresist coating of the PET base film and in the deposition tank, respectively, and then place it in an 8wt% sodium hydroxide solution (stripping solution) to strip off the solidified photoresist coating. The graphene deposition layer originally attached to the upper surface of the photoresist coating loses its load and enters the stripping solution. The graphene deposition layer in each deposition tank is closely connected to the PET base film and is retained to form elongated graphene microfilaments with a thickness of 1μm, a width of 10μm, and a length of 5cm. After the entire film is washed several times, it is dried and set aside;

[0042] S3. Cover the upper surface with a layer of PET waterproof film, and heat press the waterproof film to bond it to the PET base film. The waterproof film is provided with a plurality of measuring holes for exposing the graphene microfilaments at one end corresponding to the graphene microfilaments, and the diameter of the measuring holes is 30 μm. Finally, a punching device with a punching needle is used to punch and puncture the area on the membrane avoiding the graphene microfilaments to form wetting holes with a diameter of 50 μm.

[0043] Example 3

[0044] A multi-channel neural microelectrode, the preparation method of which comprises the following steps:

[0045] S1. First, the upper surface of the PET base film is cleaned with oxygen plasma, and then a photoresist is spin-coated and cured. The thickness of the photoresist coating is 60 μm. In the presence of a patterned photomask (having a plurality of light-transmitting gaps arranged at intervals), the photoresist coating is developed using a photolithography machine, and then the photoresist whose solubility is enhanced by light is washed with ethanol for multiple times to remove. Then, a plurality of elongated deposition grooves with a width of 30 μm and a length of 12 cm are formed on the photoresist coating on the upper surface of the PET base film, and the coating is dried for standby use;

[0046] S2. Use magnetron sputtering to form graphene deposition layers on the upper surface of the photoresist coating of the PET base film and in the deposition tank, respectively, and then place it in a 12wt% sodium hydroxide solution (stripping solution) to strip off the solidified photoresist coating. The graphene deposition layer originally attached to the upper surface of the photoresist coating loses its load and enters the stripping solution. The graphene deposition layer in each deposition tank is closely connected to the PET base film and is retained to form elongated graphene microfilaments with a thickness of 6μm, a width of 30μm, and a length of 12cm. After the entire film is washed several times, it is dried and set aside;

[0047] S3. Cover the upper surface with a layer of PET waterproof film, and hot press to bond the waterproof film to the PET base film. The waterproof film is provided with a plurality of measuring holes for exposing the graphene microfilaments at one end corresponding to the graphene microfilaments, and the diameter of the measuring holes is 40μm. Finally, a punching device with a punching needle is used to punch and puncture the area on the film avoiding the graphene microfilaments to form wetting holes with a diameter of 100μm.

[0048] It should be noted that the photoresist used in the above embodiments is a positive photoresist, that is, the solubility of the exposed area of ​​the cured coating increases, and the desired pattern structure is displayed by washing away the dissolved area exposed to light. The multi-channel flexible neural microelectrodes prepared in the above embodiments can be implanted in human tissue when used, each measuring hole is close to the tissue and the exposed graphene microfilaments are in contact with the neuronal cells of the tissue, and the other end of each graphene microfilament is connected to the data acquisition device through an electrode line.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a multi-channel neural microelectrode, characterized in that: The steps include: S1. First, the upper surface of the PET base film is cleaned with oxygen plasma, and then the photoresist is spin-coated and cured. Then, in the presence of a patterned photomask, the photoresist coating is developed using a photolithography machine, and then the photoresist that is easily soluble after light exposure is washed away with a cleaning solvent. A plurality of elongated deposition grooves are formed on the cured photoresist coating on the upper surface of the PET base film, and then dried for standby use; S2. forming graphene deposition layers on the upper surface of the photoresist coating of the PET base film and in the deposition tanks respectively by magnetron sputtering, and then placing in a stripping solution to strip off the solidified photoresist coating, the graphene deposition layer originally attached to the upper surface of the photoresist coating loses its load and enters the stripping solution, and the graphene deposition layer in each deposition tank is retained to form elongated graphene microfilaments due to its close connection with the PET base film, and after washing for multiple times, drying and standby; S3. Cover the upper surface with a layer of waterproof film, and heat press the waterproof film to bond it to the PET base film. The waterproof film is provided with a plurality of measuring holes for exposing the graphene microfilaments at one end corresponding to the graphene microfilaments. Finally, a punching device with a punching needle is used to punch and puncture the film in an area avoiding the graphene microfilaments to form wetting holes.

2. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The patterned photomask in S1 is formed with light-transmitting gaps corresponding to the deposition grooves.

3. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The thickness of the photoresist coating in S1 is 30-60 μm.

4. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The cleaning solvent in S1 is ethanol or acetone.

5. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The width of the deposition groove in S1 is 10-30 μm and the length is 5-12 cm.

6. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The stripping liquid in S2 is 8-12 wt % sodium hydroxide solution.

7. The method for preparing a multi-channel neural microelectrode according to claim 1, characterized in that: The waterproof film in S3 is a PET film, a PI film, a PVC film or a HDPE film.

8. A method for preparing a multi-channel neural microelectrode according to claims 1 to 7, characterized in that: The diameter of the measuring hole in S3 is 30-40 μm, and the diameter of the wetting hole is 50-100 μm.

9. The method for preparing a multi-channel neural microelectrode according to claim 8, characterized in that: The graphene microfilaments are parallel to each other and spaced apart, and the spacing between two adjacent graphene microfilaments is 100-300 μm. The outer periphery of the PET base film is provided with a circle of punching areas for forming the wetting holes.

10. A multi-channel neural microelectrode, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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