Graphene hydrogel neural microelectrode and preparation method thereof
By using a graphene hydrogel conductive expansion layer in the neural microelectrode and loading amino multi-walled carbon nanotubes and gold nanoparticles, the problem of poor contact between the neural microelectrode and the neural tissue is solved, good contact and conductive performance are achieved, while reducing the inflammatory response and improving flexibility.
Patent Information
- Application Number
- CN202510765944.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-09-05
AI Technical Summary
The electrode contacts of existing neural microelectrodes have poor contact with neural tissue, are complex in structure and easily damage neural tissue, are cumbersome to operate, and have poor flexibility.
Graphene hydrogel is used as the conductive expansion layer, loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots and gold nanoparticles, and electrode contacts are formed through thermal or water absorption expansion. Combined with the insulating base and covering layer design, good contact is ensured.
Good contact between the neural microelectrode and the neural tissue is achieved, the conductivity is maintained, the inflammatory response is reduced, and the flexibility and ease of operation are improved.
Smart Images
Figure CN120586273A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of neural microelectrodes and flexible electronic devices, and in particular relates to a graphene hydrogel neural microelectrode and a preparation method thereof. Background Art
[0002] As a key interface between neural tissue and functional devices, neural microelectrodes play an important role in treating neurological diseases such as paraplegia, Parkinson's disease, optic nerve damage, and auditory nerve damage. Through electrical stimulation, neural microelectrodes can excite nerve cells and generate action potentials, thereby creating an effective neural bypass for patients with nerve damage and promoting the recovery of corresponding functions.
[0003] In order for a neural microelectrode to achieve its function, it must ensure that its electrode contacts are in good contact with the neural tissue to provide electrical stimulation to the neural tissue. In the prior art, in order to ensure that the electrode contacts of the neural microelectrode can better contact the neural tissue, a special structural design is generally required to make the electrode contacts protrude outward relative to the plane of the neural electrode body to form a protrusion. For example, a corresponding special structural design reported in a study is to form a closed cavity below the electrode contact in the microelectrode body, and then inject liquid into the closed cavity to make the electrode contact protrude outward or add a thermosensitive swelling hydrogel during the formation so that the electrode contact protrudes outward due to temperature-sensitive expansion. The above-mentioned closed cavity injection method has technical problems such as complex structure, cumbersome operation and inaccurate relative position of the electrode contacts; the method of inserting a thermosensitive swelling hydrogel into the closed cavity has the problem of requiring a base layer with a large elastic modulus, which will significantly reduce the flexibility of the microelectrode and thus easily damage the neural tissue. At the same time, the matching serpentine electrode that can extend with the expansion effect is difficult to operate, and the operation of inserting the hydrogel into the closed cavity is also difficult. Therefore, it is necessary to provide a new special structure to ensure the formation of the protrusion so as to achieve good contact between the electrode contact and the nerve tissue. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a graphene hydrogel neural microelectrode and a preparation method thereof, aiming to overcome the above-mentioned deficiencies in the prior art.
[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a graphene hydrogel neural microelectrode, comprising an elongated electrode body, wherein the electrode body comprises an insulating base layer, a conductive layer and an insulating covering layer, wherein the conductive layer is wrapped and sealed by the insulating base layer and the insulating covering layer, and the insulating covering layer is provided with a contact window at one end near the electrode body, and a conductive expansion layer composed of graphene hydrogel is provided below the insulating covering layer in and around the contact window, wherein the conductive expansion layer is electrically connected to the conductive layer, and the conductive expansion layer can expand after being heated or absorbing water to form an electrode contact protruding outward from the contact window, and the graphene hydrogel is loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots and gold nanoparticles.
[0006] On the basis of the above technical solutions, the present invention may further have the following specific options or more preferred options.
[0007] Specifically, the graphene hydrogel is prepared by the following method: Low-viscosity chitosan and acetic acid solution are fully stirred to obtain solution one, amino multi-walled carbon nanotubes and amino graphene quantum dot powders are added to solution one at room temperature, and the mixture is fully stirred to obtain solution two, tetrachloroauric acid is added to solution two under light-shielding conditions, and the mixture is fully stirred to obtain solution three, the temperature is raised to 35-40° C., glutaraldehyde is added to solution three, and the mixture is slowly stirred to perform cross-linking and reduction reactions, and after sufficient reaction, the mixture is filtered, washed with water, and naturally dried to a water content of less than 10%, thereby obtaining the graphene hydrogel loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots, and gold nanoparticles.
[0008] Specifically, solution 1 is prepared by mixing low-viscosity chitosan with a viscosity of 120-200 mPa.s and an acetic acid solution with a volume concentration of 1.8-2.2% in a ratio of 8-12 mg:1 mL.
[0009] Specifically, the mass ratio of amino multi-walled carbon nanotubes and amino graphene quantum dot powder is 1.5-2.5:1, the dosage ratio of amino graphene quantum dot powder to solution one is 0.8-1 mg:2.5 mL, the mass ratio of tetrachloroauric acid to amino graphene quantum dot powder is 5-8:1, and the volume ratio of glutaraldehyde to solution three is 1:4-6.
[0010] Specifically, the ratio of the area of the contact window to the coverage area of the conductive expansion layer is 1:2-5.
[0011] Specifically, the number of the contact windows is one or a plurality of contact windows arranged at intervals.
[0012] Preferably, the contact window is circular or rectangular.
[0013] Specifically, the insulating base layer and the insulating cover layer are both PI films or Parylene films with a thickness of 1-15 μm.
[0014] Preferably, the metal material of the conductive layer is gold or platinum, and the thickness is 0.1-1 μm.
[0015] The present invention also provides a method for preparing the above-mentioned graphene hydrogel neural microelectrode, which comprises the following steps: S1. Use a vacuum thermal evaporation coating machine to deposit a layer of PI film or Parylene film on the substrate as an insulating base layer; S2. Depositing a layer of gold or platinum on the insulating base layer to form a metal layer, coating the metal layer with a positive photoresist, patterning the photoresist using a planar photolithography technique to obtain a photoresist mask, and then using a wet etching technique to remove excess portions of the metal layer to obtain a conductive layer; S3. Printing or coating a fully wetted graphene hydrogel in the area corresponding to one end of the conductive layer and the preset electrode contact, and drying it naturally to obtain a conductive expansion layer; S4. Use the vacuum thermal evaporation coating machine again to deposit a layer of PI film or Parylene film covering the insulating base layer, the conductive layer, and the conductive expansion layer as the insulating covering layer. Use reactive ion etching technology to open contact windows in the areas corresponding to the electrode contacts on the insulating covering layer to expose the central area of the conductive expansion layer.
[0016] Compared with the prior art, the present invention has the following beneficial effects: The neural microelectrode provided by the present invention utilizes a graphene hydrogel, which expands upon exposure to heat or water and has excellent conductivity, as a conductive expansion layer to effectively contact neural tissue. Upon absorbing water or exposure to heat, the conductive expansion layer expands, protruding outward from the contact window to form an effective electrode contact higher than the insulating covering layer, thereby ensuring better contact with neural tissue. Because the surface and interior of the graphene hydrogel are loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots, and gold nanoparticles, the graphene hydrogel, which serves as a conductive contact, maintains good conductivity after expansion to effectively transmit electrical signals. Furthermore, its three-dimensional network structure, primarily composed of chitosan, is rich in amino and hydroxyl groups on the surface, resulting in excellent tissue affinity. Compared to traditional metal conductive contacts, the graphene hydrogel, primarily composed of chitosan, also has a natural antibacterial effect, reducing the probability of inflammation and immune response. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A schematic diagram of the structure of a graphene hydrogel neural microelectrode provided by the present invention; Figure 2 for Figure 1 The cross-sectional view of the neural microelectrode along AA is shown; Figure 3 for Figure 2 Schematic diagram of the conductive expansion layer of the neural microelectrode after it expands when heated or absorbs water; Figure 4 A schematic diagram of another structure of a graphene hydrogel neural microelectrode provided by the present invention, wherein a plurality of circular contact windows are spaced apart at one end of the electrode contact; Figure 5 for Figure 4 The cross-sectional view of the neural microelectrode along the BB is shown; Figure 6 This is a schematic diagram of another structure of a graphene hydrogel neural microelectrode provided by the present invention, which has multiple rectangular contact windows spaced apart at one end of the electrode contact.
[0018] In the accompanying drawings, the components represented by the reference numerals are as follows: 1. Electrode body; 2. Insulating base layer; 3. Conductive layer; 4. Insulating cover layer; 5. Contact window; 6. Conductive expansion layer. DETAILED DESCRIPTION
[0019] The principles and features of the present invention are further described in detail below with reference to 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.
[0020] In the description of the present invention, if terms indicating directions such as "up", "down", "left", "right", "top", "bottom", "inside" and "outside" are used, the directions or positional relationships indicated are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, they should not be understood as limiting the present invention.
[0021] To avoid redundancy, the drugs 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.
[0022] The graphene hydrogel used in the present invention is prepared by the following method: low-viscosity chitosan and acetic acid solution are fully stirred to obtain solution one, specifically, solution one is prepared by mixing low-viscosity chitosan with a viscosity of 120-200 mPa.s with an acetic acid solution with a volume concentration of 1.8-2.2% in a ratio of 8-12 mg:1 mL; after obtaining solution one, amino multi-walled carbon nanotubes and amino graphene quantum dot powder are added to solution one at room temperature, and the mixture is fully stirred to obtain solution two, tetrachloroauric acid is added to solution two under light-shielding conditions, and the mixture is fully stirred to obtain solution three, and the mixture is heated to 35-40°C and stirred to obtain solution three. Glutaraldehyde is added to solution three and slowly stirred to perform crosslinking and reduction reactions. After sufficient reaction, the solution is filtered, washed with water, and naturally dried to a water content of less than 10%, thereby obtaining the graphene hydrogel loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots, and gold nanoparticles. The mass ratio of amino multi-walled carbon nanotubes and amino graphene quantum dot powders is 1.5-2.5:1, the amount ratio of amino graphene quantum dot powder to solution one is 0.8-1 mg:2.5 mL, the mass ratio of tetrachloroauric acid to amino graphene quantum dot powder is 5-8:1, and the volume ratio of glutaraldehyde to solution three is 1:4-6.
[0023] Preferably, the graphene hydrogels used in the following embodiments are all prepared by the following specific method: 25 mg of CS (low viscosity chitosan, viscosity of about 165 mPa.s) and 2.5 mL of 2% acetic acid solution are mixed and stirred at room temperature for 2 h to obtain solution one, 2 mg of amino multi-walled carbon nanotubes and 1 mg of amino graphene quantum dot powder are added to solution one and stirred uniformly to obtain solution two; 7.87 mg of HAuCl4 (chloroauric acid) is dissolved in solution two under low temperature and light protection conditions, and stirred thoroughly until HAuCl4 is dissolved to obtain solution three; the temperature is raised to 35°C, 0.5 mL of GA (glutaraldehyde) is added to solution three, and 5 min later, the CS, amino multi-walled carbon nanotubes and amino graphene quantum dots in the system were fully cross-linked by GA. At the same time, under the reducing action of GA, HAuCl4 was gradually reduced to AuNPs (gold nanoparticles). After filtration, washing and natural drying to a water content of less than 10%, a graphene hydrogel with excellent conductive properties was obtained. The graphene hydrogel was loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots and gold nanoparticles.
[0024] It should be noted that the water content of the graphene hydrogel after natural drying is below 10%. Testing has shown that it has excellent conductive properties. After fully absorbing water, the water content can reach about 25% and it expands significantly. After fully absorbing water, it still maintains good conductivity. Example
[0025] The present invention provides a graphene hydrogel neural microelectrode, such as Figures 1 to 2As shown, it includes a long strip of electrode body 1, which includes an insulating base layer 2 (Parylene film, thickness 5μm), a conductive layer 3 (nano-gold layer, thickness 200nm) and an insulating cover layer 4 (Parylene film, thickness 5μm). The conductive layer 3 is wrapped and sealed by the insulating base layer and the insulating cover layer 4. The insulating cover layer 4 has a circular contact window 5 at one end near the electrode body 1. A conductive expansion layer 6 (thickness of about 20μm) composed of graphene hydrogel is provided under the insulating cover layer 4 in and around the contact window 5. The ratio of the area of the contact window 5 to the coverage area of the conductive expansion layer 6 is approximately 1:5. The conductive expansion layer 6 is electrically connected to the conductive layer 3, as shown in FIG. Figure 3 As shown, the conductive expansion layer 6 can expand after being heated or absorbing water in the body to form electrode contacts protruding outward from the contact window 5.
[0026] Example 2 The present invention provides a graphene hydrogel neural microelectrode, which includes a long strip electrode body 1, the electrode body 1 includes an insulating base layer 2 (Parylene film, thickness 5μm), a conductive layer 3 (nano-gold layer, thickness 200nm) and an insulating cover layer 4 (Parylene film, thickness 5μm), the conductive layer 3 is wrapped and sealed by the insulating base layer and the insulating cover layer 4, and the insulating cover layer 4 is provided with a plurality of circular contact windows 5 (such as Figure 4 As shown in FIG5 ), a conductive expansion layer 6 (circular and about 25 μm thick) made of graphene hydrogel is provided below the insulating cover layer 4 in and around the contact window 5. The ratio of the total area of the contact window 5 to the coverage area of the conductive expansion layer 6 is about 1:2. The conductive expansion layer 6 is electrically connected to the conductive layer 3. Figure 5 As shown, the conductive expansion layer 6 can expand after being heated or absorbing water in the body to form electrode contacts protruding outward from the contact window 5. Example
[0027] The present invention provides a graphene hydrogel neural microelectrode, which includes a long strip electrode body 1, the electrode body 1 includes an insulating base layer 2 (PI film, thickness 5μm), a conductive layer 3 (nano-gold layer, thickness 200nm) and an insulating cover layer 4 (PI film, thickness 5μm), the conductive layer 3 is wrapped and sealed by the insulating base layer and the insulating cover layer 4, such as Figure 6As shown, the insulating cover layer 4 is provided with a plurality of rectangular, long contact windows 5 at one end near the electrode body 1. A conductive expansion layer 6 (rectangular, approximately 20 μm thick) composed of graphene hydrogel is provided below and within the insulating cover layer 4 in the contact windows 5 and around the contact windows. The ratio of the total area of the contact windows 5 to the coverage area of the conductive expansion layer 6 is approximately 1:4. The conductive expansion layer 6 is electrically connected to the conductive layer 3. After being heated or absorbing water in the body, the conductive expansion layer 6 can expand to form electrode contacts protruding outward from the contact windows 5.
[0028] The graphene hydrogel neural microelectrodes corresponding to Examples 1 to 3 were prepared by the following method: S1. Use a vacuum thermal evaporation coating machine to deposit a 5 μm thick PI film or Parylene film on the substrate as an insulating base layer. S2. A gold or platinum metal layer is deposited on the insulating base layer to a thickness of 200 nm. A positive photoresist is coated on the metal layer. The photoresist is patterned using a planar photolithography technique to obtain a photoresist mask. The excess metal layer is then removed using a wet etching technique to obtain a conductive layer. S3. Print or apply a fully wetted graphene hydrogel on the area corresponding to the preset electrode contact at one end of the conductive layer, and after natural drying, obtain a conductive expansion layer with a thickness of about 20-25 μm; S4. Use the vacuum thermal evaporation coating machine again to deposit a layer of PI film or Parylene film covering the insulating base layer, the conductive layer, and the conductive expansion layer as an insulating covering layer with a thickness of 5 μm. Use reactive ion etching technology to open contact windows in the areas corresponding to the electrode contacts on the insulating covering layer to expose the central area of the conductive expansion layer.
[0029] The graphene hydrogel neural microelectrodes prepared in Examples 1 to 3 were used as detection objects. One end of the graphene hydrogel was immersed in physiological saline and fully soaked. After soaking, the graphene hydrogels swelled and all bulged outward from the corresponding contact windows. An electrical signal transmission test was then immediately performed: the graphene hydrogel bulging outward at the contact window at one end of the graphene hydrogel neural microelectrode was electrically stimulated, and the corresponding signal was clearly detected on the detector connected to the conductive layer at the other end of the graphene hydrogel neural microelectrode. At the same time, after comparison, it was found that the signal intensity detected when the electrode contact was the graphene hydrogel that had swelled after absorbing water was basically the same as when the electrode contact was a gold or platinum metal sheet. Since the bulging graphene hydrogel in the neural microelectrode provided by the present invention is more conducive to electrical stimulation, and the graphene hydrogel as an electrode contact also showed good adhesion and adsorption to neural tissue after testing, the graphene hydrogel neural microelectrode prepared by the present invention can effectively perform electrical stimulation and has excellent performance.
[0030] 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 principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A graphene hydrogel neural microelectrode, comprising an elongated electrode body, characterized in that: The electrode body includes an insulating base layer, a conductive layer and an insulating covering layer. The conductive layer is wrapped and sealed by the insulating base layer and the insulating covering layer. The insulating covering layer is provided with a contact window at one end close to the electrode body. A conductive expansion layer composed of graphene hydrogel is provided below the insulating covering layer in and around the contact window. The conductive expansion layer is electrically connected to the conductive layer. After being heated or absorbing water, the conductive expansion layer can expand to form an electrode contact protruding outward from the contact window. The graphene hydrogel is loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots and gold nanoparticles.
2. The graphene hydrogel neural microelectrode according to claim 1, characterized in that: The graphene hydrogel is prepared by the following method: Low-viscosity chitosan and acetic acid solution are fully stirred to obtain solution one, amino multi-walled carbon nanotubes and amino graphene quantum dot powders are added to solution one at room temperature, and the mixture is fully stirred to obtain solution two, tetrachloroauric acid is added to solution two under light-shielding conditions, and the mixture is fully stirred to obtain solution three, the temperature is raised to 35-40° C., glutaraldehyde is added to solution three, and the mixture is slowly stirred to perform cross-linking and reduction reactions, and after sufficient reaction, the mixture is filtered, washed with water, and naturally dried to a water content of less than 10%, thereby obtaining the graphene hydrogel loaded with amino multi-walled carbon nanotubes, amino graphene quantum dots, and gold nanoparticles.
3. The graphene hydrogel neural microelectrode according to claim 2, characterized in that: Solution 1 is prepared by mixing low-viscosity chitosan with a viscosity of 120-200 mPa.s and acetic acid solution with a volume concentration of 1.8-2.2% in a ratio of 8-12 mg:1 mL.
4. The graphene hydrogel neural microelectrode according to claim 3, characterized in that: The mass ratio of amino multi-walled carbon nanotubes and amino graphene quantum dot powder is 1.5-2.5:1, the dosage ratio of amino graphene quantum dot powder to solution one is 0.8-1 mg:2.5 mL, the mass ratio of tetrachloroauric acid to amino graphene quantum dot powder is 5-8:1, and the volume ratio of glutaraldehyde to solution three is 1:4-6.
5. The graphene hydrogel neural microelectrode according to claim 1, characterized in that: The ratio of the area of the contact window to the coverage area of the conductive expansion layer is 1:2-5.
6. The graphene hydrogel neural microelectrode according to claim 5, characterized in that: The number of the contact window is one or a plurality of contact windows arranged at intervals.
7. The graphene hydrogel neural microelectrode according to claim 6, characterized in that: The contact window is circular or rectangular.
8. A graphene hydrogel neural microelectrode according to any one of claims 1 to 7, characterized in that: The insulating base layer and the insulating cover layer are both PI films or Parylene films with a thickness of 1-15 μm.
9. A graphene hydrogel neural microelectrode according to any one of claims 1 to 7, characterized in that: The metal material of the conductive layer is gold or platinum, and the thickness is 0.1-1 μm.
10. A method for preparing the graphene hydrogel neural microelectrode according to any one of claims 1 to 9, characterized in that: The steps include: S1. Use a vacuum thermal evaporation coating machine to deposit a layer of PI film or Parylene film on the substrate as an insulating base layer; S2. Depositing a layer of gold or platinum on the insulating base layer to form a metal layer, coating the metal layer with a positive photoresist, patterning the photoresist using a planar photolithography technique to obtain a photoresist mask, and then using a wet etching technique to remove excess portions of the metal layer to obtain a conductive layer; S3. Printing or coating a fully wetted graphene hydrogel in the area corresponding to one end of the conductive layer and the preset electrode contact, and drying it naturally to obtain a conductive expansion layer; S4. Use the vacuum thermal evaporation coating machine again to deposit a layer of PI film or Parylene film covering the insulating base layer, the conductive layer, and the conductive expansion layer as an insulating covering layer. Use reactive ion etching technology to open contact windows in the areas corresponding to the electrode contacts on the insulating covering layer to expose the central area of the conductive expansion layer.
Citation Information
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