Low-impedance flexible dry electrode with micro-interlocking structure and preparation method

Abstract

The invention discloses a low-impedance flexible dry electrode with a micro-interlocking structure and a preparation method of the low-impedance flexible dry electrode. Comprising a micro-interlocking structure arranged on the surface of an electrode, the micro-interlocking structure comprises a first micro-interlocking structure and a second micro-interlocking structure, and the first micro-interlocking structure and / or the second micro-interlocking structure are / is selected to be arranged on the surface of the electrode according to the density of skin and hair; the first micro-interlocking structure comprises an array of double-barb anchor-shaped bulges, and each double-barb anchor-shaped bulge comprises a top upper barb and a middle lower barb; the second micro-interlocking structure comprises an array of wedge-shaped hook-shaped structures, and each wedge-shaped hook-shaped structure comprises a gradually-changing inclined face and a bottom arc-shaped groove. Different interlocking structures are selected according to the hair thickening degree, and the reliability of the flexible dry electrode is improved.

Description

Technical Field

[0001] This invention generally relates to the field of flexible electrode technology. More specifically, this invention relates to a low-impedance flexible dry electrode with a micro-interlocking structure and its fabrication method. Background Technology

[0002] In the prior art, research on flexible dry electrodes focuses on structural optimization and material improvement. For example, Chinese patent CN113208988A discloses a graphene-based flexible dry electrode with a uniformly distributed hemispherical protrusion structure on its surface, which reduces impedance by increasing the contact area, but does not consider the influence of hair on contact stability; US patent US20210068734A1 discloses a microneedle array dry electrode, which achieves low-impedance contact by piercing the stratum corneum of the skin with microneedles, but its rigid microneedles are prone to causing pain; Chinese patent CN114557126A discloses a fabric-based flexible electrode, which uses a fiber weaving structure to improve breathability, but the fibers are prone to sliding under dynamic friction, resulting in poor signal repeatability.

[0003] However, the above technologies have the following technical problems: (1) Insufficient contact stability: The mechanical interlocking ability between the planar or simple protruding structure (such as CN113208988A) and the skin folds and hair is weak. The contact impedance fluctuation exceeds 50% in motion, resulting in obvious motion artifacts; (2) Imbalance between safety and comfort: Although the microneedle structure (such as US20210068734A1) reduces the impedance, the microneedles (height 50-100μm) are easy to pierce the stratum corneum. The pain score of the subjects is 4.2 points (out of 10), and there is a risk of skin infection; (3) Poor synergy of material performance: The traditional PDMS substrate is highly hydrophobic (contact angle > 100°) and has poor compatibility with skin sweat; the pure nano silver conductive layer is easy to fall off. After peeling test, the retention rate of the conductive layer is less than 80%, which cannot meet the needs of long-term use. Summary of the Invention

[0004] To address at least the aforementioned issues in the background art regarding insufficient contact stability, imbalance between safety and comfort, and poor synergy of material properties in existing flexible dry electrodes, this invention proposes a low-impedance flexible dry electrode with a micro-interlocking structure and its preparation method. Different micro-interlocking structures are adapted to different hair density levels, and the PDM formulation ratio is adjusted to solve the aforementioned technical problems. Therefore, this invention provides solutions in the following aspects. A first aspect of the present invention provides a low-impedance flexible dry electrode with a micro-interlocking structure, comprising: a micro-interlocking structure disposed on the electrode surface, the micro-interlocking structure including a first micro-interlocking structure and a second micro-interlocking structure, wherein the first micro-interlocking structure and / or the second micro-interlocking structure are selectively arranged on the electrode surface according to the density of skin hair; the first micro-interlocking structure includes an array of double-barbed anchor-shaped protrusions, wherein each double-barbed anchor-shaped protrusion includes a top upper barb and a middle lower barb, the top upper barb forming a hook-lock with the skin epidermal folds to limit lateral sliding; the middle lower barb forming a hair-receiving groove with the base to avoid gaps caused by hair compression; the second micro-interlocking structure includes an array of wedge-shaped hook-shaped structures, wherein each wedge-shaped hook-shaped structure includes a gradient slope and a bottom arc-shaped groove, the gradient slope guiding the skin to adaptively conform and reduce local pressure; the bottom arc-shaped groove accommodating fine hairs to prevent hair from lifting the electrode.

[0005] In one embodiment, the method further includes: identifying body surface hair features, the hair features including the density of body surface hair; and dividing the body surface into hairy skin areas and hairless or sparsely haired skin areas based on the hair features.

[0006] In one embodiment, the step of selecting the arrangement of the first micro-interlocking structure and / or the second micro-interlocking structure on the electrode surface according to the density of skin hair includes: arranging a double barbed anchor-shaped protrusion array on the electrode surface in the hairy skin area, and arranging a wedge-shaped hook structure array on the electrode surface in the hairless or sparsely haired skin area.

[0007] In one embodiment, the step of selecting the arrangement of the first micro-interlocking structure and / or the second micro-interlocking structure on the electrode surface according to the density of skin hair includes: when the hair characteristics of the skin area are difficult to classify, arranging the interlocking structure array on the electrode surface in an alternating arrangement of the first micro-interlocking structure and the second micro-interlocking structure.

[0008] In one embodiment, the outer contour of the double barb anchor-shaped protrusion is J-shaped, the top upper barb is arranged at the end of the bent portion of the J-shaped structure, and the middle lower barb is arranged in the middle section of the straight portion of the J-shaped structure; the top upper barb and the middle lower barb have approximately the same height difference from the electrode surface and are arranged opposite to each other.

[0009] In one embodiment, the outer contour of the wedge-shaped hook structure is C-shaped, having an upper bend and a lower bend; the gradient slope begins at the contact surface between the C-shaped contour and the electrode surface and extends outward to the upper bend; the bottom arc-shaped groove includes the lower bend.

[0010] In one embodiment, the double-barbed anchor-shaped protrusion has an upper barb with a length of 2-3 μm at the top and a lower barb with a length of 1-2 μm in the middle, with the lower barb forming a hair-receiving groove with a depth of 3-4 μm with the base; the wedge-shaped hook-shaped protrusion has a gradually changing slope with an inclination angle of 30-45° on the side edge and an arc-shaped groove with a depth of 3-5 μm at the bottom.

[0011] In one embodiment, the height of the double barbed anchor-shaped protrusions is 8-15 μm, the spacing is 15-25 μm, and the inclination angle is 45-60°; the height of the wedge-shaped hook-shaped protrusions is 5-10 μm, and the spacing is 10-20 μm.

[0012] In one embodiment, the electrode further includes a modified PDMS flexible substrate and a nano-silver-graphene composite conductive layer; the components of the modified PDMS substrate are in the following mass ratio: PDMS prepolymer: curing agent: hydroxyl-terminated polyethylene glycol (PEG-400) = 8:1:0.2; the mass ratio of nano-silver particles to graphene nanosheets in the composite conductive layer is 95:5, and they are cross-linked by polydopamine.

[0013] A second aspect of the present invention provides a method for fabricating a low-impedance flexible dry electrode with a micro-interlocking structure, for fabricating the low-impedance flexible dry electrode described in any one of the preceding claims, comprising: S1. A silicon-based template with a micro-interlocked negative structure is prepared using photolithography, with a photoresist thickness of 20-30 μm; S2. Mix PDMS prepolymer, curing agent and PEG-400 in proportion, stir and degas, pour into the template, cure at 45°C for 2 hours, and peel off to obtain modified PDMS substrate with positive structure; S3. Add graphene nanosheets to 0.3 mol / L AgNO3 solution, disperse by ultrasonication at 300 W for 30 min, add dopamine hydrochloride solution to adjust pH to 8.5, and react at 40℃ for 3 h to obtain composite conductive liquid; S4. Immerse the PDMS substrate in the composite conductive liquid, remove it, and dry it at 60°C for 30 minutes to form a composite conductive layer, thus obtaining the finished electrode. A second aspect of the present invention provides a temperature measurement system for the internal flow channel of a heat exchanger, utilizing any of the above-mentioned methods for measuring the temperature of the internal flow channel of a heat exchanger, comprising: a co-doped silica fiber core located at the center of the sensing element; and a polyimide-alumina composite coating for the fiber cladding, which is annularly wrapped around the outside of the fiber core, with no gaps and without intruding into the fiber core area.

[0014] This invention achieves stable mechanical interlocking without puncture by using a subdivided microstructure design that is suitable for both hairy and hairless skin areas; it optimizes the composition of the substrate and conductive layer materials to balance flexibility, conductivity and adhesion, thereby improving long-term reliability; and through process improvements, it ensures the precision of microstructure molding and the uniformity of the conductive layer, reducing the cost of large-scale production. Attached Figure Description

[0015] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1 This illustrates the design flow of a low-impedance flexible dry electrode according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating a double-barbed anchor-shaped protrusion array according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating a wedge-shaped hook structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating two structural arrangements with spacing according to an embodiment of the present invention; Figure 5 This illustrates a method for preparing a low-impedance flexible dry electrode according to an embodiment of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the terms "first," "second," "third," and "fourth," etc., in the claims, specification, and drawings of this invention are used to distinguish different objects, rather than to describe a specific order. The terms "comprising" and "including" used in the specification and claims of this invention indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]." A first aspect of the present invention provides a low-impedance flexible dry electrode having a micro-interlocking structure.

[0017] In this invention, the flexible dry electrode consists of a three-layer structure: a subdivided micro-interlocking protrusion array layer, a modified PDMS flexible substrate, and a nano-silver-graphene composite conductive layer, with a total thickness of 50-80 μm, wherein the height of the micro-protrusion array is 5-15 μm, and the thickness of the conductive layer is 200-300 nm.

[0018] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 The diagram shown is a flowchart of the design process for the low-impedance flexible dry electrode of this invention.

[0019] From the appendix Figure 1 The low-impedance flexible dry electrode design process of the present invention includes steps 100-300, including: Step 100: A micro-interlocking structure is set on the electrode surface. The micro-interlocking structure includes a first micro-interlocking structure and a second micro-interlocking structure. The first micro-interlocking structure and / or the second micro-interlocking structure are arranged on the electrode surface according to the density of skin hair. Step 200, the first micro-interlocking structure includes an array of double-barbed anchor-shaped protrusions, wherein each double-barbed anchor-shaped protrusion includes a top upper barb and a middle lower barb. The top barb forms a hook-and-lock with the skin's epidermal folds to restrict lateral sliding; the middle lower barb forms a hair-receiving groove with the base to prevent hair from squeezing and creating gaps. Step 300, the second micro-interlocking structure includes an array of wedge-shaped hook structures, wherein each wedge-shaped hook structure includes a gradient slope and a bottom arc-shaped groove. The gradient slope is used to guide the skin to adapt and reduce local pressure; the bottom arc-shaped groove is used to accommodate fine hairs and prevent hairs from pushing up the electrodes.

[0020] This invention also includes identifying hair characteristics on the body surface, including the density of hair on the body surface; and dividing the body surface into hairy skin areas and hairless or sparsely haired skin areas based on the hair characteristics. Different micro-interlocking structures are matched according to different hair densities, thereby ensuring a stable adhesion between the dry electrode and the skin, thus reducing measurement errors caused by loosening of the fixation.

[0021] Specifically, the step of arranging the first micro-interlocking structure and / or the second micro-interlocking structure on the electrode surface according to the density of skin hair includes: arranging a double barbed anchor-shaped protrusion array on the electrode surface in the hairy skin area, and arranging a wedge-shaped hook structure array on the electrode surface in the hairless or sparsely haired skin area.

[0022] Appendix Figure 2 This is a schematic diagram of the double-barbed anchor-shaped protrusion array of the present invention. (See attached diagram.) Figure 2 As can be seen, the outer contour of the double barbed anchor protrusion in this invention is J-shaped, the top upper barb is arranged at the end of the bent part of the J-shaped structure; the middle lower barb is arranged in the middle section of the straight part of the J-shaped structure; the top upper barb and the middle lower barb have approximately the same height difference from the electrode surface and are arranged opposite to each other.

[0023] Furthermore, the double-barbed anchor-shaped protrusion array is used in hairy areas such as the forearm and scalp. The top of the double-barbed anchor-shaped protrusion has an upper barb with a length of 2-3 μm, and the middle has a lower barb with a length of 1-2 μm. The lower barb and the base form a hair-receiving groove with a depth of 3-4 μm.

[0024] Appendix Figure 3 This is a schematic diagram of the wedge-shaped hook structure array of the present invention. (See attached diagram.) Figure 3 As can be seen, the outer contour of the wedge-shaped hook structure in this invention is C-shaped, with an upper bent portion and a lower bent portion; the gradient slope starts at the contact surface between the C-shaped contour and the electrode surface, and extends outward to the upper bent portion; the bottom arc-shaped groove includes the lower bent portion.

[0025] Furthermore, the wedge-shaped hook-shaped protrusion array is used, for example, in hairless / micro-haired areas of the chest, wherein the side edges of the wedge-shaped hook-shaped protrusions are gradually sloped at an angle of 30-45°, and the bottom is provided with an arc-shaped groove with a depth of 3-5μm.

[0026] The parameters and functional characteristics of the two structures mentioned above are shown in Table 1.

[0027] Table 1. Structural parameters and functional characteristics of the two types of protrusion arrays In a preferred embodiment of the invention, the double-barbed anchor structure and the wedge-shaped hook structure can be used interchangeably to enhance the adaptability of the micro-interlocking structure, thereby enabling its application to a wider range of skin conditions. (Appendix) Figure 4 This is a schematic diagram of the double-barbed anchor-shaped protrusions and wedge-shaped hook-shaped structure array of the present invention. (See attached diagram.) Figure 4 It is known that the double-barbed anchor structure and the wedge-shaped hook structure are arranged at a 1:1 interval. Optionally, the interval ratio of the double-barbed anchor structure and the wedge-shaped hook structure can be selected to other suitable ratios, such as 2:1, 2:3, etc. The above-mentioned staggered micro-interlocking structure can be used for body parts with both long and short hair, such as buzz cuts, where the distribution of hair is complex and difficult to classify into different areas.

[0028] A second aspect of the present invention discloses a method for fabricating a low-impedance flexible dry electrode with a micro-interlocking structure. For example... Figure 5 The diagram illustrates the method for preparing the flexible dry electrode according to the present invention. (The diagram is derived from...) Figure 5 It can be seen that the flexible dry electrode fabrication method includes steps S1-S4: S1. A silicon-based template with a micro-interlocked negative structure is prepared using photolithography, with a photoresist thickness of 20-30 μm; S2. Mix PDMS prepolymer, curing agent and PEG-400 in proportion, stir and degas, pour into the template, cure at 45°C for 2 hours, and peel off to obtain modified PDMS substrate with positive structure; S3. Add graphene nanosheets to 0.3 mol / L AgNO3 solution, disperse by ultrasonication at 300 W for 30 min, add dopamine hydrochloride solution to adjust pH to 8.5, and react at 40℃ for 3 h to obtain composite conductive liquid; S4. Immerse the PDMS substrate in the composite conductive liquid, remove it and dry it at 60°C for 30 minutes to form a composite conductive layer and obtain the finished electrode.

[0029] Furthermore, the key process steps for modifying PDMS flexible substrates include: Component ratio (mass ratio): PDMS prepolymer (SYLGARD184): curing agent: hydroxyl-terminated polyethylene glycol (PEG-400) = 8:1:0.2; Preparation process: Mix the three ingredients and stir for 30 minutes (500 rpm), then degas under vacuum for 20 minutes (vacuum degree -0.09 MPa), and heat at 45℃ for 2 hours to cure. Performance specifications: Contact angle 72° (original PDMS is 105°), elongation at break 250% (original is 180%), Shore A hardness 30±2°.

[0030] Furthermore, the key process steps for the nano-silver-graphene composite conductive layer include: Component ratio (mass ratio): silver nanoparticles (diameter 50-100nm): graphene nanosheets (thickness 1-3nm, sheet diameter 1-5μm) = 95:5, polydopamine (PDA) accounts for 3% of the total mass; Preparation process: ① Add graphene nanosheets to a 0.3 mol / L AgNO3 solution and ultrasonically disperse for 30 min (power 300 W, frequency 40 kHz). ② Add 1 mg / mL dopamine hydrochloride solution, adjust the pH to 8.5, and react at a constant temperature of 40℃ for 3 hours; ③ Immerse the modified PDMS substrate in the above solution, remove it and dry it at 60°C for 30 minutes to form a composite conductive layer; Performance specifications: Shear resistance 3.5Ω / sq (original pure nano silver layer is 8Ω / sq), conductive layer retention rate after peel test is 92% (original is 75%).

[0031] Furthermore, the complete fabrication process of the finished electrode includes: (1) Mold preparation: Micro-interlocking negative templates are prepared on silicon wafers using photolithography. The photoresist thickness is 20-30 μm, the exposure time is 30 s, and the mold is baked for 1 h (120℃) after development. (2) Substrate molding: The modified PDMS mixture is poured onto the negative template and cured at 45°C for 2 hours. The substrate with positive structure is then peeled off. (3) Conductive layer deposition: The conductive layer is deposited on the surface of the substrate microstructure according to the above composite conductive layer process to finally obtain the finished electrode.

[0032] This invention uses "contact impedance (1kHz), motion artifact amplitude (ECG), signal-to-noise ratio (EEG), and comfort score" as core indicators, and conducts comparative experiments with existing technologies. The results are shown in Table 2 below (n=3, data are mean ± standard deviation): Table 2 Comparison of Experimental Results Note: The motion artifact test conditions were "arm swing 30 times / minute for 30 minutes"; the comfort score was the result of a blind test of 20 healthy subjects (18-45 years old); the long-term stability test was conducted by wearing the device for 8 hours a day for 7 consecutive days and monitoring impedance changes.

[0033] It can be seen that the present invention has the following significant effects: (1) Significantly improved dynamic contact stability: When the double barbed anchor structure moves in the hairy area, the contact impedance fluctuation is ≤8% (planar electrode >50%), and the motion artifact amplitude is only 8.2μV, which is 83% lower than that of the planar electrode; (2) Enhanced adaptability to multiple scenarios: The two subdivided structures cover the hairy / hairless areas respectively, solving the problem of "poor adaptability of single structure" of existing electrodes. The EEG signal-to-noise ratio in the hairy area reaches 26.5dB, which is 11.3% higher than that of the microneedle electrode; (3) Synergistic optimization of material properties: The modified The hydrophilicity of the PDMS substrate is improved by 31%, the sheet resistance of the composite conductive layer is reduced by 56%, and the adhesion is improved by 23%, meeting the requirements for long-term wear for 7 days; (4) Safety and comfort are balanced: there is no risk of puncture, the comfort score is ≥9.2 points (microneedle electrode is only 5.3 points), while maintaining the advantage of low impedance (28.6kΩ in the hairy area, close to the level of microneedle electrode); (5) High feasibility of large-scale production: the process of photolithography + casting + chemical reduction is adopted, the mold reuse rate is >50 times, the single batch production efficiency is 40% higher than that of microneedle electrode, and the cost is reduced by 35%.

[0034] While various embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and intent of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover modular compositions, equivalents, or alternatives within the scope of these claims.

Claims

1. A low-impedance flexible dry electrode with a micro-interlocking structure, characterized in that, include: A micro-interlocking structure is disposed on the electrode surface, the micro-interlocking structure including a first micro-interlocking structure and a second micro-interlocking structure, the first micro-interlocking structure and / or the second micro-interlocking structure are arranged on the electrode surface according to the density of skin hair. The first micro-interlocking structure includes an array of double-barbed anchor-shaped protrusions, wherein each double-barbed anchor-shaped protrusion includes a top upper barb and a middle lower barb. The top barb forms a hook-and-lock with the skin's epidermal folds to restrict lateral sliding; the middle lower barb forms a hair-receiving groove with the base to prevent hair from squeezing and creating gaps. The second micro-interlocking structure includes an array of wedge-shaped hook structures, wherein each wedge-shaped hook structure includes a gradient slope and a bottom arc-shaped groove. The gradient slope is used to guide the skin to adapt and reduce local pressure; the bottom arc groove is used to accommodate fine hairs and prevent hairs from pushing up the electrodes.

2. The low-impedance flexible dry electrode according to claim 1, characterized in that, Also includes: Identify body hair characteristics, including the density of body hair; Based on the hair characteristics, the body surface is divided into hairy skin areas and hairless or sparsely haired skin areas.

3. The low-impedance flexible dry electrode according to claim 2, characterized in that, The step of arranging the first micro-interlocking structure and / or the second micro-interlocking structure on the electrode surface according to the density of skin hair includes: arranging a double barbed anchor-shaped protrusion array on the electrode surface in the hairy skin area, and arranging a wedge-shaped hook structure array on the electrode surface in the hairless or sparsely haired skin area.

4. The low-impedance flexible dry electrode according to claim 2, characterized in that, The step of selectively arranging the first micro-interlocking structure and / or the second micro-interlocking structure on the electrode surface according to the density of skin and hair includes: When the hair features of the skin area are difficult to classify, the electrode surface interlocking structure array is arranged in an alternating pattern of the first micro-interlocking structure and the second micro-interlocking structure.

5. The low-impedance flexible dry electrode according to claim 1, characterized in that, The outer contour of the double barbed anchor protrusion is J-shaped. The top upper barb is arranged at the end of the bent part of the J-shaped structure; the middle lower barb is arranged in the middle section of the straight part of the J-shaped structure; the top upper barb and the middle lower barb have approximately the same height difference from the electrode surface and are arranged opposite to each other.

6. The low-impedance flexible dry electrode according to claim 1, characterized in that, The outer contour of the wedge-shaped hook structure is C-shaped, with an upper bend and a lower bend; the gradient slope starts at the contact surface between the C-shaped contour and the electrode surface and extends outward to the upper bend; the bottom arc-shaped groove includes the lower bend.

7. The low-impedance flexible dry electrode according to any one of claims 1-6, characterized in that, The double-barbed anchor-shaped protrusion has an upper barb with a length of 2-3 μm at the top and a lower barb with a length of 1-2 μm in the middle. The lower barb forms a hair-accommodating groove with a depth of 3-4 μm with the base. The wedge-shaped hook-shaped protrusion has a gradually changing slope with an inclination angle of 30-45° on the side edge and an arc-shaped groove with a depth of 3-5 μm at the bottom.

8. The low-impedance flexible dry electrode according to claim 7, characterized in that, The height of the double barbed anchor-shaped protrusions is 8-15μm, the spacing is 15-25μm, and the inclination angle is 45-60°; the height of the wedge-shaped hook-shaped protrusions is 5-10μm, and the spacing is 10-20μm.

9. The low-impedance flexible dry electrode according to claim 8, characterized in that: The electrode also includes a modified PDMS flexible substrate and a nano-silver-graphene composite conductive layer; The components of the modified PDMS substrate are in the following mass ratio: PDMS prepolymer: curing agent: hydroxyl-terminated polyethylene glycol (PEG-400) = 8:1:0.2; The composite conductive layer has a mass ratio of silver nanoparticles to graphene nanosheets of 95:5 and is cross-linked with polydopamine.

10. A method for fabricating a low-impedance flexible dry electrode with a micro-interlocking structure, used to fabricate the low-impedance flexible dry electrode as described in any one of claims 1-9, characterized in that, include: S1. A silicon-based template with a micro-interlocked negative structure is prepared using photolithography, with a photoresist thickness of 20-30 μm; S2. Mix PDMS prepolymer, curing agent and PEG-400 in proportion, stir and degas, pour into the template, cure at 45°C for 2 hours, and peel off to obtain modified PDMS substrate with positive structure; S3. Add graphene nanosheets to 0.3 mol / L AgNO3 solution, disperse by ultrasonication at 300 W for 30 min, add dopamine hydrochloride solution to adjust pH to 8.5, and react at 40℃ for 3 h to obtain composite conductive liquid; S4. Immerse the PDMS substrate in the composite conductive liquid, remove it and dry it at 60°C for 30 minutes to form a composite conductive layer and obtain the finished electrode.

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