A sea star-mimicking tube foot array hydrogel electrode and a preparation method thereof

Abstract

The application discloses a starfish-imitated tube foot array hydrogel electrode and a preparation method thereof. The bottom of the conductive hydrogel electrode is provided with a starfish-imitated tube foot array. A single starfish-imitated tube foot comprises a stem and a terminal biomimetic sucker. The outer side of the sucker is a circular table structure, and the inner side is a cavity composed of a hemisphere. The integrated tube foot microstructure of the electrode is obtained by laser cutting of the hydrogel. First, the inner cavity structure is cut. Then, the outer side of the biomimetic tube foot shape is cut. Finally, the single biomimetic tube foot is inserted into the block-shaped hydrogel to form an array. The preparation method of the conductive hydrogel electrode comprises the following steps: first, a prepolymer is synthesized; then, the prepolymer, cationic monomers and anionic monomers are polymerized to obtain a hydrogel with anti-swelling and stable and excellent conductive performance. The conductive hydrogel electrode has the self-adhesion and anti-swelling ability when working underwater, can be closely combined with human skin, reduces the electrode-skin impedance, and improves the quality of underwater electromyographic signal collection.

Description

Technical Field

[0001] This invention belongs to the field of biomedical electrotechnology, specifically relating to a starfish-inspired tube foot array hydrogel electrode and its preparation method. Background Technology

[0002] Epidermal electromyography (EMG) signals have been widely used in various fields such as motion monitoring, health management, and human-computer interaction, providing a convenient and non-invasive method for disease diagnosis and health assessment. In recent years, with the research and advancement of skin electronics technology, epidermal EMG electrodes have seen innovations in materials, structure, and processes, but these have mainly focused on applications in dry environments. Developing high-quality underwater EMG signal acquisition technology is of great significance for better assessing the activity status of swimmers and divers, and for providing early warnings of underwater safety. Existing epidermal EMG electrodes have poor water resistance and wet adhesion, and often exhibit high interfacial impedance, making it difficult to achieve continuous, long-term, high signal-to-noise ratio bioelectrical signal monitoring in water.

[0003] Hydrogels, with their unique advantages such as high water content, high modulus matching with skin tissue, and biocompatibility, have become one of the important candidate materials for next-generation epidermal electrodes with excellent comprehensive performance. However, the underwater application of traditional hydrogel electrodes is limited, mainly for the following three reasons: First, due to the large number of hydrophilic groups, traditional hydrogels exhibit significant swelling in water, leading to a decrease in the mechanical and electrical properties of the electrode; second, the diffusion of small molecules in conductive hydrogels also reduces their stability in water; and finally, the hydration layer formed on the surface of conductive hydrogels reduces their wet adhesion. Overcoming these three challenges is crucial for developing stable hydrogel electrodes for underwater electromyography (EMG) acquisition.

[0004] A search of existing technologies revealed that Jungmok Seo et al. from Yonsei University in South Korea published an article in Advanced Science, 2023, 10, 2207237, entitled "Intrinsically Nonswellable Multifunctional Hydrogel with Dynamic Nanoconfinement Networks for Robust Tissue-Adaptable Bioelectronics," reporting a multifunctional hydrogel. This hydrogel's swelling phenomenon is limited by the weak interactions between a hydrophilic polymer matrix and tannic acid and functionalized carbon nanotubes. Simultaneously, N-hydroxysuccinimide-functionalized polyacrylic acid enables the hydrogel to adhere to the skin tissue surface and maintain stable contact. However, its long-term underwater performance and adhesion to dynamic tissues are unknown, leading to uncertainty regarding failure in practical applications.

[0005] Patent JP2020092967A discloses an underwater bioelectrode that can monitor signals from moving objects underwater and suppress electromagnetic noise. An Ag / AgCl disc electrode is located inside an electromagnetic shielding material. After the shielding material is pressed against the skin, a liquid-tight chamber is formed above the measurement point, allowing for non-contact acquisition of electromyography (EMG) and electrocardiogram (ECG) signals in water containing electrolytes. While the electrode can easily and stably acquire bioelectrical signals underwater, it is prone to failure in water environments with high conductivity (greater than 10.0 S / m). Continuous pressure is required to maintain electrode contact with the skin surface, limiting its applicability. Furthermore, the impact of desorption on the skin is not considered.

[0006] US Patent 20230108715 discloses a waterproof electrophysiological data recording system for non-invasive recording of marine mammals' sleep in the wild. It embeds gold cup electrodes between two layers of neoprene rubber and uses multi-layered waterproof materials to treat the electrode wire solder joints, enabling underwater recording of animal electroencephalograms, electrocardiograms, electromyograms, and electrooculograms. However, in practical use, this system requires the application of neoprene rubber adhesive to the animal's skin, and the electrodes lack self-adhesive properties, making it inconvenient to use.

[0007] Patent CN116602686A discloses a biomimetic hydrophobic wet-adhesion flexible electrode for urodynamic monitoring and its preparation method, which has a biomimetic superhydrophobic outer layer, a stretchable conductive layer, and a hydrogel adhesive layer. The biomimetic superhydrophobic outer layer contains lotus leaf microstructures and hydrophobic groups, which can prevent problems such as water absorption and swelling of the hydrogel and interface desorption caused by water stains and urine. However, the gel itself does not have anti-swelling ability, and there are unstable interfaces between the layers. Interlayer slippage under deformation may cause water leakage, resulting in the hydrogel absorbing a large amount of water, reducing its adhesion to the skin, and compromising the long-term durability of the electrode.

[0008] Patent CN116376104A discloses a method for processing hydrogel-based Janus porous films based on femtosecond lasers. It uses femtosecond laser in-situ etching technology to form conical through holes in one step. The size of the conical holes is controlled by adjusting parameters such as laser scanning speed, scanning spacing and scanning number. However, the through hole structure is relatively simple and the processing difficulty is low.

[0009] In summary, current integrated underwater electrode technology is relatively limited. To acquire more stable electromyographic signals underwater, there is an urgent need to develop novel epidermal electrodes with waterproof, self-adhesive, and low-impedance properties. Firstly, by designing a conductive hydrogel molecular structure, the electrode's chemical wet adsorption capacity and underwater anti-swelling ability can be improved, reducing skin contact impedance. Secondly, a biomimetic suction cup structure on the gel surface can be constructed using laser processing to further enhance the electrode's underwater electromyographic signal acquisition capability. Summary of the Invention

[0010] To overcome the shortcomings of existing technologies, this invention provides a starfish-inspired tube foot array hydrogel electrode and its preparation method. The conductive hydrogel electrode has a starfish-inspired tube foot array at its bottom. Each starfish-inspired tube foot includes a stem and a biomimetic suction cup at its end. The suction cup has a frustum structure on the outside and a cavity composed of hemispheres on the inside. The integrated tube foot microstructure of this electrode is obtained by laser cutting of the hydrogel. First, the inner cavity structure is cut out; second, the shape of the outer biomimetic tube foot is cut; finally, individual biomimetic tube feet are inserted into the block hydrogel to form an array. The conductive hydrogel used in the electrode is prepared by first synthesizing a prepolymer, then polymerizing the prepolymer, cationic monomers, and anionic monomers to obtain a hydrogel that is resistant to swelling and has stable and excellent conductivity. This conductive hydrogel electrode has self-adhesive wet adhesion and anti-swelling ability when working underwater, allowing it to adhere closely to human skin, reducing electrode-skin impedance, and improving the quality of underwater electromyography signal acquisition.

[0011] The technical solution adopted by this invention to solve its technical problem includes the following steps:

[0012] A starfish-inspired tube foot array hydrogel electrode comprises a block hydrogel and a starfish-inspired tube foot array;

[0013] The blocky hydrogel and the starfish-like tube foot array are made of the same hydrogel.

[0014] The starfish-like tube foot array includes multiple tube feet, each tube foot including a stem and a suction cup. The stem is a solid cylinder and the suction cup has a cup-shaped structure; one end of the stem is the suction cup.

[0015] The bottom surface of the blocky hydrogel is arranged with a circular blind hole array. The number of circular blind holes is the same as the number of starfish tube feet, and the radius of the circular blind holes is the same as the radius of the starfish tube foot stem.

[0016] The other end of the stem of each tube foot is inserted into a circular blind hole and bonded to the block hydrogel through the adhesiveness of the hydrogel itself, forming a starfish-like tube foot array.

[0017] Furthermore, the inner side of the suction cup contains an outwardly protruding hemisphere, and the remaining area is the suction cup cavity.

[0018] Furthermore, the top ring of the suction cup has a micro-pleated structure.

[0019] A method for preparing a starfish-inspired tube foot array hydrogel electrode includes the following steps:

[0020] Step 1: Prepare the prepolymer;

[0021] Step 2: Add cationic monomers, anionic monomers, and potassium persulfate to the prepolymer and heat at 80°C for 3-4 hours;

[0022] Step 3: Laser cutting of the gel yields the tube feet, including the stem and suckers;

[0023] Step 4: Laser cut the bottom of the blocky gel to obtain a circular blind hole array;

[0024] Step 5: Insert the stems of all the tube feet into the circular blind holes and bond them to the block hydrogel through the adhesiveness of the hydrogel itself to form a starfish-like tube foot array.

[0025] Further, step 1 specifically includes:

[0026] Step 1-1: Dissolve N,N′-methylenebisacrylamide, sodium dodecyl sulfate, and potassium persulfate in deionized water to prepare three raw material solutions;

[0027] Step 1-2: Mix the three raw material solutions prepared in Step 1-1 with cationic monomers or anionic monomers and polyethylene glycol methyl ether acrylate, and react at 70 degrees for 30 minutes at a speed of 300 rpm to obtain the prepolymer;

[0028] Further, in steps 1-2, the mass ratio of cationic monomer, polyethylene glycol methyl ether acrylate, N,N′-methylenebisacrylamide dodecyl sulfate, potassium persulfate, and sodium dodecyl sulfate is 1430:1200:77:25:270, with the mass unit being mg.

[0029] Furthermore, in step 2, the volume ratio of cationic monomer, anionic monomer, prepolymer, and potassium persulfate is 227:104:500:60, with the volume unit being μL.

[0030] Furthermore, the blocky hydrogel is 4-9 mm long, 3-9 mm wide, 3 mm high, and has a blind hole depth of 1 mm.

[0031] Furthermore, the outer side of the suction cup is a frustum structure, and the inner side is a hollow hemisphere. The outer diameter of the suction cup is 0.7-1 mm, the inner diameter is 0.5-0.8 mm, and the height is 0.5-0.8 mm; the stem diameter is 0.2-0.5 mm, and the height is 1-1.5 mm.

[0032] Furthermore, the outer side of the suction cup is a frustum structure, and the inner side is a hollow hemisphere. The outer diameter of the suction cup is 0.7 mm, the inner diameter is 0.5 mm, and the height is 0.5 mm; the stem diameter is 0.2 mm and the height is 1.5 mm.

[0033] The beneficial effects of this invention are as follows:

[0034] 1. This invention, through the design of hydrogel molecular components, enables the electrode to have excellent anti-swelling ability, and can stably maintain conductivity and adhesion underwater without any encapsulation. This integrated electrode can ensure high-quality underwater electromyography signal acquisition.

[0035] 2. This invention adopts a biomimetic approach and designs a starfish-like tube foot array based on laser processing. On the basis of the adhesiveness of the hydrogel material itself, the tube foot suction cup structure further enhances the wet adsorption capacity of the electrode, while increasing the contact area between the skin and the electrode, reducing the electrode-skin interface impedance, and improving the stability of the electrode. Attached Figure Description

[0036] Figure 1 (a) is a schematic diagram of the conductive hydrogel electrode of the starfish-like tube foot array of the present invention; (b) is a photograph of the starfish tube foot adhering to a wet surface; (c) is a schematic diagram of the conductive hydrogel electrode structure of the starfish-like tube foot array of the present invention.

[0037] Figure 2 This is a schematic diagram of the preparation process of the conductive hydrogel of the present invention.

[0038] Figure 3 This is a schematic diagram of the conductive hydrogel electrode integration steps of the starfish-like tube foot array of the present invention.

[0039] Figure 4 The diagram shows the underwater working principle of the suction cup structure of the single starfish-like tube foot of the present invention; (a) is the structure when the starfish-like tube foot is not attached to the human body, (b) is the structure after the suction cup is attached to the skin and the air is expelled; (c) is the principle of the starfish-like tube foot adhering to the skin when subjected to normal tension underwater, and (d) is the principle of the starfish-like tube foot adhering to the skin when subjected to shear force underwater.

[0040] Figure 5 This is a schematic diagram of the laser processing steps for the starfish-like tube foot suction cup array in Embodiment 2 of the present invention.

[0041] Figure 6 This is a schematic diagram of the laser processing steps for the starfish-like tube foot suction cup array in Embodiment 3 of the present invention.

[0042] Figure 7 This is a schematic diagram of the laser processing steps for the starfish-like tube foot suction cup array in Embodiment 4 of the present invention.

[0043] In the figure, 1- starfish-like tube foot; 2- blocky hydrogel. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] This invention provides a starfish-inspired tube foot array hydrogel electrode and its preparation method. The electrode comprises a block-shaped hydrogel portion and a biomimetic tube foot array. The hydrogel has abundant hydrophilic groups, enabling it to generate electrostatic interactions and form a tight adhesion with the skin. The conductive hydrogel electrode exhibits excellent anti-swelling properties and can stably maintain high conductivity underwater. Based on the principle of vacuum adsorption, the starfish-inspired tube foot array is pressed tightly against the skin, ensuring stable adhesion of the conductive hydrogel electrode to the skin during underwater use. Simultaneously, the tight adhesion between the starfish-inspired tube foot array and the skin reduces the electrode-skin interface impedance, forming a sealed cavity at the electromyography (EMG) acquisition site, preventing water from affecting weak EMG signals and effectively improving signal acquisition quality.

[0046] The technical solution adopted by this invention to solve its technical problem is as follows:

[0047] A conductive hydrogel electrode based on a laser-processed starfish-like tube foot array, comprising a bulk hydrogel and a starfish-like tube foot array;

[0048] The blocky hydrogel and the starfish-like tube foot array are the same type of hydrogel, and the starfish-like tube foot array is fabricated by nanosecond or picosecond laser processing.

[0049] Each of the starfish-like tube foot arrays includes a stem and a suction cup. The stem is a solid cylinder and the suction cup is a cup-shaped structure.

[0050] The bottom surface of the blocky hydrogel is arranged with a circular blind hole array. The number of circular blind holes is the same as the number of starfish tube feet, and the radius is the same as the radius of the starfish tube foot stem.

[0051] A starfish-inspired tube foot array hydrogel electrode and its preparation method include the following steps:

[0052] Step 1: Prepare the prepolymer;

[0053] Step 2: Add cationic monomer, anionic monomer, and potassium persulfate to the prepolymer prepared in Step 1, and heat at 80°C for 3-4 hours;

[0054] Step 3: Laser cutting of the gel yields a tube-foot sucker-like structure, consisting of a stem and suckers;

[0055] Step 4: Laser cut the bottom of the blocky gel to obtain a circular blind hole array;

[0056] Step 5: Insert all the tube foot suction cups into the circular blind holes. The tube foot stems and the block hydrogel are bonded together by the adhesive properties of the hydrogel itself to form a starfish-like tube foot array.

[0057] Step 1 is as follows:

[0058] 1.1) Dissolve N,N′-methylenebisacrylamide, sodium dodecyl sulfate, and potassium persulfate in deionized water to prepare three raw material solutions;

[0059] 1.2) Mix the three raw material solutions prepared in step 1) with cationic monomer (or anionic monomer) and polyethylene glycol methyl ether acrylate, and react at 70 degrees for 30 minutes at a speed of 300 rpm to obtain the prepolymer;

[0060] In step 1.2, the mass ratio of cationic monomer, polyethylene glycol methyl ether acrylate, N,N′-methylenebisacrylamide dodecyl sulfate, potassium persulfate, and sodium dodecyl sulfate is 1430:1200:77:25:270, and the mass unit is mg.

[0061] In step 2, the volume ratio of cationic monomer, anionic monomer, prepolymer, and potassium persulfate is 227:104:500:60, with the volume unit being μL.

[0062] The blocky hydrogel is 4-9 mm long, 3-9 mm wide, and 3 mm high. The diameter of the blind holes is set according to the stem diameter, and the depth of the blind holes is 1 mm.

[0063] The starfish-like tube foot consists of a stem and a sucker. The sucker has a frustum structure on the outside and a hollow hemisphere on the inside. The outer diameter is 0.7–1 mm, the inner diameter is 0.5–0.8 mm, and the height is 0.5–0.8 mm. The stem has a diameter of 0.2–0.5 mm and a height of 1–1.5 mm.

[0064] Example:

[0065] In the following embodiments of the present invention, the chemical reagents involved include:

[0066] Cationic monomers, anionic monomers, polyethylene glycol methyl ether acrylate (PEGA), N,N′-methylenebisacrylamide dodecyl sulfate (MBA), potassium persulfate (KPS), sodium dodecyl sulfate (SDS).

[0067] Preparation method steps:

[0068] Step 1: Dissolve N,N′-methylenebisacrylamide, sodium dodecyl sulfate, and potassium persulfate in deionized water to prepare three raw material solutions;

[0069] Step 2: Add the three raw material solutions prepared in Step 1, the cationic monomer, and polyethylene glycol methyl ether acrylate to the sampling tube, gently shake to mix, and react the mixture at 70°C for 30 minutes at a speed of 300 rpm to obtain the prepolymer;

[0070] Step 3: Add cationic monomer, anionic monomer, and potassium persulfate to the cationic prepolymer prepared in Step 2, and heat at 80°C for 3-4 hours to obtain hydrogel.

[0071] Step 4: Laser cutting of conductive hydrogel. First, the upper surface of the columnar hydrogel is cut with a laser at a fixed depth to obtain a hemispherical depression, which serves as a suction cup for the tube feet. Then, the lower surface of the columnar hydrogel is cut with a laser at a fixed depth to remove the excess material around it, resulting in a suction cup-like structure consisting of a stem and a suction cup.

[0072] Step 5: Laser depth cutting of the bottom of the block hydrogel to obtain a circular blind hole array, the diameter of the blind holes being similar to the diameter of the tube foot stem;

[0073] Step 6: Insert all the tube foot suction cup arrays into the circular blind holes. The tube foot stems and the blocky hydrogel are bonded together by their own adhesiveness to form a starfish-like tube foot array.

[0074] In step 2, the mass ratio of cationic monomer, polyethylene glycol methyl ether acrylate, N,N′-methylenebisacrylamide dodecyl sulfate, potassium persulfate, and sodium dodecyl sulfate is 1430:1200:77:25:270, with the mass unit being mg.

[0075] In step 3, the volume ratio of cationic monomer, anionic monomer, prepolymer, and potassium persulfate is 227:104:500:60, with the volume unit being μL.

[0076] The block-shaped gel is 4mm long, 3mm wide, and 3mm high. The diameter of the blind holes is set according to the stem diameter, and the depth is 1mm.

[0077] The starfish-like tube foot consists of a stem and a sucker. The sucker has a frustum structure on the outside and a hollow hemisphere on the inside. The outer diameter is 0.7-1 mm, preferably 0.7 mm, the inner diameter is 0.5-0.8 mm, preferably 0.5 mm, and the height is 0.5-0.8 mm, preferably 0.5 mm. The stem diameter is 0.2-0.5 mm, preferably 0.2 mm, and the height is 1.5 mm.

[0078] The number of starfish-like tube feet is set according to the size of the tube feet.

[0079] Example 1:

[0080] See Figure 1 This is a schematic diagram of a conductive hydrogel electrode with a starfish-like tube foot array provided in Embodiment 1 of the present invention. In Embodiment 1 of the present invention, the conductive hydrogel electrode includes: a block hydrogel 1 and a starfish-like tube foot array 2.

[0081] Reference Figure 2 As shown, the preparation and synthesis of conductive hydrogels in this embodiment of the invention includes the following steps:

[0082] Step 1: Dissolve N,N′-methylenebisacrylamide, sodium dodecyl sulfate, and potassium persulfate in deionized water to prepare three raw material solutions;

[0083] Step 2: Mix the three raw material solutions prepared in Step 1 with the cationic monomer and polyethylene glycol methyl ether acrylate, and react at 70°C for 30 minutes;

[0084] Step 3: Add cationic monomer, anionic monomer, and potassium persulfate to the cationic prepolymer prepared in Step 1, and heat at 80°C for 3 hours.

[0085] Reference Figure 3 As shown, the laser cutting of the starfish-like tube foot array in this embodiment of the invention includes the following steps:

[0086] Step 1: Laser depth cutting of columnar hydrogel to obtain solid cylinder, hemispherical suction cup cavity, and tube foot structure, forming an independent starfish-like tube foot gel; wherein the suction cup has an outer diameter of 0.7mm, an inner diameter of 0.5mm, and a height of 0.5mm, and the stem has a diameter of 0.2mm and a height of 1.5mm.

[0087] Step 2: Laser-cut the bottom of the block hydrogel to obtain a 3×2 circular blind hole array. The diameter of the blind holes is the same as the stem diameter, and the depth is 1mm.

[0088] Step 3: Insert all the tube foot suction cup arrays into the circular blind holes. The tube foot stems and the block hydrogel are bonded together by their own adhesiveness to form a starfish-like tube foot array.

[0089] Reference Figure 4 As shown, the underwater working principle of the suction cup structure mimicking the tube foot of a starfish in this embodiment of the invention is as follows:

[0090] When the gel electrode is pressed against the skin, the suction cup expels air, creating suction due to the vacuum effect, causing the suction cup to adhere tightly to the skin. When the electrode is submerged underwater, some water inevitably seeps into the suction cup structure, forming a water layer between the suction cup and the skin. Due to capillary action, an additional adhesive force exists between the suction cup and the skin, ensuring a tight fit even when normal tension is applied. When the electrode is worn and moved underwater, i.e., when shear force is applied, friction also exists between the suction cup and the skin, making the electrode less likely to fall off.

[0091] Example 2: Except for the starfish-like tube foot structure and its laser cutting steps, it is the same as Example 1.

[0092] Reference Figure 5 As shown, in this embodiment, the inner side of the suction cup contains an outwardly protruding hemisphere, and the remaining area is the suction cup cavity.

[0093] The laser cutting of a starfish-like tube foot array, as exemplified by this invention, includes the following steps:

[0094] Step 1: Cut the block hydrogel into a solid cylindrical array. The cylinders are 1mm in diameter and 1mm in height. The number of cylinders and the spacing between them are set according to the cylinder diameter.

[0095] Step 2: Cut out a cavity and an outward convex hemispherical structure inside the cylinder. The outer diameter of the top ring is 1mm, the inner diameter is 0.8mm, the cavity depth is 0.4mm, and the diameter of the hemisphere is 0.6mm.

[0096] Step 3: Arrange circular blind holes at the bottom of another block of hydrogel. The diameter of the blind holes is the same as the diameter of the stem and the depth is 1 mm, forming a 3×2 array.

[0097] Step 4: Insert all the tube foot suction cup arrays into the circular blind holes. The tube foot stems and the block hydrogel are bonded together by the adhesive properties of the hydrogel to form a starfish-like tube foot array.

[0098] Compared with the method of Example 1, Example 2 changes the bionic suction cup structure. The advantage is that the microstructure containing the convex hemisphere inside the cavity can provide stronger adsorption force underwater than the hemispherical cavity, which is more conducive to the conformal adhesion of the electrode to the skin.

[0099] Example 3:

[0100] Except for the starfish-like tube foot structure and its laser cutting steps, it is the same as in Example 1.

[0101] Reference Figure 6 As shown, the top ring of the suction cup in this embodiment has a micro-pleated structure, and the inner side of the suction cup is a hollow hemispherical structure.

[0102] The laser cutting of a starfish-like tube foot array, as exemplified by this invention, includes the following steps:

[0103] Step 1: Cut the block hydrogel into a solid cylindrical array. The cylinders are 1mm in diameter and 1mm in height. The number of cylinders and the spacing between them are set according to the cylinder diameter.

[0104] Step 2: Use a laser to cut a micro-wrinkle pattern on the surface of the cylinder.

[0105] Step 3: Cut a hemispherical cavity with a diameter of 0.7mm from the top of the solid cylinder.

[0106] Step 4: Cut out a tube-foot-like structure on the outside of the solid cylinder. The height of the suction cup frustum is 0.4 mm, the stem diameter is 0.2 mm, and the height is 1.5 mm.

[0107] Step 5: Arrange circular blind holes at the bottom of another block of hydrogel. The diameter of the blind holes is the same as the diameter of the stem and the depth is 1 mm, forming a 3×2 array.

[0108] Step 6: Insert all the tube foot suction cup arrays into the circular blind holes. The tube foot stems and the block hydrogel are bonded together by the adhesive properties of the hydrogel to form a starfish-like tube foot array.

[0109] Compared with the method in Example 1, Example 3 adds a micro-wrinkle pattern to the top of the suction cup. The advantage is that the micro-wrinkle pattern can increase the contact area between the electrode and the skin, and has a significant effect on increasing underwater adsorption capacity and reducing electrode-skin impedance.

[0110] Example 4:

[0111] Except for the laser cutting of the starfish-like tube feet, the procedure is the same as in Example 1. In this example, the starfish-like tube foot array is directly cut from the bottom of the block hydrogel.

[0112] Reference Figure 7 As shown, the laser cutting of the starfish-like tube foot array in this embodiment of the invention includes the following steps:

[0113] Step 1: Cut the block hydrogel into a solid cylindrical array, with each cylinder having a diameter of 0.7 mm and a height of 1 mm, forming a 5×4 array;

[0114] Step 2: Cut a hemispherical cavity with a diameter of 0.5mm from the top of the solid cylinder.

[0115] Compared with the method in Example 1, Example 3 directly cuts the starfish-like tube foot array at the bottom of the block hydrogel. The advantages are: (1) It saves the laser cutting step and the process of inserting the bionic tube foot gel into the block hydrogel, which improves the integrated processing efficiency and makes the electrode manufacturing process more convenient; (2) It reduces the overall thickness of the electrode and makes it fit better with the skin.

Claims

1. A starfish-inspired tube foot array hydrogel electrode, characterized in that, Including bulk hydrogels and starfish-inspired tube foot arrays; The blocky hydrogel and the starfish-like tube foot array are made of the same hydrogel. The starfish-like tube foot array includes multiple tube feet, each tube foot including a stem and a suction cup. The stem is a solid cylinder, and the suction cup is a cup-shaped structure. One end of the stem is the suction cup. The inner side of the suction cup contains an outwardly protruding hemisphere, and the remaining area is the suction cup cavity. The bottom surface of the blocky hydrogel is arranged with a circular blind hole array. The number of circular blind holes is the same as the number of starfish tube feet, and the radius of the circular blind holes is the same as the radius of the starfish tube foot stem. The other end of the stem of each tube foot is inserted into a circular blind hole and bonded to the block hydrogel through the adhesiveness of the hydrogel itself, forming a starfish-like tube foot array. The starfish-inspired tube foot array hydrogel electrode is used for underwater electromyography signal acquisition.

2. The starfish-inspired tube foot array hydrogel electrode according to claim 1, characterized in that, The top ring of the suction cup has a micro-pleated structure.

3. A method for preparing a hydrogel electrode as described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare the prepolymer; Step 2: Add cationic monomers, anionic monomers, and potassium persulfate to the prepolymer and heat at 80 °C for 3-4 hours; Step 3: Laser cutting of the gel yields the tube feet, including the stem and suckers; Step 4: Laser cut the bottom of the blocky gel to obtain a circular blind hole array; Step 5: Insert the stems of all the tube feet into the circular blind holes and bond them to the block hydrogel through the adhesiveness of the hydrogel itself to form a starfish-like tube foot array.

4. The preparation method according to claim 3, characterized in that, Step 1 specifically involves: Step 1-1: Dissolve N,N′-methylenebisacrylamide, sodium dodecyl sulfate, and potassium persulfate in deionized water to prepare three raw material solutions; Step 1-2: Mix the three raw material solutions prepared in Step 1-1 with cationic monomers or anionic monomers and polyethylene glycol methyl ether acrylate, and react at 70 degrees Celsius for 30 minutes at a speed of 300 rpm to obtain the prepolymer.

5. The preparation method according to claim 4, characterized in that, In steps 1-2, the mass ratio of cationic monomer, polyethylene glycol methyl ether acrylate, N,N′-methylenebisacrylamide dodecyl sulfate, potassium persulfate, and sodium dodecyl sulfate is 1430:1200:77:25:270, with the mass unit being mg.

6. The preparation method according to claim 3, characterized in that, In step 2, the volume ratio of cationic monomer, anionic monomer, prepolymer, and potassium persulfate is 227:104:500:60, with the volume unit being μL.

7. The preparation method according to claim 3, characterized in that, The blocky hydrogel is 4–9 mm long, 3–9 mm wide, and 3 mm high, with a blind hole depth of 1 mm.

8. The preparation method according to claim 3, characterized in that, The suction cup has a frustum structure on the outside and a hollow hemisphere on the inside. The outer diameter of the suction cup is 0.7–1 mm, the inner diameter is 0.5–0.8 mm, and the height is 0.5–0.8 mm. The stem diameter is 0.2–0.5 mm and the height is 1–1.5 mm.

9. The preparation method according to claim 3, characterized in that, The suction cup has a frustum structure on the outside and a hollow hemisphere on the inside. The suction cup has an outer diameter of 0.7 mm, an inner diameter of 0.5 mm, and a height of 0.5 mm. The stem has a diameter of 0.2 mm and a height of 1.5 mm.

Images