Hydrogel electrode with embedded super-hydrophobic / conductive coating as well as preparation method and application of hydrogel electrode

Abstract

The invention discloses a hydrogel electrode with an embedded super-hydrophobic / conductive coating, which is characterized in that a carbon black / hydrogel composite electrode is used as a solid substrate, and then a CNTs coating is constructed on the surface of the carbon black / hydrogel composite electrode through a monomolecular layer membrane technology; then vinyl-terminated polydimethylsiloxane (Vi-PDMS), pentaerythritol tetra-3-mercaptopropionate (PETMP) and benzoin dimethyl ether (DMPA) are uniformly mixed in a dichloromethane solution, and the mixture is sprayed on the surface of the CNTs coating, so that a CNTs / Vi-PDMS / PETMP coating is formed, and the hydrogel electrode with the embedded super-hydrophobic / conductive coating is formed. The problems of unstable structure and reduced sensing performance caused by expansion of hydrogel and loss of conductive components due to diffusion of the hydrogel on an interface in a water environment in the prior art are solved. The invention further discloses a preparation method and application of the hydrogel electrode with the embedded super-hydrophobic / conductive coating.

Description

Technical Field

[0001] This invention belongs to the field of hydrogel electrode fabrication technology, and relates to hydrogel electrodes with embedded superhydrophobic / conductive coatings. This invention also relates to a method for fabricating the above-mentioned hydrogel electrodes with embedded superhydrophobic / conductive coatings, and to the application of hydrogel electrodes with embedded superhydrophobic / conductive coatings in the field of underwater wearable flexible sensors. Background Technology

[0002] Conductive hydrogels, due to their skin-like elastic modulus, are often used as interfaces in bioelectronics and in contact with human skin. Examples include wearable and implantable electronics, biosensors, bioactuators, health recording electrodes, and medical patches. Traditional conductive hydrogels are typically based on hydrated matrices of conductive polymers, such as polyaniline, polypyrrole, and poly(3,4-ethylenedioxy)thiophene; however, their poor strength / flexibility limits practical applications. Furthermore, the durability of hydrogels at high and low temperatures is a challenge in practical applications. High temperatures cause hydrogels to dry out, while low temperatures cause them to freeze. Introducing glycerol into the hydrogel offers a viable method to prevent moisture loss. Glycerol forms strong hydrogen bonds with water molecules, competing with hydrogen bonds in water, and disrupts ice lattice formation at low temperatures, while preventing water evaporation at high temperatures.

[0003] In recent years, many tough and conductive hydrogels have been developed by incorporating conductive polymers, carbon-based nanomaterials, and metal nanomaterials into strong polymer networks. Among them, superconducting carbon black (CB) nanocomposite hydrogels are soft conductive materials with excellent electrical and mechanical properties, showing great application potential in biomedical engineering. However, compared with the widespread application of traditional conductive hydrogels in air environments, their underwater sensing applications are significant but still present certain challenges. In aquatic environments, the diffusion of hydrogels at the interface leads to hydrogel expansion and loss of conductive components, resulting in structural instability and decreased sensing performance. Although significant efforts have been made to improve the water resistance of conductive gels and apply them to underwater wearable sensing, and some encouraging results have been achieved, significant challenges remain regarding the safety and efficiency of efficient underwater activities. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrogel electrode with an embedded superhydrophobic / conductive coating, which solves the problem in the prior art where the diffusion of hydrogel at the interface in an aqueous environment leads to the expansion of the hydrogel and the loss of conductive components, resulting in structural instability and decreased sensing performance.

[0005] Another object of the present invention is to provide a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating.

[0006] A third objective of this invention is to provide applications for hydrogel electrodes with embedded superhydrophobic / conductive coatings.

[0007] The technical solution adopted in this invention is a hydrogel electrode with an embedded superhydrophobic / conductive coating. A carbon black / hydrogel composite electrode is used as a solid substrate. Then, a CNTs coating is constructed on the surface of the carbon black / hydrogel composite electrode using monolayer film technology. Then, vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are uniformly mixed in a dichloromethane solution and sprayed onto the surface of the CNTs coating to form a CNTs / Vi-PDMS / PETMP coating, thus constituting a hydrogel electrode with an embedded superhydrophobic / conductive coating.

[0008] The second technical solution adopted in this invention is a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating, which is implemented according to the following steps: Step 1: Prepare carbon black / hydrogel composite electrode; Step 2: A CNT film is constructed at the air / water interface using monolayer film technology, and then the CNT film is transferred to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating. Step 3: Vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are uniformly mixed in dichloromethane solution to obtain a mixture. A certain amount of the mixture is sprayed onto the CNTs coating surface to construct a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface. Step 4: After photocuring the CNTs / Vi-PDMS / PETMP coating, a hydrogel electrode with an embedded superhydrophobic / conductive coating is obtained.

[0009] Furthermore, step 1 specifically involves: Step 1.1, Preparation of carbon black / hydrogel suspension Carbon black powder and dopamine hydrochloride were added to NaOH solution and stirred evenly to obtain a carbon black suspension. Then, N'N-methylenebisacrylamide, acrylamide, ammonium persulfate, polyethylene glycol diacrylate, acrylic acid and glycerol were added to the carbon black suspension and mixed to obtain a carbon black / hydrogel suspension. Step 1.2: After vacuum treatment of the carbon black / hydrogel suspension, it is poured into a polytetrafluoroethylene mold for film formation to obtain the carbon black / hydrogel composite electrode.

[0010] Furthermore, step 1.1 specifically includes: Step 1.1.1: Prepare a carbon black solution of 0.1-1 mg / mL using deionized water with pH 7.8-8.5 as the solvent. Sonicate the solution at room temperature for 25-30 min, then add dopamine hydrochloride at a mass ratio of 1:1 to the carbon black. Stir magnetically in an oil bath at 50-60℃ for 10-15 h. After cooling, sonicate again for 20-30 min to obtain a carbon black suspension. The molecular weight of dopamine hydrochloride is 189.64 MW. Step 1.1.2: Add 3-10 mg of N'N-methylenebisacrylamide and 0.5-0.75 g of ammonium persulfate to 10 mL of carbon black suspension, then add 10-15 g of acrylamide, 100-150 μL of polyethylene glycol diacrylate, and 300-400 μL of acrylic acid. Stir magnetically at room temperature for 5-10 min to obtain a mixture. Then add 5-10 mL of glycerol to the mixture and stir magnetically for 5-10 min and sonicate for 10-20 min to obtain a carbon black / hydrogel suspension.

[0011] Furthermore, the vacuum treatment in step 1.2 specifically involves placing the polytetrafluoroethylene mold of the prepared carbon black / hydrogel suspension in a vacuum oven at a temperature of 20-25℃ and a vacuum degree of 0.6-0.8KPa, and letting it stand for 2-3 hours before taking it out for use.

[0012] Furthermore, the film-forming treatment in step 1.2 specifically includes: The vacuum-treated carbon black / hydrogel suspension is poured into a polytetrafluoroethylene (PTFE) mold. The liquid thickness is controlled to be 0.5-50 mm using a scraper. The PTFE mold is placed in a 50°C forced-air drying oven for 20-120 min. The mold after film formation is removed, and the carbon black / hydrogel composite electrode is obtained after demolding.

[0013] Furthermore, step 2 specifically involves: Step 2.1, prepare CNTs suspension, specifically: add 1 mg of carbon nanotube powder to 1-10 mL of anhydrous ethanol, sonicate for 30-40 min to obtain CNTs suspension; Step 2.2: Take 5-10 mL of CNT suspension and spray it onto an air / water interface with a diameter of 10-20 cm using monolayer membrane technology to obtain a suspended CNT membrane. Step 2.3: Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the surface of the carbon black / hydrogel composite electrode.

[0014] Furthermore, step 3 specifically involves: Step 3.1: Mix 0.5-5g of vinyl-terminated polydimethylsiloxane (Vi-PDMS), 0.1-1g of pentaerythritol tetra-3-mercaptopropionate (PETMP), and 0.1-0.2g of benzoin dimethyl ether (DMPA) uniformly in 20-200g of dichloromethane solution; Step 3.2: Take 0.2-0.5 mL of the mixture prepared in step 3.1 and spray it onto the CNTs coating surface by spraying, thereby constructing a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface.

[0015] Furthermore, photocuring specifically involves: The prepared CNTs / Vi-PDMS / PETMP coating was irradiated with ultraviolet light. The center wavelength of the ultraviolet light was 360-370 nm, the irradiation time was 1-20 min, and the ultraviolet light intensity was 10-50 mW / cm². 2 .

[0016] The third technical solution adopted in this invention is the application of hydrogel electrodes with embedded superhydrophobic / conductive coatings, which applies the aforementioned hydrogel electrodes with embedded superhydrophobic / conductive coatings to the field of underwater wearable flexible sensors.

[0017] The beneficial effects of this invention are: (1) The present invention forms a superhydrophobic polymer network structure on the surface of hydrogel through the thiol-alkenyl click chemistry of vinyl-terminated polydimethylsiloxane (Vi-PDMS) and pentaerythritol tetra-3-mercaptopropionate (PETMP); in addition, acrylamide in the hydrogel can also undergo click chemical reaction with pentaerythritol tetra-3-mercaptopropionate, which enables the superhydrophobic coating to be firmly bonded to the hydrogel substrate.

[0018] (2) The “embedded” conductive / superhydrophobic coating can improve the underwater anti-swelling performance of the hydrogel electrode without changing the intrinsic properties of the hydrogel electrode. Furthermore, the conductive network of the carbon nanotube layer and the conductive network of the carbon black can achieve the strain synergistic effect of the electrical signal, thereby improving the adaptability of the hydrogel electrode. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to the present invention; Figure 2 This is an infrared spectrum of the thiol-alkenyl click chemistry of vinyl-terminated polydimethylsiloxane (Vi-PDMS) and pentaerythritol tetra-3-mercaptopropionate (PETMP) in Example 4 of this invention. Figure 3This is an infrared spectrum of the thiol-alkenyl click chemistry of acrylamide (AM) and pentaerythritol tetra-3-mercaptopropionate (PETMP) in Example 4 of the present invention. Figure 4 The conductivity test graphs are of the carbon black / hydrogel electrode, the hydrogel electrode with CNTs constructed, and the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in Example 4 of the present invention. Figure 5 This is a graph showing the electrical stability of the hydrogel electrode with an embedded superhydrophobic / conductive coating in an underwater environment in Embodiment 4 of the present invention. Figure 6 This is a strain response sensitivity diagram of the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in Example 4 of the present invention. Figure 7 The contact angle test diagrams are of the carbon black / hydrogel electrode prepared in Example 4 of the present invention, the carbon black / hydrogel electrode that constructs CNTs, and the hydrogel electrode with an embedded superhydrophobic / conductive coating. Figure 8 This is a superhydrophobic stability test diagram of the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in Example 4 of the present invention. Detailed Implementation

[0020] The following detailed description is provided in conjunction with specific implementation methods.

[0021] Example 1 This invention relates to a hydrogel electrode with an embedded superhydrophobic / conductive coating. A carbon black / hydrogel composite electrode is used as a solid substrate. A CNTs coating is then constructed on the surface of the carbon black / hydrogel composite electrode using monolayer film technology. Vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are then uniformly mixed in a dichloromethane solution and sprayed onto the CNTs coating surface to form a CNTs / Vi-PDMS / PETMP coating, thus constituting a hydrogel electrode with an embedded superhydrophobic / conductive coating.

[0022] Example 2 The present invention discloses a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating. The preparation of the hydrogel electrode with an embedded superhydrophobic / conductive coating in Example 1 is carried out according to the following steps: Step 1, preparing the carbon black / hydrogel composite electrode, specifically: Step 1.1, Preparation of carbon black / hydrogel suspension Carbon black powder and dopamine hydrochloride were added to NaOH solution and stirred until homogeneous to obtain a carbon black suspension. Then, N'N-methylenebisacrylamide, acrylamide, ammonium persulfate, polyethylene glycol diacrylate, acrylic acid, and glycerol were added to the carbon black suspension and mixed to obtain a carbon black / hydrogel suspension. Specifically: Step 1.1.1: Prepare a carbon black solution of 0.1-1 mg / mL using deionized water at pH 8.0 as the solvent. Sonicate the solution at room temperature for 25-30 min, then add dopamine hydrochloride at a mass ratio of 1:1 to the carbon black. Stir magnetically in an oil bath at 50-60℃ for 10-15 h. After cooling, sonicate again for 20-30 min to obtain a carbon black suspension. The molecular weight of dopamine hydrochloride is 189.64 MW. Step 1.1.2: Add 3-10 mg of N'N-methylenebisacrylamide and 0.5-0.75 g of ammonium persulfate to 10 mL of carbon black suspension, then add 10-15 g of acrylamide, 100-150 μL of polyethylene glycol diacrylate, and 300-400 μL of acrylic acid. Stir magnetically at room temperature for 5-10 min to obtain a mixture. Then add 5-10 mL of glycerol to the mixture and stir magnetically for 5-10 min and sonicate for 10-20 min to obtain a carbon black / hydrogel suspension. Step 1.2: After vacuum treatment of the carbon black / hydrogel suspension, it is poured into a polytetrafluoroethylene mold for film formation to obtain the carbon black / hydrogel composite electrode. The vacuum treatment specifically involves placing the polytetrafluoroethylene mold of the prepared carbon black / hydrogel suspension in a vacuum oven at a temperature of 20-25℃ and a vacuum degree of 0.6-0.8KPa, and letting it stand for 2-3 hours before taking it out for use. The film-forming treatment specifically includes: The vacuum-treated carbon black / hydrogel suspension is poured into a polytetrafluoroethylene mold. The liquid thickness is controlled to be 0.5-50 mm using a scraper. The polytetrafluoroethylene mold is placed in a 50°C forced-air drying oven for 20-120 min. The mold after film formation is removed, and the carbon black / hydrogel composite electrode is obtained after demolding. Step 2 involves constructing a CNT film at the air / water interface using monolayer film technology, and then transferring the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating; specifically: Step 2.1, prepare CNTs suspension, specifically: add 1 mg of carbon nanotube powder to 1-10 mL of anhydrous ethanol, sonicate for 30-40 min to obtain CNTs suspension; Step 2.2: Take 5-10 mL of CNT suspension and spray it onto an air / water interface with a diameter of 10-20 cm using monolayer membrane technology to obtain a suspended CNT membrane. Step 2.3: Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the surface of the carbon black / hydrogel composite electrode. Step 3: Vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are uniformly mixed in a dichloromethane solution to obtain a mixture. A certain amount of the mixture is sprayed onto the CNTs coating surface to construct a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface. Specifically: Step 3.1: Mix 0.5-5g of vinyl-terminated polydimethylsiloxane Vi-PDMS, 0.1-1g of pentaerythritol tetra-3-mercaptopropionate PETMP, and 0.1-0.2g of benzoin dimethyl ether DMPA uniformly in 20-200g of dichloromethane solution; Step 3.2: Take 0.2-0.5 mL of the mixture prepared in step 3.1 and spray it onto the CNTs coating surface by spraying, thereby constructing a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface. Step 4: After photocuring the CNTs / Vi-PDMS / PETMP coating, a hydrogel electrode with an embedded superhydrophobic / conductive coating is obtained. The photocuring process specifically involves: The prepared CNTs / Vi-PDMS / PETMP coating was irradiated with ultraviolet light. The center wavelength of the ultraviolet light was 365 nm, the irradiation time was 1-20 min, and the ultraviolet light intensity was 10-50 mW / cm². 2 .

[0023] The superhydrophobic / conductive coating includes an embedded carbon nanotube (CNT) coating, a vinyl-terminated polydimethylsiloxane solution (Vi-PDMS) and a pentaerythritol tetra-3-mercaptopropionate (PETMP) superhydrophobic coating, wherein the thiol-ene click chemistry of Vi-PDMS and PETMP can form a polymer interpenetrating network in the embedded carbon nanotube (CNT) coating; in addition, the thiol-ene click chemistry of acrylamide (AM) and pentaerythritol tetra-3-mercaptopropionate (PETMP) can firmly stabilize the embedded CNT conductive layer on the surface of the carbon black / hydrogel composite electrode.

[0024] The photocuring process triggers various thiol-alkene click chemistry reactions: Superhydrophobic coating: Benzoin dimethyl ether (DMPA) acts as a photoinitiator in dichloromethane solution, catalyzing a thiol-ene click chemistry reaction between vinyl-terminated polydimethylsiloxane (Vi-PDMS) and pentaerythritol tetra-3-mercaptopropionate (PETMP) to form a polymer interpenetrating network on the surface of the carbon nanotube coating. Interface layer: Photoinitiator activates acrylamide (AM), which can also undergo thiol-ene click chemistry with pentaerythritol tetra-3-mercaptopropionate (PETMP) to form a stable interfacial adhesion layer at the interface between CNTs and hydrogel electrode.

[0025] Example 3 The present invention relates to the application of hydrogel electrodes with embedded superhydrophobic / conductive coatings, specifically the application of the hydrogel electrodes with embedded superhydrophobic / conductive coatings prepared in Example 2 in the field of underwater wearable flexible sensors.

[0026] Example 4 The present invention discloses a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating, the process of which is as follows: Figure 1 As shown, the specific steps are as follows: Step 1: (a) Add 10 mg of carbon black particles to 10 mL of NaOH solution with pH=8.0, sonicate at room temperature for 30 min, then add dopamine hydrochloride (molecular weight 189.64MW) in a mass ratio of 1:1 with carbon black to the above solution, stir magnetically in an oil bath at 50 °C for 15 h, cool and sonicate again for 30 min to obtain a carbon black suspension; (b) 3 mg N'N-methylenebisacrylamide (BIS) and 0.75 g ammonium persulfate (APS) were added to 10 mL of carbon black suspension; then 10 g acrylamide (AM), 150 μL polyethylene glycol diacrylate (PEGDA), and 400 μL acrylic acid (AA) were added, and the mixture was magnetically stirred at room temperature for 5 min; then 10 mL glycerol was added to the mixture, and the mixture was magnetically stirred for 10 min and sonicated for 20 min to obtain a carbon black / hydrogel suspension. Step 2: Place the carbon black / hydrogel suspension in a vacuum oven for vacuum treatment at a temperature of 20°C and a vacuum degree of 0.8 kPa. After standing for 2 hours, remove the suspension and pour it into a polytetrafluoroethylene mold. Use a scraper to control the liquid thickness to 1 mm. Place the mold in a 50°C forced-air drying oven for 20 minutes. Remove the mold after film formation and demold to obtain the carbon black / hydrogel composite electrode.

[0027] Step 3: (a) Prepare a carbon nanotube / anhydrous ethanol suspension by adding 1 mg of carbon nanotube powder to 1 mL of anhydrous ethanol and sonicating for 30 min to obtain a CNT suspension. (b) Take 5 mL of the above CNTs suspension and spray it onto an air / water interface with a diameter of 10 cm to obtain a suspended CNTs film. (c) Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the electrode surface; Step 4: (a) Mix 0.5g of vinyl-terminated polydimethylsiloxane (Vi-PDMS), 0.1g of pentaerythritol tetra-3-mercaptopropionate (PETMP), and 0.2g of benzoin dimethyl ether (DMPA) uniformly in 20g of dichloromethane solution to obtain a mixture. Take 0.2mL of the mixture and spray it onto the surface of the embedded CNTs coating to construct an embedded CNTs / Vi-PDMS / PETMP coating on the surface of the carbon black / hydrogel composite electrode. Step 5: Irradiate the fabricated "embedded" CNTs / Vi-PDMS / PETMP coating with ultraviolet light at a center wavelength of 365nm for 10 minutes. The intensity of the ultraviolet light is 10-50mW / cm². 2 A hydrogel electrode with an embedded superhydrophobic / conductive coating was obtained.

[0028] The thiol-alkenyl click chemistry reaction of vinyl-terminated polydimethylsiloxane (Vi-PDMS) and pentaerythritol tetra-3-mercaptopropionate (PETMP) in this embodiment was subjected to infrared spectroscopy, and the infrared spectrum was obtained, as shown in the figure. Figure 2 As shown, the disappearance of the thiol groups in the vinyl group of vinyl-terminated polydimethylsiloxane (Vi-PDMS) and pentaerythritol tetra-3-mercaptopropionate (PETMP) demonstrates that a click chemical reaction occurs, constructing a superhydrophobic surface.

[0029] The thiol-alkenyl click chemistry reaction of acrylamide (AM) and pentaerythritol tetra-3-mercaptopropionate (PETMP) in this embodiment was subjected to infrared spectroscopy, and the infrared spectrum was obtained, as shown below. Figure 3 As shown, the vinyl group of acrylamide (AM) disappears after reacting with the thiol group in pentaerythritol tetra-3-mercaptopropionate (PETMP), proving that pentaerythritol tetra-3-mercaptopropionate (PETMP) can undergo a click chemical reaction with acrylamide (AM) inside the hydrogel to form an embedded superhydrophobic coating.

[0030] The carbon black / hydrogel electrode prepared in this embodiment, the carbon black / hydrogel electrode with CNT coating, and the hydrogel electrode with embedded superhydrophobic / conductive coating were subjected to electrical performance tests, such as... Figure 4As shown, compared with the carbon black / hydrogel electrode, the conductivity of the carbon black / hydrogel electrode after the CNTs coating is greatly improved, proving that the CNTs coating can be embedded inside the carbon black / hydrogel electrode and has a good enhancement effect on electrical performance. The conductivity did not decrease significantly after spraying the Vi-PDMS / PETMP superhydrophobic coating, proving that the coating has almost no effect on electrical performance.

[0031] The underwater environmental electrical performance of the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in this embodiment was tested, and the results are as follows: Figure 5 As shown, the hydrogel electrode with an embedded superhydrophobic / conductive coating can maintain stability in an underwater environment and suppress the underwater swelling of carbon black / hydrogel.

[0032] The strain response sensitivity of the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in this embodiment was tested, and the results are as follows: Figure 6 As shown, the prepared hydrogel electrode with an embedded superhydrophobic / conductive coating exhibits good linear response sensitivity and shows promising potential in the field of smart wearables. Contact angle tests were performed on the carbon black / hydrogel electrode, the carbon black / hydrogel electrode with a CNT coating, and the hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in this embodiment. Figure 7 As shown, the embedded CNTs / Vi-PDMS / PETMP coating exhibits excellent superhydrophobic properties, which can stabilize the electrical and sensing performance of the hydrogel electrode.

[0033] The hydrogel electrode with an embedded superhydrophobic / conductive coating prepared in this embodiment was tested for waterproof performance, and the results are as follows: Figure 8 As shown, the wettability of carbon black / hydrogel electrodes, carbon black / hydrogel electrodes with CNTs, and hydrogel electrodes with embedded superhydrophobic / conductive coatings were tested. The results show that the contact angle of the hydrogel electrode with embedded superhydrophobic / conductive coatings is >150° and can maintain good superhydrophobic performance stability.

[0034] Example 5 The present invention discloses a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating, which is implemented according to the following steps: Step 1: (a) Add 5 mg of carbon black particles to 10 mL of NaOH solution with pH=8.0, sonicate at room temperature for 30 min, then add dopamine hydrochloride (molecular weight 189.64MW) in a mass ratio of 1:1 with carbon black to the above solution, stir magnetically in an oil bath at 50℃ for 15 h, cool and sonicate again for 30 min to obtain carbon black suspension; (b) Add 3 mg N'N-methylenebisacrylamide (BIS) and 0.75 g ammonium persulfate (APS) to 10 mL of carbon black suspension, then add 12.5 g acrylamide (AM), 150 μL polyethylene glycol diacrylate (PEGDA), and 400 μL acrylic acid (AA), and stir magnetically at room temperature for 10 min; then add 10 mL glycerol to the mixture, and stir magnetically for 10 min and sonicate for 20 min to obtain carbon black / hydrogel suspension; Step 2: Place the carbon black / hydrogel suspension in a vacuum oven for vacuum treatment at a temperature of 20°C and a vacuum degree of 0.8 kPa. After standing for 2 hours, pour the carbon black / hydrogel suspension into a polytetrafluoroethylene mold. Use a scraper to control the liquid thickness to 1 mm. Place the mold in a 50°C forced-air drying oven for 20 minutes. Remove the mold after film formation. After demolding, the carbon black / hydrogel composite electrode is obtained.

[0035] Step 3: (a) Prepare a carbon nanotube / anhydrous ethanol suspension by adding 1 mg of carbon nanotube powder to 1 mL of anhydrous ethanol and sonicating for 30 min to obtain a CNT suspension. (b) Take 5 mL of the above suspension and spray it onto an air / water interface with a diameter of 10 cm to obtain a suspended CNT film. (c) Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the electrode surface; Step 4: (a) Mix 0.5g of vinyl-terminated polydimethylsiloxane (Vi-PDMS), 0.5g of pentaerythritol tetra-3-mercaptopropionate (PETMP), and 0.2g of benzoin dimethyl ether (DMPA) uniformly in 20g of dichloromethane solution to obtain a mixture. Take 0.2mL of the mixture and spray it onto the surface of the embedded CNTs coating to construct an embedded CNTs / Vi-PDMS / PETMP coating on the surface of the carbon black / hydrogel composite electrode. Step 5: Irradiate the fabricated "embedded" CNTs / Vi-PDMS / PETMP coating with ultraviolet light at a center wavelength of 365nm for 10 minutes. The intensity of the ultraviolet light is 10-50mW / cm². 2 A hydrogel electrode with an embedded superhydrophobic / conductive coating was obtained.

[0036] Example 6 The present invention discloses a method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating, which is implemented according to the following steps: Step 1: (a) Add 10 mg of carbon black particles to 10 mL of NaOH solution with pH=8.0, sonicate at room temperature for 30 min, then add dopamine hydrochloride (molecular weight 189.64MW) in a mass ratio of 1:1 with carbon black to the above solution, stir magnetically in an oil bath at 50 °C for 15 h, cool and sonicate again for 30 min to obtain a carbon black suspension; (b) 10 mg N'N-methylenebisacrylamide (BIS) and 0.75 g ammonium persulfate (APS) were added to 10 mL of carbon black suspension, followed by the addition of 15 g acrylamide (AM), 150 μL polyethylene glycol diacrylate (PEGDA), and 400 μL acrylic acid (AA). The mixture was then magnetically stirred at room temperature for 10 min. 10 mL of glycerol was then added to the mixture, and the mixture was magnetically stirred for 10 min and sonicated for 20 min to obtain a carbon black / hydrogel suspension. Step 2: Place the carbon black / hydrogel suspension in a vacuum oven for vacuum treatment. The oven temperature is 20℃ and the vacuum degree is 0.8KPa. After standing for 2 hours, pour the carbon black / hydrogel suspension into a polytetrafluoroethylene mold. Use a scraper to control the liquid thickness to 1mm. Place the mold in a 50℃ forced-air drying oven for 20 minutes. Take out the mold after film formation. After demolding, the carbon black / hydrogel composite electrode is obtained. Step 3: (a) Prepare a carbon nanotube / anhydrous ethanol suspension by adding 1 mg of carbon nanotube powder to 5 mL of anhydrous ethanol and sonicating for 30 min to obtain a CNT suspension. (b) Take 5 mL of the above suspension and spray it onto an air / water interface with a diameter of 10 cm to obtain a suspended CNT film. (c) Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the electrode surface; Step 4: (a) Mix 0.5g of vinyl-terminated polydimethylsiloxane (Vi-PDMS), 0.5g of pentaerythritol tetra-3-mercaptopropionate (PETMP), and 0.2g of benzoin dimethyl ether (DMPA) uniformly in 20g of dichloromethane solution to obtain a mixture, and take 0.5mL of the mixture to spray onto the surface of the embedded CNTs coating to construct an embedded CNTs / Vi-PDMS / PETMP coating on the surface of the carbon black / hydrogel composite electrode; Step 5: Irradiate the fabricated "embedded" CNTs / Vi-PDMS / PETMP coating with ultraviolet light at a center wavelength of 365nm for 10 minutes. The intensity of the ultraviolet light is 10-50mW / cm². 2 A hydrogel electrode with an embedded superhydrophobic / conductive coating was obtained.

Claims

1. A hydrogel electrode with an embedded superhydrophobic / conductive coating, characterized in that, A carbon black / hydrogel composite electrode is used as a solid substrate. Then, a CNTs coating is constructed on the surface of the carbon black / hydrogel composite electrode using monolayer film technology. Then, vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are uniformly mixed in dichloromethane solution and sprayed onto the surface of the CNTs coating to form a CNTs / Vi-PDMS / PETMP coating, which constitutes a hydrogel electrode with an embedded superhydrophobic / conductive coating.

2. A method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating, characterized in that, The specific steps are as follows: Step 1: Prepare carbon black / hydrogel composite electrode; Step 2: A CNT film is constructed at the air / water interface using monolayer film technology, and then the CNT film is transferred to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating. Step 3: Vinyl-terminated polydimethylsiloxane Vi-PDMS, pentaerythritol tetra-3-mercaptopropionate PETMP, and benzoin dimethyl ether DMPA are uniformly mixed in dichloromethane solution to obtain a mixture. A certain amount of the mixture is sprayed onto the CNTs coating surface to construct a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface. Step 4: After photocuring the CNTs / Vi-PDMS / PETMP coating, a hydrogel electrode with an embedded superhydrophobic / conductive coating is obtained.

3. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 2, characterized in that, Step 1 specifically involves: Step 1.1, Preparation of carbon black / hydrogel suspension Carbon black powder and dopamine hydrochloride were added to NaOH solution and stirred evenly to obtain a carbon black suspension. Then, N'N-methylenebisacrylamide, acrylamide, ammonium persulfate, polyethylene glycol diacrylate, acrylic acid and glycerol were added to the carbon black suspension and mixed to obtain a carbon black / hydrogel suspension. Step 1.2: After vacuum treatment of the carbon black / hydrogel suspension, it is poured into a polytetrafluoroethylene mold for film formation to obtain the carbon black / hydrogel composite electrode.

4. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 3, characterized in that, Step 1.1 specifically includes: Step 1.1.1: Prepare a carbon black solution of 0.1-1 mg / mL using deionized water at pH 8.0 as the solvent. Sonicate the solution at room temperature for 25-30 min, then add dopamine hydrochloride at a mass ratio of 1:1 to the carbon black. Stir magnetically in an oil bath at 50-60℃ for 10-15 h. After cooling, sonicate again for 20-30 min to obtain a carbon black suspension. The molecular weight of dopamine hydrochloride is 189.64 MW. Step 1.1.2: Add 3-10 mg of N'N-methylenebisacrylamide and 0.5-0.75 g of ammonium persulfate to 10 mL of carbon black suspension, then add 10-15 g of acrylamide, 100-150 μL of polyethylene glycol diacrylate, and 300-400 μL of acrylic acid. Stir magnetically at room temperature for 5-10 min to obtain a mixture. Then add 5-10 mL of glycerol to the mixture and stir magnetically for 5-10 min and sonicate for 10-20 min to obtain a carbon black / hydrogel suspension.

5. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 4, characterized in that, The vacuum treatment in step 1.2 specifically involves placing the polytetrafluoroethylene mold of the prepared carbon black / hydrogel suspension in a vacuum oven at a temperature of 20-25°C and a vacuum degree of 0.6-0.8 kPa, and letting it stand for 2-3 hours before taking it out for use.

6. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 5, characterized in that, The film-forming treatment in step 1.2 specifically includes: The vacuum-treated carbon black / hydrogel suspension is poured into a polytetrafluoroethylene (PTFE) mold. The liquid thickness is controlled to be 0.5-50 mm using a scraper. The PTFE mold is placed in a 50°C forced-air drying oven for 20-120 min. The mold after film formation is removed, and the carbon black / hydrogel composite electrode is obtained after demolding.

7. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 1, characterized in that, Step 2 specifically involves: Step 2.1, prepare CNTs suspension, specifically: add 1 mg of carbon nanotube powder to 1-10 mL of anhydrous ethanol, sonicate for 30-40 min to obtain CNTs suspension; Step 2.2: Take 5-10 mL of CNT suspension and spray it onto an air / water interface with a diameter of 10-20 cm using monolayer membrane technology to obtain a suspended CNT membrane. Step 2.3: Transfer the CNT film to the surface of the carbon black / hydrogel composite electrode to form an embedded CNT coating structure on the surface of the carbon black / hydrogel composite electrode.

8. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 7, characterized in that, Step 3 specifically involves: Step 3.1: Mix 0.5-5g of vinyl-terminated polydimethylsiloxane Vi-PDMS, 0.1-1g of pentaerythritol tetra-3-mercaptopropionate PETMP, and 0.1-0.2g of benzoin dimethyl ether DMPA uniformly in 20-200g of dichloromethane solution; Step 3.2: Take 0.2-0.5 mL of the mixture prepared in step 3.1 and spray it onto the CNTs coating surface by spraying, thereby constructing a CNTs / Vi-PDMS / PETMP coating on the carbon black / hydrogel composite electrode surface.

9. The method for preparing a hydrogel electrode with an embedded superhydrophobic / conductive coating according to claim 1, characterized in that, The photocuring specifically refers to: The prepared CNTs / Vi-PDMS / PETMP coating was irradiated with ultraviolet light. The center wavelength of the ultraviolet light was 360-370 nm, the irradiation time was 1-20 min, and the ultraviolet light intensity was 10-50 mW / cm². 2 .

10. Application of a hydrogel electrode with an embedded superhydrophobic / conductive coating, characterized in that, The hydrogel electrode with an embedded superhydrophobic / conductive coating as described in any one of claims 1-9 is applied in the field of underwater wearable flexible sensors.

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