Preparation method and application of a strong, frost-resistant and highly conductive composite hydrogel electrode

Abstract

The present invention discloses a method for preparing and applying a tough, frost-resistant, and highly conductive composite hydrogel electrode. The method comprises the following steps: Step 1: Adding nanocellulose (CNF) to deionized water to obtain a uniform dispersed solution; Step 2: Stirring the solution at room temperature to dissolve the solution and obtain a uniform, clear precursor solution; Step 3: Rapidly stirring the solution to obtain a mixed solution; Step 4: Adding N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution obtained in Step 3 and stirring for 15 minutes to obtain a hydrogel precursor solution. After uniform stirring and ultrasonic defoaming, the solution is placed in an oven at 60°C and reacted for 4 hours to obtain a tough, frost-resistant, and highly conductive hydrogel. Beneficial effects: Enhanced conductivity of the hydrogel. The method has the advantages of high sensitivity, high stability, and a wide detection range. It can monitor weak physiological signals and can be used for muscle electrical monitoring, electrocardiogram monitoring, or motion monitoring.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of a composite hydrogel electrode, and in particular to a preparation method and application of a composite hydrogel electrode that is strong, frost-resistant and highly conductive. Background Art

[0002] In today's rapidly developing electronics sector, composite hydrogel electrodes are attracting significant attention due to their potential applications in flexible electronic devices, smart wearables, and biomedical monitoring. These applications place increasingly stringent demands on the performance of electrode materials. For example, in smart wearables, electrodes must possess excellent flexibility and comfort to accommodate the complex movements of different parts of the human body. In biomedical monitoring, electrodes must exhibit good compatibility with human tissue while ensuring accurate and stable signal transmission.

[0003] Hydrogels exhibit numerous advantages. Their high elasticity and stretchability allow them to adapt to varying deformation requirements, allowing them to deform with human movement without affecting their functionality. Their excellent toughness ensures they will not fail due to repeated deformation during long-term use. Their ionic conductivity is adjustable and can be tailored to different application scenarios. Their ion transport mechanism is similar to that in the body, which can improve the accuracy and reliability of flexible sensors in the biomedical field. However, many composite hydrogel electrode materials currently on the market still have limitations. Some hydrogel electrodes are prone to failure in complex environments. For example, when exposed to varying temperatures, especially low temperatures, they may suffer structural damage and performance degradation, seriously limiting their use in cold regions or applications requiring low-temperature storage and transportation. Furthermore, many existing composite hydrogel electrodes fail to meet the required high conductivity, resulting in low signal transmission efficiency and accuracy, limiting their application in highly sensitive electronic devices. Furthermore, some electrode materials have suboptimal mechanical properties, and may break or deform due to external forces during use, affecting their overall performance and service life.

[0004] Based on the above problems, the present invention improves the mechanical properties of the hydrogel by blending acrylamide with nanocellulose and gelatin, and improves the conductivity by introducing the conductive polymer PEDOT:PSS. The prepared composite hydrogel electrode has the advantages of high toughness, frost resistance, antibacterial properties, conductivity and biocompatibility. It is used to prepare strain sensors with high sensitivity, high stability and a wide detection range. Summary of the Invention

[0005] The primary purpose of this invention is to address the difficulty of existing composite hydrogel electrodes in meeting the high conductivity requirement, resulting in low signal transmission efficiency and accuracy, which limits their application in highly sensitive electronic devices. Furthermore, some electrode materials suffer from suboptimal mechanical properties, potentially causing cracking or deformation during use due to external forces, impacting their overall performance and service life. This invention provides a method for preparing and applying a strong, frost-resistant, and highly conductive composite hydrogel electrode.

[0006] The present invention provides a method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode, which comprises the following steps:

[0007] Step 1: Add nanocellulose CNF into deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0008] Step 2: Add acrylamide AM, gelatin Gel and tannic acid TA powder to the binary solvent prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0009] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid PEDOT:PSS solution to the precursor solution prepared in step 2, and rapidly stirring to obtain a mixed solution;

[0010] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution obtained in step 3 and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place the solution in an oven at 60°C for 4 hours to obtain a strong, frost-resistant and highly conductive hydrogel.

[0011] The concentration of nanocellulose in step 1 is 5 wt %, and the concentration of dimethyl sulfoxide is 35 wt %.

[0012] In step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 0-20 wt % of acrylamide, and the concentration of tannic acid is 0-10 wt % of acrylamide.

[0013] The concentration of the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate PEDOT:PSS solution in step 3 is 2 wt %.

[0014] The amounts of N,N'-methylenebisacrylamide MBA and ammonium persulfate APS in step 4 are 0.1% and 1% of the mass of acrylamide.

[0015] The strong, frost-resistant and highly conductive composite hydrogel electrode prepared by the above method can be used as a strain sensor in muscle electricity monitoring, electrocardiogram monitoring or motion monitoring.

[0016] Beneficial effects of the present invention:

[0017] The present invention provides a tough, freeze-resistant and highly conductive composite hydrogel electrode. Under the action of the initiator ammonium persulfate (APS), acrylamide forms a polyacrylamide network structure through the cross-linking agent N,N'-methylenebisacrylamide (MBA). As the overall framework, the gelatin molecules are partially cross-linked by tannic acid. The phenolic hydroxyl groups of tannic acid act as hydrogen donors and establish abundant hydrogen bonds with the carboxyl and amine groups of gelatin as hydrogen acceptors, forming a double network structure with polyacrylamide. The amino groups of acrylamide form hydrogen bonds with the phenolic hydroxyl groups of tannic acid, thereby enhancing the mechanical strength of the composite hydrogel. At the same time, by introducing PEDOT:PSS, electrostatic interactions can be formed with some charged components in the hydrogel. In addition, the PSS chain can also form a hydrogen bond network with the hydrogel polymer through the sulfonic acid group, thereby constructing a three-dimensional conductive network and enhancing the conductivity of the hydrogel. By introducing DMSO, the high-temperature water retention and low-temperature freeze resistance of the hydrogel are improved, and the material has good stability in the temperature range of -40 degrees Celsius to 60 degrees Celsius.

[0018] The present invention uses strong, frost-resistant and highly conductive composite hydrogel electrodes to assemble into a flexible strain sensor, which has the advantages of high sensitivity, high stability and a wide detection range.

[0019] The preparation method of the present invention is simple and can realize the monitoring of weak physiological signals. The tough, freeze-resistant and highly conductive composite hydrogel electrode provided by the present invention can be used for muscle electricity monitoring, electrocardiogram monitoring or motion monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the preparation method of the composite hydrogel of the present invention.

[0021] Figure 2 Schematic diagram of the stress-strain curves of the samples described in the present invention at different Gel contents.

[0022] Figure 3 Schematic diagram of the stress-strain curve of the sample described in the present invention under cyclic stretching under external force.

[0023] Figure 4 Schematic diagram of the adhesion strength of the samples of the present invention to different materials.

[0024] Figure 5 Schematic diagram of the resistance change of the sample described in the present invention under different strains.

[0025] Figure 6 Schematic diagram of the resistance change of the sample described in the present invention under repeated cycles under the same strain.

[0026] Figure 7 This is a schematic diagram of the sample described in the present invention being used to monitor physiological signals of human muscle electricity.

[0027] Figure 8 This is a schematic diagram of the sample described in the present invention being used to monitor physiological signals of human electrocardiogram. DETAILED DESCRIPTION

[0028] See also Figures 1 to 8 As shown:

[0029] Example 1:

[0030] The present embodiment provides a method for preparing a tough, freeze-resistant and highly conductive composite hydrogel electrode, the method comprising the following steps:

[0031] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0032] Step 2: Add acrylamide (AM), gelatin (Gel) and tannic acid (TA) powders to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0033] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0034] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution prepared in step 3 and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place it in an oven at 60°C for 4 hours to obtain a strong, antifreeze and highly conductive hydrogel.

[0035] In step 1, the concentration of nanocellulose is 5 wt % and the concentration of dimethyl sulfoxide is 35 wt %.

[0036] In step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 5 wt % of acrylamide, and the concentration of tannic acid is 10 wt % of acrylamide.

[0037] In step three, the concentration of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) is 2 wt % and the dosage is 500 ul.

[0038] In step 4, the amounts of N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) used are 0.1% and 1% of the mass of acrylamide.

[0039] Example 2:

[0040] The present embodiment provides a method for preparing a tough, freeze-resistant and highly conductive composite hydrogel electrode, the method comprising the following steps:

[0041] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0042] Step 2: Add acrylamide (AM), gelatin (Gel) and tannic acid (TA) powders to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0043] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0044] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place it in an oven at 60°C for 4 hours to obtain a strong, antifreeze and highly conductive hydrogel.

[0045] The concentration of nanocellulose in step 1 is 5 wt % and the concentration of dimethyl sulfoxide is 35 wt %.

[0046] In step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 10 wt % of acrylamide, and the concentration of tannic acid is 10 wt % of acrylamide.

[0047] The concentration of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) in step three is 2 wt %, and the amount used is 500 ul.

[0048] The amounts of N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) used in step 4 are 0.1% and 1% of the mass of acrylamide.

[0049] Example 3:

[0050] The present embodiment provides a method for preparing a tough, freeze-resistant and highly conductive composite hydrogel electrode, the method comprising the following steps:

[0051] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0052] Step 2: Add acrylamide (AM), gelatin (Gel) and tannic acid (TA) powders to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0053] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0054] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution prepared in step 3 and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place it in an oven at 60°C for 4 hours to obtain a strong, antifreeze and highly conductive hydrogel.

[0055] In step 1, the concentration of nanocellulose is 5 wt %, and the concentration of dimethyl sulfoxide is 35 wt %.

[0056] In step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 15 wt % of acrylamide, and the concentration of tannic acid is 10 wt % of acrylamide.

[0057] The concentration of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) in step three is 2 wt %, and the amount used is 500 ul.

[0058] The amounts of N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) used in step 4 are 0.1% and 1% of the mass of acrylamide.

[0059] Example 4:

[0060] The present embodiment provides a method for preparing a tough, freeze-resistant and highly conductive composite hydrogel electrode, the method comprising the following steps:

[0061] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0062] Step 2: Add acrylamide (AM), gelatin (Gel) and tannic acid (TA) powders to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0063] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0064] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place it in an oven at 60°C for 4 hours to obtain a strong, antifreeze and highly conductive hydrogel.

[0065] The concentration of nanocellulose in step 1 is 5 wt %, and the concentration of dimethyl sulfoxide is 35 wt %.

[0066] In step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 20 wt % of acrylamide, and the concentration of tannic acid is 10 wt % of acrylamide.

[0067] The concentration of poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) in step three is 2 wt %, and the amount used is 500 ul.

[0068] The amounts of N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) used in step 4 are 0.1% and 1% of the mass of acrylamide.

[0069] Comparative Example 1:

[0070] The difference between this comparative example and the above embodiment is that: in step 1, no dimethyl sulfoxide (DMSO) is added, that is, the mass of DMSO is 0, and the concentration of tannic acid is 10wt% of the acrylamide; in step 2, the concentration of acrylamide is 30wt%, and the concentration of gelatin is 15wt% of the acrylamide; in step 3, the concentration of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) is 2wt%, and the amount used is 500ul; in step 4, the amounts of N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) used are 0.1% and 1% of the mass of acrylamide respectively.

[0071] The specific preparation method comprises the following steps:

[0072] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution;

[0073] Step 2: Add acrylamide (AM), gelatin (Gel) and tannic acid (TA) powders to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0074] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0075] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place it in an oven at 60°C for 4 hours to prepare a hydrogel.

[0076] Comparative Example 2:

[0077] This comparative example differs from the above embodiment in that, in step 1, the concentration of nanocellulose is 5 wt %, the concentration of dimethyl sulfoxide is 35 wt %; in step 2, the concentration of acrylamide is 30 wt %, the concentration of gelatin is 15 wt % of the acrylamide, and no tannic acid (TA) is added, i.e., the mass of TA is 0; in step 3, the concentration of poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) (PEDOT:PSS) is 2 wt %, and the amount used is 500 μl; and in step 4, the amounts of N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) are 0.1% and 1% of the mass of acrylamide, respectively.

[0078] The specific preparation method comprises the following steps:

[0079] Step 1: Add nanocellulose (CNF) to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and then add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent;

[0080] Step 2: Add acrylamide (AM) and gelatin (Gel) powder to the solution prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution;

[0081] Step 3: adding the poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid) solution (PEDOT:PSS) to the solution prepared in step 2, and rapidly stirring for 5 minutes to obtain a mixed solution;

[0082] Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution prepared in step 3 and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place the solution in an oven at 60°C for 4 hours to prepare a hydrogel.

[0083] Test method:

[0084] The mechanical properties, adhesion properties and conductive properties of the conductive hydrogel materials prepared in the examples and comparative examples were tested.

[0085] The specific test method for tensile properties test is as follows:

[0086] The mechanical properties of the hydrogel samples were evaluated using a universal testing machine. Tensile tests were performed on dumbbell-shaped samples measuring 20 × 10 × 2 mm at a constant speed of 100 mm / min. Each experiment was repeated five times, and the average results were recorded.

[0087] The specific test method for compression performance test is as follows:

[0088] The compression test was conducted on a cylindrical sample with a diameter of 10 mm and a height of 10 mm at a constant speed of 10 mm / min. Each experiment was repeated five times and the average result was recorded.

[0089] The specific test method of adhesion performance test is as follows: Using a universal electronic testing machine, the lap shear test is used to calculate the adhesion ability of the hydrogel. The size is 10×10×2mm 3 The hydrogel pattern is fitted onto two pieces of 20×40×3mm 3 The substrates were pressed with a 500 g weight for 1 minute to ensure close contact.

[0090] Next, a tensile test was performed at a constant speed of 10 mm / min to obtain the adhesion strength of the sample.

[0091] The specific testing method for sensing performance is as follows: Different stretch lengths are set on a universal testing machine connected to a digital source instrument to test the strain sensitivity of the hydrogel sensor under different tensile strains. Flexible sensors are attached to different moving joints of the human body, such as the fingers, elbows, and knees, to monitor different movements. Real-time resistance changes under different motion states are recorded in real time via a computer control interface, and the results are analyzed and calculated. Electrodes are then attached to the arm muscles and wrist to record muscle electrical activity and electrocardiogram (ECG).

[0092] The test results are shown in the table below.

[0093]

[0094] As can be seen from the accompanying drawings, the hydrogel prepared by the present invention is a strong and highly conductive composite hydrogel, which can be used as a strain sensor for sensing monitoring.

[0095] Therefore, the method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode provided by the present invention has a product with better working ability than the prior art, and can greatly shorten the preparation steps and improve work efficiency.

Claims

1. A method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode, characterized by: The method includes the following steps: Step 1: Add nanocellulose to deionized water, stir rapidly, and disperse it using an ultrasonic device to obtain a uniform dispersed solution, and add dimethyl sulfoxide (DMSO) to the dispersed solution to obtain a mixed binary solvent; Step 2: Add acrylamide AM, gelatin Gel and tannic acid TA powder to the binary solvent prepared in step 1, and stir at room temperature to dissolve them to obtain a uniform and clear precursor solution; Step 3: adding the poly (3,4-ethylenedioxythiophene): polystyrenesulfonic acid PEDOT: PSS solution to the precursor solution prepared in step 2, and rapidly stirring to obtain a mixed solution; Step 4: Add N,N'-methylenebisacrylamide (MBA) and ammonium persulfate (APS) to the mixed solution prepared in step 3 and stir for 15 minutes to obtain a hydrogel precursor solution. After stirring evenly and ultrasonically defoaming, place the solution in an oven at 60°C for 4 hours to obtain a strong, frost-resistant and highly conductive hydrogel.

2. The method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode according to claim 1, characterized in that: The concentration of nanocellulose in step 1 is 5 wt %, and the concentration of dimethyl sulfoxide is 35 wt %.

3. The method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode according to claim 1, characterized in that: The concentration of acrylamide in step 2 is 30wt%, the concentration of gelatin is 5-20wt% of acrylamide, and the concentration of tannic acid is 10wt% of acrylamide.

4. The method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode according to claim 1, characterized in that: The concentration of the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate PEDOT:PSS solution in step 3 is 2 wt %.

5. The method for preparing a tough, frost-resistant and highly conductive composite hydrogel electrode according to claim 1, characterized in that: The amounts of N,N'-methylenebisacrylamide MBA and ammonium persulfate APS in step 4 are 0.1% and 1% of the mass of acrylamide.

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