Preparation method of polyvinyl alcohol-based hydrogel doped with carbon quantum dots and application thereof
By preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots, the problem of unstable electrical signals in hydrogel materials after carbon quantum doping was solved, achieving improvements in both mechanical properties and electrical signals. It also possesses environmentally friendly degradation capabilities and is suitable for flexible sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LULIANG UNIV
- Filing Date
- 2026-03-17
- Publication Date
- 2026-06-09
AI Technical Summary
Existing hydrogel materials, after being doped with carbon quantum dots, are difficult to achieve effective synergy, resulting in unstable electrical signals and difficulty in balancing mechanical properties and dielectric constant.
Carbon quantum dot liquid was prepared by hydrothermal method by mixing polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde and glycerol with carbon quantum dot ethanol solution in a specific ratio to form a polyvinyl alcohol-based hydrogel doped with carbon quantum dots, which was then applied to flexible sensors.
It improves the mechanical and electrical signal transmission properties of hydrogels, has excellent tensile and torsional properties, adapts to the complex curves of the human body, and has environmental degradation capabilities.
Smart Images
Figure CN121895597B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of hydrogel technology, and in particular to a method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots and their applications. Background Technology
[0002] Hydrogels are flexible materials with a semi-solid and liquid structure, which gives them many unique properties. Unlike ordinary solid materials, hydrogels can absorb large amounts of water, forming a hydrogel-like substance. When exposed to external stimuli such as temperature, electric fields, light, and pressure, the structure of hydrogels changes, leading to changes in their properties; this response is known as "smart response." Therefore, hydrogel materials are widely used in the field of sensors.
[0003] Carbon dots (CDs) have attracted much attention as a novel type of carbon nanomaterial due to their excellent charge transfer capabilities and fluorescence properties resulting from quantum confinement and edge effects. These materials are characterized by lateral dimensions of less than 10 nanometers, excellent dispersibility, and a variety of functional groups distributed on their surface, including carboxyl groups (-COOH), carbonyl groups (-C=O), hydroxyl groups (-OH), and hydrocarbon chains with different degrees of polymerization.
[0004] Given the instability of electrical signals in hydrogels, when carbon quantum dots are uniformly incorporated into the polymer matrix to form rich interfacial structures in the composite material, thereby promoting multiple interfacial polarization effects, it is difficult to achieve effective synergy. Balancing dielectric constant, mechanical properties, and improving electrical signal stability presents technical challenges and requires further improvement. Summary of the Invention
[0005] In view of this, the first objective of this application is to provide a method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots, so as to improve mechanical properties, electrical signal transmission performance, and environmental friendliness. The specific solution is as follows:
[0006] A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots includes the following steps:
[0007] Step 1, Material Preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use;
[0008] Step 2, Initial mixing: Mix and stir the polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, then add glutaraldehyde and glycerol, and stir to obtain a creamy mixed solution;
[0009] Step 3, Final Mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and leave it at room temperature to obtain a hydrogel;
[0010] The volume ratio of polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde and glycerol in the creamy mixed solution is 10:5-5.2:0.055-0.057:0.087-0.089, and the volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel is 5:1.95-2.05.
[0011] Preferably, the carbon quantum dot ethanol solution is prepared by hydrothermal method using coffee grounds as a precursor to obtain carbon quantum dot liquid, and then the carbon quantum dot liquid is mixed with anhydrous ethanol at a volume ratio of 1.2:0.8 to obtain the solution.
[0012] Preferably, in step 1, the preparation of the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution is carried out by using a magnetic stirrer and controlling the temperature at 78-80℃ for 100-105 min.
[0013] Preferably, in step 2, the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution are mixed and stirred with a glass rod for 9-12 minutes.
[0014] Preferably, in step 3, the room temperature placement is controlled for a placement time of 46-50 hours.
[0015] The second objective of this application is to provide an application of a carbon quantum doped polyvinyl alcohol-based hydrogel, including a carbon quantum doped polyvinyl alcohol-based hydrogel prepared by the method described above, and its application in a flexible sensor.
[0016] Preferably, the flexible sensor is prepared by the following steps:
[0017] Step 1: Set up the sensor model;
[0018] Step 2: Perform voltage / current tests on the sensor model under strain / pressure to obtain the linear response relationship;
[0019] Step 3: Fix the sensor model to each joint of the human body to collect the corresponding voltage signals;
[0020] Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
[0021] Preferably, in step 3, the voltage signal includes voltage signals collected from the sensor output at different angles, and the voltage signals output by the sensor exhibit significant amplitude differences and change periodically with the action.
[0022] As shown above, this application provides a method for preparing carbon quantum dot-doped polyvinyl alcohol (PVA) hydrogels and their applications. The PVA hydrogels prepared by this method exhibit excellent tensile and torsional mechanical properties, allowing them to conform to the complex curves of the human body. Furthermore, the carbon quantum dots increase surface defects, thereby improving the dielectric constant and mechanical properties. The PVA hydrogels also possess the ability to degrade naturally in the environment, thus achieving environmental protection. The application of these carbon quantum dot-doped PVA hydrogels offers advantages in improving mechanical properties, electrical signal transmission performance, and environmental friendliness. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0024] Figure 1 This is a scanning electron microscope (TEM) image of the carbon quantum dot ethanol solution disclosed in Example 1 of this application;
[0025] Figure 2 This is the fluorescence spectrum of the carbon quantum dot ethanol solution disclosed in Example 1 of this application;
[0026] Figure 3 This is a diagram showing the effect of the carbon quantum doped polyvinyl alcohol-based hydrogel disclosed in Embodiment 1 of this application under ultraviolet light.
[0027] Figure 4 The Fourier transform infrared spectrum of the polyvinyl alcohol-based hydrogel doped with carbon quantum dots disclosed in Embodiment 1 of this application;
[0028] Figure 5 The tensile test results of the carbon quantum doped polyvinyl alcohol-based hydrogel disclosed in Embodiment 1 of this application are shown in (a1), (a2) and (b).
[0029] Figure 6 This is a degradation test result image of the carbon quantum doped polyvinyl alcohol-based hydrogel disclosed in Embodiment 1 of this application;
[0030] Figure 7 This is a graph showing the voltage response of the hydrogel electrode with the first carbon dot addition amount of the flexible sensor disclosed in Embodiment 1 of this application.
[0031] Figure 8 This is a graph showing the current response of the hydrogel electrode with the second carbon dot addition amount of the flexible sensor disclosed in Embodiment 1 of this application.
[0032] Figure 9 This is a cyclic test signal diagram of the flexible sensor disclosed in Embodiment 1 of this application;
[0033] Figure 10 This is a detailed waveform diagram of the cyclic test signal of the flexible sensor disclosed in Embodiment 1 of this application;
[0034] Figure 11 This is a diagram showing the voltage signals collected by each joint of the flexible sensor disclosed in Embodiment 1 of this application. Detailed Implementation
[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0036] It should be mentioned that the carbon quantum dot ethanol solution in this embodiment is prepared by using coffee grounds as a precursor and obtaining carbon quantum dot liquid via a hydrothermal method. The carbon quantum dot liquid is then mixed with anhydrous ethanol at a volume ratio of 1.2:0.8. Of course, the volume ratio of carbon quantum dot liquid to anhydrous ethanol can also be any ratio such as 1:0.8, 1.1:0.8, or 1.3:0.8.
[0037] like Figure 1 The TEM image shown, based on a 50nm scale, reveals that the carbon quantum dot liquid particles are dispersed nanoscale dots, concentrated in the 1-6nm range, with a spherical morphology and no obvious aggregation. Figure 2 As shown in the fluorescence spectrum of the carbon quantum dot ethanol solution, the high-intensity region is concentrated within the excitation wavelength range of 400-500 nm and the emission wavelength range of 450-550 nm, forming a distinct elliptical high-intensity region. This indicates that the fluorescent material has a wide excitation / emission wavelength range, consistent with the fluorescence characteristic of carbon quantum dots without a single fixed wavelength. The highest fluorescence intensity is observed at an excitation wavelength of approximately 450 nm and an emission wavelength of approximately 500 nm, indicating that the material exhibits the strongest fluorescence emission under these excitation conditions, displaying blue fluorescence. Therefore, this material is coffee grounds carbon quantum dots, and its fluorescence color is blue.
[0038] The following will provide a detailed description of a method for preparing a carbon quantum doped polyvinyl alcohol-based hydrogel and its application.
[0039] A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots includes the following steps:
[0040] Step 1, Material preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use. In the preparation of polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, use a magnetic stirrer and control the temperature at 78-80℃ to stir for 100-105 min.
[0041] Step 2, Initial mixing: Mix the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution with stirring. Control the mixing and stirring of the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution to be 9-12 minutes with a glass rod. Then add glutaraldehyde and glycerol and stir to obtain a creamy mixed solution.
[0042] Step 3, final mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and let it stand at room temperature for 46-50 hours to obtain a hydrogel;
[0043] The volume ratio of the creamy mixed solution to the polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde, and glycerol is 10:5-5.2:0.055-0.057:0.087-0.089. The volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel is 5:1.95-2.05.
[0044] An application of a carbon quantum dot-based polyvinyl alcohol hydrogel includes preparing a carbon quantum dot-based polyvinyl alcohol hydrogel using the carbon quantum dot-based polyvinyl alcohol hydrogel preparation method described above, and applying it to a flexible sensor.
[0045] Preferably, the flexible sensor is prepared by the following steps:
[0046] Step 1: Set up the sensor model;
[0047] Step 2: Perform voltage / current tests on the sensor model under strain / pressure to obtain the linear response relationship;
[0048] Step 3: Fix the sensor model to each joint of the human body to collect corresponding voltage signals. The voltage signals include the voltage signals output by the sensor at different angles, and the voltage signals output by the sensor show obvious amplitude differences and the signals change periodically with the movement.
[0049] Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
[0050] Example 1
[0051] A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots includes the following steps:
[0052] Step 1, Material preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use. In the preparation of polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, use a magnetic stirrer and control the temperature at 78℃ for 103 min.
[0053] Step 2, Initial mixing: Mix the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution with stirring. Control the mixing and stirring of the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution to be stirred with a glass rod for 9 minutes. Then add glutaraldehyde and glycerol, and stir to obtain a creamy mixed solution.
[0054] Step 3, final mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and let it stand at room temperature for 46 hours to obtain a hydrogel;
[0055] The volume ratio of the creamy mixed solution to the polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde, and glycerol was 10:5.1:0.055:0.087. The volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel was 5:1.95.
[0056] An application of a carbon quantum dot-based polyvinyl alcohol hydrogel includes preparing a carbon quantum dot-based polyvinyl alcohol hydrogel using the carbon quantum dot-based polyvinyl alcohol hydrogel preparation method described above, and applying it to a flexible sensor.
[0057] Preferably, the flexible sensor is prepared by the following steps:
[0058] Step 1: Set up the sensor model;
[0059] Step 2: Perform voltage / current tests on the sensor model under strain / pressure to obtain the linear response relationship;
[0060] Step 3: Fix the sensor model to each joint of the human body to collect corresponding voltage signals. The voltage signals include the voltage signals output by the sensor at different angles, and the voltage signals output by the sensor show obvious amplitude differences and the signals change periodically with the movement.
[0061] Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
[0062] Example 2
[0063] A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots includes the following steps:
[0064] Step 1, Material preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use. In the preparation of polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, use a magnetic stirrer and control the temperature at 79℃ for 105 min.
[0065] Step 2, Initial mixing: Mix the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution with stirring. Control the mixing and stirring of the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution to be stirred with a glass rod for 12 minutes. Then add glutaraldehyde and glycerol and stir to obtain a creamy mixed solution.
[0066] Step 3, final mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and let it stand at room temperature for 50 hours to obtain a hydrogel;
[0067] The volume ratio of the creamy mixed solution to the polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde, and glycerol was 10:5.2:0.057:0.089. The volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel was 5:2.05.
[0068] An application of a carbon quantum dot-based polyvinyl alcohol hydrogel includes preparing a carbon quantum dot-based polyvinyl alcohol hydrogel using the carbon quantum dot-based polyvinyl alcohol hydrogel preparation method described above, and applying it to a flexible sensor.
[0069] Preferably, the flexible sensor is prepared by the following steps:
[0070] Step 1: Set up the sensor model;
[0071] Step 2: Perform voltage / current tests on the sensor model under strain / pressure to obtain the linear response relationship;
[0072] Step 3: Fix the sensor model to each joint of the human body to collect corresponding voltage signals. The voltage signals include the voltage signals output by the sensor at different angles, and the voltage signals output by the sensor show obvious amplitude differences and the signals change periodically with the movement.
[0073] Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
[0074] Example 3
[0075] A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots includes the following steps:
[0076] Step 1, Material preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use. In the preparation of polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, use a magnetic stirrer and control the temperature at 80℃ for 100 min.
[0077] Step 2, Initial mixing: Mix and stir the polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution. Control the mixing and stirring of the polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution to stir with a glass rod for 10 minutes. Then add glutaraldehyde and glycerol, and stir to obtain a creamy mixed solution.
[0078] Step 3, final mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and let it stand at room temperature for 48 hours to obtain a hydrogel;
[0079] The volume ratio of the creamy mixed solution to the polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde, and glycerol was 10:5:0.056:0.088. The volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel was 5:2.
[0080] An application of a carbon quantum dot-based polyvinyl alcohol hydrogel includes preparing a carbon quantum dot-based polyvinyl alcohol hydrogel using the carbon quantum dot-based polyvinyl alcohol hydrogel preparation method described above, and applying it to a flexible sensor.
[0081] Preferably, the flexible sensor is prepared by the following steps:
[0082] Step 1: Set up the sensor model;
[0083] Step 2: Perform voltage / current tests on the sensor model under strain / pressure to obtain the linear response relationship;
[0084] Step 3: Fix the sensor model to each joint of the human body to collect corresponding voltage signals. The voltage signals include the voltage signals output by the sensor at different angles, and the voltage signals output by the sensor show obvious amplitude differences and the signals change periodically with the movement.
[0085] Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
[0086] Performance testing was conducted based on Example 3, such as... Figure 3 As shown in the image, the polyvinyl alcohol-based hydrogel doped with carbon quantum dots prepared in Example 3 exhibits blue fluorescence under ultraviolet light, demonstrating that the polyvinyl alcohol-based hydrogel doped with carbon quantum dots prepared in Example 3 displays uniform blue fluorescence. Figure 4As shown, the hydrogel of the undoped carbon quantum dot ethanol solution was used as a control group and compared with that of Example 3. The carbon quantum dot liquid, the polyvinyl alcohol-based hydrogel doped with carbon quantum dots prepared in Example 3, and the control group were arranged from top to bottom at a depth of 3400 cm. -1 1600 cm -1 1050cm -1 The peaks at these locations represent the stretching vibrations of OH, C=C, and CO, respectively. The carbon quantum dot liquid is derived from the carbonization of coffee grounds and has abundant oxygen-containing functional groups on its surface. The control group showed peaks at 3400 cm⁻¹. -1 1600 cm -1 1050cm -1 The peaks at these locations represent the stretching vibrations of OH, C=C, and CO, respectively. The polyvinyl alcohol-based hydrogel doped with carbon quantum dots prepared in Example 3 of this application retains the stretching vibration peaks present in the control group while also exhibiting the stretching vibration peaks of the carbon quantum dot liquid. Its peak shape is more complex than that of the control group, demonstrating that the carbon quantum dots in the carbon quantum dot liquid are fully doped.
[0087] Mechanical performance tests were conducted based on the embodiments, such as Figure 5 As shown in (a1) and (a2), during the test, a hydrogel with dimensions of 10mm × 6mm × 1mm was fixed in a clamp and tested on a hand-cranked tensile testing machine. According to the formula: elongation = (L - L0) / L0 × 100%, the elongation of the carbon quantum doped polyvinyl alcohol-based hydrogel prepared in Example 3 reached 700%. As can be seen from the video, it detached from the clamp at the end of the test, rather than tearing, so the elongation may be even higher. Furthermore, the carbon quantum doped polyvinyl alcohol-based hydrogel prepared in Example 3 can support a 100g weight and withstand various deformations such as torsion and curling, demonstrating its excellent mechanical properties and adaptability to various deformations.
[0088] When testing the maximum tensile force, a hydrogel measuring 20 mm long × 6 mm wide × 1 mm thick was selected and fixed at both ends with clamps. Figure 5 As shown in (b), the test was conducted on a hand-cranked tensile testing machine. The tensile strength can be obtained from the maximum tensile force obtained during the test. The formula for calculating tensile strength is: Tensile Strength = Maximum Bearing Force / Cross-sectional Area Under Force.
[0089] 1. Calculate the cross-sectional area of the membrane under stress.
[0090]
[0091] 2. Tensile strength
[0092]
[0093] Hydrophilicity tests were conducted based on Example 3. A 5ml syringe filled with water was placed a short distance above the hydrogel, and a drop of water was dropped onto the surface of the hydrogel. The changes of the water droplet on the hydrogel surface were observed over three seconds. The tests revealed that the contact angle of the carbon quantum doped polyvinyl alcohol-based hydrogel prepared in Example 3 was 79.2° in the first second, 67.6° in the second second, and 50.4° in the third second. Furthermore, the contact angle gradually decreased with increasing contact time, and all contact angles were less than 90°, indicating strong hydrophilicity.
[0094] Based on the environmental performance test conducted in Example 3, 2×2cm [materials] were added to a 50ml glass beaker containing 30ml of tap water. 2 The turbidity of the polyvinyl alcohol-based hydrogel doped with carbon quantum dots prepared in Example 3 was tested every 20 minutes, as shown in the figure. Figure 6 As shown, its turbidity increases over time and eventually tends to stabilize. This indicates that the polyvinyl alcohol-based hydrogel with carbon quantum dots prepared in Example 3 is decomposed into small molecules in water, resulting in an increase in turbidity. After the decomposition is completed, the turbidity tends to stabilize, indicating that it has the effect of being degraded in tap water and has high environmental friendliness.
[0095] Based on Example 3, antibacterial performance was tested. Cultured Staphylococcus aureus was inoculated onto two petri dishes. A 1cm radius polyvinyl alcohol hydrogel doped with carbon quantum dots, prepared in Example 3, and filter paper were placed in the center of each dish. Observation revealed that no inhibition zone was observed in the petri dish with filter paper, and bacterial growth and reproduction on and around the sample surface were normal, showing no difference from other areas. However, a clear inhibition zone was observed around the polyvinyl alcohol hydrogel doped with carbon quantum dots prepared in Example 3. This demonstrates that the polyvinyl alcohol hydrogel doped with carbon quantum dots prepared in Example 3 of this application possesses antibacterial properties and can maintain inhibition of bacterial growth for a relatively long period.
[0096] like Figure 7 , Figure 8 As shown, the voltage and current response graphs of hydrogel electrodes with different carbon dot addition amounts under the same stress condition are displayed. The hydrogel obtained by mixing liquid carbon dots with anhydrous ethanol at a doping volume ratio of 1.2:0.8 exhibits the highest response voltage and current intensity. Therefore, the carbon quantum dot ethanol solutions in the embodiments of this application all use the above-mentioned volume ratio of liquid carbon dots mixed with anhydrous ethanol.
[0097] like Figure 9 As shown, the cyclic test signal graph based on the flexible sensor reveals that the signal changes over time, but the overall trend is stable and periodic. Figure 10As shown, the detailed waveform of the signal can be seen, with peaks and troughs alternating. The intervals between peaks are approximately 1 second, 2.108 seconds, and 3.108 seconds, and two adjacent points are located at adjacent peak positions to prove its periodicity.
[0098] like Figure 11 As shown in the diagram, the voltage signals collected from each joint of the flexible sensor reveal two key characteristics: First, the waveform exhibits regular, periodic changes. Second, during specific stretching movements, corresponding physiological parameters change in various key parts of the human body. Based on... Figure 11 The data in the sensor can be used to assess the standardization of movements, the degree of muscle activation, and the range of motion of joints, making it suitable for use as a sensor in a wide range of applications, such as motion detection.
[0099] In summary, this application provides a method for preparing carbon quantum dot-doped polyvinyl alcohol (PVA) hydrogels and their applications. The PVA hydrogels prepared by this method exhibit excellent tensile and torsional mechanical properties, allowing them to conform to the complex curves of the human body. Furthermore, the carbon quantum dots increase surface defects, thereby improving the dielectric constant and mechanical properties. The PVA hydrogels also possess the ability to degrade naturally in the environment, thus achieving environmental protection goals. The application of these carbon quantum dot-doped PVA hydrogels offers advantages in improving mechanical properties, electrical signal transmission performance, and environmental friendliness.
[0100] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.
[0101] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0102] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method for preparing a polyvinyl alcohol-based hydrogel doped with carbon quantum dots, characterized in that, Includes the following steps: Step 1, Material Preparation: Prepare 10% polyvinyl alcohol aqueous solution, 10% polyvinyl alcohol dimethyl sulfoxide solution and carbon quantum dot ethanol solution for later use; Step 2, Initial Mixing: Mix and stir the polyvinyl alcohol aqueous solution and polyvinyl alcohol dimethyl sulfoxide solution, then add glutaraldehyde and glycerol, and stir to obtain a creamy mixed solution; Step 3, Final Mixing: Add carbon quantum dot ethanol solution to the creamy mixture, stir to obtain a brown transparent liquid, place it in a mold and leave it at room temperature to obtain a hydrogel; The volume ratio of polyvinyl alcohol aqueous solution, polyvinyl alcohol dimethyl sulfoxide solution, glutaraldehyde and glycerol in the creamy mixed solution is 10:5-5.2:0.055-0.057:0.087-0.089, and the volume ratio of the creamy mixed solution to the carbon quantum dot ethanol solution in the hydrogel is 5:1.95-2.
05. The carbon quantum dot ethanol solution is prepared by hydrothermal method using coffee grounds as a precursor to obtain carbon quantum dot liquid, and then the carbon quantum dot liquid is mixed with anhydrous ethanol at a volume ratio of 1.2:0.8 to obtain the solution.
2. The method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots according to claim 1, characterized in that: In step 1, the preparation of the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution is carried out by using a magnetic stirrer and controlling the temperature at 78-80℃ for 100-105 min.
3. The method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots according to claim 1, characterized in that: In step 2, the polyvinyl alcohol aqueous solution and the polyvinyl alcohol dimethyl sulfoxide solution are mixed and stirred with a glass rod for 9-12 minutes.
4. The method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots according to claim 1, characterized in that: In step 3, the room temperature placement is controlled to last for 46-50 hours.
5. An application of a polyvinyl alcohol-based hydrogel doped with carbon quantum dots, characterized in that: This includes polyvinyl alcohol-based hydrogels doped with carbon quantum dots prepared using the method for preparing polyvinyl alcohol-based hydrogels doped with carbon quantum dots as described in any one of claims 1-4, and applied to flexible sensors.
6. The application of the polyvinyl alcohol-based hydrogel doped with carbon quantum dots according to claim 5, characterized in that, The flexible sensor is prepared by the following steps: Step 1: Set up the sensor model; Step 2: Perform voltage test under strain, current test under strain, voltage test under pressure, or current test under pressure on the sensor model to obtain the linear response relationship; Step 3: Fix the sensor model to each joint of the human body to collect the corresponding voltage signals; Step 4: Fix conductive fabric to the hydrogel side of the sensor model and seal it with a silicone mold.
7. The application of the polyvinyl alcohol-based hydrogel doped with carbon quantum dots according to claim 6, characterized in that: In step 3, the voltage signal includes voltage signals collected from the sensor output at different angles, and the voltage signals output by the sensor exhibit amplitude differences and change periodically with the action.