Intelligent humidity regulation and control flexible electrode and preparation method thereof
By using a thermosensitive polymer porous material layer of high and low critical dissolution temperature in the electronic skin, combined with the conductive material layer, the reversible change of the electrode wetting gradient is achieved, which solves the problem of insufficient breathability and moisture permeability during long-term wear of existing electronic skins, and realizes intelligent humidity regulation and wear comfort improvement under different weather conditions.
Patent Information
- Application Number
- CN202311436816.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-31
- Publication Date
- 2025-05-02
AI Technical Summary
The existing electronic skin is not breathable and moisture-permeable when worn for a long time, resulting in signal attenuation, offset and sensor failure, and it is difficult to adapt to changes in the hot and cold environment, affecting the wearing comfort.
A porous material layer loaded with a temperature-sensitive polymer with a high critical dissolution temperature and a low critical dissolution temperature is used, and combined with a conductive material layer, a reversible transformation of the electrode wettability gradient is achieved. The polymer is hydrophobic at low temperatures and hydrophilic at high temperatures, achieving intelligent humidity regulation.
It can dissipate heat and moisture in hot weather, and in cold weather, improve wear comfort, and adapt to changes in complex environments.
Smart Images
Figure CN119920525A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electrode technology, and in particular relates to an intelligent humidity control flexible electrode and a preparation method thereof. Background Art
[0002] Due to its unique properties, such as thinness, lightness, good biocompatibility, excellent mechanical stability and skin conformality, electronic skin can collect important physiological signals of the human body in real time and continuously in a non-invasive and imperceptible way, providing a strong basis for health status analysis and opening up a convenient and non-invasive way for disease prediction, prevention, diagnosis and treatment.
[0003] Existing electronic skins are mainly based on plastics, elastomers and hydrogels. Due to their insufficient air permeability and moisture permeability, long-term wearing will accumulate sweat between the device and the skin, causing signal attenuation, offset and sensor failure, causing discomfort to the user, and in severe cases, inflammation. Although there are reports that the air permeability of electronic skins can be improved by introducing porous structures to keep them comfortable to wear in hot and humid environments, these porous electronic skins are not conducive to keeping the human body warm and moist in cold environments. In addition, the actual application environment of electronic skins can also be complex, often involving transitions between hot and cold environments. When the surrounding environment changes suddenly, the huge temperature difference between the human body and the environment usually causes severe discomfort and even a series of diseases. Summary of the invention
[0004] The purpose of the present invention is to provide an intelligent humidity-regulating flexible electrode, so as to obtain an intelligent electronic skin that can dissipate heat and moisture in hot weather and keep warm and moist in cold weather.
[0005] To solve the above technical problems, the first aspect of the present invention provides an intelligent humidity-regulating flexible electrode, comprising: a porous material layer loaded with a polymer having a high critical solution temperature, a porous material layer loaded with a polymer having a low critical solution temperature, and a conductive material layer.
[0006] Compared with the prior art, the intelligent humidity control flexible electrode provided by the present invention innovatively uses two thermosensitive polymers. The structure or solubility of the thermosensitive polymer itself will change with the change of temperature. The temperature at which the polymer structure or solubility changes is called the transition temperature. Since the solubility changes at this temperature point, it is also called the critical solution temperature. Thermosensitive polymers are divided into two categories: one is a polymer with a low critical solution temperature (lower critical solution temperature, LCST), that is, a LCST-type polymer. When the temperature is lower than its LCST, the polymer dissolves in the solution and is homogeneous, and when it is higher than the LCST, the polymer undergoes phase separation; therefore, the polymer with a low critical solution temperature is hydrophilic at low temperatures and hydrophobic at high temperatures. The other type is a polymer with a high critical solution temperature (uppercritical solution temperature, UCST), that is, a UCST-type polymer. When the temperature is higher than its UCST, the polymer is completely dissolved and homogeneous. Therefore, the polymer with the highest critical solution temperature is hydrophobic at low temperatures and hydrophilic at high temperatures. In the present invention, under the action of two polymers with opposite temperature response properties, the electrode wettability gradient undergoes a reversible change as the temperature changes. In practical applications, the polymer side with the lowest critical solution temperature faces the skin (inside). At low temperatures, sweat cannot be transferred from the hydrophilic side (inside) to the hydrophobic side (outside), achieving the effect of moisturizing and heat preservation; at high temperatures, sweat is transferred from the hydrophobic side (inside) to the hydrophilic side (outside), achieving the effect of heat dissipation and moisture permeability, and realizing intelligent humidity control. Therefore, the temperature adaptability of the electrode greatly improves the wearing comfort, and a smart electronic skin can be obtained that dissipates heat and moisture in hot weather and keeps warm and moist in cold weather.
[0007] Optionally, in the intelligent humidity-controlling flexible electrode provided by the present invention, the porous material in the porous material layer is selected from any one of cellulose acetate membrane, cellulose membrane, cotton cloth, polyacrylonitrile or silk.
[0008] Optionally, in the intelligent humidity-regulating flexible electrode provided by the present invention, the polymer with a high critical solution temperature is selected from any one of poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide], poly(acryloyl asparagine), poly(acrylonitrile-co-acrylamide) or poly(N-isopropylacrylamide)-b-poly[3-(N-(3-methacrylamidepropyl)N,N-dimethyl)aminopropane sulfonate].
[0009] Optionally, in the intelligent humidity-regulating flexible electrode provided by the present invention, the polymer with a low critical solution temperature is selected from any one of poly[2-(2-methoxyethoxy)ethoxymethacrylate], poly(N-isopropylacrylamide), poly(methyl vinyl ether) or polydimethylaminoethyl methacrylate.
[0010] Optionally, in the intelligent humidity-controlling flexible electrode provided by the present invention, the conductive material is selected from any one of metal nanomaterials, carbon materials or conductive polymers.
[0011] Optionally, in the intelligent humidity-regulating flexible electrode provided by the present invention, the metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets.
[0012] Optionally, in the intelligent humidity control flexible electrode provided by the present invention, the carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials.
[0013] Optionally, in the intelligent humidity-regulating flexible electrode provided by the present invention, the conductive polymer is selected from any one of polypyrrole, polyaniline, and PEDOT:PSS materials.
[0014] Optionally, in the intelligent humidity-control flexible electrode provided by the present invention, the thickness of the porous material layer loaded with a polymer having a high critical solution temperature is 5 μm to 100 μm, the thickness of the porous material layer loaded with a polymer having a low critical solution temperature is 30 μm to 500 μm; the thickness of the conductive material layer is 100 nm to 500 μm.
[0015] Preferably, in the intelligent humidity control flexible electrode provided by the present invention, the polymer with a high critical solution temperature is poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide] (PDMAPS), and the polymer with a low critical solution temperature is poly(N-isopropylacrylamide) (PNIPAM). The transition temperatures of these two thermosensitive polymers are similar, so when the temperature approaches the critical temperature, the wettability gradient changes at the same time, realizing a reversible wettability gradient that changes with temperature, which can be used to prepare electronic skin with reversible unidirectional water transport with temperature response.
[0016] The second aspect of the present invention provides a method for preparing the intelligent humidity-controlling flexible electrode described in the first aspect, which comprises the following steps in sequence: S1: using any one of thermally initiated free radical polymerization or photo-initiated free radical polymerization to introduce a polymer with a high critical solution temperature into a porous material to obtain a porous material layer loaded with a polymer with a high critical solution temperature; S2: using any one of thermally initiated free radical polymerization or photo-initiated free radical polymerization to introduce a polymer with a low critical solution temperature into a porous material to obtain a porous material layer loaded with a polymer with a low critical solution temperature; S3: bonding the porous material layer loaded with a high critical solution temperature polymer and the porous material layer loaded with a low critical solution temperature polymer together, spraying deionized water from one side of the porous material layer loaded with a low critical solution temperature polymer, drying at room temperature, and bonding the two layers of material together to obtain a composite porous membrane; S4: on the side of the porous material layer loaded with a polymer with a low critical solution temperature of the composite porous membrane, preparing a conductive material layer by any one of magnetron sputtering, vacuum evaporation, electrostatic spraying or impregnation to obtain the intelligent humidity-controlling flexible electrode. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 These are optical pictures of the wettability change detection of the intelligent humidity control flexible electrode in Example 1 at high temperature and low temperature, wherein 1-a shows the wettability of the PNIPAM@CA layer at low temperature; 1-b shows the wettability of the PNIPAM@CA layer at high temperature; 1-c shows the wettability of the PDMAPS@CM layer at low temperature; 1-d shows the wettability of the PDMAPS@CM layer at high temperature;
[0018] Figure 2 It is an optical picture of the change detection of the water transfer performance of the intelligent humidity control flexible electrode at high temperature and low temperature in Example 1, showing the water transfer performance of the intelligent humidity control flexible electrode at high temperature and low temperature in Example 1, wherein 2-a shows the water transfer performance of the intelligent humidity control flexible electrode at high temperature, and 2-b shows the water transfer performance of the intelligent humidity control flexible electrode at low temperature;
[0019] Figure 3 is the water vapor permeation curve of the intelligent humidity control flexible electrode at high temperature and low temperature in Example 1;
[0020] Figure 4 The intelligent humidity control flexible electrode in Example 1 monitors the skin hydration level and temperature changes when the environment changes from low temperature to high temperature, wherein 4-a shows the hydration level change and 4-b shows the temperature change;
[0021] Figure 5It is the change of optical transmittance of the thermosensitive polymer solution loaded by the intelligent humidity-controlled flexible electrode in Example 1 with temperature, wherein 5-a shows the change of optical transmittance of PNIPAM solution with temperature, and 5-b shows the change of optical transmittance of PDMAPSPPNIPAM solution with temperature. DETAILED DESCRIPTION
[0022] In order to more clearly understand the purpose, characteristics and advantages of the present invention, the advantages of the present application are further illustrated in conjunction with specific examples and comparative examples. The materials used without indicating the manufacturer are all conventional products that can be purchased commercially. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.
[0023] Some embodiments of the present invention provide an intelligent humidity-regulating flexible electrode, comprising: a porous material layer loaded with a polymer having a high critical solution temperature, a porous material layer loaded with a polymer having a low critical solution temperature, and a conductive material layer.
[0024] In the embodiment of the present invention, two kinds of thermosensitive polymers are innovatively used. The structure or solubility of the thermosensitive polymer itself will change with the change of temperature. The temperature at which the polymer structure or solubility changes is called the transition temperature. Since the solubility changes at this temperature point, it is also called the critical solution temperature. Thermosensitive polymers are divided into two categories: one is a polymer with a low critical solution temperature (lower critical solution temperature, LCST), i.e., LCST-type polymers. When the temperature is lower than its LCST, the polymer dissolves in the solution and is homogeneous, and when it is higher than the LCST, the polymer undergoes phase separation; therefore, the polymer with a low critical solution temperature is hydrophilic at low temperatures and hydrophobic at high temperatures. Another type is a polymer with a high critical solution temperature (upper critical solution temperature, UCST), i.e., a UCST-type polymer. When the temperature is higher than its UCST, the polymer is completely dissolved and is homogeneous. Therefore, the polymer with the highest critical solution temperature is hydrophobic at low temperatures and hydrophilic at high temperatures. In the present invention, under the action of two polymers with opposite temperature response properties, as the temperature changes, the electrode wettability gradient undergoes a reversible change. In practical applications, the polymer side with the lowest critical solution temperature faces the skin (inside). At low temperatures, sweat cannot be transferred from the hydrophilic side (inside) to the hydrophobic side (outside), achieving the effect of moisturizing and heat preservation; at high temperatures, sweat is transferred from the hydrophobic side (inside) to the hydrophilic side (outside), achieving the effect of heat dissipation and moisture permeability, and realizing intelligent humidity control. Therefore, the temperature adaptability of the electrode greatly improves the wearing comfort, and a smart electronic skin can be obtained that dissipates heat and moisture in hot weather and keeps warm and moist in cold weather.
[0025] In some embodiments of the present invention, the porous material in the porous material layer is selected from any one of cellulose acetate membrane, cellulose membrane, cotton cloth, polyacrylonitrile or silk.
[0026] In some embodiments of the present invention, the polymer having a high critical solution temperature is selected from any one of poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide], poly(acryloyl asparagine), poly(acrylonitrile-co-acrylamide) or poly(N-isopropylacrylamide)-b-poly[3-(N-(3-methacrylamidepropyl)N,N-dimethyl)aminopropane sulfonate].
[0027] In some embodiments of the present invention, the polymer having a low critical solution temperature is selected from any one of poly[2-(2-methoxyethoxy)ethoxymethacrylate], poly(N-isopropylacrylamide), poly(methyl vinyl ether) or polydimethylaminoethyl methacrylate.
[0028] In some embodiments of the present invention, the conductive material is selected from any one of metal nanomaterials, carbon materials or conductive polymers.
[0029] In some embodiments of the present invention, the metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets.
[0030] In some embodiments of the present invention, the carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials.
[0031] In some embodiments of the present invention, the conductive polymer is selected from any one of polypyrrole, polyaniline, and PEDOT:PSS materials.
[0032] In some embodiments of the present invention, the thickness of the porous material layer loaded with a polymer having a high critical solution temperature is 5 μm to 100 μm, the thickness of the porous material layer loaded with a polymer having a low critical solution temperature is 30 μm to 500 μm; the thickness of the conductive material layer is 100 nm to 500 μm.
[0033] In some embodiments of the present invention, the polymer with a high critical solution temperature is poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide] (PDMAPS), and the polymer with a low critical solution temperature is poly(N-isopropylacrylamide) (PNIPAM). The transition temperatures of these two thermosensitive polymers are similar, so when the temperature approaches the critical temperature, the wettability gradient changes at the same time, achieving a reversible wettability gradient that changes with temperature, which can be used to prepare an electronic skin with reversible unidirectional water transport with temperature response.
[0034] Some embodiments of the present invention also provide a method for preparing the intelligent humidity-regulating flexible electrode, which comprises the following steps in sequence: S1: using any one of thermally initiated free radical polymerization or photoinitiated free radical polymerization to introduce a polymer with a high critical solution temperature into a porous material to obtain a porous material layer loaded with a polymer with a high critical solution temperature; S2: using any one of thermally initiated free radical polymerization or photoinitiated free radical polymerization to introduce a polymer with a low critical solution temperature into a porous material to obtain a porous material layer loaded with a polymer with a low critical solution temperature; S3: bonding the porous material layer loaded with a high critical solution temperature polymer and the porous material layer loaded with a low critical solution temperature polymer together, spraying deionized water from one side of the porous material layer loaded with a low critical solution temperature polymer, and drying at room temperature to bond the two layers of material together to obtain a composite porous membrane; S4: on the side of the porous material layer loaded with a polymer with a low critical solution temperature of the composite porous membrane, preparing a conductive material layer by any one of magnetron sputtering, vacuum evaporation, electrostatic spraying or impregnation to obtain the intelligent humidity-regulating flexible electrode.
[0035] The following is an example of an implementation of the present invention:
[0036] Example 1
[0037] Cellulose acetate membrane (CA) was prepared by electrospinning, and cellulose membrane (CM) was obtained by hydrolysis of cellulose acetate membrane. CA and CM raw materials are easy to obtain and cheap, and CA and CM molecules contain a large number of hydroxyl groups, which are conducive to the grafting of thermosensitive polymers. Poly(N-isopropylacrylamide) (PNIPAM) with a low critical solution temperature and poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide] (PDMAPS) with a high critical solution temperature were grafted on the surfaces of CA and CM, respectively, by thermally initiated free radical polymerization, so that both membranes have temperature responsiveness. Then, the two membranes were bonded together, and conductive polypyrrole (PPy) was grown on one side of PNIPAM@CA by electrostatic spraying and in-situ polymerization, thereby preparing a smart humidity-controlled flexible electrode (PPy@PNIPAM@CA / PDMAPS@CM).
[0038] The following performance tests were performed on the intelligent humidity control flexible electrode prepared above:
[0039] 1. Detection of wettability changes of flexible electrodes at high and low temperatures:
[0040] Detection steps: Add 5 μL of water on the fiber membrane, test the contact angle of the fiber membrane with an optical contact angle meter, and take the average value at 5 random locations.
[0041] Test results: Figure 1 This is an electron microscope image of the wettability change of the flexible electrode at high and low temperatures, showing the wettability of different material layers in the flexible electrode at high and low temperatures. Among them, 1-a shows that the PNIPAM@CA layer is hydrophilic at low temperatures, 1-b shows that the PNIPAM@CA layer is hydrophobic at high temperatures, 1-c shows that the PDMAPS@CM layer is hydrophobic at low temperatures, and 1-d shows that the PDMAPS@CM layer is hydrophilic at high temperatures.
[0042] 2. Detection of changes in water transfer performance of flexible electrodes at high and low temperatures:
[0043] Detection steps: 10 μL of ink was dropped from the PNIPAM@CA layer at high and low temperatures, and the optical image of the fiber membrane and the transport process of the liquid on the membrane were recorded with a digital camera.
[0044] Test results: Figure 2 This is an electron microscope image of the change in water transfer performance of the flexible electrode at high and low temperatures, showing the water transfer performance of the flexible electrode at high and low temperatures. Among them, 2-a shows that when water is dripped from the PNIPAM@CA layer, water penetrates from the PNIPAM@CA layer to the PDMAPS@CM layer at high temperature and diffuses in the PDMAPS@CM layer, that is, sweating occurs; 2-b shows that at low temperatures, water cannot penetrate from the PNIPAM@CA layer to the PDMAPS@CM layer, and only diffuses in the PNIPAM@CA layer, that is, moisturizing occurs.
[0045] 3. Water vapor transmission rate test of flexible electrodes at high and low temperatures:
[0046] Test steps: Cover the electrode on a permeable cup filled with distilled water, weigh it with a balance, and place it in a standard environmental chamber to record the change in mass over time. The change in mass within a time interval is divided by the area of the electrode and the time interval to obtain the water vapor transmission rate.
[0047] Test results: Figure 3 is the water vapor permeation curve of the flexible electrode at high temperature and low temperature; Figure 3 It can be seen that the water vapor permeability of the electrode increases with time at both high and low temperatures, and it can be calculated that the water vapor permeability at high temperature is 421 g m -2 h -1 The water vapor transmission rate at low temperature is 56g m -2 h -1 .
[0048] 4. Electrode monitoring of skin hydration and temperature changes:
[0049] Detection steps: When monitoring the real-time hydration level of the human skin surface, it is necessary to first test the relationship curve between the hydration level and the impedance. By testing the impedance change curve with frequency at different hydration levels, it is then converted into a relationship curve between impedance and hydration level. When monitoring the hydration level in real time, first test the impedance change, and then convert the tested impedance into the hydration level according to the impedance-hydration level relationship curve to obtain a real-time hydration level curve.
[0050] Test results: Figure 4 The intelligent humidity control flexible electrode in Example 1 monitors the skin hydration and temperature changes when the environment changes from low temperature to high temperature, wherein 4-a shows the hydration change and 4-b shows the temperature change. The flexible electrode can monitor the skin hydration and temperature changes. When the environment changes from low temperature to high temperature, the hydration and temperature gradually increase.
[0051] 5. Changes in optical transmittance of the electrode-loaded thermosensitive polymer solution with temperature:
[0052] Detection steps: PNIPAM and PDMAPS were prepared into a 5 mg / mL aqueous solution, and the transmittance of the solution at different temperatures was tested using a UV spectrophotometer. The temperature corresponding to when the transmittance decreased / increased by half was the minimum / maximum critical temperature.
[0053] Figure 5 It is the change of optical transmittance of the thermosensitive polymer solution loaded with the intelligent humidity-controlled flexible electrode with temperature. Among them, 5-a shows the change of optical transmittance of PNIPAM solution with temperature, and 5-b shows the change of optical transmittance of PDMAPSPPNIPAM solution with temperature.
[0054] The test results show that the lowest critical temperature of PNIPAM is about 25°C, and the highest critical temperature of PDMAPS is about 28°C. The critical temperatures of the two polymers are close.
[0055] The above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.
Claims
1. An intelligent humidity control flexible electrode, characterized in that: include: A porous material layer supporting a polymer having a high critical solution temperature, a porous material layer supporting a polymer having a low critical solution temperature, and a conductive material layer.
2. The intelligent humidity control flexible electrode according to claim 1, characterized in that: The porous material in the porous material layer is selected from any one of cellulose acetate film, cellulose film, cotton cloth, polyacrylonitrile or silk.
3. The intelligent humidity control flexible electrode according to claim 1, characterized in that: The polymer having a high critical solution temperature is selected from any one of poly[2-(methacryloyloxy)ethyldimethyl-(3-sulfopropyl)ammonium hydroxide], poly(acryloyl asparagine), poly(acrylonitrile-co-acrylamide) or poly(N-isopropylacrylamide)-b-poly[3-(N-(3-methacrylamidepropyl)N,N-dimethyl)aminopropane sulfonate].
4. The intelligent humidity control flexible electrode according to claim 1, characterized in that: The polymer having a low critical solution temperature is selected from any one of poly[2-(2-methoxyethoxy)ethoxymethacrylate], poly(N-isopropylacrylamide), poly(methyl vinyl ether) or polydimethylaminoethyl methacrylate.
5. The intelligent humidity control flexible electrode according to claim 1, characterized in that: The conductive material is selected from any one of metal nanomaterials, carbon materials or conductive polymers.
6. The intelligent humidity control flexible electrode according to claim 5, characterized in that: The metal nanomaterial is selected from any one of metal nanoparticles, metal nanowires or metal nanosheets.
7. The intelligent humidity control flexible electrode according to claim 5, characterized in that: The carbon material is selected from any one of carbon nanotubes, carbon black, graphene or Mxene materials.
8. The intelligent humidity control flexible electrode according to claim 5, characterized in that: The conductive polymer is selected from any one of polypyrrole, polyaniline and PEDOT:PSS materials.
9. The intelligent humidity control flexible electrode according to claim 1, characterized in that: The thickness of the porous material layer loaded with a polymer having a high critical solution temperature is 5 μm to 100 μm, the thickness of the porous material layer loaded with a polymer having a low critical solution temperature is 30 μm to 500 μm; the thickness of the conductive material layer is 100 nm to 500 μm.
10. The method for preparing the intelligent humidity control flexible electrode according to any one of claims 1 to 9, characterized in that: The steps include: S1: introducing a polymer having a high critical solution temperature into a porous material by using any one of heat-induced free radical polymerization or light-induced free radical polymerization to obtain a porous material layer loaded with the polymer having a high critical solution temperature; S2: introducing a polymer having a low critical solution temperature into a porous material by using any one of heat-induced free radical polymerization and light-induced free radical polymerization to obtain a porous material layer loaded with the polymer having a low critical solution temperature; S3: laminating a porous material layer loaded with a high critical solution temperature polymer and a porous material layer loaded with a low critical solution temperature polymer, spraying deionized water from one side of the porous material layer loaded with the low critical solution temperature polymer, and drying at room temperature to laminate the two layers of material together to obtain a composite porous membrane; S4: On the porous material layer side of the composite porous membrane loaded with a polymer having a low critical solution temperature, a conductive material layer is prepared by any one of magnetron sputtering, vacuum evaporation, electrostatic spraying or impregnation methods to obtain the intelligent humidity-regulating flexible electrode.