Visual multifunctional humidity-strain sensor and preparation method and application thereof

Abstract

The application provides a visual multifunctional humidity-strain sensor and a preparation method and application thereof, and belongs to the technical field of humidity-strain sensor preparation. The preparation method provided by the application uniformly mixes a perovskite solution and a polymer solution to obtain a perovskite polymer composite spinning solution; hydrophilic conductive material and hydrophilic polymer are dissolved in a hydrophilic solvent to obtain a uniform composite conductive spinning solution; then, the perovskite polymer composite spinning solution is extruded into a coagulation bath to be primarily solidified into a fiber through a combination of a wet spinning method and an immersion method, and then immediately immersed into the composite conductive spinning solution; finally, heat treatment is performed to obtain a visual multifunctional humidity-strain sensor with a skin-core structure. The sensor has adjustable fluorescence color and resistance, high fluorescence intensity, good uniformity and stability, good temperature resistance of the electron in the conductive layer, good storage stability, excellent humidity and strain response performance, fast response speed, high sensitivity, and small sensing hysteresis.

Description

Technical Field

[0001] This invention relates to the field of humidity-strain sensor fabrication technology, specifically to a visual multifunctional humidity-strain sensor, its fabrication method, and its application. Background Technology

[0002] With the continuous development of sensors and their manufacturing technologies, and the increasing demands of human beings, integration, multifunctionality, intelligence, and miniaturization have become important directions in sensor research. Among these, multifunctional flexible sensing devices, which integrate multiple sensing elements with different functions by leveraging the flexible characteristics of textiles, not only possess excellent flexibility and extensibility, allowing them to be freely bent or even folded for adaptive adjustments based on application scenarios, but also simultaneously measure multiple parameters, reflecting the overall state of the sample. These devices have broad application prospects in fields ranging from smart wearable devices to medical health monitoring.

[0003] While there is considerable research on flexible sensors in the existing technology, many technical problems remain to be solved. On the one hand, although high-sensitivity flexible sensors already exist, interfacial mismatch between the conductive material and the flexible substrate can lead to peeling or delamination of the conductive layer under mechanical forces, thus affecting the sensor's durability. On the other hand, the fabrication of flexible sensors is generally complex and expensive, limiting their commercial application. Therefore, to meet the diverse needs of practical applications, finding a simple and low-cost method to fabricate multifunctional, high-performance flexible sensors using fiber substrates remains a significant challenge.

[0004] In view of this, it is necessary to design a visual multifunctional humidity-strain sensor and its fabrication method and application to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a visualized multifunctional humidity-strain sensor based on perovskite fluorescent filaments, its preparation method and application, and a core-shell structure visualized multifunctional humidity-strain sensor prepared by combining wet spinning and impregnation methods. This humidity-strain sensor achieves visualization and high tensile strength through a high-fluorescence perovskite polymer composite elastic core layer, and obtains good conductivity through a hydrophilic composite conductive layer, realizing humidity sensing and tensile sensing.

[0006] In a first aspect, embodiments of this application provide a method for fabricating a visual multifunctional humidity-strain sensor, comprising the following steps:

[0007] S1, the perovskite solution and the polymer solution are mixed uniformly to obtain the perovskite-polymer composite spinning solution;

[0008] S2, dissolve hydrophilic conductive materials and hydrophilic polymers in a hydrophilic solvent to obtain a uniform composite conductive spinning solution;

[0009] S3. Using a wet spinning method, the perovskite polymer composite spinning solution obtained in step S1 is extruded into a coagulation bath to initially solidify into fibers, obtaining a core layer. Before the core layer is completely solidified and dried, it is quickly immersed in the composite conductive spinning solution obtained in step S2, so that the core layer is fully and uniformly coated with a conductive layer, obtaining a composite fiber filament. Then, heat treatment is performed to dry and solidify the composite fiber filament and further crystallize the core layer material. After natural cooling, a visual multifunctional humidity-strain sensor with a core-skin structure is obtained.

[0010] Further, in the perovskite solution described in step S1, the concentration of perovskite is 0.005-4.0 mmol / mL, and the perovskite is a mixture of AX and PbX2; wherein, the molar ratio of AX to PbX2 is 1:(0.5-2), A is one or more of cesium, methylamine, and ethylamine, and X is one or more of I, Cl, and Br; the solvent of the perovskite solution is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and γ-butyrolactone.

[0011] Furthermore, in the polymer solution described in step S1, the concentration of the polymer is 5-50 wt%, and the polymer is polyurethane, polyacrylonitrile, or polyvinyl chloride; the solvent of the polymer solution is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and γ-butyrolactone; in step S1, the volume ratio of the perovskite solution to the polymer solution is 1:(1-30).

[0012] Furthermore, in step S2, the hydrophilic conductive material is one or more of carbon nanotubes, carbon black, graphene, MXene, silver nanowires, and silver nanoparticles; the hydrophilic polymer is one or more of sodium polyacrylate, polyvinyl alcohol, and polyethylene glycol; and the hydrophilic solvent is water, ethanol, or isopropanol.

[0013] Furthermore, the concentration of the hydrophilic conductive material in the composite conductive spinning solution is 0.1-20 wt%, and the concentration of the hydrophilic polymer in the composite conductive spinning solution is 0.01-5 wt%.

[0014] Furthermore, in step S3, the coagulation bath is water at room temperature, and the temperature of the heat treatment is lower than or equal to 180°C.

[0015] Secondly, embodiments of this application provide a visual multifunctional humidity-strain sensor, fabricated using any one of the aforementioned methods. The visual multifunctional humidity-strain sensor has a core-skin structure; wherein the core layer is a composite fluorescent elastic material prepared from perovskite and polymer, and the skin layer is a composite conductive material prepared from water-based conductive material and hydrophilic polymer, and the skin layer is a humidity-strain sensing layer; the visual multifunctional humidity-strain sensor has photoluminescence properties, and the fluorescence emitted by the core layer under ultraviolet light irradiation penetrates the skin layer structure, making the fluorescence of the visual multifunctional humidity-strain sensor visible.

[0016] Furthermore, the photoluminescence color of the visualized multifunctional humidity-strain sensor is controlled by changing the type and proportion of X element contained in the core layer; the photoluminescence fluorescence intensity of the visualized multifunctional humidity-strain sensor decreases by less than 5% after being stored in air with constant temperature and humidity for 30 days; and the photoluminescence fluorescence intensity decreases by less than 5% after the visualized multifunctional humidity-strain sensor is repeatedly stretched to a length deformation of 200% for 1000 cycles.

[0017] Furthermore, the resistance of the visualized multifunctional humidity-strain sensor is adjusted by changing the proportion of conductive material in the cortex, with the resistance adjustment range between 100Ω and 1MΩ; the normalized resistance change rate of the visualized multifunctional humidity-strain sensor in an environment with a humidity of 23-95%RH is greater than or equal to 120%; the normalized resistance change rate of the visualized multifunctional humidity-strain sensor is less than 10% after being stored in air with constant temperature and humidity for 24 days; and the normalized resistance change rate of the visualized multifunctional humidity-strain sensor is less than 10% when the storage temperature is increased from 15℃ to 45℃.

[0018] Thirdly, embodiments of this application provide a visual multifunctional humidity-strain sensor prepared by any of the foregoing methods or an application of the visual multifunctional humidity-strain sensor prepared by any of the foregoing methods. The visual multifunctional humidity-strain sensor is used for monitoring human physiological activities, flexible pattern display, encryption and anti-counterfeiting, detecting skin humidity, non-contact switching, and hazard warning.

[0019] The beneficial effects of this application are as follows:

[0020] This application provides a visualized multifunctional humidity-strain sensor, its fabrication method, and its application. A core-shell structure is fabricated using a combination of wet spinning and impregnation methods to obtain the visualized multifunctional humidity-strain sensor. This humidity-strain sensor achieves visualization and high tensile strength through a high-fluorescence perovskite polymer composite elastic core layer, and obtains good conductivity through a hydrophilic composite conductive layer, realizing both humidity sensing and tensile sensing.

[0021] (1) The visualized multifunctional humidity-strain sensor prepared in this application exhibits excellent humidity and strain response performance, fast response speed, high sensitivity, and low sensing hysteresis. The normalized resistance change rate of this visualized multifunctional humidity-strain sensor is greater than or equal to 120% in an environment with a humidity range of 23-95%RH. When the strain range is between 0-95%, GF1 can reach 2.9; when the strain range is between 95-200%, GF2 can reach 27. The response / recovery time of this visualized multifunctional humidity-strain sensor to strain can reach 0.2s / 0.3s.

[0022] (2) The method for preparing the visual multifunctional humidity-strain sensor provided in this application is low in cost, simple in process, easy to scale up for production, and the fluorescence color of the visual multifunctional humidity-strain sensor can be controlled by adjusting the proportion and type of perovskite raw materials, and the resistance of the visual multifunctional humidity-strain sensor can be controlled by adjusting the proportion of conductive material in the skin layer.

[0023] (3) The visualized multifunctional humidity-strain sensor prepared in this application has excellent luminescence brightness and a wide color gamut, with rich and tunable fluorescence colors, including blue, green, red, and yellow. The fluorescence of this visualized multifunctional humidity-strain sensor can penetrate the skin layer, making the sensor exhibit clear and bright fluorescence for visualization. Furthermore, the fluorescence intensity is high, and the uniformity and stability are good. When the visualized multifunctional humidity-strain sensor is stored in air with constant temperature and humidity for 30 days, the fluorescence intensity and uniformity of the photoluminescence remain essentially unchanged, with a fluorescence intensity decrease rate of less than 5%. After repeatedly stretching the sensor to a length deformation of 200% and cycling it 1000 times, the fluorescence intensity decrease rate of the photoluminescence is less than 5%.

[0024] (4) The visualized multifunctional humidity-strain sensor prepared in this application has a wide resistance adjustment range between 100Ω and 1MΩ, and the conductive layer has good electronic temperature resistance and storage stability. When the visualized multifunctional humidity-strain sensor is stored in air with constant temperature and humidity for 24 days, the normalized resistance change rate is less than 10%; when the storage temperature is increased from 15℃ to 45℃, the normalized resistance change rate of the sensor is less than 10%.

[0025] (5) The visual multifunctional humidity-strain sensor prepared in this application has good mechanical properties and can be used for monitoring human physiological activities, flexible pattern display, encryption and anti-counterfeiting, detecting skin humidity, non-contact switch and hazard warning.

[0026] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0028] Figure 1 Digital photographs of the visualized multifunctional humidity-strain sensor prepared in Example 1 of this application stretched to different deformation states under natural light and ultraviolet light;

[0029] Figure 2 The resistance change graph of the visualized multifunctional humidity-strain sensor prepared in Example 1 of this application was stored in air at 15°C and 23% relative humidity for 24 days.

[0030] Figure 3 Digital photographs of the visualized multifunctional humidity-strain sensors obtained in Examples 1-3 of this application under natural light and ultraviolet light, from left to right: Example 1 (green), Example 2 (red), and Example 3 (blue);

[0031] Figure 4 Example 1 of this application is a digital photograph showing the integration of a visual multi-functional humidity-strain sensor onto a fabric substrate;

[0032] Figure 5 Example 2 of this application uses a visualized multifunctional humidity-strain sensor to obtain a relative resistance change graph from breathing pattern detection;

[0033] Figure 6 The visual multifunctional humidity-strain sensor prepared in Example 4 of this application stores a resistance change graph for 24 days in air at a temperature of 15°C and a relative humidity of 69%.

[0034] Figure 7The graph shows the resistance change of the visualized multifunctional humidity-strain sensor prepared in Example 4 of this application as the ambient temperature increases from 15°C to 45°C in air with a relative humidity of 69%. Detailed Implementation

[0035] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0037] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more (including two), unless otherwise explicitly defined.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] While there is considerable research on flexible sensors in the existing technology, many technical problems remain to be solved. On the one hand, although high-sensitivity flexible sensors already exist, interfacial mismatch between the conductive material and the flexible substrate can lead to peeling or delamination of the conductive layer under mechanical forces, thus affecting the sensor's durability. On the other hand, the fabrication of flexible sensors is generally complex and expensive, limiting their commercial application. Therefore, to meet the diverse needs of practical applications, finding a simple and low-cost method to fabricate multifunctional, high-performance flexible sensors using fiber substrates remains a significant challenge.

[0041] To address the aforementioned technical issues, this application provides a visualized multifunctional humidity-strain sensor, its fabrication method, and its application. A core-shell structure is combined with a wet spinning method to fabricate the visualized multifunctional humidity-strain sensor, resulting in low fabrication cost, a simple process, and ease of scale-up production. The fabricated humidity-strain sensor achieves visualization and high tensile strength through a high-fluorescence perovskite polymer composite elastic core layer, and good conductivity through a hydrophilic composite conductive layer, enabling both humidity and tensile sensing.

[0042] In a first aspect, embodiments of this application provide a method for fabricating a visual multifunctional humidity-strain sensor, comprising the following steps.

[0043] S1, the perovskite solution and the polymer solution are mixed uniformly to obtain a perovskite-polymer composite spinning solution.

[0044] In some embodiments, the volume ratio of the perovskite solution to the polymer solution is 1:(1-30).

[0045] The perovskite concentration in the perovskite solution ranges from 0.005 to 4.0 mmol / mL, and the perovskite is a mixture of AX and PbX2. The molar ratio of AX to PbX2 is 1:(0.5-2), where A is one or more of cesium, methylamine, and ethylamine, and X is one or more of I, Cl, and Br. The solvent for the perovskite solution is one or more of DMF, DMSO, NMP, and GBL.

[0046] The polymer in the polymer solution is PU, PAN, or PVC, and the polymer concentration is 5-50 wt%. The solvent of the polymer solution is one or a mixture of DMF, DMSO, NMP, and GBL.

[0047] S2, dissolve the hydrophilic conductive material and hydrophilic polymer in a hydrophilic solvent to obtain a uniform composite conductive spinning solution.

[0048] In some embodiments, the hydrophilic conductive material is one or more of carbon nanotubes, carbon black, graphene, MXene, silver nanowires, and silver nanoparticles. The concentration of the hydrophilic conductive material in the composite conductive spinning solution is 0.1-20 wt%.

[0049] In some embodiments, the hydrophilic polymer is PAAS, PVA, or PEG, and the concentration of the hydrophilic polymer in the composite conductive spinning solution is 0.01-5 wt%. The solvent used in step S2 is water, ethanol, or isopropanol.

[0050] S3. Using a wet spinning method, the perovskite polymer composite spinning solution obtained in step S1 is extruded into a coagulation bath to initially solidify into fibers, obtaining a core layer. Before the core layer is completely solidified and dried, it is quickly immersed in the composite conductive spinning solution obtained in step S2, so that the core layer is fully and uniformly coated with a conductive layer, obtaining a composite fiber filament. Then, heat treatment is performed to dry and solidify the composite fiber filament and further crystallize the core layer material. After natural cooling, a visual multifunctional humidity-strain sensor with a core-skin structure is obtained.

[0051] In some embodiments, the coagulation bath is water at room temperature. The heat treatment temperature of the composite fiber filament is below or equal to 180°C. Further, the heat treatment temperature is 50-180°C, and the heat treatment time is adjusted within the range of 10 min-24 h depending on the heat treatment temperature. Specifically, the heat treatment time decreases as the heat treatment temperature increases and increases as the heat treatment temperature decreases. In the actual preparation process, it is sufficient to ensure that the composite fiber filament is completely dry and cured during the heat treatment process.

[0052] Secondly, embodiments of this application provide a visual multifunctional humidity-strain sensor, which is fabricated according to the aforementioned method. This visual multifunctional humidity-strain sensor has a core-skin structure. The core layer is a composite fluorescent elastic material prepared from perovskite and a polymer, and the skin layer is a composite conductive material prepared from an aqueous conductive material and a hydrophilic polymer. The skin layer serves as the humidity-strain sensing layer. This visual multifunctional humidity-strain sensor exhibits photoluminescence properties, and the fluorescence emitted by the core layer under ultraviolet light penetrates the skin layer structure, making the fluorescence of the visual multifunctional humidity-strain sensor visible.

[0053] In some embodiments, the photoluminescence color of the visualized multifunctional humidity-strain sensor provided in this application is controlled by changing the type and proportion of X element contained in the core layer. Furthermore, the control range of the photoluminescence color is the blue light gamut, green light gamut, red light gamut, and yellow light gamut.

[0054] In some embodiments, when the visual multifunctional humidity-strain sensor is stored in air with constant temperature and humidity for 30 days, the fluorescence intensity and uniformity of photoluminescence remain essentially unchanged, and the decrease rate of fluorescence intensity is less than 5%. After repeatedly stretching the visual multifunctional humidity-strain sensor to a length deformation of 200% for 1000 cycles, the decrease rate of fluorescence intensity of photoluminescence is less than 5%.

[0055] In some embodiments, the resistance of the visual multifunctional humidity-strain sensor provided in this application is adjusted within the range of 100Ω-1MΩ by changing the proportion of conductive material in the cortex. The normalized resistance change rate of this visual multifunctional humidity-strain sensor is greater than or equal to 120% in an environment with a humidity of 23-95%RH.

[0056] In some embodiments, when the visual multi-functional humidity-strain sensor is stored in air with constant temperature and humidity for 24 days, the normalized resistance change rate is less than 10%. When the storage temperature is increased from 15°C to 45°C, the normalized resistance change rate of the visual multi-functional humidity-strain sensor is less than 10%.

[0057] Thirdly, embodiments of this application provide an application of a visual multifunctional humidity-strain sensor, which is used for monitoring human physiological activities, flexible pattern display, encryption and anti-counterfeiting, detecting skin humidity, non-contact switching, and hazard warning.

[0058] In some embodiments, the visual multifunctional humidity-strain sensor provided in this application is applied to the fields of flexible pattern display and encryption anti-counterfeiting. By combining visual multifunctional humidity-strain sensors with different fluorescent colors and weaving them onto a flexible substrate, a flexible pattern can be obtained, and this flexible pattern exhibits different patterns under natural light and ultraviolet light. By combining the specific pattern exhibited under ultraviolet light with a specific arrangement, a specific combination of numbers or a specific combination of letters / words can be obtained.

[0059] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0060] Example 1

[0061] Example 1 provides a method for fabricating a visual multifunctional humidity-strain sensor, comprising the following steps:

[0062] S1. First, a perovskite solution is prepared by mixing CsBr and PbBr2 at a molar ratio of 1:1 to obtain perovskite. The perovskite is then added to DMF to obtain a perovskite solution with a concentration of 0.04 mmol / mL. Next, a polymer solution (PU solution) is prepared by adding PU to DMF to obtain a PU solution with a concentration of 20 wt%. Finally, the perovskite solution and the PU solution are uniformly mixed at a volume ratio of 2:5 to obtain a perovskite-polymer composite spinning solution.

[0063] S2, add hydrophilic conductive material CNT and hydrophilic polymer PAAS to deionized water and mix evenly to obtain a composite conductive spinning solution with a conductive material concentration of 1wt% and a PAAS concentration of 1wt%.

[0064] In step S3, using a wet spinning method, the perovskite polymer composite spinning solution obtained in step S1 is extruded into a coagulation bath (room temperature water) to initially solidify into fibers, obtaining a core layer. Before the core layer is completely solidified and dried, it is rapidly immersed in the composite conductive spinning solution obtained in step S2, ensuring a thorough and uniform coating of the conductive layer on the outside of the core layer, resulting in a preliminary composite fiber filament. This filament is then heat-treated at 60°C for 0.5 hours to dry and solidify. Simultaneously, the heat treatment promotes the crystallization of the perovskite material in the luminescent layer (core layer). After natural cooling, a core-shell structure with visualized multifunctional humidity-strain sensor is obtained.

[0065] The photoluminescence color of the visualized multifunctional humidity-strain sensor prepared in Example 1 is green. The sensor was stretched by hand to deformation rates of 0%, 50%, 100%, 150%, and 200%, respectively. Please refer to... Figure 1 The image shows digital photographs of the visualized multifunctional humidity-strain sensor stretched to different deformation states under natural light and ultraviolet light. It can be seen that the sensor has good stretchability and maintains good fluorescence uniformity even under stretched conditions. The fluorescence intensity of the sensor decreases as the deformation rate increases.

[0066] The visualized multifunctional humidity-strain sensor prepared in Example 1 was stretched by hand to a deformation rate of 200%, then released to allow it to spring back to its original shape. This process was repeated 1000 times, and the fluorescence intensity of the sensor decreased by 1.8%.

[0067] Example 2

[0068] The difference between Example 2 and Example 1 is that in step S1, the perovskite used is MAPbI3 (MA refers to amine ions), while the rest is basically the same as in Example 1, and will not be repeated here. The photoluminescence color of the visualized multifunctional humidity-strain sensor prepared in Example 2 is red.

[0069] Example 3

[0070] The difference between Example 3 and Example 1 is that in step S1, the perovskite is made of CsPbCl. 1.5 Br 1.5 The rest is basically the same as in Example 1, and will not be repeated here. The photoluminescence color of the visualized multifunctional humidity-strain sensor prepared in Example 3 is blue light.

[0071] The sensing and conductivity properties of the visualized multifunctional humidity-strain sensor provided in this application are only related to the composite conductive layer and not to the core layer (light-emitting layer). The sensing performance of the visualized multifunctional humidity-strain sensors prepared in Examples 1-3 is consistent. Therefore, the performance of the visualized multifunctional humidity-strain sensor prepared in Example 1 was tested as follows:

[0072] (1) The initial resistance of the visualized multifunctional humidity-strain sensor was measured to be 60±2kΩ.

[0073] (2) The visualized multifunctional humidity-strain sensor was stored in air at 15°C and 23% relative humidity for 24 days, and the normalized resistance change of the visualized multifunctional humidity-strain sensor during the storage process was tested. The test results are shown in [reference]. Figure 2 As shown, the visualized multifunctional humidity-strain sensor prepared in Example 1 has good storage stability. After being stored in air for 24 days, the normalized resistance change rate is less than 2%.

[0074] (3) The visualized multifunctional humidity-strain sensor was placed in air with a relative humidity of 23%, and the ambient temperature was increased from 15℃ to 45℃. The normalized resistance change of the visualized multifunctional humidity-strain sensor was tested during the heating process. The normalized resistance change rate was 5%, which shows that the visualized multifunctional humidity-strain sensor has good temperature resistance.

[0075] (4) The humidity sensing performance of the visualized multifunctional humidity-strain sensor was tested: The visualized multifunctional humidity-strain sensor was placed in a humidity chamber with pre-set relative humidity (RH = 23%, 35%, 45%, 55%, 65%, 75%, 85%, and 95%). The resistance change generated by the sensor in response to different humidity environments was recorded using an electrochemical workstation, and the resistance change rate (ΔR = [(R...]) was calculated. x -R0) / R0] × 100%, of which R x(R0 is the initial resistance, where R0 is the real-time resistance). Test results: In an environment with a humidity range of 23-95% RH, the relative resistance change rate of the visualized multi-functional humidity-strain sensor is 130%, and the humidity hysteresis value is 3.5%.

[0076] (5) The strain sensing performance of the visualized multifunctional humidity-strain sensor was tested: the visualized multifunctional humidity-strain sensor was subjected to tensile stresses of different deformations using a strength tester, and the resistance changes of the sensor due to different deformations were recorded using an electrochemical workstation. The GF value was calculated (GF = [(R x -R0) / R0] / ε, where ε is strain and GF is the ratio of relative resistance change to strain). Test results: When the strain range is between 0-95%, GF1=2.9; when the strain range is between 95-200%, GF2=27; the response / recovery time of this visual multi-functional humidity-strain sensor to strain is 0.2s / 0.3s.

[0077] Please see Figure 3 The images shown are digital photographs of the visualized multifunctional humidity-strain sensors prepared in Examples 1-3 under natural light and ultraviolet light. From left to right, they are Example 1 (green), Example 2 (red), and Example 3 (blue).

[0078] The visualized multifunctional humidity-strain sensors prepared in Examples 1-3 were stored in air at 15°C and 23% relative humidity for 30 days, and their fluorescence intensity changes were tested. The rate of decrease in fluorescence intensity is shown in the table below.

[0079]

[0080]

[0081] Application Example 1

[0082] Application Example 1 provides an application of a visual multifunctional humidity-strain sensor in the fields of flexible pattern display and anti-counterfeiting. The visual multifunctional humidity-strain sensors prepared in Examples 1-3 are woven together onto a black flexible substrate to present the number 8. Specifically, the visual multifunctional humidity-strain sensor prepared in Example 1 is woven into two vertical lines to form the number pattern "1"; the visual multifunctional humidity-strain sensor prepared in Example 2 is woven into a horizontal line at the top, two horizontal lines in the middle, two horizontal lines at the bottom, and a vertical line to the right of the aforementioned horizontal line to form the number pattern "3"; the visual multifunctional humidity-strain sensor prepared in Example 3 is woven into an intersecting horizontal line and a vertical line to form the number pattern "7"; and the number patterns "1", "3", and "7" are combined to form the digital number "8" in double-line font.

[0083] Please see Figure 4 The image shown is a digital photograph visualizing a multi-functional humidity-strain sensor integrated onto a fabric substrate. Figure 4 Photo 'a' was taken under natural light. Figure 4 b was obtained under ultraviolet light. The pattern obtained in Example 1 has colors similar to a black background under natural light, but under ultraviolet light, it produces numbers of different colors: green "1", red "3", blue "7", and colored "8". Combining these with specific permutations yields specific number combinations. For example, when the password is set to "red-green-blue-colored", the resulting number combination is 3178.

[0084] Application Example 2

[0085] Application Example 2 provides an example of a visual multifunctional humidity-strain sensor used in testing breathing patterns. The sensor is installed inside a mask, and when breathing while wearing the mask, the sensor responds to humidity changes by generating real-time resistance changes.

[0086] Please see Figure 5 The image shows the relative resistance change obtained from breathing pattern detection. It can be seen that mouth breathing has a much greater impact on the relative resistance change than nasal breathing. This is because mouth breathing releases more water molecules, resulting in a larger resistance change in the visualized multi-functional humidity-strain sensor. Similarly, by analyzing the magnitude of the resistance change, changes in breathing rate can be further detected.

[0087] Example 4

[0088] Example 4 provides a method for fabricating a visual multifunctional humidity-strain sensor, comprising the following steps:

[0089] S1, First, prepare a perovskite solution. Specifically, mix CsBr and PbBr2 in a molar ratio of 1:1 to obtain perovskite. Add the perovskite to a DMF-DMSO mixed solvent (V... DMF V DMSO A perovskite solution with a concentration of 0.04 mmol / mL was obtained by mixing PU with a DMF-DMSO mixed solvent (V = 9:1). Then, a polymer solution (PU solution) was prepared by adding PU to a DMF-DMSO mixed solvent (V = 9:1). DMF V DMSO A PU solution with a concentration of 20 wt% was obtained by mixing the perovskite solution and the PU solution at a volume ratio of 2:5 (9:1). Finally, the perovskite solution and the PU solution were uniformly mixed at a volume ratio of 2:5 to obtain the perovskite polymer composite spinning solution.

[0090] S2, CNT and CB are mixed at a molar ratio of 10:1 to obtain a conductive material. The conductive material and the hydrophilic polymer PAAS are added to deionized water and mixed evenly to obtain a composite conductive spinning solution with a conductive material concentration of 1 wt% and a PAAS concentration of 0.75 wt%.

[0091] In step S3, using a wet spinning method, the perovskite polymer composite spinning solution obtained in step S1 is extruded into a coagulation bath (room temperature water) to initially solidify into fibers, obtaining a core layer. Before the core layer is completely solidified and dried, it is rapidly immersed in the composite conductive spinning solution obtained in step S2, ensuring a thorough and uniform coating of the conductive layer on the outside of the core layer, resulting in a preliminary composite fiber filament. This filament is then heat-treated at 60°C for 0.5 hours to dry and solidify. Simultaneously, the heat treatment promotes the crystallization of the perovskite material in the luminescent layer (core layer). After natural cooling, a core-shell structure with visualized multifunctional humidity-strain sensor is obtained.

[0092] The photoluminescence color of the visualized multifunctional humidity-strain sensor prepared in Example 4 is green. The performance of the visualized multifunctional humidity-strain sensor prepared in Example 4 was tested as follows:

[0093] (1) The initial resistance of the visualized multi-functional humidity-strain sensor was tested to be 80±3kΩ.

[0094] (2) The sensor was stored in air at 15°C and 69% relative humidity for 24 days, and the change in normalized resistance of the sensor during the storage process was tested. The test results are shown in [reference needed]. Figure 6 As shown, the visualized multifunctional humidity-strain sensor prepared in Example 4 has good storage stability, with a normalized resistance change rate of 4% after 24 days of storage in air.

[0095] (3) Place the sensor in air with a relative humidity of 69% and raise the ambient temperature from 15℃ to 45℃. Test the change in the normalized resistance of the sensor during the heating process. The test results are shown in [reference needed]. Figure 7 As shown, the visualized multifunctional humidity-strain sensor prepared in Example 4 has good temperature stability, with a normalized resistance change rate of 4% when the temperature rises from 15°C to 45°C.

[0096] (4) The humidity sensing performance of the visualized multifunctional humidity-strain sensor was tested. Test results: In an environment with a humidity of 23-95%RH, the relative resistance change rate of the sensor was 127%, and the humidity hysteresis value was 3.8%.

[0097] (5) Test the strain sensing performance of the visualized multifunctional humidity-strain sensor. Test results: GF1 = 2.9 when the strain range is between 0-95%; GF2 = 25 when the strain range is between 95-200%; the response / recovery time of the sensor to strain is 0.3s / 0.3s.

[0098] Example 5

[0099] The difference between Example 5 and Example 4 is that the hydrophilic polymer used in step S2 is PEG, and the concentration of PEG in the composite conductive spinning solution is 0.5 wt%. The rest is basically the same as Example 4, and will not be repeated here.

[0100] The visualized multifunctional humidity-strain sensor prepared in Example 5 appears black under natural light and fluoresces green under ultraviolet light. The initial resistance of this visualized multifunctional humidity-strain sensor was measured to be 90 ± 5 kΩ. After storing the sensor in air at 15°C and 69% relative humidity for 24 days, the normalized resistance change rate was 8%.

[0101] The humidity sensing performance and strain sensing performance of the visualized multifunctional humidity-strain sensor prepared in Example 5 were tested and are as follows:

[0102] (1) Humidity sensing performance. In an environment with a humidity of 23-95%RH, the relative resistance change rate of this sensor is 125%, and the humidity hysteresis value is 7%.

[0103] (2) Strain sensing performance. When the strain range is between 0-95%, GF1 = 2.8; when the strain range is between 95-200%, GF2 = 27; the response / recovery time of the sensor to strain is 0.5s / 0.8s.

[0104] Example 6

[0105] The difference between Example 6 and Example 4 is that the conductive material used in step S2 is CNT, and the concentration of CNT in the composite conductive spinning solution is 12 wt%. The rest is basically the same as Example 4, and will not be repeated here.

[0106] The visualized multifunctional humidity-strain sensor prepared in Example 6 appears black under natural light and fluoresces green under ultraviolet light. The initial resistance of this visualized multifunctional humidity-strain sensor was measured to be 800 ± 25 Ω. After storing the sensor in air at 15°C and 69% relative humidity for 24 days, the normalized resistance change rate was 7%.

[0107] The humidity sensing performance and strain sensing performance of the visualized multifunctional humidity-strain sensor prepared in Example 6 were tested and obtained as follows:

[0108] (1) Humidity sensing performance. In an environment with a humidity of 23-95%RH, the relative resistance change rate of this sensor is 123%, and the humidity hysteresis value is 4%.

[0109] (2) Strain sensing performance. When the strain range is between 0-95%, GF1 = 2.0; when the strain range is between 95-200%, GF2 = 20; the response / recovery time of the sensor to strain is 0.3s / 0.3s.

[0110] Example 7

[0111] The difference between Example 7 and Example 4 is that the conductive material used in step S2 is CNT with a concentration of 0.5 wt%. The rest is basically the same as in Example 4, and will not be repeated here.

[0112] The visualized multifunctional humidity-strain sensor prepared in Example 7 is black under natural light and fluoresces green under ultraviolet light. The initial resistance of this visualized multifunctional humidity-strain sensor was measured to be 500 ± 20 kΩ. After storing the sensor in air at 15°C and 69% relative humidity for 24 days, the normalized resistance change rate was 6%.

[0113] The humidity sensing performance and strain sensing performance of the visualized multifunctional humidity-strain sensor prepared in Example 7 were tested and are as follows:

[0114] (1) Humidity sensing performance. In an environment with a humidity of 23-95%RH, the relative resistance change rate of this sensor is 122%, and the humidity hysteresis value is 5%.

[0115] (2) Strain sensing performance. When the strain range is between 0-95%, GF1 = 2.1; when the strain range is between 95-200%, GF2 = 21; the response / recovery time of the sensor to strain is 0.3s / 0.4s.

[0116] Example 8

[0117] The difference between Example 8 and Example 4 is that the conductive material used in step S2 is AgNW, with a concentration of 0.5 wt% in the composite conductive spinning solution; the polymer is PVA, with a concentration of 0.5 wt% in the composite conductive spinning solution. The rest is basically the same as in Example 4, and will not be repeated here.

[0118] The visualized multifunctional humidity-strain sensor prepared in Example 8 is silvery-white under natural light and fluoresces green under ultraviolet light. The initial resistance of this visualized multifunctional humidity-strain sensor was measured to be 10 ± 1 kΩ. After storing the sensor in air at 15°C and 69% relative humidity for 24 days, the normalized resistance change rate was 8.2%.

[0119] The humidity sensing performance and strain sensing performance of the visualized multifunctional humidity-strain sensor prepared in Example 7 were tested and are as follows:

[0120] (1) Humidity sensing performance. In an environment with a humidity of 23-95%RH, the relative resistance change rate of this sensor is 123%, and the humidity hysteresis value is 5%.

[0121] (2) Strain sensing performance. When the strain range is between 0-95%, GF1 = 2.0; when the strain range is between 95-200%, GF2 = 21; the response / recovery time of the sensor to strain is 0.3 / 0.4s.

[0122] The preparation methods of Examples 1-8 and the corresponding initial resistances of the obtained visualized multifunctional humidity-strain sensors are summarized in the table below.

[0123]

[0124] In summary, this application provides a visual multifunctional humidity-strain sensor and its fabrication method. A core-shell structure is prepared by combining wet spinning and impregnation methods to obtain the visual multifunctional humidity-strain sensor. The application of this sensor in flexible pattern display, anti-counterfeiting, and breathing pattern detection is also provided. The visual multifunctional humidity-strain sensor prepared in this application exhibits controllable fluorescence color and resistance, high fluorescence intensity, good uniformity and stability, and good electronic temperature resistance and storage stability of the conductive layer. The sensor demonstrates excellent humidity and strain response performance, with fast response speed, high sensitivity, and low sensing hysteresis. The normalized resistance change rate of this visual multifunctional humidity-strain sensor in an environment with humidity of 23-95%RH is greater than or equal to 120%. When the strain range is between 0-95%, GF1 can reach 2.9; when the strain range is between 95-200%, GF2 can reach 27. The response / recovery time of this visual multifunctional humidity-strain sensor to strain can reach 0.2s / 0.3s.

[0125] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for fabricating a visual multifunctional humidity-strain sensor, characterized in that, Includes the following steps: S1, a perovskite solution and a polymer solution are uniformly mixed to obtain a perovskite-polymer composite spinning solution; the concentration of perovskite in the perovskite solution is 0.005-4.0 mmol / mL, and the perovskite is a mixture of AX and PbX2; wherein the molar ratio of AX to PbX2 is 1:(0.5-2), A is one or more of cesium, methylamine, and ethylamine, and X is one or more of I, Cl, and Br; the solvent of the perovskite solution is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and γ-butyrolactone; the concentration of the polymer in the polymer solution is 5-50 wt%, and the polymer is polyurethane, polyacrylonitrile, or polyvinyl chloride; the volume ratio of the perovskite solution to the polymer solution is 1:(1-30). S2, a hydrophilic conductive material and a hydrophilic polymer are dissolved in a hydrophilic solvent to obtain a uniform composite conductive spinning solution; the hydrophilic conductive material is one or more of carbon nanotubes, carbon black, graphene, MXene, silver nanowires, and silver nanoparticles; the hydrophilic polymer is one or more of sodium polyacrylate, polyvinyl alcohol, and polyethylene glycol; the hydrophilic solvent is water, ethanol, or isopropanol; the concentration of the hydrophilic conductive material in the composite conductive spinning solution is 0.1-20 wt%, and the concentration of the hydrophilic polymer in the composite conductive spinning solution is 0.01-5 wt%. S3. Using a wet spinning method, the perovskite polymer composite spinning solution obtained in step S1 is extruded into a coagulation bath to initially solidify into fibers, obtaining a core layer. Before the core layer is completely solidified and dried, it is quickly immersed in the composite conductive spinning solution obtained in step S2, so that the core layer is fully and uniformly coated with a conductive layer, obtaining a composite fiber filament. Then, heat treatment is performed to dry and solidify the composite fiber filament and further crystallize the core layer material. After natural cooling, a visual multifunctional humidity-strain sensor with a core-skin structure is obtained.

2. The method for fabricating a visual multifunctional humidity-strain sensor according to claim 1, characterized in that, In step S1, the solvent of the polymer solution is one or a mixture of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and γ-butyrolactone.

3. The method for fabricating a visual multifunctional humidity-strain sensor according to claim 1, characterized in that, In step S3, the coagulation bath is water at room temperature, and the heat treatment temperature is lower than or equal to 180°C.

4. A visual multifunctional humidity-strain sensor, characterized in that, The visualized multifunctional humidity-strain sensor is prepared by the method according to any one of claims 1-3. The visualized multifunctional humidity-strain sensor has a core-skin structure. The core layer is a composite fluorescent elastic material prepared by perovskite and polymer, and the skin layer is a composite conductive material prepared by water-based conductive material and hydrophilic polymer. The skin layer is a humidity-strain sensing layer. The visualized multifunctional humidity-strain sensor has photoluminescence properties, and the fluorescence emitted by the core layer under ultraviolet light irradiation penetrates the skin layer structure, making the fluorescence of the visualized multifunctional humidity-strain sensor visible.

5. The visualized multifunctional humidity-strain sensor according to claim 4, characterized in that, The photoluminescence color of the visualized multifunctional humidity-strain sensor is controlled by changing the type and proportion of X element contained in the core layer; the photoluminescence fluorescence intensity of the visualized multifunctional humidity-strain sensor decreases by less than 5% after being stored in air with constant temperature and humidity for 30 days; and the photoluminescence fluorescence intensity decreases by less than 5% after the visualized multifunctional humidity-strain sensor is repeatedly stretched to a length deformation of 200% for 1000 cycles.

6. The visualized multifunctional humidity-strain sensor according to claim 4, characterized in that, The resistance of the visualized multifunctional humidity-strain sensor is adjusted by changing the proportion of conductive material in the cortex, and the resistance adjustment range is between 100Ω and 1MΩ. The normalized resistance change rate of the visualized multifunctional humidity-strain sensor in an environment with a humidity of 23-95%RH is greater than or equal to 120%. The normalized resistance change rate of the visualized multifunctional humidity-strain sensor is less than 10% after being stored in air with constant temperature and humidity for 24 days. The normalized resistance change rate of the visualized multifunctional humidity-strain sensor is less than 10% when the storage temperature is increased from 15℃ to 45℃.

7. The application of a visual multifunctional humidity-strain sensor prepared by the method of any one of claims 1-3, or a visual multifunctional humidity-strain sensor prepared by any one of claims 4-6, characterized in that, The visualized multifunctional humidity-strain sensor is used to monitor human physiological activities, display flexible patterns, provide encryption and anti-counterfeiting features, detect skin humidity, act as a non-contact switch, and provide hazard warnings.

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