Flexible functionalized eggshell membrane, method of making and use thereof
By preparing a flexible functionalized eggshell membrane ESM-PDA@rGO, combined with reduced graphene oxide and polydopamine, the shortcomings of existing thermometers in terms of accuracy, response time and comfort are solved, realizing rapid, accurate, stable and breathable body temperature monitoring using a flexible temperature sensor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-20
- Publication Date
- 2026-03-24
AI Technical Summary
Existing thermometers are inadequate in terms of accuracy, response time, and comfort, failing to meet the needs for long-term accurate monitoring and comfortable wear, especially for non-flexible wearable thermometers.
A flexible functionalized eggshell membrane ESM-PDA@rGO was used to prepare a flexible temperature sensor by combining reduced graphene oxide rGO with eggshell membrane and polydopamine PDA. The sensor’s conductivity and stability were enhanced by utilizing the three-dimensional protein fiber network microstructure of the eggshell membrane and the high thermal conductivity of reduced graphene oxide, combined with the self-polymerization effect of dopamine.
It achieves rapid response, high accuracy, good bending stability, and excellent breathability and antibacterial properties, making it suitable for long-term comfortable wear and enabling continuous and accurate monitoring of body temperature.
Smart Images
Figure CN116754087B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of flexible temperature sensor, and particularly relates to a flexible functionalized eggshell membrane as well as a preparation method and application thereof. BACKGROUND
[0002] Body temperature is one of the most important physiological parameters of human body, and maintaining body temperature in a normal range is a necessary condition for ensuring normal metabolism and life activities of human body. Therefore, accurate and long-term monitoring of body temperature is of great significance for health monitoring and early warning intervention of cardiovascular and cerebrovascular diseases.
[0003] At present, commonly used thermometers include mercury thermometer, electronic thermometer and infrared thermometer, etc. Among them, although the mercury thermometer has high accuracy, it is inconvenient to use for special objects such as newborns; and the accuracy of the electronic thermometer is affected by electronic components, battery power supply conditions and surrounding environment, etc. Not only the measurement stability is poor, but also the measurement range is limited, generally only in 32-42℃; the infrared thermometer has fast response time, but its accuracy is poor and is easily disturbed by external interference. In addition, since these thermometers are non-flexible wearable, they cannot meet the needs of long-term monitoring of body temperature in a flexible and comfortable manner. In summary, there is an urgent need to develop a flexible thermometer with fast response time, high accuracy and long-term comfortable wearing. SUMMARY
[0004] The present application aims to provide a flexible functionalized eggshell membrane as well as a preparation method and application thereof, so as to solve the problems that the existing thermometers cannot meet the requirements of long-term accurate monitoring and comfortable wearing, etc.
[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:
[0006] One aspect of the present application is to provide a preparation method of a flexible functionalized eggshell membrane, comprising: S1, preparing reduced graphene oxide rGO: dispersing graphene oxide GO in deionized water to form a graphene oxide GO dispersion, adding sodium borohydride as a reducing agent, reducing at 60-70 DEG C for 30-60 min, and centrifuging to obtain reduced graphene oxide nanometer powder rGO; S2, pretreating eggshell membrane ESM: rinsing the eggshell ES clean, ultrasonicating in white vinegar at room temperature for 30-40 min, peeling off the eggshell membrane ESM, and rinsing with ultrapure water to remove residual substances, then ultrasonicating the eggshell membrane ESM in sodium hydroxide at room temperature for 30-60 min, and rinsing with deionized water to obtain the pretreated eggshell membrane ESM; S3, preparing a polydopamine PDA precursor solution: adding dopamine DA to Tris buffer and fully oscillating for 30-50 min to obtain the polydopamine PDA precursor solution; S4, preparing a flexible functionalized eggshell membrane ESM-PDA@rGO: adding the pretreated eggshell membrane ESM and the reduced graphene oxide rGO nanometer powder to the polydopamine PDA precursor solution, and constant-temperature oscillating polymerization at 35-37 DEG C for 24-48 h to obtain the flexible functionalized eggshell membrane ESM-PDA@rGO.
[0007] In the present application, the order of steps S1, S2 and S3 is not limited.
[0008] In the present application, the flexible functionalized eggshell membrane ESM-PDA@rGO is a flexible membrane.
[0009] Optionally, in step S1, the concentration of the graphene oxide GO dispersion is 1-2 mg / mL, and the mass ratio of sodium borohydride to graphene oxide GO is (10-20):(20-40).
[0010] Optionally, in step S2, the concentration of sodium hydroxide is 0.5-1 M.
[0011] Optionally, in step S3, the ratio of tris to water in the Tris buffer is (2420-4840) mg:(20-40) mL, and the ratio of DA to Tris buffer in the polydopamine PDA precursor solution is (40-80) mg:(20-40) mL.
[0012] Optionally, in step S4, the ratio of the eggshell membrane ESM, the reduced graphene oxide rGO nanometer powder and the polydopamine PDA precursor solution is (2-5) pieces:(20-40) mg:(20-40) mL.
[0013] The second aspect of the present application provides a flexible functionalized eggshell membrane ESM-PDA@rGO obtained by the preparation method.
[0014] The third aspect of the present application provides a temperature sensor comprising the flexible functionalized eggshell membrane ESM-PDA@rGO.
[0015] In the present application, the temperature sensor is a flexible temperature sensor.
[0016] Optionally, the temperature sensor comprises an upper packaging layer, a lower packaging layer, a temperature sensitive layer packaged between the upper packaging layer and the lower packaging layer, and a lead wire connected to the temperature sensitive layer; the temperature sensitive layer is obtained by mechanical pressing of the flexible functionalized eggshell membrane ESM-PDA@rGO; and the lead wire comprises a flexible carbon fiber.
[0017] Optionally, two flexible carbon fiber lead wires can be fixed at both ends of the temperature sensitive layer with the aid of conductive silver paste, and then the temperature sensitive layer is packaged through the upper packaging layer and the lower packaging layer, thereby obtaining the temperature sensor.
[0018] Optionally, the upper packaging layer and the lower packaging layer are both 3M breathable adhesive tape packaging layers.
[0019] Optionally, the temperature sensitive layer is obtained by mechanical pressing of at least one layer of the flexible functionalized eggshell membrane ESM-PDA@rGO.
[0020] Optionally, the temperature sensitive layer is obtained by mechanical pressing of 1-4 layers of the flexible functionalized eggshell membrane ESM-PDA@rGO.
[0021] In the present application, the temperature sensitive layer has strong shape adaptability and can be cut to shape according to the actual application site and / or cut to a shape compatible with wearable products such as earphones, earplugs, masks, etc.
[0022] The fourth aspect of the present application provides an application of the temperature sensor to a wearable thermometer.
[0023] In the present application, the wearable thermometer is a flexible thermometer that can be worn on the surface of human skin and is not affected by bending deformation, sweat, etc., and has excellent wearing stability.
[0024] Optionally, the wearable thermometer can be arbitrarily cut according to the wearing site.
[0025] Optionally, the wearable thermometer can be cut into a shape of a circle, a square, a rectangle, or a pentagon, etc.
[0026] Optionally, the wearable thermometer can have the same shape as the temperature sensor.
[0027] Optionally, the temperature sensor can have the same shape as the temperature sensitive layer.
[0028] Optionally, the temperature sensitive layer can be cut according to the temperature measuring site.
[0029] Compared with the prior art, the technical scheme of the present application has beneficial effects.
[0030] 1、The present application is based on the excellent flexibility, air permeability and good thermal stability of eggshell membrane, utilizes the self-polymerization effect of dopamine molecules, combines the high thermal conductivity and negative temperature coefficient of reduced graphene nanomaterials, functionalizes the natural eggshell membrane, and develops a flexible functionalized eggshell membrane temperature sensitive material, the mechanical properties of the flexible functionalized eggshell membrane temperature sensitive material are significantly enhanced, and the flexible functionalized eggshell membrane temperature sensitive material has excellent temperature sensitive characteristics, a negative temperature coefficient, rapid responsiveness, bending resistance stability, air permeability, antibacterial property and comfortable flexible wearability, can be widely applied to flexible temperature sensors and wearable thermometers, and can realize continuous, accurate and rapid monitoring of body temperature.
[0031] 2、The present application takes natural eggshell membrane as a flexible substrate, since the eggshell membrane is a biological protein membrane with a unique three-dimensional protein fiber network microstructure, it has high porosity and good permeability, can eliminate the influence of the directionality of heat conduction on temperature sensing, the randomly arranged fiber network structure can also ensure the isotropy of temperature sensing, in addition, it can also provide rich binding sites for the combination of polydopamine and reduced graphene oxide.
[0032] 3、The application organically combines the eggshell membrane and the reduced graphene oxide through the biological self-assembly process of oxidative polymerization of dopamine, wherein the polydopamine combines the eggshell membrane and the reduced graphene oxide through the combination of H bonds and hydroxyl amino groups and the interaction of pi-pi bonds, and the random length and angle of the polydopamine chain can also make the reduced graphene oxide multilayer and disorderly distributed along the morphology of the eggshell membrane, and the polydopamine also establishes a conductive path in the process of combining the eggshell membrane and the reduced graphene oxide through chemical bonds, reduces the carrier transport barrier, and thus improves the conductivity of the sensing film, which also makes the conductive path established by the reduced graphene oxide not be damaged due to the slip of the reduced graphene oxide nanosheet, so that the conductive path of the temperature sensor always remains complete, and thus the stability of the thermometer is maintained well.
[0033] 4、The flexible temperature sensor prepared in the application has good continuous stability, can guarantee the stability of the sensor in the bending condition, and thus can guarantee the accuracy of the wearable thermometer in the long-term wearing process.
[0034] 5、The raw materials used in the application are all biodegradable materials, which are easy to obtain, and the functionalized eggshell membrane and the preparation method of the sensor are simple, and are suitable for batch popularization and application.
[0035] 6、Generally, eggshell membranes are discarded as daily waste, and the application functionalizes and converts the eggshell membranes into high-value products for reuse, greatly improves the utilization value of the discarded eggshell membranes, and is beneficial to green environmental protection and sustainable development. BRIEF DESCRIPTION OF DRAWINGS
[0036] Figure 1 The structural schematic diagram, shape schematic diagram and application schematic diagram in human body temperature measurement of the wearable thermometer provided for the embodiment 1 of the application are shown, wherein (a) is the structural schematic diagram, (b) is the shape schematic diagram, and (c) is the application schematic diagram in the human body temperature measurement;
[0037] Figure 2 The SEM diagrams of the eggshell membrane ESM provided for the comparative example and the flexible functionalized eggshell membrane ESM-PDA@rGO provided for the embodiment 1 of the application are shown, wherein (a) is the SEM diagram of the eggshell membrane ESM provided for the comparative example, and (b) is the SEM diagram of the flexible functionalized eggshell membrane ESM-PDA@rGO provided for the embodiment 1 of the application;
[0038] Figure 3 The resistance-temperature response curve, resolution, resistance-time response time curve and continuous stability of the wearable thermometer provided for the embodiment 1 of the application are shown, wherein (a) is the resistance-temperature response curve, (b) is the resolution, (c) is the resistance-time response time curve, and (d) is the continuous stability;
[0039] Figure 4 The resistance-temperature response curves of the temperature sensor provided in Embodiment 2 and the comparative example of the present invention are shown.
[0040] Figure 5 The resistance-temperature response curves of temperature sensors of different shapes provided in Embodiment 3 of the present invention are shown.
[0041] Figure 6 The resistance-time response curve of the temperature sensor provided as a comparative example of the present invention;
[0042] Figure 7 Cyclic stability test results of the temperature sensor provided as a comparative example of the present invention and the wearable thermometer provided in Example 1;
[0043] Figure 8 The results of the air permeability test of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Embodiment 1 of the present invention;
[0044] Figure 9 The antibacterial test results are for the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Embodiment 1 of the present invention and the non-functionalized eggshell membrane ESM provided in the comparative example.
[0045] Figure 10 The bending stability test results of the wearable thermometer provided in Embodiment 1 of the present invention;
[0046] Figure 11 The following is a specific application of the wearable thermometer provided in Embodiment 1 of the present invention and a comparison with the stress-strain curve of the comparative example, wherein (a) is a specific application scenario of the wearable thermometer and (b) is a stress-strain curve.
[0047] Figure 12 The wearable thermometer provided in Embodiment 1 of the present invention provides a temperature-time response curve and a temperature-time scatter plot for body temperature monitoring; wherein, (a) is a temperature-time response curve of forehead temperature of a healthy male, and (b) is a temperature-time scatter plot of palm temperature monitoring of a healthy male for 12 consecutive hours. Detailed Implementation
[0048] To make the objectives, features, and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described below are merely illustrative of the present invention and not intended to limit the scope of the invention.
[0049] Example 1
[0050] This embodiment first provides a flexible functionalized eggshell membrane ESM-PDA@rGO.
[0051] The preparation process of the flexible functionalized eggshell membrane ESM-PDA@rGO is as follows:
[0052] S11, preparation of reduced graphene oxide rGO:
[0053] 20 mg of graphene oxide GO was weighed and dispersed in 20 mL of deionized water, 10 mg of sodium borohydride was added, and the reduction was carried out at 70°C in a water bath for 30 min to obtain a reduced graphene oxide rGO solution. After centrifugation, reduced graphene oxide rGO nanopowder was obtained;
[0054] S12, pretreatment of eggshell membrane ESM:
[0055] The eggshell ESM was washed with water to remove residual protein, then placed in white vinegar at room temperature for ultrasonic treatment for 30 min, and the eggshell membrane ESM was peeled off and washed with ultrapure water for 3 times to remove residual substances, then placed in 0.5M sodium hydroxide solution for ultrasonic treatment for 40 min, and then rinsed with deionized water to obtain pretreated eggshell membrane ESM for standby;
[0056] S13, preparation of polydopamine PDA precursor solution:
[0057] 3630 mg of Tris was added to 30 mL of deionized water, and the mixture was shaken until completely dissolved. Then 60 mg of dopamine DA was added, and the mixture was shaken for 40 min to obtain a polydopamine PDA precursor solution;
[0058] In this embodiment, the order of steps S11, S12 and S13 is not limited.
[0059] S14, preparation of flexible functionalized eggshell membrane ESM-PDA@rGO:
[0060] The pretreated 4 pieces of eggshell membrane ESM and reduced graphene oxide rGO nanopowder were added to the polydopamine PDA precursor solution, and the mixture was placed in a 37°C constant temperature oscillator for polymerization for 24 h to obtain a flexible functionalized eggshell membrane ESM-PDA@rGO.
[0061] The embodiment also provides a flexible temperature sensor comprising the flexible functionalized eggshell membrane ESM-PDA@rGO provided by the embodiment.
[0062] The flexible temperature sensor comprises an upper packaging layer, a lower packaging layer, a temperature-sensitive layer packaged between the upper packaging layer and the lower packaging layer, and a lead wire connected to the temperature-sensitive layer. The temperature-sensitive layer is obtained by mechanically pressing 4 layers of the flexible functionalized eggshell membrane ESM-PDA@rGO provided by the embodiment; and the lead wire comprises a flexible carbon fiber.
[0063] Specifically, the preparation method of the temperature-sensitive layer comprises:
[0064] Take 4 pieces of flexible functionalized eggshell membrane ESM-PDA@rGO and mechanically compress them into a sheet. Then cut them into 1cm x 1cm squares to obtain a temperature-sensitive layer with a thickness of 0.29mm.
[0065] Specifically, the preparation method of the flexible temperature sensor comprises:
[0066] Two flexible carbon fiber leads are fixed at both ends of the temperature-sensitive layer with the aid of conductive silver paste. Then, the temperature-sensitive layer is packaged with two 2cm x 1.8cm 3M breathable adhesive tapes from top to bottom, and the flexible temperature sensor is obtained.
[0067] The embodiment also provides an application of the flexible temperature sensor to a wearable thermometer.
[0068] Embodiment 2
[0069] The embodiment first provides a flexible functionalized eggshell membrane ESM-PDA@rGO.
[0070] The preparation process of the flexible functionalized eggshell membrane ESM-PDA@rGO is as follows:
[0071] S21, preparation of reduced graphene oxide rGO:
[0072] Weigh 40mg of graphene oxide GO and disperse it in 20mL of deionized water. Add 20mg of sodium borohydride and reduce at 65℃ in a water bath for 40min to obtain a reduced graphene oxide rGO solution. After centrifugation, we obtain reduced graphene oxide rGO nanopowder;
[0073] S22, pretreatment of eggshell membrane ESM:
[0074] Rinse the eggshell ES with water to remove residual proteins, then place it in white vinegar at room temperature and ultrasonic for 40min. Peel off the eggshell membrane ESM and wash it with ultrapure water for 3 times. After removing the residual substances, place it in 0.7M sodium hydroxide solution and ultrasonic for 50min. Rinse with deionized water to obtain pretreated eggshell membrane ESM for standby;
[0075] S23, preparation of polydopamine PDA precursor solution:
[0076] Add 4840mg of Tris to 40mL of deionized water and shake well until completely dissolved. Then add 80mg of dopamine DA and shake for 60min to obtain a polydopamine PDA precursor solution;
[0077] In this embodiment, the order of steps S21, S22 and S23 is not limited.
[0078] S24, preparing flexible functionalized eggshell membrane ESM-PDA@rGO:
[0079] The pretreated 2 pieces of eggshell membrane ESM and reduced graphene oxide rGO nano powder were added into a polydopamine PDA precursor solution, and were put into a 36℃ constant temperature oscillator for polymerization for 36h to obtain the flexible functionalized eggshell membrane ESM-PDA@rGO.
[0080] The embodiment also provides a flexible temperature sensor comprising the flexible functionalized eggshell membrane ESM-PDA@rGO provided by the embodiment.
[0081] The flexible temperature sensor comprises an upper packaging layer, a lower packaging layer, a temperature sensitive layer packaged between the upper packaging layer and the lower packaging layer, and a lead wire connected with the temperature sensitive layer. The temperature sensitive layer is composed of 1 layer of the flexible functionalized eggshell membrane ESM-PDA@rGO provided by the embodiment; and the lead wire comprises a flexible carbon fiber.
[0082] Specifically, the preparation method of the temperature sensitive layer comprises:
[0083] 1 piece of the flexible functionalized eggshell membrane ESM-PDA@rGO was cut into a 1cm×1cm square to obtain 1 layer of the temperature sensitive layer.
[0084] Specifically, the preparation method of the flexible temperature sensor comprises:
[0085] Two flexible carbon fiber lead wires were fixed at two ends of the temperature sensitive layer with the aid of conductive silver paste, and then the temperature sensitive layer was packaged with two 2cm×1.8cm 3M breathable adhesive tapes from top to bottom, so as to obtain the flexible temperature sensor.
[0086] The embodiment also provides an application of the flexible temperature sensor to a wearable thermometer.
[0087] Embodiment 3
[0088] The embodiment first provides a flexible functionalized eggshell membrane ESM-PDA@rGO.
[0089] The preparation process of the flexible functionalized eggshell membrane ESM-PDA@rGO is as follows:
[0090] S31, preparing reduced graphene oxide rGO:
[0091] 30mg of graphene oxide GO was weighed and dispersed in 20mL of deionized water, 15mg of sodium borohydride was added, and the mixture was reduced at 60℃ in a water bath for 60min to obtain a reduced graphene oxide rGO solution. After centrifugation, reduced graphene oxide rGO nano powder was obtained;
[0092] S32, pretreating eggshell membrane ESM:
[0093] The eggshell ES is rinsed with clean water to remove residual egg white, then placed in white vinegar at room temperature for 35 min of ultrasonic, the eggshell membrane ESM is stripped, and washed with ultrapure water for 3 times, and then placed in 1M sodium hydroxide solution for 30 min of ultrasonic, and then rinsed with deionized water to obtain pretreated eggshell membrane ESM for standby;
[0094] S33, preparing a polydopamine PDA precursor solution:
[0095] Add 2420 mg of Tris to 20 mL of deionized water, shake well until completely dissolved, then add 40 mg of dopamine DA, shake for 30 min to obtain a polydopamine PDA precursor solution;
[0096] In this embodiment, the order of steps S31, S32 and S33 is not limited.
[0097] S34, preparing a flexible functionalized eggshell membrane ESM-PDA@rGO:
[0098] Add the pretreated 5 pieces of eggshell membrane ESM and reduced graphene oxide rGO nano powder to the polydopamine PDA precursor solution, and place it in a 35°C constant temperature oscillator for polymerization for 48 h to obtain a flexible functionalized eggshell membrane ESM-PDA@rGO.
[0099] The present embodiment also provides a flexible temperature sensor comprising the flexible functionalized eggshell membrane ESM-PDA@rGO provided by the present embodiment.
[0100] The flexible temperature sensor comprises an upper packaging layer, a lower packaging layer, a temperature sensitive layer packaged between the upper packaging layer and the lower packaging layer, and a lead wire connected to the temperature sensitive layer. The temperature sensitive layer is composed of 3 layers of flexible functionalized eggshell membrane ESM-PDA@rGO mechanically pressed by the present embodiment. The lead wire comprises a flexible carbon fiber.
[0101] Specifically, the preparation method of the temperature sensitive layer comprises:
[0102] Mechanically press 3 pieces of flexible functionalized eggshell membrane ESM-PDA@rGO to obtain 3 layers of flexible functionalized eggshell membrane, and then cut it into squares, rectangles and / or circles with the same area (1 cm 2 ) to obtain temperature sensitive layers of different shapes.
[0103] Specifically, the preparation method of the flexible temperature sensor comprises:
[0104] Two flexible carbon fiber lead wires are fixed at both ends of the temperature sensitive layer by conductive silver paste, and then the temperature sensitive layer is encapsulated by two 2cm*1.8cm 3M breathable adhesive tapes, to obtain the flexible temperature sensor.
[0105] The embodiment also provides an application of the flexible temperature sensor to a wearable thermometer.
[0106] Comparative Example
[0107] The comparative example provides a flexible temperature sensor and an application of the flexible temperature sensor to a wearable thermometer.
[0108] The comparative example differs from the embodiment 1 in that a natural and non-functionalized eggshell membrane ESM is used to prepare the temperature sensitive layer in the flexible temperature sensor.
[0109] Structure, application and performance test
[0110] Figure 1 The structure schematic diagram, shape schematic diagram and application schematic diagram of the wearable thermometer provided in the embodiment 1 in human body temperature measurement are shown in (a), (b) and (c).
[0111] Reference Figure 1 As shown in (a), the wearable thermometer prepared in the present application comprises a three-layer structure, specifically comprising an upper encapsulation layer 1, a temperature sensitive layer 2, a lower encapsulation layer 3 and a lead wire 4.
[0112] Reference Figure 1 As shown in (b), in specific implementation, the shape of the wearable thermometer prepared in the present application can be freely and arbitrarily cut. For example, a triangle, a five-pointed star, a heart shape or a square shape can be cut.
[0113] Reference Figure 1 As shown in (c), the wearable thermometer prepared in the present application can be worn at a position where temperature measurement is needed, for example, the forehead, the temple, the cochlea close to the body core, and the palm, the back of the hand and the back of the foot close to the body surface. In specific implementation, the resistance change of the wearable thermometer can be used to calculate the size of the measured temperature.
[0114] The structure, shape and application of the wearable thermometer provided in the embodiment 2 and the embodiment 3 in human body temperature measurement are similar to those of the embodiment 1.
[0115] Figure 2SEM images of the eggshell membrane ESM provided for the comparative example of the present application and the flexible functionalized eggshell membrane ESM-PDA@rGO provided for Example 1, wherein (a) is the SEM image of the eggshell membrane ESM provided for the comparative example, and (b) is the SEM image of the flexible functionalized eggshell membrane ESM-PDA@rGO provided for Example 1.
[0116] Referring to Figure 2 It can be seen that the eggshell membrane ESM in the comparative example is a three-dimensional porous fiber network structure, and the fiber surface is smooth; while the flexible functionalized eggshell membrane ESM-PDA@rGO provided for Example 1, after the biological self-assembly with dopamine DA and reduced graphene oxide rGO, the fiber surface becomes rough. This shows that the reduced graphene oxide rGO has been successfully assembled on the eggshell membrane ESM fiber, that is, the functionalized eggshell membrane ESM-PDA@rGO is successfully prepared. Dopamine DA is connected to the eggshell membrane ESM through H bonds in the process of oxidative polymerization, and is connected to the reduced graphene oxide rGO through π-π bonds, thereby assembling the reduced graphene oxide rGO on the fiber surface of the eggshell membrane ESM. In addition, the polyl dopamine establishes a conductive path between the graphenes in this process, making the conductive path established by a single graphene material more stable. This makes the flexible wearable thermometer prepared from the functionalized eggshell membrane of the present application not only have good air permeability and antibacterial property, but also have high sensitivity to temperature sensing and good stability, realizing the high-value utilization of the eggshell membrane waste biomass resource, and providing a beneficial method for human health monitoring.
[0117] The morphology of the flexible functionalized eggshell membrane ESM-PDA@rGO provided for Example 2 and Example 3 and the performance brought by the morphology are similar to those of Example 1.
[0118] Figure 3 The resistance-temperature response curve, resolution, resistance-time response time curve and continuous stability of the wearable thermometer provided for Example 1 of the present application, wherein (a) is the resistance-temperature response curve, (b) is the resolution, (c) is the resistance-time response time curve, and (d) is the continuous stability.
[0119] Referring to Figure 3(a), is a response curve of resistance of the wearable thermometer with temperature, wherein the abscissa is temperature, unit: ℃, and the ordinate is the percentage of real-time resistance change ΔR and initial resistance R0. As can be seen from the figure, the flexible wearable thermometer provided by the application shows a negative temperature coefficient in the temperature range of 15-80℃, that is, the resistance decreases with the increase of temperature. Thus, it is illustrated that the wearable thermometer prepared by the application has a wide temperature response range and good linearity in the physiological temperature range. On the one hand, the negative temperature coefficient is a characteristic of reduced graphene oxide rGO material, and the thermal non-expansion of eggshell membrane ESM ensures that the distance between the reduced graphene oxide rGO materials will not increase due to the heating of the substrate, thereby causing the resistance to increase. On the other hand, the polydopamine connects the reduced graphene oxide rGO through π-π bond to form a more stable conductive and heat-conductive path, which ensures the stable connection of the conductive path during the heating-cooling process.
[0120] Referring to Figure 3 (b), is a resolution curve of the wearable thermometer, wherein the abscissa is temperature, unit: ℃, and the ordinate is the percentage of real-time resistance change ΔR and initial resistance R0, and the temperature measurement range is 36-38℃ (which can cover the daily body temperature of a healthy human body). As can be seen from the figure, the flexible wearable thermometer provided by the application shows a resolution of 0.1℃ in the human body temperature range. Thus, it is illustrated that the wearable thermometer prepared by the application has high accuracy and can meet the accuracy requirements of monitoring human body temperature.
[0121] Referring to Figure 3 (c), is a response curve of resistance of the wearable thermometer with time, wherein the abscissa is time, unit: s, and the ordinate is the percentage of real-time resistance change ΔR and initial resistance R0. As can be seen from the figure, the flexible wearable thermometer provided by the application has a response time of 8s at 30-40℃. Thus, it is illustrated that the wearable thermometer prepared by the application has a fast response time for temperature monitoring in the physiological temperature range, compared with commonly used mercury thermometers, which saves a lot of detection time for the subjects. This is because the reduced graphene oxide rGO and the polydopamine PDA form a high-thermal-conductivity network, and the overall thickness of the temperature-sensitive layer is only 0.29mm, so the heat conduction speed is fast.
[0122] Referring to Figure 3(d) is a curve diagram of the continuous stability of the wearable thermometer, wherein the abscissa is time, s, and the ordinate is the ratio of the real-time resistance R and the initial resistance R0. As can be seen from the figure, the flexible wearable thermometer provided by the application shows good continuous stability within 300 s at 25℃, 30℃, 35℃, 40℃ and 45℃, respectively, and the standard deviation (SD) of each group of response values is less than 0.007, that is, the response value of the thermometer to temperature fluctuates less within 300 s of continuous time, close to the mean value. Thus, the wearable thermometer prepared by the application has excellent continuous stability and shows long-term monitoring application potential. This is because the polydopamine PDA successfully assembles the reduced graphene oxide rGO and the eggshell membrane ESM through H bonds and π-π bonds, and establishes a continuous conductive path in the process, ensuring the stability during monitoring.
[0123] The resistance-temperature response curve, resolution, resistance-time response time curve, continuous stability and performance embodied by the wearable thermometer provided by example 2 and example 3 are similar to those of example 1.
[0124] Figure 4 The resistance-temperature response curve of the temperature sensor provided by example 2 and comparative example of the application.
[0125] Referring to Figure 4 The resistance-temperature response curve of the temperature sensor provided by example 2 and comparative example of the application.
[0126] Figure 5 The resistance-temperature response curve of the temperature sensor provided by example 2 and comparative example of the application.
[0127] Referring to Figure 5The resistance-temperature response curve of the temperature sensor provided by the embodiment 3 of the present application in the range of 30-42℃ is shown in the figure. In the figure, the abscissa represents temperature in ℃, and the ordinate represents the percentage of the real-time resistance change ΔR and the initial resistance R0. It can be seen from the figure that the response curves of the temperature sensors with different shapes such as circle, square and rectangle provided by the embodiment of the present application are almost coincident in this temperature range. Therefore, the functionalized eggshell membrane ESM-PDA@rGO provided by the present application can be trimmed into any shape to make a thermometer suitable for the shape of various detection sites. This is because the eggshell membrane ESM has high porosity and good permeability, which can eliminate the influence of the directionality of heat conduction on temperature sensing, and the randomly arranged fibrous network structure can also ensure the isotropy of temperature sensing.
[0128] Figure 6 The resistance-time response curve of the temperature sensor provided by the comparative example of the present application.
[0129] Referring to Figure 6 The resistance-time response curve of the temperature sensor provided by the comparative example of the present application. In the figure, the abscissa represents time in s, and the ordinate represents the ratio of the real-time resistance R and the initial resistance R0. It can be seen from the figure that the response time of the temperature sensor prepared by the eggshell membrane ESM provided by the comparative example is 30 s, while the response time of the thermometer prepared by the functionalized eggshell membrane ESM-PDA@rGO provided by the present application is 8 s. Figure 3 (c) It can be seen that the response time of the thermometer prepared by the functionalized eggshell membrane ESM-PDA@rGO provided by the present application is 8 s, which is much smaller than that of the comparative example. Therefore, the response speed of the thermometer prepared by the functionalized eggshell membrane ESM-PDA@rGO provided by the present application is very fast.
[0130] While the response time of the commercial mercury thermometer is usually 5-8 minutes, which is much larger than the response time of the thermometer prepared by the functionalized eggshell membrane ESM-PDA@rGO provided by the present application.
[0131] Figure 7 The cycle stability test results of the temperature sensor provided by the comparative example of the present application and the wearable thermometer provided by the embodiment 1.
[0132] Referring to Figure 7 The comparison of the cycle stability test results of the temperature sensor provided by the comparative example of the present application and the wearable thermometer provided by the embodiment 1 in the range of 30-40℃. In the figure, the abscissa represents time in s, and the ordinate represents the percentage of the real-time resistance change ΔR and the initial resistance R0. It can be seen from the figure that the stability of the temperature sensor provided by the comparative example is poor, and its response value is much smaller than that of the thermometer prepared by the functionalized eggshell membrane ESM-PDA@rGO provided by the present application.
[0133] The results of the cycle stability test of the wearable thermometer provided in Example 2 and Example 3 are similar to those of Example 1.
[0134] Figure 8 The results of the air permeability test of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Example 1.
[0135] Referring to Figure 8 The results of the air permeability test of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Example 1. The vertical coordinate is the water vapor transmission rate WVT, with the unit of mg / cm 2 , and the horizontal coordinate is time, with the unit of h. In a specific implementation, a flexible functionalized eggshell membrane ESM-PDA@rGO with a size of 2 cm x 2 cm is covered on the mouth of a glass bottle containing deionized water (the mouth area A = 1.24 cm 2 ), and the mass is denoted as M0, and placed in an environment with a temperature of 37℃ and a humidity of 75% for 24 h. The mass M t (t = 2, 4, 8, 16, and 24) is recorded respectively. As can be seen from the figure, the WVTR value of the flexible functionalized eggshell membrane ESM-PDA@rGO reaches 14.6 mg / cm 2 ·h, which is much larger than the sweat amount of 3 mg / cm 2 ·h of a hyperhidrosis person. Therefore, the flexible functionalized eggshell membrane ESM-PDA@rGO provided in the present application has good air permeability, which can ensure the comfort of long-term wearing. This is because the eggshell membrane ESM has a unique three-dimensional protein fiber network microstructure, which has high porosity and good permeability, which is also the guarantee of the air permeability of the wearable thermometer prepared.
[0136] In a specific implementation, the WVTR is calculated by the following formula:
[0137] WVTR = (M0-M t ) / (A·t) x 100%.
[0138] The air permeability of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Example 2 and Example 3 is similar to that of Example 1.
[0139] Figure 9 The results of the antibacterial test of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Example 1 and the non-functionalized eggshell membrane ESM provided in the comparative example.
[0140] Referring to Figure 9The antibacterial test results of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Example 1 of the present application and the non-functionalized eggshell membrane ESM provided in the comparative example. Among them, the white circle corresponds to the non-functionalized eggshell membrane ESM provided in the comparative example, and the black circle corresponds to the flexible functionalized eggshell membrane ESM-PDA@rGO. As can be seen from the figure, the flexible functionalized eggshell membrane ESM-PDA@rGO provided in the present application shows obvious antibacterial properties to P. aeruginosa and S. aureus, and the antibacterial diameter to P. aeruginosa is 17.3 mm, and the antibacterial diameter to S. aureus is 11.1 mm. While in the control group, the non-functionalized eggshell membrane ESM provided in the comparative example hardly shows an antibacterial ring.
[0141] The antibacterial performance of the flexible functionalized eggshell membrane ESM-PDA@rGO provided in Examples 2 and 3 is similar to that of Example 1.
[0142] Figure 10 The bending stability test results of the flexible wearable thermometer provided in Example 1 of the present application.
[0143] Referring to Figure 10 The resistance change of the flexible wearable thermometer provided in the present application under different bending angles, wherein the abscissa is the bending angle θ, the unit is °, and the ordinate is the resistance R, the unit is kΩ. As can be seen from the figure, with the increase of the bending angle, the resistance of the flexible wearable thermometer provided in the present application remains almost unchanged, which is 1.57 kΩ. Therefore, it is illustrated that the flexible wearable thermometer provided in the present application is not affected by the bending deformation, and can meet the requirement of wearing stability.
[0144] The bending stability performance of the flexible wearable thermometer provided in Examples 2 and 3 is similar to that of Example 1.
[0145] Figure 11 The specific application of the wearable thermometer provided in Example 1 of the present application and the stress-strain curve comparison with the comparative example, wherein (a) is the specific application scene of the wearable thermometer, and (b) is the stress-strain curve.
[0146] Referring to Figure 11 (a), the specific application scene of the wearable thermometer provided in Example 1 of the present application. Specifically, the wearable thermometer can be applied to Bluetooth earphones and noise-proof earplugs. In specific implementation, the wearable thermometer can be attached to the Bluetooth earphones and noise-proof earplugs for real-time monitoring of human cochlea temperature and reducing environmental interference; at the same time, the figure also shows that the wearable thermometer has flexible twistable performance.
[0147] Referring to Figure 11(b), compared with the comparative example, the wearable thermometer provided by the embodiment 1 of the present application has obvious improvement in tensile mechanical properties. Specifically, compared with the comparative example, the elongation at break of the wearable thermometer provided by the embodiment 1 of the present application is increased from 44.16% to 60.75%, and the Young's modulus is also increased from 3.66 MPa to 6.44 MPa. Since the higher the elongation and the Young's modulus, the more stress deformation the material can withstand, the better the toughness, that is, the mechanical resistance of the wearable thermometer can be improved. Therefore, compared with the thermometer of the comparative example, the wearable thermometer provided by the embodiment 1 of the present application is more in line with the deformation of human skin during long-term wear, more durable, and has good wear stability; and the thermometer prepared by the non-functionalized eggshell membrane ESM provided by the comparative example is prone to breakage and tearing during wear due to poor tensile mechanical properties, and cannot be worn stably and persistently.
[0148] The application scenarios, flexible and twistable properties, and tensile mechanical properties of the wearable thermometers provided by the embodiments 2 and 3 are similar to those of the embodiment 1.
[0149] Figure 12 The temperature-time response curve and the temperature-time scatter plot of the wearable thermometer provided by the embodiment 1 of the present application for body temperature monitoring; wherein (a) is the temperature-time response curve of the forehead temperature of a healthy male, and in specific implementation, the wearable thermometer can be attached to the forehead of a healthy male; (b) is the temperature-time scatter plot of the palm temperature of a healthy male monitored for 12 hours, and in specific implementation, the wearable thermometer can be worn on the palm of a healthy male and real-time temperature monitoring can be performed for 12 hours.
[0150] Referring to Figure 12 (a), it can be seen that the response time of the wearable thermometer is 5s, and the forehead temperature of the healthy male is 35.3℃. Referring to Figure 12 (b), it can be seen that the palm temperature of the healthy male is about 29-30℃ from 9am to 9pm, and the palm temperature of the healthy male is the highest at 10am and 5pm.
[0151] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even if a single embodiment is described with respect to a particular feature. The feature examples provided in the present disclosure are intended to be illustrative, not limiting, unless otherwise stated. In specific implementation, one or more technical features of the dependent claims can be combined with the technical features of the independent claims, and the technical features from the corresponding independent claims can be combined by any appropriate means rather than only by the specific combinations listed in the claims, if technically feasible.
[0152] Although the present application has been disclosed with reference to the above examples, it is not intended to limit the present application. Any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes and modifications, and the scope of protection of the present application should be limited by the scope defined in the claims.
Claims
1. A method for preparing a flexible functionalized eggshell membrane, characterized in that, include: S1, Preparation of reduced graphene oxide rGO: Graphene oxide GO is dispersed in deionized water to form a graphene oxide GO dispersion, sodium borohydride is added as a reducing agent, and the dispersion is reduced at 60-70℃ for 30-60 min. The reduced graphene oxide nanopowder rGO is obtained by centrifugation. S2, Pre-treated eggshell membrane ESM: Rinse the eggshell ES clean, place it in white vinegar at room temperature and sonicate for 30-40 minutes to peel off the eggshell membrane ESM, rinse with ultrapure water to remove residual substances, then soak the eggshell membrane ESM in sodium hydroxide at room temperature and sonicate for 30-60 minutes, rinse with deionized water to obtain pre-treated eggshell membrane ESM. S3, Preparation of polydopamine PDA precursor solution: Add dopamine DA to Tris buffer and shake thoroughly for 30-50 min to obtain polydopamine PDA precursor solution; S4, Preparation of flexible functionalized eggshell membrane ESM-PDA@rGO: The pretreated eggshell membrane ESM and reduced graphene oxide rGO nanoparticles were added to the polydopamine PDA precursor solution and polymerized at a constant temperature of 35-37℃ for 24-48h to obtain flexible functionalized eggshell membrane ESM-PDA@rGO.
2. The preparation method according to claim 1, characterized in that, In step S1, the concentration of the graphene oxide (GO) dispersion is 1-2 mg / mL, and the mass ratio of sodium borohydride to graphene oxide (GO) is (10-20):(20-40).
3. The preparation method according to claim 1, characterized in that, In step S2, the concentration of sodium hydroxide is 0.5-1M.
4. The preparation method according to claim 1, characterized in that, In step S3, The ratio of Tris to water in the Tris buffer is (2420-4840) mg: (20-40) mL, and the ratio of DA to Tris buffer in the polydopamine PDA precursor solution is (40-80) mg: (20-40) mL.
5. The preparation method according to claim 1, characterized in that, In step S4, the ratio of eggshell membrane ESM, reduced graphene oxide rGO nanopowder and polydopamine PDA precursor solution is (2-5) tablets: (20-40) mg: (20-40) mL.
6. A flexible functionalized eggshell membrane ESM-PDA@rGO obtained by the preparation method according to any one of claims 1 to 5.
7. A temperature sensor, characterized in that, Including the flexible functionalized eggshell membrane ESM-PDA@rGO as described in claim 6.
8. The temperature sensor according to claim 7, characterized in that, It includes an upper encapsulation layer, a lower encapsulation layer, a temperature-sensitive layer encapsulated between the upper and lower encapsulation layers, and lead wires connected to the temperature-sensitive layer; the temperature-sensitive layer is obtained by mechanically pressing the flexible functionalized eggshell membrane ESM-PDA@rGO; the lead wires include flexible carbon fiber.
9. The temperature sensor according to claim 8, characterized in that, The temperature-sensitive layer is obtained by mechanically pressing at least one layer of the flexible functionalized eggshell membrane ESM-PDA@rGO.
10. The application of a temperature sensor as described in any one of claims 7 to 9 in a wearable thermometer.