Preparation method of pH-sensitive film, pH-sensitive film and expiration pH detection structure

Abstract

The invention discloses a pH-sensitive film preparation method, a pH-sensitive film and an expiration pH detection structure. The pH-sensitive film preparation method comprises the following steps: dissolving ZnAc2. 2H2O in deionized water, adding a NaOH solution, mixing, carrying out a hydrothermal reaction, centrifuging, washing and drying a product to prepare rod-like ZnO, and adding ultrapure water to prepare a ZnO aqueous solution; the preparation method comprises the following steps: mixing SWCNTs (single-walled carbon nanotubes) with a ZnO aqueous solution to prepare a suspension as a precursor solution; adding the precursor solution into a mold filled with PDMS (Polydimethylsiloxane), heating and curing to form a film, stripping the film, and pre-curing, sintering and drying to obtain a pH sensitive film; a large number of hydroxyl groups exist on the surface of ZnO and can be subjected to reversible reaction with gas in exhaled air, so that the surface charge density and the exhaled air pH value are changed, the carrier concentration can be changed by adsorption / desorption of ions on the surface of ZnO, so that sensitive response to the pH value is realized, and the single-walled carbon nanotubes have excellent conductivity and high specific surface area; and after compounding with ZnO, the sensitivity of the film material to pH is further improved.

Description

[0001] In the field of technology

[0002] The present invention relates to the technical field of human breath pH detection technology, and in particular to a pH sensitive film preparation method, a pH sensitive film and a breath pH detection structure. Background Art

[0003] Normal human physiological activity depends on the internal acid-base balance (blood pH maintained between 7.35 and 7.45), and exhaled breath composition is closely related to acid-base metabolism. Exhaled breath pH-related indicators may become another vital sign, following body temperature, heart rate, and blood oxygen, and are widely used in physical examinations, disease diagnosis, and rehabilitation assessments.

[0004] However, currently, the patient's ventilation function and acid-base imbalance type are assessed through analysis of exhaled breath components to guide clinical treatment. However, since the concentration of metabolic markers in exhaled breath (such as ketone bodies and volatile organic acids) is usually at the ppb (parts per billion) or even ppt (parts per trillion) level, existing sensors (such as electrochemical sensors and metal oxide sensors) are difficult to quantify accurately and are easily affected by environmental interference (such as humidity, temperature, and external gases), and have poor detection sensitivity and specificity. Summary of the Invention

[0005] The present invention provides a pH sensitive film preparation method, a pH sensitive film and a breath pH detection structure to solve the above problems.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In one aspect, the present invention provides a method for preparing a pH sensitive film, which comprises the following steps:

[0008] S1: Dissolve ZnAc2·2H2O in deionized water, stir, add NaOH solution, transfer the mixed solution to a beaker, and perform a hydrothermal reaction; after the solution is cooled to room temperature, centrifuge, wash, and dry the product to obtain rod-shaped ZnO, and add ultrapure water to prepare a ZnO aqueous solution for later use;

[0009] S2: Mixing single-walled carbon nanotubes (SWCNTs) with a ZnO aqueous solution and ultrasonically treating the mixture to form a uniform suspension, which serves as a precursor solution.

[0010] The precursor solution is added to a mold containing PDMS, heated and cured to form a thin film, the film is peeled off from the mold, and then the film is pre-cured, sintered, and dried to obtain a pH-sensitive film.

[0011] Furthermore, the concentration of the ZnO aqueous solution is 2 mg / mL;

[0012] The mass ratio of the SWCNTs to the rod-shaped ZnO is 25:1.

[0013] Furthermore, the molar ratio of ZnAc2·2H2O to NaOH is 1:8-9.

[0014] Furthermore, in S2, the specific steps of pre-curing, sintering and drying the film are as follows: the film is first pre-cured at 200°C for 10 minutes, and then sintered at 270°C for 60 minutes; after sintering, the film is placed in a vacuum drying oven at 70°C for 60 minutes.

[0015] Furthermore, in S1, the hydrothermal reaction conditions are: reaction temperature 220° C., and reaction time 15 hours.

[0016] Furthermore, in S2, the precursor solution is heated to solidify and form a thin film by placing the mold containing the precursor solution and PDMS on a constant temperature heating table and heating at 70° C. for 2 hours.

[0017] Furthermore, in S1, the washing method is: washing with ethanol and deionized water.

[0018] Furthermore, in S1, the drying method is: drying in a vacuum drying oven at 80°C.

[0019] Another aspect of the present invention provides a self-powered structure for rapid detection of pH value in human exhaled breath based on a double-helical triboelectric nanogenerator, comprising:

[0020] The outer shell is provided with openings at both ends and is composed of a polytetrafluoroethylene film, a copper electrode layer and a protective shell arranged in sequence from the inside out, and the copper electrode layer is externally connected to a wire;

[0021] A rotating member comprising a rotating shaft and two blades spirally wound around the rotating shaft, wherein the rotating shaft is rotatably mounted on the housing, the blades are fixed to the outer circumferential surface of the rotating shaft, and the blades are provided with a pH-sensitive film, wherein the pH-sensitive film is prepared by the method for preparing a pH-sensitive film;

[0022] The blades can rotate under the thrust of the fluid entering the housing through the opening, driving the pH sensitive film and the polytetrafluoroethylene film to rub against each other to generate electric current.

[0023] Furthermore, it includes two support frames arranged at both ends of the shell, the support frames are provided with bearings, and the rotating shaft is rotatably connected to the support frames through the bearings.

[0024] Furthermore, the support frame is provided with a protrusion, and the protrusion is interference-fitted with the openings at both ends of the shell.

[0025] Furthermore, the copper electrode layer includes a first interdigital electrode and a second interdigital electrode arranged to cross each other.

[0026] In another aspect, the present invention provides a pH sensitive film, which is prepared by the method for preparing a pH sensitive film.

[0027] The beneficial effects of the present invention are:

[0028] In a method for preparing a pH-sensitive film disclosed in the present invention, ZnO, as a semiconductor metal oxide, has a large number of hydroxyl groups on its surface, which can undergo reversible reactions with acidic / alkaline gases in exhaled breath, resulting in changes in surface charge density. When the exhaled pH value changes, the adsorption / desorption of ions on the ZnO surface will change its carrier concentration (such as electrons or holes), thereby affecting its conductivity, thereby achieving a sensitive response to the pH value. Single-walled carbon nanotubes (SWCNTs) have excellent conductivity and high specific surface area. After being compounded with ZnO, they can accelerate electron transmission, amplify the electrical signals caused by pH changes, and further improve the sensitivity of the film material to pH. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 Result diagram of output voltage test of pH sensitive films prepared in Example 1 of the present invention and the control group;

[0031] Figure 2 This is a schematic structural diagram of the self-powered structure for rapid detection of pH value in human exhaled breath using a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the self-powered structure for rapid detection of pH value in human exhaled breath of a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention without the protective shell;

[0033] Figure 4 This is a schematic structural diagram of the housing of the self-powered structure for rapid detection of pH value in human exhaled breath of a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0034] Figure 5 for Figure 4 A magnified schematic diagram of point A;

[0035] Figure 6This is a schematic structural diagram of the rotating shaft and supporting frame of the self-powered structure for rapid detection of pH value in human exhaled breath of a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0036] Figure 7A Schematic diagram of the structure of the blades and pH sensitive film of the self-powered human breath pH rapid detection structure of the double-helix triboelectric nanogenerator disclosed in Example 2 of the present invention Figure 1 ;

[0037] Figure 7B Schematic diagram of the structure of the blades and pH sensitive film of the self-powered human breath pH rapid detection structure of the double-helix triboelectric nanogenerator disclosed in Example 2 of the present invention Figure 2 ;

[0038] Figure 8 This is a schematic structural diagram of the copper electrode layer and wires of the self-powered structure for rapid detection of pH value in human exhaled breath of a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0039] Figure 9 This is a diagram showing the working principle of the self-powered structure for rapid detection of pH value in human exhaled breath using a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0040] Figure 10 This is a graph showing the comparison of the currents at different pH values ​​of the self-powered structure for rapid detection of pH value in human exhaled breath using a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0041] Figure 11 This is a graph showing the voltage comparison results at different pH values ​​for the self-powered structure for rapid detection of pH value in human exhaled breath using a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0042] Figure 12 This is a result diagram of the response time and recovery time of the self-powered structure for rapid detection of pH value in human exhaled breath using a double-helical triboelectric nanogenerator disclosed in Example 2 of the present invention;

[0043] Figure 13 This is a diagram showing the results of a durability test of the self-powered human breath pH rapid detection structure of the double-helix triboelectric nanogenerator disclosed in Example 2 of the present invention.

[0044] In the picture:

[0045] 1. Housing; 11. Polytetrafluoroethylene film; 12. Copper electrode layer; 121. First interdigital electrode; 1211. First interdigital portion; 1212. First connecting portion; 122. Second interdigital electrode; 1221. Second interdigital portion; 1222. Second connecting portion; 13. Protective housing;

[0046] 2. Rotating shaft;

[0047] 3. Leaves;

[0048] 4. pH sensitive film;

[0049] 5. Support frame; 51. Protrusion;

[0050] 6. Wire. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0052] Example 1:

[0053] A method for preparing a pH sensitive film comprises the following steps:

[0054] S1: First, 1 g of ZnAc2·2H2O was dissolved in 50 mL of deionized water and stirred with a magnetic stirrer for 20 minutes. Subsequently, 20 mL of a 2 M NaOH aqueous solution (the molar ratio of ZnAc2·2H2O to NaOH was 1:8.8) was added to the solution and stirred for 20 minutes. The mixed solution was then transferred to a beaker with a PTFE liner and placed in an autoclave for a hydrothermal reaction at 220°C for 15 hours. After the solution was cooled to room temperature, the product was centrifuged and washed several times with ethanol and deionized water. Finally, the product was dried in a vacuum drying oven at 80°C to obtain rod-shaped ZnO. The rod-shaped ZnO was added to ultrapure water and mixed to prepare a ZnO aqueous solution with a concentration of 2 mg / mL for later use.

[0055] S2: 5 g of single-walled carbon nanotubes (SWCNTs) were mixed with 100 mL of a 2 mg / mL ZnO aqueous solution (the mass ratio of SWCNTs to rod-shaped ZnO was 25:1) and ultrasonicated for 1 hour to prepare a homogeneous suspension as the precursor solution;

[0056] The precursor solution was added to a mold filled with uncured PDMS, and after thorough stirring, the mold was placed on a constant temperature heating table and heated at 70°C for 2 hours. After the solution solidified to form a thin film, the film was peeled off on a clean workbench and then placed in a muffle furnace. It was pre-cured at 200°C for 10 minutes and then sintered at 270°C for 60 minutes. After sintering, the film was placed in a vacuum drying oven and dried at 70°C for 60 minutes to prepare a pH-sensitive film, namely, a SWCNTs-PDMS-ZnO film.

[0057] In order to explore the optimal dosage ratio of single-walled carbon nanotubes (SWCNTs) and ZnO, the following control experiment was set up:

[0058] Control group 1:

[0059] The only difference between this control group and the above preparation steps is that in this control group, 1 g of single-walled carbon nanotubes (SWCNTs) was mixed with 100 mL of a 2 mg / mL ZnO aqueous solution (the mass ratio of SWCNTs to rod-shaped ZnO was 5:1) to prepare a precursor solution and obtain a pH-sensitive thin film material.

[0060] Control group 2:

[0061] The only difference between this control group and the above preparation steps is that in this control group, 10 g of single-walled carbon nanotubes (SWCNTs) were mixed with 100 mL of a 2 mg / mL ZnO aqueous solution (the mass ratio of SWCNTs to rod-shaped ZnO was 50:1) to prepare a precursor solution and obtain a pH-sensitive thin film material.

[0062] The output voltage test of the pH sensitive thin film materials prepared in the embodiment group (Example 1) and the control group 1 and the control group 2 was carried out respectively. The results are as follows: Figure 1 As shown, in order to facilitate the comparison between Example 3 and the control group, the output voltage test results of the SWCNTs-CTS-ZnO thin film materials prepared by Example 3, Control Group 1, and Control Group 2 are integrated into one figure. The test acquisition time of the three is equal. Figure 1It can be seen that compared with controls 1-2, the material in Example 1 exhibited the highest output performance in the experiment. This is attributed to the maximization of the synergistic effect achieved by the appropriate ratio of single-walled carbon nanotubes (SWCNTs) and ZnO. In Control 1, the amount of SWCNTs was too small, resulting in blocked electron transport and insufficient modification of the ZnO surface, which weakened the charge transfer efficiency. In Control 2, the amount of SWCNTs was too high, and the excess carbon nanotubes agglomerated, which not only destroyed the uniformity of the film but also occupied the reaction sites between ZnO and gas molecules, increased gas diffusion resistance, and caused a decrease in response sensitivity. The appropriate amount of SWCNTs in Example 1 not only ensured the continuity of the conductive path within the film, but also enhanced the adsorption activity of ZnO for pH-sensitive gases through surface modification, while avoiding structural defects caused by material accumulation, thereby achieving a significant increase in output voltage.

[0063] Example 2:

[0064] A self-powered rapid detection structure for pH value of human exhaled breath based on a double-helical triboelectric nanogenerator, comprising:

[0065] like Figure 2 and Figure 4 The housing 1 is provided with openings at both ends as shown. Figure 5 As shown, it is composed of a polytetrafluoroethylene film 11, a copper electrode layer 12 and a protective shell 13 arranged in sequence from the inside to the outside, and the copper electrode layer 12 is externally connected to the wire 6;

[0066] Rotating parts, such as Figure 2 、 Figure 6 、 Figure 7A and Figure 7B As shown, it includes a rotating shaft 2 and two blades 3 spirally wrapped around the rotating shaft 2, the rotating shaft 2 is rotatably arranged on the housing 1, and the blades 3 are fixed on the outer circumferential surface of the rotating shaft 2;

[0067] like Figure 7A and Figure 7B As shown, the blade 3 is provided with a pH sensitive film 4, which is attached to the blade 3 and located on the side of the blade 3 close to the user's mouth. The pH sensitive film 4 is prepared by the preparation method of the pH sensitive film disclosed in Example 1;

[0068] The blades 3 can rotate under the thrust of the fluid (gas exhaled by the user) entering the housing 1 through the opening, driving the pH sensitive film 4 and the polytetrafluoroethylene film 11 to rub against each other to generate current.

[0069] The gas exhaled by the user flows in the housing 1. After leaving the human mouth, the gas is cooled by the ambient temperature to form micro droplets, which adhere to the pH sensitive film 4 and the polytetrafluoroethylene film 11. The airflow generated when blowing drives the blades 3 to rotate, causing the pH sensitive film 4 to rotate rapidly. Rapid friction occurs between the pH sensitive film 4 and the polytetrafluoroethylene film 11, thereby generating an electrical signal.

[0070] The pH value of human exhaled breath will affect the pH value of micro-droplets. Micro-droplets with different pH values ​​have different effects on the electron flow capacity of the dielectric film, and the current and voltage of the generated electrical signals are also different. The external gas detection module is responsible for receiving and processing the electrical signals. The data obtained after processing is displayed through terminal devices such as mobile phones that are wirelessly connected to the gas detection module, allowing users to intuitively read the pH value.

[0071] Specifically, if Figure 3 and Figure 6 As shown, the housing 1 further includes two support frames 5 disposed at both ends thereof. The support frames 5 are provided with bearings, and the rotating shaft 2 is rotatably connected to the support frames 5 via the bearings.

[0072] Specifically, if Figure 6 As shown, the support frame 5 is provided with a protrusion 51 , and the protrusion 51 is interference-fitted with the openings at both ends of the housing 1 , making the assembly of the support frame 5 easier.

[0073] Specifically, if Figure 3 As shown, the copper electrode layer 12 includes a first interdigitated electrode 121 and a second interdigitated electrode 122 arranged to cross each other. The working principle of triboelectricity is as follows: Figure 9 As shown, the essence is to generate electrical signals through the transfer of electrons;

[0074] like Figure 8 As shown, the first interdigitated electrode 121 includes a first connecting portion 1212 and a plurality of first interdigitated portions 1211 connected to the first connecting portion 1212 . The plurality of first interdigitated portions 1211 are arranged parallel to each other and spaced apart. The first connecting portion 1212 is connected to the wire 6 .

[0075] The second interdigital electrode 122 includes a second connecting portion 1221 and a plurality of second interdigital portions 1221 connected to the second connecting portion 1222 . The plurality of second interdigital portions 1221 are arranged parallel to each other and spaced apart. The second connecting portion 1222 is connected to the wire 6 .

[0076] The first interdigital portions 1211 and the second interdigital portions 1221 are spaced apart from each other and arranged in a staggered manner.

[0077] Specifically, the blade 3 is made of PET, and the protective shell 13 is made of PLA.

[0078] To better illustrate the technical effects of this embodiment, we first compare the current and voltage of the electrical signal of the detection structure at different pH values. This further explores the pH detection capability of the self-powered rapid detection structure for human exhaled breath pH based on a double-helical triboelectric nanogenerator disclosed in this embodiment in a simulated natural human exhaled breath environment. The following experiments verify its performance under different pH environments.

[0079] The specific testing method is as follows: The test structure is placed in a sealed test chamber in a constant temperature (25°C) and humidity (80% relative humidity) environment. Saturated vapor with a specific pH value (pH = 1-13) is introduced using an atomizer to simulate human exhalation, with a fixed gas flow rate of 1.5 L / min (simulating natural exhalation flow). The current signal is recorded in real time using an electrostatic high resistance meter (sampling rate 100 Hz). Each set of pH values ​​is tested three times and the average value is obtained.

[0080] The test results are as follows Figure 10 and Figure 11 As shown, Figure 10 and Figure 11 In order to facilitate the comparison of the overall trend of the output current and voltage at different pH values, the test results at different pH values ​​are integrated into one figure. The acquisition time of each test is equal. When the pH values ​​are set to 1, 3, 5, 7, 9, and 13, the current and voltage of the measured electrical signal fluctuate over time. When the experiment was carried out in an acidic breath environment with pH = 1, the voltage was measured to be 29.1V and the current was 0.398mA. As the pH value increased, the voltage decreased but remained stable. When the pH reached 9, the voltage began to rise again and reached a peak when the pH reached 13, at which time VOC = 57.9V and ISC = 0.615mA. This shows that the output electrical signal of the pH-TENG formed by the pH sensitive film 4 and the polytetrafluoroethylene film is significantly affected by the acidity and alkalinity of the solution. This phenomenon can be attributed to the fact that the acidic or alkaline solution simulates the exhaled gas of the human body, resulting in the hydrogen ions (H + ) or hydroxyl ion (OH - ) concentration, thereby increasing the triboelectric charge density on the surface of the pH-sensitive film. This effect can be attributed to the fact that strong acid or base conditions lead to more mechanical free radicals and stronger electron transfer. Strong acid and base environments may change the electrochemical properties of the electrode surface, such as surface potential and charge density, thereby affecting the generation and transmission of electrical signals and leading to differences in current fluctuations. In contrast, in a neutral environment, these effects are relatively weakened, resulting in lower levels of both voltage and current.

[0081] To better illustrate the practical effect of the self-powered rapid detection structure of human exhaled pH value based on a double-helical triboelectric nanogenerator disclosed in this embodiment, the response time and recovery time tests are used to illustrate the effect.

[0082] The specific test method for response time is:

[0083] In a constant temperature (25°C) and constant humidity (relative humidity 80%) environment, the detection structure is placed in a closed test chamber. Use an atomization device to introduce saturated steam with a specific pH value (such as pH = 13) to simulate human exhalation, and the gas flow rate is fixed at 1.5L / min (simulating natural exhalation flow). The current signal is recorded in real time by a high-precision oscilloscope (sampling rate 1kHz). The response time is defined as the time required for the current value to rise from the initial baseline to 90% of the steady-state value. Each group of pH values ​​is tested three times and the average value is taken.

[0084] The test results are as follows Figure 12 As shown in the figure, under the environmental condition of pH 13, the measured response time is about 149 milliseconds and the recovery time is about 186 milliseconds. The response speed is fast, which is conducive to continuous monitoring of the exhaled pH value. The recovery time is short, which is conducive to continuous monitoring of the exhaled pH value.

[0085] The specific test method for durability test is:

[0086] In a constant temperature (25°C) and humidity (relative humidity 80%) environment, atomized steam with pH = 7, pH = 10, or pH = 4 was circulated through a blower at a flow rate of 1.5 L / min (exhalation for 2 seconds and inhalation for 2 seconds, one exhalation and one exhalation as one cycle) for 3600 breathing cycles. The peak voltage of each cycle was recorded in real time using an electrostatic high resistance meter (sampling rate 100 Hz).

[0087] The test results are as follows Figure 13 As shown in the figure, after about 3600 consecutive cycles of testing in a simulated exhalation environment, the output voltage remained basically stable, which shows that the structure has excellent mechanical stability and is suitable for subsequent gas-sensing performance testing.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a pH sensitive film, characterized in that: The following steps are involved: S1: Dissolve ZnAc2·2H2O in deionized water, stir, add NaOH solution, transfer the mixed solution to a beaker, and perform a hydrothermal reaction; after the solution is cooled to room temperature, centrifuge, wash, and dry the product to obtain rod-shaped ZnO, and add ultrapure water to prepare a ZnO aqueous solution for later use; S2: Mixing single-walled carbon nanotubes (SWCNTs) with a ZnO aqueous solution and ultrasonically treating the mixture to form a uniform suspension, which serves as a precursor solution. The precursor solution is added to a mold containing PDMS, heated and cured to form a thin film, the film is peeled off from the mold, and then the film is pre-cured, sintered, and dried to obtain a pH-sensitive film.

2. The method for preparing a pH sensitive film according to claim 1, wherein: The concentration of the ZnO aqueous solution is 2 mg / mL; The mass ratio of the SWCNTs to the rod-shaped ZnO is 25:

1.

3. The method for preparing a pH sensitive film according to claim 1, wherein: The molar ratio of ZnAc2·2H2O to NaOH is 1:8-9.

4. The method for preparing a pH sensitive film according to claim 1, wherein: In S2, the specific steps of pre-curing, sintering and drying the film are as follows: the film is first pre-cured at 200°C for 10 minutes, and then sintered at 270°C for 60 minutes; after sintering, the film is placed in a vacuum drying oven at 70°C for 60 minutes.

5. The method for preparing a pH sensitive film according to claim 1, wherein: In S1, the hydrothermal reaction conditions are: reaction temperature 220° C., reaction time 15 hours.

6. A pH sensitive film, characterized in that The pH sensitive film is prepared by the preparation method of the pH sensitive film according to claim 1.

7. A self-powered rapid detection structure for pH value of human exhaled breath based on a double-helical triboelectric nanogenerator, characterized in that: include: A housing (1) with openings at both ends is composed of a polytetrafluoroethylene film (11), a copper electrode layer (12) and a protective shell (13) arranged in sequence from the inside out, wherein the copper electrode layer (12) is externally connected to a wire (6); A rotating member, comprising a rotating shaft (2) and two blades (3) spirally wound around the rotating shaft (2), wherein the rotating shaft (2) is rotatably arranged on the housing (1), and the blades (3) are fixed on the outer circumferential surface of the rotating shaft (2), and a pH sensitive film (4) is provided on the blades (3), and the pH sensitive film (4) is prepared by the preparation method of the pH sensitive film according to claim 1; The blades (3) can rotate under the thrust of the fluid entering the housing (1) through the opening, driving the pH sensitive film (4) and the polytetrafluoroethylene film (11) to rub against each other and generate electric current.

8. The self-powered rapid detection structure for pH value of human exhaled breath based on a double-helical triboelectric nanogenerator according to claim 7, characterized in that: It also includes two support frames (5) arranged at both ends of the housing (1), the support frames (5) are provided with bearings, and the rotating shaft (2) is rotatably connected to the support frames (5) via the bearings.

9. The self-powered rapid detection structure for pH value of human exhaled breath based on a double-helical triboelectric nanogenerator according to claim 7, characterized in that: The support frame (5) is provided with a raised portion (51), and the raised portion (51) is interference-fitted with the openings at both ends of the housing (1).

10. The self-powered rapid detection structure for pH value of human exhaled breath based on a double-helical triboelectric nanogenerator according to claim 7, characterized in that: The copper electrode layer (12) comprises a first interdigitated electrode (121) and a second interdigitated electrode (122) arranged to intersect with each other.

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