A light-trapping and sensitized optical fiber pH temperature sensor and its preparation method

Abstract

The present invention provides a light-trapping and enhanced-sensitivity optical fiber pH temperature sensor and a preparation method thereof, relating to the field of soil detection technology. The sensor comprises a pH optical fiber sensor, wherein the optical fiber sensing layer comprises: a pH-sensitive layer, a silver mirror, a fiber core, and an optical fiber cladding. The pH-sensitive layer has a plurality of non-directionally distributed light-reflecting structures within it, and the light-reflecting structures are achieved by adding two-dimensional materials and / or three-dimensional materials during the preparation stage of the optical fiber sensing layer. The sensor solves the technical problems existing in the prior art, such as the inability to balance the sensor's response time and recovery time, low sensitivity in low-moisture soil environments, and lack of effective temperature response correction. Based on the principle of evanescent wave absorption, a coating with a light-trapping effect is constructed at the interface of the optical fiber sensor, while enhancing the coating's rapid hydrogen ion transmission characteristics. The sensor is coupled to an optical fiber temperature sensor to calibrate the pH measurement value, thereby achieving in-situ, precise measurement of the pH and temperature of a heterogeneous soil system.

Description

Technical Field

[0001] The present invention relates to the technical field of soil detection, and in particular to a light-trapping and sensitized optical fiber pH temperature sensor and a preparation method thereof. Background Art

[0002] The diversity of soil phases results in a complex, heterogeneous state, which makes in-situ soil pH measurement challenging. Soil pH measurement is primarily based on the concentration of hydrogen ions in the soil. Therefore, rapid in-situ soil pH measurement requires enhanced hydrogen ion transmission within the sensor to enable rapid measurement of soil pH.

[0003] Current pH sensors primarily focus on electrode material modification and electrode structure design, but they lack specific improvements for pH measurement in soil environments. Fiber-optic sensors can detect targets by utilizing changes in the optical signal caused by the substance being measured. Nanostructured thin film coatings applied to optical fibers can modulate the propagation mode of the pipeline. Therefore, the environmental response characteristics of the thin film coating can be exploited to achieve fiber-optic sensing, while maintaining the sensitivity, interference resistance, and stability of electrodes.

[0004] Due to the limitations of existing technologies, it is impossible to take into account both the response time and recovery time of the sensor. At the same time, the sensitivity is low in low soil moisture environments, and there is a lack of effective temperature response correction. Summary of the Invention

[0005] The present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof, which are used to solve the technical problems in the prior art that the response time and recovery time of the sensor cannot be taken into account at the same time, the sensitivity is low in a low-moisture soil environment, and there is a lack of effective temperature response correction. The present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof. By constructing a coating with a light-trapping effect on the interface of the optical fiber sensor, and at the same time enhancing the coating's rapid transmission characteristics for hydrogen ions, the optical fiber temperature sensor is coupled to calibrate the pH measurement value, thereby realizing in-situ precise measurement of the pH temperature of the soil heterogeneous system.

[0006] In order to solve the above problems, the present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof, including: a pH optical fiber sensor, the coating thickness of the optical fiber sensing layer is in a preset range, and has multiple non-directionally distributed light reflection structures.

[0007] Preferably, the optical fiber sensing layer includes: a pH sensitive layer, wherein the pH sensitive layer has the plurality of non-directionally distributed light reflecting structures.

[0008] Preferably, the pH optical fiber sensor further comprises: a silver mirror; a fiber core, a first end of the fiber core being connected to the silver mirror; and an optical fiber cladding, the optical fiber cladding wrapping the second end of the fiber core.

[0009] Preferably, the pH optical fiber sensor further comprises: the light reflection structure is realized by adding two-dimensional material and / or three-dimensional material during the preparation stage of the optical fiber sensing layer.

[0010] Preferably, the light-trapped and sensitized optical fiber pH temperature sensor further includes: a light source transmitter, a wavelength division multiplexing module, a sensing module, a spectrum analyzer and an optical fiber; wherein the light source transmitter, the wavelength division multiplexing module, the sensing module and the spectrum analyzer are connected in sequence through the optical fiber, and the sensing module includes the pH optical fiber sensor.

[0011] Preferably, the sensing module comprises: a protective housing; a temperature optical fiber sensor, wherein the temperature optical fiber sensor is communicatively connected to the pH optical fiber sensor; wherein the pH optical fiber sensor and the temperature optical fiber sensor are deployed in the protective housing.

[0012] Preferably, the method for preparing the light-trapping and sensitized optical fiber pH temperature sensor is used to prepare the pH optical fiber sensor, comprising:

[0013] S1: Oxidation treatment of the optical fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide;

[0014] S2: When the optical fiber is oxidized to a preset state or a first preset time, immersing the treated optical fiber in a cationic polymer solution containing a positive charge, and taking it out after standing for a second preset time, wherein the cationic polymer solution contains pH-responsive dye molecules;

[0015] S3: placing the optical fiber from step S2 again in a negatively charged anionic polymer solution, leaving it to stand for a third preset time, and then taking it out, wherein the anionic polymer solution contains a two-dimensional material and / or a three-dimensional material;

[0016] S4: Repeat steps S2 and S3 to prepare a pH optical fiber sensor with a preset thickness.

[0017] Preferably, the two-dimensional material and / or the three-dimensional material are prepared by a mechanical exfoliation method or a chemical exfoliation method.

[0018] Preferably, the distribution of the two-dimensional material and / or the three-dimensional material and the pH-responsive dye molecules in the anionic and cationic polymer solution can be interchanged.

[0019] In view of the above problems, the present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof.

[0020] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0021] The embodiment of the present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof, comprising: S1: oxidizing the optical fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide; S2: when the optical fiber is oxidized to a preset state or a first preset time, immersing the treated optical fiber in a cationic polymer solution containing a positive charge, and taking it out after standing for a second preset time, wherein the cationic polymer solution contains pH-responsive dye molecules; S3: placing the optical fiber of step S2 again in a negatively charged anionic polymer solution, and taking it out after standing for a third preset time, wherein the anionic polymer solution contains Two-dimensional materials and / or three-dimensional materials; S4: repeat steps S2 and S3 to prepare a pH fiber optic sensor with a preset thickness, which solves the technical problems in the prior art that the response time and recovery time of the sensor cannot be taken into account at the same time, the sensitivity is low in a low-moisture environment in the soil, and there is a lack of effective temperature response correction. Based on the principle of evanescent wave absorption, a coating with a light trapping effect is constructed on the interface of the fiber optic sensor, and the coating's rapid transmission characteristics for hydrogen ions are enhanced. The pH measurement value is calibrated by coupling the fiber optic temperature sensor, thereby realizing in-situ precise measurement of the pH temperature of the soil heterogeneous system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below 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 application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 A schematic diagram of the structure of a fiber optic pH sensor probe is provided for this application;

[0024] Figure 2 The present application provides a structural schematic diagram of an embodiment of a light-trapped optical fiber pH temperature sensor device;

[0025] Figure 3 A schematic diagram of the principle of optical fiber pH sensor probe sensitivity enhancement is provided for this application;

[0026] Figure 4 Provided for this application are the sensitivity test results of the optical fiber pH sensor probe in the embodiments;

[0027] Figure 5 This application provides a flow chart of a method for preparing a light-trapping-sensitized optical fiber pH temperature sensor.

[0028] Explanation of the reference numerals: silver mirror 01, including fiber core 02, pH sensitive layer 03, fiber cladding 04, light source transmitter 10, optical fiber 11, wavelength division multiplexing module 30, protective shell 31, pH fiber optic sensor 32, temperature fiber optic sensor 33, sensing module 34, spectrum analyzer 20. DETAILED DESCRIPTION

[0029] To make the above-mentioned purposes, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the description of the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The term "and / or" as used herein includes any and all combinations of one or more of the relevant listed items.

[0031] Technical Concept

[0032] This application solves the technical problems in the prior art of being unable to balance the response time and recovery time of the sensor, having low sensitivity in low soil moisture environment, and lacking effective temperature response correction by providing a light-trapping and sensitized optical fiber pH temperature sensor and a preparation method thereof.

[0033] The technical solution in the present application has the following main technical structure: a pH optical fiber sensor, wherein the coating thickness of the optical fiber sensing layer is within a preset range and has a plurality of non-directionally distributed light reflecting structures. The optical fiber sensing layer includes: a pH sensitive layer, wherein the pH sensitive layer has the plurality of non-directionally distributed light reflecting structures. The pH optical fiber sensor also includes: a silver mirror; a fiber core, wherein the first end of the fiber core is connected to the silver mirror; and an optical fiber cladding, wherein the optical fiber cladding wraps the second end of the fiber core. The pH optical fiber sensor also includes: the light reflecting structure is realized by adding two-dimensional materials and / or three-dimensional materials during the preparation stage of the optical fiber sensing layer. By introducing two-dimensional materials into the optical fiber sensing layer, the two-dimensional materials can increase the transmission path of light in the sensing layer. Under the premise of a low-thickness sensing layer, the light trapping characteristics can be used to improve the detection sensitivity of the sensing layer to pH, and provide a fast channel for the transmission of hydrogen ions in the sensing layer, thereby improving the response rate of pH detection.

[0034] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] Example 1

[0036] like Figure 1 As shown, the present application provides a light-trapping-sensitized optical fiber 11 pH temperature sensor and its preparation method, including: a pH optical fiber sensor 32, the coating thickness of the optical fiber sensing layer is in a preset range, and has multiple non-directionally distributed light reflection structures.

[0037] Furthermore, the optical fiber sensing layer includes: a pH sensitive layer 03 , wherein the pH sensitive layer 03 has the plurality of non-directionally distributed light reflection structures.

[0038] Furthermore, the pH optical fiber sensor 32 further includes: a silver mirror 01; a fiber core 02, wherein a first end of the fiber core 02 is connected to the silver mirror 01; and an optical fiber cladding 04, wherein the optical fiber cladding 04 wraps the second end of the fiber core 02.

[0039] Furthermore, the pH optical fiber sensor 32 further includes: the light reflection structure is realized by adding two-dimensional material and / or three-dimensional material during the preparation stage of the optical fiber sensing layer.

[0040] Specifically, if Figure 1 As shown, the pH optical fiber sensor 32 includes the silver mirror 01, the fiber core 02, the pH sensitive layer 03 and the optical fiber cladding 04. The silver mirror 01 is made of silver paste. The fiber core 02 serves as a transmission conductor, with a first end connected to the silver mirror 01 and the other end wrapped with the optical fiber cladding 04. The pH sensitive layer 03 is a coating on the outer periphery of the fiber core 02 and has a light trapping effect. The pH sensitive layer 03 has the multiple non-directionally distributed light reflection structures.

[0041] The light reflection structure is achieved by adding two-dimensional materials and / or three-dimensional materials during the preparation stage of the optical fiber sensing layer. By adding and introducing two-dimensional materials and / or three-dimensional materials during the preparation stage of the optical fiber sensing layer, the hydrogen ion conductivity performance of the pH sensitive layer 03 is greatly improved, and rapid transmission of hydrogen ions can be achieved in a soil environment with a low water content, thereby effectively reducing the response time of the sensor.

[0042] By adding two-dimensional materials and / or three-dimensional materials to the response coating, the light trapping effect characteristics are exhibited, and the sensitivity of the coating can be greatly improved under low film thickness conditions. The coating thickness of the optical fiber sensing layer is within a preset range and has multiple non-directionally distributed light reflection structures.

[0043] Example 2

[0044] The present application provides a light-trapping-sensitized optical fiber pH temperature sensor, including the pH optical fiber sensor 32 described in any one of the first embodiments.

[0045] Furthermore, the light-trapped and sensitive optical fiber pH temperature sensor also includes: a light source transmitter 10, a wavelength division multiplexing module 30, a sensing module 34, a spectrum analyzer 20 and an optical fiber 11; wherein the light source transmitter 10, the wavelength division multiplexing module 30, the sensing module 34 and the spectrum analyzer 20 are connected in sequence through the optical fiber 11, and the sensing module 34 includes the pH optical fiber sensor 32.

[0046] Furthermore, the sensing module 34 includes: a protective shell 31 ; a temperature fiber optic sensor 33 , wherein the temperature fiber optic sensor 33 is communicatively connected to the pH fiber optic sensor 32 ; wherein the pH fiber optic sensor 32 and the temperature fiber optic sensor 33 are deployed in the protective shell 31 .

[0047] Specifically, if Figure 2 As shown, the light source transmitter 10 , the wavelength division multiplexing module 30 and the spectrum analyzer 20 are connected in sequence through the optical fiber 11 .

[0048] Among them, the sensing module 34 includes the protective shell 31, the pH optical fiber sensor 32 and the temperature optical fiber sensor 33. The pH optical fiber sensor 32 and the temperature optical fiber sensor 33 are deployed in the protective shell 31. By communicatively connecting the temperature optical fiber sensor 33 with the pH optical fiber sensor 32 and integrating the two, the pH can be calibrated through the optical fiber temperature sensor, thereby improving the accuracy of the pH test.

[0049] Example 3

[0050] In addition to the above method for preparing a light-trapping-sensitized optical fiber pH temperature sensor, there are also steps for preparing the device, including:

[0051] S1: oxidizing the optical fiber 11 in a mixed solution of concentrated sulfuric acid and hydrogen peroxide;

[0052] S2: When the optical fiber 11 is oxidized to a preset state or a first preset time, the treated optical fiber 11 is immersed in a cationic polymer solution containing a positive charge, and is taken out after standing for a second preset time, wherein the cationic polymer solution contains pH-responsive dye molecules;

[0053] S3: placing the optical fiber 11 from step S2 again in the negatively charged anionic polymer solution, leaving it to stand for a third preset time, and then taking it out, wherein the anionic polymer solution contains a two-dimensional material and / or a three-dimensional material;

[0054] S4: Repeat steps S2 and S3 to prepare a pH optical fiber sensor 32 with a preset thickness.

[0055] Furthermore, the two-dimensional material and / or the three-dimensional material are prepared by a mechanical exfoliation method or a chemical exfoliation method.

[0056] Furthermore, the distribution of the two-dimensional material and / or the three-dimensional material and the pH-responsive dye molecules in the anionic and cationic polymer solution can be interchanged.

[0057] Specifically, Example 3 of the present application provides a preparation step of a pH optical fiber sensor 32, wherein the cationic polymer is one or a combination of polydiallyldimethylammonium chloride and polyacrylammonium hydrochloride; the anionic polymer is one or a combination of sodium carboxymethyl cellulose and polyacrylic acid; the pH-responsive dye molecule is one or a combination of thymol blue, methyl yellow, methyl orange, bromophenol blue, bromocresol green, bromocresol purple, methyl red, bromothymol blue, neutral red, phenol red, phenolphthalein, and thymolphthalein; the two-dimensional material and / or three-dimensional material is one or a combination of graphene, graphene oxide, transition metal sulfide, black phosphorus, hexagonal boron nitride, MXene, single-layer electrolyte titanate (IV) nanosheets, transition metal phosphosulfide, graphitic carbon nitride and modified materials.

[0058] By introducing two-dimensional materials and / or three-dimensional materials into the optical fiber sensing layer, the two-dimensional materials and / or three-dimensional materials can increase the transmission path of light in the sensing layer. Under the premise of a low-thickness sensing layer, the detection sensitivity of the sensing layer to pH is improved through the light trapping characteristics. At the same time, the two-dimensional materials and / or three-dimensional materials can also provide a fast channel for the transmission of hydrogen ions in the sensing layer, reducing the pH detection response time for heterogeneous media such as soil.

[0059] The preparation method of the pH optical fiber sensor 32 and its sensitivity characteristics are described below:

[0060] After stripping the cladding of the first 1 cm of an optical fiber 11 with a core diameter of 200 μm and a cladding thickness of 12 μm, the fiber was placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 7:3 and heated to 100°C for 10 minutes to give it a negative charge on the surface;

[0061] The pH sensitive layer 03 is prepared by a layer-by-layer self-assembly method, and then immersed in a mixed solution of polydiallyldimethylammonium chloride and neutral red for 2 minutes, wherein the concentration of polydiallyldimethylammonium chloride is 0.02M and the concentration of neutral red is 0.001M, wherein the first preset time length is 2 minutes;

[0062] After standing for 1 minute, the optical fiber head is immersed in a mixed solution of graphene oxide and polyacrylic acid again for 2 minutes, wherein the concentration of polyacrylic acid is 0.20M, the concentration of graphene oxide is 0.1wt%, the diameter of graphene oxide is 10-100nm, the average diameter is 50nm, and the thickness is 1-3nm, wherein the second preset time length is 1 minute, and the third preset time length is 2 minutes;

[0063] The ionic polymer solution and the anionic polymer solution were allowed to stand for 10 times to complete the preparation of the pH sensitive layer 03. At the same time, an optical fiber sensor probe without graphene oxide components was prepared as a blank control in the same manner.

[0064] The light propagation law of the pH sensitive layer 03 is described as follows:

[0065] like Figure 3 As shown, 1-1 is the pH sensitive layer 03, in which two-dimensional materials and / or three-dimensional materials are dispersed, 1-2 is the core 02, the light source is transmitted in the core 02, and the evanescent wave propagates to the pH sensitive layer 03. The propagation path of the evanescent wave in the space without the addition of two-dimensional materials and / or three-dimensional materials is shown in 1-3, and the propagation law of the evanescent wave in the coating with the addition of two-dimensional materials is shown in Figure 1-4 The high refractive index and reflective effect of graphene change the microscopic propagation path of the evanescent wave, thereby improving the coating's absorption of the evanescent wave and increasing the sensitivity of the sensor.

[0066] The performance of the pH optical fiber sensor 32 was tested:

[0067] The pH optical fiber sensor 32 was compared with a blank control and analyzed. Figure 4The figure shows the linear response curve of the sensor at a wavelength of 525 nm. It can be seen that the pH fiber optic sensor 32 electrode prepared by the present invention has a significant improvement over the blank control. The pH range of the pH fiber optic sensor 32 relative to the blank sensor is increased from 4-7 to 3-8. At the same time, its response time is reduced from 120 seconds to 20 seconds, and its recovery time is reduced from 300 seconds to 80 seconds.

[0068] Example 4

[0069] Example 4 of the present application provides a preferred embodiment of temperature-corrected pH:

[0070] 1. The test shows the pH detection effect of pH fiber optic sensor 32 in soil environment

[0071] S10: Prepare a pH fiber optic sensor 32 with reference to Example 1, and replace the pH response dye molecules with a combination of bromophenol blue and bromocresol blue in a ratio of 1:1 and a total concentration of 0.001M. Since the color change ranges of bromophenol blue and bromocresol purple are 4.0-7.5 and 7.5-10.5, respectively, the applicable range of the sensor can be further improved. The wavelength of the test light source is 650nm.

[0072] S20: simulated soils with moisture contents of 5%, 10%, 15%, 20%, and 25% were prepared, and experiments were conducted using modified sensors and blank sensors, respectively. The experimental data are as follows:

[0073] Table 1. Response time and recovery time of the sensor in soils with different moisture contents

[0074]

[0075] From the above data, it can be seen that the solution adopted in this patent has significant advantages.

[0076] 2. Temperature Correction pH Test Instructions

[0077] S100: The pH optical fiber sensor 32 prepared in Example 3 is combined with the temperature optical fiber sensor 33 to illustrate the effect of temperature correction on the test results.

[0078] S200: Calibrate the temperature optical fiber sensor 33 module. Figure 2 is the relationship between the calibrated ambient temperature and the Bragg wavelength value.

[0079] Table 2. Relationship between ambient temperature and Bragg wavelength

[0080]

[0081] S300: Calibrate the ambient temperature of the pH fiber optic sensor 32 based on the relationship between the temperature and Bragg wavelength obtained by the temperature fiber optic sensor 33. Calibrate the pH sensor 32 using a pH of 5.0 as an example. The calibration electrode is a pH electrode with temperature compensation. The calibration results are shown in Table 3.

[0082] Table 3. Temperature calibration of pH sensors

[0083]

[0084] It can be seen that the pH fiber optic sensor 32 has a temperature drift characteristic, which seriously affects the reliability of the test results. The present invention uses the Horner algorithm to calibrate the pH value of the sensor. The input value x of the sensor can be related to the output value through a polynomial function. where a i It is a function of temperature t, and is further solved by polynomial function approximation The optimal solution b can be obtained through the homogeneous linear equations ji , x i Represents the i-th sensor input value, t j Characterize the jth temperature acquisition result, b ji Representation and the i-th x i The input value corresponds to the jth t j The emission wavelength corresponding to the temperature value can be understood as follows: at any temperature, multiple wavelengths are emitted and multiple sensor input values, i.e., pH values, are collected. Any of the multiple temperature values ​​is denoted as j, and any of the multiple wavelengths and multiple sensor input values ​​at any temperature is denoted as i. M is the maximum value of j, and N is the maximum value of i.

[0085] Convert the above formula into matrix form: T=(t 1 ···t M ), y=T·B·X, T represents the acquisition result at temperature t, t 1 ···t M represents the temperature acquisition results from the first to the Mth time, B represents the emission wavelength, each horizontal row of the determinant represents N different emission wavelengths at the same temperature, the vertical column represents M groups of wavelengths corresponding to each temperature, A represents the product of T and B, and X represents the input value of the sensor, that is, the pH monitoring result that needs to be corrected. After calibrating the sensor, accurate measurement of pH values ​​at different temperatures can be achieved.

[0086] The technical methods provided in the embodiments of the present application have at least the following technical effects or advantages:

[0087] 1. The present application provides a light-trapping-sensitized optical fiber pH temperature sensor and a preparation method thereof, which are used for in-situ measurement of pH in a soil environment with a certain water content. By adding a two-dimensional material to the pH-responsive coating, the light-trapping effect characteristics are exhibited, and the sensitivity of the coating can be greatly improved under low film thickness conditions.

[0088] 2. By introducing two-dimensional materials, the hydrogen ion conductivity of the pH-responsive coating is greatly improved, and rapid hydrogen ion transmission can be achieved in a soil environment with a low water content, thereby effectively reducing the response time of the sensor.

[0089] 3. By coupling the fiber optic temperature sensor with the pH fiber optic sensor, the pH measurement value can be corrected by the fiber optic temperature sensor, thereby improving the accuracy of in-situ measurement of pH temperature in soil heterogeneous systems.

[0090] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0091] Obviously, those skilled in the art may make various changes and modifications to the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations.

[0092] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a light-trapping and sensitized optical fiber pH temperature sensor, characterized in that: The method includes: S1: Oxidation treatment of the optical fiber in a mixed solution of concentrated sulfuric acid and hydrogen peroxide; S2: When the optical fiber is oxidized to a preset state or a first preset time, immersing the treated optical fiber in a cationic polymer solution containing a positive charge, and taking it out after standing for a second preset time, wherein the cationic polymer solution contains pH-responsive dye molecules; S3: placing the optical fiber from step S2 again in a negatively charged anionic polymer solution, leaving it to stand for a third preset time, and then taking it out, wherein the anionic polymer solution contains a two-dimensional material and / or a three-dimensional material; S4: Repeat steps S2 and S3 to prepare a pH optical fiber sensor with a preset thickness; The cationic polymer is one or a combination of polydiallyldimethylammonium chloride and polyacrylammonium hydrochloride; The anionic polymer is one or a combination of sodium carboxymethyl cellulose and polyacrylic acid; The two-dimensional material and / or three-dimensional material is one or a combination of graphene, graphene oxide, transition metal sulfide, black phosphorus, hexagonal boron nitride, MXene, and graphite-phase carbon nitride; The coating thickness of the optical fiber sensing layer of the optical fiber pH temperature sensor prepared based on this method is within a preset range, and has multiple non-directionally distributed light reflection structures. The light reflection structures are achieved by adding two-dimensional materials and / or three-dimensional materials during the preparation stage of the optical fiber sensing layer.

2. The method according to claim 1, wherein The two-dimensional material and / or the three-dimensional material are prepared by a mechanical exfoliation method or a chemical exfoliation method.

3. The method according to claim 1, wherein The distribution of the two-dimensional material and / or the three-dimensional material and the pH-responsive dye molecules in the anionic and cationic polymer solution can be interchanged.

4. The method according to claim 1, wherein The optical fiber sensing layer includes a pH sensitive layer, wherein the pH sensitive layer has the plurality of non-directionally distributed light reflecting structures.

5. The method according to claim 1, wherein The optical fiber pH temperature sensor also includes: Silver mirror; a fiber core, wherein a first end of the fiber core is connected to the silver mirror; An optical fiber cladding wraps the second end of the optical fiber core.

6. The method according to claim 1, wherein The optical fiber pH temperature sensor further comprises: a light source transmitter, a wavelength division multiplexing module, a sensing module, a spectrum analyzer and an optical fiber; The light source transmitter, the wavelength division multiplexing module, the sensing module and the spectrum analyzer are connected in sequence through the optical fiber, and the sensing module includes the pH optical fiber sensor.

7. The method according to claim 6, wherein The sensing module includes: Protective shell; a temperature optical fiber sensor, the temperature optical fiber sensor being communicatively connected to the pH optical fiber sensor; Wherein, the pH optical fiber sensor and the temperature optical fiber sensor are deployed in the protective shell.

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