Bimodal multi-zone corrosion type optical fiber concentration sensor based on microfluidics

Abstract

The invention relates to the technical field of photoelectricity, in particular to a bimodal multi-zone corrosion type optical fiber concentration sensor based on microfluidics, and the bimodal multi-zone corrosion type optical fiber concentration sensor comprises a corrosion table module which is used for fixing an optical fiber and providing a corrosion and measurement space and is internally provided with a sectional type multi-zone corrosion space and a microfluidics fluid channel; the optical fiber sensing module adopts a single-mode optical fiber to penetrate through the corrosion table module, the surface of the optical fiber sensing module is corroded by hydrofluoric acid to form a multi-segment sensing area, and the optical fiber sensing module is used for simultaneously detecting light intensity attenuation and wavelength shift bimodal optical signals; and the micro-pipeline waste liquid discharge module is communicated with each corrosion space of the corrosion table module. According to the optical fiber concentration sensor designed by the invention, accurate measurement of the magnesium chloride solution is realized, the cost is low, the advantages of high sensitivity, good repeatability, wide application range and the like are realized, and compared with other optical fiber sensors of the same type in the aspect of sensitivity detection, the optical fiber concentration sensor has more prominent sensitivity performance during low-concentration detection and has remarkable advantages; good application values are realized.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and particularly to a dual-mode multi-region corrosion-type optical fiber concentration sensor based on microfluidics. Background Art

[0002] As a key parameter characterizing the composition and state of substances, concentration has important research significance and application value in the fields of biomedicine, environmental monitoring, food safety, industrial process control, etc. However, traditional concentration detection methods, such as chemical analysis methods, electrochemical sensors, etc., often have limitations such as cumbersome operations, slow response speeds, and difficulty in realizing on-line monitoring, and require a large amount of chemical reagents and electrical energy, resulting in energy waste and environmental pollution. With the rapid development of optical fiber communication technology, people have begun to explore the possibility of using optical fibers as sensors to detect various physical quantities, such as blood glucose concentration, temperature, refractive index, pressure, displacement, magnetic field, acceleration, etc. Among them, in terms of concentration measurement, optical fiber sensing technology has attracted the attention of some scientific research scholars due to its advantages of high sensitivity, fast response speed, remote measurability, corrosion resistance, small size, etc. Especially in some harsh environments, such as high temperature, high pressure, strong electromagnetic interference and other environments, optical fiber sensors have incomparable advantages. Therefore, the research on optical fiber concentration sensors has important value for both scientific research and practical applications.

[0003] The sensitivity enhancement of optical fiber concentration sensors is mainly achieved through two strategies: material sensitization and structural sensitization. Among them, material sensitization mainly aims to improve the sensitivity of the sensor by coating other materials such as two-dimensional materials (graphene, tungsten disulfide (WS2), tungsten diselenide (WSe2), molybdenum disulfide (MoS2)) or materials with high dielectric constants such as titanium dioxide (TiO2) and zinc oxide (ZnO) between the metal and the medium to be measured. And structural sensitization mainly improves the energy attenuation of the evanescent wave through different optical fiber structures. Currently, existing structures include side-polished optical fibers, U-shaped optical fibers, tapered optical fibers, and photonic crystal optical fibers, etc. Although the preparation technology of optical fiber sensing technology is relatively mature, there are still some limitations that need to be solved urgently in its practical application. First of all, the cost is relatively high, the equipment price is expensive, and the installation and maintenance processes are complex, increasing the overall application cost; secondly, the environmental adaptability is poor, and it is easily affected by temperature fluctuations and mechanical stresses, resulting in a decrease in measurement accuracy; finally, there are also certain deficiencies in its response speed, real-time performance, and long-term stability, making it difficult to meet some high-demand application scenarios.

[0004] Based on this, we propose an optical fiber concentration sensor with low cost, high sensitivity, and capable of realizing real-time monitoring of the concentration change of the liquid to be measured. Summary of the Invention

[0005] The object of the present invention is to overcome the above problems or at least partially solve the above problems, and a dual-mode multi-zone corrosion type optical fiber concentration sensor based on microfluidics is proposed.

[0006] To achieve the above object, the present invention provides the following technical solutions: A dual-mode multi-zone corrosion type optical fiber concentration sensor system based on microfluidics, comprising:

[0007] A corrosion stage module for fixing the optical fiber and providing a space for corrosion and measurement, which is internally provided with a segmented multi-zone corrosion space and a microfluidic fluid channel;

[0008] An optical fiber sensing module, using a single-mode optical fiber to penetrate the corrosion stage module, and its surface is corroded by hydrofluoric acid to form a multi-segment sensing area for simultaneously detecting dual-mode optical signals of light intensity attenuation and wavelength shift;

[0009] A micro-pipeline waste liquid discharge module, connected to each corrosion space of the corrosion stage module, for discharging the corrosive agent and the waste liquid to be measured;

[0010] A light source, optically connected to one end of the optical fiber sensing module, for emitting excitation light;

[0011] A spectral analysis module, optically connected to the other end of the optical fiber sensing module, for synchronously collecting dual-mode optical signals of light intensity attenuation and wavelength shift;

[0012] A data processing module, signal-connected to the spectral analysis module, for analyzing the light intensity and wavelength signals, establishing a dual-mode concentration calibration model and outputting the concentration of the analyte.

[0013] In a preferred embodiment, the corrosion stage module is made of polytetrafluoroethylene material. The corrosion stage module includes a corrosion stage main body, which is internally segmented and provided with a plurality of corrosion zones. At the position corresponding to the corrosion zone on the top of the corrosion stage main body, a lower hole is opened. The corrosion stage main body is horizontally penetrated with an optical fiber channel, and the optical fiber channel passes through the lower hole and the corrosion zone. The top of the corrosion stage main body is provided with a detachable upper cover, and the upper cover includes a cover body and an upper hole. The upper hole is opened on the upper surface of the cover body and is coaxially arranged with the lower hole to form a vertical fluid path.

[0014] In a preferred embodiment, a slot is further opened at the position corresponding to the lower hole on the top of the corrosion stage main body. A plug is provided at the bottom of the cover body, and the upper hole extends from the top of the cover body to the plug and communicates with the lower hole. The plug is adaptively inserted into the slot. Four corners of the cover body are provided with pins, and the pins are tightly inserted on the outer wall of the corrosion stage main body. The diameter of the upper hole is smaller than the diameter of the small hole.

[0015] In a preferred embodiment, the bottom of the corrosion platform body and the position corresponding to the corrosion area are also provided with interconnected waste liquid discharge ports, and the micro-channel waste liquid discharge module is connected to the corrosion area through the waste liquid discharge port.

[0016] In a preferred embodiment, the micro-channel waste liquid discharge module includes a connecting pipe, a valve and a collecting bottle which are connected in sequence, and one end of the connecting pipe away from the valve is connected to the waste liquid discharge port.

[0017] In a preferred embodiment, the upper hole and the lower hole form an input channel of the microfluidic fluid channel, and the waste liquid discharge port and the connecting pipe form an output channel of the microfluidic fluid channel.

[0018] In a preferred embodiment, the etching station module also includes a wire rack A and a wire rack B arranged in an "I" shape on both sides of the etching station body, and wire holes are provided at both ends of the side walls of the wire rack A and the wire rack B, and one of the wire holes on the wire rack A and the wire rack B is connected to the optical fiber channel, and circular holes connected to the wire holes are provided on the top of the wire rack A and the side walls of the wire rack B.

[0019] In a preferred embodiment, the etching station module also includes multiple groups of sealants that can be inserted into the etching area and encapsulated by hot melt adhesive. A through hole is opened in the middle of the sealant, and the through hole gradually decreases from top to bottom. The upper surface of the sealant contacts the optical fiber to form a planar support.

[0020] In a preferred embodiment, the sealing member includes a sealing plug plate A and a sealing plug plate B which can be plugged into each other, and the sealing plug plate A and the sealing plug plate B are respectively inserted into the adapted corrosion zone from both sides of the corrosion platform body.

[0021] The present invention also provides a concentration detection method of a dual-mode multi-zone corrosion-type optical fiber concentration sensor system based on microfluidics, comprising the following steps:

[0022] S1. Remove the coating layer on the surface of the single-mode optical fiber, clean it with alcohol and deionized water ultrasonically, and cut it into a preset length. Insert the optical fiber through the optical fiber channel of the corrosion station module and the wire frame A and the wire frame B. Connect the two ends of the optical fiber to the light source and the spectrum analysis module respectively through a fusion splicer to form a closed optical path. Insert the sealing plug-in plate A and the sealing plug-in plate B into the corrosion area and seal them with hot melt adhesive.

[0023] S2. Drip 40% hydrofluoric acid solution into the upper hole of each corrosion zone, use surface tension to form droplets to cover the optical fiber surface, and perform corrosion in two stages, the first stage corrosion for 35 minutes, and the second stage corrosion for 20 minutes. After each corrosion, drain the waste liquid through the micro-pipe waste liquid discharge module, and rinse the corrosion zone with deionized water and anhydrous alcohol in turn;

[0024] S3. Inject the test solutions with different concentrations into the upper holes of the corrosion area in sequence, so that the solutions completely infiltrate the segmented sensing area, and synchronously excite and collect the light intensity attenuation signals and wavelength shift signals of each corrosion area through the light source and the spectral analysis module;

[0025] S4. Repeat the measurement for each concentration solution at least 3 times, take the average values of the light intensity and wavelength signals, establish the dual-mode calibration curves of light intensity attenuation-concentration and wavelength shift-concentration, and obtain the concentration calculation model through fitting by the data processing module;

[0026] S5. Input the light intensity and wavelength signals of the test solution into the calibration model, output the real-time concentration value, and display it through the display screen or the terminal.

[0027] Compared with the prior art, a dual-mode multi-region corrosion type optical fiber concentration sensor based on microfluidics designed by the present invention realizes the precise measurement of magnesium chloride solution. In the 0% - 40% magnesium chloride solution, the resolution of this sensor reaches 0.0347%. Under intensity detection, the sensitivity is 2.0974 / % at low concentration and 4.1×10-3 / % at high concentration; the linearity is 96.74% at low concentration and 94.28% at high concentration. Under wavelength detection, the sensitivity reaches 0.585nm / %, and the linearity reaches 94.14%. This sensor not only has low cost but also has advantages such as high sensitivity, good repeatability, and wide application range. Among them, in terms of sensitivity detection, compared with other same-type optical fiber sensors, it has a more prominent sensitivity performance in low-concentration detection, has significant advantages, and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the overall structural schematic diagram of the present invention;

[0029] Figure 2 is the three-dimensional structural schematic diagram of the corrosion table module in the present invention;

[0030] Figure 3 is the three-dimensional structural schematic diagram of another angle of the corrosion table module in the present invention;

[0031] Figure 4 is the structural schematic diagram of the optical fiber surface before and after corrosion in the present invention. Among them, Figure 4 Figure a is the structural diagram of the interface surface between the sensing area and the non-sensing area, Figure 4 Figure b is the structural diagram of the sensing area surface, Figure 4 Figure c is the structural diagram of the non-sensing area surface;

[0032] Figure 5 is the performance exploration data diagram of the optical fiber sensor in the present invention. Among them, Figure 5 Figure a is the relationship diagram of intensity and wavelength under different standing times, Figure 5Figure b shows the relationship between the intensity and wavelength of multiple experimental solutions. Figure 5 Figure c shows the relationship between the intensity and wavelength corresponding to different solutes. Figure 5 Figure d shows the relationship between the intensity and wavelength at low concentrations.

[0033] Figure 6 This is the detection data graph of the relationship between the concentration and absorbance of magnesium chloride solution by the fiber optic sensor of the present invention. Among them, Figure 6 Figure a shows the partial enlarged relationship between the intensity and wavelength at different concentrations. Figure 6 Figure b shows the relationship between the absorbance and concentration of magnesium chloride solution. Figure 6 Figure c shows the relationship between the absorbance and concentration of low-concentration magnesium chloride solution. Figure 6 Figure d shows the relationship between the absorbance and concentration.

[0034] Figure 7 This is the detection data graph of the relationship between the concentration and wavelength of magnesium chloride solution by the fiber optic sensor of the present invention. Among them, Figure 7 Figure a shows the relationship between the intensity and wavelength at different concentrations. Figure 7 Figure b shows the partial enlarged view of the intensity and wavelength of magnesium chloride solution. Figure 7 Figure c shows the relationship between the wavelength and concentration of magnesium chloride solution.

[0035] In the figure: 1. Corrosion table main body; 2. Corrosion area; 3. Slot; 4. Optical fiber channel; 5. Lower hole; 6. Waste liquid discharge port; 7. Upper cover; 71. Cover body; 72. Insert block; 73. Insert pin; 74. Upper hole; 8. Lead frame A; 9. Lead frame B; 10. Lead wire hole; 11. Round hole; 12. Sealing insertion plate A; 13. Sealing insertion plate B. Detailed implementation method

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0037] Please refer to Figures 1-3 , the present invention provides a technical solution: a dual-modal multi-region corrosion type fiber optic concentration sensor system based on microfluidics, including:

[0038] The corrosion table module is used to fix the optical fiber and provide a space for corrosion and measurement, and is internally provided with a segmented multi-region corrosion space and a microfluidic fluid channel.

[0039] The fiber optic sensing module uses a single-mode optical fiber to penetrate through the corrosion table module, and its surface is etched with hydrofluoric acid to form multiple segmented sensing regions, which are used to simultaneously detect dual-mode optical signals of light intensity attenuation and wavelength shift;

[0040] The microchannel waste liquid discharge module is connected to each corrosion space of the corrosion table module and is used to discharge the corrosive agent and the waste liquid to be tested;

[0041] The light source is optically connected to one end of the fiber optic sensing module and is used to emit excitation light. The light source can use a tungsten halogen lamp;

[0042] The spectral analysis module is optically connected to the other end of the fiber optic sensing module and is used to synchronously collect dual-mode optical signals of light intensity attenuation and wavelength shift. The spectral analysis module can use an Ocean Optics spectrometer;

[0043] The data processing module is signal-connected to the spectral analysis module and is used to analyze the light intensity and wavelength signals, establish a dual-mode concentration calibration model and output the concentration of the analyte.

[0044] In specific implementation, the corrosion table module is made of polytetrafluoroethylene material. The corrosion table module includes a corrosion table main body 1. The interior of the corrosion table main body 1 is divided into multiple corrosion zones 2 in a segmented manner. At the position corresponding to the corrosion zone 2 on the top of the corrosion table main body 1, a lower hole 5 is opened. A fiber optic channel 4 is horizontally penetrated through the corrosion table main body 1. The fiber optic channel 4 passes through the lower hole 5 and the corrosion zone 2. The top of the corrosion table main body 1 is provided with a detachable upper cover 7. The upper cover 7 includes a cover body 71 and an upper hole 74. The upper hole 74 is opened on the upper surface of the cover body 71 and is coaxially arranged with the lower hole 5 to form a vertical fluid path. The upper hole 74 and the lower hole 5 form the input channel of the microfluidic fluid channel, and the waste liquid discharge port 6 and the connecting pipe form the output channel of the microfluidic fluid channel.

[0045] In specific implementation, at the position corresponding to the lower hole 5 on the top of the corrosion table main body 1, a slot 3 is also opened. At the bottom of the cover body 71, an insertion block 72 is provided, and the upper hole 74 extends from the top of the cover body 71 to the insertion block 72 and is connected to the lower hole 5. The insertion block 72 is inserted into the slot 3 in a matching manner. At the four corners of the cover body 71, insertion feet 73 are provided. The insertion feet 73 are inserted tightly on the outer wall of the corrosion table main body 1. The diameter of the upper hole 74 is smaller than the diameter of the small hole 5. The cover body 71 is fixed on the corrosion table main body 1 through the tight fit of the insertion feet 73, which is convenient for disassembly and assembly. After the cover body 71 is opened, it is convenient to coat the film on the fiber optic sensing area.

[0046] In specific implementation, at the position corresponding to the corrosion zone 2 on the bottom of the corrosion table main body 1, a waste liquid discharge port 6 that is interconnected is also provided. The microchannel waste liquid discharge module is connected to the corrosion zone 2 through the waste liquid discharge port 6. The microchannel waste liquid discharge module includes a connecting pipe, a valve, and a collection bottle that are connected in sequence. One end of the connecting pipe far from the valve is connected to the waste liquid discharge port 6 to facilitate the discharge of waste liquid.

[0047] In a specific implementation, the etching station module also includes a wire rack A8 and a wire rack B9 arranged in an "I" shape on both sides of the etching station body 1. Both ends of the side walls of the wire rack A8 and the wire rack B9 are provided with wire holes 10, and one of the wire holes 10 on the wire rack A8 and the wire rack B9 is connected to the optical fiber channel 4. The top of the wire rack A8 and the side wall of the wire rack B9 are provided with a circular hole 11 connected to the wire hole 10, which can be used to discharge liquid or gas by connecting to a collection bottle or a water pump through a connecting pipe.

[0048] In specific implementation, the corrosion station module also includes multiple groups of seals that can be inserted into the corrosion zone 2 and encapsulated by hot melt adhesive. A through hole is opened in the middle of the seal, and the through hole gradually decreases from top to bottom. The upper surface of the seal is in contact with the optical fiber to form a planar support. This arrangement can ensure the formation of a relatively sealed space on the one hand, and can also support the optical fiber on the other hand.

[0049] In a specific implementation, the sealing member includes a sealing plug plate A12 and a sealing plug plate B13 which can be plugged into each other. The sealing plug plate A12 and the sealing plug plate B13 are respectively inserted into the adapted corrosion zone 2 from both sides of the corrosion platform body 1 .

[0050] In summary, the design of the corrosion platform module reduces external environmental interference and strengthens the protection of the optical fiber sensor; it effectively isolates air flow and external noise interference and improves the anti-interference ability. Through the design of the upper hole 74, the lower hole 5 and the waste liquid discharge port 6, the flow of the test liquid is precisely controlled to make it fully contact with the sensing area and can realize real-time detection of the concentration change of the test liquid. The segmented multi-corrosion zone can fully corrode and the sensing effect is accumulated and superimposed; the multiple segments can provide reliable physical protection for the sensor and further enhance its long-term stability. At the same time, the overall design is small in size, easy to carry, low in cost, easy to prepare, and has a wide range of applications.

[0051] When in use, first remove the coating layer on the surface of the single-mode optical fiber, wipe it with alcohol and deionized water, and clean it with ultrasound to remove surface impurities; then use a fiber optic cutter to cut a 50cm long optical fiber to ensure that the end face is flat and smooth, and pass the single-mode optical fiber through the optical fiber channel 4 of the corrosion platform module and the wire rack A8 and wire rack B9. The two ends of the single-mode optical fiber are welded with the halogen tungsten lamp and the ocean spectrometer interface through a fiber optic fusion machine to ensure the quality of the fusion and avoid defects such as bubbles and cracks. Finally, a complete optical path system is built to connect the light source, spectrometer and computer display to ensure that the components are tightly connected, stable and reliable. Then, a ptfe material conduit is placed at the bottom of the corrosion platform body and connected to the valve. The other end of the valve is directly connected to an acid-resistant and alkali-resistant collection bottle or connected to the collection bottle through a water pump to extract and discharge waste liquids such as hydrofluoric acid. Then, the sealing plug A12 and the sealing plug B13 are inserted into the corrosion zone 2 and encapsulated with hot melt adhesive.

[0052] Then drip 40% hydrofluoric acid solution into the upper hole 74 of each corrosion zone 2, and use the surface tension of the liquid to make the hydrofluoric acid into a spherical shape to evenly corrode the optical fiber. After 35 minutes of corrosion, open the valve and the water pump to suck out the hydrofluoric acid waste liquid, then rinse the optical fiber surface with deionized water to remove residual hydrofluoric acid and corrosion products, and then further clean it with anhydrous alcohol, and finally rinse it with deionized water. Then carry out the second corrosion for 20 minutes, repeat the cleaning steps to ensure that the optical fiber cladding corrosion effect is good and the surface is smooth, and finally obtain a core diameter of about 9μm.

[0053] Then prepare MgCl2 solutions of different concentrations, use an analytical balance to accurately weigh different masses of magnesium chloride powder, dissolve them in deionized water, and prepare a series of solutions of different concentrations (0.0347%, 0.069%, 0.1%, 0.125%, 0.2%, 0.3%, 0.6%, 1.2%, 2.5%, 5%, 10%, 13.5%, 15%, 20%, 25%, 30%, 35%, 40%). Set the spectrometer parameters according to the experimental requirements to keep it in a stable working state, and mix the solutions of different concentrations to be tested. The liquid is injected into the upper hole 74 of the corrosion zone 2 in sequence, so that the solution completely infiltrates the segmented sensing area, and the light intensity attenuation signal and wavelength shift signal of each corrosion zone are synchronously excited and collected through the light source and the spectrum analysis module. The measurement is repeated at least 3 times for each concentration solution, and the average value of the light intensity and wavelength signals is taken to establish a dual-mode calibration curve of light intensity attenuation-concentration and wavelength shift-concentration. The concentration calculation model is obtained by fitting through the data processing module. Finally, the light intensity and wavelength signals of the solution to be tested are input into the calibration model, and the real-time concentration value is output and displayed on a display screen or terminal.

[0054] Furthermore, the surface structure of the optical fiber before and after corrosion is as follows: Figure 4 As shown, in Figure 4 Figure a shows a conical transition between the hydrofluoric acid etched section and the unetched section. Figure 4 Figure b shows that after being etched with 40% hydrofluoric acid for 35 min + 20 min, the diameter of the optical fiber is about 9 μm. Figure 4 Figure c shows the diameter of the uncorroded optical fiber, which is approximately 115 μm.

[0055] Furthermore, the performance of the optical fiber sensor is explored as follows Figure 5 As shown, Figure 5 Figure a shows the relationship between wavelength and light intensity obtained when the optical fiber sensor is placed in air and water for 30 minutes. It can be seen that the light intensity remains almost unchanged after 30 minutes, indicating that our optical fiber sensor has good stability. Figure 5Figure b shows the relationship between optical wavelength and optical intensity of the fiber optic sensor measured in three media: fresh water, 0.0347% magnesium chloride solution, and air. Three sets of measurements were taken for each medium. It can be seen that when the fiber optic sensor repeatedly measures at a certain solution concentration, the finally obtained spectral graph hardly changes. Therefore, the fiber optic sensor has good repeatability; Figure 5 Figure c shows the relationship between optical wavelength and optical intensity obtained by the fiber optic sensor detecting 16% sodium carbonate, 95% alcohol, 30% magnesium chloride, 15% magnesium chloride, and air. It can be seen that the characteristic absorption spectra corresponding to different substances are significantly different. Therefore, this fiber optic sensor has a wide range of applications and can detect the concentrations of different substances; Figure 5 Figure d shows the relationship between optical wavelength and optical intensity obtained by the fiber optic sensor measuring fresh water, 0.0347% magnesium chloride solution, and 0.1040% magnesium chloride solution under the same conditions. It can be seen that when the concentration difference of the same substance is very small, the change in optical intensity in the wavelength band of 650 - 850 nm is relatively significant, and this fiber optic sensor can minimally distinguish a concentration difference of 0.0347%.

[0056] Furthermore, the detection data of the relationship between the concentration of magnesium chloride solution and absorbance by the fiber optic sensor is as Figure 6 shown. Figure 6 Figure a shows the relationship between wavelength and optical intensity corresponding to a series of different concentrations of magnesium chloride solution (from fresh water to 40% magnesium chloride solution). Based on this, a certain formula is substituted to obtain Figure 6 Figure b; Figure 6 Figure b shows Figure 6 the data corresponding to 670 nm in Figure a is extracted. The absorbance corresponding to different concentrations of magnesium chloride solution is obtained through A = lg(I0 / I), and its linear fitting is performed to obtain the linear fitting graph in (b), where y1 represents the linear relationship at low concentrations and y2 represents the linear relationship at high concentrations. And the slopes of y1 and y2 are the sensitivities of this fiber optic sensor to detect the concentration of magnesium chloride solution under optical intensity detection; Figure 6 Figure c is Figure 6 an enlarged view of the low - concentration y1 fitting curve in Figure b of Figure 6 which can more clearly obtain the relationship between low concentration and wavelength;

[0057] Furthermore, the detection data of the relationship between the concentration of magnesium chloride solution and wavelength by the fiber optic sensor is as Figure 7 shown. Figure 7 Figure a shows the relationship between wavelength and concentration of magnesium chloride solution at different concentrations, which is used for Figure 7Analysis of Figure b in the Chinese diagram; Figure 7 Figure b of Figure 7 is a partial enlarged view of the optical wavelength in Figure a of the Chinese diagram at around 800 nm, which describes the optical wavelengths corresponding to the same interference wave valley in different concentrations of magnesium chloride solutions in the wavelength band of around 800 nm. It can be seen from this that as the solution concentration increases, the optical wavelength generally shows a red shift trend; Figure 7 Figure c of Figure 7 is a graph showing the relationship between the concentration of magnesium chloride solution and the wavelength obtained by extracting the data in Figure b of the Chinese diagram, and the fitting curve of y1 is obtained by linear fitting, where the slope of y1 represents the sensitivity of the sensor to the detection of magnesium chloride concentration under wavelength detection.

[0058] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microfluidics-based dual-modal multi-zone corrosion-type optical fiber concentration sensor system, characterized in that, It includes: An etching table module for fixing the optical fiber and providing space for etching and measurement, with a segmented multi-zone etching space and a microfluidic fluid channel inside; An optical fiber sensing module using a single-mode optical fiber to penetrate through the etching table module, and its surface is etched by hydrofluoric acid to form a multi-segment sensing area for simultaneously detecting dual-mode optical signals of light intensity attenuation and wavelength shift; A micro-pipeline waste liquid discharge module connected to each etching space of the etching table module for discharging the etchant and the waste liquid to be measured; A light source optically connected to one end of the optical fiber sensing module for emitting excitation light; A spectral analysis module optically connected to the other end of the optical fiber sensing module for synchronously collecting dual-mode optical signals of light intensity attenuation and wavelength shift; A data processing module signal-connected to the spectral analysis module for analyzing the light intensity and wavelength signals, establishing a dual-mode concentration calibration model and outputting the concentration of the analyte.

2. The dual-mode multi-zone corrosion-type optical fiber concentration sensor system based on microfluidics according to claim 1, wherein: The etching table module is made of polytetrafluoroethylene material. The etching table module includes an etching table main body (1). The interior of the etching table main body (1) is segmented and provided with a plurality of etching zones (2). A lower hole (5) is opened at a position corresponding to the etching zone (2) on the top of the etching table main body (1). An optical fiber channel (4) is transversely penetrated through the etching table main body (1). The optical fiber channel (4) passes through the lower hole (5) and the etching zone (2). A detachable upper cover (7) is provided on the top of the etching table main body (1). The upper cover (7) includes a cover body (71) and an upper hole (74). The upper hole (74) is opened on the upper surface of the cover body (71) and is coaxially arranged with the lower hole (5) to form a vertical fluid path.

3. A dual-modal multi-zone corrosion-based optical fiber concentration sensor system based on microfluidics according to claim 2, characterized in that: A slot (3) is also opened at a position corresponding to the lower hole (5) on the top of the etching table main body (1). An insertion block (72) is provided at the bottom of the cover body (71), and the upper hole (74) extends out of the insertion block (72) from the top of the cover body (71) and communicates with the lower hole (5). The insertion block (72) is inserted into the slot (3) in a matching manner. Insertion feet (73) are provided at the four corners of the cover body (71), and the insertion feet (73) are inserted tightly on the outer wall of the etching table main body (1). The diameter of the upper hole (74) is smaller than the diameter of the small hole (5).

4. A dual-modal multi-zone corrosion-based optical fiber concentration sensor system based on microfluidics according to claim 3, characterized in that: A waste liquid discharge port (6) that is interconnected is also provided at a position corresponding to the etching zone (2) on the bottom of the etching table main body (1). The micro-pipeline waste liquid discharge module is connected to the etching zone (2) through the waste liquid discharge port (6).

5. A dual-modal multi-zone corrosion-based optical fiber concentration sensor system based on microfluidics according to claim 4, characterized in that: The micro-pipeline waste liquid discharge module includes a connecting pipe, a valve, and a collection bottle that are connected in sequence. The end of the connecting pipe away from the valve is connected to the waste liquid discharge port (6).

6. A dual-modal multi-zone corrosion-based optical fiber concentration sensor system based on microfluidics according to claim 5, characterized in that: The upper hole (74) and the lower hole (5) form the input channel of the microfluidic fluid channel, and the waste liquid discharge port (6) and the connecting pipe form the output channel of the microfluidic fluid channel.

7. A dual-mode multi-zone corrosion-type optical fiber concentration sensor system based on microfluidics according to claims 2-6, characterized in that: The corrosion table module further includes a lead frame A (8) and a lead frame B (9) arranged in an "I" shape on both sides of the corrosion table main body (1). Both ends of the side walls of the lead frame A (8) and the lead frame B (9) are provided with wire holes (10), and one wire hole (10) on the lead frame A (8) and the lead frame B (9) is communicated with the optical fiber channel (4). Round holes (11) communicated with the wire holes (10) are provided on the top of the lead frame A (8) and the side wall of the lead frame B (9).

8. A microfluidics-based dual-modal multi-zone corrosion-type optical fiber concentration sensor system according to claim 7, characterized in that: The corrosion table module further includes multiple groups of seals that can be adaptively inserted into the corrosion area (2) and encapsulated by hot melt adhesive. A through hole is provided in the middle of the seal, and the through hole gradually decreases from top to bottom. The upper surface of the seal contacts the optical fiber to form a planar support.

9. A dual-modal multi-zone corrosion-based optical fiber concentration sensor system based on microfluidics according to claim 8, characterized in that: The seal includes a seal plug board A (12) and a seal plug board B (13) that can be inserted into each other. The seal plug board A (12) and the seal plug board B (13) are respectively inserted into the adapted corrosion area (2) from both sides of the corrosion table main body (1).

10. A concentration detection method for a concentration sensor system of a microfluidics-based dual-modal multi-zone corrosion-type optical fiber according to any one of claims 1-9, characterized in that: It includes the following steps: S1. Remove the coating layer on the surface of the single-mode optical fiber, cut it into a preset length after ultrasonic cleaning with alcohol and deionized water, pass the optical fiber through the optical fiber channel (4) of the corrosion table module and the lead frame A (8) and the lead frame B (9), connect the two ends to the light source and the spectral analysis module respectively by a fusion splicer to form a closed optical path, and after inserting the seal plug board A (12) and the seal plug board B (13) into each other in the corrosion area (2), encapsulate them with hot melt adhesive; S2. Drop 40% hydrofluoric acid solution into the upper hole (74) of each corrosion area (2), use the surface tension to form a liquid droplet to cover the surface of the optical fiber, and corrode in two stages. Corrode for 35 minutes in the first stage and 20 minutes in the second stage. After each corrosion, pump and drain the waste liquid through the micro-pipeline waste liquid discharge module, and rinse the corrosion area with deionized water and anhydrous alcohol in sequence; S3. Inject the test solutions with different concentrations into the upper hole (74) of the corrosion area (2) in sequence, make the solution completely wet the segmented sensing area, and synchronously excite and collect the light intensity attenuation signal and wavelength shift signal of each corrosion area through the light source and the spectral analysis module; S4. Repeat the measurement of each concentration solution at least 3 times, take the average value of the light intensity and wavelength signals, establish a dual-mode calibration curve of light intensity attenuation-concentration and wavelength shift-concentration, and obtain a concentration calculation model through fitting by the data processing module; S5. Input the light intensity and wavelength signals of the test solution into the calibration model, output the real-time concentration value, and display it through a display screen or a terminal.

Images