Microfluidic-based dual-mode multi-zone corrosion-type fiber-optic concentration sensor

Abstract

The present application relates to the field of photoelectric technology, especially to a dual-mode multi-zone corrosion type optical fiber concentration sensor based on microfluidics, a corrosion platform module for fixing optical fiber and providing corrosion and measurement space, which is internally provided with a segmented multi-zone corrosion space and a microfluidic fluid channel; an optical fiber sensing module, which adopts a single-mode optical fiber penetrating through the corrosion platform module, and a surface of the optical fiber is corroded by hydrofluoric acid to form a multi-segmented sensing area for simultaneously detecting dual-mode optical signals of light intensity attenuation and wavelength shift; and a micro-pipe waste liquid discharge module, which is communicated with each corrosion space of the corrosion platform module. The optical fiber concentration sensor designed by the present application realizes accurate measurement of magnesium chloride solution, has low cost, high sensitivity, good repeatability, wide application range and other advantages, wherein, compared with other same type optical fiber sensors, the sensitivity detection has more outstanding sensitivity performance in low concentration detection, has significant advantages and good application value.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, specifically to a dual-mode multi-region corrosion-type fiber optic concentration sensor based on microfluidics. Background Technology

[0002] Concentration, as a key parameter characterizing the composition and state of matter, has significant research and application value in fields such as biomedicine, environmental monitoring, food safety, and industrial process control. However, traditional concentration detection methods, such as chemical analysis and electrochemical sensors, often suffer from limitations such as cumbersome operation, slow response speed, and difficulty in online monitoring. Furthermore, they require large amounts of chemical reagents and electrical energy, leading to energy waste and environmental pollution. With the rapid development of fiber optic communication technology, researchers 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, and acceleration. In concentration measurement, fiber optic sensing technology has attracted considerable attention from researchers due to its advantages such as high sensitivity, fast response speed, remote measurement capability, corrosion resistance, and small size. Especially in harsh environments such as high temperature, high pressure, and strong electromagnetic interference, fiber optic sensors offer unparalleled advantages. Therefore, research on fiber optic concentration sensors is of significant value for both scientific research and practical applications.

[0003] The sensitivity enhancement of fiber optic concentration sensors is mainly achieved through two strategies: material enhancement and structural enhancement. Material enhancement primarily involves coating the metal with 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),) to improve sensor sensitivity. Structural enhancement, on the other hand, mainly improves the energy attenuation of evanescent waves by using different fiber structures. Existing structures include side-polished fibers, U-shaped fibers, tapered fibers, and photonic crystal fibers. Although fiber optic sensing technology is relatively mature, some limitations still need to be addressed in practical applications. First, the cost is high, the equipment is expensive, and the installation and maintenance process is complex, which increases the overall application cost. Second, it has poor environmental adaptability and is easily affected by temperature fluctuations and mechanical stress, which leads to a decrease in measurement accuracy. Finally, it also has certain shortcomings in response speed, real-time performance, and long-term stability, making it difficult to meet the requirements of some high-demand application scenarios.

[0004] Based on this, we propose a low-cost, high-sensitivity fiber optic concentration sensor that can realize real-time monitoring of the concentration change of the test liquid. Summary of the Invention

[0005] The purpose of this invention is to overcome or at least partially solve the above problems by proposing a microfluidic-based dual-mode multi-zone corrosion fiber optic concentration sensor.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a microfluidic-based dual-modal multi-region corrosion-resistant fiber optic concentration sensor system, comprising:

[0007] The etching stage module is used to fix optical fibers and provide space for etching and measurement. Its interior is equipped with segmented multi-zone etching space and microfluidic fluid channels.

[0008] The fiber optic sensing module uses a single-mode fiber that runs through the etching stage module. Its surface is etched with hydrofluoric acid to form a multi-segment sensing area, which is used to simultaneously detect dual-mode optical signals of light intensity attenuation and wavelength shift.

[0009] The microchannel waste liquid discharge module is connected to each corrosion space of the corrosion stage module and is used to discharge corrosive agent and waste liquid to be tested.

[0010] A light source, connected to one end of the optical path of the fiber optic sensing module, is used to emit excitation light;

[0011] The spectral analysis module is connected to the optical path of the other end of the fiber optic sensing module and is used to synchronously acquire dual-mode optical signals of light intensity attenuation and wavelength shift.

[0012] The data processing module is connected to the spectral analysis module and is used to analyze light intensity and wavelength signals, establish a dual-mode concentration calibration model, and output the concentration of the analyte.

[0013] In a preferred embodiment, the etching stage module is made of polytetrafluoroethylene (PTFE) material. The etching stage module includes an etching stage body, the interior of which is divided into multiple etching zones. A lower hole is opened at the top of the etching stage body corresponding to the etching zone. An optical fiber channel is horizontally arranged through the etching stage body, passing through the lower hole and the etching zone. A detachable upper cover is provided on the top of the etching stage body. 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 provided at the top of the etching stage body corresponding to the lower hole, a plug is provided at the bottom of the cover, and the plug extends from the top of the cover body to communicate with the lower hole. The plug is adapted to be inserted into the slot. Each of the four corners of the cover body is provided with a pin, which is inserted tightly into the outer wall of the etching stage body. The diameter of the upper hole is smaller than the diameter of the lower hole.

[0015] In a preferred embodiment, the bottom of the corrosion stage body is provided with a waste liquid discharge port that is interconnected with the corrosion zone, and the micro-channel waste liquid discharge module is connected to the corrosion zone 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 collection bottle connected in sequence, with the end of the connecting pipe away from the valve connected to the waste liquid discharge port.

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

[0018] In a preferred embodiment, the etching stage module further includes a wire frame A and a wire frame B arranged in an "I" shape on both sides of the etching stage body. Both ends of the side walls of the wire frame A and the wire frame B are provided with wire holes, and one wire hole on the wire frame A and the wire frame B is connected to the optical fiber channel. The top of the wire frame A and the side wall of the wire frame B are provided with circular holes that communicate with the wire holes.

[0019] In a preferred embodiment, the etching stage module further includes multiple sets of sealing elements that can be adapted to be inserted into the etching zone and sealed with hot melt adhesive. The sealing elements have a through hole in the middle, and the through hole gradually decreases in size from top to bottom. The upper surface of the sealing elements is in contact with the optical fiber to form a planar support.

[0020] In a preferred embodiment, the sealing element includes a sealing insert A and a sealing insert B that can be inserted into each other, the sealing insert A and the sealing insert B being inserted into the corresponding corrosion zones from both sides of the corrosion stage body.

[0021] This invention also provides a concentration detection method for a microfluidic-based dual-modal multi-region corrosion-resistant fiber optic concentration sensor system, comprising the following steps:

[0022] S1. Remove the coating layer on the surface of the single-mode fiber, clean it with alcohol and deionized water by ultrasound, cut it to the preset length, pass the fiber through the fiber channel of the etching stage module and the wire frame A and wire frame B, and connect the two ends of the fiber to the light source and the spectral analysis module respectively through the fusion splicer to form a closed optical path. After inserting the sealing plate A and sealing plate B into the etching area, seal them with hot melt glue.

[0023] S2. Drip 40% hydrofluoric acid solution into the upper hole of each corrosion zone, use surface tension to form droplets to cover the surface of the optical fiber, and etch in two stages: the first stage corrosion lasts 35 minutes and the second stage corrosion lasts 20 minutes. After each corrosion, the waste liquid is pumped out through the micro-channel waste liquid discharge module, and the corrosion zone is rinsed with deionized water and anhydrous alcohol in sequence.

[0024] S3. Inject the test solutions of different concentrations into the upper hole of the corrosion zone in sequence, so that the solution completely wets the segmented sensing area, and simultaneously excite and collect the light intensity attenuation signal and wavelength shift signal of each corrosion zone through the light source and the spectral analysis module.

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

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

[0027] Compared with existing technologies, this invention presents a microfluidic-based dual-mode multi-zone corrosion-type fiber optic concentration sensor, which achieves accurate measurement of magnesium chloride solutions. In magnesium chloride solutions ranging from 0% to 40%, the sensor achieves a resolution of 0.0347%. Under intensity detection, its sensitivity reaches 2.0974 / 10 at low concentrations and 4.1 × 10⁻³ / 10 at high concentrations; its linearity reaches 96.74% at low concentrations and 94.28% at high concentrations. Under wavelength detection, its sensitivity reaches 0.585 nm / 10 and its linearity reaches 94.14%. This sensor not only has advantages such as low cost, high sensitivity, good repeatability, and wide applicability, but also exhibits significantly superior sensitivity performance in low-concentration detection compared to other similar fiber optic sensors, demonstrating substantial advantages and good application value. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is a three-dimensional structural diagram of the etching stage module in this invention;

[0030] Figure 3 This is a three-dimensional structural diagram of the etching stage module in this invention from another angle;

[0031] Figure 4 This is a schematic diagram of the optical fiber surface before and after etching, as shown in the present invention. Figure 4 (a) is a diagram of the surface structure at the boundary between the sensing area and the non-sensing area. Figure 4 (b) is a surface structure diagram of the sensing area. Figure 4 (c) is a surface structure diagram of the non-sensing area;

[0032] Figure 5 The graph shows the performance data of the fiber optic sensor of this invention. Figure 5 (a) shows the relationship between intensity and wavelength under different resting times. Figure 5(b) is a graph showing the relationship between solution strength and wavelength in multiple experimental groups. Figure 5 (c) is a graph showing the relationship between intensity and wavelength for different solutes. Figure 5 (d) is a graph showing the relationship between intensity and wavelength at low concentrations;

[0033] Figure 6 This is a graph showing the relationship between the concentration and absorbance of magnesium chloride solution detected by the fiber optic sensor of this invention. Figure 6 (a) is a magnified view of the relationship between intensity and wavelength at different concentrations. Figure 6 (b) is a graph showing the relationship between the absorbance and concentration of magnesium chloride solution. Figure 6 (c) is a graph showing the relationship between absorbance and concentration of a low-concentration magnesium chloride solution. Figure 6 (d) is a graph showing the relationship between absorbance and concentration;

[0034] Figure 7 This is a graph showing the relationship between the concentration and wavelength of magnesium chloride solution detected by the fiber optic sensor of this invention.

[0035] In the diagram: 1. Etching stage body; 2. Etching zone; 3. Slot; 4. Fiber optic channel; 5. Lower hole; 6. Waste liquid discharge port; 7. Top cover; 71. Cover body; 72. Insert block; 73. Insert pin; 74. Top hole; 8. Wire guide A; 9. Wire guide B; 10. Wire hole; 11. Round hole; 12. Sealing insert plate A; 13. Sealing insert plate B. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Please see Figure 1-3 This invention provides a technical solution: a microfluidic-based dual-modal multi-region corrosion-resistant fiber optic concentration sensor system, comprising:

[0038] The etching stage module is used to fix optical fibers and provide space for etching and measurement. Its interior is equipped with segmented multi-zone etching space and microfluidic fluid channels.

[0039] The fiber optic sensing module uses a single-mode fiber through an etching stage module. Its surface is etched with hydrofluoric acid to form a multi-segment sensing area, which is 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 stage module and is used to discharge corrosive agents and waste liquid to be tested.

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

[0042] The spectral analysis module is connected to the optical path of the other end of the fiber optic sensing module. It is used to simultaneously acquire dual-mode optical signals of light intensity attenuation and wavelength shift. The spectral analysis module can be a marine spectrometer.

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

[0044] In specific implementation, the etching stage module is made of polytetrafluoroethylene (PTFE) material. The etching stage module includes an etching stage body 1, which has multiple etching zones 2 arranged in segments inside. A lower hole 5 is opened at the top of the etching stage body 1 corresponding to the etching zone 2. An optical fiber channel 4 is arranged horizontally through the etching stage body 1, passing through the lower hole 5 and the etching zone 2. A detachable upper cover 7 is provided on the top of the etching stage 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. The upper hole 74 and the lower hole 5 form the input channel of the microfluidic fluid channel. The waste liquid discharge port 6 and the connecting pipe form the output channel of the microfluidic fluid channel.

[0045] In specific implementation, a slot 3 is provided at the top of the etching stage body 1 corresponding to the lower hole 5. A plug 72 is provided at the bottom of the cover 71, and the plug 72 extends from the top of the cover 71 through the upper hole 74 and communicates with the lower hole 5. The plug 72 is inserted into the slot 3. A pin 73 is provided at each of the four corners of the cover 71. The pin 73 is inserted into the outer wall of the etching stage body 1. The diameter of the upper hole 74 is smaller than the diameter of the lower hole 5. The cover 71 is fixed to the etching stage body 1 by the insertion and tightening of the pin 73, which can be easily disassembled and assembled. After the cover 71 is opened, it is convenient to apply a thin film to the fiber optic sensing area.

[0046] In specific implementation, the bottom of the corrosion table body 1 and the corresponding position of the corrosion zone 2 are also provided with interconnected waste liquid discharge ports 6. The micro-channel waste liquid discharge module is connected to the corrosion zone 2 through the waste liquid discharge port 6. The micro-channel waste liquid discharge module includes a connecting pipe, a valve and a collection bottle connected in sequence. The end of the connecting pipe away from the valve is connected to the waste liquid discharge port 6 to facilitate the discharge of waste liquid.

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

[0048] In practice, the etching stage module also includes multiple sets of sealing elements that can be adapted to be inserted into the etching zone 2 and sealed with hot melt adhesive. The sealing elements have through holes in the middle, and the through holes gradually decrease in size from top to bottom. The upper surface of the sealing elements contacts the optical fiber to form a planar support. This arrangement ensures the formation of a relatively sealed space on the one hand, and also supports the optical fiber on the other hand.

[0049] In practice, the sealing element includes a sealing insert plate A12 and a sealing insert plate B13 that can be inserted into each other. The sealing insert plate A12 and the sealing insert plate B13 are respectively inserted into the matching corrosion zone 2 from both sides of the corrosion stage body 1.

[0050] In summary, the design of the etching stage module reduces external environmental interference and strengthens the protection of the fiber optic sensor; it effectively isolates airflow and external noise interference, improving anti-interference capabilities. Through the design of the upper hole 74, lower hole 5, and waste liquid discharge port 6, the flow of the test liquid is precisely controlled, ensuring full contact with the sensing area and enabling real-time detection of changes in the concentration of the test liquid. The segmented multi-etching zone ensures thorough etching, and the sensing effect is accumulated and superimposed. The multi-segmentation provides reliable physical protection for the sensor, further enhancing its long-term stability. At the same time, the overall design is small in size, easy to carry, low in cost, easy to manufacture, and has a wide range of applications.

[0051] In use, first remove the coating layer from the surface of the single-mode fiber, wipe it with alcohol and deionized water, and then ultrasonically clean it to remove surface impurities. Next, cut a 50cm length of fiber with a fiber optic cleaver, ensuring a smooth and flat end face. Insert the single-mode fiber through the fiber optic channel 4 of the etching stage module, as well as through conductor frames A8 and B9. Use a fiber optic fusion splicer to connect the fiber to the halogen tungsten lamp and marine spectrometer interfaces at both ends, ensuring splicing quality and avoiding defects such as bubbles and cracks. Finally, build a complete optical path system, connecting the light source, spectrometer, and computer display screen, ensuring tight, stable, and reliable connections for all components. Next, install a PTFE conduit at the bottom of the etching stage body, connecting it to a valve. The other end of the valve is directly connected to an acid- and alkali-resistant collection bottle, or connected to the collection bottle via a water pump, for extracting and discharging waste liquids such as hydrofluoric acid. Then, insert sealing plates A12 and B13 into etching zone 2 and seal them with hot melt adhesive.

[0052] Then, a 40% hydrofluoric acid solution was dripped into the upper hole 74 of each etching zone 2. The surface tension of the liquid caused the hydrofluoric acid to form a spherical shape, uniformly etching the optical fiber. After etching for 35 minutes, the valve and water pump were opened to remove the waste hydrofluoric acid solution. Next, the optical fiber surface was rinsed with deionized water to remove residual hydrofluoric acid and etching products, followed by further cleaning with anhydrous alcohol, and finally rinsed clean with deionized water. A second etching process was then performed for 20 minutes, repeating the cleaning steps to ensure good cladding etching and a smooth surface. The final fiber core diameter was approximately 9 μm.

[0053] Prepare MgCl2 solutions of different concentrations. Using an analytical balance, accurately weigh different masses of magnesium chloride powder and dissolve them in deionized water to prepare a series of solutions with 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 experimental requirements to ensure stable operation. Then, prepare the analyte solutions of different concentrations... The solution is sequentially injected into the upper hole 74 of the corrosion zone 2, so that the solution completely wets the segmented sensing area. The light intensity attenuation signal and wavelength shift signal of each corrosion zone are synchronously excited and collected by the light source and the spectral 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 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 the display screen or terminal.

[0054] Furthermore, the surface structure of the optical fiber before and after etching is as follows: Figure 4 As shown, in Figure 4 (a) indicates a tapered transition between the hydrofluoric acid-corroded section and the uncorroded section; Figure 4 (b) indicates that after etching with 40% hydrofluoric acid for 35 min + 20 min, the diameter of the optical fiber is approximately 9 μm; Figure 4 (c) represents the diameter of the uncorroded optical fiber, which is approximately 115 μm.

[0055] Furthermore, the performance data of this fiber optic sensor are as follows: Figure 5 As shown, Figure 5 (a) describes the relationship between wavelength and light intensity obtained by the fiber optic sensor before and after being left to stand for 30 minutes in air and water, respectively. It can be seen from the graph that the light intensity remains almost unchanged after standing for 30 minutes, which shows that our fiber optic sensor has good stability. Figure 5(b) describes the relationship between light wavelength and light intensity measured by the fiber optic sensor in three media: pure water, 0.0347% magnesium chloride solution, and air. Three sets of measurements were taken for each medium. It can be seen that our fiber optic sensor achieves good repeatability by repeatedly measuring at a certain solution concentration, resulting in a nearly unchanged final spectrum. Figure 5 (c) describes the relationship between light wavelength and intensity obtained by the fiber optic sensor for 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 differ significantly. Therefore, this fiber optic sensor has a wide range of applications and can detect the concentration of different substances. Figure 5 Figure (d) describes the relationship between light wavelength and light intensity obtained by the fiber optic sensor under the same conditions for measuring pure water, a 0.0347% magnesium chloride solution, and a 0.1040% magnesium chloride solution. It can be seen that for the same substance, when the concentration difference is very small, the change in light intensity in the 650-850nm wavelength range is more significant, and this fiber optic sensor can resolve a concentration difference as small as 0.0347%.

[0056] Furthermore, the fiber optic sensor detects data on the relationship between magnesium chloride solution concentration and absorbance, such as... Figure 6 As shown, Figure 6 Figure (a) describes a series of graphs showing the relationship between wavelength and light intensity for different magnesium chloride solution concentrations (from distilled water to 40% magnesium chloride solution). Based on this, a certain formula is used to obtain... Figure 6 (b); Figure 6 (b) describes the process of... Figure 6 The data corresponding to 670 nm in (a) was extracted, and the absorbance of magnesium chloride solutions of different concentrations was obtained by A=lg(I0 / I). A linear fit was then performed to obtain the linear fit graph in (b), where y1 represents the linear relationship at low concentrations and y2 represents the linear relationship at high concentrations. Furthermore, the slopes of y1 and y2 represent the sensitivity of the fiber optic sensor to the concentration detection of magnesium chloride solution under the light intensity detection. Figure 6 (c) is Figure 6 (b) A magnified view of the fitting curve of low concentration y1 can more clearly show the relationship between low concentration and wavelength; Figure 6 (d) shows the relationship between magnesium chloride concentration and light intensity obtained through MATLAB simulation based on theory. The comparison shows that the experimental results are basically consistent with the theoretical analysis.

[0057] Furthermore, this fiber optic sensor can detect data on the relationship between magnesium chloride solution concentration and wavelength, such as... Figure 7 As shown, Figure 7 The leftmost graph depicts the relationship between wavelength and concentration of magnesium chloride solutions of different concentrations, used for... Figure 7 Analysis of the middle plot; Figure 7 The middle image is Figure 7 The leftmost image shows a magnified view of the light wavelength around 800 nm, depicting the light wavelengths corresponding to the same interference trough around 800 nm in magnesium chloride solutions of different concentrations. It can be seen that as the solution concentration increases, the light wavelength generally exhibits a redshift trend. Figure 7 The rightmost picture is... Figure 7 The data extracted from the middle plot shows the relationship between magnesium chloride solution concentration and wavelength. A fitting curve for y1 is obtained through linear fitting, where the slope of y1 represents the sensitivity of the sensor to magnesium chloride concentration detection at the wavelength.

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

Claims

1. A dual-modal, multi-region corrosion-resistant fiber optic concentration sensor system based on microfluidics, characterized in that, Including: The etching stage module is used to fix optical fibers and provide space for etching and measurement. Its interior is equipped with segmented multi-zone etching space and microfluidic fluid channels. The fiber optic sensing module uses a single-mode fiber that runs through the etching stage module. Its surface is etched with hydrofluoric acid to form a multi-segment sensing area, which is used to simultaneously detect dual-mode optical signals of light intensity attenuation and wavelength shift. The microchannel waste liquid discharge module is connected to each corrosion space of the corrosion stage module and is used to discharge corrosive agent and waste liquid to be tested. A light source, connected to one end of the optical path of the fiber optic sensing module, is used to emit excitation light; The spectral analysis module is connected to the optical path of the other end of the fiber optic sensing module and is used to synchronously acquire dual-mode optical signals of light intensity attenuation and wavelength shift. The data processing module is connected to the spectral analysis module and is used to analyze light intensity and wavelength signals, establish a dual-mode concentration calibration model, and output the concentration of the analyte. The etching stage module is made of polytetrafluoroethylene material. The etching stage module includes an etching stage body (1). The etching stage body (1) is divided into multiple etching zones (2) inside. The top of the etching stage body (1) is provided with a lower hole (5) corresponding to the etching zone (2). The etching stage body (1) is provided with a transverse fiber optic channel (4). The fiber optic channel (4) passes through the lower hole (5) and the etching zone (2). The top of the etching stage 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.

2. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 1, characterized in that: The top of the etching platform body (1) is provided with a slot (3) corresponding to the lower hole (5). The bottom of the cover (71) is provided with a plug (72), and the upper hole (74) extends from the top of the cover (71) to the plug (72) and communicates with the lower hole (5). The plug (72) is adapted to be inserted into the slot (3). The four corners of the cover (71) are provided with pins (73). The pins (73) are inserted tightly into the outer wall of the etching platform body (1). The diameter of the upper hole (74) is smaller than the diameter of the lower hole (5).

3. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 2, characterized in that: The bottom of the corrosion platform body (1) is also provided with a waste liquid discharge port (6) that is connected to the corrosion zone (2). The micro-channel waste liquid discharge module is connected to the corrosion zone (2) through the waste liquid discharge port (6).

4. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 3, characterized in that: The micro-channel waste liquid discharge module includes a connecting pipe, a valve and a collection bottle connected in sequence. The end of the connecting pipe away from the valve is connected to the waste liquid discharge port (6).

5. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 4, 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.

6. A microfluidic-based dual-modal multi-region corrosion-type fiber optic concentration sensor system according to any one of claims 1-5, characterized in that: The etching stage module also includes a wire frame A (8) and a wire frame B (9) arranged in the shape of an "I" on both sides of the etching stage body (1). Both ends of the side walls of the wire frame A (8) and the wire frame B (9) are provided with wire holes (10), and one wire hole (10) on the wire frame A (8) and the wire frame B (9) is connected to the optical fiber channel (4). The top of the wire frame A (8) and the side wall of the wire frame B (9) are provided with round holes (11) that communicate with the wire holes (10).

7. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 6, characterized in that: The etching stage module also includes multiple sets of sealing elements that can be adapted to be inserted into the etching zone (2) and sealed with hot melt adhesive. The sealing elements have through holes in the middle, and the through holes gradually decrease in size from top to bottom. The upper surface of the sealing elements is in contact with the optical fiber to form a planar support.

8. The dual-modal multi-region corrosion-type fiber optic concentration sensor system based on microfluidics according to claim 7, characterized in that: The sealing element includes a sealing insert A (12) and a sealing insert B (13) that can be inserted into each other, and the sealing insert A (12) and the sealing insert B (13) are respectively inserted into the matching corrosion zone (2) from both sides of the corrosion stage body (1).

9. A concentration detection method based on a microfluidic-based dual-modal multi-region corrosion-type fiber optic concentration sensor system according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Remove the coating layer on the surface of the single-mode fiber, clean it with alcohol and deionized water by ultrasound, cut it to the preset length, pass the fiber through the fiber channel (4) of the etching stage module and the wire frame A (8) and wire frame B (9), and connect the light source and the spectral analysis module at both ends through the fusion splicer to form a closed optical path. After inserting the sealing plate A (12) and the sealing plate B (13) into the etching area (2), seal it with hot melt glue. S2. Drip 40% hydrofluoric acid solution into the upper hole (74) of each corrosion zone (2), use surface tension to form droplets to cover the surface of the optical fiber, and etch in two stages. The first stage of etching is 35 minutes and the second stage of etching is 20 minutes. After each etching, the waste liquid is pumped out through the micro-channel waste liquid discharge module, and the corrosion zone is rinsed with deionized water and anhydrous alcohol in sequence. S3. Inject different concentrations of the test solution into the upper hole (74) of the corrosion zone (2) in sequence, so that the solution completely wets the segmented sensing area, and excite and collect the light intensity attenuation signal and wavelength shift signal of each corrosion zone simultaneously through the light source and the spectral analysis module. S4. Repeat the measurement at least 3 times for each concentration solution, take the average value of light intensity and wavelength signals, establish a dual-mode calibration curve of light intensity attenuation-concentration and wavelength shift-concentration, and obtain the concentration calculation model by fitting through the data processing module. S5. Input the light intensity and wavelength signals of the solution to be tested into the calibration model, output the real-time concentration value, and display it through the display screen or terminal.

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