Micro-mirror type optical fiber hydrogen sensor based on gradient tantalum-ruthenium alloy and manufacturing method of micro-mirror type optical fiber hydrogen sensor
By integrating a segmented Ta1-γRuγ composite film on the end face of the optical fiber, the problem of existing optical fiber hydrogen sensors being unable to simultaneously achieve wide range, fast response, and no hysteresis is solved, enabling the detection of hydrogen concentration across seven orders of magnitude and improving the accuracy and applicability of the detection.
Patent Information
- Application Number
- CN202511487066.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-17
- Publication Date
- 2026-01-09
AI Technical Summary
Existing fiber optic hydrogen sensors struggle to simultaneously achieve wide measurement range, fast response, and hysteresis-free operation. Furthermore, the sensor's range is limited by a single sensitive material, making it impossible to meet the demand for wide-range hydrogen concentration detection.
A composite micromirror is constructed by integrating Ta1-γRuγ composite films with different Ru contents in different sections onto the end face of a single optical fiber. These regions include low-ruthenium, medium-ruthenium, and high-ruthenium content areas, which respond to different hydrogen concentration ranges respectively. Through the combined design of a titanium adhesion layer, a catalytic capping layer, and a polymer protective layer, hydrogen concentration detection spanning seven orders of magnitude is achieved.
It achieves an ultra-wide detection range from 10⁻¹ Pa to 10⁶ Pa, with a response time ≤30s and a detection limit of 0.1 Pa. It features high sensitivity and no hysteresis, making it suitable for complex industrial environments. Its compact structure facilitates mass production.
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Figure CN121298596A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fiber optic gas sensing technology, and relates to a micromirror fiber optic hydrogen sensor based on gradient tantalum-ruthenium alloy and its fabrication method. Background Technology
[0002] Hydrogen, as a highly promising clean energy carrier, is increasingly widely used in the energy sector. However, hydrogen is flammable and explosive, with a wide explosive limit range in air, ranging from 4% to 75% (by volume). Within this concentration range, if hydrogen leaks and encounters an ignition source, it can easily cause an explosion, posing a serious threat to life and property. Therefore, accurate and timely detection of hydrogen leaks is crucial to ensuring the safety of hydrogen energy applications.
[0003] Traditional hydrogen detection sensors, such as electrochemical and semiconductor sensors, have many limitations in practical applications. Electrochemical sensors may generate electrical sparks during operation, which undoubtedly increases the risk of explosion in flammable and explosive environments where hydrogen leaks are possible. Semiconductor sensors fail in oxygen-free environments and cannot meet the detection requirements of some special application scenarios. In contrast, fiber optic hydrogen sensors, with their inherent safety, resistance to electromagnetic interference, and corrosion resistance, have become the ideal choice for hydrogen detection. Currently, mainstream fiber optic hydrogen sensor technologies are mainly based on palladium (Pd), palladium alloy, and WO3-based thin films. However, these sensors typically only work effectively within specific hydrogen concentration ranges, such as performing well in the ppm to 4% concentration range. For low-concentration hydrogen (<100ppm), their sensitivity is often insufficient, making it difficult to accurately detect trace amounts of hydrogen leakage; while for high-concentration hydrogen (>10%), the sensor is prone to saturation or irreversible phase transitions. For example, the α-β phase transition of palladium can cause sensor hysteresis and film cracking, seriously affecting the accuracy and reliability of detection. Furthermore, most existing micromirror sensors employ single-component thin-film materials, such as Pd, Pt / WO3, and TaPd. This single-material design severely limits the sensor's measurement range, making it unsuitable for detecting hydrogen concentrations over a wide range.
[0004] To address the shortcomings of the existing technologies, this invention aims to provide a novel micromirror-type fiber optic hydrogen sensor and its fabrication method, effectively solving the technical challenge of existing sensors in achieving a balance between wide range, fast response, and no hysteresis. Summary of the Invention
[0005] In view of this, the purpose of this invention is to provide a micromirror-type fiber optic hydrogen sensor based on gradient tantalum-ruthenium alloy and its fabrication method. By integrating Ta1-γRuγ composite films with different Ru contents in different sections onto the end face of a single optical fiber, a composite micromirror is formed, which breaks through the range limitation of a single sensitive material and achieves wide-range, high-reliability detection of hydrogen concentrations across seven orders of magnitude. This solves the contradiction that existing sensors cannot simultaneously achieve wide range, fast response, and no hysteresis.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A micromirror fiber optic hydrogen sensor based on gradient tantalum-ruthenium alloy includes an optical fiber substrate, a titanium adhesion layer disposed on the end face of the optical fiber substrate, a partitioned tantalum-ruthenium alloy sensing layer disposed on the titanium adhesion layer, a catalytic capping layer disposed on the partitioned tantalum-ruthenium alloy sensing layer, and a polymer protective layer disposed on the catalytic capping layer.
[0008] The partitioned tantalum-ruthenium alloy sensing layer includes at least three independent regions, each with a different ruthenium atom content γ value, to achieve wide-range hydrogen detection.
[0009] Furthermore, the at least three independent regions include a low ruthenium content region, a medium ruthenium content region, and a high ruthenium content region; the γ value of the low ruthenium content region is in the range of 0 to 0.03, responding to a hydrogen partial pressure of 10. -1 ~10 2 Pa; the γ value in the ruthenium content region is in the range of 0.06 to 0.09, responding to a hydrogen partial pressure of 10 Pa. 2 ~10 4 Pa; the γ value in the high ruthenium content region is in the range of 0.12 to 0.15, responding to a hydrogen partial pressure of 10 Pa. 4 ~10 6 Pa.
[0010] Furthermore, the at least three independent regions are arranged in a concentric ring or fan shape, with each independent region having an equal area and a thickness of 30–100 nm; a physical isolation gap is provided between adjacent independent regions, with a gap width of less than 5 μm, to avoid hydrogen diffusion crosstalk.
[0011] Furthermore, the catalytic capping layer is a Pd-Au alloy or a Pd-Au-Cu alloy, with a thickness of 5–15 nm.
[0012] Furthermore, the polymer protective layer is polymethyl methacrylate or polytetrafluoroethylene, with a thickness of 50–200 nm.
[0013] On the other hand, the present invention also provides a method for preparing a micromirror-type fiber optic hydrogen sensor, comprising the following steps:
[0014] S1: After pretreatment of the fiber substrate end face, the titanium adhesion layer is deposited by mask partition sputtering technology;
[0015] S2: Using mask partition sputtering technology, tantalum and ruthenium targets are sputtered on the titanium adhesion layer, the γ value of each independent region is controlled, and the partitioned tantalum-ruthenium alloy sensing layer is deposited;
[0016] S3: Remove the mask and sputter the catalytic capping layer over the entire partitioned tantalum-ruthenium alloy sensing layer;
[0017] S4: Spin-coat or vapor-deposit the polymer protective layer onto the catalytic coating layer, and cure to form the polymer protective layer.
[0018] Furthermore, in steps S2 and S3, the sputtering atmosphere is 1.3 Pa argon gas, and the substrate temperature is controlled at 25±5℃; the tantalum target is pre-sputtered for 120 minutes to remove surface oxides.
[0019] Furthermore, in step S1, the fiber substrate end face is processed to an 8° tilt angle to suppress back reflection.
[0020] On the other hand, the present invention also provides a hydrogen detection system based on the aforementioned micromirror fiber optic hydrogen sensor, comprising the micromirror fiber optic hydrogen sensor, a broadband light source, a spectrometer, and a gas mixing chamber, wherein the broadband light source and the spectrometer are both connected to the micromirror fiber optic hydrogen sensor via a ring coupler, and the micromirror fiber optic hydrogen sensor is arranged in the gas mixing chamber, which has an inlet and an outlet for receiving the detection gas.
[0021] The broadband light source has a wavelength range of 400–800 nm; the spectrometer has a resolution of 0.1 nm; and the system calculates the hydrogen concentration by measuring the shift Δλ / λ0 of the reflection peaks in each independent region.
[0022] Furthermore, the gas mixing chamber is a closed cavity that supports the adjustment of the nitrogen and hydrogen flow ratio to achieve wide-range detection in an oxygen-free environment.
[0023] The beneficial effects of this invention are as follows:
[0024] 1. This invention achieves a hydrogen partial pressure reduction from 10 ppm by integrating a partitioned tantalum-ruthenium alloy sensing layer, a titanium adhesion layer, a catalytic capping layer, and a polymer protective layer on the fiber optic end face. -1 Pa to 10 6 The design achieves an ultra-wide detection range of Pa, spanning seven orders of magnitude. It divides the sensing layer into three independent regions: low ruthenium, medium ruthenium, and high ruthenium, each with an optimized response for a specific hydrogen pyroelectric range (e.g., a response of 10 Pa in the low ruthenium region). -1 ~10 2This allows for monitoring of trace leaks and high-pressure storage and transportation, meeting the needs of all scenarios. Simultaneously, its high sensitivity and hysteresis-free characteristics are prominently displayed: the TaRu alloy exhibits no phase transition hysteresis during hydrogen adsorption, the change in optical reflectance Δλ / λ0 in each region is linearly related to the hydrogen concentration, the response time is ≤30s, and the detection limit reaches 0.1Pa, ensuring measurement accuracy and repeatability, and avoiding the high-concentration saturation or film cracking problems of traditional Pd-based sensors.
[0025] 2. The sensor possesses strong anti-interference capabilities and wide applicability, thanks to its polymer protective layer (such as PMMA or PTFE, with a thickness of 50–200 nm) which effectively blocks interference from humidity, dust, and corrosive gases, preventing performance degradation. Its intrinsically safe design (no risk of electrical sparks) and electromagnetic interference resistance make it suitable for complex industrial environments. Furthermore, its core sensing mechanism relies on hydrogen-induced optical changes, requiring no oxygen, thus performing exceptionally well in oxygen-free environments such as power transformers or nuclear facilities, expanding the application boundaries of traditional sensors.
[0026] 3. Compact structure and ease of mass production are another key advantage: Based on standard single-mode fiber, the probe size is only 125μm, with high integration, facilitating field deployment. Employing mature magnetron sputtering and mask partitioning techniques (such as power ratio-controlled γ value), the fabrication process is simple (completed at room temperature, with pre-sputtering to remove oxides), low in cost, and supports large-scale production. This solution not only improves the safety monitoring efficiency of hydrogen energy facilities but also provides a replicable innovative paradigm for the field of fiber optic gas sensing.
[0027] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description
[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:
[0029] Figure 1 This is a schematic diagram of the structure of a micromirror fiber optic hydrogen sensor based on a gradient tantalum-ruthenium alloy in the embodiment.
[0030] Figure 2 This is a schematic diagram of the partitioned tantalum-ruthenium sensing layer in the embodiment;
[0031] Figure 3 This is a schematic flowchart illustrating a method for fabricating a micromirror fiber optic hydrogen sensor based on a gradient tantalum-ruthenium alloy in an embodiment.
[0032] Figure 4This is a schematic diagram of the test system used for sensor testing in the embodiment.
[0033] Reference numerals: 101 optical fiber substrate, 102 titanium adhesion layer, 103 partitioned tantalum-ruthenium sensing layer, 104 catalytic capping layer, 105 polymer protective layer. Detailed Implementation
[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0035] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.
[0036] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0037] Example 1: Fabrication of a partitioned micromirror fiber optic hydrogen sensor based on gradient tantalum-ruthenium alloy
[0038] like Figures 1-3 This embodiment provides a specific fabrication process for a micromirror-type fiber optic hydrogen sensor. The sensor includes an optical fiber substrate 101, a titanium adhesion layer 102, a partitioned tantalum-ruthenium alloy sensing layer 103, a catalytic capping layer 104, and a polymer protective layer 105. This sensor achieves the ability to detect hydrogen partial pressures from 10... -1 Pa to 10 6Wide range of Pa measurement. The entire preparation process employs magnetron sputtering and spin coating techniques, conducted under standard laboratory conditions, facilitating industrial production.
[0039] Materials preparation:
[0040] Fiber substrate 101: Utilizes Corning SMF-28e single-mode silica fiber with a core diameter of 9μm and a cladding diameter of 125μm. This fiber is resistant to high temperatures and corrosion, making it suitable for fiber optic sensing applications.
[0041] Titanium target: A titanium target with a purity of 99.995% for sputtering titanium adhesion layers.
[0042] Tantalum and ruthenium targets: 99.99% pure tantalum and ruthenium targets are used for co-sputtering partitioned tantalum-ruthenium alloy sensing layers.
[0043] Catalytic target: Pd 0.6 Au 0.4 Alloy target, 99.99% pure, used for sputtering catalytic capping layers.
[0044] Polymer solution: 6 wt% polymethyl methacrylate (PMMA) dissolved in chlorobenzene, used for spin coating protective layer.
[0045] Other auxiliary materials: acetone, ethanol (for cleaning); nitrogen (99.999% purity, used for drying and sputtering atmosphere).
[0046] The preparation steps are as follows:
[0047] S1. Fiber end face pretreatment:
[0048] Take a section of SMF-28e single-mode silica fiber and remove approximately 30 mm of the coating from the end using fiber stripping pliers. Then, use a precision fiber cleaver to cut the fiber end face, creating a flat end face. Next, place the end face on a polishing machine for polishing until the end face roughness Ra < 0.5 nm. After pretreatment, the end face is ultrasonically cleaned in acetone and ethanol for 15 min each, then dried with nitrogen gas and baked in a 120℃ oven for 30 min to remove residual moisture and organic matter.
[0049] This step ensures the fiber end face is clean and free of contamination, providing a good substrate for subsequent deposition. Simultaneously, the fiber end face is fabricated into an 8° tilt micromirror structure to reduce Fresnel back reflection.
[0050] S2. Titanium adhesion layer deposition:
[0051] The pretreated fiber end face was fixed onto the sample stage of the magnetron sputtering equipment. The vacuum chamber was evacuated to 10... -5After Pa, argon gas was introduced as the sputtering atmosphere, with the pressure controlled at 0.30±0.01 Pa. A DC mask-based zoned magnetron sputtering mode was used, with the titanium target power set to 100 W and the substrate temperature maintained at 25±2 °C. The deposition rate was approximately 0.05 nm / s, and deposition was stopped when the thickness reached 4.2±0.3 nm. This titanium adhesion layer 102 enhances the adhesion of subsequent alloy layers to the fiber substrate and prevents peeling.
[0052] S3. Deposition of partitioned tantalum-ruthenium alloy sensing layer:
[0053] In this embodiment, the partitioned tantalum-ruthenium sensing layer 103 is as follows: Figure 2 As shown in the left figure, the geometric configuration adopts a three-concentric ring layout (diameter / ring width precisely controlled by a mask). Specifically, the central region A is circular with a diameter of 20.0±0.5μm and a Ru atomic ratio γA=0.03±0.01; the middle ring region B has an inner diameter of 20μm and an outer diameter of 35±0.5μm, with γB=0.08±0.01; and the outer ring region C has an inner diameter of 35μm and an outer diameter of 50±0.5μm, with γC=0.14±0.01. Each region has a thickness of 40.0±1.0nm, and physical isolation gaps are provided between adjacent independent regions, with the gaps ≤4μm to avoid hydrogen diffusion crosstalk. As another embodiment, the partitioned tantalum-ruthenium sensing layer geometry can adopt a three-part sector layout.
[0054] A partitioned tantalum-ruthenium alloy sensing layer 103 was deposited on the titanium adhesion layer 102 using a mask partitioning technique. First, a central circular mask (20 μm in diameter) was installed to expose the central region A. Then, a tantalum target (125 WDC) and a ruthenium target (4 WDC) were co-sputtered using radio frequency (RF) magnetron sputtering at an argon pressure of 0.30 Pa and a substrate temperature of 25 ± 2 °C. The ruthenium atomic content γA = 0.03 ± 0.01 was monitored in real-time using a quartz crystal oscillator and adjusted by the power ratio. The deposition thickness was 40 μm.
[0055] After deposition, the central mask was removed and a middle ring mask (inner diameter 20 μm, outer diameter 35 μm) was installed to expose the middle ring region B. A tantalum target (125 WDC) and a ruthenium target (8 WDC) were co-sputtered, and γB was adjusted to 0.08 ± 0.01 with a thickness of 40 nm.
[0056] Next, an outer ring mask (inner diameter 35 μm, outer diameter 50 μm) was installed to expose the outer ring region C. A tantalum target (125 WDC) and a ruthenium target (17.5 WDC) were co-sputtered, and γC was adjusted to 0.14 ± 0.01 with a thickness of 40 nm.
[0057] The regions are arranged in concentric rings, with each region having an equal area and a physical gap of ≤4μm between adjacent regions to avoid hydrogen atom diffusion crosstalk. This partitioning design enables the A response in the low ruthenium region to reach 10. -1 ~102 Pa low hydrogen pressure, medium ruthenium region B response 10 2 ~10 4 Pa, hydrogen pressure, high ruthenium region C response 10 4 ~10 6 High hydrogen pressure (Pa) is achieved, covering a range of seven orders of magnitude. Prior to sputtering, the tantalum target is pre-sputtered for 120 minutes to remove surface oxides and ensure alloy purity.
[0058] S4. Catalytic capping layer deposition:
[0059] Remove all masks to expose the entire end face. Deposit Pd globally on the partitioned tantalum-ruthenium alloy sensing layer 103 using DC magnetron sputtering. 0.6 Au 0.4 Alloy target, power 50W, argon pressure 0.3Pa, deposition rate 0.13nm / s. Thickness controlled at 10.2±0.5nm. The catalytic capping layer is 104 (e.g., Figure 1 (As shown) Promotes the dissociation of hydrogen molecules (H2) into active hydrogen atoms (H) on the surface, accelerates the diffusion of hydrogen to the lower sensing layer, and improves the response speed.
[0060] S5. Polymer protective layer coating:
[0061] The sample was placed on a spin coater, and a 6 wt% PMMA / chlorobenzene solution was dropped onto the center of the fiber end face (on the catalytic coating layer). Spin coating parameters: speed 3000 rpm, time 60 s, acceleration 500 rpm / s. Subsequently, the sample was baked on a hot plate at 80±2℃ for 30 min to form a uniform film with a thickness of 150±10 nm. This polymer protective layer 105 blocks interference from environmental humidity, dust, and corrosive gases, ensuring the long-term stability of the sensor.
[0062] After the sensor was fabricated, scanning electron microscopy was used to verify the layer thickness and the clarity of the partition boundaries; Fourier transform infrared spectroscopy was used to confirm the absence of impurities. The entire sensor probe is only 125 μm in diameter, making it compact and portable.
[0063] The sensor operates on the principle that hydrogen molecules dissociate into hydrogen atoms in the catalyst layer, diffuse to the tantalum-ruthenium sensing layer causing lattice expansion and resulting in a change in the material's refractive index. This is ultimately converted into an optical signal via the fiber optic substrate. This design broadens the measurement range through a segmented gradient expansion layer, accelerates the response with an ultra-thin catalyst layer, and eliminates hysteresis with a rigid substrate, achieving a synergistic improvement in the performance of these three elements. A single sensor covers a concentration range of seven orders of magnitude, with a response time ≤30 seconds and a detection limit of 0.1 Pa, making it suitable for safety monitoring of hydrogen energy facilities.
[0064] Example 2: Assembly and Testing of a Hydrogen Detection System
[0065] like Figure 4As shown, this embodiment assembles a hydrogen detection system based on the sensor prepared in Example 1 to verify the sensor's performance. The system includes a micromirror-type fiber optic hydrogen sensor, a broadband light source, a spectrometer, a ring fiber optic coupler, and a gas mixing chamber.
[0066] System assembly:
[0067] Broadband light source: Halogen lamps (wavelength range 400-800nm) are used, coupled to a ring coupler through single-mode optical fiber to separate incident light and reflected light.
[0068] Spectrometer: 0.1 nm resolution, used for real-time acquisition of reflectance spectra, and connected to a ring coupler.
[0069] Gas mixing chamber: It adopts a closed chamber to support the flow ratio of nitrogen (carrier gas) and hydrogen; the incident light emitted by the broadband light source with a wavelength range of 400-800nm is broadband light, which is output through the ring coupler to the micro-mirror fiber optic hydrogen sensor, and the reflected signal is connected to the spectrometer; the gas mixing chamber has an inlet and an outlet for receiving the detection gas.
[0070] Connection method: The sensor probe is inserted into the sealed port of the gas mixing chamber, the end of the optical fiber is connected to the ring coupler, and the reflected signal is introduced into the spectrometer.
[0071] After assembly, nitrogen and hydrogen are thoroughly mixed by controlling the flow rate ratio and then introduced into a sealed gas chamber. The reflectance spectrum of the sensor is measured in real time, and the corresponding hydrogen concentration is calculated based on the reflectance change Δλ / λ0 of each zone.
[0072] According to the formula for the peak wavelength shift of the reflection spectrum: Δλ represents the absolute shift of the peak wavelength, that is, the change in the peak wavelength of the reflected spectrum after hydrogen adsorption relative to the initial peak wavelength. For example, if the initial peak wavelength is λ0, and the peak wavelength becomes λ after hydrogen adsorption, then Δλ = λ - λ0. This change is due to the change in the refractive index of the tantalum-ruthenium alloy sensing layer caused by hydrogen adsorption, which leads to a shift in the optical reflected spectrum. λ0 represents the peak wavelength of the reflected spectrum in the initial state (before hydrogen adsorption), serving as a reference value. It is the peak wavelength measured in a clean air or inert gas environment before the sensor is exposed to hydrogen. Therefore, Δλ / λ0 is a normalized relative wavelength shift, representing the relative proportion of the wavelength change. This normalization eliminates the influence of absolute wavelength values, improves the stability and reliability of measurements, and reduces interference caused by light source fluctuations or system errors. In the sensor, by measuring this ratio and combining it with calibration parameters (constants fitted through calibration experiments) α and β, the hydrogen pressure can be accurately calculated. To achieve quantitative detection.
[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A micromirror-type fiber optic hydrogen sensor based on a gradient tantalum-ruthenium alloy, characterized in that, It includes an optical fiber substrate, a titanium adhesion layer disposed on the end face of the optical fiber substrate, a partitioned tantalum-ruthenium alloy sensing layer disposed on the titanium adhesion layer, a catalytic capping layer disposed on the partitioned tantalum-ruthenium alloy sensing layer, and a polymer protective layer disposed on the catalytic capping layer. The partitioned tantalum-ruthenium alloy sensing layer includes at least three independent regions, each with a different ruthenium atom content γ value, to achieve wide-range hydrogen detection.
2. The micromirror-type fiber optic hydrogen sensor according to claim 1, characterized in that, The at least three independent regions include a low ruthenium content region, a medium ruthenium content region, and a high ruthenium content region; the γ value of the low ruthenium content region is in the range of 0 to 0.03, responding to a hydrogen partial pressure of 10. -1 ~10 2 Pa; the γ value in the ruthenium content region is in the range of 0.06 to 0.09, responding to a hydrogen partial pressure of 10 Pa. 2 ~10 4 Pa; the γ value in the high ruthenium content region is in the range of 0.12 to 0.15, responding to a hydrogen partial pressure of 10 Pa. 4 ~10 6 Pa.
3. The micromirror-type fiber optic hydrogen sensor according to claim 2, characterized in that, The at least three independent regions are arranged in a concentric ring or fan shape, with each independent region having an equal area and a thickness of 30–100 nm; a physical isolation gap with a gap width of less than 5 μm is provided between adjacent independent regions to avoid hydrogen diffusion crosstalk.
4. The micromirror-type fiber optic hydrogen sensor according to claim 1, characterized in that, The catalytic capping layer is a Pd-Au alloy or a Pd-Au-Cu alloy, with a thickness of 5–15 nm.
5. The micromirror-type fiber optic hydrogen sensor according to claim 1, characterized in that, The polymer protective layer is made of polymethyl methacrylate or polytetrafluoroethylene, with a thickness of 50–200 nm.
6. A method for fabricating a micromirror-type fiber optic hydrogen sensor according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: After pretreatment of the fiber substrate end face, the titanium adhesion layer is deposited by mask partition sputtering technology; S2: Using mask partition sputtering technology, tantalum and ruthenium targets are sputtered on the titanium adhesion layer, the γ value of each independent region is controlled, and the partitioned tantalum-ruthenium alloy sensing layer is deposited; S3: Remove the mask and sputter the catalytic capping layer over the entire partitioned tantalum-ruthenium alloy sensing layer; S4: Spin-coat or vapor-deposit the polymer protective layer onto the catalytic coating layer, and cure to form the polymer protective layer.
7. The preparation method according to claim 6, characterized in that, In steps S2 and S3, the sputtering atmosphere is 1.3 Pa argon gas, and the substrate temperature is controlled at 25±5℃; the tantalum target is pre-sputtered for 120 minutes to remove surface oxides.
8. The preparation method according to claim 6, characterized in that, In step S1, the fiber substrate end face is processed to an 8° tilt angle to suppress back reflection.
9. A hydrogen detection system based on the micromirror-type fiber optic hydrogen sensor according to any one of claims 1 to 5, characterized in that, The device includes a micromirror-type fiber optic hydrogen sensor, a broadband light source, a spectrometer, and a gas mixing chamber. The broadband light source and the spectrometer are connected to the micromirror-type fiber optic hydrogen sensor via a ring coupler. The micromirror-type fiber optic hydrogen sensor is arranged in the gas mixing chamber, which has an inlet and an outlet for receiving the detection gas. The broadband light source has a wavelength range of 400–800 nm; the spectrometer has a resolution of 0.1 nm; the system calculates the hydrogen concentration by measuring the shift Δλ / λ0 of the reflection peaks in each independent region.
10. The hydrogen detection system according to claim 9, characterized in that, The gas mixing chamber is a sealed cavity that supports the adjustment of the nitrogen and hydrogen flow ratio to achieve wide-range detection in an oxygen-free environment.