A wearable flexible optical fiber hydrogen sensor, hydrogen detection system and method

Abstract

This invention discloses a wearable flexible fiber optic hydrogen sensor, a hydrogen detection system, and a method. The fiber optic hydrogen sensor includes: a flexible wristband with a mounting groove along its length; a fiber optic hydrogen sensor comprising a flexible optical fiber, several tapered fiber segments formed on the flexible optical fiber using a fused ablation process, and a thin-film sensing portion tightly fitted around the tapered fiber segments; the thin-film sensing portion includes, from the inside out, a reflective layer, an excitation layer, a reaction layer, and a catalytic layer; the tapered fiber segments and the thin-film sensing portion constitute a tapered sensing unit; wherein the flexible optical fiber is embedded in the mounting groove, and the thin-film sensing portion protrudes from the mounting groove; and a breathable encapsulation layer is used to encapsulate the opening of the mounting groove. This fiber optic hydrogen sensor ensures both wearing comfort and high sensitivity and stability in hydrogen detection, making it suitable for personal safety monitoring scenarios on the wrist, such as operating hydrogen energy equipment and laboratory research.

Description

Technical Field

[0001] This application relates to the field of hydrogen sensor technology, specifically to a wearable flexible fiber optic hydrogen sensor, a hydrogen detection system, and a method. Background Technology

[0002] With the rapid development of the clean energy industry, hydrogen energy is increasingly being used in portable devices, new energy fields, and scientific research due to its high efficiency and environmental friendliness. However, hydrogen is flammable and explosive, and its leakage may cause safety accidents such as fires and explosions. Therefore, in scenarios where people are in close contact with hydrogen energy, there is an urgent need for a wearable hydrogen detection device that does not interfere with daily activities and can provide real-time warnings.

[0003] Currently, mainstream hydrogen detection equipment is mainly divided into two categories: electrical sensors and fiber optic sensors. Electrical sensors suffer from drawbacks such as susceptibility to electromagnetic interference, low inherent safety, and high power consumption, making them difficult to operate stably in complex environments. While fiber optic sensors offer advantages such as resistance to electromagnetic interference, no electrical sparks, and suitability for long-term monitoring, existing fiber optic sensors mostly employ quartz optical fibers and rigid packaging structures, which are difficult to meet the requirements of wearable devices. For example, Chinese patent CN119827461A discloses a tapered fiber optic hydrogen sensor, which is inflexible and bulky, making it unsuitable for wearable applications.

[0004] Existing wearable hydrogen sensors mostly focus on electrochemical principles, and their detection accuracy is easily affected by factors such as human sweat and environmental humidity, and they also pose a risk of electromagnetic interference. The few wearable hydrogen sensors based on optical fibers cannot simultaneously achieve both "flexible fit" and "detection accuracy." Either the rigidity of the optical fiber leads to discomfort when worn, or the hydrogen-sensitive material is not tightly bonded to the flexible structure, resulting in low detection sensitivity and slow response. Furthermore, most existing wearable hydrogen sensors use Velcro for adjustment to fit different users' wrists, but Velcro tends to loosen with prolonged use. Summary of the Invention

[0005] The purpose of this application is to provide a wearable flexible fiber optic hydrogen sensor, a hydrogen detection system and method. The fiber optic hydrogen sensor of this application can ensure both wearing comfort and high sensitivity and high stability of hydrogen detection.

[0006] On the one hand, this application provides a wearable flexible fiber optic hydrogen sensor, comprising: A flexible wristband having mounting grooves along its length; A fiber optic hydrogen sensor includes a flexible optical fiber, several tapered fiber segments formed on the flexible optical fiber by a fused taper process, and a thin-film sensing unit tightly fitted around the tapered fiber segments. The thin-film sensing unit includes, from the inside out, a reflective layer, an excitation layer, a reaction layer, and a catalytic layer. The tapered fiber segments and the thin-film sensing unit constitute a tapered sensing unit. The flexible optical fiber is embedded in a mounting groove, and the thin-film sensing unit is exposed in the mounting groove. A breathable encapsulation layer is used to encapsulate the opening of the mounting slot.

[0007] Optionally, the number of tapered sensing units is 3 to 5, with a spacing of 1 cm to 3 cm; the length of the tapered fiber section is 100 μm to 200 μm, and the diameter is 3 μm to 5 μm.

[0008] Optionally, the flexible optical fiber has a bend radius of no more than 5 cm and a diameter of 125 μm to 200 μm.

[0009] Optionally, the reflective layer is a chromium-gold double-layer film structure, wherein the Cr layer has a thickness of 5nm~10nm, the Au layer has a thickness of 30nm~45nm, and the total thickness of the reflective layer is 35nm~55nm. The excitation layer is a single-element gold excitation layer with a thickness of 20 nm to 30 nm; the reaction layer is a tungsten oxide-carbon nanotube composite gas-sensitive material reaction layer with a thickness of 15 nm to 20 nm; and the catalytic layer is a single-element platinum catalytic layer with a thickness of no more than 1 nm.

[0010] Optionally, the breathable area on the breathable encapsulation layer is provided with breathable micropores, and the breathable area refers to the area on the breathable encapsulation layer corresponding to the tapered sensing unit.

[0011] Optionally, the flexible wristband has a thickness of 1mm to 2mm and a width of 15mm to 25mm; the breathable sealing layer has a thickness of 50μm to 100μm.

[0012] Optionally, one end of the flexible wristband is provided with a number of buckle holes along its length, and the other end of the flexible wristband is provided with a buckle protrusion that matches the buckle holes; by fastening the buckle protrusion with different buckle holes, the flexible wristband can be adapted to wrists of different sizes.

[0013] Optionally, the inside of the flexible wristband is provided with an anti-slip texture.

[0014] On the other hand, the hydrogen detection system provided in this application includes: The aforementioned wearable flexible fiber optic hydrogen sensor and spectrometer; wherein, the wearable flexible fiber optic hydrogen sensor includes a flexible fiber optic cable, one end of which is connected to the spectrometer via a fiber optic extension line.

[0015] Furthermore, the hydrogen detection method provided in this application, which uses the aforementioned hydrogen detection system for hydrogen detection, includes: The wavelength shift of the SPR resonance peak is extracted from the spectral signal received by the spectrometer. Based on the pre-calibrated linear relationship between the wavelength shift and the hydrogen concentration, the hydrogen concentration corresponding to the extracted wavelength shift is obtained.

[0016] Compared with the prior art, this application has the following advantages and beneficial effects: The fiber optic hydrogen sensor proposed in this application can ensure both wearing comfort and high sensitivity and stability in hydrogen detection, making it suitable for personal safety monitoring scenarios on the wrist, such as operation of hydrogen energy equipment and laboratory scientific research. Attached Figure Description

[0017] The above and other objects, features and advantages of this application will become more apparent from the following description of exemplary embodiments of this application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of this application.

[0018] Figure 1 This is a longitudinal sectional view of the fiber optic hydrogen sensor in the embodiment; Figure 2 This is a cross-sectional view of the fiber optic hydrogen sensor in the embodiment; Figure 3 This is a schematic diagram of the structure of the tapered sensing unit in the embodiment; Figure 4 This is a top view of a portion of the breathable sealing layer in the embodiment; Figure 5 This is a schematic diagram of the anti-slip texture in the embodiment; Figure 6 This is a schematic diagram of the buckling of the flexible wristband in the embodiment.

[0019] Reference numerals: Flexible wristband 100, mounting groove 110, buckle hole 120, buckle protrusion 130, anti-slip texture 140; Fiber optic hydrogen sensor 200, flexible fiber optic 210, tapered sensing unit 220, fiber optic tapered section 221, thin film sensing part 222, reflective layer 222a, excitation layer 222b, reaction layer 222c, catalytic layer 222d; breathable encapsulation layer 300, breathable micropores 310. Detailed Implementation

[0020] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0021] Please see Figures 1-6In this embodiment, the wearable flexible fiber optic hydrogen sensor includes a flexible wristband 100, a fiber optic hydrogen sensor 200, and a breathable encapsulation layer 300. The fiber optic hydrogen sensor 200 is embedded in the flexible wristband 100, and the breathable encapsulation layer 300 is used to encapsulate the fiber optic hydrogen sensor 200.

[0022] Please see Figures 1-2 The flexible wristband 100 is provided with a mounting groove 110 along the length of the flexible wristband 100. The mounting groove 110 is adapted to the fiber optic hydrogen sensor 200, and the fiber optic hydrogen sensor 200 is embedded in the mounting groove 110.

[0023] Please see Figure 3 The fiber optic hydrogen sensor 200 includes a flexible optical fiber 210, on which several tapered fiber segments 221 are arranged. A thin-film sensing element 222 is tightly fitted around each tapered fiber segment 221. The thin-film sensing element 222, from the inside out, includes a reflective layer 222a, an excitation layer 222b, a reaction layer 222c, and a catalytic layer 222d. The tapered fiber segments 221 and the thin-film sensing element 222 constitute a tapered sensing unit 220. The flexible optical fiber 210 is embedded in the mounting groove 110, and the thin-film sensing element 222 protrudes from the mounting groove 110.

[0024] A tapered fiber section 221 is fabricated on the flexible optical fiber 210 using a fused taper process. The unique diameter reduction structure of the tapered fiber section 221 allows more transmitted light inside the optical fiber to penetrate to the outer layer, enhancing the interaction between the optical signal and the hydrogen-sensitive material, thereby amplifying changes in the optical signal and improving detection sensitivity.

[0025] In some embodiments, the tapered fiber section 221 has a length of 100 μm to 200 μm and a diameter of 3 μm to 5 μm. See also... Figure 3 The L indicated represents the length of the fiber tapered section, and the d indicated represents the diameter of the fiber tapered section. The diameter of the fiber tapered section is the outer diameter of the thinnest part of the fiber tapered section.

[0026] In some embodiments, the number of tapered sensing units 220 is 3 to 5, with a spacing of 1 cm to 3 cm between them.

[0027] In some embodiments, the flexible optical fiber 210 has a bending radius of no more than 5 cm, and can be specifically selected as polyimide optical fiber. Compared with traditional quartz optical fiber, polyimide optical fiber has excellent flexibility and is resistant to high temperature and aging. It can withstand human skin temperature and slight sweat corrosion for a long time, thus extending the service life of the sensor.

[0028] Considering that excessively thin optical fibers can lead to high optical signal transmission loss, and excessively thick optical fibers can increase the thickness of the flexible wristband 100, affecting wearing comfort, in some embodiments, the diameter of the flexible optical fiber 210 is preferably 125μm to 200μm.

[0029] The reaction layer 222c is made of gas-sensitive material and is used to react with hydrogen. The catalytic layer 222d is used to catalyze the reaction between the gas-sensitive material and hydrogen. The excitation layer 222b is used to excite the surface plasmon resonance effect on the surface of the optical fiber. When the refractive index of the outer gas-sensitive material changes, the wavelength of the resonance peak shifts significantly, making the change in optical signal easier to detect.

[0030] The excitation layer 222b can be formed on the outer surface of the reflective layer 222a by a vacuum deposition process. In some embodiments, the excitation layer 222b is a single-element gold excitation layer with a thickness of 20 nm to 30 nm.

[0031] The reaction layer 222c can be formed on the outer surface of the excitation layer 222b using a magnetron sputtering process. In some embodiments, the reaction layer 222c is a tungsten oxide-carbon nanotube composite gas-sensitive material reaction layer with a thickness of 15 nm to 20 nm. Tungsten oxide has excellent hydrogen-sensitive properties; when in contact with hydrogen gas, its refractive index changes due to hydrogen atom doping. Carbon nanotubes are used to improve the flexibility and conductivity of the reaction layer 222c, preventing it from detaching or cracking during use; they also accelerate charge transfer and shorten the reaction time.

[0032] The catalyst layer 222d can be formed on the outer surface of the reaction layer 222c by an ultra-thin coating process. In some embodiments, the catalyst layer 222d is a single-element platinum catalyst layer with a thickness of no more than 1 nm. This ultra-thin catalyst layer 222d can avoid blocking hydrogen gas from contacting the reaction layer 222c and does not affect the transmission of optical signals.

[0033] The reflective layer 222a is a chromium-gold double-layer film structure, wherein the Cr layer has a thickness of 5nm~10nm, the Au layer has a thickness of 30nm~45nm, and the total thickness of the reflective layer is 35nm~55nm.

[0034] The reflective layer 222a can be formed on the outer surface of the tapered section 221 of the optical fiber by magnetron sputtering. First, Cr is deposited on the outer surface of the tapered section 221 of the optical fiber, and then Au is deposited. The Cr layer film serves as a transition bonding layer, which can effectively improve the bonding force between the thin film sensing part 222 and the optical fiber, and prevent the thin film sensing part from falling off due to the bending of the optical fiber.

[0035] In this application, the main functions of the reflective layer 222a are as follows: on the one hand, the Au layer film acts as a highly reflective mirror, reflecting the optical signal transmitted to the end face of the optical fiber back to the optical fiber and back to the spectrometer, forming a complete optical path; on the other hand, the reflective layer 222a also plays an isolation and protection role, blocking the mutual diffusion between the thin film sensing part 222 and the optical fiber substrate, improving the long-term stability and mechanical flexibility of the sensor; at the same time, the reflective layer 222a does not participate in the hydrogen reaction, which can ensure the stability of the signal baseline.

[0036] The breathable encapsulation layer 300 is used to encapsulate the fiber optic hydrogen sensor 200, specifically, to encapsulate the opening of the mounting groove 110 to protect and stabilize the fiber optic hydrogen sensor 200. In this application, the breathable encapsulation layer 300 should be breathable, allowing ambient gas to permeate through the breathable encapsulation layer 300 and contact the tapered sensing unit 220, specifically, the thin-film sensing part 222.

[0037] In some embodiments, breathable micropores 310 are distributed on the breathable encapsulation layer 300 in the area corresponding to the tapered sensing unit 220. To ensure rapid permeation of ambient gas while blocking water molecules, the pore size of the breathable micropores 310 is preferably 0.5 μm to 1 μm. For ease of description, the area on the breathable encapsulation layer 300 corresponding to the tapered sensing unit 220 is referred to as the breathable area, and each tapered sensing unit 220 corresponds to one breathable area on the breathable encapsulation layer 300.

[0038] In some embodiments, the breathable area is distributed with breathable micropores 310, and adjacent breathable micropores 310 are spaced 3μm apart to ensure sufficient contact between hydrogen and the tapered sensing unit 220.

[0039] In some embodiments, the breathable encapsulation layer 300 is made of medical-grade flexible silicone with a thickness of 50μm to 100μm.

[0040] In this application, the flexible wristband 100 serves not only as a wearable component but also as the supporting structure for the fiber optic hydrogen sensor 200 and the breathable encapsulation layer 300. To ensure wearing comfort and load-bearing function, the flexible wristband 100 is generally made of medical-grade flexible elastic material, preferably medical-grade silicone rubber; in some embodiments, the thickness of the flexible wristband 100 is preferably 1mm to 2mm, and the width is preferably 15mm to 25mm.

[0041] Furthermore, one end of the flexible wristband 100 is provided with a plurality of buckle holes 120 evenly distributed along its length, and the other end is provided with buckle protrusions 130 adapted to the buckle holes 120; the buckle protrusions 130 are fixed to one end of the flexible wristband and are used to fasten with the buckle holes 120. By fastening the buckle protrusions 130 with different buckle holes 120, the flexible wristband can be adapted to wrists of different sizes.

[0042] In some embodiments, the flexible wristband 100 is 15cm to 25cm long, suitable for the wrist circumference of most adults; the number of buckle holes 120 is 3 to 8, with a spacing of 2mm to 3mm.

[0043] Preferably, an anti-slip texture 140 is provided on the inner side of the flexible wristband 100. The inner side of the flexible wristband 100 refers to the side that contacts the skin of the wrist. The anti-slip texture 140 can be used to increase the friction between the flexible wristband 100 and the skin of the wrist, thereby enhancing the stability when wearing it. In this embodiment, the anti-slip texture 140 is a diamond-shaped anti-slip texture, see Figure 5 As shown, the texture depth is 0.1mm to 0.2mm.

[0044] The working principle of the hydrogen sensor in this application is as follows: Hydrogen permeates through the gas-permeable encapsulation layer 300 and contacts the thin-film sensing part 222 of the tapered sensing unit 220. The catalyst layer 222d accelerates the interfacial reaction between hydrogen and the reaction layer 222c, and hydrogen atoms rapidly dope into the tungsten oxide lattice, causing the refractive index of the reaction layer 222c to change regularly with the hydrogen concentration. That is, the higher the hydrogen concentration, the more hydrogen atoms are doped, and the greater the refractive index shift of the reaction layer 222c. The reduced diameter structure of the tapered section 221 of the optical fiber allows the evanescent wave formed by the light transmitted in the optical fiber to fully penetrate into the excitation layer 222b. The excitation layer 222b can excite the surface plasmon resonance effect on the surface of the optical fiber. The free electrons on the surface of the excitation layer 222b resonate and couple with the evanescent wave to form a specific wavelength SPR resonance peak. When the refractive index of the reaction layer 222c changes with the hydrogen concentration, the interfacial optical properties of the excitation layer 222b and the reaction layer 222c change, resulting in a precise shift in the wavelength of the SPR resonance peak, and the shift is linearly related to the hydrogen concentration. The optical signal with the wavelength shift is transmitted to a portable spectrometer via flexible fiber 210 and flexible fiber extension line, completing the complete conversion link of hydrogen concentration change → refractive index change of reaction layer 222c → SPR resonance peak shift → optical signal output. Example

[0045] This embodiment provides an optical fiber hydrogen sensor.

[0046] In this embodiment, the flexible optical fiber 210 is a 150 μm diameter polyimide flexible optical fiber. Five fiber tapered segments 221 are fabricated on the flexible optical fiber 210 using a fused biconical tapering machine. Each fiber tapered segment 221 is 150 μm long and 4 μm in diameter, with adjacent fiber tapered segments 221 spaced 2 cm apart. Subsequently, a 35 nm thick chromium-gold reflective film, a 25 nm thick elemental gold excitation layer, an 18 nm thick WO3-CNTs composite reaction layer, and a 0.8 nm thick elemental platinum catalyst layer are sequentially deposited on the outer surface of the upper portion of the fiber tapered segment 221 using a vacuum coating machine. The fiber tapered segment 221 and the surrounding chromium-gold reflective film, elemental gold excitation layer, WO3-CNTs composite reaction layer, and elemental platinum catalyst layer constitute the tapered sensing unit 220. In the WO3-CNTs composite reaction layer, WO3 accounts for 85% by mass and CNTs account for 15% by mass.

[0047] The flexible wristband 100 is made of medical-grade silicone rubber. The flexible optical fiber 210 is embedded in the mounting groove 110 on the flexible wristband 100. The breathable area on the breathable encapsulation layer 300 is provided with breathable micropores 310 with a diameter of 0.8μm and a spacing of 3μm. The opening of the mounting groove 110 is encapsulated by the breathable encapsulation layer 300 to obtain the sample of this embodiment. Example

[0048] This embodiment provides a hydrogen detection system, which includes the fiber optic hydrogen sensor prepared in Embodiment 1 and a portable spectrometer. One end of the flexible optical fiber 210 is connected to the fiber optic interface of the portable spectrometer via an optical fiber extension cable. By turning on the portable spectrometer, spectral signals from the fiber optic hydrogen sensor can be received.

[0049] When hydrogen leaks into the environment, the hydrogen comes into contact with the catalytic layer 222d and the reaction layer 222c through the gas-permeable encapsulation layer 300. The catalytic layer 222d accelerates the reaction between the hydrogen and the hydrogen-sensitive material tungsten oxide. The refractive index of the reaction layer 222c changes, and this change is converted into a spectral resonance peak shift through the excitation layer 222b. The shift signal is transmitted to the portable spectrometer via the flexible optical fiber 210 and the optical fiber extension line.

[0050] The offset signal is the wavelength shift of the SPR resonance peak. Based on the linear relationship between the wavelength shift and hydrogen concentration, the hydrogen concentration can be detected from the wavelength shift. In the fiber optic hydrogen sensor of this embodiment, five tapered sensing units 220 are provided, which can receive five sets of wavelength shifts. The average value of the five sets of wavelength shifts is used for hydrogen concentration detection.

[0051] This embodiment further includes configuring the spectrometer to communicate with the smart terminal via a wireless communication module, such as via Bluetooth. The spectrometer converts the received offset signal into an electrical signal, which is then transmitted to the smart terminal via the wireless communication module. The smart terminal then detects and displays the hydrogen concentration based on the offset signal.

[0052] In addition, a safety threshold for hydrogen concentration can be set, such as 0.3% VOL; once the hydrogen concentration is detected to exceed the safety threshold, the smart terminal will issue an alert.

[0053] The following will provide a comparative experiment between the hydrogen detection system of this application and the control group samples.

[0054] The hydrogen detection system in this application uses the fiber optic hydrogen sensor of Example 1, and two control group samples are also provided. The only difference between the control group sample 1 and the sample of Example 1 is that the flexible fiber optic cable 210 does not have the fiber taper section 221. Instead, a 35nm thick chromium-gold reflective film, a 25nm thick elemental gold excitation layer, an 18nm thick WO3 reaction layer, and a 0.8nm thick elemental platinum catalyst layer are sequentially deposited on the surface of the flexible fiber optic cable 210 using a vacuum coating machine. The control group sample 2 is a commercially available flexible electrochemical hydrogen sensor, model TGS2616-C00.

[0055] The following tests were performed on the sample from Example 1, the sample from Control Group 1, and the sample from Control Group 2.

[0056] The flexible fiber optic 210 ends of the sample from Example 1 and the control group 1 were connected to the spectrometer via fiber optic extension cables. The control group 2 sample was connected to a dedicated detection terminal according to its product instructions. Then, the sample from Example 1, the control group 1 sample, and the control group 2 sample were simultaneously placed in a 1 m³ sealed test chamber, maintaining a temperature of 25℃ ± 1℃ and a humidity of 50%RH ± 5%RH within the chamber. Hydrogen was gradually injected using a hydrogen concentration calibrator at concentration gradients of 0.05%VOL, 0.1%VOL, 0.2%VOL, 0.5%VOL, and 1.0%VOL. After stabilizing for 30 minutes at each concentration gradient, the response time, sensitivity, and detection limit of each sample were recorded. The test was repeated three times for each concentration gradient, and the average value was taken.

[0057] The experimental results showed that within the concentration range of 0.05%VOL to 1.0%VOL, the response time of the sample in Example 1 was no more than 120s, the sensitivity reached 0.8nm / %VOL, and the detection limit was as low as 0.03%VOL; for every 0.1% increase in concentration, the resonant peak wavelength shifted stably by about 0.08nm, with a linear correlation coefficient R² = 0.998; the response time of the sample in Control Group 1 was no less than 300s, the sensitivity was only 0.2nm / %VOL, the detection limit was 0.15%VOL, and the linear correlation coefficient R² between concentration change and wavelength shift was 0.921; the response time of the sample in Control Group 2 was 180s to 220s, the sensitivity was 0.1nm / %VOL, the detection limit was 0.08%VOL, and the signal fluctuation amplitude was ±8%.

[0058] The above results show that, compared with the control group sample 1, the sensitivity of the sample in Example 1 can be increased by 4 times, the detection limit can be reduced by 80%, and the response speed is significantly faster and the linear stability is better. At the same time, the detection sensitivity of the sample in Example 1 is also significantly better than that of commercially available flexible electrochemical sensors. The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A wearable flexible fiber optic hydrogen sensor, characterized in that, include: A flexible wristband having mounting grooves along its length; A fiber optic hydrogen sensor includes a flexible optical fiber, several tapered fiber segments formed on the flexible optical fiber by a fused taper process, and a thin-film sensing unit tightly fitted around the tapered fiber segments. The thin-film sensing unit includes, from the inside out, a reflective layer, an excitation layer, a reaction layer, and a catalytic layer. The tapered fiber segments and the thin-film sensing unit constitute a tapered sensing unit. The flexible optical fiber is embedded in the mounting groove, and the thin-film sensing unit is exposed in the mounting groove. A breathable encapsulation layer is used to encapsulate the opening of the mounting slot.

2. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The number of tapered sensing units is 3 to 5, with an interval of 1 cm to 3 cm; the length of the tapered fiber section is 100 μm to 200 μm, and the diameter is 3 μm to 5 μm.

3. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The flexible optical fiber has a bend radius of no more than 5 cm and a diameter of 125 μm to 200 μm.

4. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The reflective layer is a chromium-gold double-layer film structure, wherein the Cr layer film thickness is 5nm~10nm, the Au layer film thickness is 30nm~45nm, and the total thickness of the reflective layer is 35nm~55nm. The excitation layer is a single-element gold excitation layer with a thickness of 20nm to 30nm; The reaction layer is a tungsten oxide-carbon nanotube composite gas-sensitive material reaction layer with a thickness of 15nm to 20nm. The catalyst layer is a single-element platinum catalyst layer with a thickness of no more than 1 nm.

5. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The breathable area on the breathable encapsulation layer has breathable micropores distributed in it. The breathable area refers to the area on the breathable encapsulation layer that corresponds to the tapered sensing unit.

6. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The flexible wristband has a thickness of 1mm to 2mm and a width of 15mm to 25mm; the breathable encapsulation layer has a thickness of 50μm to 100μm.

7. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The flexible wristband has a plurality of buckle holes along its length at one end, and a buckle protrusion adapted to the buckle holes is provided at the other end of the flexible wristband; By engaging the buckle protrusions with different buckle holes, the flexible wristband can be adapted to wrists of different sizes.

8. The wearable flexible fiber optic hydrogen sensor as described in claim 1, characterized in that: The flexible wristband has an anti-slip texture on the inside.

9. A hydrogen detection system, characterized in that, include: The wearable flexible fiber optic hydrogen sensor and spectrometer according to any one of claims 1 to 8; The wearable flexible fiber optic hydrogen sensor includes a flexible optical fiber, one end of which is connected to the spectrometer via an optical fiber extension line.

10. A method for detecting hydrogen, characterized in that: The hydrogen detection system according to claim 9 is used for hydrogen detection, comprising: The wavelength shift of the SPR resonance peak is extracted from the spectral signal received by the spectrometer. Based on the pre-calibrated linear relationship between the wavelength shift and the hydrogen concentration, the hydrogen concentration corresponding to the extracted wavelength shift is obtained.

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