Grating strain sensor monitoring structure

Abstract

The utility model relates to the technical field of grating strain sensors, in particular to a grating strain sensor monitoring structure, which comprises a grating strain sensor body, and the grating strain sensor body sequentially comprises a substrate layer, a buffer transition layer, a grating layer, a temperature compensation layer, a stress isolation layer and a packaging layer from bottom to top. According to the structure of the grating strain sensor body, firstly, a Bragg grating structure based on the photonic crystal fiber is adopted, so that the strain sensitivity of the sensor is greatly improved; due to the unique microstructure of the photonic crystal fiber, the propagation characteristic of light in the fiber is obviously changed, and the interaction between the light and substances is enhanced. When external strain acts on the grating layer, the microstructure change of the photonic crystal fiber is more obvious, and the wavelength and intensity change amplitude of grating reflected light is larger. Compared with a traditional uniform fiber grating strain sensor, the sensitivity of the grating strain sensor is obviously improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to grating strain sensor technical field especially a grating strain sensor monitoring structure. BACKGROUND

[0002] As a kind of key device that mechanical strain is accurately converted into measurable electrical signal or optical signal, strain sensor occupies the pivotal position in modern science and technology field.Piece grating strain sensor is outstanding in strain measurement technology system by virtue of its high precision, high sensitivity and excellent anti-electromagnetic interference characteristics, and becomes the popular choice of scientific research and engineering application.

[0003] Traditional piece grating strain sensor is mainly composed of sensitive monitoring element (grating), substrate and packaging material.The core working principle is based on the strain optical effect of grating, that is, when external strain is applied to grating, the period and refractive index of grating will change, and then the wavelength or intensity of grating diffraction light changes, and the accurate measurement of external strain is realized by accurately detecting the change quantity.In structure layout, grating (sensitive monitoring element) is usually closely attached to the surface of substrate by means of adhesive, and packaging material is surrounded around sensor, which is used to isolate the erosion of external environmental factors to internal sensitive element, and ensure the stable operation of sensor.

[0004] The sensitivity of traditional piece grating strain sensor is mainly restricted by the inherent properties of grating material and the structure parameters of grating.In actual application scene, due to the limitation of existing material performance, it is difficult to further significantly improve the sensitivity of sensor.For example, in the research of cell mechanics in biomedical field, it is necessary to capture extremely small strain change, and the sensitivity of traditional sensor cannot meet this demand. UTILITY MODEL CONTENT

[0005] In view of the technical problem that the sensitivity of traditional sensor is not high, the utility model provides a grating strain sensor monitoring structure.

[0006] The technical scheme adopted by the utility model is: a grating strain sensor monitoring structure, including grating strain sensor body, the grating strain sensor body is from bottom layer to top layer in turn: substrate layer, buffer transition layer, grating layer, temperature compensation layer, stress isolation layer and packaging layer.

[0007] In one of the embodiments, the substrate layer is made of silicon carbide material, the buffer transition layer is made of polyurethane elastomer material, the grating layer adopts grating structure based on photonic crystal fiber, and the stress isolation layer is made of silicone rubber material.

[0008] In one of the embodiments, the temperature compensation layer is made of a gallium-doped silica fiber material matching the thermal expansion coefficient of the grating layer material.

[0009] In one of the embodiments, the encapsulation layer is made of a polyethylene terephthalate material.

[0010] In one of the embodiments, the thickness of the substrate layer is between 500-1000 μm, and the thickness of the buffer transition layer is between 50-100 μm.

[0011] In one of the embodiments, the thickness of the grating layer is between 10-20 μm, and the thickness of the temperature compensation layer is between 30-60 μm.

[0012] In one of the embodiments, the thickness of the stress isolation layer is between 80-150 μm, and the thickness of the encapsulation layer is between 100-200 μm.

[0013] The beneficial effect of the present application is that, compared with the prior art, the grating strain sensor body structure designed in the present application firstly adopts a Bragg grating structure based on a photonic crystal fiber, which greatly improves the strain sensitivity of the sensor. The unique microstructure of the photonic crystal fiber significantly changes the propagation characteristics of light inside the fiber, and the interaction between light and matter is enhanced. When external strain acts on the grating layer, the microstructure of the photonic crystal fiber changes more obviously, resulting in a larger change in wavelength and intensity of the grating reflected light. Compared with the traditional uniform fiber grating strain sensor, the sensitivity of the grating strain sensor in the present application is obviously improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 is a structural schematic diagram of the present application;

[0015] Fig. 2 is a layered structure schematic diagram of the grating strain sensor body in the present application.

[0016] In the figure, the mark is: 1, grating strain sensor body; 11, encapsulation layer; 12, stress isolation layer; 13, temperature compensation layer; 14, grating layer; 15, buffer transition layer; 16, substrate layer. DETAILED DESCRIPTION

[0017] In the description of the utility model, it needs to explain, the term "front", "upper", "lower", "left", "right", "vertical", "horizontal" and so on indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawing, only for the convenience of describing the utility model and simplifying the description, and not indicate or imply that the device or element indicated must have a particular orientation, a particular orientation and operation, therefore, it cannot be understood as a limitation on the utility model.

[0018] In the description of the utility model, it needs to explain, unless otherwise expressly provided and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or it can be detachable connection, or integrally connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0019] The following will be described in detail with the accompanying drawings Figs. 1-2 The utility model is further explained.

[0020] In order to solve the problems in the background art, the present application proposes the following technical scheme: 1, a grating strain sensor monitoring structure, characterized in that, including grating strain sensor body 1, the grating strain sensor body 1 from bottom to top is: base layer 16, buffer transition layer 15, grating layer 14, temperature compensation layer 13, stress isolation layer 12 and packaging layer 11.

[0021] The above technical scheme is explained as follows:

[0022] Base layer 16 material selection: select silicon carbide (SiC) material with high strength, low thermal expansion coefficient and good insulation performance. Silicon carbide has excellent mechanical strength, which can provide stable and reliable support for the upper structure, ensure that the sensor still maintains structural integrity when bearing large external force, and its low thermal expansion coefficient feature makes the size change of the base layer 16 itself very small when the temperature changes, effectively reducing the influence of structural deformation caused by temperature on the measurement accuracy of the sensor. At the same time, good insulation performance can prevent external electromagnetic interference from being conducted to the sensitive element through the base.

[0023] As the basic support structure of the whole sensor, the base layer 16 provides a stable mounting platform for the subsequent functional layers. Its surface is treated by special micro-nano processing to form a micro rough structure, which significantly increases the bonding area and bonding force between the buffer transition layer 15, ensuring that there is no separation or relative displacement between the layers under various complex working conditions, and ensuring the stability of the sensor performance.

[0024] Fabrication Method: Silicon carbide thin film is grown on the substrate material using chemical vapor deposition (CVD) technology. First, the substrate material is placed in a high-temperature reaction furnace, and a mixture of silicon source and carbon source gases, such as silane (SiH4) and methane (CH4), is introduced. In a high-temperature environment, the mixed gas undergoes a chemical reaction, and silicon and carbon atoms are deposited on the substrate surface and gradually grow into a silicon carbide thin film. By precisely controlling the reaction temperature, gas flow, and deposition time, the thickness and quality of the silicon carbide thin film can be accurately controlled. Subsequently, the silicon carbide thin film is patterned using photolithography and etching processes to meet the design requirements of the sensor base layer 16.

[0025] The base layer 16: The base layer 16 serves as the support structure of the entire sensor, and needs to have sufficient strength to withstand external stress and provide stable support for the upper structure. Its thickness is usually between 500-1000μm. A thicker base layer 16 can better resist bending and tensile stress, ensuring the structural integrity of the sensor under complex working conditions. For example, in a vibrating environment during industrial production or under long-term load in civil engineering, a base layer 16 with such thickness can effectively avoid the influence of deformation caused by stress on the performance of the sensor.

[0026] Buffer transition layer 15 material selection: A polyurethane elastomer material with high elastic modulus and good viscoelasticity is used. Polyurethane elastomer has excellent elastic deformation ability and can withstand large external forces without permanent deformation. Its viscoelastic properties enable it to effectively absorb and dissipate energy transmitted from the outside, serving as a buffer and shock absorber.

[0027] The buffer transition layer 15 is located between the base layer 16 and the grating layer 14, and its main function is to uniformly and smoothly transmit the external applied strain force to the grating layer 14. When the sensor is subjected to external mechanical vibration or impact, the polyurethane elastomer can buffer these external forces through its elastic deformation, preventing the grating layer 14 from being directly damaged by excessive impact force. At the same time, its viscoelastic properties can smooth the strain signal transmitted to the grating layer 14 to some extent, reducing noise interference and improving measurement accuracy.

[0028] Fabrication Method: The polyurethane elastomer buffer transition layer 15 is made using the solution casting method. First, polyether polyol, diisocyanate, and chain extender are mixed in a certain proportion and stirred uniformly at an appropriate temperature to form a prepolymer. Then, the prepolymer is poured into a pre-prepared mold that matches the shape of the sensor base layer 16. Under certain temperature and pressure, the prepolymer undergoes crosslinking reaction in the mold to form polyurethane elastomer. After the reaction is completed, the mold is cooled to room temperature, and the polyurethane elastomer buffer transition layer 15 is taken out and polished to ensure better adhesion with the base layer 16 and grating layer 14.

[0029] Buffer transition layer 15: The main function of the buffer transition layer 15 is to buffer external stress and transmit it uniformly to the grating layer 14. Considering its material properties and functional requirements, the thickness is generally designed to be 50-100 μm. This thickness can ensure that the buffer transition layer 15 has sufficient elastic deformation capacity to absorb impact energy, and will not affect the strain transmission efficiency due to excessive thickness. In the field of aerospace, aircrafts will experience various complex vibrations and impacts during flight. The buffer transition layer 15 of this thickness can effectively protect the grating layer 14 from damage caused by instantaneous overload.

[0030] Grating layer 14 material selection: A new grating structure based on photonic crystal fiber (PCF) is adopted. Photonic crystal fiber has a unique microstructure, which contains periodic air holes inside. This structure gives the fiber special optical properties. Compared with traditional optical fibers, photonic crystal fibers can better confine the light field and improve the efficiency of light-matter interaction. In terms of grating fabrication, femtosecond laser direct writing technology is used to write Bragg gratings (FBG) in photonic crystal fibers. Femtosecond laser has extremely high peak power and extremely short pulse width, which can accurately change the refractive index distribution inside the fiber without damaging the main structure of the fiber, forming a high-quality grating structure.

[0031] Grating layer 14 as the core sensitive element of the sensor, its main function is to convert the external strain signal into changes in optical signals. When external strain acts on the grating layer 14, the microstructure of the photonic crystal fiber changes, causing changes in the period and refractive index of the grating, which in turn causes changes in the wavelength and intensity of the reflected light of the grating. By accurately detecting the amount of change in these optical signals, high-precision measurement of external strain can be achieved. Compared with traditional uniform fiber gratings, Bragg gratings based on photonic crystal fibers have wider reflection bandwidth, higher strain sensitivity, and better temperature stability, which can effectively improve the overall performance of the sensor.

[0032] Fabrication method: First, fix the photonic crystal fiber on a high-precision three-dimensional moving platform to ensure the position accuracy of the fiber during processing. Then, use the femtosecond laser beam generated by the femtosecond laser pulse source to focus inside the photonic crystal fiber through the objective lens. By precisely controlling the motion trajectory of the three-dimensional moving platform and the pulse parameters of the femtosecond laser, such as pulse energy, pulse repetition frequency, and pulse width, a Bragg grating with specific period and refractive index modulation is written in the photonic crystal fiber. During the writing process, the reflected spectrum of the grating is monitored in real time, and the processing parameters are adjusted through feedback control to ensure that the performance of the grating meets the design requirements.

[0033] The grating layer 14 is the core sensitive element of the sensor, and its thickness plays a key role in the optical performance and strain response of the sensor. The thickness of the photonic crystal fiber-based grating layer 14 is generally 10-20 μm. A thinner grating layer 14 is beneficial to improve the efficiency of light interaction with matter and enhance the sensitivity of the grating to external strain. In the measurement of cell micro-strain in the biomedical field, such a thin and sensitive grating layer 14 can capture extremely subtle strain changes, providing high-precision data for cell mechanics research.

[0034] Temperature compensation layer 13 material selection: Choose a gallium (Ga) doped silica (SiO2) optical fiber material with a thermal expansion coefficient matching that of the grating layer 14. The thermal expansion coefficient of the gallium-doped silica optical fiber can be adjusted by precisely controlling the doping concentration of gallium, so that it is as close as possible to the thermal expansion coefficient of the photonic crystal fiber. When the temperature changes, the refractive index and length change of the gallium-doped silica optical fiber are similar to those of the photonic crystal fiber, but in the opposite direction.

[0035] The main function of the temperature compensation layer 13 is to eliminate the influence of temperature changes on the measurement results of the grating layer 14. When the ambient temperature changes, the temperature compensation layer 13 and the grating layer 14 both expand or contract due to heat. Because their thermal expansion coefficients are similar and their change trends are opposite, the strain generated by the temperature compensation layer 13 can offset the strain generated by the grating layer 14 due to temperature changes, thereby ensuring that the wavelength and intensity of the grating reflected light are only affected by external mechanical strain, achieving effective compensation for temperature drift. Experimental data show that within a temperature range of -40°C to 120°C, the temperature drift of the sensor designed with the temperature compensation layer 13 is reduced by more than an order of magnitude compared to traditional sensors, greatly improving the measurement accuracy of the sensor in a wide temperature range.

[0036] Manufacturing method: Use chemical vapor deposition (CVD) combined with ion doping technology to make gallium-doped silica optical fiber. First, use CVD technology to deposit a silica preform in a quartz sleeve. During the deposition process, a gas containing a gallium source, such as trimethyl gallium (TMG), is introduced into the reaction chamber, allowing gallium atoms to be uniformly doped into the silica. By precisely controlling the flow rate of the gallium source gas and the deposition time, the doping concentration of gallium can be precisely controlled. Then, the preform is drawn into an optical fiber, and during the drawing process, process parameters such as drawing temperature and speed are controlled to ensure the uniformity of the fiber structure and the stability of the performance. Finally, the drawn gallium-doped silica optical fiber is tested for optical performance, and the fiber that meets the temperature compensation requirements is selected for sensor production.

[0037] The temperature compensation layer 13: The temperature compensation layer 13 needs to work with the grating layer 14 to offset the influence of temperature changes on grating measurement. Its thickness is usually between 30-60 μm. This thickness can ensure that the temperature compensation layer 13 generates sufficient strain to balance the temperature strain of the grating layer 14 when the temperature changes. In high-temperature industrial environments such as steel smelting plants, or low-temperature polar scientific exploration environments, the temperature compensation layer 13 with this thickness range can effectively ensure the measurement accuracy of the sensor within a wide temperature range.

[0038] Stress isolation layer 12 material selection: A silicone rubber material with low Young's modulus and high Poisson's ratio is used. Silicone rubber has good flexibility and elasticity, and its low Young's modulus makes the material deform easily when subjected to external forces, while the high Poisson's ratio ensures that the stress is effectively dispersed when the material is deformed laterally.

[0039] The stress isolation layer 12 is located between the temperature compensation layer 13 and the packaging layer 11, and its main function is to isolate the influence of external stress on the grating layer 14 and the temperature compensation layer 13. When the sensor is subjected to external mechanical stress, the silicone rubber material can absorb and disperse these stresses by deforming itself, avoiding the direct transmission of stress to the grating layer 14 and the temperature compensation layer 13, thereby ensuring the normal operation of the internal sensitive elements of the sensor. In addition, the silicone rubber material also has good chemical corrosion resistance and electrical insulation performance, which can further protect the internal elements from the erosion of external environmental factors.

[0040] Manufacturing method: The silicone rubber stress isolation layer 12 is made by molding. First, the raw silicone rubber is mixed with vulcanizing agents, fillers and other additives in a certain proportion to form a rubber compound. Then, the rubber compound is placed in a mold, and the shape of the mold matches the space between the sensor temperature compensation layer 13 and the packaging layer 11. Under certain temperature and pressure, the rubber compound undergoes vulcanization reaction in the mold to form a silicone rubber stress isolation layer 12 with certain shape and performance. After vulcanization is completed, the mold is cooled to room temperature, the silicone rubber stress isolation layer 12 is taken out, and quality detection is performed to ensure that it is uniform in thickness, free of bubbles and defects.

[0041] The stress isolation layer 12: The stress isolation layer 12 is used to isolate the influence of external stress on the internal sensitive elements. Its thickness is generally between 80-150 μm. A thicker stress isolation layer 12 can better disperse and absorb external stress, protecting the grating layer 14 and the temperature compensation layer 13 from interference. In environments such as mining equipment or large machinery manufacturing workshops that have strong mechanical vibrations, a stress isolation layer 12 with this thickness can ensure stable operation of the sensor.

[0042] Material selection for encapsulation layer 11: Polyethylene terephthalate (PET) material is chosen as the encapsulation layer 11. PET material has excellent mechanical properties, chemical stability, and good optical transparency. Its mechanical properties can provide sufficient protection for the sensor, preventing external physical impact from damaging the internal elements. Chemical stability enables it to resist the erosion of various chemicals, extending the service life of the sensor. Good optical transparency ensures effective encapsulation and protection of internal elements without affecting the optical signal transmission of the grating layer 14.

[0043] As the outermost structure of the sensor, the main function of the encapsulation layer 11 is to protect the internal sensitive elements from external environmental factors such as moisture, dust, and chemicals. At the same time, the encapsulation layer 11 can also enhance the overall mechanical strength of the sensor, improve its reliability and stability in harsh environments. In addition, special coating treatment on the surface of the encapsulation layer 11 can further improve its ultraviolet resistance and wear resistance, expanding the application range of the sensor.

[0044] Manufacturing method: PET encapsulation layer 11 is made by hot pressing. First, cut the PET film into the appropriate size and cover it on the stress isolation layer 12 of the sensor. Then, put the sensor into the hot press, and under certain temperature and pressure, make the PET film tightly adhere to the stress isolation layer 12, and seal the edges of the sensor. After hot pressing, perform an appearance check on the encapsulation layer 11 to ensure that the surface of the encapsulation layer 11 is free of wrinkles, bubbles, and damage, ensuring good encapsulation effect.

[0045] Among them, the encapsulation layer 11: as the outermost protective structure of the sensor, it needs to have good mechanical protection and environmental isolation performance. Its thickness is generally 100-200μm. This thickness can provide sufficient physical protection to prevent external objects from colliding and damaging the internal elements, and effectively block the invasion of moisture, dust, and chemicals. In the application scenarios of outdoor harsh environment monitoring or marine environment, the encapsulation layer 11 with this thickness can significantly prolong the service life of the sensor.

[0046] In further design, the base layer 16 is connected with the buffer transition layer 15: the surface of the base layer 16 is treated with special micro-nano processing to form a micro rough structure, increasing the bonding area with the buffer transition layer 15. When connecting, a high-strength, high-toughness, and good weather-resistant epoxy adhesive is used. First, evenly apply the adhesive on the surface of the base layer 16, then accurately place the buffer transition layer 15 on the base layer 16, and tightly bond them by applying certain pressure and curing at appropriate temperature. This bonding method can ensure that the base layer 16 and the buffer transition layer 15 will not separate or relatively displace under various complex working conditions, ensuring the stability of strain transmission.

[0047] The buffer transition layer 15 is connected with the grating layer 14: since the buffer transition layer 15 adopts polyurethane elastomer material, and the grating layer 14 is based on photonic crystal fiber, the material properties are quite different. Therefore, a silane coupling agent specially designed for the connection of different materials is used as an intermediate medium. The silane coupling agent is first applied on the surface of the buffer transition layer 15 to react with the polyurethane elastomer and form a chemical bond. Then, the pretreated photonic crystal fiber grating layer 14 is placed on the buffer transition layer 15, and under certain temperature and pressure, the silane coupling agent reacts with the hydroxyl groups on the surface of the fiber, realizing the firm connection of the buffer transition layer 15 and the grating layer 14. This connection method not only ensures that the strain can be effectively transmitted from the buffer transition layer 15 to the grating layer 14, but also avoids the problem of unstable connection caused by material differences.

[0048] The grating layer 14 is connected with the temperature compensation layer 13: both the grating layer 14 and the temperature compensation layer 13 are fiber materials, and the connection is made by using fusion technology. A high-precision fiber fusion machine is used to accurately align the end faces of the photonic crystal fiber of the grating layer 14 and the gallium-doped silica fiber of the temperature compensation layer 13, and then high temperature is generated by discharge to melt and fuse the fiber end faces together. During the fusion process, the fusion loss and the alignment of the fiber are monitored in real time to ensure the fusion quality. This fusion method can realize low-loss optical signal transmission, ensure the close cooperation of the temperature compensation layer 13 and the grating layer 14 in optical and mechanical properties, and effectively improve the temperature compensation effect.

[0049] The temperature compensation layer 13 is connected with the stress isolation layer 12: when the gallium-doped silica fiber of the temperature compensation layer 13 is connected with the silicone rubber material of the stress isolation layer 12, a layer of tackifier is first uniformly coated on the surface of the temperature compensation layer 13 to improve the adhesion with the silicone rubber. Then, the liquid silicone rubber material is poured on the surface of the temperature compensation layer 13 and molded by a mold to wrap the temperature compensation layer 13. During the curing process of the silicone rubber, the tackifier reacts with the silicone rubber to form a firm bond. This connection method can effectively isolate the influence of external stress on the temperature compensation layer 13 and the grating layer 14, while ensuring that the function of the temperature compensation layer 13 is not affected.

[0050] The stress isolation layer 12 is connected with the packaging layer 11: when the silicone rubber of the stress isolation layer 12 is connected with the polyethylene terephthalate (PET) material of the packaging layer 11, a hot pressing technology is adopted. A hot melt adhesive film with good compatibility with the PET material is first covered on the surface of the stress isolation layer 12, and then the PET packaging material is covered on the stress isolation layer 12 and is placed in a hot press. Under certain temperature and pressure, the hot melt adhesive film melts and fills in the small gap between the silicone rubber and the PET, and after cooling, a firm connection is formed. This connection mode can enhance the overall mechanical strength of the sensor and improve its reliability and stability in harsh environments.

[0051] In the utility model, the structure of the grating strain sensor body 1 is designed, firstly, the Bragg grating structure based on the photonic crystal fiber is adopted, and the strain sensitivity of the sensor is greatly improved. The unique microstructure of the photonic crystal fiber causes the propagation characteristics of light in the fiber to change significantly, and the interaction between light and matter is enhanced. When external strain acts on the grating layer 14, the microstructure of the photonic crystal fiber changes more obviously, resulting in larger changes in wavelength and intensity of the grating reflected light. Compared with the traditional uniform fiber grating strain sensor, the sensitivity of the grating strain sensor in the utility model is obviously improved; in the biomedical field, the small strain changes generated in the growth and division process of cells can be accurately captured, and more accurate data support is provided for cell mechanics research.

[0052] In addition, during the temperature change process, the thermal expansion coefficients of the temperature compensation layer 13 and the grating layer 14 are matched, and the strains generated by the two are offset, thereby eliminating the influence of temperature on the grating reflected light signal. The polyethylene terephthalate material used in the packaging layer 11 has good electrical insulation performance and can effectively shield external electromagnetic interference. The silicone rubber material of the stress isolation layer 12 can absorb and disperse external mechanical vibration and impact stress, avoiding the influence on the grating layer 14 and the temperature compensation layer 13. At the same time, the Bragg grating based on the photonic crystal fiber has certain immunity to electromagnetic interference, further improving the anti-interference performance of the sensor. In a complex electromagnetic environment, such as a substation, a communication base station and the like, the new sensor can work stably, and the measurement signal is not affected by electromagnetic interference.

[0053] The standard parts used in the utility model can be purchased from the market, and the special-shaped parts can be ordered according to the description and the drawings. The specific connection mode of each part adopts the conventional means such as bolts, rivets and welding in the prior art. The mechanical parts and equipment adopt conventional models in the prior art. The circuit connection adopts the conventional connection mode in the prior art, which will not be described in detail. The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

[0054] While embodiments of the present application have been shown and described, it is to be understood that the scope of the present application is not to be limited by what has been particularly shown and described, and includes modifications and variations in the present application based on the teaching of the present application.

Claims

1. A grating strain sensor monitoring structure, characterized by, The application relates to a grating strain sensor body (1) which comprises, from bottom to top, a substrate layer (16), a buffer transition layer (15), a grating layer (14), a temperature compensation layer (13), a stress isolation layer (12) and a packaging layer (11).

2. A grating strain sensor monitoring structure according to claim 1, wherein, The substrate layer (16) is made of silicon carbide material, the buffer transition layer (15) is made of polyurethane elastomer material, the grating layer (14) adopts a grating structure based on a photonic crystal fiber, and the stress isolation layer (12) is made of silicone rubber material.

3. The grating strain sensor monitoring structure according to claim 1, wherein, The temperature compensation layer (13) is made of gallium-doped silica optical fiber material which matches the thermal expansion coefficient of the grating layer (14).

4. The grating strain sensor monitoring structure of claim 1, wherein, The packaging layer (11) is made of polyethylene terephthalate material.

5. The grating strain sensor monitoring structure according to claim 1, wherein, The thickness of the substrate layer (16) is between 500-1000 mu m, and the thickness of the buffer transition layer (15) is between 50-100 mu m.

6. The grating strain sensor monitoring structure of claim 1, wherein, The thickness of the grating layer (14) is between 10-20 mu m, and the thickness of the temperature compensation layer (13) is between 30-60 mu m.

7. The grating strain sensor monitoring structure of claim 1, wherein, The thickness of the stress isolation layer (12) is between 80-150 mu m, and the thickness of the packaging layer (11) is between 100-200 mu m.

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