Photo-thermal effect-based light-driven sensing integrated flexible joint and light path system thereof

Abstract

The invention discloses a photo-thermal effect-based light-driven sensing integrated flexible joint and a light path system thereof, the flexible joint comprises a multimode fiber and a photo-thermal conversion elastomer, the photo-thermal conversion elastomer is in an arc-shaped joint shape, the photo-thermal conversion elastomer contains a material for photo-thermal conversion, and the material for photo-thermal conversion is a material for photo-thermal conversion. The multimode optical fiber is eccentrically embedded in the photothermal conversion elastomer; a fiber bragg grating is engraved on a fiber core of the multimode fiber, and the midpoint of the fiber bragg grating is flush with the midpoint of the flexible joint; when the incident light power of the multimode optical fiber is increased, the photothermal conversion elastomer bends towards the curvature reduction direction, and the reflection spectrum signal of the fiber bragg grating reflects the change angle of the photothermal conversion elastomer. According to the invention, sensing and driving functions are integrated by using the fiber Bragg grating, and the device has the advantages of high integration, low energy loss, small size, light weight, interference resistance and the like, and is conveniently applied to soft robots, in-vivo operations, high radiation, flammable and explosive occasions and the like.

Description

Technical Field

[0001] The present invention relates to the field of flexible robots, and in particular to a light-driven sensing integrated flexible joint and an optical path system thereof. Background Art

[0002] In the field of flexible robots, most flexible actuators only have actuation functions, lack real-time perception feedback, and have single functions. The addition of additional perception devices will make the structure complicated, increase the volume, and reduce reliability.

[0003] Existing flexible robots are mostly driven by air pressure or hydraulic pressure, which requires large and bulky power source equipment to complete the drive, and has problems such as high energy consumption and poor flexibility. During use, the life of the pressure cylinder flexible body becomes very limited due to frequent expansion and contraction, and hydraulic oil leakage can easily cause environmental pollution; for pneumatic equipment, it is easy to have faults such as air leakage due to excessive use.

[0004] For some flexible joints that use reduced graphene oxide as the deformable material to generate thermal drive and utilize its conductivity to integrate a sensor network, their sensor network adopts electrical principles and is exposed on the outer layer of the body. They are easily affected by the adverse effects of the working environment, have poor anti-interference ability, large power loss caused by resistance, and electric heat affecting control accuracy, making them easily damaged.

[0005] At present, there is a type of soft robot that embeds components for sensing, driving, computing, power storage and communication in soft materials. The components are complicated, and most of them embed rigid joints into soft materials to achieve continuous flexible movement. There are also some that use tension fibers or fluid elastomers as artificial tendons to achieve movement. The above defects are that each component has a single function, resulting in a complex device structure, low reliability and high cost. Summary of the invention

[0006] The main purpose of the present invention is to provide a light-driven and sensed integrated flexible joint based on photothermal effect and its optical path system, which can realize the design of a highly integrated drive-sensing integrated light-driven flexible joint and complete the drive-sensing integrated joint movement with a streamlined structure.

[0007] The technical solution adopted by the present invention is:

[0008] Provided is a light-driven sensing integrated flexible joint based on photothermal effect, comprising a multimode optical fiber and a photothermal conversion elastomer, wherein the photothermal conversion elastomer is in an arc-shaped joint shape, the photothermal conversion elastomer contains a material for photothermal conversion, and the multimode optical fiber is eccentrically embedded in the photothermal conversion elastomer;

[0009] A fiber Bragg grating is engraved on the core of the multimode optical fiber, and the midpoint of the fiber Bragg grating is flush with the midpoint of the flexible joint;

[0010] When the incident light power of the multimode optical fiber increases, the photothermal conversion elastomer will bend in the direction of decreasing curvature, and the reflection spectrum signal of the fiber Bragg grating reflects the changing angle of the photothermal conversion elastomer.

[0011] According to the above technical solution, the multimode optical fiber is embedded in a position close to the large radius side of the arc-shaped joint of the photothermal conversion elastomer.

[0012] According to the above technical solution, the material used for photothermal conversion is gold nanoparticles, carbon nanotubes or graphene oxide powder having photothermal effect.

[0013] According to the above technical solution, the reflection peak wavelength range of the fiber Bragg grating is 1550-1630nm, the length is 1-15mm, and the reflectivity is at least 90%.

[0014] According to the above technical solution, the multimode optical fiber is in an eccentric state inside the photothermal conversion elastomer, and the eccentricity ranges from 0 to 375 μm. The actuation effect of the flexible joint becomes better as the eccentricity increases.

[0015] According to the above technical solution, the material of the photothermal conversion elastomer is a material with a large thermal expansion coefficient and a small specific heat capacity.

[0016] According to the above technical solution, the material of the photothermal conversion elastomer includes but is not limited to epoxy resin or polyimide plastic.

[0017] According to the above technical solution, the multimode optical fiber and the photothermal conversion elastomer have different thermal expansion coefficients. When the temperature changes, the photothermal conversion elastomer bends due to the unbalanced thermal stress generated inside.

[0018] Following the above technical solution, a cladding layer and a coating layer are further provided outside the core of the multimode optical fiber, wherein the core diameter is 105 μm, the cladding diameter is 125 μm, and the coating diameter is 250 μm.

[0019] The present invention also provides an optical path system of an optically driven, sensing integrated flexible joint, comprising a flexible joint, a 1*3 optical splitter, a high-power laser and a sensor component, wherein the sensor component comprises a tunable laser, an optical power meter and an optical isolator, the high-power laser is connected to the first branch port of the 1*3 optical splitter; the input end of the optical isolator is connected to the tunable laser, and the output end of the optical isolator is connected to the second branch port of the 1*3 optical splitter; the optical power meter is connected to the third branch port of the 1*3 optical splitter, and the flexible joint is connected to the combining port of the 1*3 optical splitter, wherein the flexible joint is the optically driven, sensing integrated flexible joint based on the photothermal effect as described in the above technical solution.

[0020] The beneficial effects of the present invention are as follows: the present invention utilizes a fiber Bragg grating to realize the bending curvature sensing of a flexible joint, and eccentrically embeds a multimode optical fiber into a photothermal conversion elastomer, and the photothermal conversion elastomer contains a material capable of photothermal conversion. Under the irradiation of a laser, the flexible joint produces a temperature change, and the eccentric structure composed of the photothermal conversion elastomer and the multimode optical fiber will produce a bending deformation due to the temperature change. The fiber Bragg grating has good linearity and high sensitivity to the change of strain and temperature, and can fully meet the real-time monitoring of the joint state. The present invention utilizes a fiber Bragg grating to integrate the sensing and driving functions, and has the advantages of high integration, low energy consumption, simple structure, small size, light weight, and anti-interference, and is convenient for application in soft robots, in vivo surgery, high radiation, flammable and explosive occasions, and the like.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 Schematic diagram of the flexible joint structure of an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of an optical path system according to an embodiment of the present invention.

[0025] Figure 3 Schematic diagram of a 1*3 optical splitter according to an embodiment of the present invention.

[0026] Figure 4 FIG. 4 is a schematic diagram of an optical isolator according to an embodiment of the present invention.

[0027] Figure 5 Schematic diagram of the working state of the flexible joint according to an embodiment of the present invention.

[0028] The components in the figure are numbered as follows:

[0029] 1. Flexible joint; 2. Multimode optical fiber; 3. Photothermal conversion elastomer; 4. Coating; 5. Cladding; 6. Fiber core; 7. Fiber Bragg grating; 8. High power laser; 9. Tunable laser; 10. Optical power meter; 11. Optical isolator; 12. 1*3 optical splitter; 13. Sensor component. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] It should be noted that the illustrations provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0032] In the present invention, it is also necessary to explain that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, if the terms "first" and "second" appear, they are only used for description and distinction purposes, and cannot be understood as indicating or implying relative importance.

[0033] This light-driven flexible joint integrates the sensing and driving functions by using multimode optical fiber, adopts a new light energy driving method to realize the bending movement of the flexible joint, and uses a fiber Bragg grating to realize the bending curvature sensing of the flexible joint. The multimode optical fiber is eccentrically embedded in the photothermal conversion elastomer, and the photothermal conversion elastomer contains a photothermal conversion material. Under the irradiation of the laser, the flexible joint produces a temperature change, and the eccentric structure composed of the photothermal conversion elastomer and the multimode optical fiber will bend and deform due to the temperature change. The present invention integrates the sensing and driving functions by using a fiber Bragg grating, and has the advantages of high integration, low energy consumption, simple structure, small size, light weight, anti-interference, etc., and is easy to be used in soft robots, in vivo surgery, high radiation, flammable and explosive occasions, etc.

[0034] Fiber Bragg grating is small in size. As part of the deformable structure, it integrates the sensing function while meeting the needs of achieving joint movement, realizing the design of highly integrated drive-sensing integrated optically driven flexible joints, and completing joint movement with drive-sensing integration in a streamlined structure. In addition, fiber Bragg grating has good linearity and high sensitivity to changes in strain and temperature, which can fully meet the real-time monitoring of joint status.

[0035] like Figure 1As shown, the light-driven sensing integrated flexible joint 1 based on the photothermal effect of this embodiment includes a multimode optical fiber 2 and a photothermal conversion body elastomer 3, wherein the photothermal conversion elastomer 3 is in the shape of an arc joint, the photothermal conversion elastomer 3 contains materials for photothermal conversion, and the multimode optical fiber 2 is eccentrically embedded in the photothermal conversion elastomer 3; a fiber Bragg grating 7 is engraved on the core of the multimode optical fiber 2, and the midpoint of the fiber Bragg grating 7 is flush with the midpoint of the flexible joint 1; when the incident light power of the multimode optical fiber 2 increases, the photothermal conversion elastomer 3 will bend in the direction of decreasing curvature, and the reflection spectrum signal of the fiber Bragg grating 7 reflects the change angle of the photothermal conversion elastomer 3. There is an eccentricity e between the axis of the multimode optical fiber 2 and the axis of the flexible joint 1. The range of the eccentricity e is 0 to 375 μm. When the eccentricity e takes a larger value, the flexible joint 1 can obtain a better actuation effect. In the initial state, the flexible joint 1 has a certain bending amount, and the bending radius is R. In the working state, as the incident light power to the flexible joint 1 increases, the flexible joint 1 will bend in the direction of decreasing curvature. During the movement, the reflection spectrum signal of the fiber Bragg grating 7 reflects the change of the angle of the flexible joint 1.

[0036] Multimode optical fiber 2 is selected as the medium for energy transmission, and quartz optical fiber can be used. Multimode optical fiber 2 includes coating layer 4, cladding layer 5, and core 6 from outside to inside, and fiber Bragg grating 7 is engraved in the core 6 of multimode optical fiber 1. In one embodiment of the present invention, the core diameter is 105μm, the cladding diameter is 125μm, the coating diameter is 250μm, and the numerical aperture is 0.15±0.02. When preparing the flexible joint 1, the position of the mold and the multimode optical fiber 2 can be adjusted so that the midpoint of the fiber Bragg grating 7 is flush with the midpoint of the flexible joint 1.

[0037] Specifically, the fiber Bragg grating 7 can be written on the multimode optical fiber 2 using femtosecond laser technology, with a reflection peak wavelength range of 1550-1630 nm, a length of 1-15 mm, and a reflectivity of not less than 90%.

[0038] The materials used for the photothermal conversion elastomer include, but are not limited to, epoxy resin, polyimide plastic, and other materials with a large thermal expansion coefficient and a small specific heat capacity. When the specific heat capacity of the material used is small, the movement reaction speed of the flexible joint 1 is faster; if the thermal expansion coefficient of the material is high, its volume change is more significant when the temperature changes, which can bring greater driving force. In a preferred embodiment of the present invention, the thermal expansion coefficients of the multimode optical fiber 2 and the photothermal conversion elastomer 3 inside the flexible joint 1 are different. When the temperature changes, unbalanced thermal stress is generated inside the flexible joint 1, causing the flexible joint 1 to bend.

[0039] The materials used for the photothermal conversion particles embedded in the photothermal conversion elastomer 3 include, but are not limited to, gold nanoparticles, carbon nanotubes, graphene oxide powder and other materials with photothermal effect.

[0040] In one embodiment of the present invention, the matrix material of the photothermal converter elastomer 3 is epoxy resin, and the photothermal converter material is graphene powder. To prepare the flexible joint 1, it is first necessary to prepare the photothermal converter elastomer 3 material solution: in a preferred embodiment, 5g of epoxy resin B component curing agent can be added to a 100mL beaker, followed by adding 1g of graphene powder, stirring for the first time with a glass rod, and then adding 15g of epoxy resin A component resin for stirring. After pouring the reagent into a centrifuge tube, place it in a centrifuge for centrifugation, adjust the centrifuge speed to 5000rpm / min, and mix the components evenly by centrifugation for 5 minutes. Then use an ultrasonic instrument to ultrasonically disperse the graphene powder so that the graphene powder is evenly mixed in the epoxy resin solution, and then the solution is placed in a vacuum machine to remove bubbles in the reagent using negative pressure.

[0041] A capillary silicone tube with an inner diameter of 0.3 to 1 mm, a length of 4 to 6 cm and easy to peel off can be used as a filling mold for the photothermal conversion elastomer (3); a metal octagonal prism with a side length of 0.5 to 1.2 cm is used as a fixed mold during the thermal curing process of the flexible joint 1 to ensure that the eccentricity of the multimode optical fiber 2 in the flexible joint 1 reaches the maximum value. Using vacuum defoaming or centrifugal defoaming technology before filling the photothermal conversion elastomer 3 material solution can greatly reduce product defects after thermal curing molding.

[0042] In a preferred embodiment of the present invention, a syringe with a pinhole diameter of 0.45 mm is used to inject the above-mentioned photothermal conversion elastomer 3 material solution into a silicone tube through which a multimode optical fiber 2 is inserted (the silicone tube has a length of 60 mm, an outer diameter of 1.6 mm, and an inner diameter of 0.6 mm. The inner wall needs to be cleaned in advance, and the multimode optical fiber 2 also needs to be cleaned of surface dust with alcohol in advance to improve the bonding ability between the multimode optical fiber 2 and the epoxy resin, until the reagent fills the entire silicone tube, and the fiber Bragg grating 7 is adjusted to be located in the middle of the silicone tube. It should be noted that the multimode optical fiber 2 must have a length of at least 40 mm after passing through the silicone tube. Then, the silicone tube is wound and fixed on the octagonal prism mold (the mold side length is 5mm and the length is 100mm). This ensures that the multimode optical fiber 2 is eccentrically restricted to the large radius end of the flexible joint 1. The preset bending diameter of the flexible joint 1 can reach 20mm. Then, the entire flexible joint 1 together with the mold is placed in a hot air oven for heating and curing. The heating condition is set to 80℃ for 2h. After the heating and curing is completed, the silicone tube is stripped section by section using wire strippers to obtain the prepared flexible joint 1. At the same time, it is necessary to check the eccentricity of the multimode optical fiber 2 in the photothermal conversion elastomer 3 to ensure that the flexible joint 1 has good actuation characteristics.

[0043] See also Figures 2 to 5The optical path system of the light-driven sensing integrated flexible joint includes a flexible joint 1, a 1*3 optical splitter 12, a high-power laser 8 and a sensor component 13, wherein the sensor component includes a tunable laser 9, an optical power meter 10 and an optical isolator 11.

[0044] like Figure 3 As shown, the flexible joint 1 is connected to the port D of the 1*3 optical splitter 12; the high power laser 8 is connected to the port A of the 1*3 optical splitter 12; the tunable laser 9 is connected to the input end of the optical isolator 11, and the output end of the optical isolator 11 is connected to the port B of the 1*3 optical splitter 12; the optical power meter 10 is connected to the port C of the 1*3 optical splitter 12. The driving mode of the optically driven sensing integrated flexible joint is photothermal driving. The high-power laser 8 is connected to the flexible joint 1 through a 1*3 optical splitter 12. When the driving light enters the flexible joint 1, due to the initial bending amount of the flexible joint 1, the transmission characteristics of the optical path will change, and part of the constrained light will become a leakage mode and leak out from the multimode optical fiber 2. Additional energy loss will occur along the bending radius direction, and this part of the leaked light energy will be absorbed by the photothermal conversion elastomer 3 to generate heat. The heat generation of the photothermal conversion elastomer 3 can be controlled by adjusting the output power of the high-power laser 8, so as to control the temperature of the photothermal conversion elastomer 3 and generate a thermal deformation response. The large difference in thermal expansion coefficient between the photothermal conversion elastomer 3 and the multimode optical fiber 2 causes them to generate an interaction force when experiencing temperature changes. This force generates a bending moment on the eccentric structure and completes the driving of the flexible joint movement. The sensing method of the flexible joint 1 adopts fiber Bragg grating sensing: the optical power meter 10 is connected to the multimode optical fiber 2 through a 1*3 optical splitter 12, and the light waves within a specific wavelength range will be modulated by the fiber Bragg grating 7 to form a central wavelength. The central wavelength drifts under the combined action of temperature and strain. The central wavelength drift detected by the optical power meter 10 can reflect the bending condition of the flexible joint 1.

[0045] A high-power laser 8 is selected as a driving light source, with an output power of 0 to 9 W, a wavelength range of 915 to 980 nm, a pigtail of 110 / 125 μm multimode optical fiber, and a numerical aperture of <0.15.

[0046] A tunable laser 9 is selected as the sensing light source, with a wavelength tuning range of 1500-1630 nm, a peak output power ≥13 dBm, and a single-mode optical fiber as the pigtail.

[0047] The optical power meter 10 is selected to analyze the reflection spectrum data of the fiber Bragg grating 7, with a power range of -75 to 1.5 dBm, a wavelength range of 800 to 1600 nm, and a sampling rate of 50 ms.

[0048] The optical isolator 11 is used to protect the tunable laser 9, with an operating wavelength of 1550±20nm and a minimum isolation of 44dB.

[0049] In this embodiment, an IPG PLD-9-962 laser is selected as the high-power laser 8, a SanteC TSL-550 laser is selected as the tunable laser 9, an FPM-8200 fiber power meter is selected as the optical power meter 10, an optical isolator 11 with a working wavelength of 1550±20nm is selected to protect the tunable laser 9, and a 1*3 optical splitter 12 is selected to realize the connection of the optical path system.

[0050] The splitting ratio of the 1*3 optical splitter 12 is equal, and a 105 / 125 μm multimode optical fiber (core diameter is 105 μm, cladding diameter is 125 μm) can be selected.

[0051] The driving light output by the high-power laser 8 passes through the 1*3 optical splitter 12 to the flexible joint 1, and the driving light power of the high-power laser 8 is controlled to change the amplitude and speed of the bending movement of the flexible joint 1. The tunable laser 9 outputs the sensing light through the optical isolator 11 and the 1*3 optical splitter 12 to the fiber Bragg grating 7 inside the flexible joint 1, and the reflected spectrum light signal passes through the 1*3 optical splitter 12 to the optical power meter 10, and the bending curvature of the flexible joint 1 is obtained by analysis.

[0052] In the initial state, the flexible joint 1 has a certain amount of bending. In the working state, the high-power laser 8, the tunable laser 9 and the optical power meter 10 are started, and the driving light and the sensing light are coupled to the flexible joint 1 with the help of the 1*3 optical splitter 12. Due to the bending loss of the multimode optical fiber 2, part of the driving light leaks from the multimode optical fiber 2 to the photothermal conversion elastomer 3, causing the temperature to rise. Since the thermal expansion coefficients of the multimode optical fiber 2 and the photothermal conversion elastomer 3 are different, when the temperature changes, unbalanced thermal stress is generated inside the flexible joint 1, causing the flexible joint 1 to bend. At the same time, the change angle of the flexible joint 1 is obtained by analyzing the reflection spectrum signal of the fiber Bragg grating 7 measured by the optical power meter 10.

[0053] It can be seen that the light-driven sensing integrated flexible joint and its optical path system described in the present invention use multi-mode optical fiber as the energy transmission medium, and engrave fiber Bragg gratings on the multi-mode optical fiber, integrating the sensing and driving functions of the flexible joint into one, with low manufacturing cost and strong applicability. It can be used in corrosive, radiation, flammable and explosive environments, and is expected to be used in medical, fuel pipeline, military and other fields.

[0054] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0055] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0056] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A light-driven sensing integrated flexible joint based on photothermal effect, characterized in that: It includes a multimode optical fiber and a photothermal conversion elastomer, wherein the photothermal conversion elastomer is in an arc-shaped joint shape, the photothermal conversion elastomer contains a material for photothermal conversion, and the multimode optical fiber is eccentrically embedded in the photothermal conversion elastomer; A fiber Bragg grating is engraved on the core of the multimode optical fiber, and the midpoint of the fiber Bragg grating is flush with the midpoint of the flexible joint; When the incident light power of the multimode optical fiber increases, the photothermal conversion elastomer will bend in the direction of decreasing curvature, and the reflection spectrum signal of the fiber Bragg grating reflects the changing angle of the photothermal conversion elastomer.

2. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The multimode optical fiber is embedded in a position close to the large radius side of the arc-shaped joint of the photothermal conversion elastic body.

3. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The materials used for photothermal conversion are gold nanoparticles, carbon nanotubes or graphene oxide powder with photothermal effect.

4. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The reflection peak wavelength range of the fiber Bragg grating is 1550-1630nm, the length is 1-15mm, and the reflectivity is at least 90%.

5. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The multimode optical fiber is in an eccentric state inside the photothermal conversion elastomer, and the eccentricity ranges from 0 to 375 μm. The actuation effect of the flexible joint becomes better as the eccentricity increases.

6. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The material of the photothermal conversion elastomer is a material with a large thermal expansion coefficient and a small specific heat capacity.

7. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The material of the photothermal conversion elastomer is epoxy resin or polyimide plastic.

8. The light-driven sensing integrated flexible joint based on photothermal effect according to claim 1 is characterized in that: The thermal expansion coefficients of multimode optical fiber and photothermal conversion elastomer are different. When the temperature changes, the flexible joint bends due to the unbalanced thermal stress generated inside.

9. The light-driven sensing integrated flexible joint based on photothermal effect according to any one of claims 1 to 8, characterized in that: The multimode optical fiber is also provided with a cladding and a coating layer outside the core, wherein the core diameter is 105 μm, the cladding diameter is 125 μm, and the coating diameter is 250 μm.

10. An optical path system for a light-driven sensing integrated flexible joint, characterized in that: It includes a flexible joint, a 1*3 optical splitter, a high-power laser and a sensor component, wherein the sensor component includes a tunable laser, an optical power meter and an optical isolator, the high-power laser is connected to the first branch port of the 1*3 optical splitter; the input end of the optical isolator is connected to the tunable laser, and the output end of the optical isolator is connected to the second branch port of the 1*3 optical splitter; the optical power meter is connected to the third branch port of the 1*3 optical splitter, and the flexible joint is connected to the combining port of the 1*3 optical splitter, wherein the flexible joint is an optically driven sensing integrated flexible joint based on photothermal effect as described in any one of claims 1 to 9.

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