A high-sensitivity temperature sensor based on double-helix micro-nano fiber structure

Abstract

The application discloses a high-sensitivity temperature sensor based on a double-helix micro-nano fiber structure. The double-helix micro-nano fiber is placed on a flexible substrate and embedded by a flexible film, and the double-helix micro-nano fiber is mainly formed by parallel helical winding of a straight-through micro-nano fiber and a coupling micro-nano fiber, wherein one end of the straight-through micro-nano fiber is connected with a white light source, and the other end of the coupling micro-nano fiber is connected with a spectrometer; the double-helix micro-nano fiber comprises the straight-through micro-nano fiber and the coupling micro-nano fiber, both ends of the two fibers are aligned, the waist diameters of the two fibers are consistent, and the waist lengths of the two fibers are the same; the straight-through micro-nano fiber and the coupling micro-nano fiber are both mainly composed of unstretched portions located at both ends, a waist section located at the center and taper transition zones located between the waist section and the unstretched portions at both ends of the waist section. The application can sensitively perceive temperature change, and has the advantages of compact structure, high sensitivity, simple preparation, low cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology and relates to a fiber optic temperature sensor, particularly a highly sensitive micro / nano fiber optic temperature sensor with a strong evanescent field coupling device. Background Technology

[0002] Temperature, as a physical quantity characterizing the degree of hotness or coldness of an object, is one of the important measurement parameters in research fields such as petrochemicals, biomedicine, and robotics tactile sensing. Fiber optic sensors have attracted widespread attention in temperature sensing due to their excellent properties such as resistance to electromagnetic interference, corrosion resistance, and no crosstalk. In recent years, many fiber optic sensors have been applied to temperature monitoring, including fiber Bragg gratings (FBGs), long-period fiber gratings (LPFGs), surface plasmon resonance (SPR), fiber interferometers, tapered fibers, Mach-Zehnder interferometers (MZIs), and other structures. Although they have advantages such as small size and fast response, some key problems still need to be solved. For example, FBG and LPFG-based sensors require expensive high-power lasers in their manufacturing process. In addition, the low thermo-optic and thermal expansion coefficients of silica-based fiber materials result in relatively low sensitivity for most traditional fiber optic temperature sensors.

[0003] Micro- and nano-fibers are a new type of optical waveguide developed in recent years, with diameters close to or smaller than the wavelength of light. Their diameters can be 2-3 orders of magnitude smaller than ordinary optical fibers, and they possess advantages such as small size, strong optical field confinement, large evanescent field ratio, good mechanical properties, small bending radius, and low loss. Due to their large evanescent field, micro- and nano-fibers have shown great application potential in fiber optic sensing. Representative research teams include Professor Bramblla's team at the University of Southampton, UK; Professor Tong Limin's team at Zhejiang University; Professor Rao Yunjiang's team at the University of Electronic Science and Technology of China; Professor Guan Bai'ou's team at Jinan University; and Professor Wang Yiping's team at Shenzhen University. However, current temperature sensors based on micro- and nano-fibers generally have sensitivity in the nm / ℃ range, which cannot achieve accurate temperature signal detection, limiting their application in many situations. Summary of the Invention

[0004] To address the problems existing in the background technology, the purpose of this invention is to provide a method for fabricating a double-helix micro / nano fiber temperature sensor. This method involves spirally winding the waist regions of two parallel micro / nano fibers together and encapsulating them in PDMS, a flexible material with a high thermo-optic coefficient, to form an accurate, low-cost, high-sensitivity, and easily fabricated double-helix micro / nano fiber sensor.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention includes a white light source, a double-helix micro / nano fiber, a spectrometer for spectral detection, a flexible substrate for placing the double-helix micro / nano fiber, and a flexible film for covering the micro / nano fiber. The double-helix micro / nano fiber is placed on the flexible substrate and embedded in the flexible film. The double-helix micro / nano fiber is mainly composed of a through micro / nano fiber and a coupled micro / nano fiber that are spirally wound in parallel with each other. One end of the unstretched portion of the through micro / nano fiber is connected to the white light source, and the other end of the unstretched portion of the coupled micro / nano fiber is connected to the spectrometer.

[0007] A beam of light is emitted from a white light source, coupled to the waist region of the coupled micro-nano fiber via an evanescent wave, and oscillates back and forth between the through-micro-nano fiber and the coupled micro-nano fiber before finally being transmitted to the spectrometer.

[0008] The aforementioned double-helix micro / nano fiber includes a through micro / nano fiber and a coupled micro / nano fiber, both of which are aligned at both ends and have the same waist diameter and waist length. Both the through micro / nano fiber and the coupled micro / nano fiber are mainly composed of unstretched portions at both ends, a waist section in the center, and a tapered transition region between the waist section and the unstretched portion.

[0009] Both the flexible substrate and the flexible film are flexible polydimethylsiloxane (PDMS) materials, which have advantages such as low refractive index, high thermo-optic coefficient, high flexibility and good biocompatibility, making them very suitable as a temperature sensing medium.

[0010] A high thermo-optic coefficient refers to a material whose refractive index changes rapidly with temperature.

[0011] The diameter of the waist region is smaller than the diameter of the unstretched portion, and the diameter of the tapered transition region gradually decreases from the end connecting the unstretched portion to the end connecting the waist region.

[0012] The waist region and the tapered transition regions at both ends are covered by a flexible film on a flexible substrate.

[0013] In the aforementioned double-helix micro / nano fiber, the through micro / nano fiber and the coupled micro / nano fiber are formed by their own waist region being wound in a double helix manner.

[0014] The aforementioned double-helix micro / nano fiber, comprising a through micro / nano fiber and a coupled micro / nano fiber, is obtained through the following process:

[0015] Two standard single-mode optical fibers are fixed parallel to each other on the optical fiber pressing platform using optical fiber pressing pads. The two optical fiber pressing platforms are installed on their respective tapered platforms. The single-mode optical fibers are heated by the hydrogen flame generated by water electrolysis until they reach the molten state. Then the tapered platforms drive the two optical fiber pressing platforms to stretch to both sides at a speed of 0.1 mm / s until the single-sided stretch length of the optical fiber is 2 mm.

[0016] By setting a tapered platform to drive two fiber pressing stages to move in the same direction at speeds of 2.1 mm / s and 1.9 mm / s respectively, the tapered platform continues to drive the two fiber pressing stages to move in the same direction at speeds of 2.1 mm / s and 1.9 mm / s respectively. The hydrogen flame generated by water electrolysis is used to heat and scan the thinner fiber segment in the middle of the single-mode fiber. The effective flame size changes linearly with the fiber stretching length, while the fiber diameter decreases as the stretching length increases. The stretching and heating stops when the diameter is about 0.8 μm-0.9 μm and the length is about 33-35 mm. The segment with a diameter of about 0.8 μm-0.9 μm is designated as the waist region. After cooling, two parallel micro-nano fibers with aligned ends are formed, which serve as the through micro-nano fiber and the coupled micro-nano fiber, respectively.

[0017] One unstretched portion of the through micro / nano fiber and the coupled micro / nano fiber are placed parallel to each other on the fiber clamp. The other unstretched portions of the through micro / nano fiber and the coupled micro / nano fiber are placed parallel to each other on the fiber rotator. After removing the fiber pressure pad on the fiber pressure table, the fiber clamp and the fiber rotator are moved and raised to the same height simultaneously by a one-dimensional adjustment frame. The fiber rotator rotates to make the waist region of the through micro / nano fiber and the coupled micro / nano fiber spirally wound together. The coupling length of the waist region is adjusted by the number of rotations to form a double-helix micro / nano fiber.

[0018] The aforementioned double-helix micro / nano optical fiber is placed on a flexible substrate and then covered with a flexible thin film.

[0019] One end of the unstretched portion of the straight-through micro-nano fiber is connected to a white light source. The white light source emits a beam of light, which passes through the straight-through micro-nano fiber and connects to a spectrometer at the other end of the unstretched portion of the coupled micro-nano fiber.

[0020] Temperature is conducted to a micro / nano fiber optic sensor embedded in a flexible thin film with a high thermo-optic coefficient. The temperature changes the refractive index of the flexible thin film material, which alters the coupling oscillation period of the micro / nano fiber. This, in turn, changes the splitting ratio of the light beam emitted from the white light source through the through-micro / nano fiber and the coupled micro / nano fiber. Temperature can then be obtained by monitoring the change in wavelength shift after interference, thus enabling temperature detection.

[0021] The double-helix micro-nano fiber optic sensor of the present invention can be used as a non-contact temperature sensor. Its sensitive part and the object being measured do not need to be in contact to detect temperature with high sensitivity. It can generally be used to measure the surface temperature of moving objects, small targets or objects with rapidly changing temperature, and to measure the temperature distribution of the temperature field. In addition, this sensor has great application value in the fields of artificial intelligence machine safety obstacle avoidance and microfluidic fluid temperature measurement.

[0022] Compared with existing technologies, the beneficial effects of this invention are:

[0023] (1) Two micro-nano optical fibers are placed on a tapered platform with parallel to each other and aligned at both ends, and have the characteristics of consistent diameter and waist length.

[0024] (2) The fiber tapering machine used in this invention can effectively control the waist diameter and waist length of the two micro-nano fibers, and the fiber rotator used can adjust the coupling length of the middle waist section of the micro-nano fiber spirally wound together, thereby helping to improve the sensitivity of the sensor.

[0025] (3) The wound micro-nano fiber temperature sensing sensor based on the optical principle of evanescent wave coupling has the characteristics of simple structure, easy fabrication, low cost, small size and high sensitivity.

[0026] (4) The double-helix micro-nano fiber is encapsulated in flexible material PDMS, which provides overall protection for the fragile photonic structure. It has excellent flexibility and biocompatibility, improves the robustness of the micro-nano fiber chip, and at the same time protects the micro-nano fiber from external influences such as dust.

[0027] (5) The flexible material PDMS used in this invention has stable chemical properties, low refractive index, high thermo-optic coefficient, high flexibility and good biocompatibility, making it very suitable as a temperature sensing medium and able to significantly improve the sensitivity of the sensor.

[0028] (6) This invention can be used as a non-contact temperature sensor to test the palm at different distances perpendicular to the sensor, to measure the surface temperature of moving objects, small targets or objects with rapidly changing temperatures, and to measure the temperature distribution of the temperature field.

[0029] (7) The temperature sensing sensor of the present invention has great application value in fields such as artificial intelligence machine safety obstacle avoidance and microfluidic fluid temperature measurement. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the double-helix micro / nano fiber optic sensor of the present invention in use;

[0031] Figure 2 This is a schematic diagram of the linear micro / nano fiber tapered structure of the present invention;

[0032] Figure 3 This is a schematic diagram of the fabrication structure of the double-helix micro / nano optical fiber of the present invention;

[0033] Figure 4 This is a graph showing the relationship between temperature and coupling wavelength of the double-helix micro / nano fiber optic sensor of this invention.

[0034] Figure 5 This is a transmittance diagram of the double-helix micro / nano fiber optic sensor of the present invention at different distances.

[0035] In the figure: 1—White light source; 2—Spectrometer; 3—Heating stage; 4—Flexible substrate; 5—Flexible thin film; 6—Through-type micro / nano fiber; 7—Coupled-type micro / nano fiber;

[0036] 8—Unstretched portion of micro / nano fiber; 9—Tap transition zone of micro / nano fiber; 10—Waist region of micro / nano fiber; 11—Fiber pressure platform; 12—Tap platform; 13—Fiber fixing clamp; 14—Flame; 15—Fiber rotator. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.

[0038] like Figure 1 As shown, it includes a white light source 1, a double-helix micro / nano fiber, a spectrometer 2 for spectral detection, a flexible substrate 4 for placing the double-helix micro / nano fiber, and a flexible film 5 for covering the micro / nano fiber. The double-helix micro / nano fiber is placed on the flexible substrate 4 and embedded in the flexible film 5. The double-helix micro / nano fiber is mainly composed of a through micro / nano fiber 6 and a coupling micro / nano fiber 7 that are spirally wound in parallel with each other. One end of the through micro / nano fiber 6 is connected to the white light source 1, and the other end of the coupling micro / nano fiber 7 is connected to the spectrometer 2.

[0039] A beam of light is emitted from white light source 1. The beam passes through a straight micro-nano fiber 6 and the splitting ratio of the straight micro-nano fiber 6 and the coupled micro-nano fiber 7 changes. The temperature can then be detected by monitoring the wavelength shift after interference using a spectrometer 2.

[0040] The double-helix micro / nano fiber includes a through micro / nano fiber 6 and a coupled micro / nano fiber 7, both of which are aligned at both ends and have the same waist diameter and waist length. Both the through micro / nano fiber 6 and the coupled micro / nano fiber 7 are mainly composed of two unstretched portions 8 at both ends, a waist section 10 in the middle, and two tapered transition sections 9 located between the two ends of the waist section 10 and the unstretched portions 8, respectively. The two ends of the tapered transition sections 9 are respectively connected to one end of their respective unstretched portions 8 and one end of their respective waist sections 10.

[0041] Both ends of the double-helix micro / nano fiber are unstretched portions 8, maintaining the original state and dimensions of the micro / nano fiber. A waist region 10 is located between the two unstretched portions 8, situated in the middle of the micro / nano fiber. The waist region 10 has a uniform diameter throughout, smaller than that of the unstretched portions 8. Each end of the waist region 10 is connected to one end of the unstretched portion 8 via a tapered transition region 9. The other end of the unstretched portion 8 of the straight-through micro / nano fiber 6 is connected to a white light source 1. The unstretched portion 8 of the coupled micro / nano fiber 7 is connected to a spectrometer 2. The white light source 1 and the spectrometer 2 are located at opposite ends of the double-helix micro / nano fiber.

[0042] The tapered transition zone 9 transitions between the waist zone 10 and the unstretched portion 8 by connecting the different diameters at their ends. Specifically, the diameter of the end of the tapered transition zone 9 connected to the waist zone 10 is the same as the diameter of the waist zone 10, and the diameter of the end of the tapered transition zone 9 connected to the unstretched portion 8 is the same as the diameter of the unstretched portion 8.

[0043] The tapered transition zone 9 transitions between the waist zone 10 and the unstretched portion 8, connecting their different diameters. The diameter of the waist zone 10 is smaller than that of the unstretched portion 8, and the diameter of the tapered transition zone 9 gradually decreases from the end connecting the unstretched portion 8 to the end connecting the waist zone 10.

[0044] The waist region 10 and the tapered transition regions 9 at both ends are covered by a flexible film 5 on the flexible substrate 4. The diameter of the waist region 10 is about 0.8-0.9 μm, and the length of the waist region 10 is about 33-35 mm.

[0045] The diameter of the unstretched portion 8 is fixed and remains constant, with a size of 8.2 / 125μm.

[0046] In the double-helix micro / nano fiber, the through micro / nano fiber 6 and the coupled micro / nano fiber 7 are formed by their own waist region 10 wound in a double helix manner. The through micro / nano fiber 6 is arranged in a helical arrangement as one helix, and the coupled micro / nano fiber 7 is arranged in a helical arrangement as another helix.

[0047] The double-helix micro / nano fiber, comprising a through micro / nano fiber 6 and a coupled micro / nano fiber 7, is obtained by processing in the following manner:

[0048] like Figure 2 As shown, two standard single-mode optical fibers are fixed parallel to each other on fiber pressing platforms 11 using pressure pads. The two fiber pressing platforms 11 are respectively mounted on their respective tapered platforms 12. Hydrogen gas 14 generated by water electrolysis is used to heat the single-mode optical fibers until they reach a molten state. Then, the tapered platforms 12 drive the two fiber pressing platforms 11 to simultaneously stretch the fibers to both sides at a speed of 0.1 mm / s until the single-sided stretch length of the fiber is 2 mm. Next, one tapered platform continues scanning at a speed of 2.1 mm / s, while the other tapered platform moves in the same direction at a speed difference of 0.2 mm / s. The effective flame size changes linearly with the fiber stretch length, while the fiber diameter decreases as the stretch length increases, until the diameter reaches approximately 0.8 μm-0.9 μm and the length is approximately 33-35 mm, at which point stretching and heating cease. The section with a diameter of approximately 0.8 μm-0.9 μm is designated as the waist region 10. After cooling, it forms two parallel micro / nano fibers with aligned ends, serving as the through micro / nano fiber 6 and the coupled micro / nano fiber 7, respectively.

[0049] The two standard single-mode optical fibers are Corning, 8.2 / 125μm.

[0050] like Figure 3 As shown, the unstretched portions 8 of the through micro-nano fiber 6 and the coupled micro-nano fiber 7 are placed parallel to each other on the fiber fixing clamp 13, and the unstretched portions 8 of the other ends of the through micro-nano fiber 6 and the coupled micro-nano fiber 7 are placed parallel to each other on the fiber rotator 15. After removing the rivets on the fiber pressure table 11, the fiber fixing clamp 13 and the fiber rotator 15 are moved and raised to the same height by a one-dimensional adjustment frame. The fiber rotator 15 rotates to make the waist region 10 of the through micro-nano fiber 6 and the coupled micro-nano fiber 7 spirally wound together. The coupling length of the waist region 10 is adjusted by the number of rotations to form a double helical micro-nano fiber.

[0051] Double-helix micro / nano optical fibers are placed on a flexible substrate 4 with a high thermo-optic coefficient, and then covered with a flexible thin film 5 with a high thermo-optic coefficient.

[0052] The double-helix micro / nano optical fiber is attached to the flexible substrate 4 in a straight line.

[0053] The refractive indices of the flexible substrate 4 and the flexible thin film 5 should be greater than the refractive index of air, less than the refractive index of the micro-nano optical fiber, and less than the refractive index of SiO2, to ensure that the light is well confined in the micro-nano optical fiber and to ensure the light guiding characteristics of the micro-nano optical fiber.

[0054] The flexible substrate 4 and flexible film 5 materials have large thermo-optic coefficients, ensuring that the designed sensor is sensitive to temperature.

[0055] The temperature detected by this invention is calibrated by the change in the displacement of the coupled wavelength.

[0056] Micro- and nano-fibers are embedded in the flexible material polydimethylsiloxane (PDMS). The flexible material PDMS has stable chemical properties over a wide operating temperature range of -60 to 200°C. It also has advantages such as low refractive index, high thermo-optic coefficient, high flexibility, and good biocompatibility, making it very suitable as a temperature sensing medium and significantly improving the sensitivity of the sensor.

[0057] Temperature is conducted to a double-helix micro / nano fiber optic sensor embedded in a flexible thin film material. The temperature changes the refractive index of the flexible thin film material, which alters the coupling vibration period of the micro / nano fiber. This, in turn, changes the splitting ratio of the light beam emitted from the white light source through the through-micro / nano fiber and the coupled micro / nano fiber. Temperature can then be obtained by monitoring the change in wavelength shift after interference, thus enabling temperature detection.

[0058] When the ambient temperature of the micro / nano fiber chip increases, the refractive index of the flexible polymer material decreases, and the normalized cutoff frequency of the micro / nano fiber chip increases, which will cause a blue shift in the coupling wavelength of the micro / nano fiber, thereby realizing temperature sensing.

[0059] Micro- and nano-fibers are embedded in flexible polydimethylsiloxane (PDMS). Due to the advantages of PDMS film material, such as low Young's modulus, strong corrosion resistance, high dielectric strength, and strong optical transparency, it can be used as a substrate material for large-area transparent flexible electronic devices or thermally stable devices. Therefore, the micro- and nano-fiber chips embedded in flexible materials of this invention have good robustness and stability.

[0060] The flexible material PDMS used in this invention has stable chemical properties, low refractive index, high thermo-optic coefficient, high flexibility and good biocompatibility in a wide operating temperature range of -60 to 200°C, making it very suitable as a temperature sensing medium and able to significantly improve the sensitivity of the sensor.

[0061] In a specific implementation, an electric heating stage 3 is used to heat the double-helix micro-nano fiber optic sensor for temperature detection experiments, and a flexible substrate 4 is placed on the electric heating stage 3.

[0062] The embodiments of the present invention are as follows:

[0063] The following examples, using flexible material polydimethylsiloxane (PDMS) and single-mode optical fiber (Corning, 8.2 / 125μm), illustrate the fabrication and technical effects of the temperature sensor based on double-helix micro / nano optical fiber of the present invention.

[0064] 1. Preparation process

[0065] In this embodiment, the flexible substrate and flexible film are made of PDMS with a refractive index of 1.397, which can better confine the light to the micro-nano fiber optic sensor and obtain high sensing sensitivity.

[0066] 0.5 mL of uncured PDMS was placed on a glass substrate and heated on an 80°C electric heating stage for 20 minutes to form a PDMS flexible substrate with a thickness of 250 μm. A double-helix micro / nano fiber with a diameter of about 0.8 μm-0.9 μm and a waist length of 33-35 mm was placed on the PDMS flexible substrate. 0.3 mL of uncured PDMS was poured onto the double-helix micro / nano fiber on the flexible substrate and heated on an 80°C electric heating stage for 20 minutes to form a double-helix micro / nano fiber sensor.

[0067] 2. Temperature test

[0068] In this embodiment, without applying additional pressure to the micro / nano fiber optic sensor, the heating stage 3 is turned on. The heating stage 3 only changes the temperature of the micro / nano fiber optic sensor. When the ambient temperature of the micro / nano fiber optic chip increases, the refractive index of the flexible polymer material decreases, and the normalized cutoff frequency of the micro / nano fiber optic chip increases, causing a blue shift in the coupling wavelength of the micro / nano fiber, thus achieving temperature sensing. Throughout the test, a white light source is connected to one end of the through-hole micro / nano fiber optic sensor, and a spectrometer is connected to the other end of the coupled micro / nano fiber. The spectrum changes with temperature as shown in the figure. Figure 4 As shown.

[0069] Figure 4 This indicates that when the temperature rises from 39.0℃ to 40.0℃, the coupling wavelength blue-shifts from 832nm to 803nm. The sensitivity of the double-helix micro / nano fiber optic sensor is as high as 29nm / ℃. The relationship between the coupling wavelength and temperature can be expressed by a linear equation: λ=-33.345T+2146.8, with a linear correlation coefficient of 0.997. 3. Distance Measurement

[0070] In this embodiment, the double-helix micro / nano fiber optic sensor can be used as a non-contact temperature sensor. Its sensitive part does not need to contact the object being measured to detect temperature with high sensitivity. When the test hand is placed at different distances perpendicular to the sensor, it will exhibit different signal intensities. The variation of its spectral intensity with distance is shown in the figure below. Figure 5 As shown;

[0071] Figure 5 This indicates that the farther the palm is from the sensor, the smaller the change in spectral intensity; conversely, the closer the palm is to the sensor, the greater the change in spectral intensity. The inset is a linear curve of distance versus intensity.

[0072] In this embodiment, the double-helix micro-nano fiber optic temperature sensor can generally be used to measure the surface temperature of moving objects, small targets, or objects with rapidly changing temperatures, and to measure the temperature distribution of the temperature field. Therefore, this sensor can be applied in fields such as obstacle avoidance for artificial intelligence machines.

Claims

1. A highly sensitive temperature sensor based on a double-helix micro / nano fiber structure, characterized in that: The system includes a white light source (1), a double-helix micro / nano fiber, a spectrometer (2) for spectral detection, a flexible substrate (4) for placing the double-helix micro / nano fiber, and a flexible film (5) for covering the micro / nano fiber. The double-helix micro / nano fiber is placed on the flexible substrate (4) and embedded in the flexible film (5). The double-helix micro / nano fiber is mainly composed of a through micro / nano fiber (6) and a coupling micro / nano fiber (7) that are spirally wound in parallel with each other. One end of the unstretched portion of the through micro / nano fiber (6) is connected to the white light source (1), and the other end of the unstretched portion of the coupling micro / nano fiber (7) is connected to the spectrometer (2). A beam of light is emitted from the white light source (1), and is coupled to the waist region of the coupling micro-nano fiber (7) through the evanescent wave of the coupling waist region of the through micro-nano fiber (6), and oscillates back and forth between the through micro-nano fiber (6) and the coupling micro-nano fiber (7), and is finally transmitted to the spectrometer (2). The waist diameter of the straight-through micro / nano fiber (6) and the coupled micro / nano fiber (7) is 0.8 μm-0.9 μm; In the aforementioned double-helix micro-nano fiber, the through micro-nano fiber (6) and the coupled micro-nano fiber (7) are formed by their own waist region (10) wrapped in a double helix manner; The aforementioned double-helix micro / nano fiber, comprising a through micro / nano fiber (6) and a coupled micro / nano fiber (7), is obtained by processing in the following manner: Two single-mode optical fibers are fixed in parallel on the optical fiber pressing platform (11) using optical fiber pressing pads. The two optical fiber pressing platforms (11) are installed on their respective tapered platforms (12). The single-mode optical fibers are heated by the hydrogen flame (14) generated by water electrolysis until they reach the molten state. Then the tapered platform (12) drives the two optical fiber pressing platforms (11) to stretch to both sides at the same time until the single-sided stretching length of the optical fiber is 2 mm. By setting the tapered platform (12) to drive the two fiber pressing platforms (11) to move in the same direction at the same speed until the stretching and heating stop at a diameter of about 0.8 μm-0.9 μm and a length of about 33-35 mm, the section with a diameter of about 0.8 μm-0.9 μm is taken as the waist region (10). After cooling, two parallel micro-nano fibers with their ends aligned are formed, which are respectively used as the through micro-nano fiber (6) and the coupled micro-nano fiber (7). One end of the straight micro-nano fiber (6) and the unstretched portion (8) of the coupled micro-nano fiber (7) are placed parallel to each other on the fiber fixing clamp (13). The other end of the straight micro-nano fiber (6) and the unstretched portion (8) of the coupled micro-nano fiber (7) are placed parallel to each other on the fiber rotator (15). After removing the fiber pressure pad on the fiber pressure table (11), the fiber fixing clamp (13) and the fiber rotator (15) are moved and raised to the same height simultaneously by a one-dimensional adjustment frame. The fiber rotator (15) rotates to make the waist region (10) of the straight micro-nano fiber (6) and the coupled micro-nano fiber (7) spirally wound together. The coupling length of the waist region (10) is adjusted by the number of rotations to form a double helix micro-nano fiber. The double-helix micro-nano optical fiber is placed on a flexible substrate (4) and then covered with a flexible film (5).

2. The high-sensitivity temperature sensor based on a double-helix micro / nano fiber structure according to claim 1, characterized in that: The double-helix micro-nano fiber includes a straight micro-nano fiber (6) and a coupled micro-nano fiber (7), with both ends aligned and having the same waist diameter and waist length. Both the straight micro-nano fiber (6) and the coupled micro-nano fiber (7) are mainly composed of unstretched portions (8) at both ends, a waist section (10) in the center, and a tapered transition region (9) between the waist section (10) and the unstretched portion (8).

3. A high-sensitivity temperature sensor based on a double-helix micro / nano fiber structure according to claim 2, characterized in that: The diameter of the waist region (10) is smaller than the diameter of the unstretched portion (8), and the diameter of the tapered transition region (9) gradually decreases from the end connecting the unstretched portion (8) to the end connecting the waist region (10).

4. A high-sensitivity temperature sensor based on a double-helix micro / nano fiber structure according to claim 2, characterized in that: The waist region (10) and the tapered transition regions (9) at both ends are covered by a flexible film (5) on a flexible substrate (4).

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