Micro-nano optical fiber olfaction sensor based on evanescent wave absorption

Abstract

The invention discloses a micro-nano optical fiber olfaction sensor based on evanescent wave absorption. The micro-nano optical fiber olfaction sensor comprises a light source, a micro-nano optical fiber, a flexible film, a gas molecule indicator and a detector, the micro-nano optical fiber comprises two sections of unstretched parts, two sections of conical transition areas and a waist area, and the unstretched parts at the two ends of the micro-nano optical fiber are connected with the light source and the detector respectively; the two sections of conical transition regions and the waist region of the micro-nano optical fiber are packaged by independent flexible films; the flexible film is doped with a gas molecule indicator, and the gas molecule indicator is sensitive to the PH of the flexible film and can change color according to the PH of the flexible film; the olfactory sensing device can realize olfactory sensing with high sensitivity, large detection range and quick response, has the advantages of compact structure, high expansibility, electromagnetic interference resistance and the like, can be widely applied to detection of various types of gases, and has great application value in the fields of intelligent robots, industrial production, disease diagnosis, environmental monitoring and the like.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, specifically a micro / nano fiber optic olfactory sensor based on evanescent wave absorption. Background Technology

[0002] Smell is a vital sensory activity for organisms to obtain information from the external environment. For example, in humans, olfactory cells inside the nose bind with different types of gas molecules, generating electrical signals that are transmitted to the olfactory center in the brain, enabling the detection and differentiation of different odors and chemical substances—this is the olfactory function. Smell plays a crucial role in the survival of organisms, helping them determine the freshness of food, detect potential dangers, and identify suitable mates. Furthermore, olfaction has wide applications in industry, medicine, and the environment. For instance, gas sensors can detect and analyze gas components, playing a vital role in industrial production, disease diagnosis, and environmental monitoring.

[0003] Current olfactory sensors are mostly based on electrical principles, commonly including electrochemical gas sensors and semiconductor gas sensors. Their advantages include low cost, good stability, and wide detection range. However, these sensors are susceptible to electromagnetic interference and cannot operate in strong electromagnetic or flammable / explosive environments, limiting their application scenarios. Olfactory sensors based on optical principles typically feature small size and high sensitivity. In particular, optical fibers, made of insulating dielectric materials, offer advantages such as resistance to electromagnetic interference, chemical corrosion, and high temperature and pressure, giving them significant advantages in many applications.

[0004] In recent years, with the development of fiber optic sensing technology, optical-based gas measurement methods have emerged. For example, docking-coupled fiber optic gas sensors directly couple a gas absorption cell to an optical fiber, offering advantages such as simple fabrication and good stability, but suffer from larger size and lower sensitivity. Another example is the fiber end-face hydrogen sensor fabricated using two-photon polymerization, where the palladium film absorbs hydrogen, causing volume expansion and altering the cavity length of the Fabry-Perot cavity on the fiber end-face. This sensor is smaller in size, but its detection system is complex and its response speed is slow. Yet another example is the gas sensor based on a single polymer nanowire, where gas molecules alter the optical properties of the polymer fiber itself. This sensor boasts a simple structure, high sensitivity, and fast response speed, but it exhibits lower flexibility and incompatibility with standard optical fibers, making effective integration and practical application difficult.

[0005] Micro- and nano-fibers are a novel type of optical waveguide. Their waist diameter is close to or smaller than the wavelength of the transmitted light, allowing a significant portion of the energy to propagate as evanescent waves in the external medium. These evanescent waves are highly sensitive to changes in the external environment and can interact with gas molecules diffused in the external medium to generate evanescent absorption, thus enabling gas sensing. Furthermore, micro- and nano-fibers possess advantages such as small size / mass, low transmission loss, a large evanescent field ratio, high mechanical strength, and perfect compatibility with standard optical fibers. Sensors based on micro- and nano-fibers typically exhibit small size, high sensitivity, fast response, and low power consumption, making it possible to fabricate high-performance, miniaturized olfactory sensors based on evanescent wave absorption.

[0006] Existing micro / nano fiber optic olfactory sensors have the following technical problems:

[0007] 1) When using a glass substrate to fix micro / nano optical fibers and encapsulate gas-sensitive films, the tapered diameter of the fiber can easily lead to significant unevenness in film thickness during the coating process. In the narrower diameter section, surface tension can cause the film to form an ultrathin layer or even break; in the thicker diameter section, the coating solution can stagnate, resulting in excessively thick build-up. This thickness difference leads to inconsistent mode coupling strength in different regions during light transmission within the fiber, causing unpredictable optical scattering losses. These losses exhibit nonlinear interference with changes in gas concentration, making baseline drift of the sensing signal difficult to calibrate and directly reducing measurement accuracy.

[0008] 2) The reliance on bulk substrates for fixation limits device miniaturization. Although micro- and nano-fibers can reach sub-micrometer diameters, the rigid structure of bulk substrates keeps their overall size above the millimeter level, making them unsuitable for mesoscale detection scenarios. In the confined spaces within precision instruments or in micro-reaction systems, sensors are difficult to deploy flexibly, severely limiting their application potential in in-situ monitoring of trace gases.

[0009] In conclusion, it is of practical significance to leverage the advantages of micro- and nano-fibers and develop a miniaturized, compact, highly sensitive, and fast-response micro- and nano-fiber olfactory sensor through novel structural design and gas-sensitive thin-film encapsulation methods. Summary of the Invention

[0010] In view of the above, the purpose of this invention is to provide a micro / nano fiber optic olfactory sensor based on evanescent wave absorption, addressing the shortcomings of the prior art.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention discloses a micro / nano fiber optic olfactory sensor based on evanescent wave absorption, comprising a light source, an unstretched portion of a micro / nano fiber, a tapered transition region of a micro / nano fiber, a waist region of a micro / nano fiber, another tapered transition region of a micro / nano fiber, an unstretched portion of a micro / nano fiber, and a detector, arranged in sequence. The unstretched portion, tapered transition region, waist region, tapered transition region, and unstretched portion of the micro / nano fiber are integrated into one unit. The tapered transition regions of two micro / nano fibers are bonded together. The light source and detector are connected to both ends of the micro / nano fiber, respectively. Both tapered transition regions and the waist region of the micro / nano fiber are encapsulated by a flexible thin film. The flexible thin film is doped with a gas molecule indicator. The evanescent wave transmitted on the surface of the micro / nano fiber is sensitive to the optical absorption characteristics of the flexible thin film, generating evanescent wave absorption related to gas concentration, thereby achieving gas concentration detection. The flexible thin film has the ability to permeate and release gas molecules.

[0013] As a further improvement, the gas molecule indicator described in this invention is uniformly dispersed in a flexible film to form a gas-sensitive film. Different gas-sensitive films can be used to achieve different types of gas sensing, depending on the requirements.

[0014] As a further improvement, the refractive index of the flexible thin film described in this invention is lower than that of the micro / nano optical fiber.

[0015] As a further improvement, the thickness of the flexible film described in this invention is less than or equal to 100 μm.

[0016] As a further improvement, the diameter of the waist region of the micro / nano optical fiber described in this invention is less than 10 μm, and the maximum diameter of the ring formed by bending the waist region is less than 1 mm.

[0017] As a further improvement, the detection principle of the micro / nano fiber optic olfactory sensor based on evanescent wave absorption described in this invention is as follows: gas molecules diffuse into a flexible thin film, thereby changing the pH of the flexible thin film; the gas molecule indicator changes color according to the pH of the flexible thin film, thereby changing the optical absorption characteristics of the flexible thin film; evanescent waves on the surface of the two conical transition regions and the waist region of the micro / nano fiber are transmitted in the flexible thin film; when the optical absorption characteristics of the flexible thin film change due to the gas concentration, the evanescent waves transmitted on the surface of the micro / nano fiber will generate evanescent wave absorption related to the gas concentration; the gas concentration can be obtained by detecting the change in the light signal input to the detector after the light output from the detection light source is transmitted through the micro / nano fiber, thereby realizing the detection of gas, i.e., olfaction.

[0018] Compared with existing technologies, this invention constructs a high-performance micro-nano optical olfactory sensing system through multi-dimensional technological innovation. Its core breakthrough lies in the synergistic optimization of structural design, material application, and functional integration. The beneficial effects of this invention are:

[0019] (1) In terms of structure, this invention adopts a cantilever beam design with two sections of micro-nano fiber tapered transition zones fitting together, completely overturning the spatial limitations of traditional separate structures. This substrate-free suspended configuration utilizes the excellent mechanical properties of micro-nano fibers to achieve a stable working state without external support, greatly reducing the size compared to traditional blocky substrate structures, and successfully breaking through the spatial limitations of mesoscale detection. The waist region, as the core sensing area, ensures the uniformity of the light field distribution by precisely controlling the diameter deviation, laying the foundation for subsequent thin film coating and signal detection. This compact design gives the sensor extremely high flexibility, meeting the needs of applications in confined spaces such as the olfactory module of intelligent robots. The evanescent waves transmitted on the surface of the micro-nano fiber in this invention are sensitive to the optical absorption characteristics of the flexible film, generating evanescent wave absorption related to gas concentration, thereby realizing the detection of gas concentration.

[0020] (2) Innovation in material encapsulation technology brings dual performance improvements. Independent flexible thin film encapsulation forms a physical barrier, effectively isolating airflow disturbances and dust contamination, which is beneficial to improving the stability of the sensor. Compared with micro- and nano-fibers directly exposed to the air, after being encapsulated with flexible thin film, the refractive index of the medium around the micro- and nano-fibers increases, and the proportion of evanescent field distributed around the micro- and nano-fibers further increases, which is beneficial to improving the sensitivity of the sensor.

[0021] (3) The present invention can maintain stability without external support by using micro-nano fiber cantilever beam structure design and thin film encapsulation method. The entire sensing structure can be in complete contact with the external gas environment. At the same time, the flexible film is thin and has a large specific surface area, which helps to improve the sensitivity and response speed of the sensor.

[0022] (4) Based on optical principles, this invention is immune to interference from electromagnetic interference, leakage current, high voltage and other factors, and has more advantages in extreme and special environments, such as strong electromagnetic and flammable and explosive environments. At the same time, the untapered part of the micro-nano fiber is a standard fiber, which can be seamlessly connected with the external light source and detector, making it convenient for real-time detection and long-distance sensing in dangerous environments.

[0023] (5) The micro-nano optical olfactory sensor based on evanescent wave absorption proposed in this invention has a compact structure, high sensitivity, fast response speed, strong scalability and anti-electromagnetic interference. These advantages make it have great application value in industrial leak monitoring, respiratory diagnosis of diseases and ambient air quality detection, and promote the leap of gas sensing technology towards high precision, miniaturization and intelligence. It has great application value.

[0024] (6) The present invention has strong customizability and scalability. Different gas-sensitive thin-film encapsulated micro-nano optical fibers can be used to realize different types of gas sensing according to application requirements. In addition, through the array design of the sensor, it can be used for real-time monitoring and analysis of complex component gases, further improving the performance of the sensor. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a micro / nano fiber optic olfactory sensor based on evanescent wave absorption in use according to the present invention;

[0026] In the figure: 1-light source, 2-unstretched portion of micro / nano fiber, 3-tapered transition region of micro / nano fiber, 4-waist region of micro / nano fiber, 5-flexible film, 6-gas molecule indicator, 7-detector;

[0027] Figure 2 The change in the spectral absorption peak of the ammonia-sensitive Nafion-BTB film in response to ammonia gas;

[0028] Figure 3 This is a graph showing the relationship between the optical transmittance of a micro / nano fiber optic olfactory sensor based on Nafion-BTB thin film and the ambient ammonia concentration.

[0029] Figure 4 The response time and recovery time of ammonia for a micro / nano fiber optic olfactory sensor based on Nafion-BTB thin film;

[0030] Figure 5 The change in the spectral absorption peak of the humidity-sensitive Nafion-CV thin film in response to humidity;

[0031] Figure 6 This is a graph showing the relationship between the optical transmittance of a micro / nano fiber optic olfactory sensor based on Nafion-CV thin film and the ambient relative humidity.

[0032] Figure 7 This refers to the response time and recovery time of a micro / nano fiber optic olfactory sensor based on Nafion-CV thin films for humidity. Detailed Implementation

[0033] To more clearly illustrate the technical solution and advantages of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the examples described herein are only a part of the embodiments of the present invention, and not all of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] like Figure 1As shown, this invention discloses a micro / nano fiber optic olfactory sensor based on evanescent wave absorption, comprising, in sequence, a light source 1, an unstretched portion 2 of a micro / nano fiber, a tapered transition region 3 of a micro / nano fiber, a waist region 4 of a micro / nano fiber, another tapered transition region 3 of a micro / nano fiber, the unstretched portion 2 of a micro / nano fiber, and a detector 7; the unstretched portion 2, the tapered transition region 3, the waist region 4, the tapered transition region 3, and the unstretched portion 2 of the micro / nano fiber are integrated, with two tapered transition regions 3 of the micro / nano fiber attached to each other. The light source 1 and detector 7 are connected to both ends of the micro-nano fiber, respectively. The tapered transition region 3 and the waist region 4 of both micro-nano fiber segments are encapsulated by a flexible thin film 5. The flexible thin film is doped with a gas molecule indicator 6, which is sensitive to the pH of the flexible thin film 5 and changes color according to the pH, thus exhibiting different optical absorption characteristics. The evanescent waves transmitted on the surface of the micro-nano fiber are sensitive to the optical absorption characteristics of the flexible thin film 5, generating evanescent wave absorption related to gas concentration, thereby enabling gas concentration detection. The tapered transition region and the waist region of the two micro-nano fiber segments constitute a cantilever beam structure.

[0035] The flexible film 5 has the ability to permeate and release gas molecules; the gas molecule indicator 6 is uniformly dispersed in the flexible film 5 to form a gas-sensitive film. Different gas-sensitive films can be used to achieve different types of gas sensing according to application requirements.

[0036] The thickness of the flexible film 5 is less than or equal to 100 μm; the refractive index of the flexible film 5 is less than that of the micro-nano optical fiber, ensuring that the light is well confined in the micro-nano optical fiber.

[0037] The waist region 4 of the micro / nano fiber has a diameter of less than 10 μm, and the maximum diameter of the ring formed by bending the waist region 4 is less than 1 mm.

[0038] The detection principle of the micro / nano fiber optic olfactory sensor based on evanescent wave absorption is as follows: gas molecules diffuse into the flexible film 5, thereby changing the pH of the flexible film; the acid-base indicator 6 changes color according to the pH of the flexible film 5, thereby changing the optical absorption characteristics of the flexible film 5; the evanescent waves on the surfaces of the two conical transition regions 3 and waist regions 4 of the micro / nano fiber are transmitted in the flexible film 5. When the optical absorption characteristics of the flexible film 5 change due to the gas concentration, the evanescent waves transmitted on the surface of the micro / nano fiber will generate evanescent wave absorption related to the gas concentration; the gas concentration can be obtained by detecting the change in the light signal output by the detection light source 1 after being transmitted through the micro / nano fiber and input to the detector 6, thereby realizing the detection of gas, i.e., olfaction.

[0039] The following describes in further detail a micro-nano fiber optic olfactory sensor based on evanescent wave absorption according to the present invention through several specific embodiments.

[0040] Example 1

[0041] A bromothymol blue-doped Nafion film was selected as the ammonia-sensitive flexible film 5; the selected micro / nano fiber was a multimode fiber (Corning, 62.5 / 125μm), obtained by mechanical stretching under flame heating, and the diameter of the waist region 4 of the micro / nano fiber was [missing information]. about.

[0042] 1. Preparation process

[0043] A Nafion-BTB solution was prepared by mixing 0.01 M bromothymol blue (BTB) with 1 mL Nafion 117 solution. The waist region 4 of the micro / nano fiber was bent into a ring, and the first conical transition region 3-1 and the second conical transition region 3-2 were brought together to obtain a closed-loop micro / nano fiber cantilever beam frame. The closed-loop micro / nano fiber cantilever beam frame was completely immersed in the Nafion-BTB solution and kept there for a period of time. The micro / nano fiber cantilever beam frame was removed from the Nafion-BTB solution. Due to the surface tension of the liquid, a Nafion-BTB film 5 was naturally formed on the micro / nano fiber cantilever beam frame to encapsulate it. The sensor was left to stand for a period of time to allow the Nafion-BTB film 5 to solidify, thus obtaining a micro / nano fiber olfactory sensor based on the Nafion-BTB film.

[0044] 2. Working principle

[0045] BTB is a pH indicator. When ammonia molecules diffuse into the Nafion-BTB film, BTB reacts with the ammonia molecules, changing from an acidic to a basic form, causing the Nafion-BTB film to change from yellow to blue. Figure 2 As shown, its spectral absorption peak will shift from 420 nm to 630 nm, causing the micro-nano fiber to undergo evanescent wave absorption related to the concentration of ammonia molecules. This manifests as the evanescent wave absorption of the micro-nano fiber near the wavelength of 630 nm becoming more and more intense as the concentration of ammonia molecules increases. This causes a change in the signal transmitted from the light source 1 to the detector 6 via the micro-nano fiber, based on which the concentration of ammonia in the environment can be obtained.

[0046] 3. Olfactory test

[0047] In this embodiment, a micro / nano fiber optic olfactory sensor based on a Nafion-BTB thin film was placed under different ammonia concentrations, and the optical transmittance of the micro / nano fiber at a wavelength of 630 nm was monitored. Figure 3 As shown, the Nafion-BTB membrane can effectively respond to ammonia gas concentrations ranging from 0 to 500 ppm. The sensor's response sensitivity to ammonia gas is defined as S. c= ΔT / ΔC, where ΔT is the change in the optical transmittance of the sensor and ΔC is the change in the ambient ammonia concentration. The sensor's sensitivity to ammonia reaches 2.82% / ppm (0-10 ppm), and the system noise is about 0.1%. Therefore, the sensor's detection limit for ammonia can reach 28 ppb, which shows that the sensor has a very high sensitivity to ammonia.

[0048] like Figure 4 As shown, the ammonia response and recovery time of the micro-nano fiber optic olfactory sensor based on Nafion-BTB film were tested using rapidly changing ammonia concentration. The results showed that the response time was 80 ms and the recovery time was 1.5 s, indicating that the sensor has a very fast response speed to ammonia.

[0049] Example 2

[0050] A crystal violet-doped Nafion film was selected as the humidity-sensitive flexible film 5; the selected micro / nano fiber was a multimode fiber (Corning, 62.5 / 125μm), obtained by mechanical stretching under flame heating, and the diameter of the waist region 4 of the micro / nano fiber was [missing information]. about.

[0051] 1. Preparation process

[0052] A Nafion-CV solution was prepared by mixing 0.01 M crystal violet (CV) with 1 mL Nafion 117 solution. The waist region 4 of the micro / nano fiber was bent into a ring, and the tapered transition regions 3-1 and 3-2 of the micro / nano fiber were brought together to obtain a closed-loop micro / nano fiber cantilever beam frame. The closed-loop micro / nano fiber cantilever beam frame was completely immersed in the Nafion-CV solution and kept there for a period of time. The micro / nano fiber cantilever beam frame was removed from the Nafion-CV solution. Due to the surface tension of the liquid, a Nafion-CV film 5 was naturally formed on the micro / nano fiber cantilever beam frame to encapsulate it. The sensor was left to stand for a period of time to allow the Nafion-CV film 5 to solidify, thus obtaining a micro / nano fiber olfactory sensor based on the Nafion-CV film.

[0053] 2. Working principle

[0054] CV is a pH indicator. When water molecules diffuse into the Nafion-CV film, the acidity of the sulfonate groups weakens, causing the CV molecules to transition from a deprotonated state to a monoprotonated / deprotonated state, thus changing the Nafion-CV film from yellow to green. Figure 5As shown, its spectral absorption peak will shift from 400 nm to 620 nm, causing the micro-nano fiber to undergo evanescent wave absorption related to water molecule concentration. This manifests as the evanescent wave absorption of the micro-nano fiber near the 620 nm wavelength becoming increasingly intense as the water molecule concentration increases. Consequently, the signal transmitted from the light source 1 to the detector 6 via the micro-nano fiber changes, and the relative humidity in the environment can be obtained based on this.

[0055] 3. Olfactory test

[0056] In this embodiment, the micro / nano fiber optic olfactory sensor based on Nafion-CV thin film is placed in environments with different relative humidity levels, and the optical transmittance of the micro / nano fiber at a wavelength of 620 nm is monitored. Figure 6 As shown, the Nafion-CV thin film can effectively respond to relative humidity from 10% to 100%. The sensor's response sensitivity to relative humidity is defined as S. c = ΔT / ΔC, where ΔT is the change in the optical transmittance of the sensor and ΔC is the change in the relative humidity of the environment. The sensor's sensitivity to relative humidity reaches 1.3% / %RH (30%-90% RH), and the system noise is about 0.1%. Therefore, the sensor's detection limit for relative humidity can reach 0.08%, which shows that the sensor has a very high sensitivity to humidity.

[0057] like Figure 7 As shown, the humidity response and recovery time of the micro-nano fiber optic olfactory sensor based on Nafion-CV film were tested using rapidly changing relative humidity. The results showed that the response time was 100 ms and the recovery time was 3.1 s, indicating that the sensor has a very fast response speed to humidity.

[0058] This invention is highly customizable and scalable. It can be used with different gas-sensitive thin-film encapsulated micro-nano optical fibers to achieve different types of gas sensing according to actual application needs. In addition, through the array design of the sensor, it can be used for real-time monitoring and analysis of complex gas components, further improving the performance of the sensor.

[0059] The above are preferred embodiments of the present invention and are not intended to limit the invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A micro / nano fiber optic olfactory sensor based on evanescent wave absorption, characterized in that: The device includes, in sequence, a light source (1), an unstretched portion (2) of a micro / nano fiber, a tapered transition region (3) of a micro / nano fiber, a waist region (4) of a micro / nano fiber, another tapered transition region (3) of a micro / nano fiber, and a detector (7); the unstretched portion (2), tapered transition region (3), waist region, tapered transition region (3), and unstretched portion (2) of the micro / nano fiber are integrated, and the two tapered transition regions (3) of the micro / nano fiber are fitted together. The light source (1) and detector (7) are respectively connected to the two ends of the micro-nano fiber. The two tapered transition regions (3) and waist region (4) of the micro-nano fiber are encapsulated by a flexible film (5). The flexible film (5) is doped with a gas molecule indicator (6). The evanescent wave transmitted on the surface of the micro-nano fiber is sensitive to the optical absorption characteristics of the flexible film (5) and will generate evanescent wave absorption related to gas concentration, thereby realizing the detection of gas concentration. The flexible film (5) has the ability to permeate and release gas molecules.

2. The micro / nano fiber optic olfactory sensor based on evanescent wave absorption according to claim 1, characterized in that: The gas molecule indicator (6) is uniformly dispersed in the flexible film (5) to form a gas-sensitive film.

3. The micro / nano fiber optic olfactory sensor based on evanescent wave absorption according to claim 1 or 2, characterized in that: The refractive index of the flexible thin film (5) is less than that of the micro / nano optical fiber.

4. The micro / nano fiber optic olfactory sensor based on evanescent wave absorption according to claim 3, characterized in that: The thickness of the flexible film (5) is less than or equal to 100 μm.

5. The micro / nano fiber optic olfactory sensor based on evanescent wave absorption according to claim 1, 2, or 4, characterized in that: The waist region (4) of the micro-nano optical fiber has a diameter of less than 10 μm, and the maximum diameter of the ring formed by bending the waist region (4) is less than 1 mm.

6. The micro / nano fiber optic olfactory sensor based on evanescent wave absorption according to claim 5, characterized in that: The detection principle of the micro-nano fiber optic olfactory sensor based on evanescent wave absorption is as follows: gas molecules diffuse into the flexible film (5), thereby changing the pH of the flexible film; the gas molecule indicator (6) changes its color according to the pH of the flexible film (5), thereby changing the optical absorption characteristics of the flexible film (5); the evanescent waves on the surfaces of the two conical transition regions (3) and waist regions (4) of the micro-nano fiber are transmitted in the flexible film (5); when the optical absorption characteristics of the flexible film (5) change due to the gas concentration, the evanescent waves transmitted on the surface of the micro-nano fiber will generate evanescent wave absorption related to the gas concentration; the gas concentration can be obtained by detecting the change in the light signal output by the detection light source (1) after being transmitted through the micro-nano fiber and input into the detector (6), thereby realizing the detection of gas, i.e., olfaction.

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