CN105973807A - Optical fiber sensing probe for detecting gas and liquid - Google Patents

Abstract

The invention discloses an optical fiber sensing probe that can be used to detect gas and liquid and a preparation method thereof. The sensing optical fiber used in the invention has a micro-hole structure, and a micro-hole is opened on one side of the end, and the other end is coated with a reflective film. It can constitute an optical fiber sensing probe for detecting gas and liquid. The optical fiber sensing probe can be combined with a Y-shaped optical fiber, an optical circulator or an optical coupler to form an optical fiber sensor, and can also be combined with a light source and a detector to form an optical fiber sensing system. The invention has the advantages of high integration, simple processing, sample pool located inside the optical fiber, high signal stability and adjustable sensing area length, etc. The invention can be used in various fields such as environmental detection, food detection, medical detection, etc. Liquid detection.

Description

An optical fiber sensing probe that can be used to detect gas and liquid

(1) Technical field

The invention is an all-optical and highly integrated optical fiber sensing probe, in particular to an optical fiber sensing probe which can be used to detect gas and liquid and a preparation method thereof.

(2) Background technology

Optical fiber sensors have been widely used in various gases and liquids for ions, biomolecules, drugs, various dissolved Inert gases, etc. are detected.

Optical fiber gas sensors or optical fiber liquid sensors can be divided into spectral absorption type, fluorescent type, dye indicator type, refractive index change type and evanescent wave type according to their different sensing principles. Over the years, people have continuously improved the structure of fiber-optic gas sensors or fiber-optic liquid sensors according to their needs. However, although these improvements have improved the sensitivity of fiber-optic sensors, there are still many problems, such as the measurement system is more complicated, the optical components are more Many, high cost, poor stability and other shortcomings. Moreover, these optical fiber gas or liquid sensors all need the help of an external reaction cell to complete the sensing reaction, which makes the sensitive layer or core of the optical fiber open during the sensing process of the sensor sensor probe, thus causing the sensing part of great fragility. For example, in 2009, Fuzhou Gaoyi Communication Co., Ltd. designed an optical fiber sensor structure by Wu Li et al. In this structure, a tapered optical fiber is placed in a three-section capillary sleeve to construct a closed gas or liquid sensing cavity. The generated fluorescence or Raman light detects the gas or liquid to be measured, which simplifies the structure of the optical fiber gas sensor or the optical fiber liquid sensor. However, these optical fiber gas or liquid sensing probes are mainly constructed based on ordinary single-mode optical fiber or multi-mode standard optical fiber as the conducting medium. The sensor probe based on the traditional optical fiber structure has a limited load capacity and it is difficult to improve the sensitivity. In 2010, Yuan Libo et al. proposed an evanescent field biochemical sensor based on an inner wall waveguide capillary fiber. Using an inner wall waveguide capillary fiber to construct an optical sensing cavity, a fiber online evanescent sensor with large sensing area and high structural integration was constructed. field biochemical sensor. However, the optical fiber side-section coupling technology must be used for the input and output optical signals, and the sample outlet must be connected to a vacuum pump, which not only complicates the system structure, but also increases the volume of the instrument, making it difficult to utilize the portability and high integration of optical fiber sensors constructed with capillary optical fibers. Advantage. The documents and reports related to the technology of the present invention include: [1] Wu Li, Chen Yanping, Sun Chaoyang, Ling Jiwu. A fiber sensor structure [Z]. CN101587077A: Fuzhou Gaoyi Communication Co., Ltd., 2009. [2] Court Li Bo, Yang Xinghua, Zhang Tao. An evanescent field biochemical sensor based on inner wall waveguide capillary optical fiber[Z].CN101900682A: Harbin Engineering University, 2010

(3) Contents of the invention

The problem to be solved by the present invention is to provide an optical fiber sensor probe that can be used to detect gas and liquid, which can be easily combined with Y-shaped optical fiber, optical circulator or optical coupler to form an optical fiber sensor device, or Combining light source and detector constitutes a fiber optic sensing system. It is characterized by using a special optical fiber with a micro-channel structure to open micro-holes on the side of the light-incident end, using capillary action to inhale gas or liquid to construct a built-in sensing cavity, and coating a reflective film on the end-face of the light-emitting end to reflect the light back to the sensor. Special optical fiber, and then complete light incident, sensing, and reflection in a section of optical fiber at the same time, forming a highly integrated all-fiber sensing probe. Further, the inner surface of the special optical fiber microchannel can be modified with sensitive layers, such as biological probes, chemical sensitive layers, fluorescent indicators or quantum dots, etc., or the sensitive layer can not be modified. The optical fiber is a special optical fiber with a micro-channel structure, such as a capillary optical fiber, a photonic crystal optical fiber, and the like.

In order to achieve the above object, the technical solution of the present invention is: an optical fiber sensing probe that can be used to detect gas and liquid. The optical fiber has at least one micro-channel structure, and there is a hole connected to the micro-channel on the side of the light incident end. Air holes, so when the optical fiber is inserted into the gas and liquid to be measured, the capillary action will cause the gas and liquid to be measured to enter the micropore. When the optical signal is transmitted in all or part of the bare core, the evanescent wave on the surface of the core excites the gas or liquid material around it to obtain fluorescence or Raman light, and the optical signal with sensing information passes through the coated reflective film The end face is reflected back to the detector or spectrometer for analysis and processing, and the detection result is obtained.

Coating the reflective film on the exit end of the optical fiber does not affect the entry of gas and liquid into the optical fiber sensing probe, so the same section of optical fiber can be used to complete: the transmission of the incident light signal, the interaction between the optical signal and the substance to be measured in the built-in sensing cavity of the optical fiber, The return of the sensing signal. The method is simple, ingenious and highly integrated.

The optical fiber sensing probe can be combined with Y-type optical fiber, optical circulator or optical coupler to form an optical fiber sensor or optical fiber sensing network, for example, Y-type optical fiber is used: the optical fiber is used to connect the light source to the optical isolator, and the optical isolator The outgoing fiber is connected to the incident end of the Y-shaped fiber, and the outgoing port of the Y-shaped fiber is connected to the above-mentioned optical fiber sensing probe through fusion splicing or fusion tapering, and the other port of the Y-shaped fiber is connected to the spectrometer for detecting reflected light light signal.

The technical advantage of the invention is that the sample pool is located inside the optical fiber, so the sensitive layer is protected from external damage, the signal stability is high, and the length of the sensing area is adjustable, which can constitute a real-time online optical fiber gas or liquid sensor with simple structure, light weight and high integration .

(4) Description of drawings

Figure 1 is a capillary fiber end view

Figure 2 is a structural diagram of the fiber optic sensing probe

Fig.3 Side sectional view of fiber optic sensing probe

Fig. 4 is the schematic diagram of embodiment 1 of the present invention;

Fig. 5 is the schematic diagram of embodiment 2 of the present invention;

Fig. 6 is a schematic structural view of an optical fiber sensing probe in Embodiment 3 of the present invention;

Fig. 7 is the schematic diagram of embodiment 3 of the present invention;

(5) Specific implementation methods

The present invention will be further described in conjunction with the accompanying drawings and specific embodiments.

The optical fiber sensor probe of the present invention is mainly used for detecting gas and liquid. When used, it needs to be connected with an optical fiber through a coupling method such as welding or fusion taper to form an optical fiber sensor. The optical fiber device for light transmission can use Y-shaped optical fiber, optical circulator or optical Couplers, etc., can also use discrete optical transmission devices as needed.

Implementation case 1: Gas and liquid optical fiber sensor combined with Y-shaped optical fiber

In this example, the special optical fiber constituting the gas and liquid optical fiber sensing probe 5 is illustrated by taking a capillary optical fiber with a micro-channel structure as an example. The structure of the capillary fiber is shown in FIG. 1 , where 501 is the air cavity of the capillary fiber, 502 is the ring core of the capillary fiber, and 503 is the cladding of the capillary fiber. The refractive index of the core 502 of the capillary fiber is higher than that of the cladding 503 , and the capillary fiber can bind the incident light beam within the numerical aperture in the annular core 502 for transmission by using the principle of total reflection.

A kind of manufacturing method of gas, liquid optical fiber sensing probe among the present invention is as shown in Figure 2, and one end of capillary optical fiber is light incident end 4, and the other end end face forms reflective end by chemical silver mirror reaction plating reflective film 6, and when light incident A microhole 7 is opened near the end 4, and the microhole 7 goes deep into the capillary fiber and communicates with the central air hole 501. The side sectional view is shown in FIG. 3 , when the light is incident from the incident end 4 of the capillary fiber, it is transmitted in the annular core 502 , transmitted to the reflective end, reflected by the reflective film 6 , and transmitted from the annular core 502 to the incident end 4 again.

Figure 4 shows the application of the present invention. In this example, connecting the gas and liquid optical fiber sensor probe 5 with the Y-shaped optical fiber can form a gas and liquid optical fiber sensor. Combined with the light source, optical isolator (used to isolate reflected light and avoid interference with incident light), the detector can form a gas and liquid optical fiber sensing system. The upper end of the Y-shaped optical fiber has two branches 301 and 303, and the lower end has a branch 302. The branch 301 is sequentially connected with the optical isolator 2 and the light source 1 as the light incident end. Connect the Y-shaped fiber branch 302 to the incident end 4 of the capillary fiber, and connect the branch 303 to the detector 9 . The optical signal emitted by the light source 1 is incident on the port of the Y-shaped optical fiber 301 through the optical isolator 2 , and simultaneously enters the branch 302 and the branch 303 , and the light entering the branch 303 is transmitted to the detector 9 . The light entering the branch 302 enters the capillary fiber through the incident end 4 of the probe. Place one end of the capillary optical fiber coated with reflective film 6 in the liquid or gas 8 to be measured. Since there is a micropore 7 near the light incident end 4 of the capillary optical fiber, the capillary action makes the liquid or gas 8 to be measured enter the center of the capillary optical fiber In the air hole 501. The gas and liquid to be tested interact with the evanescent wave in the annular core, which changes the intensity of the evanescent wave and the behavior of the light field. The changed optical signal is transmitted to the exit end of the capillary fiber and reflected by the reflective film 6. Branch 302 enters branch 301 and branch 303. The reflected light entering branch 301 is isolated by the optical isolator 2 and cannot continue to transmit, thereby avoiding interference to the optical signal of the light source, while the reflected light entering branch 303 is transmitted to the detector 9. Therefore, the incident light and reflected light information can be detected in the detector 9 at the same time, and the detection of characteristic parameters such as the component and concentration of the liquid or gas to be tested can be realized through comparison.

Implementation case 2: Gas and liquid optical fiber sensors combined with optical circulators

In this example, the special optical fiber constituting the gas and liquid optical fiber sensing probe 5 still uses the capillary optical fiber as shown in Figure 2. The manufacturing method of the sensing probe is as described in Case 1, and the side sectional view is shown in Figure 3.

FIG. 5 shows the application of the present invention. In this example, a gas and liquid optical fiber sensor can be formed by combining the gas and liquid optical fiber sensor probe with the optical circulator 3 . Combined with the light source 1 and the detector 9, a gas and liquid optical fiber sensing system can be formed. The optical circulator 3 has three branches, the 301 port of the optical circulator is connected to the light source 1, the 302 port of the optical circulator is coupled with the incident end 4 of the optical fiber sensing probe through fusion splicing or fusion taper, etc., and the 303 port of the optical circulator The port is connected to the detector 9. In this optical circulator 3, the light transmission direction is counterclockwise, that is, the light emitted by the light source 1 is incident through the branch 301, and enters the capillary fiber from the incident end 4 of the optical fiber sensing probe through the branch 302. One end of the capillary optical fiber coated with reflective film 6 is placed in the liquid or gas 8 to be measured. Since there is a micropore 7 near the light incident end 4 of the capillary optical fiber, the capillary action makes the liquid or gas 8 to be measured enter the center of the capillary optical fiber. In the air hole 501. The evanescent wave entering the capillary optical fiber ring core 502 interacts with the gas and liquid to be measured, changing the intensity of the evanescent wave and the light field. The changed optical signal is transmitted to the capillary optical fiber reflection film 6 and then returns, and is transmitted from the branch 303 of the circulator to the detector 9 in a counterclockwise direction, so as to obtain the characteristic parameters such as the characteristic signal, molecular structure and concentration of the component to be measured, Check this out.

Implementation Case 3: Optical Fiber Sensing Probe with Sensitive Layer Modified on the Inner Surface of Microchannel

In this example, the special optical fiber constituting the gas and liquid optical fiber sensing probe 5 still adopts the capillary optical fiber as shown in FIG. 2 . The manufacturing method of the sensor probe is shown in Figure 6. One end of the capillary fiber is used as the light incident end 4, and the other end is coated with a reflective film 6 as the reflection end, and a microhole 7 is opened near the light incident end 4, and the microhole 7 goes deep into the capillary fiber. It communicates with the central air hole 501. A specific sensitive layer 10 is modified on the inner surface of the capillary optical fiber annular core 502, and the sensitive layer 10 can be a biological probe, a chemical sensitive layer, a fluorescent indicator or a quantum dot, etc. The sensitive layer 10 should have the following characteristics: when encountering a certain gas or liquid to be tested, its light transmission characteristics will change, so the detection of the gas or liquid to be tested can be realized by detecting the change of the optical signal.

Figure 7 shows the application of the present invention. In this example, combining the incident end 4 of the gas and liquid optical fiber sensing probe with the branch 302 of the optical circulator can constitute a gas and liquid optical fiber sensor. Then use the light source 1 and the detector 9 to form a gas and liquid optical fiber sensing system. The branch 301 of the optical circulator is connected to the light source 1, the branch 302 of the optical circulator is coupled and connected to the incident end 4 of the optical fiber sensing probe through fusion or fusion taper, and the branch 303 of the optical circulator is connected to the detector 9. One end of the capillary optical fiber coated with reflective film 6 is placed in the liquid or gas 8 to be tested. Since there is a micropore 7 near the light incident end 4 of the capillary optical fiber, capillary action makes the liquid or gas 8 to be detected enter the capillary optical fiber. In the central air hole 501. In this optical circulator 3, the direction of light transmission is counterclockwise, that is, the light emitted by the light source 1 is incident through the branch 301, incident through the branch 302 from the incident end 4 of the optical fiber sensing probe, and enters its surface through the capillary fiber ring core 502 In the modified sensitive layer 10, when the sensitive layer 10 encounters a specific gas or liquid to be tested, the evanescent wave intensity and light field transmitted in it will change, such as: rabbit anti-SEB can be fixed inside the optical fiber to monitor Cy5 labeling Goat anti-SEB; fixed polyclonal antibody O157:H7, detection of Cy3-labeled secondary antibody to achieve simultaneous detection of staphylococcus enteromycin and E. coli, etc. After the optical signal carrying the specific gas and liquid information to be measured is reflected by the reflective film 6 of the optical fiber sensing probe, the branch 302 of the circulator enters the branch 303 in the counterclockwise direction and is transmitted to the sensor 9, thereby obtaining the component to be measured Characteristic parameters such as characteristic signal, molecular structure, concentration, etc.

The other optical fibers in the optical path above except the capillary optical fiber may be single-mode optical fibers or multi-mode standard optical fibers.

In the three cases of the present invention, capillary optical fibers are used for illustration, and other special optical fibers with micro-channel structures inside can also be used, such as photonic crystal optical fibers, side-hole optical fibers, etc., through micro-holes on the side, and reflective coating on the end surface to construct gas and liquid optical fibers. sense probe.

In the three cases of the present invention, one gas and liquid optical fiber sensing probe is used for illustration, and multiple sensing probes can also be used to construct a multi-probe optical fiber gas or liquid sensor or sensing system.

Although the invention has been particularly shown and described in connection with preferred embodiments, it will be understood by those skilled in the art that changes may be made in form and detail of the invention without departing from the spirit and scope of the invention as defined by the appended claims. All changes are within the protection scope of the present invention.

Claims (9)

1. the optical fiber sensing probe that can be used for detected gas, liquid, produced evanescent wave by input optical signal in a fiber and encourage gas to be measured or liquid, obtain fluorescence or Raman light, utilize the fluorescence described in reflecting and collecting or Raman light, spectrum analysis or process is carried out again, it is thus achieved that result of detection by detector.It is characterized in that: described optical fiber sensing probe has microchannel structure, optical fiber input end side surface has micropore, and micropore is deep to optical fiber microchannel；Optical fiber other end end face plating reflectance coating constitutes reflection end.Probe reflection end inserts gas to be measured or liquid, utilizes capillarity draw gas, liquid to enter in fibre-optical probe microchannel.

A kind of optical fiber sensing probe that can be used for detected gas, liquid the most according to claim 1, it is characterised in that: incidence end side opening micropore, micropore is deep to optical fiber microchannel；Optical fiber other end end face plating reflectance coating constitutes reflection end.

A kind of optical fiber sensing probe that can be used for detected gas, liquid the most according to claim 1, it is characterised in that: described fibre-optical probe can be any special optical fibers with microchannel structure such as capillary fiber, photonic crystal fiber, side-hole fiber.

4. according to the microchannel structure described in claim 1 and 3, it is characterised in that: gas to be measured, liquid are sucked in fibre-optical probe microchannel by available capillarity, constitute and do not allow flimsy built-in sensing chamber.

A kind of optical fiber sensing probe that can be used for detected gas, liquid the most according to claim 1, it is characterised in that: described probe microchannel inner surface can modify sensitive layer, and utilizes sensitive layer to detect specific gas, liquid；Also can not modify sensitive layer, utilize light evanescent wave variation characteristic that gas, liquid are detected.

Sensitive layer the most according to claim 5, it is characterised in that: after running into specific gas to be measured, liquid, its biography light characteristic changes, and therefore can be realized gas, the detection of liquid by detection optical signal feature.

7. according to the sensitive layer described in claim 5 and 6, it is characterised in that: sensitive layer can be bioprobe, chemical sensitive layer, fluorescence indicator or quantum dot etc..

A kind of optical fiber sensing probe that can be used for detected gas, liquid the most according to claim 1, it is characterized in that: this optical fiber sensing probe can be connected with the like such as y-type optical fiber, fiber coupler, optical fiber circulator, constitutes gas, liquid fiber sensor.

Gas the most according to claim 8, liquid fiber sensor, it is characterised in that: an optical fiber sensing probe of the present invention can be used to constitute, it is possible to use multiple optical fiber sensing probe of the present invention to constitute simultaneously.