CN211347927U - Optical fiber LMR humidity sensor and sensing system - Google Patents
Optical fiber LMR humidity sensor and sensing system Download PDFInfo
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- CN211347927U CN211347927U CN201922168156.1U CN201922168156U CN211347927U CN 211347927 U CN211347927 U CN 211347927U CN 201922168156 U CN201922168156 U CN 201922168156U CN 211347927 U CN211347927 U CN 211347927U
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Abstract
The utility model provides an optic fibre LMR humidity transducer and sensing system, the sensor is including reflection formula optic fibre probe, reflection formula optic fibre probe adopt multimode fiber, be equipped with titanium dioxide/polystyrene sodium sulfonate (TiO) outside to by interior in proper order on multimode fiber removes the exposed fibre core of covering2/PSS) film, graphene oxide/Polyethyleneimine (PEI) humidity sensitive film. By using TiO2The characteristic of looseness and porosity of/PSS, and the strong adsorption capacity and the analysis capacity of oxygen-containing functional groups, such as epoxy groups, hydroxyl groups and carboxyl hydrogen bonds, contained in the graphene oxide on water molecules, so that the interaction between the sensor film and the water molecules is enhanced, and the measurement sensitivity is improved; the utility model disclosesCompared with a common optical fiber humidity sensor, the optical fiber humidity sensor has higher sensing sensitivity and stability, can monitor in real time, has a compact structure, and can be widely applied to humidity measurement in industries, families, medical treatment, food production and special environments.
Description
Technical Field
The utility model relates to a humidity transducer technical field, concretely relates to optic fibre LMR humidity transducer and sensing system.
Background
Incident light enters an optical fiber at a certain incident angle, light waves are normally totally reflected (the refractive index of a fiber core is larger than that of a cladding) in an area without a film coating, evanescent waves are formed in the cladding, and in the cladding removing area, because a layer of film material with the refractive index larger than that of the fiber core is coated on the coating removing area, a part of light waves can penetrate out of the fiber core, propagate in the film and are totally reflected, and when the part of light waves meet a certain phase matching condition, the coupling resonance can be generated with the evanescent waves in the cladding. The LMR effect generated by the Crisman-based device is the same, when the effective refractive index of the evanescent wave is matched with the effective refractive index of the loss mode wave, the evanescent wave and the loss mode wave are coupled to the maximum extent, the minimum transmission light intensity is detected, and the excited LMR effect is most obvious. The optical fiber LMR sensor has the advantages of simple manufacture, low cost, easy miniaturization, electromagnetic interference resistance and the like, and is widely applied to the field of physical and chemical detection.
Loss Mode Resonance (LMR) humidity sensors have attracted significant attention in humidity detection due to their high sensitivity and low susceptibility to temperature cross-interference. The surrounding medium interacts with the LMR excitation film, so that the refractive index of the film is changed, the resonance angle or the resonance wavelength is shifted, and the detection of external humidity change can be realized. Compared with the traditional LMR humidity sensor based on the prism, the optical fiber LMR humidity sensor has the characteristics of simple manufacture, low cost, small sensing structure, temperature change interference resistance and electromagnetic interference resistance. However, the conventional optical fiber humidity sensing mainly depends on detecting the transmitted light power, i.e. the light loss after the optical fiber and water molecules act to realize the humidity measurement, and lacks high sensitivity enough to detect the humidity change in the lower range, and causes the disadvantage that the sensor is susceptible to the environmental interference, therefore, there is still a need to further improve the sensitivity and stability of the sensor, which helps to expand the application range of the sensor.
SUMMERY OF THE UTILITY MODEL
Sensitivity, the lower problem of stability in order to solve current optic fibre humidity, the utility model provides an optic fibre LMR humidity transducer and sensing system, the utility model discloses utilize loose porous TiO humidity transducer and sensing system2The absorption of the/PSS film on water molecules and the strong absorption capacity and the strong analysis capacity of oxygen-containing functional groups contained in the graphene oxide, such as epoxy groups, hydroxyl groups and carboxyl hydrogen bonds, on the water molecules further promote the interaction of the optical fiber humidity probe and the surrounding water molecules, improve the measurement sensitivity, and reduce the temperature cross sensitivity in the humidity detection process by utilizing the insensitivity of the LMR sensor on temperature.
The utility model provides a technical scheme that its technical problem adopted is: an optical fiber LMR humidity sensor comprises a reflective optical fiber probe, wherein the reflective optical fiber probe adopts a multimode optical fiber, and a titanium dioxide/sodium polystyrene sulfonate (TiO) is sequentially arranged on a bare fiber core of the multimode optical fiber without a plastic cladding from inside to outside2/PSS) film, graphene oxide/Polyethyleneimine (PEI) humidity sensitive film.
Further, the surface of the fiber core is fixed with titanium dioxide/sodium polystyrene sulfonate (TiO) by an electrostatic layer-by-layer self-assembly method2/PSS) film.
Further, the graphene oxide/polyethyleneimine humidity-sensitive membrane is fixed on the surface of the titanium dioxide/sodium polystyrene sulfonate membrane by a static layer-by-layer self-assembly method.
Furthermore, the core diameter of the multimode optical fiber is 600 microns, and the sensing length of the fiber core without the plastic cladding is 1.5-2 cm.
Furthermore, the number of the layers of the titanium dioxide/sodium polystyrene sulfonate film is 1-15, and the thickness is 50-500 nm.
Preferably, the number of the titanium dioxide/sodium polystyrene sulfonate thin film layers is 7, the thickness is 250nm, the sensitivity of the sensor is highest, and the measurement accuracy is highest.
Furthermore, the number of the graphene oxide/polyethyleneimine humidity-sensitive film layers is 1-10, and the thickness is 20-250 nm.
Preferably, the number of the graphene oxide/polyethyleneimine humidity-sensitive membrane layers is 5, and when the thickness of the graphene oxide/polyethyleneimine humidity-sensitive membrane layer is 50nm, the sensitivity of the sensor is highest, and the measurement accuracy is highest.
Further, TiO in the titanium dioxide/sodium polystyrene sulfonate film2The diameter of the nanoparticles is 21-50 nm.
Further, the multimode optical fiber end face is coated with a silver film to achieve reflection of light, and terminated with polyacrylate to prevent the silver film from falling off.
Further, the thickness of the silver film is 25-100 nm.
A sensing system formed based on the optical fiber LMR humidity sensor comprises an optical fiber LMR humidity sensor with a Y-shaped optical fiber as a light path, wherein the input end of the optical fiber LMR humidity sensor is connected with a broadband light source with a spectrum in a visible light waveband, the output end of the optical fiber LMR humidity sensor is connected with a broadband spectrometer, the broadband spectrometer is connected to an external computer through a data interface, and the optical fiber LMR humidity sensor is arranged in a system to be measured.
Compared with the prior art, the utility model beneficial effect be:
1. the utility model utilizes TiO2The loose and porous characteristic of the/PSS, and the strong adsorption capacity and the resolving capacity of oxygen-containing functional groups, such as epoxy groups, hydroxyl groups and carboxyl hydrogen bonds, contained in the graphene oxide to water molecules, so that the sensor has the advantage of high sensitivity;
2. the utility model discloses an optic fibre LMR sensor has very low sensitivity to temperature variation, the reason is the low sensitivity that loss mode effect (LMR) embodied to temperature variation, consequently the temperature can not lead to the removal of LMR resonance wavelength in humidity detection, and then reduces humidity transducer and to temperature variation's cross sensitivity, improves measurement stability and accuracy;
the utility model discloses optic fibre LMR humidity transducer based on oxidation graphite alkene and Polyethyleneimine (PEI) sensitization has higher sensitivity and stability, can real-time supervision, and its compact structure can wide application industry, family, medical treatment, food production and special environment under the humidity measurement.
Drawings
Fig. 1 is a schematic structural diagram of an optical fiber LMR humidity sensor according to the present invention;
FIG. 2 is a schematic structural view of a sensing system formed by the fiber LMR humidity sensor of the present invention;
FIG. 3 is a reflection spectrogram of humidity measurement in an embodiment of the present invention;
fig. 4 is a linear fitting curve of the measurement result in the embodiment of the present invention;
reference numerals: 1. fiber core, 2 fiber cladding, 3, titanium dioxide/sodium polystyrene sulfonate (TiO)2(PSS) membrane, 4, graphene oxide/PEI membrane, 5, silver membrane, 6, polyacrylate;
1 ', a broadband light source, 2 ', a Y-shaped optical fiber, 3 ', an optical fiber LMR humidity sensor based on graphene oxide and Polyethyleneimine (PEI) sensitization, 4 ', a closed humidity measurement experiment box, 5 ' and a spectrometer.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.
Examples
An optical fiber LMR humidity sensor is shown in figure 1 and comprises a reflective optical fiber probe, wherein the reflective optical fiber probe adopts a multimode optical fiber with the core diameter of 600 μm, and a titanium dioxide/sodium polystyrene sulfonate (TiO) is sequentially arranged on a bare fiber core 1 of the multimode optical fiber without a cladding 2 from inside to outside2/PSS) membrane 3, graphene oxide/Polyethyleneimine (PEI) humidity-sensitive membrane 4, end-coated with silver membrane 5 to achieve reflection of light, and capped with polyacrylate 6 to prevent shedding of the silver membrane.
Wherein the sensing length of the fiber core without the plastic cladding is 1.5-2 cm; the number of the titanium dioxide/sodium polystyrene sulfonate film layers is 1-15, and the thickness is 50-500 nm; the number of the graphene oxide/polyethyleneimine humidity-sensitive film layers is 1-10, and the thickness is 20-250 nm; the thickness of the silver film is 25-100 nm; TiO in the titanium dioxide/sodium polystyrene sulfonate film2The diameter of the nanoparticles is 21-50 nm.
As shown in fig. 2, the sensing system formed based on the optical fiber LMR humidity sensor includes an optical fiber LMR humidity sensor 3 'using a Y-type optical fiber 2' as a light path, an input end of the optical fiber LMR humidity sensor is connected to a broadband light source 1 'having a spectrum in a visible light band, an output end of the optical fiber LMR humidity sensor is connected to a broadband spectrometer 5', the broadband spectrometer is connected to an external computer through a data interface, and the optical fiber LMR humidity sensor 3 'is disposed in a closed humidity-adjustable measurement box 4'.
The preparation method of the optical fiber LMR humidity sensor based on graphene oxide and Polyethyleneimine (PEI) sensitization comprises the following steps:
(1) preparation of unclad reflective optical fiber
Taking a plastic cladding of 1.5-2 cm from one end of a 10cm optical fiber to serve as a sensing area of a probe, sequentially cleaning a fiber core by using ethanol, piranha solution (a mixed solution of concentrated sulfuric acid with the mass fraction of 95-98% and hydrogen peroxide with the mass fraction of 30% in a volume ratio of 7: 3) and pure water, soaking in the piranha solution for 1 hour to remove redundant impurities, polishing the end face of the optical fiber by using sand paper with different roughness degrees in order to realize light reflection in the optical fiber probe, depositing a silver film with the thickness of 40nm on the smooth end face of the optical fiber, and blocking the end by using polyacrylate in order to prevent light leakage caused by the falling of the silver film;
(2) TiO plating2PSS film
Using aqueous PSS solution as anionic solution and using TiO after sonication2The nano water dispersion is used as a cationic solution, and the pH value of the anionic and cationic solutions is adjusted to 2.0; in the process of coating using the dip coater, first, the core is dipped into 50mg/ml TiO2Aqueous nano-dispersion (TiO)2The diameter of the nano particles is 21nm) for 3 minutes, then the fiber core is washed by acid deionized water for 1 minute, the non-attached materials on the surface are removed, the drying is carried out for 1 minute, and then the fiber core is immersed into 5mg/ml PSS aqueous solution for 2 minutes;
repeating the above steps for 7 times to obtain TiO2The thickness of the/PSS film is 250 nm;
(3) plated graphene oxide/PEI film
Immersing the probe in 2mg/ml PEI aqueous solution for 5 minutes, washing the probe with deionized water to remove residual medicines, drying in air for 1 minute, immersing the probe in 2mg/ml graphene oxide water or ethanol dispersion for 5 minutes, and washing and drying with deionized water;
and repeating the step for 5 times, wherein the thickness of the graphene oxide/PEI film is 50 nm.
The test for measuring humidity by applying the prepared optical fiber LMR humidity sensor based on graphene oxide and Polyethyleneimine (PEI) sensitization comprises the following steps:
the optical fiber LMR humidity sensor based on graphene oxide and polyethyleneimine sensitization is placed in a humidity measurement test box, a humidifier is controlled to work for 10s in the sensing process, the humidity in the box is increased by about 10%, the humidity can be adjusted according to specific conditions, time is needed for balance of the humidity in the box and measurement of a reference humidity meter, therefore, the humidity in the box is adjusted every time, and after 5 minutes, the reference humidity indicator and a reflection spectrum are recorded at the same time as shown in figure 3.
By performing linear fitting on the measurement results, as shown in fig. 4, the sensitivity of the sensor in the humidity range of 20% RH to 60% RH of 0.49 nm/% RH, the linearity of 0.9444, the sensitivity of the sensor in the humidity range of 60% RH to 90% RH of 2.95 nm/% RH, and the linearity of 0.92071 can be obtained, which is improved by about 300% compared with the sensitivity of the conventional optical fiber humidity sensor.
In conclusion, the optical fiber LMR humidity sensor based on graphene oxide and Polyethyleneimine (PEI) sensitization has higher sensing sensitivity and stability, can monitor in real time, has a compact structure, and can be widely applied to humidity measurement in industries, families, medical treatment, food production and special environments.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. An optical fiber LMR humidity sensor, characterized by: the optical fiber probe comprises a reflective optical fiber probe, wherein the reflective optical fiber probe adopts a multimode optical fiber, and a titanium dioxide/sodium polystyrene sulfonate film and a graphene oxide/polyethyleneimine humidity-sensitive film are sequentially arranged on a bare fiber core of the multimode optical fiber, the cladding of which is removed, from inside to outside.
2. A fiber optic LMR moisture sensor according to claim 1 wherein: fixing the titanium dioxide/sodium polystyrene sulfonate film on the surface of the fiber core by an electrostatic layer-by-layer self-assembly method; the graphene oxide/polyethyleneimine humidity-sensitive membrane is fixed on the surface of the titanium dioxide/sodium polystyrene sulfonate membrane by a static layer-by-layer self-assembly method.
3. A fiber optic LMR moisture sensor according to claim 1 wherein: the core diameter of the multimode optical fiber is 600 mu m, and the sensing length of the fiber core without the plastic cladding is 1.5-2 cm.
4. A fiber optic LMR moisture sensor according to claim 2 wherein: the number of the titanium dioxide/sodium polystyrene sulfonate film layers is 1-15, and the thickness is 50-500 nm.
5. A fiber optic LMR moisture sensor according to claim 2 wherein: the graphene oxide/polyethyleneimine moisture-sensitive membrane comprises 1-10 layers and is 20-250 nm thick.
6. A fiber optic LMR moisture sensor according to claim 2 wherein: the number of the titanium dioxide/sodium polystyrene sulfonate film layers is 7, and the thickness is 250 nm; the number of layers of the graphene oxide/polyethyleneimine humidity-sensitive membrane is 5, and the thickness of the graphene oxide/polyethyleneimine humidity-sensitive membrane is 50 nm.
7. A fiber optic LMR moisture sensor according to claim 1 wherein: TiO in the titanium dioxide/sodium polystyrene sulfonate film2The diameter of the nanoparticles is 21-50 nm.
8. A fiber optic LMR moisture sensor according to claim 1 wherein: the multimode optical fiber end face is coated with a silver film and terminated with polyacrylate.
9. A fiber optic LMR moisture sensor according to claim 8, wherein: the thickness of the silver film is 25-100 nm.
10. A sensing system based on the fiber LMR humidity sensor of any one of claims 1 to 9, characterized in that: the sensing system comprises an optical fiber LMR humidity sensor with a Y-shaped optical fiber as a light path, wherein the input end of the optical fiber LMR humidity sensor is connected with a broadband light source with a visible light wave band, the output end of the optical fiber LMR humidity sensor is connected with a broadband spectrograph, the broadband spectrograph is connected to an external computer through a data interface, and the optical fiber LMR humidity sensor is arranged in the system to be measured.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112557336A (en) * | 2020-12-10 | 2021-03-26 | 中电保力（北京）科技有限公司 | Method for measuring humidity of cable by using double-path infrared spectrum analysis method |
| CN113075165A (en) * | 2021-03-18 | 2021-07-06 | 重庆理工大学 | U-shaped humidity-sensitive optical fiber sensor and manufacturing method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112557336A (en) * | 2020-12-10 | 2021-03-26 | 中电保力（北京）科技有限公司 | Method for measuring humidity of cable by using double-path infrared spectrum analysis method |
| CN112557336B (en) * | 2020-12-10 | 2021-12-24 | 中电保力（北京）科技有限公司 | Method for measuring humidity of cable by using double-path infrared spectrum analysis method |
| CN113075165A (en) * | 2021-03-18 | 2021-07-06 | 重庆理工大学 | U-shaped humidity-sensitive optical fiber sensor and manufacturing method thereof |
| CN113075165B (en) * | 2021-03-18 | 2022-10-18 | 重庆理工大学 | U-shaped humidity-sensitive optical fiber sensor and manufacturing method thereof |
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