CN111551500A - Low-cost optical fiber humidity sensor - Google Patents
Low-cost optical fiber humidity sensor Download PDFInfo
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- CN111551500A CN111551500A CN202010439117.5A CN202010439117A CN111551500A CN 111551500 A CN111551500 A CN 111551500A CN 202010439117 A CN202010439117 A CN 202010439117A CN 111551500 A CN111551500 A CN 111551500A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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Abstract
The invention provides a low-cost optical fiber humidity sensor, wherein a precious metal part is arranged on a humidity sensitive material part; the bare fiber core is arranged on the upper part of the noble metal part, and a gap is arranged between the bare fiber core and the noble metal part. When the optical fiber is used, the humidity sensitive material part absorbs moisture and expands, the distance between the noble metal part and the bare fiber core is reduced, and the coupling between the bare fiber core and the noble metal part is enhanced, so that the transmission characteristic of light from the first optical fiber to the second optical fiber is changed, and the environment humidity detection is realized by detecting the transmission characteristic. The present invention has the advantage of high sensitivity, since the coupling of light propagating in the core to the noble metal portion outside the core is very sensitive to the distance between them. In addition, in the design, only the fiber core needs to be planed, and the preparation of the noble metal part is simpler, so that the method is low in cost and has a good application prospect in the field of humidity detection.
Description
Technical Field
The invention relates to the field of humidity sensing, in particular to a low-cost optical fiber humidity sensor.
Background
Humidity monitoring has important application in the fields of electronic appliances, food storage, aerospace, cultural relic protection and the like. The traditional humidity sensor comprises a hair hygrometer, a wet-dry bulb hygrometer and an electric quantity type hygrometer. The traditional humidity sensor is easily affected by the environment and is not suitable for being applied in severe environment. The optical fiber humidity sensor provides a new means for humidity sensing. The traditional optical fiber humidity sensor needs a dislocated optical fiber or a notched optical fiber, and has the disadvantages of complex equipment, high cost, low sensitivity and low accuracy.
Disclosure of Invention
In order to solve the above problems, the present invention provides a low-cost high-sensitivity optical fiber humidity sensor, which includes a light source, a photodetector, a substrate, a first supporting portion, a second supporting portion, a first optical fiber, a second optical fiber, a coupling portion, a humidity sensitive material portion, and a noble metal portion, wherein the first supporting portion and the second supporting portion are fixed on the substrate, the humidity sensitive material portion is disposed between the first supporting portion and the second supporting portion, the first optical fiber is fixed on the first supporting portion, the second optical fiber is fixed on the second supporting portion, the coupling portion is a bare fiber core, the coupling portion is fixed between two end faces of the first optical fiber and the second optical fiber, the noble metal portion is disposed on the humidity sensitive material portion, a gap is disposed between the noble metal portion and the coupling portion, the first optical fiber is connected to the light source, and the second optical fiber is connected to the photodetector; when the humidity-sensitive material is used, the humidity-sensitive material absorbs moisture and then expands, so that the distance between the noble metal part and the coupling part is reduced, the coupling between the coupling part and the noble metal part is increased, the transmission characteristic of light from the first optical fiber to the second optical fiber is changed, and the ambient humidity detection is realized by detecting the transmission characteristic.
Further, the moisture sensitive material portion is a hygroscopic expansion material.
Further, the moisture sensitive material portion is polyimide.
Further, the noble metal part is a periodic arrangement of noble metal particles.
Furthermore, the material of the noble metal particles is gold, and the particle diameter of the noble metal particles is 20 nm-80 nm.
Further, a noble metal film is provided under the noble metal particles.
Further, the noble metal portion side of the bare core is planar.
Further, the moisture sensitive material portion does not contact the first supporting portion and the second supporting portion.
Furthermore, gold particles are provided on the plane.
The invention has the beneficial effects that: the invention provides a low-cost optical fiber humidity sensor, wherein a precious metal part is arranged on a humidity sensitive material part; the bare fiber core is arranged on the upper part of the noble metal part, and a gap is arranged between the bare fiber core and the noble metal part. When the optical fiber is used, the humidity sensitive material part absorbs moisture and expands, the distance between the noble metal part and the bare fiber core is reduced, and the coupling between the bare fiber core and the noble metal part is enhanced, so that the transmission characteristic of light from the first optical fiber to the second optical fiber is changed, and the environment humidity detection is realized by detecting the transmission characteristic. The present invention has the advantage of high sensitivity, since the coupling of light propagating in the core to the noble metal portion outside the core is very sensitive to the distance between them. In addition, in the design, only the fiber core needs to be planed, and the preparation of the noble metal part is simpler, so that the method is low in cost and has a good application prospect in the field of humidity detection.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of a low cost fiber optic humidity sensor.
Fig. 2 is a schematic view of a periodic arrangement of noble metal particles.
FIG. 3 is a schematic diagram of yet another low cost fiber optic humidity sensor.
In the figure: 1. a substrate; 21. a first support section; 22. a second support section; 31. a first optical fiber; 32. a second optical fiber; 4. a coupling section; 5. a moisture sensitive material portion; 6. a noble metal part; 7. noble metal particles.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the intended purpose, the following detailed description of the embodiments, structural features and effects of the present invention will be made with reference to the accompanying drawings and examples.
Example 1
The invention provides a low-cost optical fiber humidity sensor which comprises a light source, a light detector, a substrate 1, a first supporting part 21, a second supporting part 22, a first optical fiber 31, a second optical fiber 32, a coupling part 4, a humidity sensitive material part 5 and a precious metal part 6. As shown in fig. 1, the first supporting portion 21 and the second supporting portion 22 are fixed on the base 1. The moisture sensitive material portion 5 is disposed between the first supporting portion 21 and the second supporting portion 22. The moisture sensitive material portion 5 is a moisture swellable material, i.e. the moisture sensitive material portion 5 swells upon absorbing moisture. Preferably, the material of the moisture absorbent material portion 5 is polyimide. The first optical fiber 31 is fixed to the first support portion 21, and the second optical fiber 32 is fixed to the second support portion 22. The coupling part 4 is a bare core, i.e. the cladding is removed, leaving only the core. The coupling section 4 is fixed between both end surfaces of the first optical fiber 31 and the second optical fiber 32. The noble metal part 6 is provided on the moisture sensitive material part 5. A gap is provided between the noble metal part 6 and the coupling part 4. When the moisture sensitive material portion 5 swells, the noble metal portion 6 does not contact the coupling portion 4. The first optical fiber 31 is connected to a light source. Preferably, the light source is a continuous spectrum light source. The second optical fiber 32 is connected to the photodetector. The light detector detects the transmission spectrum.
When the humidity-sensitive material is used, the humidity-sensitive material part 5 absorbs moisture and expands, so that the distance between the noble metal part 6 and the bare fiber core is reduced, and the coupling between the bare fiber core and the noble metal part 6 is enhanced, so that the transmission characteristic of light from the first optical fiber 31 to the second optical fiber 32 is changed, and the ambient humidity detection is realized by detecting the transmission characteristic.
The present invention has the advantage of high sensitivity, since the coupling of light propagating in the core to the noble metal portion outside the core is very sensitive to the distance between them. In addition, in the design, only the fiber core needs to be planed, and the preparation of the noble metal part 6 is simpler, so that the method is low in cost and has a good application prospect in the field of humidity detection.
Further, in the present embodiment, the moisture sensitive material portion 5 is in contact with the first supporting portion 21 and the second supporting portion 22, and the first supporting portion 21 and the second supporting portion 22 limit the expansion of the moisture sensitive material portion 5 in the horizontal direction in fig. 1, so that the moisture sensitive material portion 5 expands more in the vertical direction, the distance between the noble metal portion 6 and the bare core is changed more, the transmission spectrum is changed more, and the sensitivity of humidity detection is improved.
Example 2
In example 1, as shown in fig. 2, the noble metal part 6 is a noble metal particle 7 arranged periodically. The material of the noble metal particles 7 is gold, and the particle size of the noble metal particles 7 is 20-80 nm. The material of the noble metal particles 7 is gold, which is more favorable for improving the stability of the material and is not easy to be oxidized in the air. The particle diameter of the noble metal particles 7 is 20 nm to 80 nm so that the resonance wavelength of the noble metal particles 7 is in the visible light band. In this embodiment, light in the bare core is coupled to the noble metal particles 7, causing vibration of the charge in the noble metal particles 7. At a specific wavelength, light in the bare core and the noble metal particles 7 realize surface plasmon resonance, and a valley appears in the transmission spectrum. The signal characteristic makes the detection easier, and the sensitivity of humidity detection is improved in the embodiment because the valley has a certain half-peak width and the transmission coefficient at the valley is closely related to the distance between the noble metal particles 7 and the bare fiber core.
Further, a noble metal film is also provided under the noble metal particles 7 even if a noble metal thin film is provided between the noble metal particles 7 and the humidity sensitive material portion 5. After the noble metal film is arranged on the humidity sensitive material part 5, the noble metal particles 7 are arranged on the noble metal film, so that on one hand, the noble metal particles 7 are ensured to be in one plane, namely, the noble metal particles are not excessively uneven, on the other hand, more light is favorably coupled into a complex of the noble metal particles 7 and the noble metal layer, the transmission coefficient at the resonance wavelength is smaller, the half-peak width is further reduced, and the humidity detection sensitivity is improved.
Further, the noble metal portion 6 side of the bare core is a flat surface. That is, in fig. 1, the lower surface of the intermediate bare core, near the noble metal particles 7, is planed to be a flat surface. When the bare fiber core is planed, the planed plane is close to more noble metal particles 7, which is beneficial to improving the coupling of the bare fiber core and the noble metal particles 7.
Example 3
In addition to example 2, as shown in fig. 3, the moisture sensitive material part 5 is not in contact with the first supporting part 21 and the second supporting part 22. That is, there is a gap between the moisture sensitive material portion 5 and the first supporting portion 21; there is also a gap between the moisture sensitive material portion 5 and the second support portion 22. When the moisture-sensitive material portion 5 absorbs moisture and expands, the moisture-sensitive material portion 5 expands not only in the vertical direction but also in the horizontal direction. This changes not only the distance between the bare core and the noble metal particles 7, but also the spacing between the noble metal particles 7. Preferably, the distance between the noble metal particles is less than 40 nanometers. The change in the pitch between the noble metal particles 7 changes the resonance wavelength of the noble metal particles 7. Therefore, this embodiment also significantly shifts the resonance wavelength of the noble metal particles 7. And the humidity is reflected from the other dimension, so that the detection sensitivity is improved.
Furthermore, the gold particles are arranged on the plane, namely the gold particles are arranged on the plane of the bare fiber core, so that the coupling between the light in the bare fiber core and the noble metal particles 7 is increased, the transmission spectrum is changed more, and the detection sensitivity is improved.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (9)
1. A low cost fiber optic humidity sensor, comprising: the optical fiber coupling device comprises a light source, a light detector, a substrate, a first supporting part, a second supporting part, a first optical fiber, a second optical fiber, a coupling part, a humidity-sensitive material part and a precious metal part, wherein the first supporting part and the second supporting part are fixed on the substrate, the humidity-sensitive material part is arranged between the first supporting part and the second supporting part, the first optical fiber is fixed on the first supporting part, the second optical fiber is fixed on the second supporting part, the coupling part is a bare fiber core, the coupling part is fixed between the end faces of the first optical fiber and the second optical fiber, the precious metal part is arranged on the humidity-sensitive material part, a gap is arranged between the precious metal part and the coupling part, the first optical fiber is connected with the light source, and the second optical fiber is connected with the light detector; when the humidity-sensitive material is used, the humidity-sensitive material portion absorbs moisture and then expands, the coupling between the coupling portion and the precious metal portion is increased, the transmission characteristic of light from the first optical fiber to the second optical fiber is changed, and the ambient humidity detection is realized by detecting the transmission characteristic.
2. The low cost humidity sensor of claim 1, wherein: the moisture sensitive material portion is a hygroscopic intumescent material.
3. The low cost fiber optic humidity sensor of claim 2, wherein: the moisture sensitive material portion is polyimide.
4. The low cost fiber optic humidity sensor of claim 3, wherein: the noble metal part is noble metal particles which are arranged periodically.
5. The low cost fiber optic humidity sensor of claim 4, wherein: the material of the noble metal particles is gold, and the particle size of the noble metal particles is 20-80 nanometers.
6. The low cost fiber optic humidity sensor of claim 5, wherein: and a noble metal film is arranged below the noble metal particles.
7. The low cost fiber optic humidity sensor of any of claims 1-6, wherein: one side of the noble metal part of the bare fiber core is a plane.
8. The low cost fiber optic humidity sensor of claim 7, wherein: the moisture sensitive material portion is not in contact with the first supporting portion and the second supporting portion.
9. The low cost fiber optic humidity sensor of claim 8, wherein: gold particles are also arranged on the plane.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010439117.5A CN111551500A (en) | 2020-05-22 | 2020-05-22 | Low-cost optical fiber humidity sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010439117.5A CN111551500A (en) | 2020-05-22 | 2020-05-22 | Low-cost optical fiber humidity sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111551500A true CN111551500A (en) | 2020-08-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010439117.5A Withdrawn CN111551500A (en) | 2020-05-22 | 2020-05-22 | Low-cost optical fiber humidity sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111551500A (en) |
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2020
- 2020-05-22 CN CN202010439117.5A patent/CN111551500A/en not_active Withdrawn
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Application publication date: 20200818 |