JP7465464B2 - Hetero-core optical fiber sensor device - Google Patents

Description

The present invention relates to a hetero-core optical fiber sensor device.

In recent years, the use of heterocore optical fibers in various sensors has been considered. The heterocore optical fibers have an optical transmission section with a core and a clad, and a heterocore section that is connected to the core and clad of the optical transmission section, but has a core and clad with a different diameter from the core of the optical transmission section.

Conventionally, as a heterocore optical fiber sensor device using a heterocore optical fiber, for example, an optical fiber hydrogen sensor having a photoresponsive section in which nanoparticles of a hydrogen storage material are sparsely fixed to the outer peripheral surface of the cladding of the heterocore section is known (see, for example, Patent Document 1).

JP 2019-32229 A

In the optical fiber hydrogen sensor described in Patent Document 1, the response of the optical response section when it receives light, for example, the proportion of light that leaks from the optical transmission section into the cladding of the heterocore section to the outside, changes depending on the hydrogen concentration around the optical fiber. Therefore, with the optical fiber hydrogen sensor, the hydrogen concentration around the optical fiber can be detected by detecting the degree of absorption of light of a specific wavelength in the heterocore section (and thus the degree of attenuation of the transmission intensity of light of a specific wavelength in the optical fiber).

However, conventional hetero-core optical fiber sensor devices are only capable of detecting a specific compound or the concentration of that compound, and have the disadvantage that it is difficult to detect multiple compounds using a single device.

The present invention aims to provide a hetero-core optical fiber sensor device that can eliminate such inconveniences and detect multiple compounds using a single device.

In order to achieve this object, the heterocore optical fiber sensor device of the present invention is a heterocore optical fiber sensor device comprising a light transmission section having a core and a clad, and a heterocore section having a core and a clad respectively connected to the core and clad of the light transmission section, the core of the heterocore section being an optical fiber having a smaller diameter than the core of the light transmission section, the heterocore optical fiber sensor device being characterized in that a coating film made of a negatively charged lipid is provided on the outer surface of the clad of the heterocore section, and when a compound acting on the negatively charged lipid selected from the group consisting of quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein is present in the external environment around the coating film, the refractive index of the coating film changes due to the action of the compound acting on the negatively charged lipid, and light transmitted through the core of the light transmission section leaks into the clad in the heterocore section, and the compound acting on the negatively charged lipid is detected by measuring the light loss spectrum due to the change in intensity of reflection of the leaked light by the coating film with the changed refractive index.

In the heterocore optical fiber sensor device of the present invention, when light is transmitted through the core of the optical transmission section, the light leaking into the cladding in the heterocore section is reflected by the coating membrane made of the negatively charged lipid. At this time, if a compound that acts on the negatively charged lipid is present in the external environment surrounding the coating membrane, the refractive index of the peritoneal membrane made of the negatively charged lipid changes due to the action of the compound, and as a result, the intensity of the light reflected by the coating membrane changes.

The heterocore optical fiber sensor device of the present invention can detect compounds present in the external environment surrounding the coating film by detecting changes in the intensity of light reflected by the coating film of the heterocore portion. At this time, the change in the refractive index of the peritoneal membrane made of the negatively charged lipids differs depending on the compound that acts on the negatively charged lipids, so multiple compounds can be detected depending on the degree of change in the intensity of light reflected by the coating film of the heterocore portion.

In the hetero-core optical fiber sensor device of the present invention, oleic acid or dioctyl phosphate can be used as the negatively charged lipid.

FIG. 2 is an explanatory cross-sectional view showing the configuration of a sensor unit of the hetero-core optical fiber sensor device of the present invention FIG. 2 is an explanatory diagram showing an example of a device configuration of a hetero-core optical fiber sensor device according to the present invention. 13 is a graph showing optical losses of various compounds detected when the hetero-core optical fiber sensor device of the present invention is provided with a coating film made of oleic acid. 13 is a graph showing the optical loss of each compound detected when the hetero-core optical fiber sensor device of the present invention is provided with a coating film made of dioctyl phosphate. 13 is a graph showing optical loss spectra detected in the hetero-core optical fiber sensor device of the present invention when the sensor device is provided with a coating film made of oleic acid, comparing water with multiple concentrations of quinine. 13 is a graph showing optical loss spectra detected in the hetero-core optical fiber sensor device of the present invention when the sensor device is provided with a coating film made of dioctyl phosphate, comparing the optical loss spectra of water and quinine. A graph showing a comparison of the light loss of each compound detected when the hetero-core optical fiber sensor device of the present invention is provided with a coating film made of oleic acid and the light loss of each compound detected when the hetero-core optical fiber sensor device of the present invention is provided with a coating film made of dioctyl phosphate.

Next, an embodiment of the present invention will be described in more detail with reference to the attached drawings.

As shown in FIG. 1, the heterocore optical fiber sensor device 1 of this embodiment includes a heterocore optical fiber 4 having a heterocore portion 3 of a predetermined length sandwiched between optical transmission portions 2, 2. The optical transmission portion 2 is a multimode optical fiber consisting of a core 5a and a cladding 6a that covers the outer peripheral surface of the core 5a, and the heterocore portion 3 is a single-mode optical fiber consisting of a core 5b that has a smaller diameter than the core 5a and a cladding 6b that covers the outer peripheral surface of the core 5b.

The heterocore optical fiber sensor device 1 has a coating film 7 made of a negatively charged lipid formed on the outer surface of the cladding 6b of the heterocore portion 3. As the negatively charged lipid, for example, oleic acid or dioctyl phosphate can be used.

The peritoneal membrane 7 can be formed, for example, by treating the outer surface of the cladding 6b of the heterocore portion 3 with a 5-20 mM aqueous solution of polylysine to positively charge it, then dropping the negatively charged lipid dispersed in a water-ethanol solution onto the outer surface and leaving it for 20-24 hours. The water-ethanol solution contains, for example, 2.5% by mass of ethanol and, for example, 1% by mass of the negatively charged lipid relative to the total amount of the water-ethanol solution.

As shown in FIG. 2, the heterocore optical fiber sensor device 1 of this embodiment has a light source 22 such as an LFD at one end of the optical fiber 4 when the heterocore portion 3 of the heterocore optical fiber 4 is placed in the detected portion 21, and a detection device 23 such as a spectrum analyzer or spectroscope at the other end of the optical fiber 4. In addition, an analysis device 24 such as a personal computer that analyzes the degree of change in the intensity of the reflected light detected by the detection device 23 is connected to the detection device 23.

In the heterocore optical fiber sensor device 1 of this embodiment, when light introduced from the light source 22 into the optical transmission section 2 is transmitted through the core 5a of the optical transmission section 2, the light leaking into the cladding 6b of the heterocore section 3 is reflected by the coating film 7. At this time, if a compound that acts on the negatively charged lipids is present in the external environment surrounding the coating film 7, the refractive index of the peritoneal membrane 7 made of the negatively charged lipids changes due to the action of the compound, and as a result, the intensity of the light reflected by the coating film 7 changes.

Examples of compounds that act on negatively charged lipids include quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein.

Therefore, according to the heterocore optical fiber sensor device 1 of this embodiment, the change in the intensity of the light reflected by the coating film 7 of the heterocore portion 3 is detected by the detection device 23 and analyzed by the analysis device 24, thereby making it possible to detect compounds present in the external environment surrounding the coating film 7. At this time, the change in the refractive index of the coating film 7 made of the negatively charged lipid differs depending on the compound that acts on the negatively charged lipid, so multiple compounds can be identified as targets for detection based on the degree of change in the intensity of the light reflected by the coating film 7 of the heterocore portion 3.

Next, 11 types of aqueous solutions were prepared, each containing quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein at a concentration of 10 millimolar.

Next, the heterocore portion 3 of the heterocore optical fiber sensor device 1 having a coating film 7 made of oleic acid was immersed in each aqueous solution, white light in the wavelength range of 360-2000 nm was introduced from the light source 22 into the optical transmission portion 2, and the optical loss of each aqueous solution relative to pure water was detected by the detector 23. The results are shown in Figure 3. Furthermore, the optical loss of each aqueous solution relative to pure water was detected in exactly the same manner as in the case of the heterocore optical fiber sensor device 1 having a coating film 7 made of oleic acid, except that the heterocore optical fiber sensor device 1 having a coating film 7 made of dioctyl phosphate was used. The results are shown in Figure 4.

From Figures 3 and 4, it is clear that the hetero-core optical fiber sensor device 1 equipped with a coating film 7 made of oleic acid or a coating film 7 made of dioctyl phosphate detects different optical losses in pure water for quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein, and can distinguish between quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein.

Next, the heterocore portion 3 of the heterocore optical fiber sensor device 1 equipped with a coating film 7 made of oleic acid was immersed in pure water, a 10 mmolar quinine solution, and a 50 mmolar quinine solution, respectively, and white light in the wavelength range of 360-2000 nm was introduced from the light source 22 into the optical transmission portion 2, and the optical loss spectrum for each type of pure water was measured by the detection device 23. The results are shown in Figure 5.

From Figure 5, it is clear that the hetero-core optical fiber sensor device 1 having a coating film 7 made of oleic acid exhibits an overall increase in light loss in an aqueous quinine solution compared to pure water, and furthermore, it is clear that the overall light loss increases as the concentration of quinine increases.

The heterocore section 3 of the heterocore optical fiber sensor device 1, which is provided with a coating film 7 made of dioctyl phosphate, was immersed in pure water and a 10 mM quinine aqueous solution, and white light in the wavelength range of 360-2000 nm was introduced from the light source 22 into the optical transmission section 2, and the optical loss spectrum for each type of pure water was measured by the detector 23. The results are shown in Figure 6.

From Figure 6, it is clear that the hetero-core optical fiber sensor device 1 equipped with a coating film 7 made of dioctyl phosphate exhibits an overall increase in optical loss in the quinine aqueous solution compared to pure water.

Next, FIG. 7 shows the results of detection of the optical loss of 11 types of aqueous solutions containing quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein at a concentration of 10 millimolar, relative to pure water, superimposed on the results of detection by a heterocore optical fiber sensor device 1 having a coating film 7 made of oleic acid and the heterocore optical fiber sensor device 1 having a coating film 7 made of dioctyl phosphate.

From Figure 7, it is clear that even in aqueous solutions of the same compound, the heterocore optical fiber sensor device 1 with a coating film 7 made of oleic acid and the heterocore optical fiber sensor device 1 with a coating film 7 made of dioctyl phosphate have different optical loss values relative to pure water, and that by combining the detection results of the heterocore optical fiber sensor device 1 with a coating film 7 made of oleic acid and the detection results of the heterocore optical fiber sensor device 1 with a coating film 7 made of dioctyl phosphate, a specific compound can be more reliably identified.

1...Heterocore optical fiber sensor device, 2...Light transmission section 2, 3...Heterocore section, 4...Optical fiber, 5a, 5b...Core, 6a, 6b...Cladding, 7...Peritoneal membrane, 21...Detection section, 22...Light source 22, 23...Detection device, 24...Analysis device.

Claims (2)

A hetero-core optical fiber sensor device comprising an optical fiber, the hetero-core portion having a core and a clad, the core of the hetero-core portion having a core and a clad respectively connected to the core and the clad of the optical transmission portion, the core of the hetero-core portion having a smaller diameter than the core of the optical transmission portion,
A coating membrane made of a negatively charged lipid is provided on the outer peripheral surface of the clad of the heterocore portion,
When a compound acting on negatively charged lipids selected from the group consisting of quinine, cinchonidine, hydroquinidine, strychnine, gramine, papaverine, norlaudanosine, caffeine, theophylline, thiamine, and daidzein is present in the external environment surrounding the coating film, the refractive index of the coating film changes due to the action of the compound acting on the negatively charged lipids, and light transmitted through the core of the light transmission section leaks into the cladding in the heterocore section, and the compound acting on the negatively charged lipids is detected by measuring the light loss spectrum due to the change in intensity of the leaked light reflected by the coating film whose refractive index has been changed . The heterocore optical fiber sensor device according to claim 1, wherein the negatively charged lipid is oleic acid or dioctyl phosphate.

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