JP2017138135A - Device and method for detecting substance to be detected - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device and a detection method having high detection accuracy.SOLUTION: A problem in improvement of detection accuracy can be solved by using detection substance which interacts with substance to be detected to absorb light of a specific wavelength and the light of the specific wavelength absorbed by the detection substance which interacts with the substance to be detected.SELECTED DRAWING: None

Description

  The present invention relates to an apparatus and a method for detecting a substance to be detected.

  Detection of specific substances is required in various fields. For example, in-vehicle air cleaners in the automotive field, hydrogen sensors for fuel cells, alcohol checkers in the checker field, bad breath checkers, harmful gas alarms in the alarm field, etc. It needs to be detected.

  In the medical field, it is known that certain substances are associated with certain diseases. For example, ammonia and hepatic encephalopathy, acetone and insulin deficiency, hydrogen and lactose intolerance, mercaptan and bad breath are known.

  Therefore, various devices for detecting specific substances have been reported. Patent Document 1 discloses a detection probe in which a compound containing a porphyrin metal complex is supported on a metal thin film. The detection probe of Patent Document 1 uses a surface plasmon resonance phenomenon to detect a low molecular chemical substance (for example, carbon monoxide, cyanide gas, trichlorethylene, etc.).

  Patent Document 2 discloses a substance measuring device including an optical fiber having a sensor area with a core exposed. The substance measuring apparatus of Patent Document 2 uses a measurement target substance that absorbs laser light (that is, evanescent light) that has propagated through an optical fiber and leaked from a sensor area, and attenuates the laser light. Measure the substance.

  Patent Document 3 discloses a sensor in which an optical waveguide layer and an adsorbed substance detection thin film are provided on a crystal resonator. The sensor of Cited Document 3 detects a substance to be detected by utilizing the fact that the thin film for detecting an adsorbed substance adsorbs the substance to be detected and changes the absorption rate of evanescent light.

  Patent Document 4 discloses an optical waveguide sensor including a tube body that introduces and discharges a substance to be detected, an optical waveguide formed on the inner surface of the tube body, and a detection material formed on the optical waveguide. The optical waveguide sensor of the cited document 4 detects a substance to be detected by utilizing that a detection material reacts with a substance to be detected, absorbs evanescent light, and attenuates laser light propagating through the optical waveguide.

JP-A-11-194131 JP2013-72730A International Publication No. 2006/038367 Pamphlet JP 2010-203838 A

As described above, an apparatus using absorption of evanescent light to detect a substance has been reported. Although the light emitted from the light source of such an apparatus has a wide range of wavelengths, the range of wavelengths of light absorbed as evanescent light is narrow. Therefore, when measurement is performed using light of a wide range of wavelengths, there is a problem that the change in light intensity caused by absorption of evanescent light is diluted and detection accuracy is lowered.
Therefore, an object of the present invention is to provide a detection device and a detection method having high detection accuracy.

  As a result of intensive studies by the present inventors in view of the above object, it is possible to suppress the change in the light intensity caused by the absorption of evanescent light from being diluted by using light of a specific wavelength, and as a result, detection It was found that the accuracy can be improved.

Therefore, the present invention includes the following embodiments.
[1] An apparatus for detecting a substance to be detected,
An optical waveguide comprising a core and a sensing substance disposed on the surface of the core and interacting with the substance to be sensed to absorb light of a specific wavelength;
A light source that is provided at one end of the optical waveguide and that allows light of a specific wavelength to be absorbed by the detection substance that interacts with the detection target substance; and the specific light that is provided at the other end of the optical waveguide and emitted from the optical waveguide. A photodetector that selectively detects light of a wavelength;
Including the device.
[2] The apparatus according to [1], wherein the substance to be detected is ammonia gas, and the substance to be detected includes tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof.
[3] The device according to [2], wherein the detection substance further includes gold nanoparticles or zinc oxide nanoparticles.
[4] The device according to any one of [1] to [3], wherein the light source is a light emitting diode and the photodetector is a photodiode.

[5] A method for detecting a substance to be detected,
In the absence of a substance to be detected, light of a wide range of wavelengths is applied to an optical waveguide that includes a core and a detection substance that is disposed on the surface of the core and that interacts with the substance to be detected and absorbs light of a specific wavelength. Measure the light with a wide range of wavelengths incident and exit from the optical waveguide with a spectrometer to obtain a wavelength spectrum;
In the presence of a substance to be detected, light in a wide range of wavelengths is incident on the optical waveguide, the light having a wide range of wavelengths emitted from the optical waveguide is measured with a spectrometer, and a wavelength spectrum is obtained; and Compare the wavelength spectrum obtained in the absence of UV light with the wavelength spectrum obtained in the presence of the substance to be detected, determine the wavelength with different light intensity, and select the light source that emits the light of the determined specific wavelength To do,
A light source selection step including: a light having a specific wavelength incident on the optical waveguide from the light source selected in the light source selection step, and the light intensity of the specific wavelength emitted from the optical waveguide is determined by the specific wavelength. A detection step of detecting a substance to be detected by detecting with a photodetector that selectively detects the light of
Including the method.
[6] The method according to [5], wherein the detecting step includes detecting the presence and concentration of the substance to be detected.
[7] The method according to [5] or [6], wherein the light source is a light-emitting diode and the photodetector is a photodiode.

  According to the present invention, a substance to be detected can be detected with high accuracy.

FIG. 1-1 shows the result of detecting light emitted from an optical waveguide with a spectroscope using a deuterium + halogen lamp in the absence of ammonia gas. FIG. 1-2 shows the result of detecting light emitted from the optical waveguide with a spectrometer using a deuterium + halogen lamp in the presence of 2 ppm ammonia gas. FIG. 1-3 shows the result of detecting the light emitted from the optical waveguide with a spectrometer using a deuterium + halogen lamp in the presence of 5 ppm ammonia gas. FIG. 1-4 shows the result of detecting the light emitted from the optical waveguide with a spectrometer using a deuterium + halogen lamp in the presence of 7 ppm of ammonia gas. FIG. 1-5 shows the result of detecting the light emitted from the optical waveguide with a spectrometer using a deuterium + halogen lamp in the presence of 10 ppm ammonia gas. FIG. 2 shows a result of detecting light emitted from the optical waveguide with a spectroscope using a green LED. FIG. 3 shows the result of detecting light emitted from the optical waveguide with a spectroscope using a red LED. FIG. 4 shows the experimental procedure of Example 5. FIG. 5 shows the result of detection by converting light emitted from the optical waveguide into a voltage using a purple LED. FIG. 6 shows the result of detection by converting light emitted from the optical waveguide into voltage using a green LED. FIG. 7 shows the result of detection by converting light emitted from the optical waveguide into voltage using a red LED. FIG. 8-1 shows the absorbance when TPPS hydrate + gold nanoparticles are used. FIG. 8-2 shows the absorbance when TPPS hydrate alone is used. FIG. 8-3 shows the absorbance when gold nanoparticles alone are used. FIG. 9-1 shows the absorbance when TPPS hydrate + zinc oxide nanoparticles are used. FIG. 9-2 shows the absorbance when TPPS hydrate alone is used. FIG. 9-3 shows the absorbance when zinc oxide nanoparticles alone are used.

The present invention relates to a detection substance that interacts with a substance to be detected and absorbs light of a specific wavelength, and a specific wavelength that is absorbed by a detection substance that interacts with the substance to be detected (hereinafter also referred to as “interaction detection substance”). Including an embodiment using the light. In the present embodiment, the interaction detection substance absorbs the evanescent light leaking from the optical waveguide, thereby causing a change in the light intensity and detecting the detection target substance based on the change. Depending on the degree of change in light intensity, the concentration of the substance to be detected can also be detected. In this embodiment, since light of a specific wavelength is used, dilution of the change in light intensity can be suppressed as compared with the case where light of a wide range of wavelengths is used. As a result, the substance to be detected can be detected with high accuracy.
Hereinafter, the detection apparatus and detection method of the present invention will be described.

<Detection device>
One embodiment of the present invention relates to a detection apparatus for a substance to be detected, including an optical waveguide, a light source, and a photodetector.

  The target substance to be detected in the present invention is not particularly limited. For example, a gas substance can be mentioned as a to-be-detected substance. More specifically, ammonia, acetone, hydrogen, methane, mercaptan, ethanol, argon, carbon dioxide, carbon monoxide, formaldehyde, volatile organic compounds (VOC), hydrogen sulfide, ozone, and the like can be given.

  The optical waveguide of the detection device includes a core and a detection substance disposed on the surface of the core. The sensing substance can be disposed on all or part of the surface of the core.

  The optical waveguide may further include a clad disposed on the surface of the core. By making the refractive index of the cladding lower than the refractive index of the core, light can be propagated in the core by total reflection. When the optical waveguide includes a clad, it is preferable not to arrange the clad between the core and the detection substance. Thereby, the evanescent light can be increased and the change in the light intensity caused by the absorption of the evanescent light can be increased. Moreover, it is preferable not to arrange | position a clad so that a detection substance may be covered. Thereby, interaction of a detection substance and a to-be-detected substance is securable.

  The optical waveguide may further include a protective coating disposed on the surface of the core and / or the clad. By including the protective film, the optical waveguide can be protected from damage (for example, physical damage, chemical damage, etc.). When the optical waveguide includes a protective film, it is preferable not to arrange the protective film between the core and the detection substance. Thereby, the evanescent light can be increased and the change in the light intensity caused by the absorption of the evanescent light can be increased. Moreover, it is preferable not to arrange | position a protective film so that a detection substance may be covered. Thereby, interaction of a detection substance and a to-be-detected substance is securable.

  The optical waveguide can have various shapes. For example, examples of the shape of the optical waveguide include a planar shape and a fiber shape. More specifically, examples of the shape of the optical waveguide include a slab shape, a mesa shape, a ridge shape, an embedded shape, and a semi-embedded shape.

  The core included in the optical waveguide is not necessarily composed of a special component, and can be composed of a component similar to the core component of a known optical waveguide. For example, as a component of the core, quartz, multicomponent glass, acrylic resin and the like can be cited.

  The clad included in the optical waveguide does not necessarily need to be configured with a special component, and can be configured with a component similar to a known optical waveguide cladding component. Examples of the clad component include quartz, multi-component glass, silicone resin, fluorine-containing polymer, and the like.

  The protective coating contained in the optical waveguide is not necessarily composed of a special component, and can be composed of the same components as those of the known protective coating of the optical waveguide. For example, as a component of the protective film, polyimide, nylon, fluororesin, and the like can be given.

又はその水和物等を挙げることができる。 The detection substance contained in the optical waveguide is a substance that interacts with the substance to be detected and absorbs light of a specific wavelength. The substance to be detected varies depending on the type of substance to be detected. For example, when the substance to be detected is ammonia gas, examples of the substance to be detected include porphyrin compounds. In this case, more specifically, tetraphenylporphyrin tetrasulfonic acid (TPPS):

Or the hydrate etc. can be mentioned.

  The detection substance is disposed on the exposed surface portion of the core (that is, the surface portion on which the clad, the protective coating, etc. are not disposed). The detection substance may be directly arranged on the surface of the core, or may be indirectly arranged on the surface of the core via a fixing agent that fixes the detection substance to the surface of the core.

等を挙げることができる。 The fixative varies depending on the type of detection substance. For example, when the detection substance is a porphyrin compound (for example, tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof), poly (diallyldimethylammonium chloride) (PDDA):

Etc.

  When the substance to be detected is ammonia gas, the substance to be detected preferably contains metal nanoparticles in addition to a porphyrin compound (for example, tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof). For example, examples of metal nanoparticles include gold nanoparticles and zinc oxide nanoparticles. By using the metal nanoparticles in combination, the absorption rate of light of a specific wavelength by the interaction detection substance can be improved. For example, when the substance to be detected is ammonia gas, and the substance to be detected includes tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof, and gold nanoparticles or zinc oxide nanoparticles, etc. The absorptance of light having wavelengths of 510 nm and about 680 to 730 nm can be improved. This is because electrons move from metal nanoparticles to TPPS, the structure of TPPS changes, and J-association is promoted, so that the absorption peak near the J-aggregate-derived absorption peak (409 nm, 706 nm) increases significantly. Presumed to be.

  The light source of the detection device is provided at one end of the optical waveguide. The light source emits light of a specific wavelength and makes the light enter the optical waveguide. The light emitted from the light source has a specific wavelength that is absorbed by the interaction sensing material. For example, a porphyrin compound that interacts with ammonia gas (for example, tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof) absorbs light having wavelengths near 407 nm, 500 nm, and 705 nm.

  The light of a specific wavelength emitted from the light source can be selected from, for example, purple light, blue light, green light, yellow light, orange light, and red light. Although it is difficult to clearly define the boundaries of the wavelength range of these lights, approximately violet light has a wavelength in the range of about 380 to 440 nm and blue light has a wavelength in the range of about 440 to 480 nm. Green light has a wavelength in the range of about 480-570 nm, yellow light has a wavelength in the range of about 570-590 nm, orange light has a wavelength in the range of about 590-620 nm, and red light has It has a wavelength in the range of about 620-780 nm.

  The light source is not particularly limited as long as it can emit light of a specific wavelength. For example, as a light source, a light emitting diode (LED) can be used. More specifically, examples of the light source include a purple light emitting diode, a blue light emitting diode, a green light emitting diode, a yellow light emitting diode, an orange light emitting diode, and a red light emitting diode. When the interaction detection material absorbs light of a plurality of wavelengths, a plurality of corresponding light emitting diodes may be used.

  The photodetector of the detection device is provided at the other end of the optical waveguide. The photodetector selectively detects light having a specific wavelength emitted from the light source and emitted from the optical waveguide. The photodetector varies depending on the type of light. For example, a photodiode (PD) etc. can be mentioned as a photodetector. When a plurality of light emitting diodes are used as the light source, a plurality of corresponding photodiodes may be used.

  When a light emitting diode is used as a light source, it is not necessary to use a spectroscope as a photodetector, and a photodiode can be used instead. Thereby, an inexpensive and highly accurate detection apparatus can be provided.

  By including a light source that emits light of a specific wavelength, the detection device can suppress a change in light intensity caused by absorption of evanescent light from being diluted. As a result, the substance to be detected can be detected with high accuracy. In addition, even when the substance to be detected is mixed with many other substances, the detection device includes a light source that emits light of a specific wavelength, so that the substance to be detected can be selectively detected. .

<Detection method>
One embodiment of the present invention relates to a method for detecting a substance to be detected, including a light source selection step and a detection step. Matters already described in the item <Detecting device> are appropriately omitted in the description of the present embodiment.

  The light source selection step includes a first step to a third step. In the first step, light in a wide range of wavelengths is incident on the optical waveguide in the absence of the substance to be detected, and the light in the wide range of wavelengths emitted from the optical waveguide is measured with a spectrometer to obtain a wavelength spectrum. Including. The second step includes causing light of a wide range of wavelengths to enter the optical waveguide in the presence of the substance to be detected, measuring the light of the wide range of wavelengths emitted from the optical waveguide with a spectrometer, and obtaining a wavelength spectrum. . The second step may be performed a plurality of times while changing the concentration of the substance to be detected. Any of the first step and the second step may be performed first.

  The light in a wide range of wavelengths used in the first step and the second step may be anything that is expected to include light of a specific wavelength that is absorbed by the interaction detection substance. For example, light in a wide wavelength range can include light in the visible region (about 380 to 780 nm). Further, for example, the light having a wide range of wavelengths may include a combination of at least two lights selected from the group consisting of violet light, blue light, green light, yellow light, orange light, and red light. In addition, what is necessary is just to select another light again, when the selected light does not contain the light of the specific wavelength which an interaction detection substance absorbs.

The optical waveguides used in the first step and the second step are as described above in the section <Detection device>.
The spectrometer used in the first step and the second step is not necessarily a special spectrometer, and a known spectrometer can be used.

  In the third step of the light source selection step, the wavelength spectrum obtained in the first step and the wavelength spectrum obtained in the second step are compared, a wavelength having a different light intensity is determined, and the determined specific wavelength is determined. Including selecting a light source that emits light. The selected light source emits light of a specific wavelength that is absorbed by the interaction detection substance. The light source is preferably selected from light emitting diodes, more specifically, purple light emitting diodes, blue light emitting diodes, green light emitting diodes, yellow light emitting diodes, orange light emitting diodes and red light emitting diodes. When there are a plurality of lights having a specific wavelength determined in the third step, a plurality of corresponding light emitting diodes may be selected.

  In the detection step, light of a specific wavelength is incident on the optical waveguide from the light source selected in the light source selection step, and the light intensity of the specific wavelength emitted from the optical waveguide is selected. Detecting the target substance by detecting with an optical detector that automatically detects. In the detection step, the presence of the substance to be detected can be detected based on the change in the light intensity. The detection step can detect the concentration of the substance to be detected based on the degree of change in the light intensity. In the detection step, the light emitted from the optical waveguide may be converted into other information (for example, current, voltage, etc.), and the presence and concentration of the substance to be detected may be detected based on the converted information.

  A photodiode is preferably used as the photodetector. When a plurality of light emitting diodes are selected in the light source selection step, a plurality of corresponding photodiodes may be used.

  In the detection method, by selecting a light source that emits light of a specific wavelength in the light source selection step, it is possible to suppress a change in light intensity caused by absorption of evanescent light from being diluted. As a result, the substance to be detected can be detected with high accuracy. In addition, even if the substance to be detected is mixed with many other substances, the substance to be detected can be selectively detected by selecting a light source that emits light of a specific wavelength in the light source selection step. Can do.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited to this.

[Example 1]
An optical fiber (FIBER-600-VIS, manufactured by Ocean Optics) having a core, a clad, and a polyimide coating was prepared. The optical fiber was immersed in a mixed solution of sulfuric acid and hydrogen peroxide for 1 hour to remove the polyimide coating. Next, the optical fiber was immersed in 5% hydrofluoric acid for 10 hours, the clad was removed, and the core was exposed.
The exposed optical fiber was immersed in 5 mg / ml poly (diallyldimethylammonium chloride) (PDDA) for 5 minutes to form a fixative film. Next, the optical fiber was immersed in 1 mM tetraphenylporphyrin tetrasulfonic acid (TPPS) hydrate for 5 minutes to form a sensing substance film on the fixing agent film, thereby manufacturing an optical waveguide.

[Example 2]
A deuterium + halogen lamp was installed at one end of the optical waveguide manufactured in Example 1, and a spectrometer was installed at the other end of the optical waveguide. In the absence and presence of ammonia gas, light from a deuterium + halogen lamp was incident on the optical waveguide, and the light emitted from the optical waveguide was detected by a spectrometer. The results are shown in FIGS. 1-1 to 1-5. Absorbance changes were observed at wavelengths near 407 nm, 500 nm, and 705 nm.

[Example 3]
Of the light having a wavelength in which the change in absorbance was confirmed in Example 2, green light was selected. A green LED was installed at one end of the optical waveguide manufactured in Example 1, and a spectroscope was installed at the other end of the optical waveguide. In the absence and presence of ammonia gas, light was emitted from the green LED into the optical waveguide, and the light emitted from the optical waveguide was detected by a spectrometer. The results are shown in FIG. It was confirmed that the change in absorbance increases as the concentration of ammonia gas increases.

[Example 4]
Of the light having a wavelength for which a change in absorbance was confirmed in Example 2, red light was selected. An experiment similar to that of Example 3 was performed except that a red LED was used instead of the green LED. The results are shown in FIG. It was confirmed that the change in absorbance increases as the concentration of ammonia gas increases.

[Example 5]
Of the light having a wavelength in which a change in absorbance was confirmed in Example 2, purple light was selected. A purple LED was installed at one end of the optical waveguide manufactured in Example 1, and a PIN photodiode (PD) was installed at the other end of the optical waveguide. An amplifier was connected to the PIN photodiode.
Ammonia gas was introduced by the experimental procedure shown in FIG. 4, the light emitted from the optical waveguide was converted into a voltage, and the change in voltage was measured. The results are shown in FIG. It was confirmed that the change in voltage increased as the concentration of ammonia gas increased. Also, as shown in the experimental procedure of FIG. 4, when the supply and stop of ammonia gas are repeated intermittently, as shown in the lower diagram of FIG. 5, the voltage rises quickly when ammonia gas is supplied, and the voltage drops when stopped. Thus, it can be seen that there is high responsiveness and reproducibility.

[Example 6]
Of the light having a wavelength in which the change in absorbance was confirmed in Example 2, green light was selected. The same experiment as in Example 5 was performed except that a green LED was used instead of the purple LED. The results are shown in FIG. It was confirmed that the voltage changes depending on the presence or absence of ammonia gas. However, the behavior of the green light was different from that of the purple light of Example 5 and the red light of Example 7 below, and the voltage change due to the ammonia concentration was small. As shown in FIG. 2, the wavelength of the green LED is in the range of 480 to 510 nm, the absorbance signal decreases at 490 nm, and the absorbance signal increases at 507 nm, so the total signal detected by the photodiode. Thus, it is presumed that the difference in signal intensity due to the change in ammonia concentration did not appear well. In this case, if an optical wavelength filter is used to measure at a narrow wavelength such as 485 to 495 nm or 500 to 510 nm, the change in voltage is expected to increase as the ammonia gas concentration increases.

[Example 7]
Of the light having a wavelength for which a change in absorbance was confirmed in Example 2, red light was selected. The same experiment as in Example 5 was performed except that a red LED was used instead of the purple LED. The results are shown in FIG. It was confirmed that the change in voltage increased as the concentration of ammonia gas increased.

[Example 8]
Gold nanoparticles were produced by a solution plasma method in which plasma was generated between a pair of gold electrodes in a solution to generate gold nanoparticles. The optical fiber with the core exposed in the same manner as in Example 1 was dipped in a gold nanoparticle dispersion for 30 minutes and dried, then dipped in a TPPS solution for 5 minutes and dried to produce an optical waveguide. Using this optical waveguide, the absorbance of ammonia gas was compared with the absorbance when TPPS hydrate was used alone and the absorbance when gold nanoparticles were used alone. The results are shown in FIGS. 8-1 to 8-3. When TPPS hydrate and gold nanoparticles were used in combination, the absorbance was significantly improved as compared with the film of TPPS alone, and in particular, the absorbance of light having wavelengths of about 470 to 510 nm and about 680 to 730 nm was improved.

[Example 9]
Zinc oxide (ZnO) nanoparticles were produced by a solution plasma method in which plasma was generated between a pair of zinc (Zn) electrodes in a solution (for example, pure water) to generate and oxidize zinc nanoparticles. The optical fiber with the core exposed in the same manner as in Example 1 was dipped in a zinc oxide nanoparticle dispersion for 30 minutes and dried, then dipped in a TPPS solution for 5 minutes and dried to produce an optical waveguide. Using this optical waveguide, the absorbance of ammonia gas was compared with the absorbance when TPPS hydrate was used alone and the absorbance when zinc oxide nanoparticles were used alone. The results are shown in FIGS. 9-1 to 9-3. When TPPS hydrate and zinc oxide nanoparticles were used in combination, the absorptance of light having wavelengths of about 470 to 510 nm and about 680 to 730 nm was improved.

Claims (7)

An apparatus for detecting a substance to be detected,
An optical waveguide comprising a core and a sensing substance disposed on the surface of the core and interacting with the substance to be sensed to absorb light of a specific wavelength;
A light source that is provided at one end of the optical waveguide and that allows light of a specific wavelength to be absorbed by the detection substance that interacts with the detection target substance; and the specific light that is provided at the other end of the optical waveguide and emitted from the optical waveguide. A photodetector that selectively detects light of a wavelength;
Including the device.   The apparatus according to claim 1, wherein the substance to be detected is ammonia gas, and the substance to be detected includes tetraphenylporphyrin tetrasulfonic acid or a hydrate thereof.   The apparatus of claim 2, wherein the sensing material further comprises gold nanoparticles or zinc oxide nanoparticles.   The device according to claim 1, wherein the light source is a light emitting diode and the photodetector is a photodiode. A method for detecting a substance to be detected,
In the absence of a substance to be detected, light of a wide range of wavelengths is applied to an optical waveguide that includes a core and a detection substance that is disposed on the surface of the core and that interacts with the substance to be detected and absorbs light of a specific wavelength. Measure the light with a wide range of wavelengths incident and exit from the optical waveguide with a spectrometer to obtain a wavelength spectrum;
In the presence of a substance to be detected, light in a wide range of wavelengths is incident on the optical waveguide, the light having a wide range of wavelengths emitted from the optical waveguide is measured with a spectrometer, and a wavelength spectrum is obtained; and Compare the wavelength spectrum obtained in the absence of UV light with the wavelength spectrum obtained in the presence of the substance to be detected, determine the wavelength with different light intensity, and select the light source that emits the light of the determined specific wavelength To do,
A light source selection step including: a light having a specific wavelength incident on the optical waveguide from the light source selected in the light source selection step, and the light intensity of the specific wavelength emitted from the optical waveguide is determined by the specific wavelength. A detection step of detecting a substance to be detected by detecting with a photodetector that selectively detects the light of
Including the method.   The method according to claim 5, wherein the detecting step includes detecting the presence and concentration of the substance to be detected.   The method according to claim 5 or 6, wherein the light source is a light emitting diode and the photodetector is a photodiode.

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