WO2018169202A1 - Optical waveguide sensor and concentration measuring system using same - Google Patents

Abstract

An optical waveguide sensor and a concentration measuring system using the same are provided. An optical waveguide sensor according to an embodiment of the present invention comprises: an optical waveguide for obtaining first light from one side thereof connected to a light source and transmitting second light to the other side thereof; an inner sheath formed outside the optical waveguide; and a measurement unit formed by partially removing the inner sheath to expose a part of the optical waveguide to the outside, wherein the optical waveguide comes into contact with a material, the concentration of which is to be measured, through the measurement unit.

Description

Optical waveguide sensor and concentration measurement system using the same

The present invention relates to an optical waveguide sensor and a concentration measuring system using the same, and more particularly, to a sensor capable of detecting a concentration of a specific material using the optical waveguide and a concentration measuring system using the same.

In general, a sensor using an optical waveguide, represented by an optical fiber, uses various variables such as the intensity of light passing through the optical waveguide, the refractive index and the length of the optical waveguide, the mode, and the change in the polarization state. Various information such as pressure can be measured. Optical waveguide sensors have the advantage of being able to measure ultra-precise wideband, are not affected by electromagnetic waves, and are easy to measure remotely. In addition, since the measurement unit does not use electricity and has excellent corrosion resistance of the silica material, there is an advantage that there are almost no restrictions on the use environment.

On the other hand, a general chemical sensor or biosensor for concentration measurement includes an electrode in order to use the electrical properties of the measurement material. In this case, since electricity must be transmitted from an electrode, and a conductor such as an electric wire is required to transmit the electrical signal measured by the measuring unit to an external measuring instrument, there is a problem in the use environment.

In order to solve the problems of the prior art as described above, an embodiment of the present invention is capable of real-time diagnosis, simple and compact production, and at the same time an optical waveguide sensor having a high sensitivity and a concentration measuring system using the same. To provide.

According to an aspect of the present invention for solving the above problems, there is provided an optical waveguide sensor. The optical waveguide sensor may include an optical waveguide configured to acquire a first light from one side connected to a light source and to transmit a second light to the other side; An endothelial formed on the outside of the optical waveguide; And a measuring part formed by removing a part of the endothelium so that a part of the optical waveguide is exposed to the outside, wherein the optical waveguide is in contact with the measuring material to measure the concentration through the measuring part.

The optical waveguide may be provided such that the other side thereof is connected to an optical output meter for measuring the output of the second light.

The light source may be a helium-neon laser.

The concentration of the measurement material may be measured using the intensities of the first light and the second light represented by the following equation.

Where T is the light output ratio, P _{in is} the intensity of the first light, P _{out is} the intensity of the second light, and T ₀ is the light output ratio when the concentration is 0, loss (dB) is the amount of light loss due to the numerical aperture difference. NA _B : numerical aperture of measurement part, NA _C : numerical aperture of optical waveguide sensor outside measurement part, n _core : refractive index of optical waveguide,

: Refractive index of endothelial, n _{(liquid cladding)} : Refractive index of measuring material, L: Length of measuring part, α: Loss function according to measuring material concentration C (α = α ₀ + α ₁ C + α ₂ C ² ), C≤ 0.1%)

The measurement material is an aqueous solution of glycerol, and when the intensity of the first light is 3200mW, the concentration of the measurement material may be expressed by the following equation.

Where C is the sample concentration

According to an aspect of the present invention, a concentration measuring system using an optical waveguide sensor is provided. A density measuring system using the optical waveguide sensor, the light source for generating a first light of a certain intensity; An optical waveguide sensor receiving the first light from the light source and converting the first light into a second light by using a measurement material; And a detection device receiving the second light from the optical waveguide sensor and detecting a concentration of the measurement material.

The light source may be a helium-neon laser.

The sensor may include an optical waveguide configured to receive a first light from one side connected to the light source and to transmit the second light to the detection device; An endothelial formed on the outside of the optical waveguide; And a measuring part formed to be in contact with the measurement material by removing a part of the endothelium so that a part of the optical waveguide is exposed to the outside.

The concentration of the measurement material may be measured using the intensities of the first light and the second light represented by the following equation.

Where T is the light output ratio, P _{in is} the intensity of the first light, P _{out is} the intensity of the second light, and T ₀ is the light output ratio when the concentration is 0, loss (dB) is the amount of light loss due to the numerical aperture difference. NA _B : numerical aperture of measurement part, NA _C : numerical aperture of optical waveguide sensor outside measurement part, n _core : refractive index of optical waveguide,

: Refractive index of endothelial, n _{(liquid cladding)} : Refractive index of measuring material, L: Length of measuring part, α: Loss function according to measuring material concentration C (α = α ₀ + α ₁ C + α ₂ C ² ), C≤ 0.1%)

The measurement material is an aqueous solution of glycerol, and when the intensity of the first light is 3200mW, the concentration of the measurement material may be expressed by the following equation.

Where C is the sample concentration

The optical waveguide sensor and the concentration measuring system using the same according to an embodiment of the present invention have the effect of measuring the concentration of the measurement material in real time.

In addition, the optical waveguide sensor and the concentration measurement system using the same according to an embodiment of the present invention, while being able to be manufactured in a small size has the effect of measuring the concentration of the measurement material with high sensitivity.

In addition, the optical waveguide sensor and the concentration measuring system using the same according to an embodiment of the present invention, since the electrode is not used to measure the concentration of the measurement material has the effect that can be applied to various environments by lowering the constraints of the use environment have.

In addition, the optical waveguide sensor and the concentration measurement system using the same according to an embodiment of the present invention, by using a change in the aberration inside the optical waveguide due to the contact of the measurement material has the effect of reducing the constraint of the use environment.

1 is a view showing an optical waveguide sensor according to an embodiment of the present invention.

2 is a view showing a measuring unit of the optical waveguide sensor according to an embodiment of the present invention.

3 is a view showing a concentration measurement system using an optical waveguide sensor according to an embodiment of the present invention.

4 is a schematic diagram illustrating an optical waveguide sensor according to an exemplary embodiment of the present invention.

5 is a graph showing a simulation result for comparing the light output ratio according to the measuring unit length of the optical waveguide sensor according to an embodiment of the present invention.

6 is a graph showing a simulation result of measuring light output when the length of the measuring unit of the optical waveguide sensor according to an embodiment of the present invention is 5cm.

7 is a graph comparing a simulation result and a theory of an optical waveguide sensor according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like elements throughout the specification.

1 is a view showing an optical waveguide sensor according to an embodiment of the present invention, Figure 2 is a view showing a measuring unit of the optical waveguide sensor according to an embodiment of the present invention.

Referring to FIG. 1, an optical waveguide sensor 100 according to an exemplary embodiment of the present invention includes an optical waveguide 110, an endothelial 120, and an outer skin 130. In this case, the optical waveguide sensor 100 includes an endothelial 120 on the outside of the optical waveguide 110, and an outer skin 130 for protecting the optical waveguide 110 and the endothelial 120. It may be further provided with. In this case, the optical waveguide 110 may be formed of, for example, silica, and the endothelial 120 may be formed of a polymer type, and the refractive index of the optical waveguide 110 may be greater than that of the endothelial 120. have.

On the other hand, referring to Figure 2, the optical waveguide sensor 100 according to an embodiment of the present invention, the measuring unit 150 is formed. The measuring unit 150 contacts the sample and measures the concentration of the substance to be measured included in the sample. To this end, the measurement unit 150 is formed by exposing a part of the optical fiber 110 by removing a part of the outer skin 130 and the endothelial 120 of the optical waveguide sensor 100.

In other words, the measurement unit 150 is a portion in which the optical waveguide 110 is exposed to the outside, and the optical waveguide 110 contacts the sample to induce the refraction of light by performing the role of the endothelial 120. have. At this time, the measuring unit 150 may be preferably formed in a length of 5cm, the present invention is not limited to this and may be formed in a predetermined length.

In addition, although FIG. 1 and FIG. 2 show that there is a part of the endothelial 120 without the outer skin 130 at both ends of the measuring unit 150 of the optical waveguide sensor 100 according to the present invention, It is shown to explain easily the connection relationship between the envelope, the endothelial and the optical waveguide of the waveguide sensor, a preferred example of the present invention is that the endothelial is exposed to the outside alone.

On the other hand, Figure 3 shows a concentration measuring system using an optical waveguide sensor according to an embodiment of the present invention.

Referring to FIG. 3, the concentration measurement system 200 using the optical waveguide sensor according to an embodiment of the present invention includes a light source 210, a fiber coupler 230, an optical waveguide sensor 100, a collimator 250, and the like. Meter 270 is included.

The light source 210 generates a first light therein and transmits the first light to the fiber coupler 230. At this time, the output of the first light generated by the light source 210 is adjustable according to the user's setting, it is preferable that the visible light. This is because the amount of light in the visible light region is hardly absorbed by the aqueous solution. Therefore, the light source 210 may be a device for generating and emitting visible light such as a laser diode and an LED, and in any one embodiment of the present invention, the light source 210 may be a helium-neon laser (He-Ne laser).

Fiber coupler 230 is used when there is more than one input or output in an optical waveguide system. For example, the fiber coupler 230 receives the first light generated by the light source 210 and transmits the same amount of light separately to the optical waveguide sensor 100 and another optical waveguide (not shown), thereby intensifying the two lights. It may be provided to compare the differences directly. In addition, in the concentration measurement system 200 using the optical waveguide sensor according to an embodiment of the present invention, the fiber coupler 230 may be omitted according to the user's setting.

The optical waveguide sensor 100 receives the first light from the fiber coupler 230 or the light source 210 and converts the first light into the second light using a sample contacting the measuring unit 150. The optical waveguide sensor 100 receives the first light through one end and contacts the sample through the measuring unit 150. Accordingly, the first light passing through the optical waveguide sensor 100 decreases in transmission efficiency due to the difference in refractive index between the endothelium 120 and the sample, and changes to a second light whose intensity is changed to the outside through the other end. Delivered.

The collimator 250 converts the advancing direction of the second light into a constant direction. The second light passes through the optical waveguide sensor 100 using reflection at the interface between the optical waveguide 110 and the endothelial 120 or the sample. Therefore, the second light transmitted to the other end of the optical waveguide sensor 100 has various propagation directions, so that the collimator 250 receives the second light and converts the second light to travel in a predetermined direction to prevent the loss. It is provided.

The measuring device 270 receives the second light and measures its intensity. The measuring device 270 receives the second light converted to proceed in a predetermined direction through the collimator 250 and measures the intensity of the obtained second light. In addition, the measuring device 270 may compare the intensity of the first light and the second light using the intensity of the first light set and output from the light source 210, and the comparison result may be expressed as Equation 1 below. have.

Where T is the ratio of transmitted light output, P _{in is} intensity of first light, and P _{out is} intensity of second light.

In this case, the intensity of the second light varies depending on the concentration of the substance contained in the sample. This is because the refractive index of the sample also changes when the concentration of the substance contained in the sample changes.

On the other hand, Figure 4 is a schematic diagram showing an optical waveguide sensor according to an embodiment of the present invention. Referring to FIG. 4, an optical waveguide sensor according to an exemplary embodiment may be divided into an A zone through which the first light flows, a B zone through which the measurement unit exists, and a C zone through which the second light flows. In this case, the numerical aperture in each zone may be represented by Equation 2 below, and the numerical aperture NA is a numerical value representing the light condensing ability.

Where NA = numerical aperture, n ₁ : refractive index of optical fiber, n ₂ : refractive index of endothelial)

Using Equation 2, the A and C regions of FIG. 4 have the same numerical aperture, and the B region, which is the measuring unit, has an n ₂ value different from the n ₂ values of the A and C regions because the endothelial is replaced by a sample. To have.

On the other hand, in the general optical waveguide, the refractive index of the endothelial is 0.2 to 1% lower than the refractive index of the optical waveguide so that the total reflection of the light passing through the optical waveguide, the refractive index of the optical waveguide is formed to be about 1.46 to 1.47. The endothelium is formed to have a refractive index of 1.44 to 1.46.

Therefore, ₂ n A value of the zone and the C zone is formed to be larger than the refractive index of the zone B n ₂ value of the air. In the optical waveguide sensor 100 according to the exemplary embodiment of the present invention, the overall intensity does not decrease in the process of transmitting the first light to the measuring unit 150, but the numerical aperture change in the measuring unit 150 is changed. Due to the second light is formed and is transmitted to the C zone, the loss of some light occurs, this light loss can be determined by the numerical aperture ratio represented by the following equation (3).

(Where NA _B : numerical aperture in zone B, NA _C : numerical aperture in zone C)

At this time, when a sample having a certain concentration is bonded to the B zone, the value of n ₂ is formed larger than air, so that light loss may be reduced in the process of transmitting light from the B zone to the C zone.

On the other hand, the amount of light loss due to the difference in numerical aperture can also be expressed by the following equation (4).

Where P _{in is} the intensity of the first light and P _{out is} the intensity of the second light.

Therefore, summarizing the equations (1) to (4), the transmitted light output ratio T may be modified to the following equation (5), where the transmitted light output ratio T may have a correction factor according to the concentration.

(T ₀ : light output ratio when concentration is 0, L: length of measurement part, α: loss function according to sample concentration C (α = α ₀ + α ₁ C + α ₂ C ² ))

That is, summarizing the above-described Equations 1 to 5, the optical waveguide sensor 100 according to an embodiment of the present invention, the aberration difference due to the liquid endothelial replaced by the sample in the zone B, through which the optical waveguide The light loss is generated in the light passing through the sensor 100, and thus the aberration-changing optical waveguide may be configured to measure the concentration of the liquid substance to be detected by measuring the changed light intensity.

Meanwhile, simulation results for proving Equation 5 according to an embodiment of the present invention are shown in FIG. 5. 5 is a diagram illustrating a simulation result for comparing the light output ratio according to the length of the measuring unit of the optical waveguide sensor according to an embodiment of the present invention. The simulation according to an embodiment of the present invention was performed by dividing the measurement unit into the length of (A) 5cm and (B) 1cm, and the aqueous solution of glycerol in which the refractive index information for each concentration is well known as a test sample. The size of the first light generated in the light source was kept constant at 3200 mW. In this case, the results for each experiment are shown in Table 1 below.

density(%)	Power intensity (mW)		density(%)	Power intensity (mW)
	(A)	(B)		(A)	(B)
0	2924.89	2480.00	0.1	3097.36	2560.00
0.001	2935.72	2516.67	0.3	3098.64	2566.67
0.003	2939.28	2500.00	0.5	3092.70	2550.00
0.005	2949.16	2510.00	One	3053.29	2550.00
0.007	2950.45	2506.67	3	3060.67	2546.67
0.009	2966.71	2516.67	5	3043.90	2536.67
0.01	2985.76	2506.67	7	3029.81	2523.33
0.02	2999.24	2506.67	10	3022.34	2513.33
0.03	3012.24	2506.67	15	3008.05	2506.67
0.04	3007.42	2536.67	20	3011.62	2493.33
0.05	3014.28	2526.67	25	3007.77	2483.33
			30	2990.52	2483.33

Graphs for the data shown in Table 1 are shown in FIGS. 5A and 5B, respectively. Looking at Table 1 and the graph, the result of measuring the intensity of light passing through the measuring unit, that is, the intensity of the second light is the case where the length of the measuring unit 150 is 5cm (A), the length of the measuring unit 150 is 1cm ( It was measured larger than B). In addition, in both experiments, the intensity of the second light increased until the glycerol concentration reached 0.3%, and it was confirmed that the intensity of the second light decreased while exceeding 0.3%.

6 shows a simulation result graph of measuring light output when the length of the measuring unit of the optical waveguide sensor according to the exemplary embodiment of the present invention is 5 cm. When the measurement unit 150 of the optical waveguide sensor according to an embodiment of the present invention is 5cm, the repeated measurement result of measuring the intensity of the second light according to the glycerol concentration by fixing the intensity of the first light to 3200mW is shown in Table 2 below. It is displayed.

density(%)	Power intensity (mW)	density(%)	Power intensity (mW)
0	2383.39	0.05	2942.19
0.001	2458.50	0.1	2950.81
0.002	2490.65	0.3	2922.44
0.003	2557.25	0.5	2851.17
0.004	2572.34	0.7	2778.97
0.005	2589.91	0.9	2733.67
0.006	2587.91	One	2688.98
0.007	2600.34	3	2656.39
0.008	2625.68	5	2610.47
0.009	2650.72	10	2590.57
0.01	2749.88	15	2582.67
0.02	2771.71	20	2581.90
0.03	2820.03	25	2590.57
0.04	2845.36	33	2562.89

Referring to the graphs of Table 2 and Figure 6, the simulation results according to an embodiment of the present invention, when the concentration of the aqueous solution of glycerol is less than 0.1%, the higher the concentration was shown that the output intensity of the second light increases When it exceeds 0.1%, it decreases gradually, and when it exceeds 5%, the output decreases significantly.

Therefore, in the present invention, when the glycerol concentration is 0.1% or less, the sample is brought into contact with the measuring unit 150 and the first light is emitted to measure the intensity of the second light, and the intensity of the glycerol contained in the sample is compared by comparing the intensities of the two lights. Can be inverted, and the result of the inversion is shown in Table 3 below.

T = (2 light / 1 light)	density(%)	T = (2 light / 1 light)	density(%)
0.7448	0	0.9194	0.05
0.7683	0.001	0.9221	0.1
0.7783	0.002	0.9133	0.3
0.7991	0.003	0.8910	0.5
0.8039	0.004	0.8684	0.7
0.8093	0.005	0.8543	0.9
0.8088	0.006	0.8403	One
0.8126	0.007	0.8301	3
0.8205	0.008	0.8158	5
0.8284	0.009	0.8096	10
0.8593	0.01	0.8071	15
0.8662	0.02	0.8068	20
0.8813	0.03	0.8096	25
0.8892	0.04	0.8009	30

On the other hand, Figure 7 is a graph comparing the experimental results of Table 3 and the T value of the equation (5). Referring to FIG. 7, the T value of Equation 5 is represented by a solid line when the size of the first light is 3200 mW, and the experimental results of Table 3 are represented by dots.

The two results show similar shapes and values up to a maximum concentration of 2%, but the ratio of the first light and the second light expressed in the light transmittance (T) has two concentrations. Referring to the graph, the concentration of glycerol is 0.1%. It is desirable to limit the glycerol concentration to 0.1% in order to increase the accuracy of the sensor since the light transmittance continues to increase until it reaches.

Therefore, in the optical waveguide sensor and the concentration measurement system using the same according to an embodiment of the present invention, when the glycerol concentration is limited to 0.1% or less and the intensity of the first light is kept constant at 3200 mW, the first light is measured. Using the ratio of the second light and the glycerol concentration of the sample can be measured using the following equation (6).

Equation 6

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments set forth herein, and those skilled in the art who understand the spirit of the present invention, within the scope of the same idea, the addition of components Other embodiments may be easily proposed by changing, deleting, adding, and the like, but this will also fall within the spirit of the present invention.

Claims (10)

1. An optical waveguide for obtaining a first light from one side connected to the light source and transferring a second light to the other side;

   An endothelial formed on the outside of the optical waveguide; And

   And a measuring unit formed by removing a portion of the endothelium so that a portion of the optical waveguide is exposed to the outside.

   The optical waveguide, the optical waveguide sensor in contact with the measurement material to measure the concentration through the measuring unit.
2. The method of claim 1,

   The optical waveguide, the optical waveguide sensor is provided so that the other side is connected to the optical output meter for measuring the output of the second light.
3. The method of claim 2,

   The light source is an optical waveguide sensor is a helium-neon laser.
4. The method of claim 1,

   The concentration of the measurement material is an optical waveguide sensor measured using the intensity of the first light and the second light represented by the following equation.

   

   

   Where T is the light output ratio, P _{in is} the intensity of the first light, P _{out is} the intensity of the second light, and T ₀ is the light output ratio when the concentration is 0, loss (dB) is the amount of light loss due to the numerical aperture difference. NA _B : numerical aperture of measurement part, NA _C : numerical aperture of optical waveguide sensor outside measurement part, n _core : refractive index of optical waveguide,

   

   : Refractive index of endothelial, n _{(liquid cladding)} : Refractive index of measuring material, L: Length of measuring part, α: Loss function according to measuring material concentration C (α = α ₀ + α ₁ C + α ₂ C ² ), C≤ 0.1%)
5. The method of claim 4, wherein

   The measuring substance is an aqueous solution of glycerol, and when the intensity of the first light is 3200mW, the concentration of the measuring substance is expressed by the following equation.

   

   Where C is the sample concentration
6. A light source generating a first light of a constant intensity;

   An optical waveguide sensor receiving the first light from the light source and converting the first light into a second light by using a measurement material; And

   And a detection device receiving the second light from the optical waveguide sensor and detecting a concentration of the measurement material.
7. The method of claim 6,

   The light source is a concentration measurement system using an optical waveguide sensor that is a helium-neon laser.
8. The method of claim 6,

   The optical waveguide sensor,

   An optical waveguide receiving a first light from one side connected to the light source and transmitting the second light to the detection device;

   An endothelial formed on the outside of the optical waveguide; And

   And a measuring unit which is formed to be in contact with the measurement material by removing a portion of the endothelium so that a portion of the optical waveguide is exposed to the outside.
9. The method of claim 6,

   The concentration of the measurement material, the density measurement system using an optical waveguide sensor is measured using the intensity of the first light and the second light represented by the following equation.

   

   

   Where T is the light output ratio, P _{in is} the intensity of the first light, P _{out is} the intensity of the second light, and T ₀ is the light output ratio when the concentration is 0, loss (dB) is the amount of light loss due to the numerical aperture difference. NA _B : numerical aperture of measurement part, NA _C : numerical aperture of optical waveguide sensor outside measurement part, n _core : refractive index of optical waveguide,

   

   : Refractive index of endothelial, n _{(liquid cladding)} : Refractive index of measuring material, L: Length of measuring part, α: Loss function according to measuring material concentration C (α = α ₀ + α ₁ C + α ₂ C ² ), C≤ 0.1%)
10. The method of claim 9,

    The measurement material is an aqueous solution of glycerol, the concentration measurement system using an optical waveguide sensor in which the concentration of the measurement material is expressed by the following equation when the intensity of the first light is 3200mW.

    

    Where C is the sample concentration

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