JP2007178188A - Liquid detecting optical waveguide type sensor and optical waveguide type liquid detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid detecting optical waveguide type sensor which is not large-scaled and used for detecting the leak of blood because a part of a blood sending needle falls off in artificial dialysis and the leak accident of blood occurs. <P>SOLUTION: The liquid detecting optical waveguide type sensor is constituted so that one side of the flat plate-shaped flexible optical waveguide 4 formed on a flexible substrate 1 is formed as an optical fiber connection part, a reflecting film 5 is formed to the other end of the flexible optical waveguide 4 and the surface of the core 2 on the side separated from the substrate is exposed. The optical waveguide type liquid detector has a liquid detector main body 10 constituted of a light emitting means 11, an intensity measuring means 12 for measuring the intensity of the detected light and the directional bonding means 14 arranged between those means and an input and output optical fiber 13 and the optical waveguide type sensor is connected to the input and output optical fiber 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid detection type optical waveguide sensor and an optical waveguide type liquid detection device.

  For example, in artificial dialysis, a blood leak sensor is installed to detect that blood has leaked into the dialysate due to a pinhole or the like generated in the semipermeable membrane of the dialyzer. For example, Patent Document 1 discloses that light having two peak wavelengths with different absorption rates for blood is emitted separately from the light emitting element, transmitted through the dialysate and received by the light receiving element, and light having two wavelengths with respect to the dialysate. A blood leakage detector that detects a blood leakage state in a dialysate by comparing voltage levels obtained by converting the permeation amount of the blood is described. A blood leakage detector that detects leakage of blood into the dialysate using a light emitting element and a light receiving element is also described in Patent Document 2.

  In artificial dialysis, a part of the blood-feeding needle may fall out, causing blood to leak from the hole provided on the side of the needle and causing an accident. It is desirable to install a sensor for detection.

  As a technique related to the detection of such a blood leak, there is a chemical liquid leakage detection technique for supplying and injecting a chemical liquid under pressure from a chemical liquid injector to a needle pierced from a human skin into a blood vessel.

  For example, in Patent Document 3, a plurality of electrodes are provided on a patch configured to be adhered to a skin portion where a needle is stabbed with an adhesive, and a change in impedance of a human tissue between these electrodes is detected to leak a chemical solution. An apparatus for detecting is described.

On the other hand, as a prior art, flat flexible optical waveguides composed of a clad and a core are described in Patent Documents 4 and 5 and the like.
JP-A-4-357961 JP-A-6-327766 US Pat. No. 5,964,703 JP 2001-154050 A JP 2001-116941 A

The above prior art has the following problems.
1. Since the blood leakage detection technique of Patent Document 1 or Patent Document 2 detects blood leakage based on the amount of light transmitted between the light emitting element and the light receiving element, blood leakage from the portion of the skin pierced with the needle It is difficult to apply to the detection. That is, in this blood leakage detection technique, a space is required between the light emitting element and the light receiving element, where light is transmitted unobstructed and the leaked blood blocks the light. However, even if such a space is formed, the light-emitting element and the light-receiving element must be attached to the part of the skin where the needle is stabbed.
2. In addition, the blood leakage detection technique disclosed in Patent Document 3 makes it easy for a person to feel uncomfortable when an electric current is passed through the skin even though it is very small.
In order to solve the above-mentioned problems, the present invention has an object to construct a liquid detection optical waveguide sensor by rationally applying a flat flexible optical waveguide.

  In the present invention, in order to solve the above-described problems, one side of the flat flexible optical waveguide formed on the flexible substrate is configured as an optical fiber connection portion, a reflective film is formed on the other side, and further away from the substrate. We propose an optical waveguide sensor for liquid detection that is configured by exposing the core surface on the other side.

  According to the present invention, in the above configuration, it is proposed that the core is formed in a tapered shape that becomes wider from one side to the other side of the optical waveguide.

  In the present invention, the liquid detection device main body is constituted by the light emitting means, the intensity measuring means of the received light, and the directional coupling means arranged between these means and the input / output optical fiber, and the input / output optical fiber An optical waveguide type liquid detection device configured by connecting the optical waveguide type sensor to the above is proposed.

  In the present invention, it is proposed that the directional coupling means is constituted by the fiber coupler 14 in the above apparatus.

  In the optical waveguide sensor of the present invention, the surface of the optical waveguide whose core surface is exposed corresponds to the skin side, is positioned and fixed in the vicinity of the needle pierced on the skin, and is connected to the optical waveguide sensor. The fiber is used by being connected to the input / output optical fiber of the liquid detection device main body by an optical connector.

  In the above use state, when there is no blood leakage from the needle, the light propagating from the liquid detection device body through the input / output optical fiber to the core of the optical waveguide of the optical waveguide sensor is reflected on the exposed surface of the core. Due to the difference in refractive index with air in contact with the exposed surface (for example, the refractive index of the core: 1.46, the refractive index of air: 1.0), it reflects with the corresponding reflectance and returns to the liquid detector main body, and the intensity of the reflected light is Measured.

  In this state, when the blood leaks from the needle stuck in the skin and comes into contact with the exposed core, the refractive index of blood is higher than that of air, for example, the refractive index of water occupying 90% of the plasma component is 1.3. The reflectance of light on the exposed surface of the core is lowered, and thus the intensity of reflected light that is reflected by the exposure of the core and measured by the liquid detection device main body is lowered. Therefore, leakage of blood from the needle can be detected by the decrease in the intensity of the reflected light.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an embodiment of an optical waveguide liquid detection device using an optical waveguide sensor according to the present invention. FIG. 2 is an enlarged view of a portion of the optical waveguide sensor in FIG. 2 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 4 shows components for connecting the optical waveguide sensor to the liquid detection device main body.
Reference numeral 1 denotes a flexible substrate. A flat flexible optical waveguide 4 composed of a core 2 and a clad 3 is formed on the substrate 1, and the surface of the core 2 on the side away from the substrate is exposed. . One side of the optical waveguide 4 is configured as an optical fiber connecting portion, and the core 2 is formed in a taper shape that is wide from one side to the other side of the optical waveguide 4, and a reflective film is formed on the other side of the optical waveguide 4. 5 is formed. The flat flexible optical waveguide 4 having such a configuration can be easily configured using conventional techniques such as Patent Documents 4 and 5 described above.

  Reference numeral 6 denotes an optical fiber connecting member connected to one side of the optical waveguide 4, and this optical fiber connecting member 6 has a groove-shaped engagement support portion 7, and the optical waveguide is provided in the engagement support portion 7. 4 is configured to engage and hold an end edge on one side. In order to ensure the holding of the optical waveguide 4, a stopper recess 8 is formed on one surface of the optical waveguide 4, and this stopper is provided inside the engagement support portion 7 of the optical fiber connection member 6. A stopper projection (not shown) that is elastically engaged with the recess 8 is provided, and this stopper projection can be retracted from the stopper recess 8 by an operating member (not shown) to be disengaged. ing. An optical fiber 9 is connected to the optical fiber connecting member 6, and a mechanism (not shown) for optically connecting the end face of the optical fiber 9 and the optical waveguide 4 is provided.

  Next, reference numeral 10 denotes a liquid detection device main body. The liquid detection device main body 10 includes a light emitting means 11 such as a laser diode, a received light intensity measuring means 12 including a photodiode as an element, an input / output optical fiber 13, A fiber coupler 14 as a directional coupling means is a main component. The fiber coupler 14 has a branching ratio of 1: 1. Reference numeral 15a denotes an optical connector connected to the input / output optical fiber 13, and an optical connector 15b connected to the optical fiber 9 on the optical waveguide sensor side is connected to the optical connector 15a.

  In the above configuration, in use, as shown in FIG. 5, the surface of the optical waveguide 4 where the surface of the core 2 is exposed corresponds to the skin side and is positioned in the vicinity of the needle 17 pierced in the blood vessel 16. The optical fiber 9 fixed and connected to the optical fiber connecting member 6 is connected to the input / output optical fiber 13 of the liquid detection device main body 10 by the optical connectors 15a and 15b.

  In the above use state, when there is no blood leakage from the needle 17, the light propagating from the liquid detection device body 10 through the input / output optical fiber 13 to the core 2 of the optical waveguide 4 of the optical waveguide sensor is the core. 2 is reflected by the corresponding reflectance due to the difference in refractive index (for example, the refractive index of the core: 1.46, the refractive index of air: 1.0) with the air in contact with the exposed surface, and returns to the liquid detection device main body 10. The intensity of the reflected light is measured.

Here, although different from the optical waveguide in the present invention, the reflectance R at which the light propagating through the core 2 of the optical fiber is reflected at the end face and the received light intensity PR of the reflected light in the received light intensity measuring means 12 are expressed by the following equations. Indicated by
Reflectance R = {(n _g −n ₀ ) ² / (n _g + n ₀ ) ² } × 100 (%)
Received light intensity P _R = {(P _0/2 ) × R / 100} / 2
Where n _{g is} the refractive index of the core of the optical fiber, n _{0 is} the refractive index of the medium in contact with the end face of the core, and P ₀ is the intensity of light transmitted from the light emitting means.

So as the medium on the end face of the core 2 of the optical waveguide sensors, air, water and the refractive index is brought into contact with three liquid which is matched to the refractive index of the core of the optical fiber, reflectance R and the light-receiving intensity P _R The result of measuring the received light intensity while obtaining the theoretical value is as shown in the table below. However, the measurement of the received light intensity is carried out for two types, one obtained by polishing the end face of the optical fiber and one obtained by cutting the cleaver, and the light intensity P ₀ transmitted from the light emitting means 11 is 1135 μW. The refractive index of the core is 1.46.

Refractive index Reflectance Received light intensity Measured value (μW)
n ₀ R (%) P _R (μW) End face polishing Cleaver cutting Air 1.0 3.50 9.92 9.05 8.45
Water 1.3 0.34 0.95 0.63 0.59
Matching liquid 1.45 0.001 0.003 0.02 0.01

  From the above theoretical calculation and measurement results, when the medium in contact with the end face of the core of the optical fiber is air and water, the intensity of the reflected light measured by the received light intensity measuring means differs by one digit or more. It can be seen that these can be identified.

  Therefore, in the optical waveguide sensor of the present invention, it can be easily analogized that the reflectance changes due to the change in the refractive index of the medium in contact with the exposed surface of the core 2.

  Accordingly, when blood leaks from the needle 17 pierced in the skin in the above-described use state and comes into contact with the exposed surface of the core 2, the refractive index of blood is higher than that of air, for example, the refractive index of water occupying 90% of plasma components. Is about 1.3 as shown in the above table, the light reflectivity at the exposed surface of the core 2 is reduced, and thus the intensity of the reflected light reflected by the exposed surface of the core and measured by the liquid detection device main body 10. Decreases. Since this decrease in strength is relatively large, it is possible to reliably detect the presence of moisture, that is, the presence of blood, and thus to reliably detect blood leakage from the needle 17.

  In this embodiment, since the core 2 is formed in a taper shape that is wide from one side to the other side of the optical waveguide 4, the core 2 has a large area in contact with a medium such as blood. Can be detected. Further, since the core 2 is tapered so as to be wide, reflection of light due to the wide core 2 can be suppressed.

  However, in other embodiments, the core 2 can be shaped with a constant width.

  In the above-described use of the optical waveguide sensor of the present invention, as shown in FIG. 5, blood is absorbed between the surface of the optical waveguide 4 where the surface of the core 2 is exposed and the skin, such as absorbent cotton. If the fiber assembly 18 that diffuses is interposed, the blood leaked from the needle 17 can be diffused along the surface of the optical waveguide 4, and the above-described detection can be performed reliably. Reference numeral 20 in the drawing denotes a covering member such as absorbent cotton that covers the optical waveguide sensor and the needle 17.

  As described above, the optical waveguide sensor of the present invention and the liquid detection device using the same are applied to a device for detecting blood leakage from a needle in dialysis or the like, but the optical waveguide sensor of the present invention and the same are used. The liquid detection device used can be used for detection of water and other liquids in other applications.

  The optical waveguide sensor of the present invention is hygienic because it can be removed from the optical fiber connecting member 6 and discarded after it is used for detection of blood leakage as described above.

Since the optical waveguide sensor and the liquid detection device using the same according to the present invention are as described above, they have the following characteristics and have great industrial applicability.
1. Since the optical waveguide sensor utilizes light reflection on the exposed surface of the core, it does not require a pair of a light emitting element and a light receiving element, and therefore does not become large and can be easily attached to a human arm or the like. be able to.
2. Since no current is passed through the skin, the user does not feel uncomfortable.
3. Moreover, since the optical waveguide sensor of the present invention can be constructed at a very low cost, it is not economically burdened even if it is discarded after being used only once.

It is explanatory drawing which shows embodiment of the optical waveguide type liquid detection apparatus using the optical waveguide type sensor which concerns on this invention. FIG. 2 is an enlarged view of a portion of the optical waveguide sensor in FIG. 1. It is the sectional view on the AA line of FIG. It is a perspective view which shows the component which connects an optical waveguide type sensor to a liquid detection apparatus main body. It is typical sectional drawing of the use condition of the optical waveguide type sensor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flexible substrate 2 Core 3 Clad 4 Flat flexible optical waveguide 5 Reflective film 6 Optical fiber connection member 7 Engagement support part 8 Stopper recessed part 9 Optical fiber 10 Liquid detection apparatus main body 11 Light emission means 12 Light reception intensity measurement means 13 Input / output light Fiber 14 Fiber coupler 15a, 15b Optical connector 16 Blood vessel 17 Needle 18 Hole 19 Fiber assembly 20 Cover member

Claims (4)

That one side of the flat flexible optical waveguide formed on the flexible substrate is configured as an optical fiber connection portion, a reflection film is formed on the other side, and the core surface on the side away from the substrate is further exposed. An optical waveguide sensor for liquid detection. 2. The optical waveguide sensor for liquid detection according to claim 1, wherein the core is formed in a taper shape that is wide from one side to the other side of the optical waveguide. A liquid detection device main body is constituted by the light emitting means, the received light intensity measuring means, and the directional coupling means arranged between these means and the input / output optical fiber, and the input / output optical fiber is defined in claim 1 or An optical waveguide type liquid detection device comprising the optical waveguide type sensor according to any one of 2 connected. 4. The optical waveguide liquid detection device according to claim 3, wherein the directional coupling means is constituted by a fiber coupler.

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