JP2011013079A - Gas detection element and gas detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent gas from being unintendedly supplied to the surface of a color development layer, in a detection element equipped with a base material, constituting a light waveguide and the color development layer developing a color by reaction with a target substance.SOLUTION: The gas detecting element (30) is equipped with a first holding member (21), a second holding member (22) and a closure member (26), in addition to the base material (31) and the color development layer (32). A first holding member (21) is formed into a frame shape and laminated on the base material (31) so that the color development layer (32) so as to face the opening of the first holding member (21). A second holding member (22) is laminated on the base material (31) on the side opposite to the first holding member (21), to hold the base material (31) along with the first holding member (21). The closure member (26) is laminated on the first holding member (21), on the side opposite to the base material (31) so as to close the opening of the first holding member (21) and has an inflow passage (26a) for allowing a gas to flow into the gas chamber (20), surrounded by the first holding member, and an outflow passage (26b) for allowing the gas to flow out of the gas chamber (20) formed thereto.

Description

  The present invention relates to a gas detection element including a base material constituting an optical waveguide and a gas detection device including the gas detection element.

  Conventionally, a gas detection element including a base material constituting an optical waveguide is known. For example, Patent Literature 1 describes a gas detection device including this type of gas detection element.

  Specifically, the gas detection device of Patent Document 1 is a formaldehyde detection device including a detection element that constitutes a formaldehyde detector. The detection element of this gas detection device includes a flat base material constituting an optical waveguide and a mesoporous layer carrying a detection reagent that develops color by reaction with formaldehyde. The mesoporous layer is laminated on one side of the substrate. In this gas detection device, an evanescent wave is generated when the light incident on the optical waveguide is totally reflected on the surface of the substrate. For this reason, if the mesoporous layer is in a colored state, light of a predetermined wavelength is absorbed by the light reflecting surface on which the mesoporous layer is laminated, and the optical characteristics of the light emitted from the optical waveguide change. This gas detection device detects the concentration of formaldehyde using a change in the optical characteristics of light emitted from the optical waveguide.

JP 2008-82840 A

  By the way, in this kind of gas detection element, if the color developing layer is exposed to the outside, gas is unintentionally supplied to the surface of the color developing layer. For this reason, for example, when detecting the concentration of the target substance, the target gas whose concentration is to be detected is supplied to the surface of the coloring layer before the detection, so that the concentration of the target substance can be accurately detected. Disappear. For example, when a volatile detection reagent is used for the color developing layer, the detection reagent may volatilize and the function of the color developing layer may be impaired.

  The present invention has been made in view of the above point, and an object of the present invention is to provide a gas detection element including a base material constituting an optical waveguide and a color development layer that develops color by reaction with a target substance. The object is to prevent unintentional supply of gas to the surface.

  The first invention forms an optical waveguide (12) which is formed in a flat plate shape and has one end face of the opposite end face as the light incident face (31a) and the other light exit face (31b). The base material (31) is laminated on the light reflecting surface of the optical waveguide (12) among the surfaces of the base material (31), and a predetermined chemical substance contained in the gas is used as a target substance to react with the target substance. A gas detection element (30) provided with a coloring layer (32) that develops color is an object. And this gas detection element (30) is formed in the frame shape which has opening, is laminated | stacked on the said base material (31) so that the said color development layer (32) may face this opening, and the said opening is gas chamber (20 ) Constituting the first holding member (21) and the base material (31) on the side opposite to the first holding member (21) side, and the base material (21) together with the first holding member (21). 31) and a second holding member (22) that is laminated on the side opposite to the base (31) side of the first holding member (21) so as to close the opening of the first holding member (21). A closing member (26) formed with an inflow passage (26a) for allowing gas to flow into the gas chamber (20) and an outflow passage (26b) for allowing gas to flow out from the gas chamber (20); It has.

  In the first invention, the first holding member (21) and the closing member (26) are laminated on one side of the base material (31), and the second holding member (22) is provided on the other side of the base material (31). Are stacked. The base material (31) is held by the first holding member (21) and the second holding member (22). In addition, a gas chamber (20) in which the coloring layer (32) is exposed is formed on one side of the substrate (31) by the first holding member (21) and the closing member (26). Gas is taken in and out of the gas chamber (20) through the inflow passage (26a) and the outflow passage (26b). In the first aspect of the invention, the gas chamber (20) in which the color developing layer (32) is exposed is formed using the first holding member (21) that holds the base material (31).

  In a second aspect based on the first aspect, the periphery of the opening of the first holding member (21) is in contact with the surface of the base material (31) over the entire periphery.

  In the second invention, since the periphery of the opening of the first holding member (21) is in contact with the surface of the base material (31) over the entire periphery, the base material (31) and the first holding member (21) Gas does not flow into the gas chamber (20) from between the two, and no light enters the gas chamber (20) from between the base material (31) and the first holding member (21).

  According to a third invention, in the first or second invention, the first holding member (21) and the first holding member are formed in a frame shape having an opening, and the base (31) is accommodated in the opening. 2 is provided between the holding member (22) and has an optical path in a corresponding portion of the incident surface (31a) and the exit surface (31b) of the optical waveguide (12), and the entrance surface (31a) and the exit surface A frame-shaped closing member (23) for closing the end face of the base material (31) around (31b) is provided.

  In the third invention, the base material (31) is accommodated in the opening of the frame-shaped closing member (23). The end surface of the base material (31) faces the edge surface of the opening of the frame-shaped closing member (23). The end surfaces of the base material (31) around the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12) facing each other are closed by a frame-shaped blocking member (23).

  According to a fourth invention, in any one of the first to third inventions, the second holding member (22) is formed in a flat plate shape whose planar shape is larger than that of the base material (31). The second holding member (22) has an incident opening (22a) through which light incident on the incident surface (31a) of the optical waveguide (12) passes, and an output surface (31b) of the optical waveguide (12). An emission opening (22b) for allowing the emitted light to pass therethrough is formed.

  In 4th invention, the planar shape of a flat 2nd holding member (22) is larger than the planar shape of a base material (31). One side of the base material (31) is covered by the second holding member (22). The second holding member (22) has an entrance opening (22a) and an exit opening (22b). The light that has passed through the entrance aperture (22a) reaches the entrance surface (31a) of the optical waveguide (12). The light emitted from the emission surface (31b) of the optical waveguide (12) passes through the emission opening (22b). In the fourth aspect of the present invention, on the second holding member (22) side of the base material (31), the regions through which the light reaching the base material (31) can pass are the entrance opening (22a) and the exit opening (22b). ).

  According to a fifth invention, in any one of the first to third inventions, the second holding member (22) is formed in a frame shape having an opening, and the opening is incident on the optical waveguide (12). The base (31) of the second holding member (22) is formed so as to extend outward from the surface (31a) and the emission surface (31b), while closing the opening of the second holding member (22). Is laminated on the opposite side to the incident side (27a) for allowing light to enter the incident surface (31a) of the optical waveguide (12) and the outgoing surface (31b) of the optical waveguide (12). And an opening forming member (27) having an emission opening (27b) through which the light to be transmitted passes.

  In the fifth invention, the opening of the second holding member (22) extends outward from the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12). That is, the incident surface (31a) and the emission surface (31b) of the optical waveguide (12) are located inside the edge of the opening of the second holding member (22) in plan view. The opening of the second holding member (22) is closed by the opening forming member (27) in which the entrance opening (27a) and the exit opening (27b) are formed. Therefore, the light that has passed through the entrance opening (27a) reaches the entrance surface (31a) after passing through the opening of the second holding member (22), and the light exiting from the exit surface (31b) 2 After passing through the opening of the holding member (22), it passes through the exit opening (27b). In the fifth invention, on the second holding member (22) side of the base material (31), the region through which the light reaching the base material (31) can pass is the entrance opening (22a) and the exit opening (22b). ).

  According to a sixth invention, in any one of the first to fifth inventions, the sixth invention is configured by a transparent member so as to block the entrance opening (22a, 27a) and the exit opening (22b, 27b). An opening closing member (28) is provided.

  In the sixth invention, the entrance opening (22a, 27a) and the exit opening (22b, 27b) are closed by the transparent opening closing member (28). The opening closing member (28) allows the light to pass through the entrance opening (22a, 27a) and the exit opening (22b, 27b), while the entrance opening (22a, 27a) and the exit opening. The gas is prevented from passing through (22b, 27b).

  The seventh invention is the gas detection element (30) of any one of the first to sixth inventions, a light emitter (41) that emits light incident on the optical waveguide (12), and the optical waveguide (12 ) And a light receiving body (42) for outputting an optical signal representing the optical characteristics of the received light, and receiving the optical signal, and the concentration of the target substance based on the change in the optical signal Or it is a gas detection apparatus (10) provided with the signal processing means (17) which detects presence or absence.

  In the seventh invention, the light emitted from the light emitter (41) enters the optical waveguide (12) of the gas detection element (30) of any one of the first to sixth inventions. The light that has entered the optical waveguide (12) propagates repeatedly after being reflected and is emitted. The light receiver (42) that has received the light emitted from the optical waveguide (12) outputs an optical signal representing the optical characteristics of the received light. The signal processing means (17) that receives the optical signal detects the concentration or presence of the target substance based on the change in the optical signal.

  In the present invention, the gas chamber (20) from which the coloring layer (32) is exposed is formed by using the first holding member (21) that holds the base material (31). The periphery of the gas chamber (20) is partitioned by the first holding member (21) and the closing member (26). The coloring layer (32) in the gas chamber (20) is not exposed to the outside of the gas detection element (30). The gas chamber (20) can be formed by a simple operation of stacking the closing member (26) on the first holding member (21). Therefore, the gas detection element (30) capable of preventing unintentional gas supply to the surface of the color developing layer (32) can be manufactured relatively easily.

  In the present invention, since the gas chamber (20) is formed by laminating the closing member (26) on the frame-shaped first holding member (21), the gas is formed depending on the thickness of the first holding member (21). The height of the chamber (20) (the length of the base material (31) in the thickness direction) is determined. Here, the higher the height of the gas chamber (20), the larger the volume of the dead space such as the corner. For this reason, the higher the height of the gas chamber (20), the more gas remains in the gas chamber (20) after detection of the target substance, and the remaining gas is detected when the next target substance is detected. The effect on is increased. Therefore, the height of the gas chamber (20) is preferably as low as possible as long as the gas can flow. However, for example, when the gas chamber (20) is formed by covering the base material (31) with a member in which a recess is formed, it is difficult to process the recess with high accuracy, and the gas chamber (20 ) Is difficult to form with high accuracy. On the other hand, in the present invention, it is possible to reduce the height of the gas chamber (20) only by reducing the thickness of the first holding member (21). Therefore, it is possible to accurately form the gas chamber (20) having a small dead space volume and a low height.

  Moreover, in the said 2nd invention, gas does not flow in into a gas chamber (20) from between a base material (31) and a 1st holding member (21). Accordingly, it is possible to more reliably prevent the gas from being unintentionally supplied to the surface of the coloring layer (32).

  In the second aspect of the invention, light does not enter the gas chamber (20) from between the base material (31) and the first holding member (21). Here, when there is a gap between the base material (31) and the first holding member (21), light passing through the gap may stray into the gas chamber (20). The stray light that has strayed into the gas chamber (20) affects the intensity of light emitted from the optical waveguide (12) and may affect the detection result of the target substance. On the other hand, in the second aspect of the invention, light does not enter the gas chamber (20) from between the base material (31) and the first holding member (21). Therefore, it can suppress that the intensity | strength of the light radiate | emitted from an optical waveguide (12) changes with stray light.

  In the third aspect of the invention, the end surface of the base material (31) around the incident surface (31a) and the emission surface (31b) of the optical waveguide (12) facing each other is blocked by the frame-shaped blocking member (23). It is peeling. On the end face of the base material (31), the area where light can enter is limited to the minimum necessary by the frame-shaped closing member (23). For this reason, it can suppress that the light which is unrelated to the detection of a target substance permeates into an optical waveguide (12) from the end surface of a base material (31).

  In each of the fourth and fifth inventions, on the second holding member (22) side of the base material (31), the region through which the light reaching the base material (31) can pass is the entrance opening (22a, 27a) and the emission openings (22b, 27b). For this reason, it can suppress that the light which is unrelated to the detection of a target substance permeates into an optical waveguide (12) from the 2nd holding member (22) side of a base material (31).

  In the sixth aspect of the invention, the opening blocking member (28) prevents the gas from passing through the incident opening (22a, 27a) and the emission opening (22b, 27b). For this reason, it is possible to prevent the gas from entering the gas detection element (30) through the entrance openings (22a, 27a) and the exit openings (22b, 27b).

FIG. 1 is a schematic configuration diagram of a gas detection device in which a cross section in a longitudinal direction of a gas detection element in the present embodiment is represented. FIG. 2 is a perspective view of the gas detection element of the present embodiment. FIG. 3 is a cross-sectional view in the short direction of the gas detection element of the present embodiment. FIG. 4 is a cross-sectional view of the base material showing a light reflection state in the optical waveguide. FIG. 5 is a plan view of the members constituting the gas detection element of the present embodiment, (A) is a plan view of the gas introduction plate, (B) is a plan view of the first holding plate, (C ) Is a plan view of the substrate frame plate, (D) is a plan view of the second holding plate, (E) is a plan view of the slit plate, (F) is a plan view of the acrylic window, (G) is a plan view of the window frame plate, and (H) is a plan view of the window holding plate. FIG. 6 is a perspective view of the base material from which the coloring layer is omitted. FIG. 7 is a chart showing the change over time of the intensity of the optical signal. FIG. 8 is a flowchart showing the flow of the detection operation. FIG. 9 is a schematic configuration diagram of a gas detection device in which a cross section in the longitudinal direction of a gas detection element in Modification 1 of the present embodiment is shown. FIG. 10 is a plan view of members constituting the gas detection element in Modification 1 of the present embodiment, (A) is a plan view of the gas introduction plate, and (B) is a plan view of the first holding plate. Yes, (C) is a plan view of the substrate frame plate, (D) is a plan view of the slit plate, (E) is a plan view of the acrylic window, and (F) is a plan view of the window frame plate. (G) is a plan view of the window holding plate. FIG. 11 is a schematic configuration diagram of a gas detection device in which a cross section in a longitudinal direction of a gas detection element in Modification 2 of the present embodiment is shown. FIG. 12 is a cross-sectional view of the gas detection element according to a modification of the present embodiment, cut in the lateral direction at the end of the base material. FIG. 13 is a cross-sectional view of the gas detection element in a modification of the present embodiment cut in the short direction at the position of the through hole.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  This embodiment is a gas detection device (10) provided with a gas detection element (30) according to the present invention. This gas detection device (10) is a device for detecting the concentration of a target substance in the gas using a predetermined chemical substance contained in the gas as the target substance (for example, formaldehyde). The gas detection device (10) is configured to detect the concentration of the target substance in the gas based on the change in optical characteristics accompanying color development due to the reaction between the target substance and the detection reagent (recognition molecule).

  In addition, the gas detection apparatus (10) of the present embodiment uses, for example, paradichlorobenzene, toluene, xylene, styrene, acetaldehyde, methylbenzene, etc. as a target substance in addition to formaldehyde by changing the detection reagent depending on the target substance. Can do.

<Overall configuration of gas detector>
As shown in FIG. 1, the gas detection device (10) of this embodiment includes a casing (11), a gas detection element (30), a light emitter (41), a light receiver (42), a signal processing unit (17), And an input / output unit (18).

  The casing (11) is formed in a box shape. The casing (11) accommodates the gas detection element (30), the light emitter (41), the light receiver (42), the signal processing unit (17), and the input / output unit (18). Inside the casing (11), an attachment portion (not shown) to which the gas detection element (30) is detachably attached is provided. The casing (11) includes an air supply passage (14) for supplying a gas to be measured to a gas chamber (20), which will be described later, and an exhaust passage (15) for discharging the gas in the gas chamber (20). And are provided. The supply passage (14) and the exhaust passage (15) are constituted by piping. The exhaust passage (15) is provided with an air pump (16) that sucks the gas in the gas chamber (20).

  As shown in FIG. 2, the gas detection element (30) is formed by laminating a plurality of members, and is formed in a rectangular plate shape as a whole. As shown in FIGS. 1 and 3, the gas detection element (30) includes a flat substrate (31) constituting an optical waveguide (12) for confining and transmitting light, and one side of the substrate (31). And a color developing layer (32) laminated on the upper surface (in FIG. 1). Inside the gas detection element (30), there is formed a gas chamber (20) into which the gas to be measured is introduced so that the coloring layer (32) is exposed and brought into contact with the coloring layer (32). Here, the base material (31) and the coloring layer (32) of the gas detection element (30) will be described, and details of the gas detection element (30) will be described later.

  The base material (31) is formed of a colorless and transparent glass substrate. The base material (31) is made of a material that transmits light in a band (hereinafter referred to as “absorption band”) that is absorbed by color development caused by the reaction between the target substance and the detection reagent. The end surface of the base material (31) is blocked by a base material frame plate (23) described later, leaving the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12).

  The base material (31) is formed in a square shape. The length of one side of the substrate (31) is 24 mm. Moreover, the outer peripheral end surface of the base material (31) extends perpendicularly to the upper and lower surfaces. The thickness of the substrate (31) is 0.15 mm. In addition, the base material (31) should just be about 0.05-2 mm in thickness.

  The coloring layer (32) is laminated on the light reflecting surface of the optical waveguide (12) in the surface of the substrate (31). The coloring layer (32) develops color by reaction with the target substance. The coloring layer (32) is formed over the entire surface of one side of the base material (31).

  The coloring layer (32) is composed of a mesoporous silica thin film having a large number of pores having a diameter of several nm. A detection reagent is supported in the pores of the color developing layer (32). That is, the color developing layer (32) is constituted by a mesoporous layer carrying a detection reagent. The coloring layer (32) has a surface to be exposed to the gas to be measured and a back surface to the adhesion surface (measurement surface) of the base material (31). The coloring layer (32) is configured such that when the target substance in the air to be measured enters the pores from the exposed surface, the target substance and the detection reagent react with each other to develop a color.

  In the present embodiment, a detection reagent that develops color by reaction with formaldehyde is used. As the formaldehyde detection reagent, the substances shown in the following i) to v) (described in JP-A-2008-82840) can be used. In addition to those shown in i) to v) above, one selected from enaminone derivatives such as 2-amino-3-penten-2-one, It can be used as a detection reagent for formaldehyde. When a chemical substance different from formaldehyde is used as a target substance, a detection reagent that develops color by reaction with the target substance is used.

i) 4-aminopent-3-en-2-one
ii) 4-Amino-3-octen-2-one
iii) 5-aminohept-4-en-3-one
iv) 4-amino-4-phenyl-3-buten-2-one
v) 3-amino-1,3-diphenyl-2-propen-1-one (3-amino-1,3-diphenylprop-2-en-1-one)
The detection reagent produces lutidine by a chemical reaction with formaldehyde. And this product, lutidine, has the characteristic of exhibiting an absorption peak, and absorbs most of light in the vicinity of a wavelength of 405 nm.

  The color developing layer (32) is configured to transmit light in a band that is absorbed by color development due to the reaction between the target substance and the detection reagent. Further, the pores of the color developing layer (32) are set to have an average diameter of 1/10 or less of the wavelength of light in the band absorbed by the color developed by the reaction between the target substance and the detection reagent. . In addition, the coloring layer (32) is configured to have a thickness corresponding to light in a band that is absorbed by the coloring caused by the reaction between the target substance and the detection reagent. For example, the coloring layer (32) has a thickness of 0. It is set to 01-2 μm.

  The light emitter (41) is formed of a laser diode or a light emitting diode. The light emitter (41) is disposed to face the incident surface (31a) of the optical waveguide (12). The light emitter (41) emits light to be incident on the optical waveguide (12). The incident angle θ of the light emitted from the light emitter (41) with respect to the incident surface (31a) is set so that an evanescent wave is generated at the interface between the base material (31) and the coloring layer (32). For example, when the refractive index n of the substrate (31) is 1.5, the incident angle θ is set to 61 °. In this case, the propagation angle is 55 °.

  The light emitted by the illuminant (41) includes light having a wavelength in a band that is absorbed by color development due to the reaction between the target substance and the detection reagent. Specifically, the light emitted from the light emitter (41) is light having a wavelength of around 405 nm. That is, when the reaction product of formaldehyde and the detection reagent is lutidine, the wavelength of light in the absorption band is 405 nm, and the light emitted by the illuminant (41) includes light absorbed by color development. Is set to

  The photoreceptor (42) is composed of a photodiode. The said photoreceptor (42) is arrange | positioned facing the output surface (31b) of an optical waveguide (12). The light receiver (42) is configured to receive light emitted from the optical waveguide (12) and output an optical signal representing the optical characteristics of the received light. The gas detection device (10) is configured such that the light received by the light emitter (41) is not directly received by the light receiver (42).

  The signal processing unit (17) constitutes a signal processing means (17) that detects the concentration of the target substance based on a change in the optical signal. Based on the intensity of the optical signal, the signal processing unit (17) detects a change in optical characteristics accompanying the color development of the coloring layer (32), that is, a decrease in the intensity of light of a predetermined wavelength, and based on this decrease, the target substance It is comprised so that the density | concentration of may be detected.

  Specifically, the signal processing unit (17) is configured to execute a first operation for detecting the concentration of the target substance by the rate method and a second operation for detecting the concentration of the target substance by the endpoint method. Yes. In the signal processing unit (17), a determination threshold value is set in advance for determining whether the concentration of the target substance is detected by the first operation or the second operation. The determination threshold is set using a calibration curve based on the rate method and a calibration curve based on the end point method. The threshold for determination is equal to the intensity of the optical signal after saturation in the calibration curve when the intensity of the optical signal is saturated in a predetermined time (for example, 3 minutes).

  The input / output unit (18) constitutes display means for displaying the concentration of the target substance, and also constitutes operation means for performing operations such as measurement ON and OFF. The input / output unit (18) is configured to receive the detection signal from the signal processing unit (17) and digitally display the absolute value of the concentration of the target substance.

  With the above configuration, when the light emitter (41) emits light, as shown in FIG. 4, in the optical waveguide (12), light incident from one of the opposite end faces propagates by repeating total reflection, and the other light is transmitted. Emits from the end face. If the coloring layer (32) is colored by reaction with the target substance, the light propagating through the optical waveguide (12) oozes out to the coloring layer (32) at the totally reflecting interface, and light of a predetermined wavelength. Is absorbed. As a result, the optical characteristics of the light emitted from the optical waveguide (12) change.

<Configuration of gas detection element>
As shown in FIG. 1, the gas detection element (30) includes a first holding plate (21), a second holding plate (22), and a base in addition to the base material (31) and the coloring layer (32). A material frame plate (23), a window frame plate (24), a window holding plate (25), a gas introduction plate (26), a slit plate (27), and an acrylic window (28) are provided. All of these eight members (21-28) have a rectangular outer peripheral shape. As shown in FIG. 5, six members (21, 22, 23, 24, 25, 27) excluding the gas introduction plate (26) and the acrylic window (28) among these eight members (21-28) Are laminated so that the outer circumferences have the same size and the outer circumferences coincide in plan view. Of these eight members (21-28), two screw holes (48) are formed in seven members (21-27) excluding the acrylic window (28). In the gas detection element (30), these seven members (21-27) are fastened by fixing screws that are screwed into the screw holes (48). Further, these seven members (21-27) are constituted by a black member (a member having a reflectance of about 1%) having a low light reflectance.

  In the present embodiment, the first holding plate (21) constitutes the first holding member (21). The second holding plate (22) constitutes the second holding member (22). The base frame plate (23) constitutes the frame-shaped closing member (23). The gas introduction plate (26) constitutes the closing member (26). The slit plate (27) constitutes the opening forming member (27). The acrylic window (28) constitutes the opening closing member (28).

  As shown in FIGS. 1, 3 and 5, in the gas detection element (30), the base material (31) is provided between the first holding plate (21) and the second holding plate (22). The substrate frame plate (23) is housed in the opening (23a). The end surface of the base material (31) is blocked by the base material frame plate (23), leaving the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12). In the base material (31), the base material frame plate (23) constitutes an optical waveguide (12) through which light propagates in the longitudinal direction (left-right direction in FIG. 1) of the gas detection element (30).

  The base material (31) is sandwiched between the first holding plate (21) and the second holding plate (22). The first holding plate (21) and the second holding plate (22) constitute holding means (21, 22) for holding the base material (31). Here, in the base material (31), as shown in FIGS. 3 and 6, there is a portion constituting the optical waveguide (12) in the central portion (35). The holding means (21, 22) holds the base material (31) at the base material side portions (36, 37) on both sides of the base material (31) and on the side of the optical waveguide (12). The holding means (21, 22) is not in contact with the optical waveguide (12).

  As shown in FIG. 5B, the first holding plate (21) is formed in a rectangular frame shape. The opening (21a) of the first holding plate (21) is formed in a substantially rectangular shape, and its corner is arcuate. The opening (21a) of the first holding plate (21) has a length in the longitudinal direction that is longer than the length of one side of the base material (31) (the length of the optical waveguide (12) in the light propagation direction). The length in the hand direction is shorter than the length of one side of the substrate (31) (the length in the width direction of the optical waveguide (12)). The first holding plate (21) is laminated on the first surface of the substrate (31) so that the coloring layer (32) faces the opening (21a). The first holding plate (21) holds the base material side portions (36, 37) from the first surface side of the base material (31).

  In the first holding plate (21), the portions facing each other across the opening (21a) in the width direction of the optical waveguide (12) constitute width-direction facing portions (21b, 21c), respectively, and the optical waveguide (12 The portions facing each other across the opening (21a) in the light propagation direction constitute a propagation direction facing portion (21d, 21e). In the first holding plate (21), the width direction facing portions (21b, 21c) hold the base material side portions (36, 37) from the first surface side. Also, in plan view, the left propagation direction facing portion (21d, 21e) in FIG. 5 (B) is located on the left side of the incident surface (31a) of the optical waveguide (12), and the right side in FIG. 5 (B). The propagation direction facing portions (21d, 21e) are located on the right side of the emission surface (31b) of the optical waveguide (12). That is, in plan view, the opening (21a) of the first holding plate (21) extends outward from the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12).

  The second holding plate (22) is formed in a rectangular frame shape as shown in FIG. The shape of the opening (22a) of the second holding plate (22) is a rectangle. The opening (22a) of the second holding plate (22) has a length in the longitudinal direction that is longer than the length of one side of the base material (31) (the length of the optical waveguide (12) in the light propagation direction). The length in the hand direction is shorter than the length of one side of the substrate (31) (the length in the width direction of the optical waveguide (12)). The 2nd holding plate (22) is laminated | stacked on the 2nd surface on the opposite side to the 1st holding member (21) side of a base material (31). The second holding plate (22) holds the base material side portions (36, 37) from the second surface side of the base material (31).

  In the second holding plate (22), the portions facing each other across the opening (22a) in the width direction of the optical waveguide (12) constitute the width direction facing portions (22b, 22c), respectively, and the optical waveguide (12 The portions facing each other across the opening (22a) in the light propagation direction constitute a propagation direction facing portion (22d, 22e). In the second holding plate (22), the width direction facing portions (22b, 22c) sandwich the base material side portions (36, 37) from the second surface side. In plan view, the left-side propagation direction facing portion (22d, 22e) in FIG. 5 (D) is located on the left side of the incident surface (31a) of the optical waveguide (12), and the right side in FIG. 5 (D). The propagation direction facing portions (22d, 22e) are located on the right side of the emission surface (31b) of the optical waveguide (12). That is, in plan view, the opening (22a) of the second holding plate (22) extends outward from the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12).

  The substrate frame plate (23) is formed in a rectangular frame shape as shown in FIG. The thickness of the substrate frame plate (23) is approximately equal to the total thickness of the substrate (31) and the coloring layer (32). The opening (23a) of the substrate frame plate (23) is formed in a square shape. The opening (23a) of the base material frame plate (23) has a side length substantially equal to a side length of the base material (31). Two cutout portions (23b, 23c) constituted by rectangular cutouts are formed on the inner periphery of the base frame plate (23). Each notch (23b, 23c) is formed by notching a portion facing the opening (23a) in the light propagation direction of the optical waveguide (12) from the inside. Each notch (23b, 23c) is formed at the center of the opening (23a) in the width direction of the optical waveguide (12). The two notches (23b, 23c) are formed symmetrically in FIG.

  In the present embodiment, the base frame plate (23) transmits the incident surface (31a) of the optical waveguide (12) to one end face of the optical waveguide (12) and the other end face of the optical waveguide (12). The exit surface (31b) of the waveguide (12) is formed. The entrance surface (31a) and the exit surface (31b) of the optical waveguide (12) are formed by the notches (23b, 23c) that are separated from the end surface of the substrate (31) among the inner surface of the substrate frame plate (23). Is formed. Each notch (23b, 23c) serves as an optical path for light incident on the incident surface (31a) or light emitted from the exit surface (31b).

  The substrate frame plate (23) is made of a material that does not transmit light, and covers the end surface of the substrate (31) while leaving the incident surface (31a) and the emission surface (31b) of the optical waveguide (12). Yes. In the base material (31), the space between the incident surface (31a) and the exit surface (31b) of the optical waveguide (12) constitutes the optical waveguide (12).

  Nothing other than the coloring layer (32) is in contact with the optical waveguide (12). In other words, the region of the surface of the optical waveguide (12) where the coloring layer (32) is not laminated is in contact with the gas over the entire region. In the present embodiment, the width of the optical waveguide (12) is set to 5 mm. When light emitted from a laser diode or light emitting diode propagates through the optical waveguide (12), the width of the optical waveguide is set to 10 mm or less.

  In the gas detection element (30), the gas introduction plate (26) is laminated on the side of the first holding plate (21) opposite to the base (31) side. The gas introduction plate (26) is provided so as to close the opening (21a) of the first holding plate (21). In the gas detection element (30), the gas chamber (20) partitioned by the first holding plate (21) and the gas introduction plate (26) is formed on the color development layer (32) side of the base material (31). .

  As shown in FIG. 5A, the gas introduction plate (26) has a circular first through hole (26a) and second through hole (26b) that penetrate the gas introduction plate (26) in the thickness direction. Is formed. The first through hole (26a) and the second through hole (26b) are formed symmetrically in FIG. 5A, and both open to the gas chamber (20). The first through hole (26a) is connected to the air supply passage (14) and constitutes an inflow passage (26a) for allowing the gas to be measured to flow into the gas chamber (20). The second through hole (26b) is connected to the exhaust passage (15) and constitutes an outflow passage (26b) for allowing the gas to be measured to flow out from the gas chamber (20).

  In addition, on the opposite side of the second holding plate (22) from the base material (31), the slit plate (27), the window frame plate (24), and the window holding plate (25) in this order from the base material (31) side. ) And are laminated. The acrylic window (28) is sandwiched between the slit plate (27) and the window holding plate (25) in a state of being accommodated in the opening (24a) of the window frame plate (24).

  As shown in FIG. 5E, the slit plate (27) is formed in a rectangular plate shape whose planar shape is slightly larger than the planar shape of the substrate (31). The slit plate (27) is laminated on the side opposite to the base (31) side of the second holding plate (22) so as to close the opening (22a) of the second holding plate (22).

  The slit plate (27) is formed with a rectangular first slit (27a) and a second slit (27b) extending in the short direction. The first slit (27a) and the second slit (27b) are formed symmetrically in FIG. 5 (E). As shown in FIG. 1, the first slit (27a) is located below the incident surface (31a) of the optical waveguide (12). The first slit (27a) is formed so that the light emitted from the light emitter (41) can reach the incident surface (31a) of the optical waveguide (12) straight. The first slit (27a) constitutes an incident opening (27a). On the other hand, the second slit (27b) is located below the emission surface (31b) of the optical waveguide (12). The second slit (27b) is formed so that the emitted light from the emission surface (31b) of the optical waveguide (12) can reach the light receiver (42) straight. The second slit (27b) constitutes an emission opening (27b).

  The window frame plate (24) is formed in a rectangular frame shape as shown in FIG. The shape of the opening (24a) of the window frame plate (24) is a rectangle. The opening (24a) of the window frame plate (24) is approximately the same size as the outer peripheral shape of the acrylic window (28). The window frame plate (24) is made of a member that does not transmit light, and prevents light from entering the end face of the acrylic window (28).

  The window holding plate (25) is formed in a rectangular frame shape as shown in FIG. The shape of the opening (25b) of the window holding plate (25) is a rectangle. The opening (25b) of the window holding plate (25) has a length in the longitudinal direction shorter than the length in the longitudinal direction of the acrylic window (28), and the length in the short direction is the length in the short direction of the acrylic window (28). Shorter than that. The window holding plate (25) prevents the acrylic window (28) from coming off.

  The acrylic window (28) is made of a transparent member. The acrylic window (28) is formed in a rectangular plate shape. The acrylic window (28) is provided so as to close the first slit (27a) and the second slit (27b).

<Detection operation>
The gas detection device (10) performs a detection operation for detecting the concentration of the target substance in the gas to be measured. In the gas detection device (10), power is supplied to the light emitter (41) with the air pump (16) stopped before the detection operation. Then, the light emitted from the light emitter (41) enters the optical waveguide (12) from the incident surface (31a), and the light incident on the optical waveguide (12) propagates by repeating total reflection and exits (31b). Exits from. The light receiver (42) that has received the light emitted from the emission surface (31b) outputs an optical signal representing the optical characteristics of the received light to the signal processing unit (17). When the air pump (16) is stopped, the intensity of the optical signal becomes a constant value as shown in FIG.

  The detection operation starts from this state. As shown in FIG. 8, in step 1 (ST1), the operation of the air pump (16) is started. During operation of the air pump (16), the gas in the gas chamber (20) is sucked into the air pump (16) in the exhaust passage (15), and the air to be measured such as room air is supplied to the air supply passage. It is introduced into the gas chamber (20) through (14).

  Here, when the air to be measured is introduced into the gas chamber (20), the air to be measured comes into contact with the color developing layer (32), and if the air to be measured contains the target substance, the target substance is changed to the color developing layer. It enters into the pores of (32) and reacts with the detection reagent. The coloring layer (32) develops color by the reaction between the detection reagent and the target substance. As the reaction proceeds, the back surface of the coloring layer (32) gradually changes color from the start of operation of the air pump (16).

  For example, when the target substance is formaldehyde and the detection reagent is an enaminone derivative, lutidine is generated by a chemical reaction between formaldehyde and the detection reagent. In the case of this lutidine, the wavelength of light in the band absorbed by color development is 405 nm. For this reason, in the optical waveguide, every time the incident light is reflected by the back surface of the coloring layer (32), the intensity of light having a wavelength of 405 nm decreases. As shown in FIG. 7, the intensity of the optical signal input to the signal processing unit (17) gradually decreases. The higher the formaldehyde concentration in the air to be measured, the greater the rate of decrease in the intensity of the optical signal per time, and the intensity of the optical signal reaches a minimum value. Further, the higher the formaldehyde concentration in the air to be measured, the longer it takes for the chemical reaction to saturate, and the longer the time required for the optical signal intensity to reach the minimum value.

  Subsequently, in step 2 (ST2), the signal processing unit (17) starts measurement by the rate method. In step 3 (ST3), the signal processing unit (17) acquires the intensity of the optical signal input from the photoreceptor (42) at a preset sampling time.

  Step 4 (ST4) is performed when the elapsed time from the execution time of step 1 (ST1) reaches a predetermined set time (for example, 1 minute). That is, step 4 (ST4) is performed when a predetermined set time has elapsed from the start of operation of the air pump (16). In step 4 (ST4), the signal processing unit (17) compares the current optical signal intensity with the determination threshold. When the current optical signal intensity is smaller than the determination threshold, the signal processing unit (17) proceeds to step 5 (ST5), and the current optical signal intensity is greater than or equal to the determination threshold. Shifts to step 5 (ST5).

  In step 5 (ST5), the signal processing unit (17) performs a first operation of detecting the concentration of the target substance using the rate method. In the first operation, the concentration of the target substance is detected based on the decrease rate (slope) of the intensity of the optical signal per time.

  In step 6 (ST6), the measurement is switched from the rate method to the end point method. The signal processing unit (17) performs a second operation of detecting the concentration of the target substance using the endpoint method. In the second operation, the intensity of the optical signal before starting the operation of the air pump (16) is I0, the intensity of the optical signal when reaching the end point is I, and -log (I / I0) with respect to the concentration C. Is calculated, and the concentration of the target substance is detected from the decrease in the intensity of the optical signal.

-Effect of the embodiment-
In the present embodiment, the gas chamber (20) from which the coloring layer (32) is exposed is formed using the first holding plate (21) that holds the base material (31). The periphery of the gas chamber (20) is partitioned by the first holding plate (21) and the closing member (26). The coloring layer (32) in the gas chamber (20) is not exposed to the outside of the gas detection element (30). The gas chamber (20) can be formed by a simple operation of stacking the gas introduction plate (26) on the first holding plate (21). Therefore, the gas detection element (30) capable of preventing unintentional gas supply to the surface of the color developing layer (32) can be manufactured relatively easily.

  In this embodiment, since the gas chamber (20) is formed by laminating the gas introduction plate (26) on the frame-shaped first holding plate (21), the thickness of the first holding plate (21). Thus, the height of the gas chamber (20) (the length of the base material (31) in the thickness direction) is determined. For this reason, it is possible to reduce the height of the gas chamber (20) only by reducing the thickness of the first holding plate (21). Therefore, it is possible to accurately form the gas chamber (20) having a small dead space volume and a low height.

  In this embodiment, the end surface of the base material (31) is blocked by the base material frame plate (23), leaving the entrance surface (31a) and the exit surface (31b) of the optical waveguide (12) facing each other. It is. On the end face of the base material (31), a region where light can enter is limited to the minimum necessary by the base material frame plate (23). For this reason, it can suppress that the light which is unrelated to the detection of a target substance permeates into an optical waveguide (12) from the end surface of a base material (31).

  Moreover, in this embodiment, the area | region which the light which reaches | attains a base material (31) can pass in the 2nd holding plate (22) side of a base material (31) is a 1st slit (27a) and a 2nd slit (27b). ). For this reason, it can suppress that the light which is unrelated to the detection of a target substance permeates into an optical waveguide (12) from the 2nd holding plate (22) side of a base material (31).

  In the present embodiment, the acrylic window (28) prevents gas from passing through the first slit (27a) and the second slit (27b). For this reason, gas can be prevented from entering the gas detection element (30) through the first slit (27a) and the second slit (27b).

  In the present embodiment, the method of detecting the concentration of the target substance is automatically performed from the rate method and the endpoint method according to the intensity of the optical signal after a predetermined set time has elapsed since the start of the operation of the air pump (16). Selected. The rate method is selected when the concentration of the target substance is high, and the endpoint method is selected when the concentration of the target substance is low. Here, when only the end point method is used, the concentration of the target substance can be accurately measured. However, when the concentration of the target substance is high, the detection time becomes long. When only the rate method is used, the detection time can be shortened, but there is a possibility that an error may occur in the detection result. In the present embodiment, the method for detecting the concentration of the target substance is automatically selected from the rate method and the endpoint method according to the concentration of the target substance. Therefore, when the concentration of the target substance is high, the detection time can be shortened by the rate method, and when the concentration of the target substance is low, the concentration of the target substance can be accurately detected by the end point method.

  In the present embodiment, the air pump (16) is provided in the exhaust passage (15) instead of the air supply passage (14). For this reason, the gas introduced into the gas chamber (20) in the detection operation is not diluted by the gas remaining in the air pump (16). Therefore, the reliability of the gas detection device (10) can be improved.

-Modification 1 of embodiment-
A first modification of the embodiment will be described. In this modification 1, the 2nd holding member (22) is comprised by the slit plate in the said embodiment. The frame-shaped second holding plate in the above embodiment is not provided.

  As shown in FIGS. 9 and 10, the slit plate (22) is laminated on the second surface of the base material (31) opposite to the first holding plate (21) side. As in the above embodiment, the slit plate (22) is formed with a first slit (22a) that constitutes the entrance opening (22a) and a second slit (22b) that constitutes the exit opening (22b). Has been. The first slit (22a) extends along the incident surface (31a) of the optical waveguide (12). The second slit (22b) extends along the emission surface (31b) of the optical waveguide (12). On the slit plate (22) side of the base material (31), the region through which light reaching the base material (31) can pass is limited to the first slit (22a) and the second slit (22b).

  Further, unlike the above-described embodiment, the first holding plate (21) is in contact with the first surface of the base material (31) around the entire opening (21a). The opening (21a) of the first holding plate (21) has a length in the longitudinal direction shorter than the length of one side of the base material (31). The first holding plate (21) is in contact with the end of the optical waveguide (12) on the light incident surface (31a) side and the end of the light exit surface (31b) side.

  Here, the surface of the first holding plate (21) has a certain degree of roughness. For this reason, in the area where the first holding plate (21) abuts on the light reflecting surface of the optical waveguide (12) (hereinafter referred to as “abutment area”), the same as the interface between the optical waveguide (12) and the gas. Total reflection occurs. This will be described below.

  The critical angle at which total reflection occurs is larger at the interface between the optical waveguide (12) and the solid than at the interface between the optical waveguide (12) and the gas because the solid has a higher absolute refractive index than the gas. Therefore, if the incident angle of light in the optical waveguide (12) is reduced to some extent, theoretically, total reflection occurs at the interface between the optical waveguide (12) and gas, but total reflection occurs at the interface between the optical waveguide (12) and solid. Will not occur. However, in Modification 1, since the surface of the first holding plate (21) has a certain degree of roughness, even if the incident angle of light in the optical waveguide (12) is reduced to some extent, the optical waveguide (12) and the gas As long as total reflection occurs at the interface, total reflection also occurs in the contact region where the solid contacts the optical waveguide (12). For this reason, the incident angle of light in the optical waveguide (12) can be reduced to some extent so that the electric field strength of the evanescent wave is increased.

  Moreover, in this modification 1, gas does not flow into a gas chamber (20) from between a base material (31) and a 1st holding plate (21). Accordingly, it is possible to more reliably prevent the gas from being unintentionally supplied to the surface of the coloring layer (32).

  In the first modification, light does not enter the gas chamber (20) from between the base material (31) and the first holding plate (21). Therefore, it can suppress that the intensity | strength of the light radiate | emitted from an optical waveguide (12) changes with stray light.

-Modification 2 of embodiment-
A second modification of the embodiment will be described. In the second modification, as shown in FIGS. 11 and 12, each of the first holding plates (21) is opposed to each other in the propagation direction (21d, 21e) on the light incident surface side end of the optical waveguide (12). And the surface (the upper surface in FIG. 11) of the end portion on the light emission surface side, facing each other with a gap (46) therebetween. Further, each propagation direction facing portion (22d, 22e) of the second holding plate (22) is a surface of an end portion on the light incident surface side and an end portion on the light exit surface side of the optical waveguide (12) (FIG. 11). The lower surface) with a gap in between.

  Specifically, the gas detection element (30) is formed in a rectangular shape in plan view. The gas detection element (30) includes a first holding plate (21), a second holding plate (22), a gas introduction plate (26), and a bottom plate in addition to the base material (31) and the coloring layer (32). (29) and two side plates (38, 39). In the gas detection element (30), these four members are laminated in the order of the gas introduction plate (26), the first holding plate (21), the second holding plate (22), and the bottom plate (29). . Each side plate (38, 39) is sandwiched between a gas introduction plate (26) and a bottom plate (29).

  In the second modification, each end surface of the base material (31) is exposed at each end surface (left and right end surfaces in FIG. 11) extending in the short direction of the gas detection element (30). For this reason, light can be incident on one end face of the optical waveguide (12) of the substrate (31) from the outside, and the light emitted from the other end face of the optical waveguide (12) can be received externally. The base material (31) includes an optical waveguide (12) through which light propagates in the longitudinal direction of the gas detection element (30) (left and right direction in FIG. 11).

  The first holding plate (21) is formed in a rectangular frame shape. As shown in FIG. 13, in the first holding plate (21), the width direction facing portions (21b, 21c) hold the base material side portions (36, 37) from the first surface side. Further, each propagation direction facing portion (21d, 21e) is thinner than the width direction facing portion (21b, 21c). As shown in FIG. 12, the facing surface (45) on the base material (31) side of each propagation direction facing portion (21d, 21e) is the upper surface of the end portion of the optical waveguide (12) across the gap (46). Facing (47). The facing surface (45) is formed as a flat surface parallel to the upper surface (47) of the end of the optical waveguide (12).

  The second holding plate (22) is formed in a rectangular frame shape. As shown in FIG. 13, in the second holding plate (22), the width direction facing portions (22b, 22c) hold the base material side portions (36, 37) from the second surface side. Further, each propagation direction facing portion (22d, 22e) is thinner than the width direction facing portion (22b, 22c). As shown in FIG. 12, the facing surface on the base material (31) side of each propagation direction facing portion (22d, 22e) faces the lower surface of the end portion of the optical waveguide (12) with a gap interposed therebetween. The opposing surface is formed as a flat surface parallel to the lower surface of the end portion of the optical waveguide (12).

—Modification 3 of Embodiment—
A modification 3 of the embodiment will be described. In the gas detection device (10) of the third modification, the gas around the gas detection element (30) in the casing (11) can be discharged out of the casing (11) by the air pump (16) in the exhaust passage (15). It is configured. In the casing (11), the gas detection element (30) is disposed in the installation space (50).

  The suction side of the air pump (16) is connected not only to the gas chamber (20) but also to the installation space (50). In the gas detection device (10), the air pump (16) sucks the gas in the gas chamber (20) and discharges it outside the casing (11), and the air pump (16) is installed in the installation space (50). The second operation of sucking gas and discharging it out of the casing (11) can be switched. The first operation is performed during the detection operation. The second operation is performed, for example, before the detection operation.

  In addition to the air pump (16) in the exhaust passage (15), an air pump (16) for discharging the gas around the gas detection element (30) in the casing (11) to the outside of the casing (11) is provided. Also good.

  In the third modification, before the gas is introduced into the gas chamber (20), the gas around the gas detection element (30) in the casing (11) is discharged out of the casing (11). For this reason, it can avoid that the detection result of a detection operation receives the influence of the gas of the last detection operation.

<< Other Embodiments >>
About the said embodiment, it is good also as following structures.

  About the said embodiment, the air pump (16) may be provided in the air supply path (14). In this case, the gas to be measured is pushed into the gas chamber (20) by the air pump (16).

  In the above embodiment, the coloring layer (32) may be composed of a polymer film or a monomolecular film that develops color by reaction with the target substance.

  Moreover, about the said embodiment, the gas detection apparatus (10) may be comprised so that the presence or absence of a target substance may be detected.

  In the above embodiment, a flexible sealing material may be used to close the end surface of the base material (31) other than the incident surface (31a) and the exit surface (31b) of the optical waveguide (12).

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a gas detection element including a base material constituting an optical waveguide, and a gas detection device including the gas detection element.

DESCRIPTION OF SYMBOLS 10 Gas detection apparatus 12 Optical waveguide 14 Supply path 15 Exhaust path 16 Air pump 17 Signal processing part (signal processing means)
20 Gas chamber 21 First holding plate (first holding member)
22 Second holding plate (second holding member)
23 Substrate frame plate (end face closing member)
26 Gas introduction plate (blocking member)
27 Slit plate (opening forming member)
28 Acrylic window (opening closing member)
DESCRIPTION OF SYMBOLS 30 Gas detection element 31 Base material 31a Incident surface 31b Outgoing surface 32 Color development layer 41 Light emitter 42 Light receiver

Claims (7)

A base material (31) which is formed in a flat plate shape and constitutes an optical waveguide (12) in which one end face of the opposite end face is a light incident face (31a) and the other end face is a light exit face (31b); ,
Coloring layer (32) which is laminated on the light reflecting surface of the optical waveguide (12) among the surface of the base material (31) and develops color by reaction with the target substance using a predetermined chemical substance contained in the gas as the target substance A gas detection element comprising:
A first holding member (21) which is formed in a frame shape having an opening and is laminated on the base material (31) so that the coloring layer (32) faces the opening, and the opening constitutes a gas chamber (20) When,
A second holding member (22) stacked on the opposite side of the base (31) from the first holding member (21) side and holding the base (31) together with the first holding member (21); ,
The first holding member (21) is laminated on the side opposite to the base (31) side so as to close the opening of the first holding member (21), and allows gas to flow into the gas chamber (20). A gas detection element comprising: an inflow passage (26a); and a closing member (26) formed with an outflow passage (26b) for allowing gas to flow out of the gas chamber (20). In claim 1,
The gas detection element, wherein the first holding member (21) is in contact with the surface of the base material (31) over the entire periphery of the opening. In claim 1 or 2,
The optical waveguide is formed in a frame shape having an opening, and is provided between the first holding member (21) and the second holding member (22) in a state where the substrate (31) is accommodated in the opening. (12) has an optical path in the corresponding part of the entrance surface (31a) and the exit surface (31b), and closes the end surface of the base material (31) around the entrance surface (31a) and the exit surface (31b) A gas detection element comprising a frame-shaped closing member (23) that performs the above-described operation. In any one of Claims 1 thru | or 3,
The second holding member (22) is formed in a flat plate shape whose planar shape is larger than that of the base material (31),
The second holding member (22) includes an incident opening (22a) through which light incident on the incident surface (31a) of the optical waveguide (12) passes, and an output surface (31b) of the optical waveguide (12). A gas detection element characterized in that an emission opening (22b) for allowing light emitted from the light to pass therethrough is formed. In any one of Claims 1 thru | or 3,
The second holding member (22) is formed in a frame shape having an opening, and the opening is formed to extend outward from the incident surface (31a) and the emitting surface (31b) of the optical waveguide (12). on the other hand,
The second holding member (22) is laminated on the side opposite to the base (31) side so as to close the opening of the second holding member (22), and is formed on the incident surface (31a) of the optical waveguide (12). An opening forming member (27) in which an incident opening (27a) for allowing incident light to pass through and an emission opening (27b) for allowing light incident on the exit surface (31b) of the optical waveguide (12) to pass therethrough are formed. A gas detection element comprising: In claim 4 or 5,
A gas detection element comprising an opening closing member (28) configured by a transparent member and provided so as to close the entrance opening (22a, 27a) and the exit opening (22b, 27b) . A gas detection element (30) according to any one of claims 1 to 6;
A light emitter (41) that emits light to be incident on the optical waveguide (12);
A light receiver (42) that receives light emitted from the optical waveguide (12) and outputs an optical signal representing the optical characteristics of the received light;
A gas detection apparatus comprising: a signal processing means (17) for receiving the optical signal and detecting the concentration or presence of the target substance based on a change in the optical signal.

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