JP2018013349A - Flow cell, and sensor including flow cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow cell disposed in a tube through which a fluid as a detection object flows, capable of preventing bubbles from being retained in the fluid.SOLUTION: Disclosed flow cell has a structure 3 in which a space 2 is formed. The structure 3 has a first opening 19 communicating with the space 2, a second opening 20, and a third opening 21. The flow cell is configured so that for the length in the direction perpendicular to the extending direction of the space 2, the length of the center part of the space 2 is shorter than the length of the first opening portion 19 in the direction.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to a device such as a fluid component detection device that detects the concentration of a fluid component by using absorption characteristics of light such as infrared rays.

  Conventionally, a sensor as shown in Patent Document 1 is known as a sensor for detecting a concentration of a fluid to be detected from infrared absorption characteristics by placing a flow channel cell in a pipe.

Japanese Patent No. 589958

  However, in order to reduce the output of infrared rays from the light emitting element and reduce the power consumption of the sensor, it is necessary to reduce the height of the flow channel cell. When the height is reduced, there is a problem that even if the fluid to be detected is flowed, all the air in the flow path cell cannot be discharged, and bubbles remain.

  An object of the present disclosure is to solve the above-described problems and to provide a flow channel cell that can suppress the retention of bubbles when a fluid to be detected flows even if the height of the flow channel cell is lowered.

  In order to solve the above-described problem, the flow channel cell of the present disclosure has a structure in which a space is provided, and the structure includes a first opening and a second opening that communicate with the space. The third opening is provided, and the length in the direction perpendicular to the extending direction of the space is such that the length of the central portion of the space is shorter than the length of the first opening in the direction. did.

  With the above configuration, the present disclosure can reduce the output of the light emitting element without hindering the flow of the fluid to be detected, and can reduce the power consumption of the sensor.

Side sectional view of flow path cell of embodiment 1 AA line cross-sectional view of the same channel cell The figure which shows the positional relationship of the sensor using the same flow path cell Side sectional view of flow path cell of embodiment 2 BB line cross section of the same channel cell The figure which shows the positional relationship of the sensor using the same flow path cell Side sectional view of flow path cell of embodiment 3 CC line cross section of the same flow cell The figure which shows the positional relationship of the sensor using the same flow path cell

Hereinafter, a flow channel cell according to an embodiment and a sensor using the flow channel cell will be described with reference to the drawings. In addition, in each drawing, about the same structure, the same code | symbol is attached | subjected and description is abbreviate | omitted. In addition, each component in each embodiment may be arbitrarily combined within a consistent range. The configuration in each embodiment can be changed without departing from the scope of the invention.
(Embodiment 1)
The flow path cell and sensor using the flow path cell according to the first embodiment will be described below with reference to the drawings.

  FIG. 1 is a side sectional view of a flow path cell according to the first embodiment, FIG. 2 is a cross-sectional view taken along line AA of the flow path cell, and FIG. 3 is a diagram showing a positional relationship of a sensor using the flow path cell.

  As shown in FIGS. 1 to 3, the sensor 1 includes a flow channel cell 4 having a structure 3 in which a space 2 is provided, a tube portion 5 having the flow channel cell 4 therein, and a tube portion 5. The light emitting element 6 disposed on one side of the tube, the light receiving element 7 disposed on the other side of the tube portion 5, the first mounting member 8 for mounting the light emitting element 6 on the tube portion 5, and the tube portion of the light receiving element 7 5 has a second attachment member 9 to be attached. Gasoline or the like, which is a fluid to be detected, flows in the pipe portion 5, and the fluid to be detected also flows in the flow path cell 4 provided in the pipe portion 5. The infrared light incident on the flow path cell 4 from the light emitting element 6 is absorbed by the detected fluid when passing through the detected fluid flowing in the flow path cell 4, and the amount of light received by the light receiving element 7 decreases. The concentration of the fluid to be detected can be detected by processing the output of the light receiving element 7 with a signal processing circuit (not shown). Hereinafter, the extending direction of the tube portion 5 will be described as the X-axis direction, the extending direction of the space 2 perpendicular to the X-axis direction as the Y-axis direction, and the direction perpendicular to the extending direction of the space 2 will be described as the Z-axis direction.

  The structure 3 includes a first substrate 11 having a first main surface 10 and a second substrate 13 having a second main surface 12, and the first substrate 11 and the second substrate 13 are The first main surface 10 and the second main surface 12 are connected so as to face each other. The first substrate 11 and the second substrate 13 are formed in a rectangular shape when viewed from above, and the second substrate 13 has connection portions 14 at the four corners on the second main surface 12 side. A space between the first substrate 11 and the second substrate 13 via the connection portion 14 becomes the space 2 of the structure 3. The first substrate 11 and the second substrate 13 are bonded by direct bonding via the connection portion 14. Note that the bonding method of the first substrate 11 and the second substrate 13 is not limited to direct bonding, and may be bonded by, for example, glass frit bonding. Further, the connecting portion 14 is formed integrally with the second substrate 13, but this is not a limitation, and a spacer is sandwiched between the first substrate 11 and the second substrate 13 to connect the first substrate 11 and the second substrate 13. The second substrate 13 may be bonded to the spacer. Further, the structure 3 is formed so that the first substrate 11 and the second substrate 13 are sandwiched between the first substrate 11 and the second substrate 13 without processing the first substrate 11 and the second substrate 13. May be. Further, the first substrate 11 and the second substrate 13 are not limited to a rectangular shape, and may be other shapes such as a polygon such as a pentagonal shape or a circular shape when viewed from above.

  The structure 3 has a first side surface 15, a second side surface 16, a third side surface 17, and a fourth side surface 18. The first side surface 15 and the second side surface 16 are arranged in the X-axis direction, and the third side surface 17 and the fourth side surface 18 are arranged in the Y-axis direction. The second side surface 16 is on the opposite side of the first side surface 15 in the X-axis direction, and the fourth side surface 18 is on the opposite side of the third side surface 17 in the Y-axis direction. The first side surface 15 has a first opening 19, the second side surface 16 has a second opening 20, the third side surface 17 has a third opening 21, and the fourth side A side opening 18 has a fourth opening 22. The flow path cell 4 is arranged in the pipe part 5 so that the detected fluid flows in the X-axis direction in the pipe part 5 and the detected fluid flows from the first opening 19. For this reason, the fluid to be detected flows in from the first opening 19 and flows out from the second to fourth openings 22, 23, and 24. Flows in the space 2 inside the structure 3.

The first substrate 11 and the second substrate 13 are made of silicon. The first main surface 10 of the first substrate 11 is provided with an inclined surface 23 that is separated from the central portion toward the first opening 19 and the second opening 20. For this reason, the thickness of the first substrate 11 is the thickest at the central portion and becomes thinner toward the first opening 19 and the second opening 20. The thickness of the first substrate 11 is the smallest at the first opening 19 and the second opening 20. The surface orientation of the first main surface 10 is (110), and the surface orientation of the slope 23 is (111). For this reason, the angle of the inclined surface 23 with respect to the first main surface 10 is about 35 degrees, and the thickness of the first substrate 11 changes gently. Thereby, the resistance when the fluid to be detected flows on the inclined surface 23 becomes small, and it becomes difficult to prevent the flow of the fluid to be detected. In addition, the slope 23 can be easily formed by forming the slope 23 according to the (111) plane of the first substrate 11. Although the surface orientation of the first main surface 10 is (110), the inclined surface 23 can be formed even if the surface orientation of the first main surface 10 is another surface orientation such as (100). In this case, if the inclined surface 23 is formed in accordance with the surface orientation of the first substrate 11, the angle with respect to the first main surface 10 is about 55 degrees, so that the flow of the detected fluid is hindered. In order to avoid this, it may be formed by cutting so that the angle of the slope 23 becomes gentler, but the slope of the slope 23 is smaller than when the plane orientation of the first main surface 10 is (110). Increases the labor of formation. For this reason, it is most preferable that the surface orientation of the first main surface 10 is (110). In addition, although the slope 23 was formed according to the surface (111) surface of the 1st board | substrate 11, you may form so that the side cross section of the slope 23 may become a curved surface shape. A flat surface is formed between the slope 23 on the first opening 19 side and the slope 23 on the second opening 20 side. The first substrate 11 has the slopes 23 only on the first opening 19 side and the second opening 20 side, but the slopes are also provided on the third opening 21 side and the fourth opening 22 side. It may be provided.

  The length in the direction perpendicular to the extending direction of the space 2 (Z-axis direction) is equal to the length L1 in the Z-axis direction of the central portion of the space 2 because the inclined surface 23 is provided on the first substrate 11. Is shorter than the length L2 of the first opening 19 in the Z-axis direction and the length L3 of the second opening 20 in the Z-axis direction. In the flow path cell 4, the length L2 of the first opening 19 and the length of the second opening 20 are the same, but they may be different. Since infrared rays are transmitted through the central portion of the space 2, it is preferable that the length L1 in the Z-axis direction of the central portion of the space 2 is 10 μm to 100 μm. As a result, the amount of attenuation when infrared light passes through the fluid to be detected flowing through the space 2 is small, so that the light receiving element 7 can detect even if the output of the light emitting element 6 is small. Thereby, the power consumption of the light emitting element 6 can be reduced. Further, since the length L1 in the Z-axis direction of the central portion of the space 2 is 10 μm or more, the infrared light is sufficiently absorbed by the detected fluid when the infrared light passes through the detected fluid, and the amount of light received by the light receiving element 7 is reduced. Therefore, the concentration of the fluid to be detected can be detected with high accuracy.

  When the inclined surface 23 is provided on the first substrate 11, the first opening 19 and the second opening 20 are sufficiently wide, and the fluid to be detected flows into the first opening 19. The resistance to the fluid to be detected when flowing out from the second opening 20 is reduced. For this reason, inflow and outflow of the fluid to be detected to the structure 3 are facilitated.

  Before the fluid to be detected flows, air exists in the structure 3 and air is discharged from the structure 3 when the fluid to be detected flows, but the length of the space 2 in the Z-axis direction is reduced. As a result, the fluid to be detected is less likely to flow through the space 2 and air is less likely to be discharged. Thereby, bubbles stay in the space 2. When infrared rays are transmitted through the fluid to be detected while bubbles remain in the space 2, the amount of reduction of infrared rays changes due to the bubbles. For this reason, the detection accuracy of the sensor 1 decreases.

However, since the flow path cell 4 is provided with the third opening 21 and the fourth opening 22 in the structure 3, air bubbles are also discharged from the third opening 21 and the fourth opening 22. Is done. For this reason, even if the length of the space 2 in the Z-axis direction is shortened, the bubbles can be sufficiently discharged. Therefore, the length of the central portion of the space 2 in the Z-axis direction without reducing the detection accuracy of the sensor 1. L1 can be shortened. Thereby, power consumption can be reduced without degrading the accuracy of the sensor 1. Note that the retention of bubbles can be prevented if either one of the third opening 21 and the fourth opening 22 is provided, but the third opening 21 and the fourth opening 22 Since both are provided, the retention of bubbles can be prevented more.

  The first main surface 10 and the second main surface 12 are provided with antireflection films (not shown). By providing the antireflection film, the transmittance of infrared rays is improved, and the sensitivity of the sensor 1 is improved. If the antireflection film is provided on one of the first main surface 10 and the second main surface 12, the sensitivity of the sensor 1 can be improved, but the flow path cell 4 has the first main surface 10. Since the antireflection film is provided on both the second main surface 12 and the second main surface 12, the sensitivity of the sensor 1 can be further improved.

  The light emitting element 6 uses a platinum thin film resistance element capable of emitting infrared rays. A light emitting diode capable of emitting infrared light may be used. The light emitting element 6 is contained in the first package 24. A first silicon cap 25 is provided at the tip of the light emitting element 6 of the first package 24. The light emitting element 6 is disposed on a spacer 26 provided in the first package 24. A semiconductor bare chip is used for the light emitting diode. The light emitting element 6 emits infrared light having a wavelength that is easily absorbed by the gas to be detected. In the sensor 1, infrared rays having a wavelength of 2 μm to 15 μm are used. The light emitting element 6 is disposed on one side of the tube portion 5 in the Z-axis direction, and infrared rays are incident on the flow path cell 4 in the tube portion 5. The infrared wavelength is 2 μm to 15 μm. By using this wavelength, the concentration of the fluid to be detected can be accurately detected. Note that the wavelength range to be used may be further narrowed according to the use application of the sensor 1. The wavelength range can be narrowed with an optical bandpass filter (not shown) that matches the absorption wavelength specific to the fluid component to be measured. Further, by combining the light emitting element 6, the light receiving element 7 and the bandpass filter corresponding to a plurality of types of wavelengths, it becomes possible to simultaneously measure a plurality of components in the fluid.

  The light receiving element 7 uses a semiconductor bare chip. The light receiving element 7 is placed in the second package 27. A first silicon cap 25 is provided at the tip of the light receiving element 7 of the second package 27. The light receiving element 7 is disposed on a spacer 26 provided in the second package 27. The light receiving element 7 is provided on the other side of the tube portion 5 in the Z-axis direction, and is arranged so that infrared light transmitted through the flow path cell 4 enters the light receiving element 7.

  The tube portion 5 is formed in a cylindrical shape through which the fluid to be detected can flow, and the body portion 28 in which the flow path cell 4 is disposed, and joints 29 at both ends of the body portion 28 in the X-axis direction. have. Since the fluid to be detected flows in the extending direction (X-axis direction) of the tube portion 5 and the first opening 19 is arranged facing the extending direction of the tube portion 5, the fluid to be detected is a flow channel cell. 4 flows in. Holes (not shown) are opened on the − side and + side in the Z-axis direction of the main body portion 28, and the first package 24 is attached to the holes via the first attachment member 8, and the second package The second package 27 is attached via the attachment member 9. The first mounting member 8 is provided with a second silicon cap 30 that is resin-sealed with a resin 31. Infrared light emitted from the light emitting element 6 enters the flow path cell 4 from the second silicon cap 30. The second attachment member 9 is provided with a third silicon cap 32 sealed with a resin 31. Infrared light that has passed through the flow path cell 4 enters the light receiving element 7 from the third silicon cap 32. The first silicon cap 25 and the third silicon cap 32 are sealed with resin, so that hermeticity is enhanced. The first attachment member 8 and the second attachment member 9 are connected to the pipe portion 5 using an O-ring 33. When the sensor 1 is used, a member for flowing a fluid to be detected such as a hose or a pipe is attached to the joint 29 and is fixed by a band or the like. The length of the main body portion 28 in the Z-axis direction is the same as the length of the flow path cell 4 in the Z-axis direction. When the flow path cell 4 is disposed in the tube portion 5, the first substrate 11 becomes the second substrate 11. The second substrate 13 is in close contact with the third silicon cap 32 in close contact with the silicon cap 30. As a result, the infrared light emitted from the light emitting element 6 passes through the fluid to be detected only in the space 2 of the flow path cell 4. Thereby, the concentration of the fluid to be detected can be detected with high accuracy.

The sensor 1 has been described with the structure in which the first substrate 11 is disposed on the negative side in the Z-axis direction. However, the second substrate 13 may be disposed on the negative side in the Z-axis direction. good.
(Embodiment 2)
The sensor according to Embodiment 2 will be described below with reference to the drawings. Note that differences from the sensor of the first embodiment will be particularly described.

  4 is a side sectional view of the flow path cell according to the second embodiment, FIG. 5 is a cross-sectional view taken along the line BB of the flow path cell, and FIG. 6 is a diagram showing the positional relationship of a sensor using the flow path cell.

  The sensor 41 according to the second embodiment includes a flow path cell 42, a tube part 5 provided with the flow path cell 42 therein, a light emitting element 6 and a light receiving element 7 disposed on one side of the tube part 5, and a light emitting element. 6 and a second silicon cap 30 for attaching the light receiving element 7 to the tube portion 5 has a first attachment member 8 sealed with resin.

  A reflective film 43 made of gold or the like is formed on the second main surface 12. The flow path cell 42 is disposed in the tube portion 5 so that the first opening portion 19 faces the X-axis direction. The first substrate 11 is in close contact with the second silicon cap 30.

  The light emitting element 6 and the light receiving element 7 are placed in the third package 44 and arranged on the negative side of the tube portion 5 in the Z-axis direction. Infrared light emitted from the light emitting element 6 enters the flow path cell 42 from the first substrate 11, is reflected by the reflective film 43, and enters the light receiving element 7. The third package 44 is provided with a support member 45, and the light emitting element 6 and the light receiving element 7 are disposed on the support member 45. The normal direction of the surface where the light emitting element 6 and the light receiving element 7 of the support member 45 are arranged is inclined with respect to the Z-axis direction. As a result, the infrared light emitted from the light emitting element 6 is incident at an angle θ with respect to the normal direction of the reflective film 43. Since the light receiving surface of the light receiving element 7 is also inclined with respect to the Z-axis direction, the infrared light reflected by the reflective film 43 is incident on the light receiving surface perpendicularly. Thus, since the normal direction of the surface on which the light emitting element 6 and the light receiving element 7 are arranged is inclined with respect to the Z-axis direction, the light emitting element 6 and the light receiving element 7 are arranged in the same direction with respect to the tube portion 5. In addition, the light receiving element 7 can receive infrared rays.

  In the sensor 41, the light emitting element 6 and the light receiving element 7 are integrally disposed in the third package 44 and disposed on one side of the tube portion 5, thereby reducing the number of members constituting the sensor 41. Yes. Further, since infrared rays are reflected by the second main surface 12, the flow path cell 42 only needs to be in close contact with only the second silicon cap 30, so that the length of the body portion 28 of the tube portion 5 in the Z-axis direction is long. It is not necessary to adjust the length to the length of the flow path cell 42 in the Z-axis direction, and it can be designed freely. In addition, since the third package 44 is disposed only on one side of the tube portion 5, the sensor 41 can be reduced in size.

  The infrared light that has entered the flow path cell 42 enters the space 2 and is reflected by the reflective film 43. Since infrared rays are reflected in the space 2, if the length is halved with respect to the structure of the flow path cell 42 of the first embodiment, the same effect as in the first embodiment can be obtained. For this reason, it is preferable that the length of the space 2 of the structure 3 in the Z-axis direction is 5 μm or more and 50 μm or less.

In addition, although the structure which provided the reflecting film 43 in the 2nd main surface 12 was demonstrated, you may provide the reflecting film 43 in the 1st main surface 10. FIG. In this case, the second substrate 13 may be disposed so as to be in close contact with the second silicon cap 30.
(Embodiment 3)
The sensor according to Embodiment 3 will be described below with reference to the drawings. Note that differences from the sensor of the second embodiment will be particularly described.

  7 is a side sectional view of the flow path cell according to the third embodiment, FIG. 8 is a cross-sectional view taken along the CC line of the flow path cell, and FIG. 9 is a diagram showing the positional relationship of the sensor using the flow path cell.

  The sensor 51 according to Embodiment 3 includes a flow channel cell 52, a tube part 5 provided with the flow channel cell 52 therein, a light emitting element 6 and a light receiving element 7 disposed on one side of the tube part 5, and a light emitting element. 6 and a second silicon cap 30 for attaching the light receiving element 7 to the tube portion 5 has a first attachment member 8 sealed with resin.

  The flow path cell 52 is provided with a concave portion 53 on the second main surface 12 and a reflective film 43 using gold or the like in the concave portion 53. The recess 53 is formed in an elliptical curved surface shape. The flow path cell 52 is disposed in the tube portion 5 so that the first opening portion 19 faces the X-axis direction. The first substrate 11 is in close contact with the second silicon cap 30.

  The light emitting element 6 and the light receiving element 7 are placed in the fourth package 54 and arranged on the negative side of the tube portion 5 in the Z-axis direction. The infrared light emitted from the light emitting element 6 enters the flow path cell 52 from the first substrate 11, is reflected by the reflective film 43, and enters the light receiving element 7. The light emitting element 6 is disposed at the focal position of the recess 53, and infrared light is emitted from the light emitting element 6 in the Z-axis direction. The light receiving element 7 is disposed at the focal position of the recess 53 and is disposed such that the light receiving surface faces the Z-axis direction.

  The sensor 51 can arrange | position the light emitting element 6 and the light receiving element 7 in the focus position of a recessed part by forming the recessed part 53 in elliptical curved surface shape. For this reason, since it is not necessary to arrange | position so that the light emitting element 6 and the light receiving element 7 may incline with respect to a Z-axis direction, the sensor 1 can be formed easily.

  In the flow path cell of the present disclosure, bubbles do not easily stay when a fluid to be detected flows, and power consumption can be reduced without lowering the sensitivity of the sensor. Is suitable.

DESCRIPTION OF SYMBOLS 1, 41, 51 Sensor 2 Space 3 Structure 4, 42, 52 Flow path cell 5 Tube part 6 Light emitting element 7 Light receiving element 8 1st attachment member 9 2nd attachment member 10 1st main surface 11 1st Substrate 12 Second main surface 13 Second substrate 14 Connection portion 15 First side surface 16 Second side surface 17 Third side surface 18 Fourth side surface 19 First opening portion 20 Second opening portion 21 Third Opening 22 of the second opening 23 Slope 24 First package 25 First silicon cap 26 Spacer 27 Second package 28 Main body 29 Joint 30 Second silicon cap 31 Resin 32 Third silicon cap 33 O -Ring 43 Reflective film 44 Third package 45 Support member 53 Concave portion 54 Fourth package

Claims (19)

It has a structure with a space inside,
The structure is provided with a first opening, a second opening, and a third opening that communicate with the space;
The length of the space in the direction perpendicular to the extending direction of the space is a flow path cell in which the length of the central portion of the space is shorter than the length of the first opening in the direction. The second opening is provided on the opposite side of the first opening with respect to the structure,
The flow path cell according to claim 1, further comprising a fourth opening on the opposite side of the third opening with respect to the structure. 3. The flow path cell according to claim 1, wherein a length of the central portion of the space in the direction is shorter than a length of the second opening in the direction. The structure includes a first substrate having a first main surface and a second substrate having a second main surface;
The flow path cell according to any one of claims 1 to 3, wherein the first substrate and the second substrate are joined so that the first main surface and the second main surface face each other. The flow path cell according to claim 4, wherein the second substrate has a connection portion, and is joined to the first substrate at the connection portion. 5. The slope according to claim 4, wherein the first main surface is provided with a slope that is separated from the second substrate from a central portion toward the first opening and the second opening. Channel cell. The first substrate is formed of silicon;
The plane orientation of the first main surface is (110),
The flow path cell according to claim 6, wherein the surface orientation of the slope is (111). The flow path cell according to claim 6, wherein a side surface of the inclined surface has a curved surface shape. The flow path cell according to any one of claims 3 to 8, wherein an antireflection film is provided on at least one of the first main surface and the second main surface. The flow path cell according to claim 1, wherein a length of the central portion of the space in the direction is 10 μm or more and 100 μm or less. The flow path cell according to any one of claims 3 to 9, wherein a reflective film is provided on the first main surface. The flow path cell according to claim 3, wherein a reflection film is provided on the second main surface. A concave portion having an elliptical curved surface is provided in a central portion of the second main surface;
The flow path cell according to claim 12, wherein the reflective film is provided in the concave portion. 14. The flow path cell according to claim 11, wherein a length of the central portion of the space in the direction is not less than 5 μm and not more than 50 μm. A flow path cell according to any one of claims 1 to 10,
A pipe part having the flow channel cell therein;
A light-emitting element that is provided on one side of the tube portion and injects infrared rays into the flow path cell;
A sensor provided on the other side of the tube portion for receiving infrared light transmitted through the flow channel cell, wherein the flow channel has the first opening facing the extending direction of the tube portion; The light emitting element is connected to the tube portion via a first attachment member in which a first silicon cap is resin-sealed,
The light receiving element is connected to the tube portion via a second attachment member in which a second silicon cap is resin-sealed,
The sensor according to claim 15, wherein the flow path cell is in close contact with the first silicon cap and the second silicon cap. A flow path cell according to claim 11 or 14,
A pipe part having the flow channel cell therein;
A light-emitting element that is provided on one side of the tube part and injects infrared rays into the second substrate;
A light-receiving element that is provided on one side of the tube portion and receives infrared rays reflected by the reflective film, and the flow path cell has the first opening portion facing the extending direction of the tube portion;
The light emitting element is a sensor that emits the infrared light such that the infrared light is incident at an angle with respect to a normal direction of the reflective film. A flow path cell according to claim 12 or 14,
A pipe part having the flow channel cell therein;
A light-emitting element that is provided on one side of the tube portion and injects infrared light into the first substrate;
A light-receiving element that is provided on one side of the tube portion and receives infrared rays reflected by the reflective film, and the flow path cell has the first opening portion facing the extending direction of the tube portion;
The light emitting element is a sensor that emits the infrared light such that the infrared light is incident at an angle with respect to a normal direction of the reflective film. A flow path cell according to claim 13;
A pipe part having the flow channel cell therein;
A light-emitting element that is provided on one side of the tube portion and injects infrared light into the first substrate;
A light-receiving element that is provided on one side of the tube portion and receives infrared rays reflected by the reflective film, and the flow path cell has the first opening portion facing the extending direction of the tube portion;
The light emitting element and the light receiving element are arranged at the focal point of the recess.

Images