JP4427659B2 - Gas detection device - Google Patents

Description

The present invention relates to a gas detection apparatus equipped with a circulating liquid delivery device.

As a conventionally known gas detection device, for example, an electrode is provided in a detection tank in which an internal liquid is accommodated so as to be in contact with the internal liquid, and gas is not transmitted to the bottom surface of the detection tank. There is a diaphragm type gas sensor provided with a permeable diaphragm (Patent Document 1 below).
Japanese Utility Model Publication No. 53-70289

In the gas sensor having such a configuration, in order to ensure a quick and stable response and to reduce the size of the apparatus, the distance between the diaphragm and the electrode is reduced, and the gas permeated through the diaphragm and the internal liquid are reduced. There is a demand to reduce the volume of the reaction region (detection tank) where the reaction occurs.
However, in such a case, there is a problem that the internal liquid around the diaphragm is easily dried, and as a result, the sensor performance is easily deteriorated. Further, the smaller the internal liquid, the more easily the concentration of the component to be measured and the interference component in the internal liquid is increased. As a result, the internal liquid and the electrode surface may be altered and the sensor performance may be deteriorated.

  Therefore, the present inventors can provide a reaction region in a part of the closed circuit, and if the internal liquid can be circulated in the closed circuit, the volume of the reaction region can be reduced and the distance between the diaphragm and the electrode can be reduced. The inventors have come up with the idea that the above-mentioned problem can be solved, but a liquid delivery device that can smoothly circulate the internal liquid in a closed circuit including such a narrow channel has not been developed yet.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circulating liquid feeding device that can smoothly circulate a liquid even in a closed circuit including a narrow channel.
Another object of the present invention is to provide a gas detection device capable of obtaining high sensor performance by preventing drying of the internal liquid and alteration of the internal liquid and the electrode surface accompanying an increase in the concentration of the internal liquid. To do.

In order to solve the above-mentioned problems, a gas detection device of the present invention is capable of containing a liquid and has a variable volume pump unit, and an enlarged flow channel connected to the pump unit and having a cross-sectional area expanding toward the pump unit. A reduced diameter channel that is connected to the pump unit and whose cross-sectional area decreases toward the pump unit, a communication channel that connects the expanded diameter channel and the reduced diameter channel, and a communication channel that communicates with the communication channel, A circulating liquid feeding device comprising a buffer unit for storing a compressible fluid and a driving device capable of changing the volume of the pump unit, and a gas-liquid separation that is provided on the communication channel and does not transmit liquid but transmits gas Department, and
A detection unit capable of detecting a reaction between the gas introduced into the communication channel from the gas-liquid separation unit and the liquid in the communication channel is provided .

Furthermore, a liquid storage part communicating with the pump part can be provided.
It is preferable that the pump part, the diameter-enlarging channel, the diameter-reducing channel, and the communication channel are formed in the same substrate.

Before Symbol detection unit, a structure including a working electrode disposed near the gas-liquid separator a said communication passage, a counter electrode which are provided spaced apart from the working electrode to said communication passage be able to.

  In the circulation liquid feeding device of the present invention, a circulation closed circuit is formed in which a pump unit, an enlarged diameter flow path, a reduced diameter flow path, and a communication flow path are connected. When the volume of the part is changed, it is possible to generate a flow in which the liquid flows into the pump part from the enlarged diameter channel and the liquid in the pump part flows out from the reduced diameter channel. Since the fluid in the buffer unit is compressed and pumped in accordance with the volume change of the pump unit, the liquid in the circulation closed circuit can flow even if the liquid is incompressible. Therefore, according to the circulation liquid feeding device of the present invention, the internal liquid can be circulated smoothly even if a narrow flow path is included in a part of the circulation closed circuit.

  Further, according to the gas detection device of the present invention, the internal liquid can be easily circulated even if the volume of the flow path serving as the reaction region is reduced and the distance between the gas-liquid separation part and the working electrode is reduced. Therefore, the internal liquid replenishment and refresh functions can be obtained in the reaction region. Therefore, it is possible to prevent the internal liquid from being dried in the vicinity of the gas-liquid separation unit, and it is possible to suppress an increase in the concentration of the internal liquid in the reaction region, thereby preventing the internal liquid and the electrode surface from being altered. Therefore, a small and high-performance gas detection device can be realized.

1 and 2 schematically show an embodiment of the gas detection device of the present invention. FIG. 1 is a plan view and FIG. 2 is a cross-sectional view taken along line AA in FIG.
In the figure, reference numeral 1 denotes a plate-like base body, in which a circulation closed circuit composed of a pump section 11, an enlarged diameter flow path 12, a reduced diameter flow path 13, and a communication flow path 14 is formed. The communication channel 14 includes a first wide portion 14a adjacent to the enlarged diameter channel 12, a second wide portion 14c adjacent to the reduced diameter channel 13, and a reaction portion 14b provided therebetween. They are connected via intermediate flow paths 14d and 14e that are narrower than these. A buffer unit 30 is provided in the reaction unit 14b. In addition, a piezoelectric element 21 as a driving device is provided on the pump unit 11, and the piezoelectric element 21 is electrically connected to a voltage applying unit (not shown).

The substrate 1 is formed by liquid-tightly laminating and integrating a film-like member capable of forming a fine opening on one surface of a plate-like member capable of forming a flow path. As the plate member, for example, a glass plate 2 is preferably used, and as the film member, for example, a silicon (Si) film 3 is preferably used.
In the present embodiment, the glass plate 2 has a thickness of 1 mm, the silicon film 3 has a thickness of 0.1 mm (100 μm), and the substrate 1 has a length (vertical) of 20 mm in the X direction and a Y direction. It has a length (horizontal) of 15 mm and a thickness of 1.1 mm.

The pump unit 11 is composed of a space surrounded by a substantially circular recess 11a formed on one side of the glass plate 2 and a silicon film 3 that closes the opening of the recess 11a. The space can store a liquid, and the volume is changed when the silicon film 3 is pressed and bent. A through hole 11b that penetrates to the other surface side of the glass plate 2 is provided on the bottom surface of the recess 11a. Although not shown, a liquid storage tank (liquid storage part) is liquid-tightly connected to the through-hole 11b through an open / close valve.
In the present embodiment, the depth of the concave portion 11a of the pump portion 11 is 0.9 mm, and the diameter when viewed in plan is about 7.0 mm.

Each of the enlarged diameter flow path 12 and the reduced diameter flow path 13 is composed of a space surrounded by a concave groove formed on one surface side of the glass plate 2 and a silicon film 3 closing the opening of the concave groove.
The enlarged diameter flow path 12 is substantially linear when viewed from above, and has one end connected to the pump section 11 and the other end connected to the first wide portion 14 a of the communication flow path 14. The diameter of the diameter-enlarged flow path 12 is constant and the width gradually increases toward the pump part 11, and thus the cross-sectional area is formed so as to gradually increase toward the pump part 11. The depth of the enlarged diameter flow path 12 is smaller (shallow) than the depth of the pump part 11.
The reduced-diameter channel 13 is substantially linear when viewed from above, and has one end connected to the pump unit 11 and the other end connected to the second wide portion 14c. The depth of the reduced diameter flow path 13 is constant and the width is gradually reduced toward the pump part 11, and thus the cross-sectional area is formed to be gradually reduced toward the pump part 11. The depth of the reduced diameter channel 13 is formed smaller (shallow) than the depth of the pump unit 11.
The diameter-enlarging channel 12, the diameter-reducing channel 13, and the pump unit 11 constitute a so-called diffuser pump. That is, when pumping is performed by changing the volume of the pump unit 11 in a state where the pump unit 11 is filled with liquid, a pressure difference is generated by the two diffusers (the expanded channel 12 and the reduced channel 13). Thus, the liquid flows into the pump section 11 from the enlarged diameter flow path 12 and the liquid in the pump section 11 flows out from the reduced diameter flow path 13. Each dimension in the enlarged diameter flow path 12 and the reduced diameter flow path 13 is designed so that a preferable pressure difference is obtained between the two flow paths.
For example, in this embodiment, the diameter-enlarged flow path 12 and the diameter-reduced flow path 13 have a depth of 0.8 mm and a length of 3.0 mm, and the widths at both ends of the diameter-enlarged flow path 12 are 0.88 mm and 0.5 mm, respectively. The widths at both ends of the reduced diameter channel were 0.13 mm and 0.5 mm, respectively.

The communication channel 14 is formed of a space surrounded by a groove formed on one surface side of the glass plate 2 and the silicon film 3 that closes the opening of the groove.
A reaction portion 14b is provided at the central portion in the direction along the flow path length of the communication flow path 14. The first wide portion 14a and the intermediate flow path 14d downstream of the reaction section 14b and the second wide section 14c and the intermediate flow path 14e upstream of the reaction section 14b are substantially symmetrical. It is configured.
The first wide portion 14a, the intermediate flow path 14d, the reaction section 14b, the intermediate flow path 14e, and the second wide width section 14c are all formed to have the same depth as the enlarged diameter flow path 12 and the reduced diameter flow path 13. It is 0.8 mm.
In the present embodiment, the length of the first wide portion 14a and the second wide portion 14c in the direction along the flow path length is 3.0 mm, and the width in the direction perpendicular thereto is 1.0 mm at the largest portion. Is formed. Further, the length of the intermediate flow paths 14d and 14e in the direction along the flow path length is 4.0 mm, and the width in the direction perpendicular thereto is 0.5 mm, which is substantially constant. ,

The reaction unit 14b is provided with a buffer unit 30 that can trap a compressible fluid. That is, a through hole 31 that penetrates to the other surface side of the glass plate 2 is provided in a part of the bottom surface of the concave groove forming the reaction portion 14b, and the through hole 31 is airtightly opened and closed on the other surface of the glass plate 2. A freely closing valve 32 is bonded and fixed, and a compressible fluid is accommodated in the through hole 31 and the valve 32. The valve 32 includes a valve main body 32a having a cylindrical shape and a thread formed on the inner surface thereof, and a plug body 32b that is screwed into the valve main body 32a. The valve body 32a is preferably a female screw, and the plug body 32b is preferably a male screw in order to ensure airtightness.
When a liquid is filled in the circulation closed circuit including the reaction unit 14b, a pump can be used if a compressible fluid is hermetically accommodated in a space formed by the inside of the valve 32 and the inside of the through hole 31 in the buffer unit 30. As the volume of the part 11 changes, the gas in the buffer part 30 is pumped, so that the liquid can be circulated in the circulation closed circuit.
The compressible fluid trapped in the buffer unit 30 is preferably a gas having low reactivity with the liquid in the circulation circuit, and for example, air, nitrogen, argon or the like is used.
The buffer unit 30 is preferably configured so that the fluid inside thereof does not flow out into the circulation circuit. When the fluid has a lower specific gravity than the liquid in the circulation circuit, the buffer unit 30 is located above the reaction unit 14b. It is preferable that the liquid level in the circulation closed circuit is positioned in the middle of the through hole 31 of the buffer unit 30.
In the present embodiment, the inner diameter of the through hole 31 of the buffer unit 30 is formed to be 1.0 mm, and the volume of the fluid trapped in the buffer unit 30 is preferably about 0.5 to 1.0 ml.

In the reaction part 14b, a part of the silicon film 3 is provided with a gas-liquid separation part that does not transmit liquid but transmits gas. In the present embodiment, an opening 5 having a substantially rectangular shape in plan view is formed in the silicon film 3 as a gas-liquid separator.
3 to 5 are enlarged views of the gas-liquid separation part in the present embodiment. FIG. 3 is a plan view of the opening 5. FIG. 4 is a cross-sectional view taken along line AA in FIG. 5 is a cross-sectional view taken along line BB in FIG. For convenience, reference numeral 3 a is the front surface of the silicon film 3, and 3 b is the back surface of the silicon film 3.
The inner wall surfaces 5a and 5c of the opening 5 are inclined with respect to the thickness direction (Z direction in the figure) of the silicon film 3 so that the opening area expands toward the surface side of the silicon film 3. A slit hole 5b having a line shape in plan view is formed in the lowermost part (bottom) on the back side of the film 3.
Here, the opening area of the opening 5 refers to the area of a portion that becomes a hole when the opening 5 is cut in a cross section perpendicular to the thickness direction (Z direction) of the silicon film 3.
That is, as shown in FIG. 4, the cross-sectional shape perpendicular to the length direction (Y direction in the drawing) of the opening 5 is formed in a substantially V shape. Also, the inner wall surfaces 5c at both ends in the length direction of the opening 5 are also inclined with respect to the Z direction, and the length of the opening 5 in the Y direction is the smallest in the lowermost (bottom) slit hole 5b. From there, it gradually expands toward the surface 3a side.

The inner wall surfaces 5a and 5c of the opening 5 are subjected to water repellent treatment. Specifically, a thin film made of a water repellent is provided on the inner wall surfaces 5a and 5c, and the static contact angle of the inner wall surfaces 5a and 5c with respect to a predetermined liquid is within a predetermined range. The static contact angles of the inner wall surfaces 5a and 5c are designed in a range where a suitable water pressure resistance can be obtained at the opening 5.
That is, if the water pressure resistance in the opening 5 is high to some extent, the liquid does not flow out from the opening 5 while the liquid is filled on the back surface 3b side of the silicon film 3, and a gas-liquid separation function is obtained. The water pressure resistance in the opening 5 changes according to the surface tension of the liquid, the size of the slit hole 5b (the length in the Y direction and the width in the X direction) of the opening 5, and the liquid and the inner wall surfaces 5a, 5c. The contact angle can be controlled. The contact angle between the liquid and the inner wall surfaces 5a and 5c can be controlled by the type of water repellent film formed on the inner wall surfaces 5a and 5c.
The water repellent treatment of the inner wall surfaces 5a and 5c is sufficient if at least the periphery of the slit hole 5b of the opening 5 is water repellent, but the entire inner wall surfaces 5a and 5c of the opening 5 are subjected to water repellent treatment. It is preferable. Further, the surface 3a of the silicon film 3 following the inner wall surfaces 5a and 5c may be subjected to water repellent treatment. On the other hand, it is preferable that the back surface 3b of the silicon film 3 that is in contact with the liquid is hydrophilic.

In order to obtain a gas-liquid separation function while circulating the internal liquid, the water pressure resistance in the opening 5 is preferably 20 kPa or more.
The size of the opening 5 only needs to be within a range in which a preferable water pressure resistance can be obtained. For example, in this embodiment, the length in the Y direction of the slit hole 5b in the back surface 3b of the silicon film 3 is 2 mm and the X direction. Is formed to have a width of 1 to 5 μm.
The inclination angle of the inner wall surfaces 5a and 5c of the opening 5 with respect to the Z direction is determined by the etching conditions (etching rate). Therefore, the length in the Y direction and the width in the X direction of the opening 5 on the surface 3 a of the silicon film 3 are set to a desired size at the bottom of the opening 5 from the inclination angle determined by the etching conditions and the thickness of the silicon film 3. The slit hole 5b is designed to be formed.
The static contact angle between the liquid and the inner wall surfaces 5a and 5c may be within a range in which a preferable water pressure resistance can be obtained. For example, in the present embodiment, the static contact angle with distilled water is formed on the inner wall surface 5a of the opening 5. A layer having a thickness of about 1 μm made of a water repellent with a target contact angle of 156 ° is formed, and the water pressure resistance against distilled water in this opening 5 is about 20 kPa.

The working electrode 7 is provided in the vicinity of the gas-liquid separation part (opening part 5) on the bottom surface of the concave groove constituting the reaction part 14b.
The working electrode 7 only needs to be configured so as to be in contact with the liquid in the flow path and to be electrically connected to a device provided outside the base 1, and the shape, material, and the like are not limited.
In this embodiment, as the working electrode 7, a film-like platinum electrode is provided on the bottom surface of the concave groove by vapor deposition, and the conductive wire 8 connected to the working electrode 7 penetrates the glass plate 2 and is outside the substrate 1. Has been derived.

In addition, an electrode as the counter electrode 9 is provided on the bottom surface of the groove forming the first wide portion 14a. The material and shape of the counter electrode 9 are not particularly limited. For example, the counter electrode 9 may have the same configuration as the working electrode 8.
In addition, although it is not essential, a reference electrode and a flow meter may be provided in the circulation closed circuit, and for example, these may be provided in the second wide portion 14b.

  The piezoelectric element 21 is fixed on the silicon film 3 constituting the pump unit 11. The piezoelectric element 21 has a film shape and is formed of a material having piezoelectricity such as PZT (lead zirconate titanate). Then, by periodically changing the voltage applied to the piezoelectric element 21 from a voltage applying means (not shown), the piezoelectric element 21 is vibrated, and the silicon film 3 is periodically pressed and bent by the vibration. Thus, the volume of the pump unit 11 can be changed periodically.

The gas detection device of the present embodiment can be manufactured roughly as follows.
That is, first, the glass plate 2 is formed with recesses and grooves corresponding to the pump part 11, the enlarged diameter flow path 12, the reduced diameter flow path 13, the communication flow path 14 and the like, and further the working electrode 7, the counter electrode 9 and the like. Provide. The processing for forming the flow path in the glass plate 2 can be performed by a known method such as sand blasting or ultrasonic processing. In these methods, the shape and depth of the recesses and grooves can be freely controlled.
Separately from this, an opening 5 is formed on the surface of the silicon film 3, water-repellent treatment is performed to form a gas-liquid separation portion, and a piezoelectric element 21 is provided on the surface.
And the gas detection apparatus is obtained by carrying out lamination | stacking integration of the surface in which the ditch | groove etc. of these glass plates 2, etc. were formed, and the back surface of the silicon film 3 by anodic bonding. The valve 32 of the buffer unit 30 and the liquid storage tank (not shown) may be provided before the anodic bonding of the glass plate 2 and the silicon film 3 or may be provided after.
The anodic bonding can be performed by a known method. That is, when the silicon film 3 and the glass plate 2 are stacked and heated to about 300 to 400 ° C. and a voltage of about 500 V to 1 kV is applied, a large electrostatic attraction is generated between the silicon film 3 and the glass plate 2. However, the two are chemically bonded at these interfaces.

In the method of forming the opening 5 in the silicon film 3, first, crystal anisotropic etching by wet etching is performed on the silicon film 3 to form a groove having a hole 5b.
When crystal anisotropic etching is performed from the surface 3a side of the silicon film 3, the inner wall surfaces 5a and 5c are formed to be inclined with respect to the thickness direction (Z direction) of the silicon film 3, and the etching time is suitably set. For example, a slit hole 5b is formed in which the inner wall surface reaches the bottom of the silicon film 3 and penetrates to the back surface 3b side.
In the slit hole 5b, the length in the Y direction and the width in the X direction adjust the etching mask size used during crystal anisotropic etching when the thickness of the silicon film 3 and the etching conditions (etching rate) are determined. Can be controlled.
As an etching mask, an SiO ₂ film formed on the surface 3a of the silicon film 3 and patterned by a photolithography method can be used. ,

The water repellent treatment of the inner wall surfaces 5a and 5c is preferably performed in a state where a peelable adhesive sheet is in close contact with the back surface 3b of the silicon film 3 in advance. By doing so, it is possible to prevent the water repellent treatment from reaching the back surface 3b of the silicon film 3, which is preferable for making the back surface 3b hydrophilic.
Then, a liquid water repellent is coated on the surface 3a of the silicon film 3 by using an appropriate coating method such as a spray method, a coating method, or a dipping method. At this time, it is preferable to coat a water repellent on at least the entire inner wall surfaces 5a and 5c of the opening 5. More preferably, the entire surface 3a of the silicon film 3 is coated.
Moreover, it is preferable to apply vibration to the coated water repellent by ultrasonic waves to remove bubbles in the water repellent.
Thereafter, the coated water repellent is dried. The drying conditions are set such that the solvent in the coated water repellent is removed and a thin film made of the water repellent is formed.

Here, if air bubbles are present in the coated water repellent during drying, the water repellent treatment tends to be insufficient in the vicinity of the air bubbles. In particular, if air bubbles are likely to stay in the lowermost part of the opening 5 and the water-repellent treatment around the slit hole 5b becomes insufficient, the water pressure resistance cannot be obtained as designed. This can be prevented by removing bubbles in the water repellent using ultrasonic waves.
The water repellent used in the water repellent treatment has a desired contact angle after the treatment, good wettability to the surface to be coated, and a film thickness that can be coated on the inner wall surface of the minute opening 5. Those are preferred. Specifically, those containing fluorine as a main component are suitable, and specific examples include HIRECX1 (trade name; manufactured by NTT-Advanced Technology). The drying condition of the water repellent is preferably, for example, in the range of about 50 to 60 ° C. and about 60 to 120 minutes.

  For example, when chlorine gas is detected using the gas detection device of the present embodiment, the flow path in the substrate 1 is first filled with an alkali bromide solution as an internal solution. Specifically, the plug 32b of the buffer unit 30 is removed and the valve body 32a is used as an air vent hole to supply internal liquid from the liquid storage tank to the pump unit 11 through the through hole 11b. The supply amount of the internal liquid is such that the inside of the pump part 11 is completely filled with the internal liquid, the flow path leading from the through hole 11b of the pump part 11 to the liquid storage tank is also filled with the internal liquid, and the penetration of the buffer part 30 It is preferable to set so that the water surface is located in the middle of the hole 31. Then, the valve between the through hole 11 b of the pump unit 11 and the liquid storage tank is closed, and the plug body 32 b is closed in a state where the gas is contained in the buffer unit 30.

After supplying the internal liquid, when a constant voltage is applied between the working electrode 7 and the counter electrode 9 so that the working electrode 7 becomes a cathode (cathode), hydrogen is generated and polarized in the working electrode 7.
When chlorine gas permeates into the flow path from the opening 5 having a gas-liquid separation function, the reaction between the chlorine gas and the internal liquid occurs in the reaction section 14b. As a result, the polarization is released and a current flows between the working electrode 7 and the counter electrode 9, so that chlorine gas can be detected.

On the other hand, the internal liquid can be circulated by vibrating the piezoelectric element 21 to change the volume of the pump unit 11. The internal liquid may be circulated continuously or intermittently. The flow rate and flow rate of the circulating liquid may be constant or may be changed with time.
The driving waveform when changing the voltage applied to the piezoelectric element 21 can be a rectangular wave or a sine wave. However, the rectangular wave is preferable for increasing the flow rate and the flow velocity. If the frequency is too large or too small, the flow rate and flow rate tend to decrease. When the driving waveform is a rectangular wave, the frequency is preferably about 300 to 400 Hz. For example, 39.7 μl / min can be achieved at a frequency of 320 Hz as the maximum value of the flow rate. When the drive waveform is a sine wave, the frequency is preferably about 200 to 300 Hz. For example, as the maximum value of the flow rate, 14.9 μl / min can be achieved at a frequency of 250 Hz.

In the present embodiment, the enlarged diameter flow path 12, the reduced diameter flow path 13, and the pump unit 11 constitute a diffuser pump, and the expanded diameter flow path 12 and the reduced diameter flow path 13 are connected by the communication flow path 14, and further the gas Since the buffer part 30 that can store the air in a gas-tight manner is provided, even if the gas trapped in the buffer part 30 is pumped and the inside of the circulation closed circuit is filled with the incompressible liquid, the liquid can flow and circulate. .
According to the present embodiment, in the reaction part 14b, the working electrode 7 is provided in the vicinity of the gas-liquid separation part (opening part 5), and the counter electrode 9 is provided in the first wide part 14a. And a quick and stable response can be obtained.
Moreover, since the reaction part 14b is provided in the circulation channel, the liquid in the reaction part 14b can be circulated continuously or intermittently. Therefore, even if the distance between the gas-liquid separation part (opening part 5) and the working electrode 7 is small, the internal liquid in contact with the gas-liquid separation part (opening part 5) is dried by circulating the internal liquid in contact therewith. Can be prevented. Further, even when the internal liquid or the working electrode 7 is likely to be deteriorated due to an increase in concentration of the measurement target component or interference component in the internal liquid, it is possible to prevent such deterioration by circulating the internal liquid. Therefore, even if the volume of the reaction part 14b is reduced and the distance between the gas-liquid separation part (opening part 5) and the working electrode 7 is reduced, high sensor performance can be obtained. It can be secured and contributes to the miniaturization of the device.
In this embodiment, the distance between the gas-liquid separation part (opening part 5) and the working electrode 7 can be reduced to about 0.05 mm by changing the depth of the reaction part 14b. The upper limit of the distance between the gas-liquid separation part (opening part 5) and the working electrode 7 is not particularly limited, but is preferably about 0.2 mm or less in order to secure a quick and stable response, and more preferably. Is 0.1 μm or less.

Moreover, in this embodiment, since the liquid storage tank (not shown) is connected with the pump part 11, especially when an internal liquid is easy to dry, the density | concentration of the measuring object component and interference component in an internal liquid When it is easy to rise, the internal liquid can be replenished from the storage tank to the circulation flow path 14 via the pump unit 11, so that deterioration of the sensor function can be prevented.
In the present embodiment, a circulation circuit including the pump unit 1, the gas-liquid separation unit (opening 5), and the detection device (working electrode 7 and counter electrode 9) is formed inside one base body 1. It is very compact.

  Furthermore, in the apparatus of the present embodiment, the first wide portion 14a and the second wide portion 14c are provided in the circulation flow path 14, so that the liquid in the flow path is difficult to stagnate. Moreover, since the 1st wide part 14a and the 2nd wide part 14c are suitable for providing components, such as an electrode and a flow meter, in space, these components can be easily provided in a flow path. In particular, in this embodiment, the working electrode 7 is provided in the reaction part 14b, and the counter electrode 9 is provided in the first wide part 14a. Therefore, the distance between these electrodes is short, and bubbles are less likely to enter between the electrodes. ing.

Moreover, in this embodiment, since the flow path is formed in the glass plate 2, it is possible to observe the inside of a flow path visually.
In this embodiment, the working electrode and the counter electrode are provided apart from each other in the flow path, and the coulometric detection method is adopted.However, the gas detection method is not limited to this, and for example, the light emitting unit It can also be configured to detect the gas by an optical detection method by providing the light receiving portion apart.
Further, in the present embodiment, as the gas-liquid separation part, the opening 5 having the slit hole 5b is formed in the silicon film 3, and the inner wall surfaces 5a and 5c are subjected to the water repellent treatment. Instead, for example, an appropriate gas-liquid separation membrane that does not transmit liquid but transmits gas, such as a porous membrane obtained by stretching polytetrafluoroethylene or the like, can be used. In particular, the silicon film 3 is preferable because it can be chemically bonded to the glass plate 2 and high sealing properties can be obtained. The glass plate 2 is preferable because it has excellent chemical resistance.

It is a top view which shows one Embodiment of the gas detection apparatus which concerns on this invention. It is sectional drawing which follows the AA line in FIG. It is a top view which shows the example of the gas-liquid separation part in embodiment which concerns on this invention. It is sectional drawing which follows the AA line in FIG. It is sectional drawing which follows the BB line in FIG.

Explanation of symbols

1 Substrate 2 Glass plate 3 Silicon film 5 Opening (gas-liquid separation part)
7 Working electrode (detector)
9 Counter electrode (detector)
DESCRIPTION OF SYMBOLS 11 Pump part 12 Diameter expansion flow path 13 Reduction diameter flow path 14 Connection flow path 21 Piezoelectric element (drive device)
30 Buffer section

Claims (4)

A pump unit that can store liquid and has a variable volume, is connected to the pump unit, has a diameter-enlarged flow path whose cross-sectional area expands toward the pump unit, is connected to the pump unit, and has a cross-sectional area toward the pump unit. A reduced diameter channel to be reduced, a communication channel that communicates the expanded diameter channel and the reduced diameter channel, a buffer unit that communicates with the communication channel and stores a compressible fluid, and a volume of the pump unit A circulating liquid feeding device comprising a drive device capable of changing
A gas-liquid separator that is provided on the communication channel and does not transmit liquid but transmits gas; and
A gas detection apparatus comprising a detection unit capable of detecting a reaction between a gas introduced from the gas-liquid separation unit into the communication channel and a liquid in the communication channel . The gas detection device according to claim 1, further comprising a liquid storage unit communicating with the pump unit. The gas detection device according to claim 1, wherein the pump unit, the diameter-enlarging channel, the diameter-reducing channel, and the communication channel are formed in the same base. The detection unit includes a working electrode provided in the communication channel and in the vicinity of the gas-liquid separation unit, and a counter electrode provided in the communication channel and spaced apart from the working electrode . The gas detection device according to any one of 3 .

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