JP6429193B2 - Alcohol sensor - Google Patents

Description

  The present invention relates to an alcohol sensor technology, and more particularly to an alcohol sensor in which the influence of a detection interference gas such as CO is reduced.

  Alcohol gas has the property that a chemical reaction occurs using Pt black as a catalyst to generate an electric current. Conventionally, in order to measure the alcohol concentration in a detection target gas such as human exhalation, the detection target gas is brought into contact with Pt black, the generated current is passed through a resistance element, and the voltage is measured. An alcohol sensor that measures the concentration of alcohol contained in gas is used.

However, since CO gas also has a property of chemically reacting with Pt black when it comes into contact with Pt black, if the detection target gas contains CO together with alcohol, the measured value of the alcohol concentration becomes inaccurate. .
In addition, since the current generated by the chemical reaction of the alcohol is very small, the measured value of the alcohol concentration becomes inaccurate if the resistance in the measurement circuit including the electrode containing Pt black is large.

  As described in the following document, trial and error for accurately determining the alcohol concentration is performed, but it is difficult to manufacture at low cost.

JP 2009-229285 A JP 2008-510629 A

  SUMMARY OF THE INVENTION In order to solve the above-described problems of the prior art, an object of the present invention is to provide an alcohol sensor that can be easily manufactured and can obtain an accurate measurement value.

In order to solve the above problems, the present invention has a vent-side container, a liquid reservoir-side container, and a film-like alcohol detection sheet, and the alcohol detection sheet has a surface on the first base film, A film-like working portion in which a working electrode containing platinum black is formed, a film-like working portion in which a counter electrode containing platinum black is formed on the surface of the second base film, and a cation to pass therethrough. A cation permeable membrane, and provided on the inner peripheral surface of the vent-side container is a vent-side pressing portion that protrudes toward the inside of the vent-side container. Is provided with a liquid reservoir-side pressing portion that protrudes toward the inside of the liquid reservoir-side container, and a vent-side opening that is a container opening of the vent-side container is directed to the working electrode. A reservoir side opening, which is a container opening of the container, is directed to the counter electrode, and the ventilation side push The alcohol detection sheet is composed of the vent-side container and the liquid-side container in a state where at least a part of the edge portion of the alcohol-detection sheet is sandwiched and pressed by the liquid reservoir-side pressing part. The alcohol detection sheet contains a non-volatile acid solution, and the inside of the closed container is located between the bottom plate of the vent-side container and the alcohol detection sheet by the alcohol detection sheet. Divided into a detection space and a liquid storage space between the bottom plate of the liquid storage side container and the alcohol detection sheet, the closed container is connected to the outside of the closed container and the detection space, respectively. And a discharge port, and when a measurement target gas containing alcohol is introduced into the detection space from the introduction port and discharged from the discharge port, the measurement target gas is It said alcohol being closed reacts with the working electrode, between the counter electrode and the working electrode, an alcohol sensor that generates a current corresponding to the alcohol concentration of the measurement target gas.
The present invention is an alcohol sensor, wherein a bottom plate of the vent-side container is provided with a container-side projection protruding toward the vent-side opening, and the bottom plate of the liquid-side container has the liquid-side opening. A liquid reservoir-side protrusion protruding toward the surface is provided, and a central portion including the center of the alcohol detection sheet is an alcohol sensor sandwiched and pressed between the container-side protrusion and the liquid reservoir-side protrusion.
The present invention is an alcohol sensor, wherein the nonvolatile acid solution is present between an outer peripheral surface of the alcohol detection sheet and an inner peripheral surface of the sealed container.
The present invention is an alcohol sensor, wherein the cation permeable membrane is a perfluorosulfonic acid-polytetrafluoroethylene membrane.
This invention is an alcohol sensor, Comprising: Said 1st base film and said 2nd base film are alcohol sensors formed by resin powder being sintered in the film form.
The present invention is an alcohol sensor, wherein the nonvolatile acid solution contains a surfactant.
The present invention is an alcohol sensor, wherein the working electrode is formed by pressing platinum black on a surface of the first base film, and the counter electrode has platinum black on a surface of the second base film. It is an alcohol sensor formed by being pressed.
The present invention is a film-like alcohol detection sheet provided with a film-like action part, a film-like pair part, and a cation permeable membrane, wherein the action part is obtained by sintering a resin powder into a film form. And a first base film whose back surface is in contact with one surface of the cation permeable membrane, and a working electrode containing platinum black pressed and fixed to the surface of the first base film. The counter part is formed by sintering a resin powder into a film, and a back surface of the second base film in contact with a surface opposite to the one surface of the cation permeable membrane; A counter electrode containing platinum black pressed and fixed to the surface of the second base film, and the cation permeable membrane is a perfluorosulfonic acid-polytetrafluoroethylene membrane, Non-volatile acid solution on the second base film Once closed, the hydrogen ions generated by chemical reaction of the alcohol in contact with the working electrode, passes through the cation permeable membrane is an alcohol detection sheet to reach the counter electrode.
The present invention includes a vent-side container, a liquid reservoir-side container, and the above-described alcohol detection sheet containing the non-volatile acid solution, and the vent-side container is provided on an inner peripheral surface of the vent-side container. A vent-side pressing portion that protrudes toward the inside of the liquid reservoir-side container, and a liquid reservoir-side pressing portion that protrudes toward the inside of the liquid reservoir-side container is provided on the inner peripheral surface of the liquid reservoir-side container. A vent side opening, which is a container opening of the vent side container, is directed to the working electrode, a liquid reservoir side opening, which is a container opening of the liquid reservoir side container, is directed to the counter electrode, and the vent side pressing portion and the liquid reservoir In the state where at least a part of the edge portion of the alcohol detection sheet is sandwiched and pressed by the side pressing portion, the alcohol detection sheet is in an airtight container constituted by the vent side container and the liquid reservoir side container. The inside of the sealed container is placed in the alcohol test. The sheet is divided into a detection space between the bottom plate of the vent-side container and the alcohol detection sheet and a liquid storage space between the bottom plate of the liquid-side container and the alcohol detection sheet. Is provided with an inlet and an outlet for connecting the outside of the hermetic container and the detection space, respectively, and a gas to be measured containing alcohol is introduced into the detection space from the inlet and discharged from the outlet. Then, the alcohol contained in the measurement object gas reacts with the working electrode, and generates an electric current according to the alcohol concentration of the measurement object gas between the working electrode and the counter electrode. is there.
The present invention is an alcohol sensor, wherein a bottom plate of the vent-side container is provided with a container-side projection protruding toward the vent-side opening, and the bottom plate of the liquid-side container has the liquid-side opening. A liquid reservoir-side protrusion protruding toward the surface is provided, and a central portion including the center of the alcohol detection sheet is an alcohol sensor sandwiched and pressed between the vent-side protrusion and the liquid reservoir-side protrusion.
The present invention is an alcohol sensor, wherein the nonvolatile acid solution is present between an outer peripheral surface of the alcohol detection sheet and an inner peripheral surface of the sealed container.

Accurate alcohol concentration can be easily measured.
Also, the alcohol sensor can be easily manufactured.

(a)-(g): The figure for demonstrating the manufacturing procedure of the alcohol detection sheet | seat of this invention. The figure for demonstrating the aeration side container and the liquid reservoir side container of a 1st example Diagram for explaining sealed container The figure for demonstrating the assembly procedure of the alcohol sensor of the 1st example of this invention. The alcohol sensor of the first example of the present invention corresponding to the cross-sectional view taken along line AA in FIG. The alcohol sensor of the first example of the present invention corresponding to the sectional view taken along the line BB in FIG. Plan view of the alcohol sensor of the present invention The figure for demonstrating the aeration side container and liquid reservoir side container of a 2nd example The figure for demonstrating the assembly procedure of the alcohol sensor of the 2nd example of this invention The alcohol sensor of the second example of the present invention

<Alcohol detection sheet>
Reference numerals 2 and 3 in FIG. 5 and FIG. 10 are alcohol sensors of the first and second examples of the present invention, each having a sealed container 21 and an alcohol detection sheet 10 arranged inside the sealed container 21. Yes.

First, the manufacturing process of the alcohol detection sheet 10 will be described. 1 (a) to 1 (g), reference numeral 11 in FIG. 1 (a) indicates a film-like base film formed by firing resin powder. On the surface of the base film 11, a platinum black paste in which a platinum black powder is dispersed in a solvent is applied to form a paste layer 18. In this example, the platinum black paste has platinum black powder dispersed in a mixture of water and 2-propanol (isopropyl alcohol), and does not contain a binder.
Moreover, the base film 11 is a film-like sintered body of polyethylene powder, and has water absorption and water retention.

  Next, the base film 11 on which the paste layer 18 is formed is carried into a drying apparatus, dried at a temperature lower than 100 ° C. to evaporate the solvent, and as shown in FIG. The layer 18 is changed to a platinum black layer 19 containing no solvent.

  The base film 11 on which the platinum black layer 19 is formed is disposed on a base 31 as shown in FIG. 1C, and the pressing device 37 is brought into contact with the platinum black layer 19 so that the pressing device 37 The platinum black layer 19 is pressed with a constant pressure in a direction in which the plate 37 and the table 31 approach each other.

  When the platinum black layer 19 is pressed, the platinum black particles forming the platinum black layer 19 sink into the base film 11, and the platinum black particles are fixed to the base film 11, as shown in FIG. Moreover, the raw fabric 16 in which the platinum black layer 19 is made into the electrode layer 12 is obtained.

  The pressing condition is, for example, a pressure of 1 MPa for 10 minutes, and the pressing may be performed at room temperature (here, 23 ° C.), but the base film 11 and the platinum black layer 19 are heated during pressing. However, the temperature may be raised to room temperature or higher in the range of 100 ° C. or lower.

Next, the electrode layer 12 and the base film 11 on which the electrode layer 12 is formed are cut together, and, as shown in FIG. Form.
Of the plurality of small pieces 17, a small piece 17 used as an action part and a small piece 17 used as a counter part are selected, the electrode layer 12 of the small piece 17 of the action part is used as the working electrode 12a, and the base material on which the working electrode 12a is arranged When the film 11 is the first base film 11a, as shown in FIG. 1 (f), the first base film 11a is brought into contact with one surface of the cation permeable membrane 14 having the same shape and the same area as the small piece 17. Then, the action part 5 a is arranged on the cation permeable membrane 14.

  Next, assuming that the electrode layer 12 of the pair of small pieces 17 is the counter electrode 12b and the base film 11 on which the counter electrode 12b is disposed is the second base film 11b, as shown in FIG. When the second base film 11b is brought into contact with the surface on the opposite side of the cation permeable membrane 14 on which the action part 5a is arranged, the alcohol detection sheet 10 is obtained.

In the above example, the action part 5a and the pair part 5b are obtained from the same original fabric 16, but the action part 5a and the pair part 5b can be obtained from different original fabrics, and the action part 5a and the pair part 5b can be obtained. The film thickness and material of the first and second base films 11a and 11b can be made different, and the density and film thickness of platinum black of the working electrode 12a and the counter electrode 12b can be made different.
Note that the working electrode 12a and the counter electrode 12b have conductivity in both the film thickness direction and the spreading direction of the thin film.

で表されるポリテトラフルオロエチレン−パーフルオロスルホン酸共重合体（［ｔｅｔｒａｆｌｕｏｒｏｅｔｈｙｌｅｎｅとｐｅｒｆｌｕｏｒｏ［２−（ｆｌｕｏｒｏｓｕｌｆｏｎｙｌｅｔｈｏｘｙ）ｐｒｏｐｙｌｖｉｎｙｌ ｅｔｈｅｒ］の共重合体）の膜であり、パーフルオロスルホン酸−ポリテトラフルオロエチレン膜とも呼ばれている。ここでは、Ｎａｆｉｏｎ(デュポン(株)製、登録番号第１１７４２５２号の登録商標)を用いた。 The cation permeable membrane 14 has the following structural formula:

A polytetrafluoroethylene-perfluorosulfonic acid copolymer (a copolymer of [tetrafluoroethylene and perfluoro [2- (fluorosulfonyethyl) propylvinyl ether]), a perfluorosulfonic acid-polytetrafluoroethylene membrane. It is also called. Here, Nafion (registered trademark of No. 1174252, manufactured by DuPont) was used.

  In the manufacturing process of the alcohol detection sheet 10, there is no process of applying a platinum black paste on both surfaces of the cation permeable membrane 14, so that the manufacturing is easy, and the platinum black paste includes an adhesive, a binder, and the like. Since the hydrophobic component is not contained, the hydrophilicity is high.

<Alcohol sensor>
Next, with reference to FIG. 5 and FIG. 10, the alcohol sensor 2 and 3 of the 1st example and the 2nd example which have arrange | positioned the alcohol detection sheet | seat 10 inside the airtight container 21 are demonstrated.

In the first example and the second example, the sealed container 21 is composed of ventilation side containers 21a and 21c and liquid storage side containers 21b and 21d as shown in FIGS.
The assembly process will be described with the alcohol sensor 2 of the first example. As shown in FIG. 4, a vent side opening 27a that is a container opening of the vent side container 21a and a liquid reservoir side opening that is a container opening of the liquid reservoir side container 21b. 27b, and the upper ends of the side walls 32a and 32b are brought into contact with each other so that they can be fixed to each other. FIG. 3 shows the sealed container 21 when the vent-side container 21a and the liquid reservoir-side container 21b are assembled.

  The inner peripheral surface of the side wall 32a of the vent side container 21a is provided with a vent side pressing portion 33a that protrudes toward the center of the region surrounded by the side wall 32a. Similarly, the side wall 32b of the liquid reservoir side container 21b is provided. A liquid reservoir side pressing portion 33b that protrudes toward the center of the region surrounded by the side wall 32b is provided on the inner peripheral surface.

  Here, the vent-side pressing portion 33a and the liquid reservoir-side pressing portion 33b are thin annular members whose surfaces are directed to the bottom plates 31a and 31b and whose opposite surfaces are directed to the vent-side opening 27a or the liquid reservoir-side opening 27b. It is a flat plate.

  The bottom plate 31a of the vent-side container 21a is provided with a vent-side protrusion 34a that protrudes toward the vent-side opening 27a of the vent-side container 21a, and the bottom plate 31b of the reservoir-side container 21b has a liquid reservoir. A liquid reservoir side protrusion 34b protruding toward the liquid reservoir side opening 27b of the side container 21b is provided.

  The height from the bottom plate 31a of the surface facing the ventilation side opening 27a of the ventilation side pressing portion 33a and the height from the bottom plate 31a at the tip of the ventilation side protrusion 34a are lower than the height from the bottom plate 31a at the upper end of the side wall 32a. Similarly, the height from the bottom plate 31b of the surface of the liquid storage side pressing portion 33b toward the liquid storage side opening 27b and the height from the upper end of the bottom plate 31b at the front end of the liquid storage side projection 34b are the side wall 32b. The height is lower than the height from the bottom plate 31b at the upper end.

Therefore, when the upper ends of the side walls 32a and 32b are brought into contact with each other to form the sealed container 21, a certain distance T ₁ between the pressing parts is provided between the ventilation side pressing part 33a and the liquid reservoir side pressing part 33b. spaced facing each other and, with the tip of the tip and the liquid reservoir side projection 34b of the vent side projections 34a, facing each other at regular projection distance T _2.

  The surface where the ventilation side pressing part 33a and the liquid storage side pressing part 33b face each other is made parallel, and the part where the ventilation side protrusion 34a and the liquid storage side protrusion 34b face each other is made flat and parallel to each other. Yes.

Here, when the thickness of the alcohol detection sheet 10 is T ₀ , the distance between the pressing parts T ₁ <thickness T ₀ and the distance between protrusions T ₂ <thickness T ₀ are satisfied.

  The side wall 32a of the vent side container 21a is provided with a vent side wiring introduction hole 36a at a position between the vent side pressing portion 33a and the upper end of the side wall 32a. The side wall 32b of the liquid reservoir side container 21b has a side wall side. A liquid reservoir side wiring introduction hole 36b is provided at a position between the pressing portion 33b and the upper end of the side wall 32b.

  When the alcohol detection sheet 10 is disposed inside the sealed container 21, the alcohol detection sheet 10 contains a non-volatile acid solution in which a non-volatile acid is dissolved in water.

  The working electrode 12a and the counter electrode 12b of the alcohol detection sheet 10 have their surfaces exposed, and the portions near the tip of the ventilation side wiring introduction hole 36a and the liquid reservoir side wiring introduction hole 36b are the ventilation side protrusions 34a. The working electrode side connection wiring 15a and the counter electrode side connection wiring 15b are respectively inserted so as to be positioned on the upper end of the liquid or the liquid storage side protrusion 34b. The inserted state is shown in FIG.

  In this state, the vent-side container 21a directs the vent-side opening 27a toward the working electrode 12a of one alcohol detection sheet 10, and the liquid-container-side container 21b opens the liquid reservoir-side opening 27b to the counter electrode 12b of the same alcohol detection sheet 10. Place it toward the.

  The shape of the upper end of the side wall 32a of the vent-side container 21a and the shape of the upper end of the side wall 32b of the wall-side container 21b are the same size and the same shape, and the alcohol detection sheet 10 is formed on the side wall 32a of the vent-side container 21a. The shape is smaller than the shape of the upper end and the shape of the upper end of the side wall 32b of the liquid reservoir side container 21b.

  When the aeration side container 21a and the liquid reservoir side container 21b are brought close to each other, before the upper ends of the side walls 32a and 32b come into contact with each other, first, the alcohol detection sheet 10 has a portion near the outer periphery of the working electrode 12a. 33a, the portion near the outer periphery of the counter electrode 12b of the same alcohol detection sheet 10 is in contact with the liquid reservoir-side pressing portion 33b, and the portion near the outer periphery of the alcohol detection sheet 10 is the vent-side pressing portion 33a and the liquid reservoir-side pressing portion. 33b, and the central portion of the working electrode 12a is in contact with the tip of the vent-side protrusion 34a, the central portion of the counter electrode 12b is in contact with the liquid-side protrusion 34b, and the central portion of the alcohol detection sheet 10 Is sandwiched and pressed between the vent-side protrusion 34a and the liquid reservoir-side protrusion 34b.

  At that time, the portion near the ventilation side wiring introduction hole 36a and the portion near the tip of the working electrode side connection wiring 15a, the portion near the liquid reservoir side wiring introduction hole 36b and the portion near the tip of the counter electrode side connection wiring 15b are: The working electrode side connection wiring 15a is pressed together with the alcohol detection sheet 10, and the pressed part is brought into contact with the working electrode 12a, and the pressed part of the counter electrode side connection wiring 15b is brought into contact with the counter electrode 12b.

In this state, when the aeration side container 21a and the liquid reservoir side container 21b are pressed and moved in directions close to each other, they are pressed by the aeration side pressing part 33a and the liquid storage side pressing part 33b of the alcohol detection sheet 10. The portion pressed by the vent-side protrusion 34a and the liquid-side protrusion 34b is compressed and deformed, and the thickness is reduced, and is pressed by the vent-side press portion 33a and the liquid-side press portion 33b. When the thickness of the portion becomes the distance T ₁ between the pressing portions and the portion pressed by the ventilation side protrusion 34a and the liquid reservoir side protrusion 34b becomes the distance T ₂ between the protrusions, the upper ends of the side walls 32a and 32b extend over the entire circumference. And the closed container 21 in which the alcohol detection sheet 10 is disposed is formed, and the alcohol sensor 2 is obtained.

  A welding rib is arranged on one or both of the upper ends of the side walls 32a and 32b of the vent side container 21a and the liquid reservoir side container 21b, and the vent side container 21a and the liquid reservoir side container 21b are heated. The upper ends of the side walls 32a and 32b that are in contact with each other are welded to each other, and the state in which the sealed container 21 is formed is maintained even if the pressing of the vent-side container 21a and the liquid reservoir-side container 21b is terminated.

  When the sealed container 21 is formed, the working electrode side contact wiring 15a is in contact with the working electrode 12a and is electrically connected to the working electrode 12a, and the counter electrode side connecting wiring 15b is in contact with the counter electrode 12b and is connected to the counter electrode 12b. Electrically connected.

  Further, when the sealed container 21 is formed, the ring-shaped portion near the outer periphery of the alcohol detection sheet 10 has a ventilation side pressing portion 33a and a liquid reservoir side pressing portion 33b by the restoring force of the compressive deformation of the alcohol detection sheet 10. The ring-shaped portion in the vicinity of the outer periphery of the alcohol detection sheet 10 is kept in close contact with the surface of the ventilation side pressing portion 33a and the surface of the liquid storage side pressing portion 33b.

7 is a plan view of the alcohol sensor 2, FIG. 5 corresponds to a cross-sectional view taken along line AA in FIG. 7, and FIG. 6 corresponds to a cross-sectional view taken along line BB in FIG.
The upper ends and inner peripheral surfaces of the side walls 32a and 32b are circular, and the planar shape of the alcohol detection sheet 10 is also circular.

  The outer peripheral side surface of the alcohol detection sheet 10 is in contact with or close to either one or both of the side wall 32a of the vent-side container 21a and the side wall 32b of the liquid storage-side container 21b, and detects alcohol. The gap formed between the outer peripheral side surface of the sheet 10 and the side wall 32a of the ventilation side container 21a or the side wall 32b of the liquid storage side container 21b contains a non-volatile acid solution so that gas cannot pass therethrough. Yes.

  Further, the working electrode 12a and the counter electrode 12b are in contact with the ventilation side pressing portion 33a and the liquid storage side pressing portion 33b in a state containing a non-volatile acid solution, and accordingly, the alcohol detection sheet 10 and the ventilation side pressing portion are in contact with each other. Gas cannot pass through the portion where the portion 33a contacts and the portion where the alcohol detection sheet 10 and the liquid storage side pressing portion 33b contact.

  In addition, when the space between the working electrode 12a and the bottom plate 31a of the vent-side container 21a is a detection space 28, and the space between the counter electrode 12b and the bottom plate 31b of the liquid reservoir-side container 21b is a liquid reservoir space 29, the detection space 28 and the liquid storage space 29 are separated from each other, and gas cannot move between the detection space 28 and the liquid storage space 29.

  The side wall 32a of the ventilation side container 21a is provided with an introduction port 24 and a discharge port 25 at a position between the portion where the ventilation side pressing portion 33a is provided and the bottom plate 31a. Each of the introduction port 24 and the discharge port 25 can be connected to the external atmosphere of the sealed container 21.

When the measurement target gas is introduced into the detection space 28 from the introduction port 24, the measurement target gas introduced into the detection space 28 does not enter the liquid storage space 29 and come into contact with the counter electrode 12b.
The liquid reservoir space 29 is not connected to the atmosphere outside the sealed container 21 and is not connected to the detection space 28.

On the other hand, the working electrode 12a and the counter electrode 12b have a gap between the platinum black particles, and also between the first and second base films 11a and 11b and between the sintered resin particles. There is.
The cation permeable membrane 14 is a membrane that allows cations to pass therethrough. Therefore, when the gas is dissolved in the non-volatile acid solution and decomposed at the working electrode 12a or the counter electrode 12b to generate cations, the cations are generated. The cation can move in the alcohol detection sheet 10 in the film thickness direction of the alcohol detection sheet 10.
The detection space 28 has a ring shape in which a ventilation-side protrusion 34a is disposed at the center, and the liquid reservoir space 29 has a ring shape in which a liquid reservoir-side protrusion 34b is disposed in the center.

  The ventilation side container 21c of the second example is provided with a ventilation side wiring introduction hole 36c and a liquid storage side wiring introduction port 36d, and when the liquid storage side container 21d is assembled, the ventilation side wiring introduction hole 36c. The working electrode side connection wiring 15a and the counter electrode side connection wiring 15b are inserted through the liquid reservoir side wiring introduction port 36d. The inserted state is shown in FIG. In a state where the counter electrode side connection wiring 15b is bent, the alcohol detection sheet 10 is disposed between the ventilation side container 21c and the liquid reservoir side container 21d, and the alcohol detection sheet 10 is disposed on the working electrode side connection wiring 15a and the counter electrode side connection wiring 15b. Are arranged between and assembled, a second example alcohol sensor 3 (FIG. 10) having the same structure as that of the first example alcohol sensor 2 is obtained.

<Non-volatile acid solution>
The non-volatile acid contained in the non-volatile acid solution is sulfuric acid, phosphoric acid, etc., and the non-volatile acid is dissolved or diluted in water. If the concentration is too high, water will be absorbed when placed in a high humidity atmosphere. However, it is inappropriate because it increases the water content of the non-volatile acid solution and causes the non-volatile acid solution to leak from the alcohol sensors 2 and 3. If the concentration is too low, the water will dry when placed in a low-humidity atmosphere. Then, the entire base film 11a, 11b is not filled with the liquid, and conduction between the working electrode 12a and the counter electrode 12b cannot be performed.

  The rate at which the internal moisture increases is about 1/3 times the drying rate, so in the case of sulfuric acid to prevent malfunction due to drying rather than the risk of leakage, the concentration is 4 mol / L or more and 8 mol / L. The following are appropriate.

Further, when the working electrode 12a and the counter electrode 12b are formed by pressing, the surface of the working electrode 12a and the surface of the counter electrode 12b are water repellent because the electrode layer 12 is heated and pressed. Therefore, the non-volatile acid solution contains a surfactant, and when the non-volatile acid solution is applied to the alcohol detection sheet 10 or the alcohol detection sheet 10 is immersed in the non-volatile acid solution, the working electrode 12a and the counter electrode 12b, the cation permeable membrane 14, and the first and second base films 11a and 11b are infiltrated with a non-volatile acid solution, and a certain amount of non-volatile acid solution is contained in the alcohol detection sheet 10, The ion permeable membrane 14 is maintained in contact with the first and second base films 11a and 11b containing the nonvolatile acid solution.
In the surfactant, dodecylbenzenesulfonic acid having an effect as a wetting agent and preventing sensor malfunction in a low humidity environment was contained in the range of 0.5% to 5%.

<Detection procedure>
The alcohol concentration in the detection target gas sampled using the alcohol sensors 2 and 3 is measured.

  First, the working electrode side connection wiring 15 a and the counter electrode side connection wiring 15 b are connected to the measuring device 20, one end of the introduction pipe 38 is connected to the introduction port 24, and one end of the discharge pipe 39 is connected to the discharge port 25. From the other end of the tube 38, the sampled detection target gas is introduced into the detection space 28 and brought into contact with the working electrode 12a, and then discharged to the outside atmosphere of the sealed container 21 through the discharge tube 39.

When the introduced gas to be detected contains alcohol (in this case, ethyl alcohol), the alcohol is dissolved in the non-volatile acid solution and comes into contact with the working electrode 12a.
C ₂ H ₅ OH + H ₂ O → CH ₃ COOH + 4H ⁺ + 4e ⁻ (1)
To generate hydrogen ions.

The generated hydrogen ions move in the first base film 11a, pass through the cation permeable membrane 14, move in the second base film 11b, and reach the counter electrode 12b.
2O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
To generate water.

Electrons emitted by the equation (1) and absorbed by the equation (2) cause a current having a magnitude corresponding to the amount of alcohol to flow through the resistance element provided in the measuring device 20. The concentration of alcohol in the detection target gas can be obtained by measuring the magnitude of the voltage and collating it with the relationship between the alcohol concentration and the voltage value obtained in advance.
When measuring the concentration of ethyl alcohol in the exhaled breath, if the gas to be measured reaches the counter electrode 12b, the chemical reaction of the above formula (1) occurs at the counter electrode 12b, thereby hindering accurate measurement of the alcohol concentration.

  In the alcohol detection sheet 10 of the present invention, the detection space 28 and the liquid reservoir space 29 are separated by the cation permeable membrane 14, and the measurement target gas does not move from the detection space 28 to the liquid reservoir space 29. In addition, alcohol dissolved in the non-volatile acid solution is absorbed and reaches the counter electrode 12b. However, the amount of permeation is smaller than when the cation permeable membrane 14 is not used, and permeation is prevented.

Moreover, CO gas is contained in the exhaled air discharged from the smoker, and when CO in the sampling gas is dissolved in the non-volatile acid solution,
CO + H ₂ O → CO ₂ + 2H ⁺ + 2e ⁻ (3)
Since CO ions generate hydrogen ions and emit electrons, CO interferes with accurate measurement of alcohol concentration.

When the hydrophilicity of the first and second substrate films 11a and 11b is low, it has been experimentally known that the influence of CO on the output of alcohol is high, but the alcohol detection sheet 10 of the present invention is the first The second substrate films 11a and 11b are porous and have high hydrophilicity, so that the sensitivity of CO is reduced.
Therefore, the alcohol sensors 2 and 3 of the present invention have low sensitivity to CO and high sensitivity to ethyl alcohol contained in exhaled breath.

  Since the non-volatile acid solution easily absorbs water, when the alcohol detection sheet 10 is placed in a high-humidity atmosphere, the amount of water contained in the non-volatile acid solution increases and the amount that the alcohol detection sheet 10 can hold is reduced. If exceeded, a non-volatile amount of non-volatile acid solution falls.

  The liquid reservoir side container 21b has a container shape, and holds the non-volatile acid solution 30 that the alcohol detection sheet 10 can no longer hold on the bottom plate 31b as shown in FIGS.

In the above example, a Nafion film is used. However, any ion permeable film that transmits H ⁺ in a non-volatile acid solution and does not transmit CO can be used in the present invention.
Since the working electrode 12a and the counter electrode 12b do not contain a Teflon (registered trademark of EI DuPont de Nemours and Company) binder, the hydrophilicity is improved. Since the property decreases slightly, it is preferable to add a surfactant to the non-volatile acid solution.

2, 3 ... Alcohol sensor 10 ... Alcohol detection sheet 11a ... First base film 11b ... Second base film 12a ... Working electrode 12b ... Counter electrode 14 ... Cation permeable membrane 21 ... Sealed containers 21a, 21c ... vent side containers 21b, 21d ... liquid reservoir side container 24 ... inlet 25 ... discharge port 27a ... vent side opening 27b ... liquid reservoir side opening

Claims (11)

A vent-side container, a liquid reservoir-side container, and a film-like alcohol detection sheet;
In the alcohol detection sheet,
On the surface of the first base film, a film-like action part in which a working electrode containing platinum black is formed,
On the surface of the second base film, a film-like pair portion in which a counter electrode containing platinum black is formed,
A cation permeable membrane for passing cations;
Is provided,
The inner peripheral surface of the vent-side container is provided with a vent-side pressing portion that protrudes toward the inside of the vent-side container,
On the inner peripheral surface of the liquid reservoir-side container, a liquid reservoir-side pressing portion that protrudes toward the inside of the liquid reservoir-side container is provided,
A vent side opening, which is a container opening of the vent side container, is directed to the working electrode, a liquid reservoir side opening, which is a container opening of the liquid reservoir side container, is directed to the counter electrode, and the vent side pressing portion and the liquid reservoir In the state where at least a part of the edge portion of the alcohol detection sheet is sandwiched and pressed by the side pressing portion, the alcohol detection sheet is in an airtight container constituted by the vent side container and the liquid reservoir side container. Placed in
The alcohol detection sheet contains a non-volatile acid solution,
The inside of the hermetic container includes a detection space between the bottom plate of the vent-side container and the alcohol detection sheet, and a liquid reservoir between the bottom plate of the liquid reservoir-side container and the alcohol detection sheet. Divided into space and
The sealed container is provided with an inlet and an outlet that connect the outside of the sealed container and the detection space, respectively.
When the measurement target gas containing alcohol is introduced into the detection space from the introduction port and discharged from the discharge port, the alcohol contained in the measurement target gas reacts with the working electrode, and the working electrode An alcohol sensor that generates a current according to the alcohol concentration of the measurement target gas between the counter electrode and the counter electrode. The bottom plate of the vent side container is provided with a container side protrusion protruding toward the vent side opening,
The bottom plate of the reservoir side container is provided with a reservoir side protrusion protruding toward the reservoir side opening,
The alcohol sensor according to claim 1, wherein a central portion including a center of the alcohol detection sheet is pressed by being sandwiched between the container side protrusion and the liquid reservoir side protrusion. The alcohol sensor according to claim 1, wherein the non-volatile acid solution is present between an outer peripheral surface of the alcohol detection sheet and an inner peripheral surface of the sealed container.   The alcohol sensor according to any one of claims 1 to 3, wherein the cation permeable membrane is a perfluorosulfonic acid-polytetrafluoroethylene membrane.   The alcohol sensor according to any one of claims 1 to 4, wherein the first base film and the second base film are formed by sintering a resin powder into a film shape.   The alcohol sensor according to claim 1, wherein the nonvolatile acid solution contains a surfactant. The working electrode is formed by pressing platinum black on the surface of the first base film,
The alcohol sensor according to any one of claims 1 to 6, wherein the counter electrode is formed by pressing platinum black on a surface of the second base film. A film-like alcohol detection sheet provided with a film-like action part, a film-like pair part, and a cation permeable membrane,
The action part is pressed against the surface of the first base film and the first base film formed by sintering the resin powder into a film and having the back surface in contact with one side of the cation permeable membrane. And a working electrode containing platinum black fixed,
The counter part is formed by sintering a resin powder into a film, and a second base film in which a back surface is in contact with a surface opposite to the one surface of the cation permeable membrane, and the second Having a counter electrode containing platinum black pressed and fixed to the surface of the base film,
The cation permeable membrane is a perfluorosulfonic acid-polytetrafluoroethylene membrane,
When the non-volatile acid solution is contained in the first and second base films, hydrogen ions generated by a chemical reaction of alcohol in contact with the working electrode pass through the cation permeable membrane to the counter electrode. Reaching alcohol detection sheet. The alcohol detection sheet according to claim 8, comprising a ventilation side container, a liquid storage side container, and the nonvolatile acid solution.
The inner peripheral surface of the vent-side container is provided with a vent-side pressing portion that protrudes toward the inside of the vent-side container,
On the inner peripheral surface of the liquid reservoir-side container, a liquid reservoir-side pressing portion that protrudes toward the inside of the liquid reservoir-side container is provided,
A vent side opening, which is a container opening of the vent side container, is directed to the working electrode, a liquid reservoir side opening, which is a container opening of the liquid reservoir side container, is directed to the counter electrode, and the vent side pressing portion and the liquid reservoir In the state where at least a part of the edge portion of the alcohol detection sheet is sandwiched and pressed by the side pressing portion, the alcohol detection sheet is in an airtight container constituted by the vent side container and the liquid reservoir side container. Placed in
The inside of the hermetic container includes a detection space between the bottom plate of the vent-side container and the alcohol detection sheet, and a liquid reservoir between the bottom plate of the liquid reservoir-side container and the alcohol detection sheet. Divided into space and
The sealed container is provided with an inlet and an outlet that connect the outside of the sealed container and the detection space, respectively.
When the measurement target gas containing alcohol is introduced into the detection space from the introduction port and discharged from the discharge port, the alcohol contained in the measurement target gas reacts with the working electrode, and the working electrode An alcohol sensor that generates a current according to the alcohol concentration of the measurement target gas between the counter electrode and the counter electrode. The bottom plate of the vent side container is provided with a container side protrusion protruding toward the vent side opening,
The bottom plate of the reservoir side container is provided with a reservoir side protrusion protruding toward the reservoir side opening,
The alcohol sensor according to claim 9, wherein a central portion including a center of the alcohol detection sheet is pressed while being sandwiched between the vent-side protrusion and the liquid reservoir-side protrusion. 11. The alcohol sensor according to claim 9, wherein the nonvolatile acid solution is present between an outer peripheral surface of the alcohol detection sheet and an inner peripheral surface of the sealed container.

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