JP2002071621A - Constant potential electrolytic gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constant potential electrolytic gas sensor with a simple structure capable of preventing a leak of an electrolyte caused by large pressure variations inside and outside an electrolysis vessel. SOLUTION: In this constant potential electrolytic gas sensor, a working electrode 103 serving as a gas electrode for gas detection and chemically reacting a gas to be detected, a counter electrode 104 standing opposite to the working electrode 103, and a reference electrode 105 for controlling the potential of the working electrode 103 are provided so as to face on an electrolyte storage part in the electrolysis vessel 102 stored with the electrolyte 101, a gas introduction part 111 is provided for introducing the gas to be detected to the working electrode 103, and an output circuit for providing a gas detection output is electrically connected to the respective electrodes. A gas storage part 106 is provided in the electrolysis vessel 102 while a vent part 112 is provided for ventilatably connecting the storage part 106 to the introduction part 111.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas electrode for detecting a gas, a working electrode for chemically reacting a gas to be detected, a counter electrode to the working electrode, and a reference electrode for controlling the potential of the working electrode, containing an electrolyte. A constant-potential-electrolytic gas sensor, which is provided facing the electrolyte-containing portion of the electrolyzed electrolytic cell, which is provided with a gas introducing portion for introducing a gas to be detected to the working electrode, and which is electrically connected to an output circuit for obtaining a gas detection output at each of the electrodes. About.

[0002]

2. Description of the Related Art A conventional potentiostatic gas sensor has a structure in which electrodes are provided facing an electrolytic solution accommodating portion of an electrolytic cell in which an electrolytic solution is densely accommodated. For example, the electrodes detect gas. An electrode containing a working electrode for chemically reacting a gas to be detected, a counter electrode to the working electrode, and a reference electrode for controlling the potential of the working electrode is provided as a gas electrode. A tank and a potentiostat circuit for setting the potential of each of the electrodes are connected. As a material for the three electrodes, a gas-permeable porous Teflon (registered trademark) membrane coated with a noble metal catalyst such as platinum, gold, or palladium is used. As an electrolytic solution, an acidic aqueous solution such as sulfuric acid or phosphoric acid is used. Was used. Such a galvanostatic gas sensor applies a galvanostatic analysis method performed in the field of electrochemistry to a gas sensor, and uses a toxic gas such as carbon monoxide present in air as a gas to be detected. Can be detected.

In addition, the constant potential electrolytic gas sensor controls the potential of the working electrode so as to keep it constant with respect to a change in the surrounding environment, so that a change in the surrounding environment can be caused between the working electrode and the counter electrode. Generates a current corresponding to Since the fact that the potential of the working electrode does not change and the oxidation-reduction potential varies depending on the type of gas is used, gas can be selectively detected depending on the potential set in the potentiostat circuit. Further, by changing the catalyst used for the gas electrode, high selectivity can be provided for the target gas.

[0004]

The above-described conventional constant potential electrolytic gas sensor will be described with reference to the drawings.
As shown in (1), an electrolytic solution 101 and a gas container 106 exist inside an electrolytic cell 102. Further, in order to adjust a pressure change inside the electrolytic cell 102 due to an increase or a decrease in the volume of the electrolytic solution 101 in the electrolytic cell due to a change in the humidity of the atmosphere or the like, the vent 301 provided in a place different from the electrode diaphragm 107 is used. A pressure difference is prevented from occurring inside and outside the tank 102. However, the internal pressure is applied to the electrolytic cell 102 with the fluctuation of the volume of the electrolytic solution 101,
Are closely accommodated, the volume fluctuation is absorbed by the volume fluctuation of the electrolytic cell 102 itself. As a result, stress is applied to the peripheral wall of the electrolytic cell 102. In addition, usually, the gas to be detected is supplied to the working electrode 103 in the electrolytic cell 102.
Electrode diaphragm 107 having gas permeability for leading to the electrode diaphragm is used.
For example, a portion having a low strength, such as 07, constituting the peripheral wall of the electrolytic cell 102 was easily damaged.

[0005] Therefore, the gas container 106 is provided in the electrolyte container.
There has been proposed a constant-potential electrolytic gas sensor having a configuration provided with. As described above, by providing the gas storage unit 106, the gas stored in the gas storage unit 106 is compressible, so that the volume fluctuation of the electrolyte 101 is reduced.
06 is absorbed by the compression of the gas and the stress applied to the peripheral wall of the electrolytic cell 102 can be reduced. But,
If the state where the internal pressure is applied to some extent due to the volume fluctuation of the electrolytic solution 101 continues, a load is accumulated on the electrode diaphragm 107 and the like.

Therefore, it has been considered to employ a vent hole 301 in order to further allow the gas storage portion 106 and the atmosphere outside the electrolytic cell 102 to ventilate. With such a configuration, even if the internal pressure continues to be applied in the electrolytic cell 102, the gas container 10
The internal pressure of 6 changes due to the ventilation through the ventilation hole 301 so as to match the atmospheric pressure. That is, pressure balance is maintained so that a load is not easily accumulated on the electrode diaphragm 107 and the like.

However, when a sudden pressure change such as an extreme drop in the pressure of the suction gas in the gas introduction unit 111 occurs, the pressure change does not occur because the electrolyte 101 is incompressible. Because it directly affects 101
There is a problem that the electrolytic solution 101 leaks to the outside of the electrolytic cell 102 through a low-strength portion such as the electrode diaphragm 107 and becomes unusable as a constant potential electrolytic gas sensor. In addition, when the above-mentioned rapid pressure fluctuation occurs, dust in the atmosphere is clogged in the gas introduction unit 111 and becomes blocked, or after performing gas detection in a gas pipe having a pressure higher than the atmospheric pressure. The case where the constant potential electrolytic gas sensor is returned to the atmosphere may be considered.

In some cases, the vent 301 is not provided by using the electrode diaphragm 107 having an excellent withstand voltage characteristic. There is a problem that the electrolytic solution 101 may leak.
When the outside atmospheric pressure becomes high, there is a problem that air bubbles may enter into the electrolytic bath 102 even when there is no leakage of the electrolytic solution 101, and in such a case, the gas to be detected does not exist. It is known that a sensor output (hereinafter referred to as a zero point) in the normal atmosphere becomes unstable. When the air holes 301 are provided, the porous Teflon film 30 is formed so that the electrolyte 101 does not leak from the air holes 301.
2, etc., the vent 301 must be covered, and there is a problem that the manufacturing process and structure of the galvanostatic gas sensor become complicated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a constant potential electrolytic gas sensor capable of preventing electrolyte leakage caused by a large pressure fluctuation inside and outside an electrolytic cell with a simple structure.

[0010]

Means for Solving the Problems [Structure 1] A characteristic structure of the present invention for achieving this object will be described with reference to the drawings. A working electrode 103 for chemically reacting the gas to be detected,
A counter electrode 104 for the working electrode 103 and a reference electrode 105 for controlling the potential of the working electrode 103
The working electrode 103 is provided with a gas introduction unit 111 for guiding a gas to be detected, and an output circuit for obtaining a gas detection output is electrically connected to each of the electrodes. A constant-potential electrolytic gas sensor in which a gas container 106 is provided in the electrolytic cell 102, and the gas container 106 and the gas introduction unit 11 are provided.
1 is provided in such a manner that a ventilation section 112 is provided to allow the ventilation section 1 to freely ventilate (see FIG. 1).

[Effect 1] That is, a working electrode for chemically reacting a gas to be detected, a counter electrode to the working electrode, and a reference electrode for controlling the potential of the working electrode are accommodated in the electrolytic solution as gas electrodes for detecting gas. A conventional constant-potential electrolytic gas sensor as described above, which is provided facing the inside of the electrolytic cell, is provided with a gas introduction unit for guiding the gas to be detected to the working electrode, and electrically connects an output circuit for obtaining a gas detection output to each of the electrodes. The basic structure can be adopted. Here, if at least one reaction catalyst selected from platinum and gold palladium is provided as the working electrode, a hydride gas,
Since it has an oxidizing activity with respect to a gas to be detected such as carbon monoxide, hydrogen, alcohol, and a nitrogen compound, it becomes possible to oxidize the gas to be detected at the working electrode and detect electrons generated by the oxidation. . At this time, if the reference electrode is formed of a material such as silver, graphite, or gold, the reference electrode is configured to be hardly affected by the gas to be detected.

Further, a gas container is provided in the electrolytic cell,
By providing a ventilation portion that freely connects the gas storage portion and the gas introduction portion, gas exchange is freely performed between the gas storage portion and the gas introduction portion, and the internal pressure of the electrolytic cell, The air pressure with the gas inlet fluctuates so as to be kept substantially equal over time. For this reason, even if the pressure of the suction gas in the gas introduction part drops extremely, the internal pressure of the electrolytic cell fluctuates quickly according to the pressure of the gas introduction part. Therefore, it becomes difficult to cause damage to the electrode diaphragm and the like,
The electrolyte did not leak to the outside of the electrolytic cell, and it was possible to always maintain a stable state. Therefore, it was possible to provide a constant-potential-electrolysis-type gas sensor in which the constant-potential-electrolysis-type gas sensor is less likely to be unusable due to a pressure difference between the inside and outside of the electrolytic cell.

Further, it is known that the volume of the electrolytic solution accommodated in the electrolytic solution accommodating portion fluctuates due to moisture absorption and release. It is conceivable that an internal pressure is applied to the electrolytic cell due to a volume change. However, even if the electrolytic solution increases or decreases, the volume of the gas storage unit increases or decreases and the air pressure of the gas storage unit is kept equal to the air pressure of the gas introduction unit by ventilation in the ventilation unit. It is possible to prevent the internal pressure from being applied to the inside of the electrolytic cell based on the volume fluctuation caused by the absorption and release of the liquid.

Further, since the ventilation section is provided as described above, a mechanism such as a pressure valve becomes unnecessary, and the manufacturing process and structure of the constant potential electrolytic gas sensor can be simplified. In addition, since the structure is simplified, maintenance can be facilitated and the manufacturing cost can be reduced, so that a constant potential electrolytic gas sensor for a gas detection alarm for ensuring safety of the working environment is required. It can be provided at low cost.

[Structure 2] The characteristic structure of the present invention for achieving this object will be described with reference to the drawings.
02 and the gas introduction part 111 are provided with a gas-permeable electrode diaphragm 107, and the working electrode 103 is provided on the electrode diaphragm 107 so as to be in contact with the electrolyte 101,
In addition, the electrode diaphragm 107 is provided so as to be freely contactable with the gas storage part 106 to form the ventilation part 112 (see FIG. 1).

[Effect 2] That is, by providing a gas-permeable electrode diaphragm that separates the electrolytic cell from the gas inlet, the electrode diaphragm can freely contact the electrolytic solution and the gas storage part. It can be separated from the gas inlet. Further, the electrode diaphragm is made of a material having gas permeability such as a porous Teflon film, and further, by providing the working electrode which can be in contact with the electrolytic solution on the electrode diaphragm, gas permeability is improved. The electrode diaphragm can be integrated with the electrode, and a function as a vent can be added to the electrode diaphragm. Thus, there is no need to provide a ventilation hole in a place different from the electrode diaphragm, and therefore, only an opening for mounting the electrode diaphragm may be prepared as an electrolytic cell. For this reason, it is possible to provide a potentiostatic electrolytic gas sensor with a simplified manufacturing process and structure. In addition, since the structure is simplified, maintenance can be facilitated and the manufacturing cost can be reduced, so that a constant potential electrolytic gas sensor for a gas detection alarm for ensuring safety of the working environment is required. It can be provided at low cost.

Here, the electrode diaphragm is provided so as to be freely contactable with the electrolytic solution, and the electrode diaphragm is also provided so as to be freely contactable with the gas accommodating portion. The part that is in contact with is the ventilation part. That is, gas exchange is performed between the gas storage unit and the gas introduction unit by the ventilation unit, and therefore, even if the pressure of the suction gas in the gas introduction unit is extremely reduced, the pressure in the electrolytic cell is Since the pressure fluctuates rapidly in accordance with the pressure of the gas introduction unit through the ventilation unit, a characteristic occurs in which the pressure inside the electrolytic cell and the pressure of the gas introduction unit are kept equal. As a result, the air pressure inside the electrolytic cell and the air pressure in the gas inlet become almost equal with time, so that the electrolytic solution does not leak to the outside of the electrolytic cell through the electrode diaphragm, and a constant potential that always maintains a stable state. It becomes an electrolytic gas sensor, and the constant potential electrolytic gas sensor does not become unusable due to a pressure difference between the inside and outside of the electrolytic cell. Also,
As described above, since the air pressure inside the electrolytic cell and the air pressure in the gas introduction section are kept substantially equal with time, a constant-potential electrolytic method that always keeps a stable state because bubbles do not enter the inside of the electrolytic cell. It becomes a gas sensor and can provide a potentiostatic gas sensor having a stable zero point.

Further, as described above, since the ventilation portion is provided, a mechanism such as a pressure valve is not required, and the manufacturing process and structure of the constant potential electrolytic gas sensor can be simplified. Here, a porous Teflon membrane having gas permeability as a material of the electrode material generally has not only gas permeability in a vertical direction to the membrane but also gas permeability in a horizontal direction. I have. For this reason, although the ventilation part is only a part where the electrode diaphragm is in contact with the gas storage part, the porous Teflon film has gas permeability in the horizontal direction with respect to the film. In addition, gas exchange can be efficiently performed on the entire surface of the electrode diaphragm facing the gas inlet.

[Structure 3] The characteristic structure of the present invention for achieving this object will be described with reference to the drawings. As described in claim 3, in the invention described in claim 2, in the invention described in claim 2, the electrode diaphragm 107 is formed. The working electrode 103 and the counter electrode 10
4. The reference electrode 105 is disposed so as to be freely contactable with the electrolyte 101 (see FIG. 1).

[Effect 3] That is, by arranging the working electrode, the counter electrode, and the reference electrode on one electrode diaphragm having a function as a vent, only one electrode diaphragm is provided. In addition, since there is no need to provide a ventilation hole, only one opening for mounting the electrode diaphragm in which the electrodes are arranged may be prepared as the electrolytic cell. This greatly reduces the chance of leakage of the electrolytic solution in the electrolytic cell as compared with an electrolytic cell having a plurality of openings due to the provision of a plurality of electrode diaphragms and vent holes.

Further, since each of the electrodes is arranged on one electrode diaphragm, it is easy to assemble the electrodes and incorporate the electrode diaphragm into the electrolytic cell, and the electrodes are arranged on a plurality of electrode diaphragms. It is possible to provide a potentiostatic electrolytic gas sensor in which the manufacturing process and the structure are simplified as compared with the configuration in which the gas sensors are arranged. Further, the electrode diaphragm is provided so as to be freely contactable with the gas storage portion, and a portion where the electrode diaphragm is in contact with the gas storage portion is used as a ventilation portion. for that reason,
Even if gas exchange is performed between the gas storage unit and the gas introduction unit, and even if the pressure of the suction gas in the gas introduction unit is extremely reduced, the internal pressure of the electrolytic cell is increased through the ventilation unit. Due to the equilibrium between the internal pressure and the pressure of the gas inlet, the pressure fluctuates rapidly according to the pressure of the gas inlet. As a result, the pressure inside the electrolytic cell and the pressure at the gas inlet become substantially equal with time, and damage to the electrode diaphragm due to a pressure difference can be prevented, so that the electrolyte leaks out of the electrolytic cell through the electrode diaphragm. It became difficult to do. Therefore, a stable state can always be maintained, and the constant potential electrolytic gas sensor is less likely to become unusable. Further, as described above, since the pressure inside the electrolytic cell and the pressure in the gas introduction part are quickly and almost kept equal, even if there is a sudden pressure change in the gas introduction part, bubbles are generated in the electrolytic cell. It is possible to provide a potentiostatic gas sensor having a stable zero point which is hard to enter.

In addition, since only one opening for mounting the electrode diaphragm on which the above-mentioned respective electrodes are provided is required as the electrolytic cell, the manufacturing process and structure are simplified, and maintenance is easy. In addition, the manufacturing cost can be reduced, so that a constant-potential electrolytic gas sensor for a gas detection alarm for ensuring the safety of the working environment can be provided at low cost.

[Structure 4] The characteristic structure of the present invention for achieving this object will be described with reference to the drawings. The thickness of the electrolytic cell 102 between the electrode diaphragm 107 and the facing surface in the accommodating portion 106 is formed to be larger than the thickness of the electrolytic cell 102 in the electrolytic solution accommodating portion (see FIG. 3).

[Effect 4] The phenomenon that the amount of the electrolytic solution fluctuates due to moisture absorption and desorption appears more clearly as the total amount of the electrolytic solution in the electrolytic cell is smaller. In other words, when the amount of the electrolyte is sufficiently large, it is difficult to be observed as a phenomenon because the ratio of the increase or decrease of the electrolyte due to moisture absorption and desorption is small relative to the total amount of the electrolyte. Is easily recognized as a change in the liquid level position. Also,
When the liquid level position of the electrolytic solution fluctuates, when the liquid level rises, such as when the ventilation section is formed in the electrode diaphragm, the ventilation section is narrowed or the liquid level is lowered. In such a case, the electrodes formed on the electrode diaphragm are exposed to the gas containing portion, and thus the inconvenience that the function provided does not sufficiently function or the catalyst provided on the electrodes is deteriorated is likely to occur.

In order to alleviate such a phenomenon, it is desirable to secure a sufficient amount of the electrolytic solution in the electrolytic cell and the volume of the gas storage portion. It is difficult to secure the strength of the entire electrolytic cell,
The structure becomes bulky, the degree of freedom in the configuration of the entire apparatus is reduced, and inconveniences such as difficult handling are likely to occur.

Therefore, according to the fourth aspect, the thickness of the electrolytic cell between the electrode diaphragm and the opposing surface in the gas storage portion is set to be larger than the thickness of the electrolytic cell in the electrolytic solution storage portion. When formed, the volume of the gas storage section can be ensured to be large in the thickness direction without significantly changing the volume of the electrolyte storage section. Then, a change in the volume due to moisture absorption and release of the electrolytic solution is observed as a small change in the liquid level because the gas container is thick. Then, it is possible to suppress inconvenience due to a large fluctuation in the liquid level, such as a case where the ventilation portion is narrowed or an electrode is exposed to the gas storage portion.

The drawings are used merely for reference, and the present invention is not limited to the drawings.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto. As shown in FIGS. 1 and 2, the potentiostatic electrolytic gas sensor of the present invention is provided with a casing that forms an electrolytic cell 102 that contains an electrolytic solution 101, and can be freely contacted with the electrolytic solution 101 contained in the electrolytic cell 102. A working electrode 103 for chemically reacting a gas to be detected, a counter electrode 104 for the working electrode, and a reference electrode 105 for controlling the potential of the working electrode are provided. The working electrode 103 and the counter electrode 104 are formed by coating and sintering a noble metal catalyst such as platinum, gold, or palladium on the surface of a porous gas-permeable electrode diaphragm 107, and the reference electrode 105 It is made of silver wire. Here, the reference electrode 105 can be made of any material that is not affected by the gas to be detected, such as graphite or gold, in addition to the silver wire.
Further, the working electrode 103 is disposed on the electrode diaphragm 107, and communicates with the gas introduction portion 111 to form the working electrode 10
A reaction section for reacting the gas to be detected on 3 is formed.
It is also possible to dispose each of the electrodes on one of the electrode diaphragms 107.

Further, a working electrode lead terminal 103a and a counter electrode lead terminal 104 are provided so as to be freely contactable with the respective electrodes.
a, a reference electrode lead terminal 105a is provided on each of the casings, and a reaction part for introducing and reacting a gas to be detected through a pressing member 109 made of a silicone rubber sealing material is formed. A cover member 110 for fixing the pressing member 109 is provided, and the cover member 110 is fitted and fixed to the casing.

Further, a gas container 106 in which an atmospheric gas is present is provided above the electrolytic cell 102, and a portion where the electrode diaphragm 107 is in contact with the gas container 106 serves as a vent 112. The ventilation section 112 is provided in the electrolytic cell 1.
A vent hole may be provided in the gas supply port 02 so as to communicate with the gas inlet 111 (not shown).

Such a potentiostatic electrolytic gas sensor is provided with a gas introducing section 111 for introducing a gas to be detected into the reaction section, and a current measuring section capable of detecting a current based on electrons generated on the working electrode 103. 201 and the working electrode 1
03 is connected to a gas detection circuit provided with a potential control unit 202 capable of controlling the potential and used as a gas detection device.

As shown in FIG. 3, the thickness of the electrolytic cell 102 in the gas container 106 between the electrode diaphragm 107 and the facing surface is larger than the thickness of the electrolytic cell 102 in the electrolytic solution container. It is also possible to form it.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. Using a conventional potentiostatic gas sensor and the potentiostatic gas sensor of the present invention, the pressure at the gas inlet is set lower than the atmospheric pressure, and the results obtained by measuring the zero point with both sensors are shown. It is shown in FIG. Such a situation is considered to be a case where dust or the like in the atmosphere is clogged in the gas introduction unit and the gas introduction unit is closed. The configuration of the potentiostatic electrolytic gas sensor of the present invention is such that platinum black is used for the working electrode and the catalyst of the counter electrode,
A silver wire is used as a reference electrode, a porous Teflon film is used as an electrode diaphragm, and 1.5 ml of a sulfuric acid (H ₂ SO ₄ ) solution is used as an electrolyte. At this time, the volume of the electrolytic cell was 3.
It is 0 ml. Such a constant potential electrolytic gas sensor is used as a sensor for detecting carbon monoxide (CO). Further, a conventional constant potential electrolytic gas sensor having the same configuration as the above-described conventional constant potential electrolytic gas sensor of the present invention is used.

Here, the horizontal axis in FIG. 5 is time (seconds), and the vertical axis is the zero point output (m
V). As a result, the conventional constant-potential electrolytic gas sensor has a pressure lower than the atmospheric pressure of -3 kPa and -40 kPa.
The zero point fluctuated for both kPa. In particular, at −40 kPa, the zero point fluctuated greatly, and an output equivalent to atmospheric pressure could not be maintained after the zero point measurement, and the electrolyte in the electrolytic cell leaked. On the other hand, in the potentiostatic gas sensor of the present invention, the zero point fluctuation is extremely small at both -3 kPa and -40 kPa which are pressure conditions lower than the atmospheric pressure, and the pressure at which electrolyte leakage occurs in the conventional potentiostatic electrolytic gas sensor. No abnormalities were observed. That is, the potentiostatic electrolytic gas sensor of the present invention is a condition in which a pressure difference occurs inside and outside the electrolytic cell.
It has been found that even when actually used under the condition where the pressure in the gas introduction part is lower than the atmospheric pressure, the electrolyte has a stable zero point because the electrolyte does not leak or bubbles are not generated.

On the other hand, the pressure at the gas inlet is set higher than the atmospheric pressure using the conventional potentiostatic gas sensor and the potentiostatic gas sensor of the present invention, and the zero point is measured by both sensors. The results obtained are shown in FIG. Such a situation may be the case where the gas is detected in a gas pipe having a pressure higher than the atmospheric pressure, and then the constant potential electrolytic gas sensor is returned to the atmosphere. The configuration of the conventional constant-potential electrolytic gas sensor and the constant-potential electrolytic gas sensor of the present invention are the same as those described in the above embodiments.

Here, the horizontal axis in FIG. 6 is time (seconds), and the vertical axis is zero point output (mV) expressed as a relative value to the atmospheric pressure. As a result, in the conventional potentiostatic gas sensor, the zero point becomes very unstable at both 1 kPa and 3 kPa which are conditions higher than the atmospheric pressure, and it is difficult to return to the atmospheric pressure level especially after the zero point measurement at 3 kPa. there were. On the other hand, in the potentiostatic electrolytic gas sensor of the present invention, the zero point fluctuation was extremely small at 1 kPa and 3 kPa which are higher than the atmospheric pressure, and the return to the atmospheric pressure level after the zero point measurement was normal. That is, even if the constant potential electrolytic gas sensor of the present invention is actually used under the condition that a pressure difference is generated inside and outside the electrolytic cell, that is, the pressure in the gas introduction part is higher than the atmospheric pressure, the leakage of the electrolytic solution can be prevented. Since no bubbles or bubbles were generated, it was found to have a stable zero point.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a potentiostatic gas sensor of the present invention.

FIG. 2 is a perspective view of the potentiostatic gas sensor of FIG. 1;

FIG. 3 is a schematic view of another embodiment of the potentiostatic gas sensor of the present invention.

FIG. 4 is a schematic diagram of a conventional potentiostatic gas sensor.

FIG. 5 is a graph showing the variation of the zero point output when the pressure of the gas inlet is reduced. (A) Conventional potentiostatic gas sensor (b) Potentiometric electrolytic gas sensor of the present invention

FIG. 6 is a graph showing the variation of the zero point output when the pressure of the gas introduction unit is increased. (A) Conventional potentiostatic gas sensor (b) Potentiometric electrolytic gas sensor of the present invention

[Explanation of symbols]

101 Electrolyte 102 Electrolyzer 103 Working electrode 103a Working electrode lead terminal 104 Counter electrode 104a
Counter electrode lead terminal 105 Reference electrode 105a Reference electrode lead terminal 106 Gas container 107 Electrode diaphragm 109 Holding member 110 Cover member 111 Gas introduction unit 112 Ventilation unit 201 Current measurement unit 202
Potential control section 301 Vent 302 Porous Teflon film

Claims (4)

[Claims] An electrolytic solution in an electrolytic cell containing an electrolytic solution, comprising: a working electrode for chemically reacting a gas to be detected as a gas electrode for detecting a gas; a counter electrode to the working electrode; and a reference electrode for controlling the potential of the working electrode. A constant-potential-electrolysis-type gas sensor which is provided facing a housing portion, is provided with a gas introduction portion for guiding a gas to be detected to the working electrode, and electrically connects an output circuit for obtaining a gas detection output to each of the electrodes; A galvanostatic gas sensor having a gas storage portion provided in a tank and a ventilation portion for connecting the gas storage portion and the gas introduction portion in a freely permeable manner. 2. A gas permeable electrode diaphragm for partitioning the electrolytic cell and the gas inlet, a working electrode which is freely contactable with the electrolytic solution is provided on the electrode diaphragm, and the electrode diaphragm is formed of the gas. 2. The potentiostatic gas sensor according to claim 1, wherein the ventilation portion is formed so as to be freely contactable with the housing portion. 3. The potentiostatic electrolytic gas sensor according to claim 2, wherein the working electrode, the counter electrode, and the reference electrode are arranged on the electrode diaphragm so as to be freely contactable with the electrolytic solution. 4. The electrolytic cell in the gas storage section between the electrode diaphragm and the opposing surface is formed to be thicker than the electrolytic cell in the electrolytic solution storage section. 4. The potentiostatic electrolytic gas sensor according to 3.