JP4620215B2 - Diaphragm sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diaphragm type sensor having a structure in which a detection electrode, a counter electrode, an electrolytic solution (internal liquid) and the like are held in a sensor body and a gas-liquid separation membrane. More specifically, the present invention relates to a diaphragm type sensor that is suitable for detection of low-concentration gas such as chlorine leakage gas and can be manufactured minutely.
[0002]
[Prior art]
As sensors for detecting toxic gases such as chlorine gas, centimeter-sized coulometric and constant potential electrolytic sensors have been put into practical use. The sensor is widely used for leaked gas detection alarms and the like, and is a sensor having the capability of quickly responding to a low-concentration gas near an allowable concentration (ACGIH or recommended value of the Japan Society for Occupational Health).
[0003]
These coulometric and constant-potential electrolytic chlorine gas sensors have a structure in which an internal liquid (electrolyte) is held together with a working electrode (detection electrode), a counter electrode, etc. inside a gas-liquid separation membrane (diaphragm) and the sensor body It has become. Both methods have many similarities, such as measuring the current as the sensor output while applying an appropriate voltage between the working electrode, and recently, other similar measurement methods can be used regardless of the measurement principle. In addition, cases called amperometric sensors, amperometric sensors, electrochemical sensors, and EC (Electrochemical) sensors are increasing.
[0004]
FIG. 9 shows an example of an EC sensor according to the above prior art. The EC sensor shown in FIG. 9 includes a cylindrical sensor main body 51 and a diaphragm holder 53 that holds a porous diaphragm 52 in the center. The diaphragm holder 53 is attached to the tip of the sensor body 51 via the O-ring 55 by screwing the nut 54 with the sensor body 51. In addition, an electrode support 56 is suspended from the upper part of the sensor (not shown) in the central space of the electrode body 51, a detection electrode 57 is provided at the tip of the electrode support 56, and a counter electrode 58 is provided in the intermediate recess. It is supported. The space formed between these members is filled with the electrolytic solution 59. The size of the entire EC sensor is, for example, 26 mmΦ × 58 mm.
[0005]
On the other hand, research and development of micro gas sensors have been performed by many researchers so far, and many reports have been made. However, most of the reports on micro EC sensors are about oxygen sensors or biosensors. This is because the need for these microsensors exists in the medical field, and because of the high concentration (% order) of oxygen as the measurement target substance, the gas-liquid with a small pore size and porosity. Because it can be used as a separation membrane, and a film such as a fluorine compound or silicone can be used, a gas-liquid separation structure can be constructed relatively easily, and the internal solution of the oxygen sensor has a composition close to that of a potassium chloride solution. The fact that the surrounding sensor members and the like are hardly eroded is greatly involved, and it is considered that many research reports have been made.
[0006]
FIG. 10 shows an oxygen electrode described in Japanese Patent Publication No. 6-1254 as an example of the minute sensor. In FIG. 10, a silicon substrate 71 has a groove formed by anisotropic etching, and an insulating film 72 is deposited on the entire surface thereof. In the groove of the silicon substrate 71, two gold electrodes 73A and 73B are bonded in pairs. Each of the gold electrodes 73A and 73B extends to the outside of the groove. The groove of the silicon substrate 71 is filled with a gel 74 containing an electrolytic solution. Further, the groove is covered with a gas permeable film 75 formed by applying a liquid material so as to cover the entire upper surface of the silicon substrate 71. The size of this sensor is 4 mm wide × 15 mm long × 350 μm thick.
[0007]
[Problems to be solved by the invention]
Also in the conventional EC sensor shown in FIG. 9, miniaturization is desired from the viewpoint of enabling installation in a narrow place near a place that can be a generation source and promoting cost reduction. In addition, miniaturization is also desired for energy saving and environmental considerations such as reducing the amount of waste including electrolytes.
[0008]
However, it cannot be manufactured by miniaturizing the structure as it is. That is, the O-ring 55, the nut 54, and the like that are used to securely hold the electrolytic solution 59 inside have a limit even when trying to reduce the size. Further, the positional relationship between the detection electrode 57 and the diaphragm 52 is a sensor such as the thickness of the layer of the electrolytic solution 59 in which the gas to be measured that has passed through the diaphragm 52 dissolves, the distance until the gas to be measured reaches the detection electrode 57, and the like. Strict management is necessary because it directly affects matters that affect the sensitivity of the system. However, even if the O-ring 55 and the like can be miniaturized, it is difficult to strictly manage the positional relationship between the detection electrode 57 and the diaphragm 52 by a method of tightening a nut in a minute size.
[0009]
On the other hand, the configuration like the oxygen electrode shown in FIG. 10 is not applied to a micro EC sensor for measuring toxic gas. This is because, in the above configuration, it is difficult to achieve the specification that the gas to be measured is a low-concentration gas of the order of ppb to ppm and that quick response and long-term stability are required for the following reasons.
[0010]
That is, in the case of low concentration measurement, it is necessary to use a gas-liquid separation membrane that can reliably retain the internal liquid while ensuring sufficient gas permeability. However, the film formed by applying the liquid material on the oxygen electrode is a non-porous film. In this case, since the gas permeates through the molecules constituting the continuous film, only a very small part of the gas in contact with the film can permeate. This can be used as long as a gas of around 20% is measured, such as oxygen. However, when a low-concentration gas of the order of ppb to ppm is targeted, a sufficient amount of permeation cannot be ensured.
[0011]
Further, in the oxygen electrode of FIG. 10, the electrolytic solution is made non-liquid and has some mechanical strength, thereby enabling application of a liquid material that forms a gas-liquid separation membrane. Therefore, it is difficult to make the positional relationship between the gas-liquid separation membrane and the detection electrode constant, and in the case of low concentration measurement, there is a problem in accuracy.
[0012]
The present invention has been made in view of the above circumstances, and even when it is miniaturized, it can ensure sufficient gas permeability that can accommodate measurement of low-concentration gas, and can also reliably hold internal liquid, It is an object of the present invention to provide a diaphragm type sensor that can obtain good measurement accuracy by performing precise processing such as making the positional relationship between a detection electrode and a gas-liquid separation membrane constant.
[0013]
[Means for Solving the Problems]
As a result of studying the above problems, the inventors of the present invention have, as the invention of claim 1, a sensor main body, a gas-liquid separation membrane, an electrolytic solution filled between the sensor main body and the gas-liquid separation membrane, and an electrolytic solution. In a diaphragm type sensor having a sensing electrode and a counter electrode that are in contact with each other, the gas-liquid separation membrane is constituted by a membrane material obtained by perforating a silicon wafer or a membrane material obtained by anodizing alumina and making the sensor body, One or more membrane joint surfaces provided on the same plane to which the gas-liquid separation membrane is joined, an electrolyte containing groove provided at a position surrounded by the membrane joined surface, and spaced apart from the membrane joined surface from the bottom surface of the electrolyte containing groove And a detection electrode base that protrudes to the vicinity of the same plane as the membrane bonding surface, and a detection electrode is formed on the bottom of the electrolyte storage groove at the front end of the detection electrode base of the sensor body. Each has a counter electrode, and the detection electrode is connected to the membrane interface. It is positioned closer to the bottom surface of the electrolyte storage groove than on one plane, and the positional relationship between the gas-liquid separation membrane and the detection electrode is held in a stable relationship by the positional relationship between the membrane interface and the detection electrode base. A diaphragm type sensor is provided.
[0014]
The gas-liquid separation membrane in the present invention is generally also referred to as a diaphragm. The electrolytic solution is also referred to as an internal solution. Further, the detection electrode and the counter electrode are also referred to as a working electrode and a counter electrode in the current measurement type sensor, respectively. In addition, in consideration of the direction of electron exchange, either of the electrodes may be referred to as an anode and either as a cathode. Further, in the voltage measurement type sensor, the detection electrode and the counter electrode are also referred to as a sensitive electrode (membrane) and a reference electrode, respectively. The diaphragm type sensor according to the present invention corresponds to the measurement target gas that passes through the gas-liquid separation membrane and enters the electrolytic solution between the detection electrode and the counter electrode regardless of the presence of these various measurement principles and alternative names. The present invention is intended for all diaphragm type sensors that detect electrical signals obtained by any method.
[0015]
In the present invention, as the electrolytic solution, in addition to a liquid form, a non-liquid form such as a sol form added with a viscous substance, a semi-solid form or a solid form soaked in a gel-forming substance or a resin, etc. can be adopted. . The membrane bonding surface may be formed as a single surface surrounding the electrolyte accommodating groove, such as a donut shape or a square frame, and two or more membrane bonding surfaces are the same so as to surround the electrolyte accommodating groove You may arrange | position on a plane.
[0016]
In the present invention, since the sensor body has a simple structure, a minute size and shape can be processed with high accuracy. Since the gas-liquid separation membrane is bonded to the membrane bonding surface, a gas-liquid separation membrane that can ensure sufficient gas permeability can be selected and mounted. The gas-liquid separation membrane and the detection electrode can maintain a stable positional relationship by the membrane bonding surface and the detection electrode base. Therefore, even if it is a very small size, it is possible to measure with high accuracy. In addition, the internal liquid can be reliably held regardless of whether it is liquid or non-liquid.
[0017]
According to the first aspect of the present invention, the processing is further facilitated by specifying the shape of the sensor body more. That is, as in the invention described in claim 2, the sensor main body, the gas-liquid separation membrane, the electrolytic solution filled between the sensor main body and the gas-liquid separation membrane, the detection electrode and the counter electrode in contact with the electrolytic solution, The gas-liquid separation membrane is made of a membrane material obtained by perforating a silicon wafer or a membrane material made porous by anodic oxidation of alumina, and the sensor body is provided in parallel with the same plane. A pair of membrane bonding surfaces to which the gas-liquid separation membrane is bonded, a bottom surface provided at a position sandwiched between the membrane bonding surfaces, and a rectangular electrolyte solution containing groove, and a projecting end from the bottom surface of the electrolyte containing groove, and the tip is a membrane The front end surface extending to the vicinity of the same plane as the bonding surface has a rectangular detection electrode base parallel to the membrane bonding surface, and the detection electrode is disposed on the front end surface of the detection electrode base of the sensor body. A counter electrode is provided on the bottom of each groove, The electrode is positioned closer to the bottom surface of the electrolyte accommodating groove than on the same plane as the membrane junction surface, and the positional relationship between the gas-liquid separation membrane and the detection electrode is stabilized by the positional relationship between the membrane junction surface and the detection electrode base. It can be set as the diaphragm type sensor characterized by being hold | maintained.
[0018]
According to the present invention, since the electrolytic solution containing groove and the detection electrode base can be provided by linear processing, the manufacturing is easy. The shape of the entire sensor body is not particularly limited, and may be, for example, a cylinder or the like. However, if the sensor body is surrounded by a straight line such as a rectangular parallelepiped, the manufacturing becomes easier.
[0019]
Although there is no particular limitation on the material of the sensor body, as described in claim 3, by using a glass such as quartz, it is possible to quickly perform an accurate process with an inexpensive material. Further, it is difficult to be corroded by the electrolytic solution, and can be applied to diaphragm electrodes having various measurement principles. In addition to this, a resin material or the like can be appropriately used as the material of the sensor body.
[0020]
As described in claim 4, the gas-liquid separation membrane can be a porous membrane whose inner surface facing the electrolyte is hydrophilic and whose outer surface facing the sample gas is water repellent. According to the present invention, since the outer surface is made water-repellent, the electrolyte is difficult to leak to the outside. Therefore, a porous film having a high porosity that can ensure sufficient gas permeation can be employed. In addition, it is less susceptible to external dirt. Furthermore, since the inner surface in contact with the electrolytic solution is made hydrophilic, the compatibility with the electrolytic solution is good. Therefore, even if the distance between the detection electrode and the gas-liquid separation membrane is made as narrow as possible, the detection electrode can contact the electrolyte. Therefore, the entire sensor can be made smaller.
[0021]
According to the present invention, the current flowing when the polarization between the electrodes is released by the measurement target gas that has passed through the gas-liquid separation membrane by applying a voltage between the detection electrode and the counter electrode. A detection method, that is, a coulometric method can be used. In the case of the coulometric method, a neutral electrolyte solution having almost no chemical erosion property can be used. Therefore, not only glass and the like, but various materials can be used, so that it can be applied to miniaturization of sensors using semiconductor processing technology.
[0022]
The coulometric gas sensor can be configured as a chlorine gas sensor, for example, as described in claim 6. In this case, a bromide ion solution is used as the electrolytic solution. In addition, as a material of a detection electrode and a counter electrode, various noble metals, such as platinum, silver, gold | metal | money, praseodymium, palladium, iridium, rhodium, can be selected.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing one embodiment of a diaphragm type sensor according to the present invention. The diaphragm type sensor shown in FIG. 1 includes a sensor main body 1, a detection electrode 2 and a counter electrode 3 provided on the sensor main body 1, and a gas-liquid separation film 4.
[0024]
The diaphragm type sensor in FIG. 1 will be described in more detail with reference to FIGS. 2 is a plan view, FIG. 3 is a plan view excluding the gas-liquid separation membrane 4, and FIGS. 3 to 7 are sectional views taken along lines IV to VII in FIG. 2, respectively.
[0025]
As shown in FIGS. 3 and 4, the sensor body 1 includes membrane bonding surfaces 5 a and 5 b. The membrane bonding surfaces 5a and 5b are rectangular and are provided in parallel to each other on the same plane. In addition, an electrolyte solution containing groove 6 having a rectangular bottom surface is provided at a position between the membrane bonding surfaces 5a and 5b so that the electrolyte solution 7 is accommodated. In addition, a detection electrode base 8 protrudes from the central portion of the electrolytic solution housing groove 6. The tip of the detection electrode base 8 extends to the vicinity of the same plane as the membrane bonding surfaces 5a and 5b, and the tip surface has a rectangular shape parallel to the membrane bonding surfaces 5a and 5b.
[0026]
The detection electrode 2 is provided on the distal end surface of the detection electrode base 8. Moreover, the counter electrode 3 is provided so that the detection electrode base 8 may be pinched | interposed into the remaining bottom face part in which the detection electrode base 8 of the electrolytic solution accommodation groove | channel 6 is not provided. A lead wire 9 is led out from the detection electrode 2 as shown in FIG. Further, a lead wire 10 is led out from the counter electrode 3 as shown in FIG. In addition, illustration of these lead wires 9 and 10 is abbreviate | omitted in FIG.
[0027]
The gas-liquid separation membrane 4 is bonded to the membrane bonding surface 5b (and 5a) as shown in FIG. 7, and covers the sensor body 1 to a position that does not hinder the lead wires 9 and 10 from being drawn as shown in FIG. . The sensor body 1 itself is also provided with cuts in portions not covered with the gas-liquid separation membrane 4 in order to easily lead out the lead wires 9 and 10. The sensor body 1 is appropriately provided with a thin notch in each part for the purpose of electrical insulation between the detection electrode 2 and the counter electrode 3.
[0028]
In this embodiment, the sensor main body 1 is made of quartz glass, and is precisely processed into a desired dimensional shape by a precision dicing saw. In addition, as a processing method of the sensor main body, laser processing or the like may be used, and semiconductor processing technology such as etching may be appropriately employed. The detection electrode and the counter electrode are formed in a film shape on the sensor body by a known method such as vapor deposition, sputtering, or ion vapor deposition (I-BAD). For the lead wires 9 and 10 from both poles, an extremely fine gold wire or the like is used.
[0029]
As the gas-liquid separation membrane 4, a porous membrane made of a fluorine compound such as tetrafluoroethylene is used in the electrode according to the prior art in FIG. 9, but it is suitable for making as a microelectrode because it is easy to loosen. Absent. As a result of investigation, a film material obtained by perforating a silicon wafer by deep RIE (reactive ion etching), a film material obtained by anodizing alumina and making it porous, and the like can be suitably used. For example, a through-hole having a pore size of approximately 30 μm to 100 μm can be formed by deep RIE on a silicon wafer having a thickness of 160 μm. Further, a through-hole having a pore size of about 0.08 μm can be opened in an alumina having a thickness of 10 μm by an anodic oxidation method.
[0030]
In addition, silanization or plasma CVD (chemical vapor deposition) can be suitably used to make the gas-liquid separation film 4 water repellent. The treatment for water repellency may be performed on both sides of the membrane, but the gas-liquid separation membrane 4 and the detection electrode 2 can be brought closer to the limit when only the outer side contacting the sample gas is used. Thus, a finer electrode can be obtained.
[0031]
As a method for bonding the gas-liquid separation membrane 4 to the sensor body 1, a bonding method such as bonding, anodic bonding, hydrofluoric acid bonding, or water glass bonding can be appropriately employed. In order to further stabilize the positional relationship between the gas-liquid separation film 4 and the detection electrode 2, an appropriate spacer is provided on the tip surface of the detection electrode base 8, and gas-liquid separation is performed between the spacer and the membrane bonding surfaces 5a and 5b. The membrane 4 may be supported.
[0032]
The electrolytic solution 7 is injected into the electrolytic solution housing groove 6 through a thin syringe or tube after the gas-liquid separation membrane 4 is joined to the sensor body 1. The electrolytic solution 7 is sufficiently held by the capillary phenomenon to the position in contact with the gas-liquid separation membrane 4 by forming the sensor body small, but the exposed portion of the electrolytic solution 7 is coated with an adhesive or the like. By doing so, evaporation and leakage can be accurately prevented, and handling becomes easier.
[0033]
According to this embodiment, the processing of the sensor body 1 is easy, and the whole can be accurately manufactured with a millimeter size of about 5 mm × 5 mm × 3 mm. In addition, by bonding the gas-liquid separation film to the membrane bonding surfaces 5a and 5b of the sensor body 1, the positional relationship between the gas-liquid separation film 4 and the detection electrode 2 can be satisfactorily stabilized. Furthermore, the gas-liquid separation membrane 4 can ensure sufficient gas permeability that can cope with the measurement of low-concentration gas, and can also reliably hold the internal liquid. That is, according to this embodiment, a microelectrode capable of measuring a low concentration gas such as a toxic gas can be provided.
[0034]
【Example】
As an example of the present invention, a chlorine sensor was created with the structure shown in FIGS. 1 to 7 as an embodiment. In this example, the sensor body 1 was manufactured by processing a quartz glass block of 5 mm × 5 mm × 3 mm with a precision dicing saw. Specifically, the membrane bonding surfaces 5a and 5b are left approximately 1 mm wide on both sides, and the electrolyte accommodating groove 6 is 3 mm wide at the center of the quartz glass block, and further the base of the detection electrode base 8 at the center. The part was provided with a width of 1 mm. The distance between the tip surface of the detection electrode base 8 and the plane on which the membrane bonding surfaces 5a and 5b exist was about 0.1 mm.
[0035]
The detection electrode 2 and the counter electrode 3 are made of platinum, and a concentrated bromide ion solution was used as the electrolyte solution 7. The detection electrode 2 and the counter electrode 3 were provided by ECR sputtering after the membrane bonding surfaces 5a and 5b were previously registered. Specifically, the resist was formed by spin-coating a positive type resist on a quartz glass block after spin-coating an adhesion reinforcing agent. In addition, ECR sputtering was performed using an EIS-200ER apparatus manufactured by Elionix Co., with titanium as a binder. Thereafter, ultrasonic cleaning was performed using ethanol, the resist was removed, and titanium and platinum sputtered on the membrane bonding surface 4 were removed. As a result, an electrode having a titanium layer of about 12 nm and a platinum layer of about 120 nm could be formed. Both ends of the detection electrode 2 were cut with a dicing saw so that the surface area of the detection electrode 2 was 0.1 mm × 3.3 mm. The counter electrode 3 having a surface area of 1 mm × 5 mm was formed at a position sandwiching the detection electrode base 8 on the bottom surface of the electrolytic solution housing groove 6. Gold wires with a diameter of 25 μm were wire-bonded as lead wires 9 and 10 to both electrodes.
[0036]
As the gas-liquid separation membrane 4, a silicon wafer having a thickness of 160 μm with a through hole having a pore size of φ30 μm formed by Deep RIE was used for water repellency by silanization treatment. The silanization treatment was performed by leaving the film after deep RIE processing for 24 hours in a desiccator containing 1,1,1,3,3,3-hexamethyldisilazane as a treating agent. The gas-liquid separation membrane 4 was bonded to the sensor main body 1 by applying a thin silicone adhesive and then bonding them together and leaving them for 24 hours or longer to bond and cure.
[0037]
When a voltage (250 to 300 mV) is applied between both electrodes of the sensor manufactured as described above, the next reaction takes place at the counter electrode 3 and the current is temporarily stopped.
2H ⁺ + 2e ⁻ → H ₂ (1)
When the chlorine gas that has permeated the gas-liquid separation membrane 4 enters the electrolytic solution 7, a halogen exchange reaction occurs and bromine gas is generated at the detection electrode 2.
2Br ⁻ + Cl ₂ → Br ₂ + 2Cl ⁻ (2)
These bromine and hydrogen react to depolarize (depolarize) and a current flows.
Br ₂ + H ₂ → 2Br ⁻ + 2H ⁺ (3)
By detecting this current, the chlorine concentration in the sample gas can be obtained.
[0038]
FIG. 8 shows data obtained by the chlorine sensor of the above example. As shown in FIG. 8, the relationship between the obtained current I and the chlorine concentration C is I = -15.35C-1.033 (nA), the correlation coefficient = 0.999, and good linearity is obtained. It was. Good characteristics equivalent to the conventional sensor shown in Fig. 9 were obtained in terms of repeatability and response speed, and it was confirmed that it has the capability to handle low concentration measurements near the permissible concentration as a toxic gas. .
[0039]
Since the current value is proportional to the chlorine gas concentration to be detected, the current obtained by the sensor of this embodiment is nA level, which is significantly smaller than the μA level obtained by the conventional sensor of FIG. As a result, the current consumption of the amplifier is reduced, so that the power consumption of the entire apparatus can be significantly reduced. That is, the miniaturization of the sensor not only provides convenience of handling due to a small size but also brings about an effect of reducing power consumption, and enables battery driving of the entire apparatus.
[0040]
【The invention's effect】
According to the present invention, sufficient gas permeability that can cope with measurement of low concentration gas even when miniaturized can be secured, the internal liquid can be securely held, and the detection electrode and the gas-liquid separation membrane can be maintained. It is possible to provide a diaphragm type sensor that can obtain good measurement accuracy by performing precise processing such as fixing the positional relationship.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a diaphragm type sensor according to an embodiment of the present invention.
FIG. 2 is a plan view of a diaphragm type sensor according to an embodiment of the present invention.
3 is a plan view obtained by removing the gas-liquid separation membrane 4 from the plan view of FIG. 2. FIG.
4 is a cross-sectional view taken along the line IV-IV of the plan view of FIG.
5 is a VV cross-sectional view of the plan view of FIG. 2. FIG.
6 is a VI-VI cross-sectional view of the plan view of FIG. 2. FIG.
7 is a cross-sectional view taken along the line VII-VII of the plan view of FIG.
FIG. 8 is data obtained by a chlorine sensor according to an example of the present invention.
FIG. 9 is an example of an EC sensor according to the prior art.
FIG. 10 is a micro oxygen electrode according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Detection electrode 3 Counter electrode 4 Gas-liquid separation membrane 5a, 5b Membrane joint surface 6 Electrolyte accommodating groove 7 Electrolyte 8 Detection electrode base 9, 10 Lead wire

Claims (6)

In a diaphragm type sensor comprising a sensor body, a gas-liquid separation membrane, an electrolyte filled between the sensor body and the gas-liquid separation membrane, and a detection electrode and a counter electrode in contact with the electrolyte,
The gas-liquid separation membrane is composed of a membrane material that has been perforated in a silicon wafer or a membrane material that has been made porous by anodizing alumina.
The sensor main body is provided on the same plane and has one or more membrane bonding surfaces to which the gas-liquid separation membrane is bonded; an electrolyte containing groove provided at a position surrounded by the membrane bonding surface; and a membrane from the bottom of the electrolytic solution containing groove A detection electrode base that protrudes away from the bonding surface and extends to the vicinity of the same plane as the membrane bonding surface, and the detection electrode is disposed at the tip of the detection electrode base of the sensor body. A counter electrode is provided on the bottom surface of the groove, and the detection electrode is positioned in the bottom surface direction of the electrolyte solution storage groove rather than on the same plane as the membrane bonding surface, and the positional relationship between the gas-liquid separation membrane and the detection electrode is The diaphragm type sensor is configured to be held in a stable relationship by the positional relationship between the detection electrode base and the detection electrode base. In a diaphragm type sensor comprising a sensor body, a gas-liquid separation membrane, an electrolyte filled between the sensor body and the gas-liquid separation membrane, and a detection electrode and a counter electrode in contact with the electrolyte,
The gas-liquid separation membrane is composed of a membrane material that has been perforated in a silicon wafer or a membrane material that has been made porous by anodizing alumina.
A sensor body is provided in parallel to the same plane and a gas-liquid separation membrane is joined to a pair of membrane joining surfaces, an electrolyte solution containing groove having a rectangular bottom surface provided between the membrane joining surfaces, A leading end surface protruding from the bottom surface of the liquid storage groove and extending to the vicinity of the same plane as the membrane junction surface, and a rectangular detection electrode base parallel to the membrane junction surface. A sensing electrode is provided on the front end surface, and a counter electrode is provided on the bottom surface of the electrolytic solution housing groove, and the sensing electrode is located on the bottom surface side of the electrolytic solution housing groove rather than on the same plane as the membrane bonding surface. A diaphragm type sensor characterized in that the positional relationship between the electrode and the detection electrode is maintained in a stable relationship by the positional relationship between the membrane bonding surface and the detection electrode base.  The diaphragm type sensor according to claim 1 or 2, wherein the sensor body is made of glass.  4. The gas-liquid separation membrane according to any one of claims 1 to 3, wherein the inner surface facing the electrolyte is hydrophilic and the outer surface facing the sample gas is a water-repellent porous membrane. Diaphragm sensor.  The voltage applied between the detection electrode and the counter electrode, and the current flowing when the polarization between the two electrodes is released is detected by the measurement target gas that has permeated through the gas-liquid separation membrane. Item 5. The diaphragm type sensor according to any one of Items 4 to 6.  6. The diaphragm type sensor according to claim 5, wherein the gas to be measured is chlorine gas and a bromide ion solution is used as the electrolyte.

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