JP5112119B2 - Gas detector - Google Patents

Description

  The present invention relates to a gas detection device including a sensor having an electrolytic solution such as a constant potential electrolytic gas sensor.

  At present, for example, when detecting a toxic gas in a semiconductor manufacturing factory, the gas concentration can be detected with high sensitivity and high accuracy with excellent selectivity of the target gas to be detected. A constant potential electrolytic gas sensor using an electrolytic reaction is widely used.

As a certain type of constant potential electrolytic gas sensor, for example, a cell having an opening for accommodating an electrolyte solution for accommodating an electrolyte solution and having two openings that are closed by a porous sheet having gas permeability A working electrode for electrolyzing the gas to be detected, provided on the surface of one porous sheet, and a counter electrode for the working electrode, separated from the counter electrode for the other porous sheet A device provided with a reference electrode for controlling the potential of the working electrode is widely used.
In the constant potential electrolytic gas sensor having such a configuration, in a state where the working electrode, the counter electrode, and the reference electrode are immersed in the electrolytic solution, the gas to be detected is electrolyzed in the working electrode, so that the working electrode and the counter electrode are separated. The detected gas concentration is detected by measuring the electrolytic current value by utilizing the proportional relationship between the magnitude of the electrolytic current value generated due to the electrochemical reaction that occurs and the detected gas concentration. .

However, the sulfuric acid aqueous solution generally used as the electrolytic solution in the above-mentioned constant potential electrolytic gas sensor absorbs the moisture of the outside air such as the gas to be detected due to its water absorption, and the electrolytic solution volume increases and the internal gas escapes. The problem is that the electrolyte may leak to the outside of the cell due to the increase in pressure inside the cell due to the obstruction, resulting in a short circuit between the working electrode, counter electrode and reference electrode. There is.
For such a problem, for example, measures are taken to prevent leakage of the electrolytic solution, such as forming a space that can absorb the increased amount of the electrolytic solution inside the cell (Patent Literature). 1).

JP 2001-099811 A

  The present invention has been made based on the circumstances as described above, and it is possible to prevent malfunctions and equipment damage from occurring by detecting leakage of the electrolyte of the gas sensor. An object of the present invention is to provide a gas detection device capable of maintaining the operating state.

The gas detection device of the present invention is a gas detection device comprising a sensor substrate and a constant potential electrolytic gas sensor having a cell containing an electrolytic solution disposed on one surface of the sensor substrate.
The constant potential electrolytic sensor is provided on one surface of the sensor substrate in a state where there is a gap having a size that causes capillary action between the bottom surface of the cell and one surface of the sensor substrate.
Having a detecting means for detecting leakage of the electrolyte of the constant potential electrolytic gas sensor ,
The detection means is formed in a position immediately below the constant potential electrolytic gas sensor on one surface of the sensor substrate, and is parallel to the first pattern circuit with a gap from the first pattern circuit and the first pattern circuit. The first pattern circuit is formed by a liquid leakage detection circuit having a second pattern circuit formed on the substrate, and the electrolytic solution drops on the sensor substrate and the two pattern circuits are short-circuited. It is characterized in that leakage of the electrolytic solution is detected by detecting that the resistance value between the second pattern circuits decreases.

In the gas detection apparatus of the present invention, the first pattern circuit and the second pattern circuit includes the connection terminal portion of the gas sensing electrode constant potential electrolysis type gas sensor, an outer peripheral edge shape of the constant-potential electrolysis type gas sensor It can be set as the structure formed so that the area | region which followed may be enclosed.

Further, in the gas detection device of the present invention, the liquid leakage detection circuit includes a signal processing circuit formation region formed on a side of the sensor substrate at a position aligned with the sensor placement region in which the constant potential electrolytic gas sensor is placed. It is preferable that the second pattern circuit further includes a third pattern circuit formed in parallel with a distance from the second pattern circuit at a position between the second pattern circuit and the second pattern circuit.

  Furthermore, in the gas detection device of the present invention, it is preferable that the distance between the adjacent pattern circuits is 0.1 to 2.0 mm.

  According to the gas detection device of the present invention, when the electrolyte solution leaking outside from the cell containing the electrolyte solution in the sensor is dropped on the sensor substrate, the droplet of the electrolyte solution is connected to the gas detection electrode. Before contacting the part, the first pattern circuit and the second pattern circuit are short-circuited via the droplet, so that the resistance value between the first pattern circuit and the second pattern circuit is By detecting the decrease, it is possible to reliably detect the leakage of the electrolytic solution, thereby preventing the malfunction and the equipment from being damaged due to the leakage of the electrolytic solution. It is possible to reliably maintain the operation state of the period.

  Further, according to the gas detection device of the present invention, the signal processing circuit formation region formed at a position aligned with the sensor arrangement region on which the sensor is arranged on one surface of the sensor substrate, and the second circuit pattern In the position between the second circuit pattern and the second circuit pattern, the third pattern circuit formed in parallel with the second circuit pattern is further provided, so that the electrolytic solution dropped on the sensor substrate is an electronic component. Further, contact with the signal processing circuit can be prevented in advance, and an intended operation state can be reliably maintained.

The present invention will be described below with reference to the drawings.
The gas detection device of the present invention includes a flat sensor substrate and a gas sensor having an electrolyte solution disposed on one surface of the sensor substrate. Examples of such a gas sensor include a constant potential electrolytic gas sensor and a galvanic cell gas sensor.
In the following, a cell having two openings to be closed by a gas-permeable porous sheet in which an electrolyte solution storage space for containing an electrolyte solution is formed, and a surface of one porous sheet are provided. The working electrode for electrolyzing the gas to be detected and the other porous sheet are provided, the counter electrode for the working electrode, and the other porous sheet are provided separately from the counter electrode to control the potential of the working electrode. An example using a constant potential electrolytic gas sensor having a reference electrode for the purpose will be described.

FIG. 1 is a plan view schematically showing a configuration example of a sensor substrate in the gas detection device of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.
The sensor substrate 10 includes a sensor arrangement region 11A provided with a connection terminal portion 12A related to the working electrode of the constant potential electrolysis gas sensor 15, a connection terminal portion 12B related to the counter electrode, and a connection terminal portion 12C related to the reference electrode, and a constant potential. A potentiostat circuit for maintaining a constant potential between the working electrode and the reference electrode in the electrolytic gas sensor 15 and a gas concentration for detecting the concentration of the gas to be detected based on an output signal obtained from the constant potential electrolytic gas sensor 15 A signal processing circuit forming region 11B in which an electric circuit unit 20 including a detection circuit is formed.

The constant potential electrolytic gas sensor 15 is provided in a state where a gap exists between the bottom surface 16A of the cell 16 and the one surface 10A of the sensor substrate 10. Thereby, as will be described later, for example, when an electrolyte leaking from the side surface of the cell 16 drops on the one surface 10A of the sensor substrate 10 along the side surface of the cell 16, due to the action of the gap (capillary phenomenon), The liquid droplet e of the electrolytic solution can be held on the sensor substrate 10, and the leakage detection circuit 30 can reliably detect that the electrolytic solution has leaked.
Further, the constant potential electrolytic gas sensor 15 is provided in a state in which the edge portion of the sensor substrate 10 protrudes outward from the outer peripheral edge position of the cell 16, and thereby, one surface of the protruding portion of the sensor substrate 10. Functions as a receiver for the electrolyte flowing along the side surface of the cell 16, so that the electrolyte droplet d can be held on the sensor substrate 10 and the leakage of the electrolyte has occurred. 30 can be reliably detected.

In the gas detection device described above, the leakage of the electrolytic solution of the constant potential electrolytic sensor 15 configured by the liquid leakage detection circuit 30 including at least two pattern circuits provided at a predetermined interval from each other is detected. It has a detection means.
The liquid leakage detection circuit 30 according to this embodiment will be described in detail. As shown in FIG. 3, the liquid leakage detection circuit 30 includes a main circuit 31 configured using an operational amplifier 32. The first pattern circuit 33A and the first pattern circuit 33A formed at a position directly below the constant potential electrolytic gas sensor 15 on the one surface 10A are formed in parallel with the first pattern circuit 33A with a space therebetween. The second pattern circuit 33B is connected, and the third pattern circuit 33C formed at a position between the signal processing circuit forming region 11B and the second circuit pattern 33B on the one surface 10A of the sensor substrate 10 is connected. Has been configured.

The first pattern circuit 33A constituting the liquid leakage detection circuit 30 includes, for example, a connection terminal portion 12A related to the working electrode, a counter electrode at a position on the inner side of the position corresponding to the outer peripheral edge position of the potentiostatic gas sensor 15. Is formed in a rectangular frame shape so as to surround a region along the outer peripheral shape of the potentiostatic gas sensor including the connection terminal portion 12B according to the reference electrode and the connection terminal portion 12C according to the reference electrode, and the second pattern circuit 33B For example, in a position corresponding to the outer peripheral edge position of the potentiostatic gas sensor 15, a rectangular frame is formed so as to extend in parallel with the first pattern circuit 33A with a predetermined gap from the first pattern circuit 33A. Is formed.
In addition, the third pattern circuit 33C is formed in a straight line so as to extend in parallel with the linear part in the second pattern circuit 33B with a predetermined gap.

  The size of the separation distance between adjacent pattern circuits constituting the liquid leakage detection circuit 30 is preferably set to 0.1 to 2.0 mm, for example. Thus, the two pattern circuits can be reliably short-circuited via the electrolytic solution droplet e, and it is possible to reliably detect that the electrolytic solution has leaked.

  A configuration example of the liquid leakage detection circuit 30 is as follows. The resistance value of the resistance element R1 is 22 MΩ, the capacitance of the capacitor C1 is 100 pC, the resistance value of the resistance value R3 is 1000 MΩ, the input voltage by the power source V0 is 5 V, and the variable resistance element R2 Of the power supply V2 connected to the positive power supply terminal (+ V) of the operational amplifier is 5V.

  The gas detection operation in the gas detection device having the above-described configuration will be described. A voltage controlled to a predetermined magnitude by the potentiostat circuit is applied to each of the working electrode and the counter electrode in the constant potential electrolytic gas sensor 15, so that the reference electrode A potential difference of a predetermined magnitude is generated between the working electrode and the counter electrode with reference to the potential state of the gas. In this state, the gas to be detected is introduced into the cell through the porous sheet. Each electrolysis current value generated between the electrode and the counter electrode is detected by a potentiostat circuit, and the concentration of the gas to be detected corresponding to the detected electrolysis current value is calculated.

Thus, in the gas detector having the above-described configuration, the resistance value between the first pattern circuit 33A and the second pattern circuit 33B, and the second pattern circuit 33B and the third pattern circuit 33C. The resistance value between them is monitored by the liquid leak detection circuit 30, thereby performing a liquid leak detection operation for detecting whether or not the electrolyte leakage of the constant potential electrolytic gas sensor 15 has occurred.
That is, for example, the electrolyte leaked from the side surface of the cell 16 travels along the side surface of the cell 16 and is on one surface 10A of the sensor substrate 10, specifically, between the first pattern circuit 33A and the second pattern circuit 33B. The first pattern circuit 33A and the second pattern circuit 33B are short-circuited (conducted) via the electrolytic solution droplet e, so that the first pattern circuit 33A and the second pattern circuit 33B are short-circuited with each other. By detecting that the resistance value between the second pattern circuit 33B decreases, it is detected that leakage of the electrolyte has occurred. The same applies to the case where the second pattern circuit 33B and the third pattern circuit 33C are short-circuited via the electrolytic solution droplet e.

  Thus, according to the gas detection device, when the electrolytic solution leaking outside from the cell 16 of the constant potential electrolytic gas sensor 15 is dropped on the sensor substrate 10, the droplet e of the electrolytic solution is applied to the working electrode. Before contacting the connection terminal portion 12A according to the above, the connection terminal portion 12B according to the counter electrode and the connection terminal portion 12C according to the reference electrode, or the electronic component and the signal processing circuit, the first pattern circuit 33A and the second pattern circuit 33B, or between the second pattern circuit 33B and the third pattern circuit 33C is short-circuited (conducted) through the droplet e, so that between two adjacent pattern circuits, For example, by detecting that the resistance value between the first pattern circuit 33A and the second pattern circuit 33B decreases, it is possible to reliably detect that the electrolyte has leaked. Can, thereby, it is possible to reliably maintain the desired operating conditions malfunction or the damage of the equipment caused by can be prevented due to the leakage of the electrolyte.

  Further, since the first pattern circuit 33A and the second pattern circuit 33B are formed at a position directly below the constant potential electrolytic sensor 15 on the one surface 10A of the sensor substrate 10, the pattern circuits 33A and 33B are Since it is not exposed to the outside and is protected from the outside, it is possible to reliably prevent erroneous detection due to foreign matter or the like.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be added.
For example, the liquid leakage detection circuit may have at least two pattern circuits, that is, a first pattern circuit and a second pattern circuit that function as points of interest with respect to the connection terminal portion of each electrode. It is not necessary to have the pattern circuit C.
As described above, the present invention is not limited to a constant potential electrolytic gas sensor, but can be applied to a device using a galvanic cell gas sensor.

It is a top view which shows roughly the example of 1 structure of the sensor board | substrate in the gas detection apparatus of this invention. It is the sectional view on the AA line in FIG. It is a circuit diagram which shows the structure of a liquid leak detection circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sensor board | substrate 10A One surface 11A Sensor arrangement | positioning area | region 11B Signal processing circuit formation area 12A Connection terminal part concerning a working electrode 12B Connection terminal part concerning a counter electrode 12C Connection terminal part concerning a reference electrode 15 Constant potential electrolytic gas sensor 16 Cell 16A Bottom face 20 Electricity Circuit part 30 Liquid leakage detection circuit 31 Main circuit 32 Operational amplifier 33A First pattern circuit 33B Second pattern circuit 33C Third pattern circuit e Liquid droplet of electrolyte

Claims (4)

In a gas detection device comprising a sensor substrate and a constant potential electrolytic gas sensor having a cell containing an electrolytic solution disposed on one surface of the sensor substrate,
The constant potential electrolytic sensor is provided on one surface of the sensor substrate in a state where there is a gap having a size that causes capillary action between the bottom surface of the cell and one surface of the sensor substrate.
Having a detecting means for detecting leakage of the electrolyte of the constant potential electrolytic gas sensor ,
The detection means is formed in a position immediately below the constant potential electrolytic gas sensor on one surface of the sensor substrate, and is parallel to the first pattern circuit with a gap from the first pattern circuit and the first pattern circuit. The first pattern circuit is formed by a liquid leakage detection circuit having a second pattern circuit formed on the substrate, and the electrolytic solution drops on the sensor substrate and the two pattern circuits are short-circuited. A gas detection device characterized in that leakage of an electrolytic solution is detected by detecting a decrease in resistance value between second pattern circuits. The first pattern circuit and the second pattern circuit includes the connection terminal portion of the gas sensing electrode constant potential electrolysis type gas sensor, and is formed so as to surround the region along the outer peripheral edge shape of the constant-potential electrolysis type gas sensor The gas detection device according to claim 1, wherein: The liquid leakage detection circuit is formed between a signal processing circuit formation region formed on a surface of the sensor substrate and aligned with a sensor arrangement region in which a constant potential electrolytic gas sensor is arranged, and the second pattern circuit. 3. The gas detection device according to claim 1, further comprising a third pattern circuit formed at a position in parallel with the second pattern circuit at an interval. 4.   The gas detector according to any one of claims 1 to 3, wherein the distance between adjacent pattern circuits is 0.1 to 2.0 mm.

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