JP2017138220A - Gas sensor and information processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase responses from a gas sensor and heighten sensitivity.SOLUTION: A gas sensor of the present invention is designed to comprise a first detection body 2, a second detection body 3, a first electrode 4 connected to one end of the first detection body and second detection body, a second electrode 5 connected to the other ends of the first detection body and second detection body, a first intermediate electrode 6 provided in the middle of the first detection body, a second intermediate electrode 7 provided in the middle of the second detection body, a first covering part 8 for covering a portion from the first electrode of the first detection body to the first intermediate electrode, and a second covering part 9 for covering a portion from the second electrode of the second detection body to the second intermediate electrode, the first intermediate electrode and the second intermediate electrode being out of alignment with each other along the length direction of the first detection body and second detection body extending between the first electrode and the second electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas sensor and an information processing system.

Conventionally, gas sensors generally used include a type in which a solid electrolyte is disposed between electrodes and a potential difference is measured, or a substance whose electrical resistance changes by contact with a target gas (for example, an oxide semiconductor). There is a resistance change type that uses the sensor for the detection body.
Each of these types has advantages, but a reference electrode is not required, and a simpler resistance change type is widely used.

The principle of operation of the resistance change type gas sensor utilizes the fact that the concentration of carriers (electrons or holes) in the detection body in contact with the detection target gas changes.
That is, there is a one-to-one relationship between the concentration of the gas to be detected in the atmosphere and the amount of gas to be detected per unit area of the surface of the detection body. Since the one-to-one relationship is established between the resistances, the concentration of the detection target gas can be known by observing a change in the electrical resistance.

The response of the resistance change type gas sensor may be observed as a change in resistance. For example, as shown in FIG. 10, a fixed resistor is connected in series to a detector functioning as a variable resistor, and a constant voltage is applied to the whole. Thus, the potential difference between the terminals at both ends of the detection body may be observed, and the measurement of the potential difference is easier in practical use.
Further, in the configuration for converting the resistance change as described above into the potential difference change, in order to improve the linearity of the response and perform the measurement more accurately, the structure in which the detector and the fixed resistor are connected in series is connected in parallel. There has also been proposed a technique of adding a potential difference between terminals of a detector or calculating an average.

JP-A-55-137334 JP 62-174644 A JP 2005-24513 A JP 2004-85549 A JP-A 63-66449

However, the resistance change rate of the material used for the detector of the conventional resistance change type gas sensor is about several percent when the concentration of the detection target gas is on the order of ppm. For example, the concentration of the metabolism-related gas species contained in the exhalation ( It is difficult to deal with (ppb order).
It is an object of the present invention to increase the response of a gas sensor and increase the sensitivity.

  In one aspect, the gas sensor includes a first detector, a second detector, a first electrode connected to one end of the first detector and the second detector, a first detector, and a second detector. A second electrode connected to the other end of the detector, a first intermediate electrode provided in the middle of the first detector, a second intermediate electrode provided in the middle of the second detector, and a first A first covering portion that covers a portion from the first electrode of the detector to the first intermediate electrode; and a second covering portion that covers a portion of the second detector from the second electrode to the second intermediate electrode; The first intermediate electrode and the second intermediate electrode are displaced from each other along the length direction of the first detector and the second detector extending between the first electrode and the second electrode.

In one aspect, an information processing system includes the gas sensor described above and a computer that processes data obtained by the gas sensor.
In one aspect, an information processing system includes the above-described gas sensor and a computer that processes data obtained by the gas sensor, and the gas sensor has a first electrode connected to one end of the first detector. A first detection body including a first detection body side portion and a second detection body side portion connected to one end of the second detection body, wherein the second electrode is connected to the other end of the first detection body; A body-side portion and a second detector-side portion connected to the other end of the second detector, and the first electrode is switched between connection / disconnection between the first detector-side portion and the second detector-side portion. A first changeover switch, and a second changeover switch for switching connection / disconnection between the first detection body side portion and the second detection body side portion of the second electrode, and the computer uses the first changeover switch to switch the first electrode of the first electrode. Non-detector side and second detector side In the state where the first detector body side portion and the second detector body side portion of the second electrode are disconnected by the second changeover switch, the first electrode is at a low potential in the first detector body and the second detector body. Side, the potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a forward voltage so that the second electrode is on the high potential side, and the first detector and the second detector The potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a reverse voltage so that the first electrode is on the high potential side and the second electrode is on the low potential side, and the first detector And a calibration unit that calibrates the measured value using the entire resistance value of the second detector.

  As one aspect, there is an effect that the response of the gas sensor can be increased and high sensitivity can be achieved.

It is a typical top view showing composition of a gas sensor device with which a gas sensor concerning this embodiment is provided. It is a typical top view showing composition of a gas sensor device with which a gas sensor concerning this embodiment is provided. In the gas sensor device provided in the gas sensor according to the present embodiment, the resistances per unit length of the covering regions and the non-covering regions of the respective detection bodies are equal, and x / l = 0.5 and y / x = 0. is a diagram illustrating the relationship between the rate of change of the potential difference of the resistance change rate and the intermediate electrode uncoated region when it is .45 (V 2 _{-V 1).} In the gas sensor device provided in the gas sensor according to the present embodiment, the ratio of the change rate of the potential difference (V ₂ −V ₁ ) of the intermediate electrode obtained by the combination of x / l and y / l to the resistance change rate of the uncovered region FIG. It is a schematic diagram for demonstrating the structure and calibration method when calibrating in the gas sensor concerning this embodiment, Comprising: It is a figure which shows the case where the connection direction with a power supply is a forward direction. It is a schematic diagram for demonstrating the structure and calibration method when calibrating in the gas sensor concerning this embodiment, Comprising: It is a figure which shows the case where the connection direction with a power supply is a reverse direction. It is a flowchart which shows the calibration procedure in the gas sensor concerning this embodiment. It is a mimetic diagram showing the example of composition of the information processing system concerning this embodiment. It is a mimetic diagram showing the example of composition of the information processing system concerning this embodiment. It is a figure which shows the typical circuit structure which converts the response signal of a resistance change type gas sensor into a voltage signal. In the structure shown in FIG. 10, it is a figure which shows the relationship between the resistance change rate and potential difference change rate of a detection body when a fixed resistance value is 10 times the resistance value of the detection body in a non-contact state with gas. In the structure shown in FIG. 10, it is a figure which shows the relationship between ratio of a fixed resistance value, the resistance value of the detection body in a non-contact state with gas, and a potential difference change rate when the resistance value of a detection body increases 10%. .

Hereinafter, a gas sensor and an information processing system according to an embodiment of the present invention will be described with reference to FIGS.
The gas sensor according to the present embodiment is a resistance change type gas sensor, which is a gas sensor that detects (measures) a chemical substance in the atmosphere, and particularly, is included in human exhaust gas including human exhalation and reflects the health condition. It is a highly sensitive gas sensor that detects chemical substances.

As shown in FIG. 1, the gas sensor according to the present embodiment includes a gas sensor device 1, and the gas sensor device 1 includes a first detector 2, a second detector 3, a first electrode 4, and a second electrode 5. A first intermediate electrode 6, a second intermediate electrode 7, a first covering portion 8, and a second covering portion 9.
Here, the first detector 2 and the second detector 3 are gas detectors that detect the detection target gas.

The material (detection material) used for the first detector 2 and the second detector 3 is not limited in principle.
However, it is important to monitor health status by using a detection material that strongly responds to ammonia, which is important as an index related to health status, among metabolism-related substances contained in human breath. It is possible to realize a sensor device that plays a role.

For this reason, it is preferable to use a detection material that strongly responds to ammonia in order to take advantage of the high sensitivity.
Here, as a specific example of the detection material showing a strong response to ammonia, copper bromide (I) (CuBr; cuprous bromide) and copper oxide (I) (Cu ₂ O; which are p-type semiconductors) are used. Cuprous oxide), copper sulfide (I) (Cu ₂ S; cuprous sulfide), silver oxide (Ag ₂ O), silver bromide (AgBr), silver sulfide (Ag ₂ S), etc. A compound can be mentioned.

Thus, the first detector 2 and the second detector 3 are preferably copper or silver compounds, and in particular, cuprous bromide, cuprous oxide, cuprous sulfide, silver oxide, odor, It is preferably any one selected from the group consisting of silver halide and silver sulfide. Silver halide and copper halide may be used.
Here, two detection bodies having the same configuration are used as a pair for the first detection body 2 and the second detection body 3.

The first electrode 4 is connected to one end of the first detector 2 and the second detector 3, and the second electrode 5 is connected to the other end of the first detector 2 and the second detector 3. Is connected. And the 1st electrode 4 and the 2nd electrode 5 are connected to the power supply (here constant voltage power supply) 10 as shown in FIG.
That is, the first electrode 4 and the second electrode 5 connected to the power source 10 are connected to both ends of the first detector 2 and the second detector 3, and the first detector 2 and the second detector 3 are Connected in parallel.

Here, the first electrode 4 is connected to the low voltage side (here, ground; GND) of the power supply 10, and the second electrode 5 is connected to the high voltage side (here, V ₀ ) of the power supply 10. Yes. For this reason, the 1st electrode 4 is also called a low voltage side electrode, and the 2nd electrode 5 is also called a high voltage side electrode. The constant voltage power source is also referred to as a constant voltage current source. In addition, the first electrode 4 and the second electrode 5 are electrodes connected to the power supply 10 and are also referred to as power supply connection electrodes.

A first intermediate electrode 6 is provided in the middle of the first detector 2, and a second intermediate electrode 7 is provided in the middle of the second detector 3. Then, by detecting the potential difference between the first intermediate electrode 6 and the second intermediate electrode 7, the detection target gas is detected (detection operation).
The first intermediate electrode 6 and the second intermediate electrode 7 are electrodes used for measuring a potential difference (that is, a potential difference corresponding to a resistance change between the first detector 2 and the second detector 3). Also called measurement electrode.

Further, a portion from the first electrode 4 to the first intermediate electrode 6 of the first detector 2 is covered with the first covering portion 8, and from the second electrode 5 to the second intermediate electrode 7 of the second detector 3. Is covered with the second covering portion 9. The covering portion is also called a cover.
In addition, these coating | coated parts 8 and 9 should just cover the detection bodies 2 and 3 so that detection object gas may pass and may not contact the detection bodies 2 and 3, There is no restriction | limiting in particular in the material, For example, organic A material may be sufficient and an inorganic material may be sufficient. Moreover, it is preferable that the material of these coating | coated parts 8 and 9 is an insulating material.

In this way, one intermediate electrode 6, 7 is provided in the middle of each detector 2, 3. And one 1st detection body 2 is a 1st coating | coated part so that it may not contact the detection object gas from the 1st electrode 4 connected to the low voltage side of the power supply 10 to the intermediate electrode 6 provided in the middle. 8 is covered.
The other second detection body 3 includes a second covering portion so that the second electrode 5 connected to the high voltage side of the power source 10 and the intermediate electrode 7 provided in the middle thereof do not contact the detection target gas. 9 is covered.

In particular, the first intermediate electrode 6 and the second intermediate electrode 7 extend along the length direction of the first detector 2 and the second detector 3 that extend between the first electrode 4 and the second electrode 5. , They are out of position with each other. Thereby, it has a signal amplification function substantially, and it becomes possible to increase the response of the gas sensor device 1, and consequently the gas sensor, and to achieve high sensitivity.
In particular, the distance between the first electrode 4 and the first intermediate electrode 6 is x, and the length of the region where the first intermediate electrode 6 is provided from the distance between the first electrode 4 and the second electrode 5. Is 1 and the distance between the second electrode 5 and the second intermediate electrode 7 is y, 9.5 / (0.6+ (x / l)) − 5.8 <y It is preferable that the positions of the first intermediate electrode 6 and the second intermediate electrode 7 are set so as to satisfy the relationship of /l<0.98-0.95 (x / l) ² . Accordingly, the signal amplifying function is surely provided, and the response of the gas sensor device 1 and, consequently, the gas sensor can be increased to achieve high sensitivity.

  Here, since the portion from the first electrode 4 to the first intermediate electrode 6 of the first detector 2 is covered by the first covering portion 8, the distance x is covered by the first covering portion 8. This is the distance between the first electrode 4 (low potential side electrode) and the first intermediate electrode 6 in the region. The distance l is a length obtained by subtracting the length overlapping the first intermediate electrode 6 from the length of the region sandwiched between the first electrode 4 and the second electrode 5 of the first detector 2. Moreover, since the part from the 2nd electrode 5 of the 2nd detection body 3 to the 2nd intermediate electrode 7 is coat | covered with the 2nd coating | coated part 9, distance y is the area | region covered with the 2nd coating | coated part 9. This is the distance between the second electrode 5 (high potential side electrode) and the second intermediate electrode 7.

In the present embodiment, in addition to the gas sensor device 1 configured as described above, the gas sensor includes, as shown in FIG. 2, the potential of the first intermediate electrode 6, the potential of the second intermediate electrode 7, and the first A potentiometer 11 that measures the potential difference between the potential of the intermediate electrode 6 and the potential of the second intermediate electrode 7 is provided.
In the present embodiment, the gas sensor includes a constant voltage power source that supplies a constant voltage between the first electrode 4 and the second electrode 5 as the power source 10 in addition to the gas sensor device 1 configured as described above. .

Note that the gas sensor may be configured not to include the potentiometer 11 and the power source 10, and a potentiometer and a power source (external power source) provided separately from the gas sensor may be connected to the gas sensor (gas sensor device 1). .
By the way, the reason for the above configuration is as follows.
Many materials other than oxide semiconductors can be used for the sensing element (gas sensing element) of a resistance change type gas sensor, and various types of gas can be detected by appropriately selecting the material according to the purpose. Can be performed.

However, in most cases, the resistance change rate of the material used for the detection body is about several percent when the concentration of the detection target gas is on the order of ppm. For example, the concentration of the metabolism-related gas species contained in the exhalation (ppb order) It is difficult to deal with
For this reason, the applied voltage is increased in order to increase the absolute value of the resistance change amount, but there is a restriction on the range of the applied voltage that can be applied in terms of both the characteristics of the material used for the detector and the current consumption.

In addition, the upper limit of the resistance value of the detection body may be limited by the input impedance of a device (potentiometer) that measures the potential difference.
The lower limit of detection as a gas sensor is determined by these constraints and the measurement resolution of the device that measures the potential difference. Therefore, in order to improve the sensitivity of the gas sensor, the detection response characteristics of the material itself used for the sensing element can be improved. There is no choice but to change it to an excellent one.

In the typical configuration shown in FIG. 10, the magnitude of the potential difference signal changes depending on the relationship between the fixed resistance and the range in which the resistance value of the detection body can take, but the resistance change rate of the detection body and the potential difference signal There are certain restrictions on the relationship with the rate of change.
First, in the case of the configuration shown in FIG. 10, the following relationship is established between the potential difference signal and the resistance value of the detection body.

Observed potential difference = V × resistance value of detection object / (fixed resistance value + resistance value of detection object) (1)
Here, FIG. 11 shows the resistance change rate of the detection body when the resistance value (fixed resistance value) of the fixed resistance is 10 times the resistance value of the detection body when the detection body is not in contact with the gas. And the potential difference change rate.

As shown in FIG. 11, when the resistance value of the fixed resistor is higher than the resistance value of the detection body, the potential difference change rate is close to linear with respect to the resistance change rate of the detection body.
As shown in FIG. 12, the upper limit of the ratio of the potential difference change rate to the resistance change rate of the detector is 1.
In reality, in order to accurately measure the potential difference, the resistance value of the fixed resistor needs to be made considerably smaller than the input impedance of the device for measuring the potential difference (potential difference measuring device), so the potential difference change rate is detected. The measurement is performed under a condition that is somewhat smaller than the resistance change rate of the body.

Therefore, the above-described configuration is adopted in order to increase the response of the gas sensor and increase the sensitivity without changing the material used for the detection body with a simple configuration.
By the way, when calibrating the gas sensor device 1 as will be described later, the gas sensor device 1 and the gas sensor including the gas sensor device 1 are preferably configured as follows.
That is, as shown in FIGS. 5 and 6, the first electrode 4 of the gas sensor device 1 is connected to the first detection body side portion 4 </ b> A connected to one end of the first detection body 2 and the second detection body 3. The second detector 5 is provided with a second detector-side portion 4B connected to one end, and the second electrode 5 is connected to the other end of the first detector 2 with a first detector-side portion 5A and a second The second detection body side portion 5B connected to the other end of the detection body 3 is provided, and the connection / disconnection between the first detection body side portion 4A and the second detection body side portion 4B of the first electrode 4 is switched. It is preferable to include a first changeover switch 12 and a second changeover switch 13 that switches connection / disconnection between the first detector-side portion 5A and the second detector-side portion 5B of the second electrode 5. Thereby, when calibrating the gas sensor device 1, it becomes possible to apply a voltage independently from the electrodes 4A, 4B, 5A, and 5B provided at both ends of each of the detection bodies 2 and 3.

  Then, in the gas sensor, the first detection body side portion 4A and the second detection body side portion 4B of the first electrode 4 are disconnected from each other by the first changeover switch 12, and the first changeover of the second electrode 5 by the second changeover switch 13 is performed. In a state where the detection body side portion 5A and the second detection body side portion 5B are not connected, the first electrode 4 is connected to the first detection body 2 and the second detection body 3, and the second electrode 5 is connected to the high potential side. The potential of the first intermediate electrode 6 and the potential of the second intermediate electrode 7 measured by applying a forward voltage so that the first electrode 4 is higher than the first detector 2 and the second detector 3. The potential of the first intermediate electrode 6 and the potential of the second intermediate electrode 7 measured by applying a reverse voltage so that the second electrode 5 is on the lower potential side, and the first detector 2 and Calibration unit 1 that calibrates the measured value using the entire resistance value of the second detector 3 Preferably those with a.

As described above, the potentials of the intermediate electrodes 6 and 7 when a forward voltage is applied to the detectors 2 and 3 and the potentials of the intermediate electrodes 6 and 7 when a reverse voltage is applied. It is preferable to calibrate the measured value of the gas sensor device 1 using the entire resistance value of the first detector 2 and the second detector 3.
In this case, the gas sensor may be provided with a computer 21 including, for example, a processor such as the CPU 20 in addition to the gas sensor device 1 configured as described above. Then, the measurement value measured by the gas sensor device 1 may be calibrated by the computer 21 connected to the gas sensor device 1. In this case, the computer 21 provided in the gas sensor has a function as the calibration unit 14 described above.

Here, the gas sensor includes the calibration unit 14, but the present invention is not limited to this. For example, a computer connected to the gas sensor may include the calibration unit 14.
That is, as shown in FIG. 8, the gas sensor 15 including the above-described gas sensor device 1 is connected to a computer 16 such as a personal computer so that the measurement value measured by the gas sensor 15 is sent to the computer 16. The measured value measured by the gas sensor 15 may be calibrated by the computer 16 connected to the.

In addition, data (information) obtained by the gas sensor 15 may be processed by the computer 16 so that an index indicating the concentration of the chemical substance or the presence or absence of a disease is displayed on the screen of the computer 16.
In this case, an information processing system 19 that performs such data processing (information processing) includes a gas sensor 15 including the gas sensor device 1 described above, and a computer 16 that is connected to the gas sensor 15 and processes data obtained by the gas sensor 15. It will be equipped with.

  Further, as shown in FIG. 9, the gas sensor 15 including the gas sensor device 1 configured as described above is connected to a computer 18 such as a server connected via a network 17 and measured by the gas sensor 15. The measurement value may be sent to the computer 18, and the measurement value measured by the gas sensor 15 may be calibrated by the computer 18 connected to the gas sensor 15.

In addition, data (information) obtained by the gas sensor 15 can be collected and accumulated via the network 17 to construct a database, analyze these data, and feed back the results. is there.
As a result, it can be used effectively for improving screening accuracy of diseases, investigating the presence or absence of correlation with other diseases, etc., and it is possible to feed back measurement results without much effort. It becomes. For example, by analyzing the presence or absence of cancer in the breath measurement subject or the correlation with other diseases, it is possible to improve screening accuracy and develop for screening for other diseases.

In this case, the information processing system 19 that performs such data processing (information processing) is connected to the gas sensor 15 including the gas sensor device 1 described above and the gas sensor 15 via the network 17, and the data obtained by the gas sensor 15 is processed. A server (computer) 18 for processing is provided.
Hereinafter, the operation of the gas sensor of this embodiment will be described.

Here, the potential difference between the electrodes provided at both ends of the first detector 2 and the second detector 3 provided in the above-described gas sensor is represented by V ₀ and the distance between the electrodes at both ends of the first detector 2 as the first intermediate electrode. The distance obtained by subtracting the length overlapping 6 is defined as l, and the distance obtained by subtracting the length overlapping the second intermediate electrode 7 from the distance between the two end electrodes of the second detector 3 is defined as l ′. In addition, since the detection bodies 2 and 3 work as variable resistors, they are also referred to as resistors.

In the first detector 2, the resistance per unit length in the first covering portion 8 is R ₁ , the distance from the first electrode 4 to the first intermediate electrode 6 is x, and the potential of the first intermediate electrode 6 is V _1. A resistance per unit length of a portion not covered by the first covering portion 8 (non-covered portion) is defined as R.
In the second detector 3, the resistance per unit length in the second covering portion 9 is R ₂ , the distance from the second electrode 5 to the second intermediate electrode 7 is y, and the potential of the second intermediate electrode 7 is V _2. The resistance per unit length of the portion not covered by the second covering portion 9 (non-covered portion) is defined as R ′.

Here, the portions covered by the first covering portion 8 and the second covering portion 9 of the first detecting body 2 and the second detecting body 3 do not come into contact with the outside air, so that R ₁ and R ₂ are changed. Instead, these parts act as fixed resistors.
For this reason, R and R ′ change due to contact with the detection target gas, and as a result, an operation is performed in which V ₁ and V ₂ change.

  At this time, the potential difference between the intermediate electrodes is described as follows.

As is clear from the definition, ideally, l = 1 ′, R = R ′, and R ₁ = R ₂ .
For example, FIG. 3 shows the rate of change of R (and R ′) when l = l ′, R = R ′, R ₁ = R ₂ , x / l = 0.5, y / l = 0.45 ( The relationship between the resistance change rate) and the change rate of V ₂ −V ₁ (potential difference change rate) is shown.
As shown in FIG. 3, when the rate of change of R is about 20% or less, V ₂ -V ₁ and R are almost linear with each other, and the rate of change of V ₂ -V ₁ is 9 times or more of the rate of change of R. .

The relationship between the rate of change of the resistance (R, R ′) of the detector and the rate of change of V ₂ −V ₁ varies depending on the relationship of l, l ′, R, R ′, R ₁ , R _2. It is difficult to analytically find the relationship from equation (2).
Therefore, for the ideal case where l = l ′, R = R ′, and R ₁ = R ₂ , the ratio of the change rate of V ₂ −V ₁ corresponding to the combination of x and y to the change rate of R is This is shown in FIG.

The value of the ratio shown in FIG. 4 is an average value of results obtained when the rate of increase in resistance of the non-covered portion (non-covered region) is 1 to 50%.
If the above ratio is 2 or more, the two sensing bodies are used in the typical configuration shown in FIG. 10, and a potential difference signal having a magnitude exceeding the upper limit when the obtained signals are added can be obtained. Therefore, such a case is shown in bold.

In other words, in the range where the numerical values are shown in bold in FIG. 4, the above-described gas sensor substantially has a signal amplification function. In FIG. 4, the range indicated in bold is roughly 9.5 / (0.6+ (x / l)) − 5.8 <y / l <0.98−0.95 (x / l) ² . Can be represented. By definition, x / l <1 and y / l <1. Further, when strictly x / l = 1−y / l, that is, when the positions of the first intermediate electrode 6 and the second intermediate electrode 7 coincide with each other in the length direction of the detector, V ₂ −V ₁ becomes 0, and the rate of change of V ₂ −V ₁ with respect to the rate of change of resistance of the non-covered portion diverges, which is not applicable.

Thus, the first intermediate electrode 6 and the second intermediate electrode 7 are arranged in the length direction of the first detector 2 and the second detector 3 extending between the first electrode 4 and the second electrode 5. Accordingly, since the positions are shifted from each other, the signal amplifying function is substantially provided, the response of the gas sensor is increased, and high sensitivity can be achieved.
By the way, in the manufacture of devices, there are certain processing errors and variations in material properties, so in reality, the device is used in a state deviating from the above ideal conditions.

As can be easily understood from FIG. 4, when x / l and 1−y / l are close, a large amplification effect is exhibited, which is V ₂ with respect to the resistance change rate of the uncovered portion. It also means that the change rate of −V ₁ is close to the diverging condition, and is strongly influenced by the deviation of the values of x / l and 1−y / l due to manufacturing errors.
Such errors caused by manufacturing errors can be minimized by calibrating by means described below.

In this case, the gas sensor device 1 has a configuration in which the electrodes 4 and 5 at both ends of the two detection bodies 2 and 3 are divided and the portions provided on the detection bodies 2 and 3 are independent (FIGS. 5 and 6). reference).
First, as shown in FIG. 5, the power supply 10 is connected with the polarity set to the forward direction, the change-over switches 12 and 13 are disconnected, and the detectors 2 and 3, for example, in clean air or pure nitrogen, are connected. the resistivity of the uncoated portion, under conditions which can be regarded as invariant to cover part 8,9, the potential V ₂ of the potentials V ₁ and second intermediate electrode 7 of the first intermediate electrode _6, further each of the detection object 2 3 is measured. At this time,

Since the denominator of the above formula (3) is the entire resistance value of the left first detection body 2 in FIG. 5, the resistance value xR of the covered portion of the first detection body 2 using this is used. ₁ is calculated.
Next, as shown in FIG. 6, the power supply 10 is connected with the polarity reversed, and the change-over switches 12 and 13 are disconnected. Similarly, the potential V ′ ₁ and the second potential of the first intermediate electrode 6 The potential V ′ ₂ of the intermediate electrode 7 is measured. At this time,

Since the denominator of the above formula (6) is the entire resistance value of the second detection body 3 on the right side in FIG. 6, the resistance value yR of the covered portion of the second detection body 3 using this. ₂ is calculated.
Next, when the ratio between V ₂ in the above formula (4) and V ′ _{1 in the} above formula (5) is calculated, these ratios are expressed by the following formula (7).

  The right side of the above (7) is the ratio of the denominator of the above equation (4) to the denominator of the above equation (5), that is, the entire resistance value of the right second detector 3 in FIG. 6 and the left first detector. 2 and the resistance of the uncovered portion (non-covered portion) of the second detector 3 on the right side in FIG. 6 and the uncovered portion of the first detector 2 on the left side. It is the product of the ratio of the resistance of the part (uncovered part). The former is the ratio between the known overall resistance value of the second sensing element 3 and the overall resistance value of the first sensing element 2. That is, from Equation (7), this ratio is equal to the resistance of the uncovered portion (uncovered portion) of the right second detector 3 in FIG. It can be seen that the coefficient is proportional to the resistance of the non-covered part (uncovered part).

If this proportionality coefficient is expressed as α, the overall resistance value of the left first detection body 2 in FIG. 5 is expressed as β, and the overall resistance value of the right first detection body 2 is expressed as γ, V used for the gas detection operation ₂ -V ₁ is the resistance value of the non-coated portion as a linear function of the parameters, is described by the following equation (8).

On the other hand, when the device is ideally manufactured, V ₂ −V ₁ is represented by the following formula (9) using the same β and γ as the above formula (8).
Since the second term on the right side of the above equation (8) and the following equation (9) is the same constant, the difference between these functions is only the coefficient α of the first term, and thus was observed in the fabricated device. By multiplying the slope of V ₂ −V ₁ with respect to the change of R by the reciprocal of α, it is possible to convert the response to what should be obtained when the device is ideally fabricated.

In addition, each of the gas mixtures containing the detection target gases with different concentrations and separately measured, each obtained by using a calibration curve showing the relationship between the resistance value of the detection material and the concentration of the detection target gas. From the R corresponding to the gas concentration and the observed slope and intercept of V ₂ −V ₁ , α in the above equation (8) and the second term that is a constant may be calculated.
Then, ideally using the observed potential difference V ₂ −V ₁ , the calculated α, and the second term (denoted as δ) of the above equation (8) (and the above equation (9)). V ₂ −V ₁ (denoted as dVi) that should be observed when fabricated can be calculated by the following equation (10).

dVi = (V ₂ −V ₁ ) / α + δ / α−δ (10)
In this way, the observed potential difference, which is a measurement value measured by the gas sensor device 1, can be calibrated.
In short, the observed potential difference can be calibrated by the following procedure.
First, connect the power source 10 in the forward direction (see FIG. 5), the overall resistance value of the potential V _2, 2 two sensing elements 2, 3 of the potentials V ₁ and second intermediate electrode 7 of the first intermediate electrode 6 Measurement is performed (step S1 in FIG. 7).

Next, connect the power source 10 in the opposite direction (see FIG. 6), the _{2 'potential} V ₁ and the second intermediate electrode _7' potential V of the first intermediate electrode 6 is measured (step S2 in FIG. 7).
Then, when the power source 10 is connected in the forward direction (see FIG. 5), the potential V ₁ of the first intermediate electrode 6 and the entire resistance value of the first detector 2 are used to cover the first detector 2. calculating a resistance value xR ₁ part (coated region). Further, when the power source 10 is connected in the reverse direction (see FIG. 6), the potential V ′ ₂ of the second intermediate electrode 7 and the entire resistance value of the second detector 3 are used to cover the second detector 3. portion calculates the resistance value yR ₂ of (coated region) (step S3 in FIG. 7). The respective resistance values may be calculated in steps S1 and S2 in FIG.

Next, calibration curves corresponding to uncovered portions (non-covered regions) of the two detectors 2 and 3 are created using a plurality of gases having different concentrations (step S4 in FIG. 7).
Then, when connecting power source 10 to the forward potential of the first intermediate electrode 6 in the case of connecting the second intermediate electrode 7 potential V ₂ and the power source 10 in the opposite direction (see FIG. 5) (see FIG. 6) from the ratio of the V _'1, to calculate the α is the ratio of the resistance value of the non-covered area (step S5 in FIG. 7).

Next, V ₂ -V ₁ is measured using a plurality of gases having different concentrations to obtain δ (step S6 in FIG. 7).
It should be noted that calibration curves corresponding to the uncovered portions (non-covered regions) of the two detectors 2 and 3 are created using a plurality of gases having different concentrations, and R and V ₂ −V corresponding to the respective gas concentrations. Α and δ may be obtained from the slope of ₁ and the intercept.

Then, the observed potential difference V ₂ −V ₁ is calibrated using α and δ (step S7 in FIG. 7).
By performing calibration in this manner, it is possible to maintain measurement accuracy even when the gas sensor device 1 is removed from the gas sensor and replaced.
By the way, when using a detection material in which the response intensity with respect to the concentration of the detection target gas (measurement target gas) tends to vary, it is preferable to correct the response to the gas concentration for each detection object.

In this case, in addition to calibration of errors caused by manufacturing errors performed in the above procedure, the right and left detectors 2 and 3 in FIG. 5 are independently formed as sensor devices having the same configuration as that shown in FIG. It is desirable to create a calibration curve that shows the relationship between the resistance values (R, R ′) of the respective uncovered regions and the concentration of the observation target gas.
In these methods, the resistance value of the covered region is calculated by the above-described method, and those values are substituted into the fixed resistance value in the above equation (1), and several gas mixtures containing detection target gases having different concentrations are obtained. And obtained by measuring the potential difference between the intermediate electrode and the reference electrode (GND).

Of the electrodes connected to the left detection body 2 in FIG. 5, if the upper side is GND, the lower side is V _0, and the connection to the right detection body 3 is left as it is, the same configuration as that shown in FIG. Since there are two sensor devices, measurement may be performed with such a configuration.
Therefore, the gas sensor and the information processing system according to the present embodiment have an effect that the response of the gas sensor can be increased and the sensitivity can be increased.

  That is, as described above, both ends of the electrodes 4 and 5 and the intermediate electrodes 6 and 7 are used, and a pair of detectors 2 and 3 connected in parallel is used. To the intermediate electrode, and the other is covered from the high-potential side electrode to the intermediate electrode of both end electrodes, and by observing the potential difference between the intermediate electrodes, a large response signal can be obtained at a minute concentration, By performing appropriate calibration and correction, it is possible to know the original resistance change rate of the detection body. That is, an effect of substantially lowering the detection lower limit can be obtained without changing the detection material.

  Furthermore, since the covered area used for fixed resistance and the uncovered area used for measurement are made of the same material, the temperature dependence of the resistance is the same except for changes corresponding to contact with the outside air. In principle, it is possible to suppress the temperature drift smaller than when a resistor is separately prepared and connected.

Hereinafter, it demonstrates still in detail according to an Example. However, the present invention is not limited to the following examples.
In this example, first, a distance is formed on a silicon wafer (substrate) with a thermal oxide film having a thermal oxide film (SiO ₂ film; insulating film) having a length of about 50 mm and a width of about 10 mm and a thickness of about 1 μm on the surface. Two gold electrodes (a pair of gold electrodes; gold electrode film) having a width of about 20 mm, a length of about 20 mm, and a film thickness of about 60 nm were formed by vacuum deposition using a mask with a gap of about 5 mm interposed therebetween. In this way, the first electrode 4 and the second electrode 5 were formed (see, for example, FIG. 1).

Subsequently, two copper patterns having a thickness of about 60 nm and a plane shape of about 5 mm in width and a thickness of about 20 mm are arranged in parallel at an interval of about 5 mm by vacuum deposition using a mask. Formed.
Subsequently, it was immersed in a cupric bromide aqueous solution having a concentration of about 100 mM for about 18 seconds. This treatment changed the copper film to a cuprous bromide (CuBr) film having a thickness of about 300 nm.

Thus, the 1st detection body 2 and the 2nd detection body 3 were formed (for example, refer FIG. 1).
Next, two gold electrodes having a width of about 2 mm, a length of about 15 mm, and a thickness of about 60 mm are formed on the CuBr film by vacuum deposition using a mask in the gap provided between the gold electrodes. It was formed so as to cross the membrane.
Thus, the 1st intermediate electrode 6 and the 2nd intermediate electrode 7 were formed (for example, refer FIG. 1). Here, the gold electrode as the first intermediate electrode 6 and the second intermediate electrode 7 is formed on the CuBr film as the first detector 2 and the second detector 3, but it is shown in FIG. As described above, a gold electrode as the first intermediate electrode 6 and the second intermediate electrode 7 may be formed under the CuBr film as the first detector 2 and the second detector 3.

Here, one of the gold electrodes as the intermediate electrode formed on the CuBr film is made of a heat-resistant resin on this region with the distance from the electrode used as the low potential side of both end electrodes 4 and 5 being about 1.2 mm. A pressure-sensitive adhesive tape was applied to perform coating. In this case, the distance from the electrode used as the high potential side is about 1.8 mm, and x / l = 0.4.
Also, the other of the gold electrodes as the intermediate electrode formed on the CuBr film is coated with a distance of about 1.5 mm from the electrode used as the high potential side, and a heat-resistant resin adhesive tape is applied on this region. I did it. In this case, the distance from the electrode used as the low potential side is about 1.5 mm, and y / l = 0.5.

Thus, the 1st coating | coated part 8 and the 2nd coating | coated part 9 were formed (for example, refer FIG. 1).
The gas sensor device thus manufactured is held in nitrogen gas having a flow rate of about 4 L / min, and the response to ammonia is performed by switching to nitrogen containing about 10 ppb of ammonia having a flow rate of about 4 L / min. Evaluated.
Under this condition, the rate of change in resistance of the uncoated portion was about 12% about 5 minutes after the start of exposure to the ammonia-containing gas, whereas the change in potential difference between the intermediate electrodes was about 53%. As a result, an amplification effect of about 4.4 times was obtained.

In addition, this invention is not limited to the structure described in embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
Hereinafter, additional notes will be disclosed regarding the above-described embodiment.
(Appendix 1)
A first detector;
A second detector;
A first electrode connected to one end of the first detector and the second detector;
A second electrode connected to the other end of the first detector and the second detector;
A first intermediate electrode provided in the middle of the first detector;
A second intermediate electrode provided in the middle of the second detector;
A first covering portion that covers a portion from the first electrode to the first intermediate electrode of the first detector;
A second covering portion covering a portion from the second electrode to the second intermediate electrode of the second detector;
The first intermediate electrode and the second intermediate electrode are arranged along the length direction of the first detector and the second detector extending between the first electrode and the second electrode. A gas sensor characterized by being displaced.

(Appendix 2)
And a potentiometer that measures a potential of the first intermediate electrode, a potential of the second intermediate electrode, and a potential difference between the potential of the first intermediate electrode and the potential of the second intermediate electrode. The gas sensor according to appendix 1.
(Appendix 3)
The gas sensor according to appendix 1 or 2, further comprising a constant voltage power source that supplies a constant voltage between the first electrode and the second electrode.

(Appendix 4)
The distance between the first electrode and the first intermediate electrode is x, and the length of the region where the first intermediate electrode is provided is subtracted from the distance between the first electrode and the second electrode. 9.5 / (0.6+ (x / l)) − 5.8 <y / l where l is the distance and y is the distance between the second electrode and the second intermediate electrode. <0.98-0.95 (x / l) ^{2 The position} of the said 1st intermediate electrode and the said 2nd intermediate electrode is set so that the relationship of ² may be satisfy | filled, The gas sensor according to any one of claims.

(Appendix 5)
The gas sensor according to any one of appendices 1 to 4, wherein the first detector and the second detector are copper or silver compounds.
(Appendix 6)
The first detector and the second detector include any one selected from the group consisting of cuprous bromide, cuprous oxide, cuprous sulfide, silver oxide, silver bromide, and silver sulfide. The gas sensor according to any one of appendices 1 to 5, characterized by:

(Appendix 7)
The first electrode includes a first detector-side portion connected to one end of the first detector, and a second detector-side portion connected to one end of the second detector,
The second electrode includes a first detector-side portion connected to the other end of the first detector, and a second detector-side portion connected to the other end of the second detector,
A first changeover switch for switching connection / disconnection between the first detector-side portion and the second detector-side portion of the first electrode;
The supplementary switch according to any one of appendices 1 to 6, further comprising a second changeover switch that switches connection / disconnection between the first detector-side portion and the second detector-side portion of the second electrode. Gas sensor.

(Appendix 8)
The first detector body side portion and the second detector body side portion of the first electrode are disconnected by the first changeover switch, and the first detector body side portion of the second electrode is disconnected by the second changeover switch. With the second detector body side portion disconnected, the first detector and the second detector body have a forward direction so that the first electrode is on the low potential side and the second electrode is on the high potential side. The potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a voltage of The potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying reverse voltages so that the two electrodes are on the low potential side, and the first detector and the second detector Calibrate the measured value using the overall resistance value of Characterized in that it comprises a calibration unit, a gas sensor according to Appendix 7.

(Appendix 9)
The gas sensor according to any one of appendices 1 to 8,
An information processing system comprising: a computer that processes data obtained by the gas sensor.
(Appendix 10)
The gas sensor according to any one of appendices 1 to 6,
A computer for processing data obtained by the gas sensor,
The gas sensor includes a first detector body side portion in which the first electrode is connected to one end portion of the first detector body, and a second detector body side portion in which the first electrode is connected to one end portion of the second detector body. And a second detector body side portion connected to the other end portion of the second detector body, and the second electrode is connected to the other end portion of the first detector body. A first changeover switch for switching connection / disconnection between the first detector-side portion and the second detector-side portion of the first electrode, the first detector-side portion of the second electrode, and the first electrode 2 with a second changeover switch for switching connection / disconnection with the sensing object side part,
The computer disconnects the first detector-side portion and the second detector-side portion of the first electrode by the first switch, and the first electrode of the second electrode by the second switch. The first electrode is on the low potential side and the second electrode is on the high potential side of the first and second detection bodies in a state where the detection body side portion and the second detection body side portion are disconnected. Thus, the potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a forward voltage, and the first electrode has a high potential to the first detector and the second detector. Side, the potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a reverse voltage so that the second electrode is on the low potential side, the first detector and the Using the overall resistance value of the second detector The information processing system characterized in that it comprises a calibration unit for calibrating the measurement.

DESCRIPTION OF SYMBOLS 1 Gas sensor device 2 1st detection body 3 2nd detection body 4 1st electrode 4A 1st detection body side part 4B 2nd detection body side part 5 2nd electrode 5A 1st detection body side part 5B 2nd detection body side part 6 1st intermediate electrode 7 Second intermediate electrode 8 First covering portion 9 Second covering portion 10 Power supply 11 Potentiometer 12 First changeover switch 13 Second changeover switch 14 Calibration portion 15 Gas sensor 16 Computer 17 Network 18 Computer 19 Information processing system 20 CPU
21 computer

Claims (9)

A first detector;
A second detector;
A first electrode connected to one end of the first detector and the second detector;
A second electrode connected to the other end of the first detector and the second detector;
A first intermediate electrode provided in the middle of the first detector;
A second intermediate electrode provided in the middle of the second detector;
A first covering portion that covers a portion from the first electrode to the first intermediate electrode of the first detector;
A second covering portion covering a portion from the second electrode to the second intermediate electrode of the second detector;
The first intermediate electrode and the second intermediate electrode are arranged along the length direction of the first detector and the second detector extending between the first electrode and the second electrode. A gas sensor characterized by being displaced.   And a potentiometer that measures a potential of the first intermediate electrode, a potential of the second intermediate electrode, and a potential difference between the potential of the first intermediate electrode and the potential of the second intermediate electrode. The gas sensor according to claim 1.   The gas sensor according to claim 1, further comprising a constant voltage power source that supplies a constant voltage between the first electrode and the second electrode. The distance between the first electrode and the first intermediate electrode is x, and the length of the region where the first intermediate electrode is provided is subtracted from the distance between the first electrode and the second electrode. 9.5 / (0.6+ (x / l)) − 5.8 <y / l where l is the distance and y is the distance between the second electrode and the second intermediate electrode. The positions of the first intermediate electrode and the second intermediate electrode are set so as to satisfy the relationship of <0.98-0.95 (x / l) ^2. The gas sensor according to any one of the above.   The gas sensor according to claim 1, wherein the first detector and the second detector are copper or silver compounds. The first electrode includes a first detector-side portion connected to one end of the first detector, and a second detector-side portion connected to one end of the second detector,
The second electrode includes a first detector-side portion connected to the other end of the first detector, and a second detector-side portion connected to the other end of the second detector,
A first changeover switch for switching connection / disconnection between the first detector-side portion and the second detector-side portion of the first electrode;
6. The switch according to claim 1, further comprising a second changeover switch that switches connection / disconnection between the first detector-side portion and the second detector-side portion of the second electrode. The gas sensor described.   The first detector body side portion and the second detector body side portion of the first electrode are disconnected by the first changeover switch, and the first detector body side portion of the second electrode is disconnected by the second changeover switch. With the second detector body side portion disconnected, the first detector and the second detector body have a forward direction so that the first electrode is on the low potential side and the second electrode is on the high potential side. The potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a voltage of The potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying reverse voltages so that the two electrodes are on the low potential side, and the first detector and the second detector Calibrate the measured value using the overall resistance value of Characterized in that it comprises a calibration unit, a gas sensor according to claim 6. A gas sensor according to any one of claims 1 to 7,
An information processing system comprising: a computer that processes data obtained by the gas sensor. A gas sensor according to any one of claims 1 to 5,
A computer for processing data obtained by the gas sensor,
The gas sensor includes a first detector body side portion in which the first electrode is connected to one end portion of the first detector body, and a second detector body side portion in which the first electrode is connected to one end portion of the second detector body. And a second detector body side portion connected to the other end portion of the second detector body, and the second electrode is connected to the other end portion of the first detector body. A first changeover switch for switching connection / disconnection between the first detector-side portion and the second detector-side portion of the first electrode, the first detector-side portion of the second electrode, and the first electrode 2 with a second changeover switch for switching connection / disconnection with the sensing object side part,
The computer disconnects the first detector-side portion and the second detector-side portion of the first electrode by the first switch, and the first electrode of the second electrode by the second switch. The first electrode is on the low potential side and the second electrode is on the high potential side of the first and second detection bodies in a state where the detection body side portion and the second detection body side portion are disconnected. Thus, the potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a forward voltage, and the first electrode has a high potential to the first detector and the second detector. Side, the potential of the first intermediate electrode and the potential of the second intermediate electrode measured by applying a reverse voltage so that the second electrode is on the low potential side, the first detector and the Using the overall resistance value of the second detector The information processing system characterized in that it comprises a calibration unit for calibrating the measurement.

Images