JP5429818B2 - Gas analyzer - Google Patents

Description

  The present invention relates to a gas analyzer, and more particularly, to a gas analyzer having a function of notifying when the detection accuracy of a gas sensor has increased.

  Japan's population is declining and the birthrate is declining, and the proportion of elderly people over the age of 65 is rapidly increasing. Specifically, in 2013, approximately 1 in 4 people, approximately 25.2% of the total population, became elderly, and in 2035, approximately 1 in 3 people, approximately 33.7% of the total population. Are said to be elderly. The older the elderly, the greater the proportion of medical institutions that are used, so the medical burden is expected to increase in the future.

  In addition, the metabolic syndrome has become a problem for young people due to the fact that the living environment has been remarkably improved and the opportunity to move the body has decreased due to advances in IT technology. The population of young people suffering from is increasing year by year. In this way, opportunities for young people to use medical care are increasing.

  From the trend of such times, it is said that the burden of medical care will reach its limit in the last few years, and it is desired to reduce the medical burden as much as possible. Therefore, in recent years, preventive medical care that prevents an opportunity to use a medical institution has been attracting attention.

  By enhancing preventive medical care, it is possible to prevent suffering from illness, thereby reducing the population suffering from illness. If the population suffering from illness is reduced by preventive medical treatment, not only can the medical burden be reduced, but there is also an advantage that the medical burden can be reduced in the present age when the medical insurance system is shattered. .

  Therefore, in order to enhance preventive medicine, it is desirable to spread a system for obtaining health information for individuals to easily perform health management with familiar devices in each home. Examples of indices for obtaining health information include biological samples such as blood pressure, blood, urine, sweat, saliva, and exhaled breath. Such a biological sample contains a plurality of substances whose numerical values change due to disease or signs thereof, such as blood glucose level in blood.

  By measuring the content rate of substances contained in a biological sample individually, it is possible to accurately grasp one's own health condition by obtaining health information. By objectively grasping the health condition of the person in this way, the disease can be detected at an early stage, and the life can be reviewed in advance so as to avoid it before suffering from the disease.

  Among the biological samples listed above, in particular, exhaled breath includes a plurality of substances whose numerical values change due to diseases or signs thereof, can be sampled and measured quickly and easily, and the measurement target is a gas. It is one of the most suitable biological samples for daily health care because it can be measured non-invasively and has little physical damage.

  Because of such advantages, research to identify diseases based on components contained in exhaled breath has become active. Previous studies have revealed that, for example, the components of exhaled breath in lung cancer patients are partially different from those in healthy individuals.

  More specifically, it has been found that if exhaled air contains a large amount of nitric oxide and carbon monoxide, the possibility of suffering from a lung disease is high. That is, exhaled breath in patients with asthma and chronic obstructive pulmonary disease (COPD) is detected at high concentrations of nitric oxide and carbon monoxide.

  To give another example of the correlation between the components of exhaled breath and the disease, exhaled breath in patients with gastrointestinal diseases such as dyspepsia and duodenal ulcers tends to be detected at high hydrogen concentrations. The breath of patients such as lipid oxidation, asthma and bronchitis is highly correlated with oxidative stress and tends to be detected at high concentrations of ethane, pentane and the like. Thus, by measuring the concentration of each component contained in exhaled breath, it is possible to obtain disease information and provide health guidance.

  Among the above, acetone in breath is produced when fat (fatty acid) and protein (amino acid) are decomposed, and thus has been conventionally positioned as an indicator of the activity of sugar metabolism. When you are extremely hungry, such as when you are fasting, and when you have severe diabetes, it is known to contain a lot of acetone in your breath. Therefore, it is considered that the amount of decrease in body fat can be clarified by grasping the amount of acetone contained in exhaled breath.

  The detailed mechanism by which body fat becomes acetone and is excreted outside the body will be explained. First, ketone bodies such as acetoacetic acid, hydroxybutyric acid, and acetone are produced in the blood in the process of fat metabolism. Of the produced ketone bodies, acetoacetic acid and hydroxybutyric acid are reused in organs other than the liver, and acetone is discharged to the outside through the lungs as breath. By the way, fat metabolism is performed by using body fat stored in the body as energy when blood glucose is consumed due to dietary restrictions or exercise.

  In this way, acetone is produced in the process of burning body fat, and is also contained and discharged in the exhaled breath. Therefore, by measuring the concentration of acetone in the exhaled breath, the body fat burning status is directly known. be able to. As a method of detecting the concentration of acetone contained in exhaled breath, conventionally, the components are separated using gas chromatography and then detected by a detector such as thermal conductivity type, flame ionization, electron capture type, mass spectrometry, etc. How to do is known.

  Since such acetone is contained in a very small amount in the exhaled breath, the appearance of an analyzer that improves the detection accuracy of acetone is desired. Therefore, Patent Literature 1 and Patent Literature 2 disclose gas analyzers that improve the detection accuracy of acetone.

  For example, in Patent Document 1, when a plurality of types of gas components are introduced into a gas chromatograph, the concentration of the gas components for each component can be detected even when the retention times of the plurality of gas components are close. An apparatus is disclosed. By using such a gas analyzer, it is possible to distinguish a gas component having a retention time equivalent to that of acetone, thereby improving the detection accuracy of acetone.

  Patent Document 2 discloses a gas component measuring device having a gas detector that detects a gas component, and a temperature sensor that detects the temperature of the gas detector and its peripheral portion. Such a gas component measuring device measures the ambient temperature of the gas detector when the temperature sensor starts driving, calculates the time until the gas detector reaches the standby temperature based on the temperature of the gas detector, The result is displayed on the display unit.

  The gas component measuring device of Patent Document 2 can introduce a gas component into the gas detector based on the state in which the subject is displayed on the display unit. Therefore, when the gas detector reaches the standby temperature, the gas component is measured. Can be introduced.

JP-A-2005-071144 Japanese Patent Laid-Open No. 03-243852

  However, in the gas component measuring device disclosed in Patent Document 2, for example, when the temperature change around the gas sensor is severe, the time until the gas detector reaches the standby temperature becomes inaccurate. For this reason, there is a problem that the sample gas is introduced before the detection accuracy of the gas sensor is stable.

  The present invention has been made in view of the above-described situation, and an object of the present invention is to provide a gas analyzer that notifies a subject accurately when the detection accuracy of a gas sensor is increased. .

The gas analyzer of the present invention includes a gas sensor for detecting a gas component contained in a sample gas, an arithmetic processing unit for calculating a resistance ratio of the gas sensor, and a resistance ratio calculated by the arithmetic processing unit is 1−. And a notification means for notifying the subject that the sample gas should be introduced when the resistance ratio is 2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more.

  The notification means preferably notifies the subject by one or both of a visual method and an audio method.

  It is preferable that the apparatus further includes a gas introduction unit that alternately switches between a first state in which the sample gas is not introduced into the gas sensor and a second state in which the sample gas is introduced into the gas sensor.

  It is preferable to further include switching means for switching between the first state and the second state. The resistance ratio is preferably calculated based on the resistance value of the gas sensor at two different times after the gas sensor is driven. The time of two different points here is 10 seconds or more. The sample gas is preferably exhaled air containing acetone.

A gas analyzer according to the present invention includes a gas introduction unit including a gas introduction port for introducing a sample gas, a gas separation unit including a microcolumn for separating a component of the sample gas supplied from the gas introduction unit, A gas sensor for detecting a gas component separated by the gas separation unit, an arithmetic processing unit for calculating a resistance ratio of the gas sensor, and a resistance ratio calculated by the arithmetic processing unit is 1-2 × 10 ⁻³ And a notification means for notifying the subject that the sample gas should be introduced when the resistance ratio is 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more.

  Since the gas analyzer of the present invention has the above-described configuration, it can accurately notify the subject when the detection accuracy of the gas component of the gas sensor has increased.

It is a schematic diagram which shows a state with an example of the gas analyzer of this invention. (A) is a schematic diagram which shows a state with an example of the gas analyzer of this invention, (b) is a schematic diagram which shows another one state of the gas analyzer of this invention. (A) is a schematic diagram which shows the 1st state of the gas analyzer of Example 1, (b) is a schematic diagram which shows the 2nd state of the gas analyzer of Example 1. FIG. It is the graph which showed the time change of the resistance value of a gas sensor after turning on the power supply of a gas analyzer. It is the graph which showed the time change of the resistance ratio of a gas sensor after turning on the power supply of a gas analyzer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configurations shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In the drawings of the present application, the dimensional relationships such as length, width, and thickness are appropriately changed for clarity and simplification of the drawings and do not represent actual dimensional relationships.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing an example of a gas analyzer of the present embodiment. As shown in FIG. 1, the gas analyzer of the present embodiment includes a gas sensor 31 for detecting a gas component contained in the sample gas, and an arithmetic processing unit 40 for calculating a resistance ratio of the gas sensor 31. When the resistance ratio calculated by the arithmetic processing unit 40 is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio is continued for 10 seconds or more, the sample gas should be introduced into the subject. And a notification means 50 for notifying.

  In an example of a conventional gas analyzer, the time until the detection accuracy of the gas sensor is stabilized is calculated based on the temperature around the gas sensor when the gas sensor is driven, and the sample gas is introduced after the calculated time has elapsed. It was to do. For this reason, for example, when the temperature change around the gas sensor is severe, the sample gas may be introduced before the detection accuracy of the gas sensor is stable.

  The present embodiment can effectively eliminate the above-described conventional drawbacks, and the notification means 50 supplies the subject gas to the subject based on the resistance ratio of the gas sensor 31 and the duration of the resistance ratio. It is characterized by telling what should be introduced. As a result, the moment when the detection accuracy of the gas sensor 31 is increased can be grasped in real time, and the sample gas can be introduced when the detection accuracy of the sample gas of the gas sensor 31 is increased.

  Hereinafter, the operation of the gas analyzer of the present invention will be described in detail with reference to FIG. First, when the gas sensor 31 is turned on, the arithmetic processing unit 40 calculates the resistance ratio of the gas sensor at intervals of 1 second after 10 seconds. Then, initially, the resistance ratio of the gas sensor 31 is high, but the resistance ratio of the gas sensor 31 gradually decreases with time.

When the resistance ratio of the gas sensor 31 is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more, the information is sent from the arithmetic processing unit 40 to the notification means 50. Reportedly. Upon receiving information from the arithmetic processing unit 40, the notification means 50 notifies the subject that the sample gas may be introduced. In accordance with this notification, the subject introduces the sample gas into the gas sensor 31. By detecting the sample gas by such a mechanism, the sample gas can be introduced when the detection accuracy of the gas sensor 31 is increased, and the sample gas can be detected with high accuracy. Below, each part which comprises the gas analyzer of this invention is demonstrated.

<Gas sensor>
In the present embodiment, the gas sensor 31 is provided for detecting the gas component of the specimen gas. As such a gas sensor 31, a semiconductor sensor, an electrochemical gas sensor, a flame ionization detector (FID: Flame Ionization Detector), an infrared sensor, a gas chromatography, or the like can be used. Among the above gas sensors, it is preferable to use a non-selective semiconductor sensor composed of SnO ₂ , ZnO or the like.

<Operation processing unit>
In the present embodiment, the arithmetic processing unit 40 has a function of calculating the resistance ratio of the gas sensor 31, the resistance ratio is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less, and the resistance ratio is 10 It has a function of transmitting information to the notification means 50 when it continues for more than a second. As such an arithmetic processing unit 40, for example, a computer (digital multimeter only receives signals) can be used. Here, the resistance ratio is preferably 1-1 × 10 ⁻³ or more and 1 + 1 × 10 ⁻³ or less, more preferably 1-2 × 10 ⁻⁴ or more and 1 + 2 × 10 ⁻⁴ or less. Such resistance ratio is preferably continued for 12 seconds or more, more preferably 15 seconds or more. Thereby, the time when the gas sensor 31 is stabilized can be more accurately transmitted to the notification means.

Even if the resistance ratio is less than 1-2 × 10 ⁻³ , exceeds 1 + 2 × 10 ⁻³ , or the duration of the resistance ratio is less than 10 seconds, the resistance value of the gas sensor 31 is sufficient. In such a case, even if the sample gas is introduced at this time, the detection accuracy of the gas sensor 31 is not sufficient.

Here, the resistance ratio in the present invention employs a value calculated from a resistance value at a certain time after the gas sensor is turned on and a resistance value after 10 seconds from that time. That is, for example, if the resistance value of the gas sensor for a certain time is Ω ₁ and the resistance value of the gas sensor after 10 seconds is Ω ₂ , the resistance ratio of the gas sensor is calculated as Ω ₂ / Ω ₁ . In a normal case, the resistance value of the gas sensor is continuously calculated, and thus the resistance ratio of the gas sensor is also continuously calculated from 11 seconds after the measurement of the resistance value is started. Such a resistance ratio may be calculated as long as the time at two different points is calculated from 10 seconds to 30 seconds.

  Here, it is considered that the gas sensor gradually approaches a certain resistance value when a sufficient time elapses after the power is turned on. For this reason, the resistance ratio of the semiconductor sensor is theoretically 1 when a sufficient time has elapsed since the gas analyzer was turned on. It is ideal to introduce the sample gas into the semiconductor sensor when the resistance ratio of the semiconductor sensor becomes 1, but this requires a considerable time until measurement is possible, which is practical. I can't say that.

  The arithmetic processing unit 40 preferably receives a change in the voltage value of the constant resistance of the gas sensor 31 as a signal change when the gas sensor 31 detects a gas component. The arithmetic processing unit 40 preferably has a function of accumulating signal data detected by the gas sensor 31 and converting the signal data into a chromatogram.

<Notification means>
In the present embodiment, the notification means 50 is provided for notifying the subject of information received from the arithmetic processing unit 40. Such a notification means 50 preferably notifies the subject of information of the arithmetic processing unit 40 by one or both of a visual method and an auditory method. By informing the subject of the timing of introducing the sample gas in this way, the subject can introduce the sample gas into the gas sensor 31 when the detection accuracy of the gas sensor 31 is increased, thereby increasing the detection accuracy of the sample gas. be able to.

  Here, as the visual method, for example, a light emitting signal such as a lighting signal can be used. In addition, as the above-mentioned auditory method, a method that emits a sound such as a buzzer can be used. Needless to say, the visual method and the auditory method may be combined.

  The means for notifying the subject by the notification means 50 is not limited to the visual method or the auditory method. For example, when the detection accuracy of the gas sensor 31 increases for the subject due to the vibration of the gas analyzer itself. It may be something that conveys.

<Sample gas>
The sample gas that is separated using the gas analyzer of the present embodiment preferably contains acetone. When the resistance ratio of the gas sensor 31 is not stable, it is difficult to efficiently detect acetone contained in a trace amount in the sample gas, and even if it can be detected, the accuracy is not sufficient. . The gas analyzer according to the present embodiment can eliminate such a problem, and can accurately detect the concentration of acetone in the sample gas.

(Embodiment 2)
FIG. 2A is a schematic diagram showing a state of an example of the gas analyzer of the present embodiment, and FIG. 2B shows another state of the gas analyzer of FIG. It is a schematic diagram. As shown in FIGS. 2A and 2B, the gas analyzer of the present embodiment is provided with a gas introduction unit 10 and a gas separation unit 20 with respect to the gas analyzer of the first embodiment. Other than that, the second embodiment is the same as the first embodiment. In the following, the description of the same parts as those in Embodiment 1 is omitted.

  As shown in FIG. 2A, the gas analyzer of the present embodiment includes a gas introduction unit 10 having a gas introduction port 11 for introducing a sample gas, and a sample supplied from the gas introduction unit 10. A gas separation unit 20 having a microcolumn 21 for separating components of gas and a gas detection unit 30 for detecting a gas component separated by the gas separation unit 20 are provided. A gas storage unit 19 for holding gas, a first connecting means 12 for introducing a sample gas from the gas inlet 11 to the gas storage unit 19, and a sample gas from the gas storage unit 19 to the gas separation unit 20 Second connection means 13 for supplying and third connection means 14 for discharging a part of the sample gas introduced from the gas introduction port 11 from the gas storage part 19 to the gas discharge port are provided.

  In the gas analyzer according to the present embodiment, the gas introduction unit 10 has a first state in which the sample gas is not introduced into the gas sensor 31 (corresponding to FIG. 2A), and a second state in which the sample gas is introduced into the gas sensor. (Corresponding to FIG. 2B) can be switched alternately. Thus, the sample gas can be introduced into the gas sensor 31 by switching between the first state and the second state. Here, in the first state, the gas storage unit 19 is connected to the first connecting means 12 and the third connecting means 14. On the other hand, in the second state, the gas storage unit 19 is connected to the second connection means 13.

<Switching means>
In the present embodiment, the switching unit 18 is configured so that the gas storage unit 19 is in the first state (FIG. 2A) in which the gas storage unit 19 is connected to the first connection unit 12 and the third connection unit 14. Is provided to switch to the second state (FIG. 2B) connected to the second connecting means 13. By providing the switching means 18, unnecessary samples of the sample gas are discharged from the gas outlet through the third connection means 14, and necessary samples of the sample gas are discharged to the gas separation unit through the second connection means 13. 20 is introduced.

  In the gas analyzer of the present embodiment, the amount and timing of introducing the sample gas into the gas separation unit 20 can be controlled by one switching means 18. This greatly simplifies the structure of the gas analyzer and contributes to its miniaturization.

  In the second state, when the sample gas is exhausted in the gas storage unit 19 or when the sample gas is sufficiently supplied to the gas separation unit 20, the switching unit 18 switches from the second state to the first state. When the second state is switched to the first state, the sample gas is again introduced from the first connecting means 12 into the gas storage unit 19. Thus, by alternately switching between the first state and the second state, it is possible to introduce the sample gas having an appropriate flow rate into the gas separation unit 20 at an appropriate timing.

  In the second state shown in FIG. 2B, the gas storage unit 19 is not connected to the first connecting means 12 and the third connecting means 14. For this reason, the sample gas introduced into the first connection means 12 in the second state is discharged to the outside through the third connection means 14 from the gas discharge port. Therefore, the notification means 50 connects the gas storage unit 19 and the second connection means 13 when the specific resistance of the gas sensor does not reach a desired value for the subject (that is, when the detection accuracy of the gas sensor 31 has not yet increased). By adopting the second state, the sample gas can be discharged to the outside without introducing the sample gas into the gas storage unit 19.

  Here, the switching from the first state to the second state is preferably performed after the notification means 50 notifies the subject that the sample gas should be introduced. Even if the notification means 50 notifies the subject that the sample gas should be introduced, switching to the second state is not preferable because the gas sensor 31 cannot accurately detect the gas component.

<Operation of gas analyzer>
When the power supply of the gas analyzer of the present embodiment is turned on, the arithmetic processing unit 40 calculates the resistance ratio of the gas sensor 31 at intervals of 1 second after 10 seconds. Then, the resistance ratio of the gas sensor 31 gradually decreases as time elapses after the power is turned on. Then, when the resistance ratio of the gas sensor 31 is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more, the information is transmitted from the arithmetic processing unit 40 to the notification means 50. It is done. Upon receiving information from the arithmetic processing unit 40, the notification means 50 notifies the subject that the sample gas may be introduced. In accordance with this notification, the subject switches the gas introduction unit 10 from the first state to the second state, and introduces the sample gas from the gas storage unit 19 through the gas separation unit 20 to the gas sensor 31.

  In the state shown in FIG. 2A (first state), the sample gas is supplied from the gas introduction port 11 to the gas storage unit 19 through the first connection unit 12, and from the gas storage unit 19 to the third connection unit. 14 through the gas outlet. Here, the flow velocity of the specimen gas flowing through the first connecting means 12 and the third connecting means 14 is controlled by the airflow generating means 25.

  On the other hand, as shown in FIG. 2A, in the first state, the second connection means 13 for supplying the sample gas to the gas separation unit 20 is not connected to the gas storage unit 19, It is connected to supply means 17 for supplying carrier gas. For this reason, the carrier gas supplied from the supply means 17 is supplied to the microcolumn 21 of the gas separation unit 20 through the second connection means 13.

  Next, by operating the switching unit 18, the connection destination of the gas storage unit 19 is changed from the state where the first connection unit 12 and the third connection unit 14 are connected (first state) to the second state. Switch to the state (second state) in which the connection means 13 is connected. By switching from the first state to the second state in this way, the sample gas in the gas storage unit 19 introduced from the first connection unit 12 is connected to the second connection together with the carrier gas supplied from the supply unit 17. The gas is supplied to the microcolumn 21 of the gas separation unit 20 through the means 13.

  The specimen gas supplied to the gas separation unit 20 is repeatedly adsorbed and desorbed with the stationary phase on the wall surface of the internal flow path 22 of the microcolumn 21, but the ease of adsorption and desorption differs for each component of the specimen gas. Therefore, the component of the sample gas is separated such that the component that is easily adsorbed to the stationary phase has a slower moving speed, and the component that is less easily adsorbed to the stationary phase has a higher moving speed.

  Here, the wall surface of the microcolumn 21 is modified with a stationary phase for separating water among the components of the sample gas. Conventionally, in detecting each component contained in the sample gas, moisture in the sample gas has been the most powerful component that hinders detection of gas components such as acetone. However, by modifying the stationary phase for separating water into the internal flow path 22 of the microcolumn 21 in this way, it is possible to efficiently separate the water contained in the sample gas. Details of the material constituting the stationary phase will be described later.

  Each gas component of the sample gas separated as described above is introduced into the gas detection unit 30 and is detected by the gas sensor 31 of the gas detection unit 30. The time from when the sample gas is introduced into the gas introduction unit 10 until the gas sensor 31 senses the gas component is referred to as a holding time, and this holding time shows a specific value depending on the component of the sample gas. Based on this holding time, the gas component is identified, and the gas component contained in the sample gas is detected.

In the present invention, the gas sensor 31 introduces the sample gas into the gas sensor 31 after the resistance value of 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less continues for 10 seconds or more. Therefore, the detection accuracy of the gas sensor is sufficiently stable. Therefore, the gas component can be accurately detected. Below, each part which comprises the gas analyzer of this Embodiment is demonstrated.

<Gas introduction part>
In the present embodiment, the gas introduction unit 10 is provided to supply a part of the specimen gas to the gas separation unit 20. Such a gas introduction unit 10 is not limited to the structure shown in FIG. 1, and any gas can be used as long as the flow rate and timing of the sample gas supplied to the gas separation unit 20 can be adjusted. It may be of a structure.

  Since the gas introduction unit 10 has the above-described structure, only the sample gas necessary for detection can be supplied to the gas separation unit 20 while discharging the sample gas unnecessary for detection to the outside. The operation of the gas introduction unit 10 of the present embodiment will be described below with reference to FIGS. 2 (a) and 2 (b).

  The gas introduction unit 10 is introduced from the gas introduction unit 11 for holding the sample gas, the first connection means 12 for introducing the sample gas from the gas introduction port 11 to the gas accommodation unit 19, and the gas introduction port 11. And third connecting means 14 for discharging a part of the sample gas from the gas storage part 19 to the gas discharge port. In the first state shown in FIG. 2A, the gas storage unit 19 is connected to the first connecting means 12 and the third connecting means 14.

  On the other hand, the gas introduction unit 10 includes a second connection unit 13 as a connection unit different from the first connection unit 12 and the third connection unit 14. Here, the second connecting means 13 is provided to supply the sample gas from the gas storage unit 19 to the gas separation unit 20. However, the second connecting means 13 fulfills the function of supplying the sample gas from the gas storage unit 19 to the gas separation unit 20 in the second state shown in FIG. That is, in the first state shown in FIG. 2A, the second connecting means 13 is connected to the microcolumn 21 of the gas separation unit 20 without being connected to the gas storage unit 19. The specimen gas is not supplied to the separation unit 20.

  Therefore, in the first state, the sample gas is not supplied to the gas separation unit 20, and the sample gas introduced from the first connection means 12 passes through the gas storage unit 19 and a part of the sample gas is gas. While being held in the storage portion 19, the remaining portion is discharged from the gas discharge port through the third connecting means 14.

  As in the gas analyzer of the present embodiment, it is preferable to have the fourth connecting means 15 for connecting the gas storage part 19 and the supply means 17. Thus, by connecting the supply means 17 and the gas storage portion 19 using the fourth connection means 15, the carrier gas can be efficiently supplied to the gas storage portion 19. In this case, the second state is a state in which the gas storage unit 19 is connected to the second connecting means 13 and the fourth connecting means 15.

<Supply means>
Like the gas analyzer of the present embodiment, it is preferable to have a supply means 17 for supplying the carrier gas to the gas storage unit 19 in the second state. By providing such a supply means 17, the sample gas held in the gas storage part 19 can be supplied to the gas separation part 20 through the second connection means 13 together with the carrier gas.

  Such a supply means 17 may be built in the gas introduction part 10 or connected to the gas storage part 19 as an apparatus different from the gas analyzer as shown in FIG. It may be a thing. Examples of the supply means 17 include a compressor, a gas cylinder, and a pump. As the carrier gas, for example, an inert gas such as helium or air is preferably used.

<Control unit>
The switching means 18 preferably has a control unit (not shown) that automatically controls the timing of switching from the first state to the second state or from the second state to the first state. By including the control unit, it is possible to automatically control the timing at which the switching unit 18 switches from the first state to the second state or from the second state to the first state. By operating the switching means 18 in this way, the timing for supplying the sample gas from the gas introduction unit 10 to the gas separation unit 20 can be controlled.

  The control unit preferably switches the switching unit 18 alternately at a constant time interval between the first state and the second state. Here, “each fixed time interval” means that the time for holding the first state and the time for holding the second state may be different. That is, for example, the switching unit 18 performs a series of operations of switching from the first state to the second state after holding the first state for 3 minutes, and further switching from the second state to the first state after holding the second state for 2 seconds. You may set a control part to repeat.

  By operating the switching means 18 at a constant time interval in this way, the sample gas can be detected at a constant time interval, and the time change of the component of the sample gas can be grasped. As an example effective for detecting the sample gas at a constant time interval, for example, a case where the time change of the acetone content in the sample gas is grasped during an exercise such as running or walking can be cited. That is, for example, in a 20-minute walk, the sample gas is detected a total of 6 times every 3 minutes from the start of walking, and the acetone concentration in each sample gas is measured, so that the concentration change of acetone can be grasped. Therefore, it is possible to grasp the time change of the burning efficiency of body fat.

  In this case, the switching means 18 repeats a series of operations of switching from the first state to the second state 3 minutes after starting walking, holding the second state for 2 seconds, and switching from the second state to the first state. It is preferable to set the control unit as described above. Such setting of the control unit can be performed by computer programming, for example.

  The gas introduction unit 10 preferably includes a detection sensor (not shown) for detecting the analyte gas in any of the first connection unit 12, the gas storage unit 19, or the third connection unit 14. And it is preferable to set a control part so that the switching means 18 may switch from a 1st state to a 2nd state based on the information which the said sensor detected. As described above, by providing the detection sensor in any of the first connection unit 12, the gas storage unit 19, and the third connection unit 14, the sample gas is introduced into the gas introduction port 11, and then the first state is started. The time until switching to the second state can be controlled.

  Here, the timing of switching from the first state to the second state will be described by taking as an example the operation of the switching means when the third connecting means 14 is provided with a sensing sensor and the sample gas is introduced. When the sample gas is introduced from the gas introduction port 11, the sample gas is introduced in the order of the first connection means 12, the gas storage unit 19, and the third connection means 14. When the sample gas passes through the third connecting means 14, the sensing sensor transmits the signal to the control unit, and after the sample gas is introduced into the third connecting means 14, for example, five seconds later, the first state changes to the second state. The control unit can be set such as switching to

  By setting the control unit in this way, for example, the first 150 ml of the sample gas out of the 500 ml of the sample gas discharged by one breath of an adult is discharged to the outside, and only the remaining 350 ml of the sample gas is discharged. The switching means can be operated so as to be supplied to the gas detection unit 30.

<Gas storage unit>
It is preferable that the gas accommodating part 19 can change the volume. Thereby, the flow rate of the specimen gas supplied to the gas separation unit 20 can be controlled. That is, for example, when the volume of the gas storage unit 19 is small, the amount of sample gas held in the gas storage unit 19 decreases, and the gas is supplied to the gas separation unit 20 by switching from the first state to the second state once. The flow rate of the specimen gas can be reduced.

The volume of the gas storage unit 19 is preferably 10 mm ³ or more and 100 mm ³ or less. If it is less than 10 mm ³ , the detection accuracy tends to decrease due to insufficient flow rate of the sample gas supplied to the gas separation unit 20, and if it exceeds 100 mm ³ , an excessive amount of sample gas will be present in the gas separation unit 20. And it becomes difficult to completely separate the components, and it is difficult for the gas sensor 31 to perform accurate detection.

<Pressure control means>
The gas introduction unit 10 preferably includes pressure adjusting means (not shown) for adjusting the pressure of the carrier gas supplied by the supply means 17. The flow rate of the sample gas (including the carrier gas) supplied to the gas separation unit 20 can be controlled by adjusting the pressure for introducing the carrier gas using the pressure adjusting means.

  The flow rate of the specimen gas controlled by such pressure adjusting means is not particularly limited and may be any speed, but is preferably 10 cm / sec or more and 100 cm / sec or less. If the flow rate of the sample gas is less than 10 cm / sec, it takes a long time to detect the gas, which is not preferable in terms of the specifications of the apparatus. If the flow rate of the sample gas exceeds 100 cm / sec, the flow rate is too fast, and it tends to be difficult to separate the component of the sample gas in the subsequent gas separation unit. As such a pressure adjusting means, for example, a valve, a regulator or the like can be used.

<Airflow generation means>
The gas introduction unit 10 is preferably provided with an airflow generation unit 25 that controls the flow rate of the sample gas flowing through the first connection unit 12. By providing the airflow generation means 25 in this way, the flow rate of the specimen gas flowing through the first connection means 12, the gas storage unit 19, and the third connection means 14 can be set to a desired speed, and the flow thereof Can prevent backflow. The flow rate of the sample gas controlled by the airflow generation means 25 is not particularly limited and may be any speed, but is preferably 1 mL / sec or more and 10 mL / sec or less.

<Gas separation unit>
In the present embodiment, the gas separation unit 20 is provided for component separation of various gas components contained in the sample gas introduced from the gas introduction unit 10. Specifically, the gas separation unit 20 includes The component of the sample gas can be separated from the microcolumn 21 provided.

  Here, the “microcolumn” means a chip-like chromatography column having a fine flow path having a width and depth of micro order. The external shape of such a microcolumn is not particularly limited. For example, using a substrate such as a Si wafer, the external shape is several mm to several tens cm in length and width, and the thickness is about several mm to several cm. be able to.

  The “component separation” of the detection gas means not only the case where all components constituting the sample gas are separated for each component, but also any one of the components constituting the sample gas, The case of separation from one component is also included. That is, when the sample gas includes three or more components, the component separation of the sample gas is achieved as long as at least one of the three or more components is separated from the other two or more components. It is included in the scope of the invention.

  The gas separation unit 20 may be a packed column packed with a carrier coated with a stationary phase, a capillary column with an inner wall coated with a stationary phase, or the like as a chromatography column other than a microcolumn. In order to control the temperature, it is necessary to provide a large thermostatic bath, which may undesirably increase the size of the gas analyzer itself, which is contrary to the intended purpose.

  Further, the width and depth (height) of the internal flow path of the microcolumn can be set to about 100 to 300 μm, for example. The width and depth of the internal flow path of the microcolumn are preferably determined in consideration of the type of the target component, the flow rate of the sample gas introduced into the microcolumn, and the like.

  The length of the internal flow path 22 is preferably 3 m or more and 30 m or less, more preferably 5 m or more and 25 m or less, and still more preferably 10 m or more and 20 m or less. If the length of the internal flow path 22 is less than 3 m, the sample gas cannot be sufficiently separated, and if the length of the internal flow path 22 exceeds 30 m, the measurement takes a long time. Therefore, it is not preferable.

  In the present embodiment, the stationary phase of the microcolumn 21 is modified on the wall surface of the internal flow path 22, and the stationary phase is preferably made of a polar material having a relative dielectric constant of 10 or more at 30 ° C. . Such a polar material having a relative dielectric constant of 10 or more is highly polar, so that the flow rate of a polar substance such as water is remarkably slowed down, so that water in the components contained in the sample gas is efficiently used. Components can be separated.

  Examples of such a polar material having a relative dielectric constant of 10 or more include polyethylene glycol having an average molecular weight of 1000 or less, ethylene glycol, propylene glycol, polypropylene glycol and the like. In addition, the value computed using the dielectric constant measuring apparatus shall be employ | adopted for the dielectric constant of the material which comprises a stationary phase.

  It is considered that the stronger the polarity of the stationary phase, the more the difference in polarity of each component of the sample gas causes a difference in the moving speed of the sample gas flowing through the microcolumn, and the easier it is to separate the sample gas. The strength of the polarity of the stationary phase is determined by the relative dielectric constant of the material, so that the material constituting the stationary phase preferably has a relative dielectric constant of 11 or more, more preferably It has a relative dielectric constant of 13 or more. If the relative dielectric constant of the material constituting the stationary phase is less than 10, it is not preferable because water in the sample gas cannot be separated.

  Here, it is more preferable to use polyethylene glycol (hereinafter also referred to as “PEG”) having an average molecular weight of 200 to 1000 as an effective stationary phase material for separating the water in the sample gas. preferable. As the average molecular weight of PEG increases, the viscosity increases and the polarity tends to decrease. As the average molecular weight decreases, the viscosity decreases and the polarity tends to increase. For this reason, from the viewpoint of the balance between the viscosity and the polarity of PEG, it is more preferable to use PEG (PEG 600) having a relative dielectric constant of 12.7 at 25 ° C. and an average molecular weight of about 600.

  When the average molecular weight of polyethylene glycol is less than 200, it is difficult to be held on the wall surface of the internal flow path 22 of the microcolumn 21 due to its low viscosity, and when the average molecular weight of polyethylene glycol exceeds 1000, it does not have sufficient polarity. For this reason, the separation performance of the sample gas tends to be reduced. The microcolumn 21 may include a temperature control unit. By providing the temperature control means, the temperature of the microcolumn 21 can be kept constant, so that component separation can be performed more accurately.

  Further, from the viewpoint of improving the performance of separating the sample gas components, the thickness of the stationary phase modified on the wall surface of the internal flow path of the microcolumn is preferably 1 μm or more and 2 μm or less.

  Here, the thickness of the stationary phase is calculated by directly measuring the cross-section of the microcolumn with the stationary phase modified on the wall surface of the internal channel based on the image observed with a laser microscope. To do.

<Preparation of microcolumn>
A method for manufacturing a microcolumn in this embodiment will be described with a specific example. First, continuous grooves are formed on the surface of a substrate such as a Si wafer by performing fine processing such as etching or blasting using a photolithography technique.

  Next, the substrate on which the continuous grooves are formed and the glass plate are hermetically bonded by a technique such as anodic bonding so that the groove forming surface side of the substrate faces the glass plate. Next, unmodified capillary glass is attached to one end of the formed internal channel, and the solution in which the stationary phase is dissolved is filled in the internal channel of the microcolumn. Thereafter, the stationary phase is modified on the inner wall of the internal flow path of the microcolumn by removing the solvent.

<Gas detector>
In the present embodiment, the gas detection unit 30 is a part for sequentially detecting the gas components separated by the gas separation unit 20, and a gas sensor is preferably used. In the present embodiment, the gas detection unit 30 includes a gas sensor 31 for detecting a chemical substance. As the gas sensor 31, the same one as that shown in the first embodiment can be used.

The gas detection unit 30 is a part for sequentially detecting the gas components separated by the gas separation unit 20, and includes a gas sensor 31 for detecting the gas components. As the gas sensor 31, a semiconductor sensor, an electrochemical gas sensor, a flame ionization detector (FID), an infrared sensor, a GCM, or the like can be used. In this embodiment, a non-selective semiconductor sensor composed of SnO ₂ , ZnO or the like is used.

  In the present embodiment, the gas sensor 31 is preferably installed in the vicinity of the outlet of the gas component separated by the gas separation unit 20. Thus, by installing the gas sensor 31 in the vicinity of the gas component outlet, the detection sensitivity of the target component in the sample gas can be increased. The internal flow path of the microcolumn of the gas separation unit 20 and the gas detection unit 30 are connected by a capillary glass tube.

  As described above, the gas separation unit 20 and the gas detection unit 30 are connected using a capillary glass tube. Since the tube diameter of the capillary glass tube is small, the gas component outlet of the capillary glass tube and the gas sensor 31 are connected. Is not preferable because the gas sensor 31 tends to hardly detect the sample gas.

  The gas sensor 31 is preferably connected to a signal receiving mechanism (not shown) such as a digital multimeter via a conducting wire or the like. Such a signal receiving mechanism needs to receive a change in the voltage value of the constant resistance of the gas sensor 31 as a signal change when the gas sensor 31 detects a gas component.

  Furthermore, the signal receiving mechanism is preferably connected to a computer. Here, the computer refers to a computer that accumulates signal data detected by the signal receiving mechanism, converts the signal data into a chromatogram, and displays the converted data. Note that the computer may have a function of switching means, and may also serve as a control unit that switches between the first state and the second state.

(Gas sampling part)
In the gas analyzer of the present embodiment, it is preferable to connect a gas sampling unit to the gas inlet 11 and the gas outlet 16. By connecting the gas sampling part, the sample gas can be efficiently introduced into the gas inlet 11 and a space for accommodating the sample gas can be provided.

  Moreover, such a gas collection unit also serves as a circulation path through which the sample gas circulates through the gas collection unit, the first connection unit 12, the gas storage unit 19, and the third connection unit 14.

  It is preferable that the introduction port of the gas sampling unit has a mouthpiece, a mask or the like that can directly introduce the sample gas by opening the mouth. Thus, by having a mouthpiece, a mask, etc., it is easy to introduce the sample gas into the gas sampling part.

  Although the case where the sample gas is introduced into the gas introduction unit 10 using the gas collection unit has been described, the method of introducing the sample gas into the gas introduction unit 10 is not limited to the case where the gas collection unit is used. Alternatively, the sample gas may be introduced into the gas introduction unit 10 by connecting a bag directly to the gas introduction port 11.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  FIG. 3 is a schematic diagram showing a state of an example of the gas analyzer of the present invention. In this example, the gas analyzer shown in FIG. 3 was manufactured by the following procedure. First, as the gas separation unit 120, a microcolumn 121 in which internal channels 122 having a width of 200 μm and a depth of 200 μm were formed in a meandering manner at intervals of 200 μm was manufactured. Hereinafter, a procedure for manufacturing the microcolumn 121 will be specifically described.

  First, a 6-inch silicon wafer was subjected to photolithography and then etched to form serpentine grooves having a width of 200 μm and a depth of 200 μm at intervals of 200 μm. The total length of the internal flow path 122 formed in this way was about 16 m. Then, a 6-inch glass plate was adhered to the side of the silicon substrate where the grooves were formed using anodic bonding. Then, an 8 cm square microcolumn was produced by dicing.

  Capillary glass having an outer diameter of 0.35 mm, an inner diameter of 0.25 mm, and an inner surface with an unmodified surface was attached to the inlet and outlet of the internal flow path 122 thus obtained. .

  On the other hand, polyethylene glycol (PEG 600: manufactured by GL Sciences Inc.) having an average molecular weight of 600 and a relative dielectric constant of 13.74 at 30 ° C. was dissolved in acetone to prepare a 0.5% acetone solution. The 0.5% acetone solution was introduced from the introduction port of the microcolumn 121 of the gas separation unit 120, and the acetone solution was filled in the internal flow path 122.

  And the acetone in the internal flow path 122 was almost evaporated by hold | maintaining for 10 minutes, after heating up the gas separation part 120 to 80 degreeC using a hotplate. After substantially evaporating acetone in this way, a diaphragm type dry vacuum pump DA-15D (manufactured by ULVAC Kiko Co., Ltd.) having a solvent trap was connected to the inlet side of the internal flow path 122.

  By operating this vacuum pump for several tens of minutes to completely remove the solvent in the internal flow path 122, the gas separation unit 120 having a stationary phase made of PEG 600 on the wall surface of the internal flow path 122 of the microcolumn 121. Formed. When the cross section of the gas separation part 120 thus produced was observed with a laser microscope and the thickness of the stationary phase was measured, it was found that the thickness of the stationary phase was 1 μm.

  Next, a manual gas sampler for gas chromatography (manufactured by GL Sciences Inc.) was prepared as the gas introduction unit 110. Here, a manual gas sampler for gas chromatography (hereinafter also referred to as “gas sampler”) includes a first flow path 112 for introducing the sample gas and a second channel for supplying the sample gas to the gas separation unit 120. A flow path 113, a third flow path 114 for discharging a part of the sample gas from the gas discharge port, a fourth flow path 115 for introducing the carrier gas, and a gas storage section for holding the sample gas 119. Here, the inner diameters of the first flow path 112, the second flow path 113, the third flow path 114, and the fourth flow path 115 were all 0.8 mm.

  In such a gas sampler, the gas storage unit 119 is connected to the first flow path 112 and the third flow path 114, and the gas storage section 119 is connected to the second flow path 113 and the fourth flow path 115. The switching unit 118 for alternately switching between the second state and the second state is connected to a control unit (not shown) for controlling the switching timing.

  Further, the fourth flow path 115 is provided with a supply means 117, and the flow speed of the carrier gas supplied from the fourth flow path 115 to the gas storage unit 119 is controlled by the supply means 117. On the other hand, the third flow path 114 is provided with a detection sensor, and when the information when the sample gas passes through the detection sensor is transmitted to the control section, the control section operates the switching means 118 based on the information. Controlled.

  The first flow path 112 and the third flow path 114 of the gas sampler were connected to the gas sampling unit 142, respectively. A check valve 141 is provided at each of the outlet and inlet of the gas sampling section 142 to prevent the sample gas from flowing back. A small pump as an air flow generating means 125 was attached to the connection part between the third flow path 114 and the gas sampling part 142. This small pump circulated the sample gas through the first flow path 112, the gas storage part 119, the third flow path 114, and the gas sampling part 142.

  On the other hand, the second flow path 113 of the gas sampler and the internal flow path 122 of the microcolumn 121 were connected using a 1/16 × 0.25 reducing union. As a result, the carrier gas introduced from the fourth channel 115 of the gas sampler was introduced into the internal channel 122 of the microcolumn 121 through the second channel 113.

  Next, it connected by inserting the end of a capillary tube with respect to the micro column 121 of the gas separation part 120. FIG. On the other hand, the other end of the capillary tube was connected to the semiconductor sensor 131 of the gas detection unit 130 at a position of 1.5 mm.

In addition, an arithmetic processing unit 140 that can calculate the resistance value of the semiconductor sensor 131 is connected to the semiconductor sensor 131. The arithmetic processing unit 140 and the notification unit 150 are connected. The arithmetic processing unit 140 transmits the information to the notification unit 150 when the resistance ratio of the semiconductor sensor 131 becomes 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the time continues for 10 seconds or more. A thing was used. As the notification unit 150, a red lamp is used, and the notification unit 150 is set to light red when information from the arithmetic processing unit 140 is transmitted. The gas analyzer of Example 1 was produced as described above.

<Operation of gas analyzer>
The gas analyzer of Example 1 was turned on, and the time change of the resistance value of the semiconductor sensor 131 was calculated using the arithmetic processing unit 140. FIG. 4 is a graph showing the change over time of the resistance value of the semiconductor sensor after the gas analyzer is turned on. The vertical axis in FIG. 4 represents the resistance value of the semiconductor sensor, and the horizontal axis in FIG. 4 represents the time since the gas analyzer was turned on.

  As shown in FIG. 4, the resistance value of the semiconductor sensor 131 increases with time after the gas analyzer is turned on, but the resistance value gradually begins to settle. FIG. 4 shows the resistance value until 17 minutes after the gas analyzer was turned on, but after this time, the resistance value was about 65 kΩ.

  FIG. 5 is a graph showing the change over time in the resistance ratio of the semiconductor sensor after the gas analyzer is turned on. The vertical axis in FIG. 5 indicates the resistance ratio of the semiconductor sensor, and the horizontal axis in FIG. 5 indicates the time since the gas analyzer is turned on. Here, the time of two different points for calculating the resistance ratio was set to 10 seconds. That is, assuming that the time from when the gas analyzer is turned on is t seconds and the resistance value of the semiconductor sensor at t seconds is Ω (t), the resistance ratio of the semiconductor sensor is Ω (t + 10) in FIG. ) / Ω (t).

At this time, the resistance ratio of the gas sensor became 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less 15 minutes and 47 seconds after the gas analyzer was turned on, and the resistance ratio was maintained for 10 seconds. Is transmitted from the arithmetic processing unit 140 to the notification means 150, and the notification means 150 blinks red. When the subject confirmed that the notification unit 150 was blinking, the subject switched the state of the gas introduction unit 110 from the first state to the second state by the switching unit 118. Thus, the sample gas was introduced from the gas storage unit 119 into the gas separation unit 120, and the component analysis of each component contained in the sample gas was performed by the semiconductor sensor 131.

  By using the arithmetic processing unit 140 of the gas analyzer of Example 1 to determine the timing at which the subject introduces the sample gas based on the above-described determination criteria, the component of the sample gas is more accurate than the conventional gas analyzer. Analysis was done. This is considered to be due to the provision of a notification means that can accurately notify when the detection accuracy of the gas sensor is higher than before.

  The gas analyzer of the present invention that operates in this way can accurately notify the subject when the detection accuracy of the gas sensor is increased, thereby increasing the detection accuracy of the sample gas.

  Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, it is possible to provide a gas analyzer that is effective in promoting preventive medicine, is small, and is suitable for personal use.

  DESCRIPTION OF SYMBOLS 10,110 Gas introduction part, 11 Gas introduction port, 12 1st connection means, 13 2nd connection means, 14 3rd connection means, 15 4th connection means, 16 Gas discharge port, 17,117 Supply means , 18, 118 switching means, 19, 119 gas storage part, 20, 120 gas separation part, 21, 121 microcolumn, 22, 122 internal flow path, 25, 125 air flow generation means, 30, 130 gas detection part, 31 gas sensor , 40, 140 Arithmetic processing unit, 50, 150 Notification means, 110 Gas introduction unit, 112 First flow path, 113 Second flow path, 114 Third flow path, 115 Fourth flow path, 131 Semiconductor sensor, 141 Check Valve, 142 Gas sampling part.

Claims (7)

A gas sensor for detecting a gas component contained in the sample gas;
An arithmetic processing unit for calculating a resistance ratio of the gas sensor;
When the resistance ratio calculated by the arithmetic processing unit is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more, the subject is notified that the sample gas should be introduced. for example Bei and a notification means,
The resistance ratio is calculated based on resistance values of the gas sensor at two different times after the gas sensor is driven .   The gas analyzer according to claim 1, wherein the notification means notifies the subject by one or both of a visual method and an audio method.   3. The gas analyzer according to claim 1, further comprising a gas introduction unit that alternately switches between a first state in which the sample gas is not introduced into the gas sensor and a second state in which the sample gas is introduced into the gas sensor.   The gas analyzer according to claim 3, further comprising switching means for switching between the first state and the second state. The gas analyzer according to claim 1 , wherein the time of the two different points is 10 seconds or more. The sample gas is exhaled breath comprising acetone, gas analyzer according to any one of claims 1-5. A gas introduction unit having a gas introduction port for introducing the sample gas;
A gas separation unit comprising a microcolumn for separating components of the sample gas supplied from the gas introduction unit;
A gas sensor for detecting a gas component separated by the gas separation unit;
An arithmetic processing unit for calculating a resistance ratio of the gas sensor;
When the resistance ratio calculated by the arithmetic processing unit is 1-2 × 10 ⁻³ or more and 1 + 2 × 10 ⁻³ or less and the resistance ratio continues for 10 seconds or more, the subject is notified that the sample gas should be introduced. for example Bei and a notification means,
The resistance ratio is calculated based on resistance values of the gas sensor at two different times after the gas sensor is driven .

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