KR20200077639A - Apparatus for measuring gas concentration and Method for measuring gas concentration using the same - Google Patents

Abstract

The present invention relates to a gas concentration measurement apparatus. According to the present invention, the gas concentration measurement apparatus includes: an exhalation passage in which exhalation flows; a sample gas chamber connected to the exhalation passage and taking sample gas which is part of the exhalation flowing in the exhalation passage; a semiconductor type gas sensor placed in the sample gas chamber and including a sensing part generating an electric signal in accordance with the concentration of measurement target gas and a heater heating the sensing part; and a controller controlling the heater, and receiving the electric signal from the semiconductor type gas sensor to calculate the concentration of the measurement target gas. A gas concentration measurement method using the gas concentration measurement apparatus includes: a warm-up step (a) of heating the sensing part by applying power to the heater; a stabilization determination step (b) measuring a resistance value of the sensing part in a state in which measurement step heater power (Tm) has been applied to the heater; a step (c) of making the exhalation flow into the exhalation passage; a measurement standby step (d) of applying the measurement step heater power (Tm) to the heater; and a step (e) of calculating the concentration of the measurement target gas by receiving the electric signal from the semiconductor type gas sensor when the exhalation flows into the exhalation passage. If the sensing part is determined to be stable in the step (b), the step (e) proceeds after the step (b). Whereas, if the sensing part is determined to be unstable in the step (b), the steps (c, d) and (e) sequentially proceed after the step (b). Therefore, the gas concentration measurement apparatus is capable of accurately and quickly measuring the concentration of low-concentration measurement target gas.

Description

Gas concentration measuring device and gas concentration measuring method using the same{Apparatus for measuring gas concentration and Method for measuring gas concentration using the same}

The present invention relates to a gas concentration measuring apparatus, and more particularly, to a semiconductor-type gas concentration measuring apparatus for detecting the concentration of a gas to be measured, such as acetone and alcohol at a low concentration contained in the exhalation of a subject.

The energy used by the human body is mainly glucose, blood sugar, protein, and body fat. It is known that the human body primarily uses blood sugar as energy, followed by protein and finally fat. Therefore, normally, blood sugar is used as the main energy source, but there are special situations, such as diabetes, fasting starvation, energy consumption due to intense exercise, and dietary conditions such as restriction of carbohydrate intake. Body fat is used as an energy source.

When the human body uses body fat as an energy source, a ketone body is produced as a product of fat decomposition. This ketone body is a generic term for three substances including acetoacetic acid, β-hydroxybutyric acid and acetone produced by decarbonation of these substances. It is known that ketone bodies are produced in the liver of the human body, circulate through the blood, and are used as an energy source in the brain, and the rest are excreted as exhalation gas and urine through the lungs. If it is possible to detect a trace amount of ketone body in blood, it is possible to know how much body fat is being burned, so detection of ketone body in blood can be very useful for diet programs aimed at reducing body fat.

Urine and blood tests are the most common methods for determining the concentration of ketone bodies in the human body.

Urine test is a method of determining the concentration of ketone bodies in the human body through a change in color of a test strip according to the concentration of ketone bodies contained in urine, and has a merit of a relatively simple measurement method. However, the urine test is an inadequate means of knowing the current concentration because it is a means of telling the concentration of ketones in the body about 4 hours ago. In addition, it is not suitable for quantitative analysis because the test results vary greatly depending on the amount of water intake and the like.

The method by blood test can quantitatively measure the amount of ketones present in the blood relatively accurately, but there is a hassle of taking blood.

In addition to the above-described method for measuring the concentration of ketone bodies, a technique for measuring the amount of ketone bodies in blood by analyzing aerobic gas has been recently studied. Since the acetone contained in the exhalation gas is closely related to the amount of ketone body contained in the blood, the amount of the ketone body in the blood can be calculated by measuring the amount of acetone contained in the exhalation gas. The aerobic gas mainly contains acetone among ketone bodies.

For example, U.S. Patent No. 4,970,172 discloses a method for measuring the amount of acetone by reacting acetone contained in an exhalation gas with a matrix material comprising a nitroprusside salt and an amine. In addition, U.S. Patent No. 8,871,521 discloses an apparatus comprising a container with a powder that changes color when reacted with a ketone body (mainly acetone) contained in aerobic gas. However, this method has a problem that it is impossible to measure the amount of ketone contained in aerobic gas in real time.

As a method for improving this problem, US Patent Publication No. 2003-0208133 discloses a method of measuring metabolic rate and the amount of ketone body contained in aerobic gas, and estimating body fat decomposition amount using the measured metabolic rate and ketone body amount. have. However, these devices have a complicated structure and are difficult to carry.

In addition, Korean Patent Publication No. 2003-0009013 discloses a method of measuring the amount of ketone contained in the exhaled gas collected by the exhaled gas collecting unit using a semiconductor-type ketone gas sensor. In addition, U.S. Patent No. 9,456,749 discloses a portable electronic device that measures ketone concentration using a metal oxide sensor. However, the method using the semiconductor gas sensor has a problem that it is difficult to distinguish acetone from other components included in the exhalation gas due to poor selectivity and stability.

In addition, there is a problem that a warm-up of about 1 hour is required to completely stabilize the semiconductor gas sensor in order to detect a low concentration of 1 ppm or less. If the measurement is not sufficiently stabilized, there is a high possibility of malfunction due to the presence of acetone even if the acetone concentration is incorrectly measured as high or there is no acetone.

In the above, the description was made using acetone as an example, but the same problem may occur when detecting other low concentration gas such as alcohol other than acetone.

U.S. Patent No. 4,970,172 U.S. Patent No. 8,871,521 US Patent Publication No. 2003-0208133 Korean Patent Publication No. 2003-0009013 U.S. Patent No. 9,456,749 U.S. Patent No. 7,790,467 U.S. Patent No. 9,089,279

An object of the present invention is to improve the above-mentioned problems, and to provide a semiconductor-type gas concentration measuring device and a gas concentration measuring method capable of quickly and accurately measuring the concentration of a gas to be measured at a low concentration.

In order to achieve the above object, the present invention, the exhalation passage through which the exhalation flows, the sample gas chamber which is in communication with the exhalation passage and which is part of the exhalation passage through which the sample gas flows, and the inside of the sample gas chamber The semiconductor gas sensor is disposed and includes a sensing unit that generates an electrical signal according to the concentration of the gas to be measured and a heater that heats the sensing unit. A gas concentration measuring method using a gas concentration measuring device comprising a controller for calculating the gas concentration,

a) a warm-up step of applying the electric power to the heater to heat the sensing unit, and b) a stabilization determining step of measuring the resistance value of the sensing unit in a state in which the heater electric power Tm is applied to the heater, and c) A step in which exhalation is introduced into the exhalation passage, d) a measurement standby step in which heater power Tm is applied to the heater, and e) an electrical signal from the semiconductor gas sensor when exhalation is introduced into the exhalation passage. And calculating the concentration of the gas to be measured by receiving, and if it is determined in step b) that the detector is stable, step e) after step b) proceeds, and in step b), the detector If it is determined to be unstable, a method for measuring gas concentration in which steps c), d) and e) are sequentially performed after step b) is provided.

In addition, the step a) provides a gas concentration measurement method comprising a high temperature warm-up step of applying an accelerated warm-up power (Pw) 10 to 50% greater than the heater power Tm of the measurement step.

In addition, the step a) provides a gas concentration measurement method including a general warm-up step of applying a heater power Tm to the heater.

In addition, it provides a gas concentration measuring method further comprising the step of applying a high temperature warm-up power (Pw) to the heater immediately before the step d).

In addition, it provides a gas concentration measuring method further comprising the step of applying a high-temperature warm-up power (Pw) for 8 to 12 seconds to the heater immediately before the step d).

In addition, the step c) provides a gas concentration measuring method comprising the step of turning off the heater after a predetermined time (Ta), when the exhalation flows into the exhalation passage.

In addition, when the step c) is completed, a method for measuring the gas concentration that automatically enters the step d) is provided.

In addition, the present invention, the exhalation passage through which the exhalation flows, the sample gas chamber into which the sample gas, which is a part of the exhalation flowing through the exhalation passage in communication with the exhalation passage, is disposed inside the sample gas chamber, and A semiconductor gas sensor including a sensing unit generating an electric signal according to a concentration and a heater heating the sensing unit, and controlling the heater, and receiving an electrical signal from the semiconductor gas sensor to calculate the concentration of the gas to be measured In the gas concentration measuring device comprising a controller,

The controller comprises: a) a warm-up step of heating the sensing unit by applying power to the heater, and b) a measurement step of stabilization determining the resistance value of the sensing unit while the heater power Tm is applied to the heater. And, c) a measurement standby step of applying a heater power Tm to the heater after the exhalation flows into the exhalation passage, and d) when the exhalation flows into the exhalation passage, an electrical signal from the semiconductor gas sensor. It is configured to perform the step of calculating the concentration of the gas to be measured by receiving,

The controller, if it is determined in step b) that the sensing unit is stable, performs step d) after step b), and if it is determined in step b) that the sensing unit is unstable, after step b) the c It provides a gas concentration measuring device configured to sequentially perform steps) and d).

The gas concentration measuring apparatus according to the present invention has the advantage of being able to quickly and accurately measure the concentration of the gas to be measured at a low concentration.

1 is a configuration diagram of a gas concentration measuring apparatus according to an embodiment of the present invention.
2 is a flow chart of a gas concentration measurement method according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings. The embodiments introduced below are provided as examples to ensure that the spirit of the present invention is sufficiently transmitted to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below and may be embodied in other forms. In addition, in the drawings, the width, length, and thickness of components may be exaggerated for convenience. Throughout the specification, the same reference numbers refer to the same components.

1 is a configuration diagram of a gas concentration measuring apparatus according to an embodiment of the present invention. Referring to FIG. 1, the gas concentration measuring device is a semiconductor gas sensor 5 disposed inside the sample gas chamber 3 and the sample gas chamber 3 communicating with the exhalation passage 2, the exhalation passage 2. , A controller 6 and a display 7.

The exhalation passage 2 is in the form of a cylinder with both ends open. A blower 1 may be coupled to the inlet 23 of one end of the exhalation passage 2. The exhalation introduced into the exhalation passage 2 through the fire zone 1 is discharged to the outside through the outlet 24 of the other end of the exhalation passage 2. The outlet 24 is formed to an appropriate size so as not to apply excessive pressure in the exhalation passage 2. The outlet 24 may be made of a plurality of through holes. The discharge port 24 also serves to discharge saliva or the like of the person included in the exhalation to the outside.

In the exhalation passage 2, a sampling hole 21 for supplying a part of the exhalation introduced into the exhalation passage 2 to the sample gas chamber 3 is formed. A significant portion of the exhalation introduced into the exhalation passage 2 is discharged directly to the outside through the outlet 24, and a part is supplied to the sample gas chamber 3 through the sampling hole 21. The exhalation supplied through the sampling hole 21 among the exhalations flowing through the exhalation passage 2 is called a sample gas.

In addition, although not shown, a pressure sensor or a microphone may be installed in the exhalation passage 2 or the other tube communicating with the exhalation passage 2 to check whether the subject is blowing out the exhalation.

The sample gas chamber 3 is connected to the sampling hole 21 of the exhalation passage 2 through the sample gas inlet pipe 31. On the other side, a sample gas discharge pipe (33) is installed. A semiconductor gas sensor 5 is installed inside the sample gas chamber 3.

The resistance value of the semiconductor gas sensor 5 changes according to the concentration of the gas to be measured of the sample gas. For example, as the concentration of the gas to be measured increases, the resistance value decreases. Hereinafter, it will be described taking acetone as an example gas to be measured.

The semiconductor gas sensor 5 is equipped with a heater for heating the sensing unit and the sensing unit. For example, the semiconductor gas sensor 5 may include a ceramic substrate and an electrode pattern formed on both surfaces of the ceramic substrate, a heater pattern, and a sensing unit that is a sensing material of a thick film applied on the electrode pattern. The semiconductor gas sensor 5 can measure the concentration of acetone by measuring a change in the resistance value of the sensing unit through the electrode pattern. The resistance value can be measured by changing the current flowing through the sensing unit or the voltage between the sensing units.

The controller 6 serves to control a heater that heats the sensing portion of the semiconductor gas sensor. In addition, the controller 6 serves to calculate the acetone concentration value according to the electric signal value received from the semiconductor gas sensor 5.

The display unit 7 may be a display device that displays the acetone concentration value or the like calculated by the controller 6. In addition, the display unit 7 may further include a speaker for transmitting a warning signal.

Hereinafter, a gas concentration measuring method using the above-described gas concentration measuring apparatus will be described with reference to FIG. 2.

When the gas concentration measuring device is turned on and the start button is pressed, the controller 7 first determines how much time has passed since the previous acetone concentration measurement (S1).

In addition, if the elapsed time is a predetermined time, for example, 2 hours or less, the general warm-up step S2 proceeds, and if it exceeds this, the high-temperature warm-up step S3 proceeds.

If a long time has elapsed since the last acetone concentration measurement, the likelihood of contamination of the semiconductor gas sensor 5 in the sample gas chamber 3 increases because moisture and gas components in the outside air flow into the sample gas chamber 3. . In this case, in order to stabilize the semiconductor gas sensor 5, the process proceeds to a high-temperature warm-up step (S3) in which more energy is used, otherwise, to the general warm-up step (S2). The acetone contained in the exhalation has a very low concentration of several ppm, so the stabilization of the semiconductor gas sensor 5 is very important.

In the general warm-up step (S2), the heater power Tm of the measurement step is applied to the heater of the semiconductor gas sensor 5 for about 20 to 30 seconds. When the sensing unit is heated by the heater, oxygen gas is adsorbed on the surface of the thick film, which is the sensing unit, and free electrons are trapped in the oxygen gas, thereby increasing the resistance value of the sensing unit.

In the high-temperature warm-up step (S3), a high-temperature warm-up power (Pw) of 10 to 50% greater than the heater power Tm of the measurement step is applied to the heater of the semiconductor gas sensor 5 for about 20 to 60 seconds.

In the high-temperature warm-up step S3, the high-temperature warm-up power Pw may be applied to the entire step, but the high-temperature warm-up power Pw may be applied only in some sections, and the measurement step heater power Tm may be applied in the remaining sections. . For example, the high-temperature warm-up power Pw may be applied in the first 30 seconds, and the heater power Tm in the measurement step may be applied in the later 30 seconds.

Next, when the warm-up is completed, a stabilization determination step (S4) of measuring the resistance value of the sensing unit is performed in a state in which the heater power Tm is applied to the heater. In the stabilization determination step, for example, if the resistance value of the sensing unit is greater than or equal to a predetermined value, it is determined that the sensing unit is stable, and if it is less than a predetermined value, it is determined that it is unstable.

First, a measurement step in the case where the sensing unit is determined to be in an unstable state will be described.

When the stabilization determination step (S4) is completed, it is possible to inform the operator that warming up is completed through the display unit 7. Then, the measurer guides the subject to inhale the exhalation passage 2 through the fire 1.

Next, when the exhalation flows into the exhalation passage 2, the heater of the semiconductor type gas sensor 5 is turned off after a predetermined time (Ta) (S5). Whether the exhalation flows into the exhalation passage 2 can be confirmed through a pressure sensor or a microphone installed in the exhalation passage 2.

When the person to be measured blows the exhalation strongly into the exhalation passage 2, the exhalation flows into the exhalation passage 2, and a part of the exhalation flows into the sample gas chamber 3 and then passes through the sample gas discharge pipe 33. It is discharged to the outside. In this process, contaminants such as odor components remaining inside the sample gas chamber 3 are discharged to the outside of the sample gas chamber 3 with exhalation. In addition, as the contaminants attached to the surface of the sensing portion of the semiconductor gas sensor 5 are removed, oxygen is adsorbed to the sensing portion of the semiconductor gas sensor 5, and the resistance value of the sensing portion is significantly increased.

In this step, the user's exhalation contributes to the rapid stabilization of the semiconductor gas sensor 5 through the ventilation of the sample gas chamber 3 and the removal of contaminants adsorbed on the sensing portion of the semiconductor gas sensor 5. Without this process, it takes too long (more than 1 hour) to stabilize the semiconductor gas sensor 5 by only heating the sensing unit. In addition, if the sensing unit is heated for a long time, the sensing unit may deteriorate. In addition, in the case of a portable device, it may cause rapid consumption of the battery.

After the exhalation flows into the exhalation passage 2, the heater of the semiconductor gas sensor 5 is turned off when a predetermined time Ta passes. The predetermined time is about 3 to 7 seconds.

Next, the heater power Tm is automatically applied to the heater again to enter the measurement standby stage (S6).

If necessary, the high temperature warm-up power Pw may be applied for 8 to 12 seconds before applying the measurement step heater power Tm.

When the measurement waiting step is completed, the measurement unit is notified through the display unit 7 that the measurement is ready. The tester in turn causes the testee to breathe the exhalation passage 2 through the fire 1.

Next, when the sample gas is introduced again, the acetone concentration is measured (S7).

When the person to be breathed in the exhalation passage 2 in the measurement waiting step, the sample gas that is part of the exhalation flows into the sample gas chamber 3, and the resistance value of the sensing unit is changed by the acetone included in the exhalation. The controller 6 receives the electric signal according to the change of the resistance value, and measures the acetone concentration included in the exhalation. And based on this, it is also possible to calculate the concentration of acetone in the blood. In addition, the amount of body fat burned can be calculated based on the concentration of acetone in the blood.

Next, a case where the sensing unit is judged to be in a stable state will be described. When the detector is in a stable state, unlike the unstable state, the acetone concentration is measured immediately (S7) immediately after the stabilization determination step (S4). That is, the stabilization determination step (S4) also serves as a measurement waiting step. As described above, since the measurement step heater power Tm is applied in the stabilization determination step S4, it is not necessary to go through the measurement standby step again after the stabilization determination step S4.

In the gas concentration measuring method of the present invention, measurement may be completed in about 2 to 5 minutes.

The embodiments described above are merely illustrative of preferred embodiments of the present invention, and the scope of the present invention is not limited to the described embodiments, and those skilled in the art within the technical spirit and claims of the present invention. Various changes, modifications, or substitutions may be made by and it should be understood that such embodiments are within the scope of the present invention.

For example, it has been described that the process proceeds to a high-temperature warm-up step or a general warm-up step depending on the elapsed time after the recent measurement of acetone concentration, but depending on the use, the elapsed time may not be determined, and the process may proceed to the general warm-up step. Of course, it is also possible to proceed to the high temperature warm-up step regardless of the elapsed time.

In addition, although acetone has been described as an example, the gas concentration measuring apparatus and gas concentration measuring method of the present invention can be used even when other gases such as alcohol are used as the gas to be measured.

1: Buddha
2: exhalation passage
21: collection hole
23: inlet
24: outlet
3: Sample gas chamber
31: sample gas inlet pipe
33: sample gas discharge pipe
5: Semiconductor type gas sensor
6: Signal processing unit
7: Display

Claims (8)

An exhalation passage through which exhalation flows, a sample gas chamber in communication with the exhalation passage and sample gas which is a part of the exhalation flowing through the exhalation passage, and an electrical signal according to the concentration of the gas to be measured disposed in the sample gas chamber Gas concentration including a semiconductor gas sensor including a sensing unit for generating and a heater for heating the sensing unit, and a controller that controls the heater and receives an electric signal from the semiconductor gas sensor to calculate the concentration of the gas to be measured. As a gas concentration measuring method using a measuring device,
a) a warm-up step of applying the electric power to the heater to heat the sensing unit,
b) a stabilization determination step of measuring a resistance value of the sensing unit in a state in which a heater power Tm is applied to the heater;
c) the step of exhalation is introduced into the exhalation passage,
d) a measurement standby step of applying the heater power Tm to the measurement step,
e) when the exhalation flows into the exhalation passage, receiving an electrical signal from the semiconductor gas sensor and calculating the concentration of the gas to be measured,
If it is determined in step b) that the sensing unit is stable, step b) is followed by step e),
If it is determined in step b) that the sensing unit is unstable, the gas concentration measurement method in which steps c), d) and e) are sequentially performed after step b). According to claim 1,
The a) step is a gas concentration measurement method comprising a high temperature warm-up step of applying an accelerated warm-up power (Pw) 10 to 50% greater than the heater power Tm of the measurement step. According to claim 1,
The a) step is a gas concentration measurement method comprising a general warm-up step of applying a heater power (Tm) of the measuring step to the heater. According to claim 1,
Gas concentration measurement method further comprising the step of applying a high temperature warm-up power (Pw) to the heater immediately before the step d). According to claim 1,
The step d) immediately before the step of applying a high-temperature warm-up power (Pw) for 8 to 12 seconds to the gas concentration measurement method further comprises. According to claim 1,
The step c), when the exhalation flows into the exhalation passage, the gas concentration measurement method comprising the step of turning off the heater after a predetermined time (Ta). The method of claim 6,
When the step c) is finished, the gas concentration measurement method that automatically enters the step d). The exhalation passage through which the exhalation flows, the sample gas chamber through which the sample gas, which is a part of the exhalation flowing through the exhalation passage, communicates with the exhalation passage, is disposed inside the sample gas chamber, and generates an electrical signal according to the concentration of the gas to be measured. Gas concentration including a semiconductor gas sensor including a sensing unit for generating and a heater for heating the sensing unit, and a controller that controls the heater and receives an electric signal from the semiconductor gas sensor to calculate the concentration of the gas to be measured. In the measuring device,
The controller,
A) a warm-up step of heating the sensing unit by applying electric power to the heater,
B) a stabilization determination step of measuring the resistance value of the sensing unit in a state in which the heater power Tm is applied to the heater;
C) a measurement standby step of applying a heater power Tm to the heater after the exhalation flows into the exhalation passage;
D) when the exhalation flows into the exhalation passage, it is configured to perform the step of receiving the electrical signal from the semiconductor gas sensor and calculating the concentration of the gas to be measured,
The controller,
If it is determined in step b) that the sensor is stable, after step b), step d) is performed,
If it is determined in step b) that the detector is unstable, a gas concentration measuring device configured to sequentially perform steps c) and d) after step b).

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