Gas concentration correction system, gas measurement system, and gas concentration correction method

Abstract

The quantitative accuracy of gases is improved by enhancing the correction for quantitative values. [Solution] A gas concentration correction system according to one embodiment includes: a gas concentration value acquisition unit that acquires the gas concentration based on the output of the reaction value of the gas in the gas; a flow rate value acquisition unit that acquires the flow rate based on the output of a value related to the flow rate of the gas; a correction unit that corrects the gas concentration based on the flow rate and outputs a corrected concentration value indicating the corrected gas concentration; and a concentration output unit that outputs the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized.

Description

Technical Field

[0005] , ,

[0001] The present invention relates to a gas concentration correction system, a gas measurement system, and a gas concentration correction method.

Background Art

[0002] Gases such as exhaled breath and skin gas emitted from the bodies of animals or humans contain biological gases that are by-products of metabolism in the body. It is known that by analyzing the types and concentrations of biological gases in exhaled breath and skin gas, etc., it becomes possible to manage physical condition and detect latent diseases. Known biological gases include acetone, which is an indicator of diabetes and fat metabolism, ethanol, which is an indicator of epilepsy, ammonia, which is an indicator of kidney disease, CO, which is an indicator of smoking intensity, and H2, which is an indicator of the intestinal environment.

[0003] Analysis of biological gases is expected to be applied to daily monitoring and incorporated into portable devices because it is non-invasive and simple compared to analysis of liquids such as blood and saliva. For example, Patent Documents 1 to 4 disclose detection methods and detection devices for biological gases using gas sensors and odor sensors.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] Quantitative analysis of biological gases is required for health management and early detection of illness, but the methods and apparatus described in Patent Documents 1-4 either do not provide sufficient quantitative accuracy or have insufficient quantitative precision. While it might be possible to use pumps or fans to stabilize the amount of exhaled air intake for quantitative analysis, this would increase the overall size of the sensor system.

[0006] Since the subjects are expected to be men and women ranging from children to the elderly, the amount of exhaled breath will differ from person to person depending on their age, gender, etc. It is difficult to expect all subjects to exhale a sufficient amount of breath consistently onto the sensor, and it may be necessary to repeat the exhalation process. If this happens, the operability of the device will be significantly reduced. Patent Document 2 describes a method in which a flow velocity sensor is installed inside a case housing a gas sensor, the exhaled air volume is determined from the flow velocity sensor value, and the quantitative value of the gas is corrected using the exhaled air volume. If high quantitative accuracy can be achieved by correcting the quantitative value of the gas, it is thought that the system can be made larger and the operability can be reduced.

[0007] However, since flow velocity sensors can only measure the flow velocity around the sensor, the technology described in Patent Document 2 suffers from a significant decrease in quantitative accuracy when turbulence occurs within the sensor space. The above circumstances are not limited to the analysis of biological gases in exhaled breath, but also occur in the quantitative analysis of gases in other gases besides exhaled breath, such as skin gases.

[0008] In view of the above circumstances, the present invention aims to improve quantitative accuracy by improving the accuracy of corrections to the quantitative value of gas. [Means for solving the problem]

[0009] To solve the above problems, a gas concentration correction system according to one aspect of the present invention comprises: a gas concentration value acquisition unit that acquires a gas concentration based on the output of a reaction value of the gas in the gas; a flow rate value acquisition unit that acquires a flow rate based on the output of a value related to the flow rate of the gas; a correction unit that corrects the gas concentration based on the flow rate and outputs a corrected concentration value indicating the corrected gas concentration; and a concentration output unit that outputs the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized.

[0010] According to a gas concentration correction system according to one aspect of the present invention, the concentration output unit outputs the corrected concentration value as a representative value of the gas concentration in the gas when the fluctuation of the corrected concentration value falls within a predetermined fluctuation range. According to one aspect of the present invention, the gas concentration correction system acquires a flow rate value, which acquires a plurality of flow rates based on each of a plurality of measuring elements, and the correction unit corrects the gas concentration based on the flow rates when the plurality of flow rates are approximately equal. All components and functions of the system may be implemented in a mobile terminal device, or some components and functions of the system may be implemented in a mobile terminal device, and the remaining components and functions may be implemented in an external device connected to the mobile terminal device.

[0011] To solve the above problems, a gas measurement system according to one aspect of the present invention comprises: a flow path through which a gas containing the gas to be measured flows; a gas measuring element provided inside the flow path and outputting a reaction value of the gas in the gas; a flow rate measuring element provided inside the flow path and outputting a value related to the flow rate of the gas; a correction unit that corrects the gas concentration based on the output of the gas measuring element based on the flow rate based on the output of the flow rate measuring element and outputs a corrected concentration value indicating the corrected gas concentration; and a concentration output unit that outputs the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized.

[0012] According to one aspect of the present invention, the concentration output unit outputs the corrected concentration value as a representative value of the gas concentration in the gas when the fluctuation of the corrected concentration value falls within a predetermined fluctuation range. According to one aspect of the present invention, the gas measuring system comprises a gas intake port, a gas outlet port, a first space in contact with the intake port, and a second space in contact with the first space. The flow rate measuring element is provided on the wall surface of the flow path in the first space, and the gas measuring element is provided on the wall surface of the flow path in the second space. The area of ​​the cross-sectional area perpendicular to the direction of extension of the flow path in the second space is larger than the area of ​​the cross-sectional area perpendicular to the direction of extension of the flow path in the first space. According to one aspect of the present invention, the flow path has a third space that is in contact with the second space on one side and with the outlet on the other side, and the area of ​​the cross-sectional area perpendicular to the direction of extension of the flow path in the second space is larger than the area of ​​the cross-sectional area perpendicular to the direction of extension of the flow path in the third space.

[0013] According to one aspect of the present invention, in the direction of extension of the flow path, the conductance of the first space and the third space are approximately equal. According to one aspect of the present invention, the gas measuring element comprises a metal oxide as a gas-sensitive film, and measures the concentration of the gas based on the change in the resistance value of the gas-sensitive film due to an oxidation-reduction reaction.

[0014] To solve the above problems, a gas concentration correction method according to one aspect of the present invention includes the steps of: obtaining a gas concentration based on the output of a reaction value of the gas in the gas; obtaining a flow rate based on the output of a value related to the flow rate of the gas; correcting the gas concentration based on the flow rate and outputting a corrected concentration value indicating the corrected gas concentration; and outputting the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized. [Effects of the Invention]

[0015] According to the present invention, it is possible to improve the accuracy of correction for the quantitative value of gas and improve the quantification.

Brief Description of the Drawings

[0016] [Figure 1] It is a diagram showing a gas concentration measurement system. [Figure 2A] It is a diagram showing the appearance of a rectangular measuring instrument. [Figure 2B] It is a diagram showing the appearance of a smartphone jet-type measuring instrument. [Figure 3A] It is a cross-sectional view showing the conceptual internal structure of the measuring instrument. [Figure 3B] It is a cross-sectional view showing a more specific internal structure of the measuring instrument. [Figure 4] It is a graph showing the characteristics of gas concentration measurement by a gas sensor. [Figure 5] It is a block diagram showing the functional configuration of a gas concentration correction device. [Figure 6] It is a flowchart showing the processing operation in the gas concentration correction device. [Figure 7] It is a graph showing the gas concentration etc. obtained by the processing of the gas concentration correction device. [Figure 8A] It is a diagram showing the conceptual structure of a modified example provided with a plurality of flow velocity sensors. [Figure 8B] It is a cross-sectional view showing a more specific structural example of the modified example of FIG. 8A. <​​​​​​​​​​​​​​The embodiments of the present invention will be described in detail below with reference to the attached drawings. Note that the following embodiments are not limiting to the present invention, and not all combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be modified or changed as appropriate depending on the specifications and various conditions (operating conditions, operating environment, etc.) of the device to which the present invention is applied.

[0018] The technical scope of the present invention is defined by the claims and is not limited by the following individual embodiments. The drawings used in the following description may differ in scale and shape from the actual structure for the sake of clarity. For the sake of simplicity, there may be some parts of the drawings that do not strictly correspond to each other. Components shown in the drawings described earlier may be referenced as appropriate in later descriptions of the drawings.

[0019] <Gas concentration measurement system> Figure 1 shows a gas concentration measurement system. The gas concentration measurement system 100 corresponds to one embodiment of the gas measurement system of the present invention, and as an example, measures the concentration of biological gases contained in exhaled breath.

[0020] Possible biological gases to be measured include acetone, ethanol, ammonia, CO, and H2. The biological gas measured in this embodiment is not specified.

[0021] The gas concentration measurement system 100 comprises a measuring instrument 110, a gas concentration correction device 120, and a recording server 130. The gas concentration correction device 120 is an example of the gas concentration correction system of the present invention.

[0022] The measuring instrument 110 shown in Figure 1 is a cylindrical measuring instrument and comprises a main body 111, a mouthpiece 112, and a measurement start button 113. The main unit 111 is equipped with internal gas sensors for measuring the concentration of biological gases, as will be described later. The main unit 111 is also provided with a USB (Universal Serial Bus) port, which is not shown in the diagram, for charging and communication.

[0023] The mouthpiece 112 is used to blow exhaled air into the main body 111. The measurement start button 113 is pressed when the measurement of the biogas concentration begins. The gas concentration correction device 120 corresponds to one embodiment of the gas concentration correction system of the present invention, and is implemented, for example, in a mobile terminal device such as a smartphone. The gas concentration correction device 120 is connected to the measuring instrument 110, for example via USB, and acquires measured values ​​such as gas concentration from the measuring instrument 110. The gas concentration correction device 120 may also be wirelessly connected to the measuring instrument 110 using BLE (Bluetooth Low Energy) or the like. Hereafter, the term "measured value" may refer to the signal value output by sensors such as gas sensors and flow velocity sensors, which will be described later, or it may refer to the value obtained by correcting the output value with information about the surrounding environment such as humidity and temperature. Furthermore, the term "measured value" may also refer to the gas concentration or flow rate obtained using a calibration curve from the sensor output value or the corrected value of the sensor output value.

[0024] The recording server 130 is, for example, a cloud server and is connected to the gas concentration correction device 120 via a mobile network or the like. The recording server 130 records the measured gas concentration. The recording server 130 also stores calibration curves, etc., used to correct the gas concentration, as described later. Past measured values ​​recorded in the recording server 130 are provided to the gas concentration correction device 120 as needed for comparison of measured values, etc.

[0025] Figures 2A and 2B show the appearance of other types of measuring instruments that can be used as alternatives to the measuring instrument 110 shown in Figure 1. The measuring instrument 200 shown in Figure 2A is a rectangular measuring instrument. Similar to the measuring instrument 110 shown in Figure 1, the measuring instrument 200 shown in Figure 2A is equipped with a main unit 210, a mouthpiece 220, a measurement start button 230, and a USB port 240.

[0026] The measuring instrument 300 shown in Figure 2B is a smartphone gadget type measuring instrument. Similar to the measuring instrument 110 shown in Figure 1, the measuring instrument 300 shown in Figure 2B comprises a main unit 310, a mouthpiece 320, and a measurement start button 330, and is equipped with a USB connection terminal 340 for direct connection to the gas concentration correction device 120.

[0027] <Structure of the measuring instrument> The internal structure of measuring instruments 110, 200, and 300 will be explained, with the measuring instrument 110 shown in Figure 1 as a representative example, and with particular attention paid to the main body 111.

[0028] Figure 3A is a cross-sectional view showing the conceptual internal structure of the measuring instrument 110. The main body 111 of the measuring instrument 110 is a structure made of resin or the like, and is provided with a flow path 400. The flow path 400 is a passage for exhaled air and has an inlet 410 and an outlet 420. The cross-sectional shape of the flow path 400 in a cross section perpendicular to the direction of extension is, for example, a perfect circle. The cross-sectional shape of the flow path 400 may be a semicircle, an ellipse, a rectangle, etc. The flow path 400 is composed of three chambers (spaces), and has a structure in which the first space 430, the second space 440, and the third space 450 are connected. In this case, the inlet 410 is in contact with the first space 430, and the outlet 420 is in contact with the third space 450. It is not necessary for the flow path 400 to be divided into three chambers; it may be two or one. If the flow path consists of two chambers, the outlet 420 is in contact with the second space 440. If the flow path consists of one chamber, both the inlet 410 and the outlet 420 are in contact with the second space 440. If the flow path consists of one chamber, it contains both a flow velocity sensor and a gas sensor, which will be described later.

[0029] Exhaled air is blown into the first space 430 from the inlet 410. The first space 430 is equipped with a flow velocity sensor 460 that indirectly measures the flow rate by measuring the flow velocity of the exhaled air flowing through the flow path. The flow velocity sensor 460 corresponds to an example of a flow rate measuring element as described in the present invention. The flow velocity sensor 460 is electrically connected to a circuit board (not shown). The flow rate of the exhaled air is determined as the product of the flow velocity and the flow path cross-sectional area of ​​the first space 430, and the flow path cross-sectional area of ​​the first space 430 is a fixed value. The flow path cross-sectional area is determined from a cross section perpendicular to the direction of extension of the flow path. Therefore, the flow velocity measured by the flow velocity sensor 460 is used as a value that substantially indicates the flow rate.

[0030] The second space 440 is, for example, a space with a larger flow path cross-sectional area than the first space 430, and the second space 440 is equipped with a gas sensor 470 for measuring the concentration of biological gases or gases contained in exhaled breath, such as alcohol. The gas sensor 470 is electrically connected to a circuit board (not shown). The gas sensor 470 may also be a so-called odor sensor, having multiple sensor parts with different sensitivities to multiple types of gases, and capable of measuring the type and concentration of gas.

[0031] In the first space 430, a small flow path cross-sectional area results in laminar exhalation flow, improving the accuracy of flow velocity measurement by the flow velocity sensor 460. In contrast, in the second space 440, a large flow path cross-sectional area results in slower exhalation flow, improving the accuracy of gas concentration measurement by the gas sensor 470. In particular, when a semiconductor sensor using a metal oxide for the sensitive membrane is used as the gas sensor 470, the configuration of the first space 430 and the second space 440 shown in Figure 3A is preferable because it makes it less likely for exhalation to directly hit the gas sensor 470, reducing the flow velocity near the sensitive membrane and improving sensor sensitivity.

[0032] The third space 450 is, for example, a space with a smaller flow path cross-sectional area than the second space 440. Exhaled air flows out of the third space 450 to the outside of the measuring instrument 110 via the outlet 420. Also, if turbulence occurs in the exhaled air, outside air flows into the third space 450 from the outlet 420. If the flow path cross-sectional area of ​​the third space 450 is small, the flow of exhaled air is stabilized and the inflow of outside air is suppressed. In particular, if the conductance of the third space 450 is approximately the same as that of the first space 430, the inflow and outflow of exhaled air to the second space 440 are balanced, resulting in a high degree of stability of the exhaled air flow and a high effect of suppressing the inflow of outside air.

[0033] Conductance is an indicator of how easily a fluid flows and is defined by the following equation. Q=C(ΔP) C: Conductance Q:Flow rate ΔP: Pressure difference within the flow path If we assume that the flow path is a cylinder with a cross-sectional radius a and length L, and that the fluid is air, then C = (a^3) / L. In other words, for a cylindrical flow path, the larger the cross-section and the shorter the length, the easier the fluid will flow.

[0034] Figure 3B is a cross-sectional view showing a more specific internal structure of the measuring instrument 110. The measuring instrument 110 has a main body 510 which is a structural part, and the main body 510 is made of, for example, PTFE (polytetrafluoroethylene). A first printed circuit board 520 and a second printed circuit board 540 are arranged inside this main body 510, and a portion of the surfaces of these printed circuit boards 520 and 540 forms the walls that create the flow path. A gas sensor 530 is mounted on the first printed circuit board 520, and a flow velocity sensor 560 is mounted on the second printed circuit board 540. The second printed circuit board 540 overlaps the first printed circuit board 520, and the first printed circuit board 520 and the second printed circuit board 540 are electrically connected by a connector 550. This connector 550 creates a step between the surfaces of the two printed circuit boards 520 and 540. To create a step, components such as leads may be used to connect the two printed circuit boards 520 and 540, or the printed circuit boards 520 and 540 may be attached separately to the main body 510 by adhesive, snap-in, or the like.

[0035] The gas sensor 530 is not limited in its measurement principle, and can be of any type, such as oscillator, semiconductor, or electrochemical. The semiconductor sensor uses an oxide semiconductor as a sensitive film for biological gases and measures the concentration of biological gases based on the change in the resistance of the sensitive film due to oxidation-reduction reactions. The material of this sensitive film can be an oxide semiconductor among metal semiconductors, and materials such as tin oxide or tungsten oxide can be used. The flow velocity sensor 560 is, for example, a MEMS (Micro Electro Mechanical Systems) type thermocouple.

[0036] The first printed circuit board 520 and the second printed circuit board 540 narrow the internal space of the main body 510, forming the first space 430. In addition, the internal space of the main body 510 is narrowed at the portion of the first printed circuit board 520 that does not overlap with the second printed circuit board 540, forming the second space 440. The third space 450 is the same as the internal space of the main body 510. In this way, the surfaces of the printed circuit boards 520 and 540 become flow channels, and the volumes and flow channel cross-sectional areas of the multiple chambers can be made different, so that the quantitative accuracy of gas concentration can be improved while miniaturizing the measurement unit 110.

[0037] Figure 4 is a graph showing the characteristics of gas concentration measurement using a gas sensor. This is an illustration to illustrate the invention. The horizontal axis of Figure 4 shows the exhalation flow rate [sccm], and the vertical axis shows the gas concentration [ppm] measured by the gas sensor. The unit of flow rate, sccm, is an abbreviation for "Standard Cubic Centimeters per Minute," and is a unit that indicates the flow rate in cubic centimeters per minute under standard conditions. Specifically, it is a unit used when measuring the flow rate of a gas, and is based on the volumetric flow rate under standard conditions (usually 0°C and 1 atmosphere). In the unsaturated region 610, where the exhaled airflow rate is low, the second space 440 is not saturated with exhaled air. Therefore, the concentration of biological gases in the second space 440 does not reach the concentration of biological gases contained in the exhaled air. As a result, the measured gas concentration changes according to the exhaled airflow rate, showing a linear relationship as shown in Figure 4 as an example. The inventors investigated and confirmed that the exhaled airflow rate and the output of the gas sensor are monotonically increasing. The output of the gas sensor and the gas concentration were linear. Therefore, although the linear relationship is not as clear as shown in Figure 4, it was confirmed that it is possible to create a calibration curve showing the relationship between exhaled airflow rate and gas concentration.

[0038] On the other hand, in the saturation region 620, the measured gas concentration value is a constant value independent of the exhaled airflow rate. Therefore, at first glance, it appears that measuring in the saturation region 620 improves the accuracy of gas concentration measurement. However, the airflow rate required to reach the saturation region 620 is so high that it is difficult for children and the elderly to achieve. Furthermore, reaching the saturation region 620 requires continuous exhalation, which is necessary for about 10 seconds with commercially available breath sensors. Consequently, requiring measurement in the saturation region 620 makes the gas concentration measurement system 100 difficult to operate. In addition, when exhaling at a high flow rate into the measuring instruments 110, 200, and 300, saliva and other substances may mix with the exhaled air and adhere to the gas sensor 470, potentially negatively affecting the measurement.

[0039] Therefore, it is desirable to measure the gas concentration at a flow rate in the non-saturated region 610, and it is necessary to correct the measured gas concentration value based on the exhaled air flow rate. In the case of the gas concentration measurement system 100 shown in Figure 1, the measured gas concentration value is corrected by the gas concentration correction device 120.

[0040] <Gas concentration correction device> Figure 5 is a block diagram showing the functional configuration of the gas concentration correction device 120. The gas concentration correction device 120 includes a measurement value acquisition unit 121, a calibration curve acquisition unit 122, a concentration correction unit 123, and a concentration output unit 124.

[0041] The measurement value acquisition unit 121 acquires the output signals of the gas sensor 470 and the flow velocity sensor 460 from the measuring instruments 110, 200, and 300, and acquires the measured values ​​of the gas sensor 470 and the flow velocity sensor 460. The measurement value acquisition unit 121 may also acquire gas sensor correction information such as temperature or relative humidity output from a temperature sensor or humidity sensor installed in the flow path, and acquire measured values ​​with the gas sensor output signals corrected. Other information may be used as gas sensor correction information. The signal output value of the flow velocity sensor 460 is converted to flow rate by multiplying it by the cross-sectional area of ​​the flow path. Alternatively, a flow sensor may be provided instead of the flow velocity sensor 460, and instead of determining the flow rate from the flow velocity, the signal output value of the flow sensor may be adopted as the flow rate in subsequent flows. The calibration curve acquisition unit 122 acquires a first calibration curve showing the relationship between the measured value of the gas sensor 470 and the gas concentration, and a second calibration curve showing the relationship between the gas concentration and the exhaled air flow rate from the recording server 130. The first and second calibration curves are measured in advance, for example, during the manufacturing of the measuring instruments 110, 200, and 300, and stored in the recording server 130.

[0042] The first calibration curve is a conversion curve between the measured value of the gas sensor 470 and the gas concentration. For example, in the case of a semiconductor sensor, assuming that the temperature and humidity are nearly constant, if the selectivity for the gas to be measured is sufficiently high, or if the concentration of interfering gases other than the target gas is sufficiently low, the measured value of the gas sensor 470 and the gas concentration have the following relationship. Measured value ∝ gas concentration^s (where s is a constant) A calibration curve can be created based on the relationship described above. Even with sensors using other measurement principles, a relationship can be established between the sensor's signal output value and the gas concentration, making calibration curves possible. Although exhaled breath contains multiple types of gases, using multiple sensors with different gas selectivity allows for the calculation of the target gas concentration from the regression curve of the signal output values ​​of each sensor, thus enabling the creation of a calibration curve. Using multiple sensors is preferable because it improves the accuracy of gas concentration measurement.

[0043] The second calibration curve is a correction curve for gas concentration based on exhalation flow rate. Since it is difficult to measure the flow rate dependence in actual human exhalation, a simulated environment of exhalation is used to create the second calibration curve. After purifying air generated by an air compressor with an air purifier, this air is sent into a constant-temperature water bath to generate bubbles, thereby reproducing the flow rate, temperature, and humidity of human exhalation. Alternatively, by dissolving an arbitrary chemical substance in humidifying water and then sending air through the bath while stirring to generate bubbles, exhalation containing the target gas can be reproduced.

[0044] The concentration correction unit 123 determines the gas concentration from the measurement value of the gas sensor 470 using the first calibration curve and corrects the gas concentration using the second calibration curve. The concentration output unit 124 determines whether the corrected gas concentration can be considered an accurate measured value. Specifically, the concentration output unit 124 determines the corrected gas concentration in the section where the corrected gas concentration is stable over time as the true gas concentration and outputs it.

[0045] The following describes the processing operation of the gas concentration correction device 120 with reference to the flowchart. Figure 6 is a flowchart showing the processing operation in the gas concentration correction device 120. Figure 7 is a graph showing the gas concentration and other values ​​obtained from the processing in the gas concentration correction device 120. In Figure 7, the horizontal axis represents time, and the vertical axis represents measured values ​​such as gas concentration.

[0046] In step S101, the measurement start buttons 113, 230, and 330 of the measuring instruments 110, 200, and 300 are pressed by the user (subject) or the like, and the user begins exhaling. Then, the calibration curve acquisition unit 122 acquires the first calibration curve and the second calibration curve from the recording server 130. Note that the first calibration curve and the second calibration curve may have been acquired and stored in the gas concentration correction device 120 in advance prior to the process shown in the flowchart of Figure 6. In step S102, the user blows exhaled air into measuring instruments 110, 200, and 300. The flow rate of the exhaled air should preferably be below a predetermined specified flow rate so that it falls within the non-saturation region 610 shown in Figure 4. The gas concentration correction device 120 may issue a warning if the exhaled air is blown into measuring instruments 110, 200, and 300 at a flow rate exceeding the specified flow rate.

[0047] In step S103, the measurement value acquisition unit 121 acquires signals from the measuring instruments 110, 200, and 300 indicating the measured value of the gas sensor 470 and the flow rate indicated by the measured value of the flow velocity sensor 460. The signals and flow rates from the gas sensor 470 are acquired as time-dependent data that changes over time as exhaled air flows in. The acquired flow rate increases from zero over time, as shown in, for example, the first graph 710 in Figure 7, and once it reaches a certain flow rate, it is maintained while fluctuating. Fluctuations in the exhaled air flow rate may occur unintentionally and naturally, or they may be caused to some extent intentionally.

[0048] In step S104, the concentration correction unit 123 converts the signal value from the gas sensor 470 into a gas concentration based on the first calibration curve. The gas concentration obtained from the conversion increases from zero over time, as shown in the second graph 720 in Figure 7, for example, and once it reaches a certain gas concentration, it is maintained while fluctuating.

[0049] In step S105, the concentration correction unit 123 corrects the gas concentration based on the second calibration curve using the exhaled air flow rate. The corrected gas concentration increases from zero over time, as shown in, for example, the third graph 730 in Figure 7, and the concentration value is unstable in the unstable region 740. The unstable region 740 is a time period of about 2 seconds from the start of measurement. This unstable region 740 is thought to be the time interval required for, for example, the temperature of the flow velocity sensor 460 to match the temperature of the exhaled air, or for the exhaled air flow to stabilize.

[0050] Once the unstable region 740 is passed and the system enters the stable region 750, the corrected gas concentration stabilizes and shows the true gas concentration value. In step S106, the concentration output unit 124 confirms that the corrected gas concentration value has stabilized to a constant value. The concentration output unit 124 determines that the system is stable, for example, when the fluctuation in gas concentration falls within a variation range of ±0.5 ppm.

[0051] In step S107, the concentration output unit 124 outputs the time-averaged value of the corrected gas concentration in the stable region 750 as the true gas concentration value. In other words, it is output as a representative value of the gas concentration. This representative value can be displayed on the display unit as a quantitative value, or it can be stored in memory as the true gas concentration and later displayed on the display unit as a quantitative value. Alternatively, this representative value can be compared with a pre-stored threshold value, and the user can be notified of the disease diagnosis result on the display unit or elsewhere. As described above, since the true gas concentration value can be output, a highly quantitative breath sensor can be realized. By confirming the stability of the corrected gas concentration even when the exhaled airflow rate fluctuates and the measured gas concentration also fluctuates, it is confirmed that the effects of flow rate fluctuations and other factors are correctly corrected, resulting in highly accurate gas concentration measurement.

[0052] <Examples of measuring instruments> Next, we will describe modified versions of the measuring instrument 110 shown in Figures 3A and 3B. In the following explanation, we will focus on the differences from the measuring instrument 110 shown in Figures 3A and 3B, and will omit redundant explanations of equivalent parts.

[0053] Figures 8A to 8C show modified examples equipped with multiple flow velocity sensors. Figure 8A shows a conceptual structure, while Figures 8B and 8C show more specific structural examples. Figure 8B shows a cross-sectional view along the exhalation flow path 400, and Figure 8C shows a cross-sectional view perpendicular to the exhalation flow path 400.

[0054] In the modified configuration shown in Figures 8A to 8C, two flow velocity sensors 461 and 462 are provided within the first space 430. The number of flow velocity sensors 461 and 462 is not limited to two. The flow velocity sensors 461 and 462 are provided at different locations within the first space 430, and it is particularly preferable that they be provided on both sides of the central part of the flow path. By providing multiple flow velocity sensors 461 and 462 in this arrangement, it becomes possible to confirm whether the exhaled air flowing through the first space 430 is laminar.

[0055] If the measured values ​​of the multiple flow velocity sensors 461 and 462 are nearly identical, it can be determined that the exhaled air is flowing laminarly. If the difference in the measured values ​​exceeds a predetermined level, it can be determined that the exhaled air is flowing turbulently. Therefore, measuring the gas concentration while the exhaled air is flowing laminarly improves the accuracy of the measurement. If the exhaled air is flowing turbulently, the gas concentration correction device 120 may issue a warning.

[0056] As a specific example of a modified configuration equipped with multiple flow velocity sensors, as shown in Figures 8B and 8C, two flow velocity sensors 561 and 562 are provided on a second printed circuit board 540. In this case, the flow velocity sensors 561 and 562 are positioned above the surface of the second printed circuit board 540, lifted by a support 563.

[0057] Figures 9A and 9B show other modifications that incorporate multiple flow velocity sensors. Figure 9A shows a conceptual structure, and Figure 9B shows a more specific structural example. In the modified examples shown in Figures 9A and 9B, flow velocity sensors 464 and 465 are provided in the first space 430 and the third space 450, respectively. That is, flow velocity sensors 464 and 465 are provided on the upstream and downstream sides of the exhaled air, separated by the second space 440. Even when multiple flow velocity sensors 464 and 465 are provided in this arrangement, it is possible to confirm whether or not the exhaled air flow is laminar.

[0058] If the measurements from flow velocity sensors 464 and 465 are nearly identical on the upstream and downstream sides of the exhaled breath, it can be determined that the exhaled breath is flowing in a laminar manner. If the difference in the measurements exceeds a predetermined level, it can be determined that the exhaled breath is flowing in a turbulent manner. Therefore, measuring the gas concentration while the exhaled breath is flowing in a laminar manner improves measurement accuracy.

[0059] As a specific example of a modified configuration in which flow velocity sensors 464 and 465 are provided in the first space 430 and the third space 450, as shown in Figure 9B, a first printed circuit board 520, a second printed circuit board 541, and a third printed circuit board 542 are arranged inside the main body 510. A gas sensor 530 is mounted on the first printed circuit board 520, and flow velocity sensors 564 and 565 are mounted on the second printed circuit board 541 and the third printed circuit board 542, respectively. The second printed circuit board 541 and the third printed circuit board 542 overlap the first printed circuit board 520, and the first printed circuit board 520 is connected to the second printed circuit board 541 and the third printed circuit board 542, respectively, by connectors 551 and 552.

[0060] The first printed circuit board 520 and the second printed circuit board 541 narrow the internal space of the main body 510, forming the first space 430. In addition, the area of ​​the first printed circuit board 520 where the second printed circuit board 541 and the third printed circuit board 542 do not overlap narrows the internal space of the main body 510, forming the second space 440. Furthermore, the first printed circuit board 520 and the third printed circuit board 542 narrow the internal space of the main body 510, forming the third space 450.

[0061] This structure allows for the easy formation of a flow path having a first space 430, a second space 440, and a third space 450, contributing to the miniaturization of the measuring instrument 110. Although the above description exemplifies the application to measuring the concentration of biological gases contained in exhaled breath, the gas measurement system and gas concentration correction system of the present invention may also be applied to measuring the concentration of gases other than biological gases, or to measuring the concentration of gases contained in gases other than exhaled breath, such as skin gases.

[0062] Furthermore, although the above description shows an example in which a user blows their breath into the measuring instrument, in the gas measuring system of the present invention, gas collected in, for example, a plastic bag may be poured into the measuring instrument. Furthermore, although the above description shows an example in which the gas concentration correction system of the present invention is implemented using a smartphone, the gas concentration correction system of the present invention may also be implemented using a smartphone and a cloud server, for example, with the concentration output unit located on a cloud server. In this case, the determination by the concentration output unit may be performed after all time-dependent data of the measured values ​​have been measured and acquired. [Explanation of symbols]

[0063] 100 Gas Concentration Measurement System 110, 200, 300 Measuring Instruments 120 Gas concentration correction device 121 Measurement Value Acquisition Unit 122 Calibration curve acquisition section 123 Density correction section 124 Concentration output section 130 Recording Server 400 flow paths 410 Inlet 420 Outlet 430 The first space 440 The second space 450 The Third Space 460, 461, 462, 464, 465, 560, 561, 562, 564, 565 Flow velocity sensor 470, 530 Gas Sensors 510 Main Unit 520 First Printed Circuit Board 540, 541 Second printed circuit board 542 Third Printed Circuit Board 550, 551, 552 connectors 563 Support

Claims

1. A gas concentration value acquisition unit that acquires the gas concentration based on the output of the reaction value of the gas in the gas, A flow rate value acquisition unit that acquires the flow rate based on the output of a value related to the flow rate of the gas, A correction unit corrects the gas concentration based on the flow rate and outputs a corrected concentration value indicating the corrected gas concentration. A concentration output unit that outputs the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized, A gas concentration correction system equipped with the following features.

2. The gas concentration correction system according to claim 1, wherein the concentration output unit outputs the corrected concentration value as a representative value of the gas concentration in the gas when the fluctuation of the corrected concentration value falls within a predetermined fluctuation range.

3. The flow rate value acquisition unit acquires multiple flow rates based on each of the multiple measuring elements as the flow rate. The gas concentration correction system according to claim 1 or 2, wherein the correction unit corrects the gas concentration based on the flow rates when the plurality of flow rates are substantially equal.

4. The gas concentration correction system according to claim 1, wherein the gas concentration value acquisition unit, the flow rate value acquisition unit, the correction unit, and the concentration output unit are provided in a single portable terminal or in a device that can be connected to the portable terminal.

5. A flow path through which a gas containing the gas to be measured flows, A gas measuring element provided inside the flow path, which outputs a reaction value of the gas in the gas, A flow rate measuring element provided inside the flow path, which outputs a value related to the flow rate of the gas, A correction unit that corrects the gas concentration based on the output of the gas measuring element based on the flow rate based on the output of the flow rate measuring element, and outputs a corrected concentration value that shows the corrected gas concentration, A concentration output unit that outputs the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized, A gas measurement system equipped with the following features.

6. The gas measurement system according to claim 5, wherein the concentration output unit outputs the corrected concentration value as a representative value of the gas concentration in the gas when the fluctuation of the corrected concentration value falls within a predetermined fluctuation range.

7. The flow path has an intake port for the gas, an outlet port for the gas, a first space in contact with the intake port, and a second space in contact with the first space. The flow rate measuring element is provided on the wall surface of the flow path in the first space, The gas measuring element is provided on the wall surface of the flow path in the second space, The gas measurement system according to claim 5, wherein the area of ​​the cross-section perpendicular to the direction of extension of the flow path in the second space is larger than the area of ​​the cross-section perpendicular to the direction of extension of the flow path in the first space.

8. The gas measurement system according to claim 7, wherein the flow path has a third space that is in contact with the second space on one side and in contact with the outlet on the other side, and the area of ​​the cross-sectional area in the second space perpendicular to the direction of extension of the flow path is larger than the area of ​​the cross-sectional area in the third space perpendicular to the direction of extension of the flow path.

9. The gas measurement system according to claim 8, wherein in the direction of extension of the flow path, the conductance of the first space and the third space are approximately equal, which is an indicator of the ease of fluid flow.

10. The gas measuring system according to any one of claims 5 to 7, wherein the gas measuring element comprises a metal oxide as a gas-sensitive film, and the concentration of the gas is measured based on the change in the resistance value of the sensitive film due to an oxidation-reduction reaction.

11. A step of obtaining the gas concentration based on the output of the reaction value of the gas in the gas, The steps include obtaining the flow rate based on the output of a value related to the flow rate of the aforementioned gas, The steps include correcting the gas concentration based on the flow rate and outputting a corrected concentration value that shows the corrected gas concentration, The steps include: outputting the corrected concentration value as a representative value of the gas concentration in the gas when the corrected concentration value has stabilized; A method for correcting gas concentration.

Images