Method, control unit and device for detecting a gaseous substance in a gas mixture

Abstract

Method (100) for detecting a gaseous substance, in particular ethanol, in a gas mixture using a gas sensor, with • a first detection step (101) in which at least one first measured quantity (K1) representing a first chemical and / or physical parameter of the gas mixture, in particular a concentration of ethanol, is detected by a first sensor element (4), • a second detection step (102) in which at least one second chemical and / or physical parameter of the gas mixture, in particular a temperature, a pressure or a humidity, which is different from the first chemical and / or physical parameter, is detected by a second sensor element (5), • a first comparison step (103) in which it is compared whether an absolute value of a time derivative of the first measurement quantity (K1) exceeds a first predetermined threshold (SW1) and whether an absolute value of a time derivative of the second measurement quantity (M) exceeds a second predetermined threshold (SW2), • a first determination step (104) in which a start time (t S ) and one at the start time (t S ) corresponding initial measurement (K Start ) of the first chemical and / or physical parameter is determined if the first comparison (103) is positive, • a third acquisition step (105) in which at least one further first measurement (K2) is acquired, • a second comparison step (106) in which it is compared whether at least one further first measurement quantity (K2) of the initial measurement quantity (K Start ) corresponds, • a second determination step (107) in which an end time (t E ) is determined if the second comparison (106) is positive, • a third comparison step (108) in which it is compared whether the amount of a difference between the end time (t E ) and the start time (t S ) greater than a specified minimum time interval (t) min ) is, and • a signal generation step (109) in which an output signal (10) is generated if the third comparison (108) is positive.

Description

[0001] The invention is based on a method, a control device and a device according to the class of the independent claims. State of the art

[0002] Breath gas analyzers can analyze the composition and, in particular, the odor of a breath gas using chemical or physical sensors. Among other things, the alcohol content of the breath gas is also of interest.

[0003] From US 2004 / 0 081 582 A1 a mobile phone is known which is equipped with a respiratory gas sensor to show a user of the mobile phone the quality of his breath.

[0004] US 2014 / 0 357 963 A1 discloses a portable electronic device with an optical sensor by which an alcohol concentration of a breath gas can be detected.

[0005] From DE 10 2015 203 719 A1 a device for respiratory gas analysis is known, comprising a sensor element for detecting at least one analyte in a respiratory gas condensate volume.

[0006] DE 26 10 578 A1 discloses a method for determining the alcohol content in exhaled air, wherein a value of the alcohol concentration determined in the exhaled air is further processed if a temporal change in the alcohol content is below a predetermined threshold value.

[0007] DE 27 46 078 A1 discloses an arrangement for determining the concentration of reducing mouth gases, in particular the alcohol concentration of the breath, wherein the measured gas concentration is displayed when the temporal change in the gas concentration is less than or equal to a predetermined threshold value. Disclosure of the invention

[0008] Against this background, the approach presented here proposes a method for detecting a gaseous substance, in particular ethanol, in a gas mixture using a gas sensor, a control unit for implementing the method, and a gas sensor. The gas sensor can be designed as a mobile, handheld device with which a user can determine the alcohol or ethanol concentration in their breath. For this purpose, the gas sensor can advantageously have an opening into which the user can blow or breathe.

[0009] In the method, at least one first measured variable is initially recorded by a first sensor element and at least one second measured variable is recorded by a second sensor element. The first measured variable represents a first chemical and / or physical parameter of the gas mixture, in particular a concentration of ethanol. The first sensor element can be designed as a gas sensor, in particular as a resistive, capacitive, potentiometric and / or amperometric gas sensor. The second measured variable represents a second chemical and / or physical parameter of the gas mixture that is different from the first chemical and / or physical parameter, in particular a temperature, a humidity or a pressure. The second sensor element can be designed as a temperature sensor, a humidity sensor and / or a pressure sensor.Alternatively or additionally, it is possible that the first and / or the second sensor element is configured to detect at least two different measured variables, wherein the two different measured variables each represent two different chemical and / or physical parameters of the gas mixture.

[0010] To determine the start time of a measurement, a time derivative of the recorded first measured variables can be calculated and compared with a first predefined threshold value. By calculating a time derivative of the recorded second measured variables and comparing them with a second predefined threshold value, the accuracy with which the start time of the measurement is determined can be advantageously increased. This makes the measurement overall more reliable and robust against external influencing factors, such as changes in the composition of the gas mixture.

[0011] Simultaneously with the determination and storage of the start time, a first measured variable recorded at the start time is stored. Subsequently, further first measured variables are recorded, preferably continuously. The measurement is terminated when one of the further recorded first measured variables essentially corresponds to the first measured variable stored at the start time, by storing an end time corresponding to the further first measured variable.

[0012] A difference is then calculated between the end time and the start time, and the value of this difference is compared with a predefined minimum time period. The difference corresponds to a quantitative indication of the chemical and / or physical parameter of the gas mixture represented by the first measured variable. If the difference corresponds to the predefined minimum time period or exceeds the predefined minimum time period, an output signal is generated indicating that the first measured variable, which represents the first chemical and / or physical parameter of the gas mixture, is above a predefined threshold.

[0013] If now optionally a third measured variable or additionally a fourth measured variable is recorded, wherein the third measured variable and the fourth measured variable each represent a further chemical and / or physical parameter of the gas mixture, in particular a temperature, a humidity or a pressure, and wherein the parameters represented by the first measured variable, the second measured variable, the third measured variable and the fourth measured variable differ, and if a time derivative is formed for each additionally recorded measured variable and compared with a further predetermined threshold value, the accuracy with which the start time of the measurement is determined can be increased even further.

[0014] Optionally, it can be provided that the measurement is terminated when a relative deviation of the amount between the at least one further first measured variable and the first measured variable recorded at the start time is less than a predetermined threshold value, preferably less than 5%, particularly preferably less than 1% and most preferably less than 0.1%.

[0015] The advantages mentioned above also apply to the control unit for carrying out the process and the gas sensor.

[0016] Further advantages emerge from the following description of embodiments and from the dependent patent claims. Short description of the drawings

[0017] The Fig. 1 shows a schematic block diagram of a control unit. In Fig. Figure 2 shows a schematic diagram of a gas sensor. Fig. 3, the process is described using a flow chart. A graphical representation of a time course of measured variables representing temperature, humidity, and ethanol concentration of a gas mixture is shown in Fig. 4 shown. In Fig. 5 are graphical representations of a time course of time derivatives of the Fig. 3 shown measured values. Fig. Figure 6 shows a graphical representation of a measurement of ethanol concentration in a breath gas over time without prior alcohol consumption by a user. Fig. Figure 7 shows a graphical representation of a measurement of an ethanol concentration in a breath gas over time with previous alcohol consumption by the user. Example

[0018] As already stated above, the present invention describes a method, a control unit and a device which increases the accuracy in determining a starting time in a measurement of at least one gaseous substance in a gas mixture, in particular ethanol, and thus improves the accuracy of the measurement overall.

[0019] To carry out the method, a control unit 1 is provided as shown in Fig. 1 is shown schematically. This control unit 1 detects a first measured variable K representing an ethanol concentration of a respiratory gas by a first sensor element 4 and a second measured variable M representing another physical and / or chemical parameter of the respiratory gas, for example a temperature, by a second sensor element 5.

[0020] Optionally, it can be provided that the control unit 1 additionally detects a third measured variable N representing a further physical and / or chemical parameter of the respiratory gas, for example a humidity, by a third sensor element 6 and / or a fourth measured variable O representing a further physical and / or chemical parameter of the respiratory gas, for example a pressure, by a fourth sensor element 7.

[0021] The recorded measured variables K, M, N and O can be stored in a memory unit 3 of the device 1 if required.

[0022] The first sensor element 4 can be designed as a gas sensor, in particular as a resistive, capacitive, potentiometric, and / or amperometric gas sensor. The second sensor element 5 can be configured as a temperature sensor. The third sensor element 6 can be designed as a humidity sensor. The fourth sensor element 7 can be designed as a pressure sensor. Alternatively or additionally, it is possible for one of the sensor elements 4, 5, 6, 7 to be configured to detect at least two different measured variables, wherein the two different measured variables each represent two different chemical and / or physical parameters of the gas mixture.

[0023] The control unit 1 and the first sensor element 4 as well as the second sensor element 5 can, as in Fig. 2, form a gas sensor 20. Optionally, the gas sensor can additionally have a third sensor element 6 and / or a fourth sensor element 7. Furthermore, the sensor elements 4, 5, 6, 7 can be arranged or integrated on the gas sensor.

[0024] Based on the acquired measured variables K and M, as well as the optionally acquired measured variables N and O, a computing unit 2 in the control unit 1 executes the method 100 described below and, depending on the acquired measured variables K, M, N, and O, generates an output signal 10 which, for example, controls an acoustic signal generator 8. Optionally, a further output signal 11 can be generated which controls an optical signal generator 9. The acoustic signal generator 8 can be designed as a loudspeaker. The optical signal generator 9 can be configured as a light-emitting diode and / or as a display.

[0025] Using the flow chart of the Fig. 3, the method 100 is described in a preferred embodiment. First, in a first acquisition step 101, the first measured variable K is acquired, which represents an ethanol concentration in a respiratory gas.

[0026] Before, during, or after the detection step 101, a second detection step 102 takes place, in which a temperature of the respiratory gas is detected as the second measured variable M. Optionally, in the detection step 101, a humidity of the respiratory gas can also be detected as a third measured variable N and / or a pressure as a fourth measured variable O.

[0027] Now, in a subsequent first comparison step 103, an amount of the time derivative of the detected first measured variable K is compared with the threshold value SW1 and an amount of the time derivative of the detected second measured variable M is compared with the threshold value SW2.

[0028] Optionally, in comparison step 103, the magnitude of the temporal derivative of the acquired third measured variable N is additionally compared with the threshold value SW3. Optionally, in comparison step 103, the magnitude of the temporal derivative of the acquired fourth measured variable O is additionally compared with the threshold value SW4.

[0029] If the amount of the time derivative of the first measured variable K is above the first threshold value SW1 and the amount of the time derivative of the second measured variable M is above the second threshold value SW2, a starting time t S and one at the start time t S corresponding starting measured value K Start set.

[0030] Optionally, it can be provided that the first determination step 104 only takes place when, in addition, the amount of the time derivative of the third measured variable N is above the third threshold value SW3 and / or the amount of the time derivative of the fourth measured variable O is above the fourth threshold value SW4.

[0031] If the amount of the time derivative of the first measured variable K does not exceed the first threshold value SW1 or if the amount of the time derivative of the second measured variable M does not exceed the second threshold value SW2, the first recording step 101 is carried out again.

[0032] Optionally, the first detection step 101 can be carried out if, alternatively or additionally, the amount of the time derivative of the third measured variable N is not above the third threshold value SW3 or the amount of the time derivative of the fourth measured variable O is not above the fourth threshold value SW4.

[0033] After the first determination step 104, a third detection step 105 takes place, in which at least one further first measured variable K2 is detected, wherein in a second comparison step 106 it is compared whether the at least one further first measured variable K2 essentially corresponds to the starting measured variable K Start If this is the case, an end time t E Optionally, the end time t E be determined when a relative deviation of the amount between the at least one further first measured variable K2 and the start measured variable K Start is less than a fifth predetermined threshold value SW5, in particular less than 5%. In an alternative embodiment of the invention, it can be provided that the end time t E after a specified period of time after the start time t Sis determined. If the comparison in the second comparison step 106 is negative, the third detection step 105 is repeated.

[0034] After the second determination step 107, a third comparison step 108 takes place, in which it is compared whether the amount of a difference between the end time t E and the start time t S greater than a specified minimum time period t min Alternatively or additionally, it can be provided that in the third comparison step 108 a comparison is made as to whether the amount of a time period that has already elapsed since the starting time t S greater than a specified minimum time period t min Furthermore, alternatively or additionally, it can be provided that in the third comparison step 108 after a predetermined minimum time period t min it is compared whether the at least one further first measured value K2 is smaller than the starting measured value K Startis. If this is not the case, the measurement is terminated and a new measurement can optionally be carried out. However, if the comparison step 108 is positive, an output signal 10 is generated in a subsequent signal generation step 109, which can be converted into a signal tone, for example, by a loudspeaker. Optionally, it can be provided that a further output signal 11 is generated, which is converted into an optical signal, for example, by an LED. This acoustic or optical signal gives a user of the gas sensor 20 an indication that the ethanol concentration in the respiratory gas mixture, ie in his breath, is above a previously defined value.

[0035] Fig. Figure 4 shows graphical representations of the temporal progression of various measured variables. The upper diagram represents the temporal progression t of the measured variable M, representing the temperature of the respiratory gas. The middle diagram represents the temporal progression t of the measured variable N, representing the humidity of the respiratory gas. The lower diagram shows the temporal progression t of the measured variable K, representing the ethanol concentration of the respiratory gas.

[0036] At a time t1, an essentially simultaneous change in the temporal course of the measured variables M, N and K is detectable. This change is due to a user breathing into the gas sensor. To determine the exact starting time t Start to determine the change in the temporal courses of the measured variables M, N and K, ie in order to determine the start of the measurement, time derivatives Ṁ, Ṅ and K̇ of the recorded measured variables M, N and K are formed.

[0037] These time derivatives Ṁ, Ṅ and K̇ of the measured quantities M, N and K are shown graphically in the Fig. 5. It is clearly visible that for all three time derivatives Ṁ, Ṅ and K̇ of the measured quantities M, N and K, the change in the time courses occurs almost simultaneously. Thus, the determination of the starting time t Start The measurement can be significantly improved by including additional measured variables that represent further chemical and / or physical parameters of the breathing gas.

[0038] In Fig. Figure 6 shows a further graphical representation of a time course of a measurement of the measured variable K representing an ethanol concentration in a respiratory gas without prior alcohol consumption by a user. By forming the time derivative K̇ of the measured variable K and at least one further time derivative, for example, of the measured variable M representing the temperature of the respiratory gas, as can be seen from the Fig. 5, the starting time t Start of the measurement can be determined exactly. A value at this starting time t Start The measured value K is used as the corresponding starting measured value K Start stored in the memory unit 3. It can be seen that the measured quantity M is reduced to a minimum K E and then rises again. The minimum K Erepresents only a value of the measured variable K at a time when the user no longer breathes into the gas sensor and from which point onwards the sensor element 4, which senses the ethanol concentration in the respiratory gas mixture, regenerates. The sensor element 4 is fully generated when a further first measured variable K2 essentially corresponds to the initial measured variable K Start An end time t corresponding to the further first measured quantity K2 E is determined and stored in the memory unit 3. The time difference between t E and t Start is a measure of the ethanol concentration in the user's breathing gas.

[0039] For comparison, Fig. Figure 7 shows another graphical representation of the time course of a measurement of the measured variable K, representing the ethanol concentration in a breath gas, with previous alcohol consumption by a user using the same scale. It is clearly evident that the time difference between t E and t Start is greater than in the measurement without prior alcohol consumption by the user Fig. 6. Depending on a certain predetermined minimum time period t previously stored in the storage unit 3 min It can be provided that the gas sensor 20 issues a signal 10, 11 to the user to alert him that the ethanol concentration in his breath has reached a value determined by the minimum time period t min represented threshold.

Claims

[1] Method (100) for detecting a gaseous substance, in particular ethanol, in a gas mixture by means of a gas sensor, with • a first detection step (101), in which at least one first measured variable (K1) representing a first chemical and / or physical parameter of the gas mixture, in particular a concentration of ethanol, is detected by a first sensor element (4), • a second detection step (102), in which at least one second measurement variable (M) representing a second chemical and / or physical parameter of the gas mixture different from the first chemical and / or physical parameter, in particular a temperature, a pressure or a humidity, is detected by a second sensor element (5), • a first comparison step (103) in which a comparison is made as to whether an amount of a time derivative of the first measured variable (K1) exceeds a first predetermined threshold value (SW1) and whether an amount of a time derivative of the second measured variable (M) exceeds a second predetermined threshold value (SW2), • a first determination step (104), in which a start time (t S ) and one at the start time (t S ) corresponding starting measured value (K Start ) of the first chemical and / or physical parameter is determined if the first comparison (103) is positive, • a third detection step (105), in which at least one further first measured variable (K2) is detected, • a second comparison step (106), in which a comparison is made as to whether the at least one further first measured variable (K2) corresponds to the starting measured variable (K Start ) corresponds, • a second determination step (107), in which an end time (t E ) is determined if the second comparison (106) is positive, • a third comparison step (108), in which it is compared whether the amount of a difference between the end time (t E ) and the start time (t S ) is greater than a specified minimum period of time (t min ), and • a signal generation step (109) in which an output signal (10) is generated if the third comparison (108) is positive. [2] Method (100) according to claim 1, characterized by , that • in the second detection step (102), at least one third measurement variable (N) representing a chemical and / or physical parameter of the gas mixture different from the first and second chemical and / or physical parameters is additionally detected by a third sensor element (6), and • in the first comparison step (103) it is additionally compared whether an amount of a time derivative of the third measured variable (N) exceeds a third predetermined threshold value (SW3). [3] Method (100) according to claim 2, characterized by , that • in the second detection step (102), at least one fourth measurement variable (O) representing a chemical and / or physical parameter of the gas mixture different from the first, second and third chemical and / or physical parameters is additionally detected by a fourth sensor element (7), and • in the first comparison step (103) it is additionally compared whether an amount of a time derivative of the fourth measured variable (O) exceeds a fourth predetermined threshold value (SW4). [4] Method (100) according to one of the preceding claims, characterized by , that • the second comparison step (106) is positive if a relative deviation of the amount between the at least one further first measured variable (K2) and the starting measured variable (K Start ) is less than a fifth predetermined threshold (SW5), in particular less than 5%. [5] Control device (1) for carrying out a method (100) according to one of the preceding claims for detecting a gaseous substance, in particular ethanol, in a gas mixture by means of a gas sensor, with a computing unit (2) and a memory unit (3), wherein the computing unit (2) is set up, • in a first detection step (101), at least one first measured variable (K1) representing a first chemical and / or physical parameter of the gas mixture, in particular a concentration of ethanol, is detected by a first sensor element (4), • in a second detection step (102), at least one second measured variable (M) representing a second chemical and / or physical parameter of the gas mixture that is different from the first chemical and / or physical parameter, in particular a temperature, a pressure or a humidity, is detected by a second sensor element (5), • in a first comparison step (103), to compare whether an amount of a time derivative of the first measured variable (K1) exceeds a first predetermined threshold value (SW1) and whether an amount of a time derivative of the second measured variable (M) exceeds a second predetermined threshold value (SW2), • in a first determination step (104) a start time (t S ) and one at the start time (t S ) corresponding starting measured value (K Start ) of the first chemical and / or physical parameter if the first comparison (103) is positive, • in a third detection step (105) to detect at least one further first measured variable (K2), • in a second comparison step (106) to compare whether the at least one further first measured variable (K2) of the starting measured variable (K Start ) corresponds, • in a second determination step (107) an end time (t E ) if the second comparison (106) is positive, • in a third comparison step (108) to compare whether the amount of a difference between the end time (t E ) and the start time (t S ) is greater than a specified minimum period of time (t min ), and • to generate an output signal (10) in a signal generation step (109) if the third comparison (108) is positive. [6] Control device (1) according to claim 5, characterized by that the computing unit (2) is set up, • in the second detection step (102), additionally detecting at least one third measurement variable (N) representing a chemical and / or physical parameter of the gas mixture that is different from the first and second chemical and / or physical parameters by a third sensor element (6), and • in the first comparison step (103) to additionally compare whether an amount of a time derivative of the third measured variable (N) exceeds a third predetermined threshold value (SW3). [7] Control device (1) according to claim 6, characterized by that the computing unit (2) is set up, • in the second detection step (102), additionally detecting at least one fourth measurement variable (O) representing a chemical and / or physical parameter of the gas mixture different from the first, second and third chemical and / or physical parameters by a fourth sensor element (7), and • in the first comparison step (103) to additionally compare whether an amount of a time derivative of the fourth measured variable (O) exceeds a fourth predetermined threshold value (SW4). [8] Control device (1) according to one of claims 5 to 7, characterized by that the computing unit (2) is set up, • in the second comparison step (106) to determine a positive comparison if a relative deviation of the amount between the at least one further first measured variable (K2) and the starting measured variable (K Start ) is less than a fifth predetermined threshold (SW5), in particular less than 5%. [9] Gas sensor, in particular respiratory gas sensor, with a control device (1) according to one of claims 5 to 8, with a first sensor element (4) and a second sensor element (5).

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