Gas measurement device and gas measurement method

Abstract

The invention relates to a gas measuring device (100) and a gas measuring method, which are capable of measuring the concentration of a component in a gas mixture (A), in particular the concentration of respiratory alcohol in a respiratory sample. The gas mixture (A) flows into a tubular inlet unit (1) which is detachably connected to a base body (6, 16). A part of the gas mixture (A) is branched, and the gas sample (Gp) thus produced flows into the measuring chamber (2). A gas sensor (50) measures a measure for the concentration of a component in a gas sample (Gp). The gas sample (Gp) is branched off from the inlet unit (1) at an inlet point (P.e) and enters the inlet unit (1) again or into a channel to the environment at a downstream outlet point (P.a1). The measuring chamber (2) is connected to the two points (P.e, P.a1) by means of two different fluid-conducting units (3, 4).

Description

Technical Field

[0001] The present invention relates to a gas measuring device and a gas measuring method capable of measuring the concentration of a component in a gas mixture. Background Art

[0002] If a subject is to be examined with regard to whether the subject has been drinking alcohol, the task of measuring the concentration of a component in a gas mixture arises, for example. If the subject has been drinking alcohol, the air exhaled by the subject contains breath alcohol. In the case of this application, the gas mixture is a breath sample emitted by the subject, and the component is breath alcohol. The component can also be other substances that can be detected in a breath sample. Summary of the invention

[0003] The object of the present invention is to provide a gas measuring device and a gas measuring method which comprise a measuring chamber for receiving a gas sample and which are capable of conducting the gas sample towards and away from the measuring chamber with greater reliability than known devices and methods.

[0004] This object is achieved by a gas measuring device having the features of claim 1 and by a gas measuring method having the features of claim 11. Where appropriate, advantageous embodiments of the gas measuring device according to the invention are also advantageous embodiments of the gas measuring method according to the invention and vice versa.

[0005] The terms "fluid guiding unit" and "fluid transport unit" are used below. A fluid guiding unit is a component which can guide a fluid along a path predetermined by the geometry and the design and arrangement of the fluid guiding unit and which ideally prevents the guided fluid from leaving this path. Hoses and pipes are two examples of fluid guiding units. A fluid transport unit can, in particular, transport a fluid, i.e. move the fluid, through the fluid guiding unit. Pumps, blowers and piston-cylinder units are examples of fluid transport units.

[0006] The gas measuring device according to the invention and the gas measuring method according to the invention are capable of measuring the concentration of at least one component in a gas mixture. The gas mixture is for example the breathing air that has been emitted by the subject, and the component is breath alcohol or other substances that may be contained in the breath sample and should be detected. The gas mixture may also come from a source other than from the subject's mouth.

[0007] The gas measuring device according to the invention comprises a tubular input unit, wherein the input unit has an inlet opening and an outlet opening. The input unit preferably extends along a longitudinal axis. In addition, the gas measuring device comprises a substrate. The input unit is connected to the substrate or the input unit can be connected to the substrate, preferably detachably connected. The detachable connection makes it possible to replace the input unit after the gas sample is input and continue to use the substrate.

[0008] At least one measuring chamber of the gas measuring device and at least one gas sensor, optionally a plurality of gas sensors, in one embodiment a plurality of measuring chambers and a plurality of gas sensors are arranged in the interior of the base body. A design with a measuring chamber and a gas sensor is described below. This description also applies accordingly to a design with a plurality of gas sensors and / or a plurality of measuring chambers.

[0009] The measuring chamber can receive a gas sample. The base body has an inlet point and an outlet point, wherein the two points are spaced apart from each other. The feed fluid guiding unit connects the inlet point to the measuring chamber. The discharge fluid guiding unit connects the measuring chamber to the outlet point. The two fluid guiding units are arranged in the base body spaced apart from each other and without crossing. Preferably, the two fluid guiding units or at least the segments in the two fluid guiding units extend along two longitudinal axes, wherein the two longitudinal axes respectively enclose an angle of at least 60° with the longitudinal axis of the input unit, and particularly preferably, both are perpendicular to the longitudinal axis of the input unit.

[0010] The gas measuring method according to the present invention is performed using such a gas measuring device. The gas measuring device is designed to perform the following steps, and the gas measuring method includes the following steps:

[0011] The input unit is connected to the base body or the input unit is connected to the base body.

[0012] A gas mixture, for example a breath sample, flows through the inlet opening into the input unit.

[0013] - At the inlet point, the gas sample is branched off from the gas mixture flowing through. The remainder of the gas mixture, i.e. the gas mixture without the branched off gas sample, flows past the inlet point and then past the outflow point and then leaves the input unit through the outlet opening. Preferably, at most 10% by volume of the gas mixture is branched off as the gas sample.

[0014] The branched-off gas sample flows through the feed fluid guiding unit into the measuring chamber.

[0015] The branched-off gas sample flows out of the measuring chamber and through the outlet fluid conducting unit to the outflow point and there flows out of the base body.

[0016] According to a first alternative, the gas measuring device is designed as follows, and the gas measuring method comprises the following steps:

[0017] The branched-off gas sample flows back again into the input unit at the outflow point.

[0018] The entire gas mixture including the branched gas sample leaves the input cell through the outlet opening.

[0019] According to a second alternative, the gas measuring device is designed as follows, and the gas measuring method comprises the following steps:

[0020] At the outflow point, the branched-off gas sample flows out of the base body and, after flowing out of the base body, flows past the inlet unit and then into the environment of the gas measuring device.

[0021] While the branched gas sample flows past the input unit, it flows away from the inlet opening and preferably in a direction parallel to the longitudinal axis of the input unit and thus parallel to the remainder of the gas mixture, ie the unbranched part of the gas mixture.

[0022] In both alternatives, both the branched-off gas sample and also the remainder of the gas mixture preferably flow back into the environment of the gas measuring device.

[0023] The or each gas sensor is designed to measure the concentration of a component in the gas sample while the gas sample is in the measurement chamber. More precisely: the or each gas sensor is capable of measuring a parameter that is related to the concentration of the component. In the case of at least two gas sensors, the two gas sensors preferably measure two different parameters, both of which are related to the concentration of the component.

[0024] The terms "upstream" and "downstream" as well as "left" and "right" are used below. These terms relate to the direction in which the gas mixture flows through the input unit and have the usual meaning with respect to this direction. The terms "above" and "below" relate to the orientation in which the user holds the base body in his hand and the input unit is located above the base body. In the context of the present application, downstream means a direction away from the user.

[0025] According to the invention, the gas mixture flows into the tubular input unit through the inlet opening. At least that part of the gas mixture which does not branch off in the entry point leaves the input unit through the outlet opening. The branched part, i.e. the gas sample, leaves the base body through the outflow point. According to a first alternative, the branched part flows again into the input unit. According to a second alternative, the branched part flows past the input unit and in a direction away from the inlet opening of the input unit.

[0026] In many cases, the gas measuring device is held by a person, for example because this person or another person inputs the gas mixture into the input unit. The features just described in combination with the tubular shape of the input unit reduce the risk that the gas mixture is blown or flows towards the face of the person or otherwise unintentionally reaches the person after the gas mixture flows through the input unit. The base body can be aligned so that the outlet opening of the input unit is not pointed towards the person. Undesirable events of the gas mixture flowing towards the face of the person can be prevented without necessarily having a blocking element in the input unit.

[0027] The event that the outflowing gas mixture reaches a person is undesirable, that is, especially because the gas mixture may contain pathogens, which is especially possible when the gas mixture is exhaled breathing air. On the contrary, the gas mixture is led away from the gas measuring device in a defined manner.

[0028] Typically, the input cell comprises, in addition to the inlet opening and the outlet opening, further openings, wherein the further openings act as entry points, in which the gas sample is branched. The second alternative avoids the necessity of placing additional openings in the wall of the input cell in addition to the entry points, wherein the additional openings act as outflow points. In some cases, two openings in the wall of the input cell lead to more eddies and turbulence in the input cell than only one opening.

[0029] Typically, when the gas sample is branched from the input unit and flows through the feed fluid guiding unit, the branched gas sample changes its flow direction. This feature reduces the risk of substances harmful to the measurement chamber or to the gas sensor reaching the measurement chamber. In particular, the risk of water in the gas sample condensing on the surface of the measurement chamber or on the surface of the sensor or larger particles from the environment or the input unit reaching the measurement chamber is reduced. This risk would be greater if the gas mixture would flow from the inlet opening into the measurement chamber without a change of direction.

[0030] According to the present invention, the branched gas sample flows into the measuring chamber through the feed fluid guiding unit and flows out of the measuring chamber through the discharge fluid guiding unit. The present invention eliminates the necessity for the gas sample to first flow into the measuring chamber through the same fluid guiding unit and then flow out of the measuring chamber. Designs with a single fluid guiding unit or with two intersecting fluid guiding units may lead to backflow in the single fluid guiding unit or at the intersection. If the gas sample is sucked in by the piston, the piston passes through a relatively long stroke in many cases in the case of a single fluid guiding unit. The present invention makes it possible to branch the gas sample with the aid of a relatively small fluid delivery unit and then discharge the gas sample again from the measuring chamber. Continuous measurement that is theoretically unlimited in time can be achieved. When the piston is used in combination with a single fluid guiding unit, the measurement inevitably has to be interrupted frequently.

[0031] According to the invention, the gas sample flows from the measuring chamber through the exhaust fluid guiding unit to the outflow point and flows out of the exhaust fluid guiding unit at the outflow point. According to a first alternative, the gas sample flows again into the input unit at the outflow point so that the entire gas mixture flows out through the outlet opening of the input unit.

[0032] In the case of the second alternative, the branched gas sample and the remaining part of the gas mixture usually flow out into the environment at two locations spaced apart from one another. According to a design of the second alternative, the gas sample is mixed in a mixing region arranged downstream of the outlet opening of the input unit with the part of the gas mixture that flows through the input unit without being branched.

[0033] In one embodiment of the design, if the input unit is connected to the base body, a channel is formed between the input unit and the base body. The channel connects the outflow point to the mixing region. The mixing region belongs to the environment of the gas measuring device or is in fluid connection with the environment. The channel preferably extends parallel to the longitudinal axis of the tubular input unit. The gas sample flows from the measuring chamber through the exhaust fluid guide unit to the outflow point and then flows from the outflow point through the channel and thus flows past the input unit to the mixing region.

[0034] In some cases, the second alternative and in particular the design just described reduces the risk of undesired eddies in the input unit and / or backflows in the discharge fluid guide unit. The channel conducts the gas mixture away from the inlet opening of the input unit with particularly high reliability. This further reduces the risk of a portion of the gas mixture flowing toward the face of a person in front of whose face the input unit is located.

[0035] It is possible that the outlet opening of the input unit is flush with the base body. It is also possible that the input unit protrudes beyond the base body upstream and / or downstream. In a design, on the contrary, the base body protrudes beyond the input unit downstream of the input unit. Downstream of the outlet opening, a region is formed, which is formed on one side by the input unit, in particular by the outlet opening, and on the other side by the part of the base body that protrudes downstream. The entire gas mixture reaches this region, that is, in the case of the first alternative, through the outlet opening. In the case of the second alternative, the branched gas sample reaches this region through the outflow point and passes by the input unit, and the remaining part of the gas mixture arrives through the outlet opening. This design can be combined with the just-described implementation of the second alternative, in which the channel between the base body and the input unit leads to a mixing region.

[0036] In one embodiment, the separation element divides the input unit into an inlet-side chamber and an outlet-side chamber. The inlet opening is adjacent to the inlet-side chamber, and the outlet opening is adjacent to the outlet-side chamber. At least one through-flow opening is embedded in the separation element. Both the inlet point and the outflow point are adjacent to the outlet-side chamber. The separation element separates the outlet-side chamber from the inlet opening. The entire gas mixture passes through the inlet opening, through the inlet-side chamber, and flows to the separation element. At least a portion of the gas mixture flows through the through-flow opening in the separation element into the outlet-side chamber.

[0037] The gas sample is thus branched off from the input unit downstream of the separation element and in the outlet-side chamber. Compared to a design without a separation element in the input unit, this design reduces the risk of eddies or very large overpressures or underpressures in the outlet-side chamber relative to the ambient pressure. This makes it easier to branch off the gas sample with a relatively uniform volume flow.

[0038] The separation element can be designed as a purely passive mechanical component. In one embodiment, the inlet-side chamber extends along the entire length of the input unit, i.e. from the inlet opening to the outlet opening, and, viewed in the flow direction of the gas mixture through the input unit, a section of the inlet-side chamber is located next to or above the outlet-side chamber. This embodiment further reduces the risk of eddies or large negative pressures or negative pressures in the outlet-side chamber.

[0039] Preferably, the input unit can be detachably connected to the base body and separated from the base body again. In one design, the gas measuring device includes a pressure sensor. The pressure sensor is capable of measuring the pressure in the fluid guiding unit - more precisely: directly measuring the pressure or a parameter related to the pressure. In one implementation, the fluid guiding unit is a feed fluid guiding unit, and in another implementation it is a discharge fluid guiding unit. Based on the measured pressure, the gas measuring device - more precisely: a signal processing control device or other device of the gas measuring device - can automatically determine whether the input unit is connected to the base body. When the input unit is placed, the pressure is usually significantly greater than when the input unit is not placed, that is, it is above a predetermined pressure limit. This significant difference occurs at least during the flow of fluid through the fluid guiding unit, especially during the input of the gas mixture into the input unit or during the flushing of the measuring chamber.

[0040] This design reduces the risk that one of the following undesirable events could occur without being detected:

[0041] - Ambient air flows into or out of the measuring chamber via the fluid conducting unit with the pressure sensor. The measuring chamber is thus flushed after a measurement and can be used for a new measurement after the flushing. This flushing is a desired process. During the flushing, the input unit should not be connected to the base body so that the measuring chamber is actually completely flushed.

[0042] - Although the gas measuring device is now to be used for checking the composition of the gas mixture, the input unit is not connected to the base body. This is clearly an error.

[0043] When the gas measuring device has detected one of the two undesirable events, the gas measuring device preferably generates a message. The message is output in a form perceptible by a human, ie preferably by an output unit of the gas measuring device.

[0044] According to the invention, a portion of the gas mixture flowing through the input unit is branched off and conducted as a gas sample through the feed fluid guide unit into the measuring chamber. In one embodiment, the kinetic energy and / or potential energy of the gas mixture flowing into the input unit is sufficient to branch off the gas mixture. This applies, for example, when the gas mixture is a breath sample, which is emitted by the subject, provided that the subject exhales sufficiently strongly. It is possible that the gas measuring device does not include its own fluid transport unit.

[0045] And in one design, the gas measuring device includes a fluid delivery unit, such as a pump or a piston-cylinder unit or a blower. The fluid delivery unit can be turned on and off. The fluid delivery unit can at least deliver the gas sample out of the measurement chamber and deliver it through the exhaust fluid guiding unit. Usually, the gas then flows into the measurement chamber through the feed fluid guiding unit, especially because a negative pressure is generated in the measurement chamber. As a result, the measurement chamber is flushed, and a new gas sample is sucked into the measurement chamber. In one implementation, the fluid delivery unit further helps or even only causes: the gas sample is branched from the gas mixture flowing through the input unit. In the case of this implementation, the fluid delivery unit preferably sucks the gas sample into the measurement chamber through the feed fluid guiding unit.

[0046] The design with a fluid delivery unit can be combined with a design in which a pressure sensor measures a measure for the pressure in the fluid delivery unit. In this combination, the pressure sensor measures a measure for the pressure in the exhaust fluid guiding unit. Based on the measured pressure, i.e. based on the signal of the pressure sensor, the gas measuring device can automatically determine whether the fluid delivery unit is switched on or off. Usually, the fluid delivery unit should be switched on at least temporarily when a gas mixture is fed into the input unit.

[0047] The design just described can be combined with a design in which the input unit can be detachably connected to the base body and separated from the base body again. According to this combination, the gas measuring device can automatically distinguish the following three situations from each other:

[0048] - Fluid delivery unit switched off (low pressure).

[0049] The fluid delivery unit is switched on and the inlet unit is not connected to the base body (medium pressure).

[0050] The fluid delivery unit is switched on and the input unit is connected to the base body (high pressure).

[0051] In some cases, the gas measuring device can also detect the following undesirable situation: the fluid delivery unit is switched off, but a pressure between low pressure and medium pressure is present in the exhaust fluid guiding unit. This can be a sign that the subject is inputting a breath sample into the input unit despite the fluid delivery unit being switched off. This is usually undesirable.

[0052] In another embodiment, the gas measuring device uses the signal of the pressure sensor in order to measure a measure for the volume flow, which the fluid conveying unit realizes. The volume flow is the volume that flows through the fluid-conducting unit per unit time. For example, the knowledge of the volume flow can be used to control the fluid conveying unit with a control target, i.e. the actual and usually temporally variable volume flow follows a predefined time course, in particular is constant in time. The two embodiments can be combined with one another:

[0053] - using the signal of the pressure sensor for distinguishing three situations from one another with a detachable input unit and a fluid delivery unit that can be switched on and off, and

[0054] - Use this signal to measure a measure for the volume flow.

[0055] In other words: the signal of the pressure sensor can be used for the two different purposes just described.

[0056] In one embodiment, the fluid delivery unit just described includes the following components:

[0057] - a chamber whose volume can be changed,

[0058] - executive body,

[0059] -Suction check valve and

[0060] -Discharge check valve.

[0061] The actuator is capable of changing the volume of the chamber. For example, the chamber is defined by a diaphragm or other movable wall, and the actuator is mechanically connected to the movable wall.

[0062] The suction fluid guiding unit connects the chamber of the fluid delivery unit with the measuring chamber. The discharge fluid guiding unit connects the chamber with the discharge fluid guiding unit. Thus, the chamber is in suction fluid connection with the measuring chamber and in discharge fluid connection with the discharge fluid guiding unit. The suction check valve enables the flow of fluid through the suction fluid connection into the chamber and prohibits flow in the opposite direction. The discharge check valve enables the flow of fluid through the discharge fluid connection into the discharge fluid guiding unit and prohibits flow in the opposite direction.

[0063] In the case of this design, the fluid delivery unit can be used not only to branch off the gas sample from the gas mixture flowing through the input unit and deliver it to the measuring chamber, but also to discharge the gas sample from the measuring chamber and thereby flush the measuring chamber. In many cases, this design enables a fluid delivery unit that requires relatively little installation space and / or consumes relatively little electrical energy. In addition, in many cases, this arrangement prevents the gas from flowing through the measuring chamber in an undesirable manner in the opposite direction.

[0064] According to the invention, the gas sensor or each gas sensor of the gas measuring device is capable of measuring the fraction and / or concentration of a component of the gas sample in the measuring chamber. In one design, the gas sensor or the gas sensor is designed as a photoelectric sensor. The gas sensor comprises a radiation source and a photodetector. The radiation source is capable of emitting electromagnetic radiation. The emitted electromagnetic radiation penetrates the measuring chamber and impinges on the photodetector. The photodetector is capable of generating a signal according to the intensity of the impinged radiation and is therefore a photodetector. The generated signal comprises information about the concentration of a component of the gas sample in the measuring chamber.

[0065] Gas sensors designed in this way are able to continuously, i.e. at a high sampling frequency, provide a signal about the current concentration of a component. Furthermore, such sensors do not use chemical substances and, in many cases, are less sensitive than other gas sensors to substances that penetrate into the measuring chamber and to high temperatures that could lead to evaporation of chemical substances. Therefore, in many cases, it is not necessary to seal the measuring chamber in a fluid-tight manner with respect to the environment when the gas measuring device is not in use.

[0066] In a modification of the design, the gas measuring device further comprises an electrochemical sensor in addition to the photoelectric sensor. In an alternative, the gas measuring device is designed so that the branched gas samples reach the two sensors in sequence. Thus, the two sensors are connected in series. In another alternative, the gas measuring device is designed so that other gas samples are branched and the other gas samples reach the electrochemical sensor. Or the branched gas samples are distributed to the two sensors. Thus, the two sensors are connected in parallel.

[0067] The other gas sensor has an electrical detection parameter. During operation, a chemical reaction is carried out in the other gas sensor. The chemical reaction carried out affects the electrical detection parameter. The chemical reaction and therefore the electrical detection parameter depend on the concentration of the components in the gas sample or other gas samples. The electrochemical sensor is capable of measuring the electrical detection parameter. The electrochemical sensor is capable of generating a signal based on the measured electrical detection parameter. The generated signal includes information about the concentration of the components in the gas sample or other gas samples. In one implementation, the component being searched for in the gas mixture is an oxidizable component, and the chemical reaction corresponds to the chemical reaction that is carried out in the fuel cell and causes the flow of current.

[0068] The design with two gas sensors using different measuring principles provides redundancy. If a gas sensor fails, the gas measuring device can still be used in many cases. In addition, a plausibility check can be performed. If the two sensors provide significantly different measurement results for the same component of the gas sample, this is a sign that at least one gas sensor is defective or may be defective or the fluid guide unit is clogged. In addition, a gas measuring device with two sensors using different measuring principles can often reliably measure at least two different components in the same gas mixture.

[0069] In a preferred design, the gas measuring device according to the invention is capable of detecting the presence and / or concentration of alcohol in an input gas mixture. In this application, the gas mixture is a breath sample of a subject. In the case of this design, the gas sensor or each gas sensor is capable of measuring a measure for the concentration of breath alcohol in the breath sample, respectively. The gas measuring device is therefore an alcohol measuring device. In a design, the alcohol measuring device comprises the two sensors further described above, namely a photoelectric sensor and an electrochemical sensor.

[0070] The gas measuring device is preferably designed as a portable device. Particularly preferably, the input unit can be held in front of the mouth of the subject so that the inlet opening is directed toward the subject. The gas measuring device preferably comprises its own voltage supply unit in order to be independent of a fixed voltage supply network. The gas measuring device is preferably capable of outputting the result of the measurement on its own output unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The present invention is described below based on embodiments. In this case,

[0072] Figure 1 The alcohol measuring device is shown in right side view;

[0073] Figure 2 Show Figure 1 An alcohol measuring device, wherein the base body and the fluid delivery unit are omitted;

[0074] Figure 3 The alcohol measuring device is shown in left side view;

[0075] Figure 4 The alcohol measuring device is shown in a left oblique lower view;

[0076] Figure 5 A fragment from a cross-sectional illustration is shown;

[0077] Figure 6 The alcohol measuring device is shown in a left oblique rear view;

[0078] Figure 7 The mouthpiece and cover are shown from above;

[0079] Figure 8 The cover is shown from above with the mouthpiece removed;

[0080] Fig. 9 shows a cross section through a gas measuring device, wherein the viewing direction is obliquely to the rear;

[0081] Fig.10 A fluid conveying unit in the form of a diaphragm pump is schematically shown. DETAILED DESCRIPTION

[0082] In an embodiment, the invention is used to check whether the subject has been drinking. It is known that if the subject has previously drunk alcohol and alcohol is therefore in his blood, the air exhaled by the person contains alcohol. For example, the invention is used to check vehicle drivers or facility operators for breath alcohol.

[0083] Figures 1 to 9 The portable alcohol measuring device 100 or a detail of the use of the invention is shown from different viewing directions. A person, such as a police officer or the subject himself, holds the alcohol measuring device 100 in his hand. The subject (not shown) inputs a breath sample A into the tubular mouthpiece 1. The mouthpiece 1 serves as an input unit and extends along the longitudinal axis L.1 and tapers gradually. The emitted breath sample A passes through the inlet opening Into the mouthpiece 1. At least a portion of the breath sample A passes through the outlet opening Again from mouthpiece 1, where the outlet is open Smaller than the inlet opening The designations “left side”, “right side”, “upstream” and “downstream” used below relate to the flow direction of the breath sample A through the mouthpiece 1 .

[0084] In this embodiment, the inlet opening is circular, and the outlet opening Has a trapezoidal shape with rounded corners, see Figure 6 and Fig. 9 .

[0085] The mouthpiece 1 is detachably connected to an approximately square base body. The base body comprises a two-part housing, of which the cover 6 is shown in perspective and the base part 16 is shown only schematically. The mouthpiece 1 engages in the cover 6 and can be removed from the cover 6 again. A person holds the base part 16 in his hand and places the inlet opening 16 in the mouthpiece. The mouthpiece 1 is held in front of the subject's mouth so that the subject can enter the breath sample A into the mouthpiece 1. At least a portion of the breath sample A passes through the outlet opening. Flows out and reaches the environment again. It is possible that the remaining part of the breath sample A flows past the mouthpiece 1 and then flows out into the environment.

[0086] The mouthpiece 1 has the shape of a tube. Therefore, the base portion 16 and thus the mouthpiece 1 can be positioned and oriented so that the breath sample A flowing out of the mouthpiece 1 flows in a desired direction. Thus, the risk of the outflowing breath sample A flowing into the face of the subject or other people nearby is relatively low.

[0087] Figure 1 The alcohol measuring device 100 is shown in a right side view, ie the breath sample A flows through the mouthpiece 1 from left to right. Figure 2 Show Figure 1 An alcohol measuring device 100 in which the base bodies 6 and 16 are omitted. Figure 3 The alcohol measuring device 100 is shown in a left side view, ie the breath sample A flows through the mouthpiece 1 from right to left. Figure 4 The alcohol measuring device 100 is shown in a left oblique downward view, ie the breath sample A flows through the mouthpiece 1 from right to left. Figure 5 A fragment of a sectional illustration is shown, wherein the viewing direction is from the left. Figure 6 The alcohol measuring device 100 is shown in an oblique view to the right, ie the breath sample A flows obliquely towards the observer. Figure 7 The mouthpiece 1 and the cover 6 are shown from above, with the remaining components omitted. Figure 8 The cover 6 is shown from above, with the mouthpiece 1 additionally being omitted. Figure 7 and Figure 8 As can be seen in FIG. 1 , the cover 6 protrudes beyond the mouthpiece 1 downstream of the mouthpiece 1 by a section d, that is, at the outlet opening Outstanding. Fig. 9 A cross section through the alcohol measuring device 100 is shown obliquely from behind in the viewing direction, ie at the height of the tube 15 explained in greater detail below.

[0088] The separation element 24 divides the mouthpiece 1 into an inlet-side chamber Ke and an outlet-side chamber Ka, see Figure 5 The inlet side chamber Ke and the inlet opening Adjacent, the outlet side chamber Ka and the outlet opening The separation element 24 separates the two chambers Ke, Ka from each other in a fluid-tight manner, i.e. except for the opening When the subject emits a breath sample A, a dynamic pressure (Staudruck) occurs in the inlet-side chamber Ke. A pressure sensor (not shown) measures a measure for this dynamic pressure. The time course of this dynamic pressure indicates whether the subject inputs the breath sample A into the mouthpiece 1, and if so, when the subject inputs the breath sample A into the mouthpiece 1 and how long the subject inputs the breath sample A into the mouthpiece 1. Due to the separation element 24, a pressure that only slightly deviates from the ambient pressure occurs in the outlet-side chamber Ka.

[0089] exist Figure 5 In the implementation shown in FIG. 1 , the inlet side chamber Ke is connected to the inlet opening. Extends to the outlet opening In one implementation, the outlet side chamber Ka is connected to the outlet opening by a wall. In the flow direction of the breath sample A flowing through the input unit 1, the outlet chamber Ka is located between the inlet chamber Ke and the outlet opening. Next to the adjacent segment.

[0090] The projection 7 at the mouthpiece 1 engages with a corresponding groove 23 in the cover 6, see Figure 8 In the mouthpiece 1, two opposing grooves 20 are arranged at the outlet opening. When the mouthpiece 1 is inserted, the tabs 21 of the cover 6 engage with the grooves 20, see Figure 6 and Fig. 9 .

[0091] A portion of the breath sample A passes from the outlet-side chamber Ka of the mouthpiece 1 into the measuring colorimeter 2, which serves as a measuring chamber. This portion is referred to below as the "gas sample Gp". The measuring colorimeter 2 has an approximately cylindrical shape and extends along a longitudinal axis L.2, which in this embodiment is perpendicular or inclined to the longitudinal axis L.1 of the mouthpiece 1. When a person holds the base body 6, 16 in his hand, the longitudinal axis L.2 is arranged almost vertically. As in Figure 6 As can be best seen in FIG. 1 , the measuring cuvette 2 is slightly offset laterally to the right relative to the mouthpiece 1 and relative to the cover 6. The measuring cuvette 2 preferably has an inner wall that reflects electromagnetic radiation. The wall is made of a material that ideally does not chemically react with the gas sample, for example, gold or an alloy containing gold.

[0092] The measuring cuvette 2 is surrounded by a housing 13. The housing 13 is fastened to the inner wall of the base body 6, 16 by means of fastening elements 14. The housing 13 is omitted in many of the figures.

[0093] At least one gas sensor measures the content of breath alcohol in a gas sample Gp located in a measuring cuvette 2. Various principles of how a gas sensor can work can be applied, such as electrochemical sensors, infrared sensors, ionization sensors or photoacoustic sensors.

[0094] In this embodiment, the alcohol measuring device 100 comprises a photoelectric sensor 50. The sensor 50 comprises a measuring colorimeter 2, a radiation source 35, a photodetector 36 and optionally a wavelength filter (not shown). The radiation source 35 and the photodetector 36 are preferably arranged at two opposite end walls (Stirnwand) of the measuring colorimeter 2 in order to achieve a large optical path. In this embodiment, the radiation source 35 is arranged at the bottom and the photodetector 36 is arranged at the top.

[0095] The radiation source 35 emits electromagnetic radiation, in particular infrared radiation, into the measuring cuvette 2. The electromagnetic radiation penetrates the measuring cuvette 2 at least once and strikes the photodetector 36. The photodetector 36 generates an analog or digital signal depending on the intensity of the incident radiation. The breath alcohol in the measuring cuvette 2 absorbs part of the electromagnetic radiation in a predetermined wavelength range. The wavelength filter preferably only allows radiation in this wavelength range to pass. This reduces the risk of small water droplets in the gas sample Gp falsifying the measurement result.

[0096] The greater the concentration of breath alcohol, the more electromagnetic radiation is absorbed in the relevant wavelength range in the measuring colorimeter 2. The signal of the photodetector 36 is therefore a measure for the concentration of breath alcohol in the gas sample Gp. An evaluation unit of a signal processing control device (control unit) 60 evaluates the signal of the photodetector 36 and generates a signal containing information about the content of breath alcohol in the gas sample Gp. Preferably, an output unit (not shown) of the alcohol measuring device 100 outputs this information in at least one form perceptible by humans.

[0097] The gas sample Gp is ​​branched off from the breath sample A flowing through the mouthpiece 1 at the entry point Pe. Preferably, at most 10% by volume (Vol.%) of the breath sample A is branched off as a gas sample, particularly preferably at most 2% by volume. The gas sample Gp flows through the feed line 3 and the connection 39 into the measuring cuvette 2, flows through the measuring cuvette 2 and out of the measuring cuvette 2 again through the discharge line 4, and in a first alternative, flows again into the mouthpiece 1. In this embodiment, the feed line 3 is a rigid tube and is heated, for example, by a heating element in the wall of the tube 3 and / or in the connection 39. The discharge line 4 is a flexible hose.

[0098] Figures 1 to 6The path of the gas sample Gp is ​​illustrated with the aid of arrows. The gas sample Gp enters the feed line 3 at the entry point Pe and flows through the feed line 3, through the measuring cuvette 2 and the discharge line 4 until it reaches the outflow point Pa, see Figure 2 and Figure 4 Subsequently, the gas sample flows through the tube 15 in the cover 6 until the outflow point P.a1. In a first alternative, the gas sample Gp enters the mouthpiece 1 again at the outflow point P.a1, see Figure 2 and Fig. 9 . Fig. 9 A cross section through the gas measuring device 100 is shown at the height of the outflow point P.a1 , wherein the longitudinal axis L.1 of the mouthpiece 1 is approximately perpendicular to the drawing plane.

[0099] In the second alternative, the gas sample Gp does not flow again into the mouthpiece 1. Instead, the gas sample Gp flows from the outflow point P.a1 in the groove 25 between the mouthpiece 1 and the cover 6 toward the outlet opening. Therefore, the gas sample Gp flows past the mouthpiece 1 into the environment of the alcohol measuring device 100 .

[0100] In both alternatives, the outflow point P.a1 is arranged at a distance downstream of the entry point Pe.

[0101] In this embodiment, the alcohol measuring device 100 includes, in addition to the just described photoelectric sensor 50 with the measuring colorimeter 2, the radiation source 35 and the photodetector 36, an electrochemical sensor 38 which is only schematically shown. Other gas samples are introduced through the opening in the cover 6. It flows out of the mouthpiece 1 and reaches the measurement chamber (not shown) of the electrochemical sensor 38. In the measurement chamber, a chemical reaction occurs, which affects the electrical detection variable. The chemical reaction is preferably the same chemical reaction that also occurs in the fuel cell (Brennstoffstelle). The electrical detection variable is measured and is a measure of the concentration of breath alcohol in other gas samples.

[0102] The feature that the alcohol measuring device 100 includes both the photoelectric sensor 50 and the electrochemical sensor 38 has the following advantages in particular:

[0103] - Two sensors create redundancy. If one gas sensor 50 or 38 fails, the other gas sensor 38 or 50 can still measure the breath alcohol content in the breath sample A.

[0104] The measured values ​​of the two sensors 50, 38 can be compared with one another. If the measured values ​​deviate very strongly from one another, this can be a sign that at least one of the gas sensors 50, 38 is defective.

[0105] It is possible that breath alcohol, another component, is contained in the breath sample A and therefore in the gas sample Gp, to which the two gas sensors 50 and 38 react differently. In many cases, this other component can be reliably distinguished from breath alcohol when two different sensors 50 and 38 are used.

[0106] -The flow of gas flows through the measuring colorimeter 2 so that at each point in time there is a different gas sample Gp in the measuring colorimeter 2. The photoelectric sensor 50 measures the content of breath alcohol continuously, or more precisely: at a fixed sampling frequency. Therefore, the signal of the photoelectric sensor 50 provides the time course of the breath alcohol in the gas sample Gp. In many cases, this makes it possible to distinguish the contents of breath alcohol in different parts of the breath sample A from each other. The breath sample A includes a part from the mouth of the subject, followed by a part from the upper respiratory tract and finally a part from the lungs. The following knowledge is often desired: whether the measured value for the alcohol content involves a breath sample from the mouth, the upper respiratory tract or the lungs. The electrochemical sensor 38, based on its measurement principle, can only measure the content of breath alcohol at a lower sampling frequency than the photoelectric sensor 50.

[0107] The following description again refers to the gas sample Gp checked in the photoelectric sensor 50. Corresponding contents apply to other gas samples. The gas sample Gp is ​​mixed with the breath sample A from the inlet opening in the mixing area Vb. Flows through mouthpiece 1 to the outlet opening In the case of the first alternative, the mixing region Vb extends in the mouthpiece 1 from the outflow point P.a1 to the outlet opening. See also Figure 2 and Fig. 9 In the case of a second alternative, the mixing zone Vb is arranged downstream of the mouthpiece 1 and above the channel 22, see Figure 5 and Figure 7 .

[0108] The second alternative has the following advantages in particular: in the case of the second alternative, the mixing region Vb in which the gas sample Gp mixes with the rest of the breath sample A is located downstream of the mouthpiece 1 and therefore outside the mouthpiece 1. The risk of eddies and / or backflows occurring in the outlet-side chamber Ka of the mouthpiece 1 is thus reduced.

[0109] A plurality of openings are embedded in the cover 6, among which there are

[0110] an opening for the access point Pe, in which the feed line 3 leading to the photoelectric sensor 50 begins,

[0111] - Opening where the non-guided feed line to the electrochemical sensor 38 begins, and

[0112] - in the case of a first alternative, an opening for the outflow point P.a1 into which the pipe 15 opens, see Figure 8 and Fig. 9 .

[0113] Furthermore, a plurality of holes L.6 are embedded in the cover 6 for screw connection with the base part 16, see Figure 5 and Figure 8 .

[0114] The channel 22 is embedded in the cover 6, see Figure 7 and Figure 8 The channel 22 extends along the entire longitudinal axis L.6 of the cover 6. If the mouthpiece 1 is placed on the cover 6, the mouthpiece 1 engages with the channel 22 and closes the plurality of openings in the cover 6, see Figure 5 Two openings for the entry point Pe and the outflow point P.a1 (first alternative only) and the opening Not closed.

[0115] It is possible that the overpressure generated by the subject in the mouthpiece 1 by exhaling is sufficient to guide the gas sample into the measuring colorimeter 2. In this embodiment, the fluid delivery unit 8 is preferably used to branch the gas sample Gp from the breath sample A flowing through the mouthpiece 1, deliver it to the measuring colorimeter 2 and discharge it again from the measuring colorimeter 2. The fluid delivery unit 8 inhales gas from the measuring colorimeter 2 through the pipeline 9. A negative pressure is thereby generated, and the gas sample Gp flows into the measuring colorimeter 2 through the feed line 3. In many cases, the gas sample Gp fills the measuring colorimeter 2 relatively uniformly, which improves the reliability of the measurement. The inhaled gas sample Gp flows from the measuring colorimeter 2 through the hose 9 and the rigid pipeline 10 into the chamber of the fluid delivery unit 8. The gas sample Gp then flows from the chamber of the fluid delivery unit 8 through the tube 12 into the exhaust line 4.

[0116] Various designs of the fluid delivery unit 8 are possible. In this embodiment, the fluid delivery unit 8 comprises a diaphragm pump 40, which is Fig.10 . The diaphragm pump 40 comprises a chamber 17 with a variable volume and a schematically shown actuator 28, which is able to change the volume of the chamber 17. In this schematic diagram, the feeds 9, 10 lead into the chamber 17 from the left, and the discharge 12 leads out of the chamber 17 on the right. The suction check valve 31 releases the flow of gas into the chamber 17 and blocks the flow in the opposite direction. Correspondingly, the discharge check valve 32 releases the flow of gas out of the chamber 17 and blocks the flow in the opposite direction.

[0117] In this exemplary embodiment, the volume flow of the gas sample GP through the measuring cuvette 2 is measured. By integrating upwards in time, the control device 60 approximately derives from the measured volume flow the volume that has flowed into the measuring cuvette 2 since a certain event, for example since the placement of the mouthpiece 1. The measurement result of the alcohol measuring device 100 is only valid if the gas sample Gp reaches the measuring cuvette 2 in a sufficiently large volume.

[0118] The "volume flow", also referred to as the volume flow, is understood to be the volume per unit time of the fluid flowing through the fluid conducting unit, for example through the measuring cuvette 2. To measure the volume flow, a temporally variable pressure difference is measured with a specific sampling frequency, i.e. the difference between the pressure at the point Se where the fluid flows out of the feed line 3 and enters the measuring cuvette 2 and the pressure at the point Sa where the fluid flows out of the measuring cuvette 2 and enters the line 9, see Figure 3 This pressure difference is a measure for the volume flow. An implementation for measuring this pressure difference is described below.

[0119] The measuring line 5 is in fluid connection with the outlet opening of the feed line 3. Therefore, the same pressure exists in the measuring line 5 as at the position Se where the fluid enters the measuring colorimeter 2. The same pressure exists in the line 9 as at the position Sa where the liquid flows out of the measuring colorimeter 2. The sensor for the pressure difference is in fluid connection with the lines 9 and 5. The measured values ​​related to the pressure difference are transmitted to the control device 60, and the control device 60 derives the volume flow from these measured values ​​and generates a signal including the measured volume flow. The line 11 pneumatically connects the measuring line 5 to the line 10.

[0120] After the subject's breath sample A has been examined, it is necessary to flush the measuring cuvette 2. In this embodiment, a fluid delivery unit 8 is also used for flushing the measuring cuvette 2. During flushing, ambient air flows through the measuring cuvette 2 on the same path as the gas sample Gp to be examined. The measuring cuvette 2 can be cleaned with or without a connected mouthpiece 1. It is preferred to measure the volume flow even during flushing in order to ensure that a sufficient amount of ambient air flows through the measuring cuvette 2 during flushing.

[0121] It is also possible that the fluid delivery unit 8 is used only for flushing the measuring cuvette 2. As already explained, in one design, the pressure of the breath sample A emitted by the subject is sufficient so that the gas sample Gp to be examined reaches the measuring cuvette 2. The design of using the fluid delivery unit 8 only for flushing the measuring cuvette 2 makes it possible to use a fluid delivery unit that occupies less installation space and consumes less electrical energy than a fluid delivery unit for inhaling the breath sample A.

[0122] Only when the mouthpiece 1 is correctly placed on the cover 6 and engaged, can the breath alcohol content be correctly measured. The mouthpiece 1 is then engaged with the channel 22. Preferably, the fluid delivery unit 8 should be switched on not only when the gas sample Gp is ​​branched off from the breath sample A, but also when the measuring colorimeter 2 is cleaned. The design described below enables automatic checking whether these preconditions are currently met.

[0123] A smaller pressure limit value x and a larger pressure limit value y are predefined. The pressure sensor 27 can measure a measure for the pressure in the discharge line 4. The pressure sensor 27 can belong to the above-mentioned sensors for pressure differences, wherein the pressure difference is measured in order to measure the volume flow into and out of the measuring colorimeter 2. The pressure sensor 27 is pneumatically connected to the discharge line 4 via a connecting line 29.

[0124] The control device 60 compares the measured pressure with two pressure limit values ​​x and y. If the measured pressure is less than the smaller pressure limit value x, the fluid delivery unit 8 is turned off. If the measured pressure is between the two pressure limit values ​​x and y, the fluid delivery unit 8 is turned on and the mouthpiece 1 is not placed on the cover 6. Or the mouthpiece 1 is not placed correctly, for example, not engaged, so that an excessive distance occurs between the mouthpiece 1 and the cover 6. If the measured pressure is greater than the larger pressure limit value y, the fluid delivery unit 8 is turned on and the mouthpiece 1 is placed. The reason for this distinction is that in the case of the placed mouthpiece 1, a greater pressure occurs in the discharge line 4 than in the absence of the mouthpiece 1. The pressure limit values ​​x and y are preferably determined empirically in advance.

[0125] If the alcohol measuring device 100 is supposed to receive and check a breath sample A, but the mouthpiece 1 is not placed at all or is not placed correctly, the alcohol measuring device 100 preferably outputs a message in a form perceptible by a human.

[0126] Reference numerals list

[0127]

[0128]

[0129]

Claims

1. A gas measuring device (100) for measuring the concentration of a component in a gas mixture (A), The gas measuring device (100) comprises - a tubular input unit (1), - a base body (6, 16), - a feed fluid guiding unit (3, 39), - a measuring chamber (2), - a discharge fluid guiding unit (4, 15), and - at least one gas sensor (50, 38), The input unit (1) - With inlet opening and outlet opening and - connected or connectable to the base body (6, 16), The measuring chamber (2) is arranged inside a base body (6, 16), The feed fluid guiding unit (3, 39) connects an inlet point (Pe) in the base body (6, 16) to the measuring chamber (2), and the discharge fluid guiding unit (4, 15) connects the measuring chamber (2) to an outlet point (P.a1) in the base body (6, 16), wherein the two fluid guiding units (3, 39, 4; 15) are spaced apart from each other, The gas measuring device (100) is designed such that: - a gas mixture (A) flows into the input unit (1) through the inlet opening (ō.e) and flows through the input unit (1), - a gas sample (Gp) is branched off from the flowing gas mixture (A) at the entry point (Pe), the remainder of the gas mixture (A), ie the gas mixture (A) of the unbranched gas sample (Gp), flows past the entry point (Pe), The gas measuring device (100) is further designed such that the branched gas sample (Gp) - flows from the entry point (Pe) through the feed guide (3, 39) into the measuring chamber (2) and - flows from the measuring chamber (2) through the discharge fluid guiding unit (4) to the outflow point (P.a1), and The gas measuring device (100) is furthermore designed such that: In a first alternative, the branched gas sample (Gp) flows again into the input unit (1) in the outflow point (P.a1), and the entire gas mixture (A) passes through the outlet opening leaving the input unit (1), and In a second alternative, the branched gas sample (Gp) flows out of the substrate (6, 16) in the outflow point (P.a1) and flows away from the inlet opening flows past the input unit (1) in a direction of The or each gas sensor (50, 38) is designed to measure the concentration of a component in a gas sample (Gp) in the measurement chamber (2).

2. The gas measuring device (100) according to claim 1, characterized in that The gas measuring device (100) is designed such that, if the input unit (1) is connected to the base body (6, 16), a channel (25) is formed between the base body (6, 16) and the input unit (1). wherein the channel (25) connects the outflow point (P.a1) to the environment of the gas measuring device (100), wherein the channel (25) preferably extends along the longitudinal axis (L.1) of the input unit (1), and The gas measurement device (100) is designed so that the gas sample (Gp) flows from an outflow point (P.a1) through the channel (25).

3. The gas measuring device (100) according to any one of the preceding claims, characterized in that The base body (6, 16) - viewed in the flow direction of the gas mixture (A) through the inlet unit (1) - protrudes beyond the inlet unit (1) downstream of the inlet unit (1), Make the outlet opening The downstream of the input unit (1) constitutes a region (Vb) which is delimited on one side by the input unit (1) and on the other side by the base body (6, 16).

4. The gas measuring device (100) according to any one of the preceding claims, characterized in that The separation element (24) divides the input unit (1) into an inlet side chamber (Ke) and an outlet side chamber (Ka), wherein the inlet opening Adjacent to the inlet side chamber (Ke), wherein the outlet opening Adjacent to the outlet side chamber (Ka), At least one of the through-flow openings The two chambers (Ke, Ka) are connected to each other, and In this case, both the inlet point (Pe) and the outlet point (P.a1) are adjacent to the outlet-side chamber (Ka).

5. The gas measuring device (100) according to claim 4, characterized in that The inlet side chamber (Ke) has an inlet opening With outlet opening Connect, and Viewed in the flow direction of the gas mixture (A) through the feed unit (1), the section of the inlet-side chamber (Ke) is located next to the outlet-side chamber (Ka).

6. The gas measuring device (100) according to any one of the preceding claims, characterized in that The input unit (1) is detachably connected or connectable to the base body (6, 16), and The gas measuring device (100) comprises a pressure sensor (27), wherein the pressure sensor (27) is designed to measure the pressure in the feed fluid guiding unit (3, 39) or the pressure in the discharge fluid guiding unit (4, 15), and The gas measuring device (100) is designed to automatically determine whether the input unit (1) is connected to the base body (6, 16) based on the measured pressure.

7. The gas measuring device (100) according to any one of the preceding claims, characterized in that The gas measuring device (100) comprises a pressure sensor (27) and a fluid delivery unit (8), The fluid delivery unit (8) can be switched on and off. The connected fluid conveying unit (8) is designed to convey the gas sample (Gp) out of the measuring chamber (2) and through the discharge fluid guiding unit (4, 15), and wherein the pressure sensor (27) is designed to measure the pressure in the exhaust fluid guiding unit (4, 15), and The gas measuring device (100) is additionally designed to measure the pressure - determine whether the fluid delivery unit (8) is switched on or off, and / or - Measuring the volume flow achieved by the fluid delivery unit (8).

8. The gas measuring device (100) according to any one of the preceding claims, characterized in that The gas measuring device (100) comprises a fluid delivery unit (8), The fluid delivery unit (8) comprises - a chamber (17) with a variable volume, - an actuator (28), - Suction check valve (31) and - discharge check valve (32), wherein the actuator (28) is designed to change the volume of the chamber (17), wherein the chamber (17) is in an intake fluid connection (9, 10) with the measuring chamber (2) and in an exhaust fluid connection (12) with the exhaust fluid guiding unit (4, 15), The suction check valve (31) is designed to - enabling a flow of fluid through the suction fluid connection (9, 10) into the chamber (17), - prohibition of flow in the opposite direction, and The discharge check valve (32) is designed to - enabling a flow of fluid from the chamber (17) to the discharge fluid connection (12), and - Flow in the opposite direction is prohibited.

9. The gas measuring device (100) according to any one of the preceding claims, characterized in that The gas sensor or gas sensor (50) comprises a radiation source (35) and a photodetector (36), wherein the radiation source (35) is designed to emit electromagnetic radiation, wherein the gas measuring device (100) is designed such that the emitted radiation passes through the measuring chamber (2) and impinges on the photodetector (36), and The photodetector (36) is designed to A signal is generated as a function of the intensity of the incident radiation, such that the generated signal comprises information about the concentration of a component of the gas sample (Gp).

10. The gas measuring device (100) according to claim 9, characterized in that The gas measuring device (100) comprises a further gas sensor (38) having an electrical detection parameter, wherein the gas measuring device (100) - in an alternative embodiment, is designed such that the branched gas sample (Gp) reaches not only the gas sensor (50) having the radiation source (35) but also the further gas sensor (38), and - in a further alternative, is designed such that a further gas sample is branched off from the gas mixture (A) flowing through and reaches the further gas sensor (38), wherein the further gas sensor (38) is designed such that a chemical reaction takes place in the further gas sensor (38) and the reaction influences the electrical detection variable, wherein the chemical reaction and thus the electrical detection parameter depends on the concentration of a component in the gas sample (Gp) or in another gas sample, and The other gas sensor (38) is designed for - measuring said electrical detection parameter, and - generating a signal based on the measured electrical detection variable, such that the generated signal comprises information about the concentration of a component in the gas sample (Gp) or in other gas samples.

11. A method for measuring the concentration of a component in a gas mixture (A) using a gas measuring device (100), The gas measuring device (100) comprises - a tubular input unit (1), - a base body (6, 16), - a feed fluid guiding unit (3, 39), - a measuring chamber (2), - a discharge fluid guiding unit (4, 15), and - at least one gas sensor (50), The input unit (1) - With inlet opening and outlet opening and - at least temporarily connected to the base body (6, 16), The measuring chamber (2) is arranged inside a base body (6, 16), wherein two fluid guiding units (3, 39, 4; 15) are arranged in the base body (6, 16) at a distance from each other, The gas measurement method comprises the steps of: - Gas mixture (A) passes through the inlet opening flows into the input unit (1) and flows through the input unit (1), - a gas sample (Gp) is branched off from the gas mixture (A) flowing through in the matrix (6, 16) at the entry point (Pe), the remainder of the gas mixture (A), ie the gas mixture (A) of the unbranched gas sample (Gp), flows past the entry point (Pe), The gas measurement method comprises the following additional steps: In a first alternative, the branched gas sample (Gp) flows again into the input unit (1) in the matrix (6, 16) at the outflow point (P.a1), and the entire gas mixture (A) flows out through the outlet opening leaving the input unit (1), and In a second alternative, the branched gas sample (Gp) flows out of the substrate (6, 16) in the outflow point (P.a1) and flows away from the inlet opening flows past the input unit (1) in a direction of The gas measurement method comprises the following additional steps: - the branched gas sample (Gp) flows from the entry point (Pe) through the feed guide (3, 39) into the measurement chamber (2), - the or each gas sensor (50) measures the concentration of a component in the gas sample (Gp) in the measurement chamber (2), respectively, and - The gas sample (Gp) flows from the measurement chamber (2) through the discharge fluid guiding unit (4) to the outflow point (P.a1).

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