Analyzing device for concentration measurement, comprising valve and filter

Abstract

The invention relates to an analysis device (100) which is designed to inspect a gas mixture for a predetermined substance. A tubular input unit (70) can be connected to the base body. The gas mixture may be input into the input unit and flow from the inlet to the outlet. A fluid guide unit (71) connects a suction opening (AO) in the inlet unit (70) to the measuring chamber (3). The suction unit (5) is able to suck a gas sample (Gp) from an input unit (70) and to feed the gas sample through a fluid guide unit (71) into the measurement chamber (3). The sensor is capable of measuring the concentration of a substance in a gas sample (Gp) in the measurement chamber (3). The valve optionally releases or blocks the fluid directing unit (71). An electrostatically charged and / or mechanically active filter (23) in the fluid guide unit (71) is located between the suction opening (AO) and the valve.

Description

TECHNICAL FIELD

[0001] The invention relates to an analysis device which is capable of analyzing a gas mixture with respect to a preset substance and in which the concentration of the substance in the gas mixture can be measured. BACKGROUND

[0002] In one application, the gas mixture is a breath sample exhaled by a subject and the substance is breath alcohol or another substance which can be detected in the breath sample of the subject. In this application, it should be checked whether the subject has consumed alcohol or another substance and therefore whether the substance is present in his body. SUMMARY

[0003] It is the task of the invention to provide an analysis device which is capable of measuring the concentration of a substance in a gas mixture and which has a higher reliability than known analysis devices even in the case of long-term use.

[0004] This task is solved by an analysis device having the features of claim 1. Advantageous design solutions are given in the dependent claims.

[0005] The analysis device according to the invention is capable of analyzing a gas mixture with respect to a preset substance, in particular a breath sample with respect to breath alcohol.

[0006] The analysis device comprises a base body and an input unit. The input unit is connected or can be connected to the base body. In a first implementation, the input unit is fixedly connected to the base body. In a second implementation, the input unit comprises a mouthpiece and a tube, wherein the mouthpiece is detachably connected to the tube and the tube is fixedly connected to the base body. In a third implementation, the entire input unit is detachably connected to the base body, that is, can be separated from the base body again as a whole. In many cases, the second and third implementations facilitate better compliance with hygiene requirements.

[0007] The input unit has the shape of a tube, in particular the shape of a cylinder or truncated cone or prism with an n-sided cross section, wherein n >= 3. The input unit has an inlet, an outlet and a peripheral surface. The peripheral surface extends between the inlet and the outlet. In one design, the input unit tapers from the inlet to the outlet. The gas mixture to be analyzed can be input into the input unit through the inlet. The input gas mixture flows through the input unit in the direction of the outlet. The input gas mixture or at least the not extracted part of the gas mixture flows out of the input unit again through the outlet.

[0008] In the interior of the base body, there is a sensor assembly. The sensor assembly comprises a measuring chamber and a sensor. The measuring chamber is capable of receiving the gas sample to be checked.

[0009] An intake opening exists on the circumferential surface of the input unit. This intake opening is spaced from both the inlet and outlet. A fluid guiding unit connects the opening in the substrate to the measurement chamber. Therefore, when the input unit is connected to the substrate, the following condition is established: the fluid guiding unit connects the intake opening in the input unit to the measurement chamber. Gas samples can flow from the input unit through this fluid guiding unit into the measurement chamber. The fluid guiding unit is located inside the substrate. When the input unit is not connected to the substrate, the fluid guiding unit connects the opening in the substrate to the measurement chamber.

[0010] Note: A "fluid guiding unit" refers to a component that guides fluid—in this case, a gas sample—along a predetermined path through the component's structure and arrangement. Tubes and hoses are two examples of fluid guiding units.

[0011] The intake unit inside the matrix is ​​capable of performing the following steps: The intake unit draws in a gas sample from the gas mixture flowing through the input unit, meaning the gas sample branches off from the gas mixture. The gas sample is therefore a portion of the gas mixture flowing through the input unit. The remaining portion of the gas mixture is not extracted but remains in the input unit and flows out through the outlet. The intake unit delivers the gas sample through the intake opening and the fluid guide unit into the measurement chamber. Preferably, the intake unit is also capable of flushing the measurement chamber.

[0012] The sensor assembly's sensor is capable of measuring the concentration (proportion) and / or amount (e.g., mass) of a target substance in a gas sample when the gas sample is in the measurement chamber. Typically, the sensor measures a detection parameter related to the concentration and / or amount of the substance in the gas sample. The sensor assembly's signal processing and evaluation unit applies a preset functional relationship to the measured detection parameter (more precisely, to at least one measured value of the detection parameter) and thereby derives the concentration and / or amount of the substance in the gas sample. Optionally, the functional relationship depends on multiple measured parameters.

[0013] Note: The phrase "using a sensor to measure a physical parameter, such as the concentration of a substance in a gas sample" implies that the sensor can directly measure the physical parameter or at least one other parameter related to the parameter to be measured. The parameter, or the measured other parameter, or a combination of measured other parameters, thus serves as a scale for the physical parameter to be measured. The measurement provides at least one numerical value for the physical parameter being sought.

[0014] The preferred analytical device includes its own output unit. The analytical device displays the measured substance concentration on this output unit in a visual and / or other human-perceptible manner. If the substance concentration is outside a preset numerical range, the analytical device may optionally output an alarm on the output unit.

[0015] The valve, located inside the matrix, can be moved to both a closed end position and a released end position. In the closed end position, the valve closes the fluid guide unit, thus establishing no fluid connection between the measurement chamber on one side and the suction opening in the input unit or the opening in the matrix on the other side, and consequently, the surrounding environment of the analytical device. In the released end position, the valve releases the fluid guide unit, allowing the gas sample to flow from the input unit through the fluid guide unit into the measurement chamber. Ideally, in the closed end position, the valve completely fluid-tightly separates the measurement chamber from the surrounding environment and the input unit.

[0016] A filter is arranged within the fluid guiding unit. The filter is located between the aforementioned opening in the substrate and the measuring chamber. If the input unit is connected to the substrate, the filter is located between the suction opening and the valve. The filter is capable of filtering particles from a gas sample that flows through the fluid guiding unit and thus through the filter toward the measuring chamber. The phrase "particles are filtered out" means that the gas sample has or could have particles upstream of the filter, but ideally no longer has particles downstream of the filter due to the filter. The filter is particularly capable of mechanical action and / or being electrostatically charged, thereby attracting and binding particles.

[0017] Note: Typically, a filter consists of a real filter element and a support for the filter element. A gas sample flows through the filter element. The phrase "the filter functions mechanically and / or is electrostatically charged" implies that the filter element possesses these characteristics.

[0018] According to the invention, the gas mixture to be analyzed can be input into the input unit through the inlet, and the input gas mixture flows through the input unit towards the outlet. The portion of the gas mixture that does not branch out as a gas sample and is drawn into the measuring chamber flows out through the outlet into the surrounding environment. This feature is particularly advantageous if a subject inputs the gas mixture into the input unit. The risk of the gas mixture input by the subject flowing into the face of a person holding the analytical device is reduced; this person could be the subject themselves or another person holding the analytical device. Instead, the input unit can be positioned such that the gas mixture flows in the desired direction. There is no need to include obstructing elements in the input unit and / or change the flow direction of the gas mixture through the input unit.

[0019] The suction unit draws a gas sample from the gas mixture flowing through the input unit. This suction can be controlled in time by manipulating the suction unit accordingly. This allows the desired fraction to be drawn from the gas mixture. In particular, it allows the suction of a specific amount and / or a specific portion of the gas mixture, and more precisely, this is relatively independent of the volume, pressure, or flow rate of the gas mixture input into the input unit. Furthermore, suction can be performed within a specific time period during the input of the gas mixture into the input unit.

[0020] If the input gas mixture is a breath sample from the subject, the valve, in many cases, allows the aspirated gas sample to contain exhaled air from at least one region of the subject's respiratory system, but not exhaled air from at least one other region of the respiratory system. For example, it allows the gas sample to contain exhaled air from the upper respiratory tract and / or from the lungs, but not from the oral cavity. This feature facilitates reliable measurement of the breath alcohol content in a breath sample and, in particular, facilitates the determination of the presence of alcohol in the subject's blood.

[0021] According to the invention, the valve can fluid-tightly seal the fluid guiding unit at the closed end position and thus fluid-tightly separate the measurement chamber from the surrounding environment. This reduces the risk of evaporation of sensor components. This risk is particularly significant if the sensor is electrochemical. The risk of evaporation would be especially present without the valve if the analytical device is stored for extended periods and the measurement chamber is thus continuously fluidly connected to the surrounding environment via the fluid guiding unit. Furthermore, the sealed valve reduces the risk of particles and interfering substances, particularly interfering gases, entering the measurement chamber from the outside through the fluid guiding unit. Such particles and substances could cause functional malfunctions in the analytical device.

[0022] The use of valves, combined with detachable input units, offers the following advantages: valves eliminate the need for a closure to shut off the fluid guiding unit. Such a closure must be removed before the input unit is connected to the base. If the input unit is permanently connected to the base, the closure must be fitted onto both the inlet and outlet and removed before use. This is cumbersome. Removing the closure typically requires user intervention.

[0023] According to the invention, the filter is located in the fluid guiding unit and therein between the intake opening and the valve. If the valve is in the final or intermediate position of release and the gas sample is drawn in through the fluid guiding unit, this filter specifically causes the following result: the drawn-in gas sample flows first through the filter and then through the valve, more precisely, through the filter element. Ideally, the filter removes all particles with specific characteristics from the gas sample, such as particles larger than a predetermined upper limit, and in practice, at least at least a large proportion of these particles. The design of the filter determines which particles are to be filtered out. In the case of an electrostatically charged filter, particles with such predetermined characteristics are deposited on the filter, i.e., for example, all sufficiently large particles. "All particles" is an ideal design, which in practice can mostly only be approximated.

[0024] By filtering out particles with specific properties, the risk of undesirable events such as particles flowing with the gas sample to the valve and becoming lodged on the valve body and / or valve seat or other valve components, or flowing through the valve and into the measuring chamber, is reduced. Particles on the valve body or valve seat may cause the valve to not completely fluid-tightly seal the fluid guide unit, even in the closed end position. Subsequently, the following risks exist: the measuring chamber remains permanently fluidly connected to the surrounding environment, that is, even when the valve is in the closed end position. Particles in the measuring chamber may lead to erroneous analytical results.

[0025] According to the invention, the filter is located in the fluid connection between the inlet and the measuring chamber. This feature allows the advantages of a filter to be achieved without the need for a filter in the input unit. All the input gas mixture flows through the input unit, with only a branch of the gas mixture flowing through the fluid guiding unit. Therefore, more gas, preferably at least twice as much, particularly preferably at least five times as much, and particularly at least ten times as much, flows through the input unit compared to the fluid guiding unit. Consequently, the filter in the input unit is more susceptible to particulate contamination and experiences a greater mechanical load than the filter according to the invention in the fluid guiding unit. Furthermore, the filter in the input unit necessarily imposes aerodynamic resistance on the flowing gas mixture, and the gas mixture must be input at a greater pressure. For example, the subject must blow more forcefully into the input unit. Moreover, in many cases, the filter in the input unit increases the aerodynamic resistance of the input unit compared to an input unit without a filter, which may lead to undesirable backflow of the gas mixture within the input unit. This, in turn, may cause a portion of the gas mixture to flow towards the subject's face. This is undesirable.

[0026] In one design, the filter is electrostatically charged, thereby separating particles as the inhaled gas sample flows through the fluid guiding unit. The particles flow past at least one charged electrode, preferably multiple charged electrodes, and are thereby ionized. The electric field attracts the ionized particles to a current collector with the opposite charge, and they accumulate on the current collector. In one implementation of the electrostatically charged filter, the filter comprises a nonwoven fabric. The gas sample flows through the nonwoven fabric. Meltblown nonwoven fabric is particularly preferred as the nonwoven fabric.

[0027] In one design, the filter functions mechanically. The filter is able to remove particles from a gas sample, ideally removing all particles when these particles are larger than an upper limit predetermined by the filter's structure. In another implementation, the mechanical filter functions like a sieve (surface filter).

[0028] In another implementation, the filter comprises multiple (at least two, or at least three in one design) layers and / or is constructed as a porous body. Preferably, each layer comprises multiple fibers, and the arrangement of the fibers determines the position and size of each pore. It is not necessary for the pores to form a regular pattern. The fibers are preferably arranged such that a single pore allows a particle to pass through only if the particle size is smaller than a predetermined upper limit. The openings, i.e., the pores, in different layers are arranged offset from each other such that particles flowing through the filter as part of a gas sample cannot pass through the filter in a straight path, but only when the particles change their direction at least once, preferably multiple times, i.e., are deflected (redirected). During such changes of direction, particles often remain attached to the filter. In such a depth filter, the openings (pores) can be larger than in a sieve (surface filter), and larger particles cannot pass through the filter.

[0029] In many cases, depth filters exhibit lower aerodynamic resistance than surface filters, which function like sieves, for the same filtration effect. Furthermore, depth filters typically bind significantly more particles than surface filters until the aerodynamic resistance becomes too high, necessitating filter replacement. This characteristic allows depth filters to often last longer than surface filters.

[0030] These two design schemes, namely electrostatically charged filters and mechanical filters, can be combined. Due to this combination, electrostatically charged filters can still filter out particles even when the electrostatic filter is discharged, which often happens after a long period of use.

[0031] The filter has relatively low aerodynamic resistance, which is particularly advantageous when constructed as a depth filter and / or an electrostatically charged filter, so that the gas sample is drawn into the measuring chamber faster with lower aerodynamic resistance than with higher aerodynamic resistance, while maintaining the same inhalation process normally. For example, when the input gas mixture is a respiratory sample from the subject, the higher velocity is advantageous: the higher velocity increases the reliability of the gas sample originating from a specific desired part of the subject's respiratory system, such as the lungs or upper respiratory tract.

[0032] In one design, the filter removes all particles with the largest diameter from the flowing gas sample, said largest diameter being less than or at most the same as an upper limit. This upper limit is preferably between 1 μm and 10 μm, particularly preferably between 1 μm and 3 μm, and especially 2 μm.

[0033] Preferably, the entire input unit or at least one mouthpiece can be detachably connected to and detached from the substrate. This design facilitates compliance with hygiene requirements. For example, a subject inputs a breath sample into the input unit, and the input unit or at least the mouthpiece is used to deliver the breath sample once and then immediately emptied. Conversely, the same substrate can be used to analyze multiple gas samples sequentially. According to the invention, the filter is located inside the substrate and not inside the input unit. Therefore, the filter can also be reused multiple times. This reduces material consumption compared to a filter in the input unit. Furthermore, even if the substrate, i.e., the analytical device, is stored without the input unit, the filter protects the valve from external contamination. Due to the filter, it is rarely necessary to fit a closure over the opening in the substrate, where the fluid guiding unit connects this opening to the measuring chamber.

[0034] According to the invention, the suction unit draws a gas sample from the gas mixture flowing through the input unit and delivers it to the measuring chamber. Preferably, the volume of the gas sample is less than 10% of the volume of the gas mixture flowing through the input unit, particularly preferably less than 1%, and especially less than 0.1%. Thus, the filter is subjected to a particularly small load and is significantly less clogged by particles compared to the larger gas sample being drawn in.

[0035] The preferred valve includes a valve body and a valve body seat. When the valve is in the closed final position, the valve body rests against the valve body seat, ideally in a fluid-tight manner. When the valve is in the released final position, a gap appears between the valve body and the valve body seat.

[0036] In one design, the analytical apparatus includes a mechanical connecting element. This connecting element mechanically connects the valve body to the intake unit. As the intake unit draws in a gas sample and delivers it to the measuring chamber, the mechanical connecting element moves the valve from one endpoint to another. During this movement, the valve body moves relative to its seat. Preferably, the intake unit moves the valve from a closed endpoint to a released endpoint before drawing in the gas sample and then moves it back from a released endpoint to a closed endpoint during intake. Therefore, the processes of drawing in the gas sample and opening the valve are synchronized and overlap in time. After intake, the fluid guiding unit is then closed again. The reverse implementation is also possible. Preferably, the connecting element is capable of performing two linear movements in two opposite directions within the substrate.

[0037] Because of the mechanical connecting elements, the analytical device only needs a single actuator. This actuator moves the suction unit, thereby delivering the gas sample to the measuring chamber. It also moves the valve from one endpoint to another. Due to the connecting elements, there is no need for two separate actuators, saving structural space.

[0038] This design enables the following operation: when no gas sample is drawn in, the valve is in the closed final position. To draw in a gas sample, the following two steps are performed sequentially: In the first step, the suction unit delivers gas from the reservoir to the measuring chamber and thereby flushes the measuring chamber. Preferably, the reservoir is located inside the substrate. During flushing, the gas from the measuring chamber is conveyed from the housing of the analytical device through the fluid guide unit and delivered to the input unit. Simultaneously, or at least concurrently in time, the valve body is moved away from the valve seat by means of a connecting element, and the valve is moved to the released final position. The gas from the measuring chamber is flushed out of the analytical device. In the second step, the suction unit draws in a gas sample from the input unit. The gas sample flows through the fluid guide unit into the measuring chamber. Simultaneously, or at least concurrently in time, the valve body is moved back towards the valve seat by means of a connecting element, and the valve is moved back to the closed final position. Thus, the valve closes the fluid guide unit for as long as possible, and the measuring chamber is fluidly connected to the surrounding environment only for the longest possible time. Even when the input unit is separated from the substrate, the sealing valve and filter also separate the measuring chamber from the surrounding environment.

[0039] In a preferred design, the suction unit includes a chamber with variable volume, particularly a bellows or piston-cylinder unit. A measuring chamber is located between the chamber of the suction unit and the fluid guiding unit. The chamber of the suction unit is fluidly connected to the measuring chamber. The chamber provides the storage space described above. If the volume of the chamber increases, a negative pressure is generated in the chamber of the suction unit, thereby in the measuring chamber and thus in the fluid guiding unit, and the resulting negative pressure draws a gas sample through the fluid guiding unit into the measuring chamber. If the volume of the chamber decreases, an overpressure is generated in the chamber of the suction unit and thus in the measuring chamber, thereby flushing the measuring chamber.

[0040] The preferred mechanical connecting element connects the suction unit to the valve as follows: when the chamber is switched to the state with minimum volume, the valve is moved to the release end position. Conversely, when the chamber is switched to the state with maximum volume, the valve is moved to the closed end position.

[0041] The preferred analytical apparatus includes a heating device. The heating device is capable of heating sections of the fluid guiding unit. A filter is located within the heatable section. The heating device may include a conductive wire that heats up when an electric current flows through it. In another implementation, the heating device heats the section in a non-contact manner. A radiation source emits electromagnetic radiation, particularly infrared radiation, and the emitted radiation heats the section.

[0042] In many cases, the gas mixture flowing through the input unit comprises small droplets and / or vapor. This is particularly true when the gas mixture is a breath sample provided by the subject. Therefore, the aspirated gas sample typically also comprises small liquid droplets and / or vapor. The risk is that liquid may condense on the filter element of the filter in the fluid guide unit and, for example, drip down the filter. This condensed liquid may cause greater aerodynamic drag and / or damage to the filter element and / or distort the measurement results of the sensor assembly. Liquid is especially likely to condense on the inner walls of the fluid guide unit or on the optics of the sensor assembly.

[0043] It is known that the higher the temperature of a gas mixture, the more liquid it can absorb, all other things being equal. Therefore, the heating device reduces the risk of liquid condensation on the filter. Because the filter is located in the heated section, the risk of condensation is lower than if the heating device were in a different location.

[0044] The tubular input unit extends along the longitudinal axis. Preferably, the fluid guiding unit also extends along the longitudinal axis. Preferably, these two longitudinal axes form an angle of at least 60 degrees between them. Particularly preferred is that the two longitudinal axes are perpendicular to each other. This design facilitates the near-horizontal arrangement of the input unit's longitudinal axis and the near-vertical arrangement of the fluid guiding unit's longitudinal axis when using the analytical device. The substrate can be comfortably held in the hand. The direction in which the gas mixture exits the input unit can be easily determined.

[0045] In one design, the analytical device includes a pressure sensor. The pressure sensor is capable of measuring the pressure at a first measurement location at least once, preferably repeatedly, at a fixed scanning frequency. The first measurement location is downstream of the filter and outside the input unit. In a first implementation, the first measurement location is within or at the fluid guiding unit and there between the filter and the measuring chamber; in a second implementation, it is in the measuring chamber or on the wall of the measuring chamber; and in a third implementation, it is between the measuring chamber and the suction unit. Therefore, since the first measurement location is inside the substrate and outside the input unit, the pressure at the first measurement location often depends relatively little on the pressure already used to introduce the gas mixture into the input unit.

[0046] The analytical device is capable of determining the pressure at a first measurement location, preferably determining the time-varying curve of this pressure, and for this purpose uses at least one measurement value from a pressure sensor, preferably a signal, i.e., a sequence of measurements. The pressure at the first measurement location typically matches the pressure in the measurement chamber after the initial oscillation phase ends, and more precisely, it typically matches not only when the valve is open but also when the valve is closed. As long as the valve is closed, the pressure at the first measurement location will differ from both the ambient pressure and the pressure in the input unit.

[0047] The pressure sensor can optionally measure the pressure at a second measurement location. This second measurement location is also located within or at the fluid guide unit, but upstream of the filter. When the input unit is mounted, the second measurement location is thus situated between the suction inlet and the filter. The analytical device can preferably determine the pressure at the second measurement location, preferably a time-varying curve of that pressure, and for this purpose uses at least one additional measurement from the pressure sensor, preferably a signal.

[0048] Looking along the flow direction of the gas sample from the input unit to the measurement chamber, the first measurement position is therefore downstream of the filter, and the optional second measurement position is upstream of the filter. In other words, the filter is located between the two measurement positions.

[0049] Note: The concepts of "upstream" and "downstream" refer to the flow direction of the gas sample from the input unit to the measurement chamber.

[0050] Analytical equipment can determine the current aerodynamic resistance of a filter. The aerodynamic resistance of a filter is the quotient of the pressure differential (numerator) and the volumetric flow rate through the filter (denominator), where the pressure differential is the pressure difference between the upstream and downstream pressures of the filter, i.e., the pressure drop across the filter. In many cases, the following assumption is reasonable: aerodynamic resistance is not significantly dependent on the volumetric flow rate, and therefore the pressure differential can be assumed to be proportional to the volumetric flow rate.

[0051] The following describes an analysis of how the equipment can automatically determine the aerodynamic resistance of the filter.

[0052] The preferred analytical equipment, more precisely the signal processing and evaluation unit of the analytical equipment, such as the control equipment, can determine the volumetric flow rate through the filter and therefore through the fluid guiding unit. This volumetric flow rate occurs when the input unit is installed, the valve is opened, and the suction unit is activated.

[0053] It is possible to measure or otherwise determine volumetric flow rate using analytical equipment in various ways. It is also possible to determine mass flow rate by replacing or adding a measurement unit to the volumetric flow rate. Volumetric flow rate is the volume of fluid flowing through a fluid guide unit per unit time, while mass flow rate is the mass of fluid flowing through a fluid guide unit per unit time.

[0054] In one implementation, the analytical device determines the volumetric flow rate based on the manipulation and / or characteristics of the suction unit. This suction unit induces the volumetric flow rate through suction. Typically, the geometry of the suction unit determines the volume of the gas sample being suctioned. The duration of the suction process is determined from the manipulation. This provides at least an approximation of the sought volumetric flow rate. In another implementation, the analytical device includes a volumetric flow rate sensor.

[0055] In the second implementation, the analytical device derives the volumetric flow rate using pressures measured at both the first and second measurement locations. The device derives a time-varying curve of the pressure difference between the two measurement locations from the pressure sensor readings. This pressure difference represents the pressure drop across the filter. The analytical device derives the volumetric flow rate from this pressure difference's time-varying curve. If the filter's aerodynamic resistance has been measured in another manner, the analytical device derives the volumetric flow rate from both the pressure difference and the aerodynamic resistance.

[0056] In the third implementation, the analytical device is configured to approximately determine the volumetric flow rate through the filter by the following steps: - The pressure sensor repeatedly measures the pressure at the first measurement location.

[0057] The analytical device identifies a time period in which a sufficiently large negative pressure relative to a reference pressure occurs at a first measurement location. To identify this time period, the analytical device uses a time-varying curve of the pressure at the first measurement location.

[0058] - The reference pressure is, for example, the pressure measured by a pressure sensor at a first measurement position at at least one moment, at which time the valve is closed and therefore no gas sample is being drawn in. The reference pressure can also be the pressure measured in the surrounding environment of the analytical device.

[0059] - Negative pressure causes the gas sample to be drawn in. The analytical device derives the duration of gas sample aspiration from the identified time period.

[0060] - The analytical device determines the volume of the aspirated gas sample. The volume of the aspirated gas sample is determined with sufficient accuracy by the geometry and / or structure of the aspiration unit, particularly by the volume of the chamber of the aspiration unit, and said geometry and structure are known in advance. Typically, the volume of the gas sample does not depend consequently on the volume of the gas mixture that has been fed into the aspiration unit.

[0061] - The inhalation unit uses the quotient of the gas sample volume and the determined duration as the volumetric flow rate.

[0062] The third implementation does not require measuring the pressure at the second measuring position upstream of the filter or deriving the duration of the suction process from the drive of the suction unit. Furthermore, the third implementation does not require knowledge of the filter's aerodynamic resistance. More precisely, the aerodynamic resistance can be derived using the third implementation.

[0063] According to the fourth implementation, the analytical device further includes a volumetric flow sensor, which measures the volumetric flow rate through the filter and uses either a thermal velocity measurement principle or a laser Doppler velocimetry principle for this purpose. The fourth implementation also does not require measuring the pressure at the second measurement location or knowing the aerodynamic resistance of the filter. More precisely, the aerodynamic resistance can be derived from the fourth implementation.

[0064] The following explains the application of the design scheme just described, which is used to determine the volumetric flow rate. The analysis device, more precisely, the evaluation unit of the analysis device that processes the signal, such as a control device, can determine the current aerodynamic resistance of the filter. For the application described below, the following assumption is made that the aerodynamic resistance does not depend on the volumetric flow rate and therefore the pressure drop across the filter is proportional to the volumetric flow rate.

[0065] The above describes a method for determining volumetric flow rate when the aerodynamic resistance of the filter is unknown. Different methods are possible for analyzing how the equipment measures the pressure drop across the filter.

[0066] In one implementation, a pressure sensor measures pressure at a first measurement location and pressure at a second measurement location, wherein the first measurement location is downstream of the filter and the second measurement location is upstream of the filter. The difference between the two measured pressures provides the pressure drop.

[0067] In another design, the analytical device uses the time period mentioned above, during which a negative pressure relative to the reference pressure occurs at the first measurement location. To derive the pressure drop from this identified time period, the following assumption is preferred: if no filter is installed in the fluid guiding unit, the following process will occur: - The inhalation unit inhales a gas sample.

[0068] - The valve is opened.

[0069] - After the valve is opened, a oscillation phase occurs during which the pressure difference along the fluid guide unit disappears. After this oscillation phase ends, the pressure in the measuring chamber matches the pressure in the fluid guide unit and there matches the pressure upstream of the filter. In particular, the pressure in the measuring chamber matches the pressure at the first measuring position.

[0070] After the oscillation phase ends, the pressure difference between the pressure at the intake opening and the pressure at the first measurement location is essentially determined by the aerodynamic resistance of the filter. Therefore, the analytical apparatus preferably uses the average or maximum difference between the pressure at the first measurement location and the aforementioned reference pressure over a period of time as the pressure drop. This period falls within the time frame during which the gas sample is drawn in and after the oscillation phase.

[0071] The above describes various implementations of analytical devices that measure or otherwise determine the volumetric flow rate through a filter without using aerodynamic resistance. The analytical device determines the current aerodynamic resistance of the filter as the quotient of the pressure drop across the filter and the volumetric flow rate through the filter.

[0072] Because the filter removes particles from the flowing gas sample, the aerodynamic resistance of the filter is typically increased. Preferably, the control device repeatedly performs the determination of the current aerodynamic resistance, for example, always when N gas samples (where N>=1 is a preset number) have been drawn in since the last aerodynamic resistance determination, or when the total volume and / or mass of the gas samples flowing through the filter since the last determination has exceeded a preset upper limit.

[0073] The preferred analysis device is configured such that if the aerodynamic drag is outside a preset numerical range, the analysis device generates a corresponding message. The numerical range is characterized at least by an upper limit and optionally, additionally by a lower limit greater than zero. If the aerodynamic drag is above the upper limit, the message includes a prompt that the filter must be replaced. The analysis device preferably outputs this message in at least one human-perceptible form on its own output unit. Therefore, this message is directed to the user of the analysis device. Alternatively, this message may be additionally or alternatively transmitted to a spatially distant receiver and output on the receiver's output unit.

[0074] In one implementation, the analytical device compares the aerodynamic resistance not only to a preset upper limit but also to a preset lower limit. This lower limit is preset, for example, as follows: when the filter is correctly installed and the analytical device is not yet in use, i.e., no particles are deposited on the filter, the aerodynamic resistance of the filter is equal to or greater than the lower limit. Therefore, if the measured aerodynamic resistance is less than the lower limit, a fault exists. Possible causes of this fault include, in particular, the following: - No filter was installed in the fluid guiding unit at all. - The filter was not installed correctly, which may allow some of the gas sample being drawn to bypass the filter.

[0075] - The filter is damaged, for example, with cracks, allowing a portion of the gas sample to flow through the filter without filtering out the particles.

[0076] Ideally, messages should be generated and output even when aerodynamic drag is too low.

[0077] In one design, the analyzer can automatically check whether the filter is installed in the substrate, for example, by means of a contact switch or by detecting the pneumatic resistance in the fluid guide unit. In another design, the analyzer can detect user confirmation that the filter has been installed. It is possible that the suction unit is activated and only aspirates a gas sample when the filter is installed and preferably when the pneumatic resistance is within a preset range.

[0078] Filters with high aerodynamic resistance may cause gas samples to be drawn into the measuring chamber too slowly and / or in too small a volume, resulting in incorrect, especially low, measurements of substance concentrations. Other undesirable effects include: - Higher kinetic energy is required for inhalation.

[0079] The input of the gas mixture requires a relatively long time.

[0080] The high kinetic energy required can lead to a relatively large consumption of electrical energy. This is particularly disadvantageous, as the analytical equipment is not connected to a static power grid and therefore has its own power supply unit. As already explained, this is especially disadvantageous when a gas sample is inhaled relatively slowly from the input respiratory sample: the gas sample then often no longer originates solely from the expected part of the subject's respiratory system, i.e., from the upper respiratory tract or lungs, but also from another part.

[0081] The design scheme for measuring the aerodynamic resistance of the filter allows the analytical equipment to automatically check whether the filter is still usable or has become so severely clogged with filtered particles that it must be replaced. Filter replacement is not based solely on time or the quantity of gas sample drawn, i.e., it is independent of the filter's current condition. It is possible, but not mandatory, for a human to visually inspect the filter's current condition, due to this design. This aerodynamic resistance measurement scheme, as described above, is particularly advantageous when the filtered particles are visually only slightly different from the filter element, compared to visual inspection. Furthermore, there is no need to weigh the filter to determine its current condition.

[0082] The preferred filter is constructed as an electrostatically charged and / or mechanically functioning element. In both designs, the filter has no chemical or thermal influence on the gas sample flowing through it, ideally none at all. Therefore, the filter will not distort the measurement results of the analytical equipment.

[0083] According to the present invention, the sensor is capable of measuring the concentration of a substance in a gas sample located in a measuring chamber. Different operating principles are possible for such a sensor.

[0084] For example, the substance is a combustible gas, and the sensor is an electrochemical sensor that operates based on the principles of a fuel cell. The generated charge is used as a measure of the combustible gas concentration in the gas sample. The sensor can also be a photoelectric sensor. Electromagnetic radiation penetrates the measuring chamber, and the substance to be detected attenuates the electromagnetic radiation within a specific wavelength range. Therefore, the measured attenuation is related to the substance's concentration. The sensor can also be a photoelectric-acoustic sensor. Electromagnetic radiation causes an acoustic effect, and the substance alters this acoustic effect. For a photoelectric-ionization detector, electromagnetic radiation ionizes molecules. It is also possible that the sensor is constructed as a so-called thermal effect sensor, where the detector oxidizes the combustible substance, the oxidation of the combustible substance releases heat energy, and the released heat energy is measured and used as a measure of the combustible substance's concentration.

[0085] In one implementation, the analytical device includes two sensors connected in parallel or series with respect to the gas sample. These two sensors can utilize the same or different measurement principles. The design with two differently operating sensors provides redundancy and, in many cases, improves the reliability of accurately measuring the concentration and / or quantity of a substance.

[0086] The present invention also relates to a monitoring unit capable of monitoring the analytical apparatus according to the present invention. The monitoring unit includes the pressure sensor described above and a measurement unit for processing signals. The measurement unit can be a component of the control equipment of the analytical apparatus, or it can be spatially separated from the analytical apparatus. The pressure sensor is capable of measuring the pressure at a first measurement location. The measurement unit is capable of receiving the signal from the pressure sensor and determining the current aerodynamic resistance of the filter and comparing it with a preset numerical range. If the aerodynamic resistance is outside the numerical range, the measurement unit generates a message and outputs the message in a human-perceptible form. Attached Figure Description

[0087] The invention will now be described with reference to an embodiment. Here: Figure 1 This schematic illustrates how the electrochemical sensor works; Figure 2 A first design of the analytical apparatus according to the invention is shown in a perspective view taken from an obliquely upward angle; Figure 3 The diagram is shown in a vertical, top-down view. Figure 2 Analytical equipment; Figure 4 A cross-sectional view is shown. Figure 2 The analysis device omits the input unit; Figure 5 A second design of the analytical device according to the invention is shown in a perspective view taken almost vertically from above; Figure 6 A cross-sectional view is shown. Figure 5 Analytical equipment; Figure 7 A third design of the analytical apparatus according to the invention is shown in a perspective view taken almost vertically from above, in which the input unit is omitted; Figure 8 Another cross-sectional view is shown. Figure 7 The analysis device omits the input unit. Detailed Implementation

[0088] The analytical apparatus according to the invention is capable of examining a gas mixture for a preset substance. In this embodiment, the gas mixture is a breath sample exhaled by a subject to be examined. In this embodiment, the substance is breath alcohol. The task is to check whether the alcohol level in the subject's blood exceeds the detection limit. If the subject has ingested alcohol and the alcohol in the blood has not been completely metabolized, it is well known that the given breath sample contains breath alcohol. The invention can also be used for other substances that can be detected in a subject's breath sample.

[0089] The subject inputs a breath sample into the input unit. A portion of the breath sample is drawn from the input unit and flows into the measurement chamber. A sensor in or near the measurement chamber measures the amount of breath alcohol in the gas sample. More precisely: the sensor measures a physical detection parameter that is related to the amount (concentration) of breath alcohol in the gas sample in the measurement chamber and is therefore a measure of alcohol content.

[0090] The sensor generates a signal. The generated signal includes information about the measured breath alcohol content. For example, the sensor measures the amount of breath alcohol in a gas sample, and the evaluation unit that processes the signal derives the concentration of breath alcohol in the gas sample, and thus in the breath sample, from the amount of breath alcohol and the volume of the measuring chamber.

[0091] In this embodiment, the analytical device is one that a person can hold in their hand and hold in front of the subject's face. The analytical device includes its own power supply unit and its own output unit. The subject inputs a breath sample into the input unit. The measured breath alcohol content is displayed on the output unit in at least one human-perceptible form. Optionally, it may additionally display whether the measured breath alcohol content exceeds a preset threshold. This threshold is preset, for example, by legal regulations for car drivers and other vehicle drivers or equipment operators.

[0092] Different principles by which sensors can measure the concentration of substances in a gas mixture are known from existing technology. Several of these principles can also be applied to this invention. The sensors in the analytical apparatus according to this embodiment are, for example, electrochemical sensors, photoelectric-optical sensors, photoelectric-acoustic sensors, photoelectric-ionization sensors, or thermal effect sensors (catalytic sensors).

[0093] In one implementation, the analytical device includes an electrochemical sensor. Figure 1The operation of electrochemical sensor 12 is illustrated schematically and exemplary, wherein such operation is known in the prior art. Sensor 12 operates using breath alcohol as fuel, based on the principle of a fuel cell. Breath alcohol produces a chemical reaction in the measuring chamber. This chemical reaction triggers the flow of an electric current. The charge is measured, and the charge is a measure of the amount of breath alcohol in the gas sample Gp located in the measuring chamber 3.

[0094] Figure 1 The illustrations are not necessarily drawn to scale. The sensor assembly is indicated by reference numeral 50. The sensor assembly 50 includes a sensor 12 and a measuring chamber 3, which are surrounded by a wall 40. In this embodiment, the measuring chamber 3 has a cylindrical shape that is rotationally symmetric about a central axis MA. Of course, other geometries are also possible.

[0095] Gas sample Gp flows into measuring chamber 3 through inlet Oe and exits from measuring chamber 3 through outlet Oa. Alternatively, gas sample Gp may also exit measuring chamber 3 through inlet Oe.

[0096] Electrochemical sensor 12 includes - Measuring electrode 20, which is electrically contacted via contact wire 34. - Pairing electrode 21, which is electrically contacted via contact wire 33. -Electrolyte 28 located between the two electrodes 20 and 21 - Connecting wire 22, which electrically connects the two contact wires 33 and 34 to each other. - Measuring resistor 29 in connecting wire 22, and - Current intensity sensor 38, which measures the current intensity I flowing through the connecting line 22.

[0097] Electrolyte 28 comprises an electrolyte conductive medium, such as sulfuric acid, phosphoric acid, or perchloric acid diluted with water. In one implementation, a porous membrane provides the electrolyte 28. Ions are able to move within the electrolyte 28. The electrolyte 28 establishes an ion-conducting connection between the measuring electrode 20 and the mating electrode 21, but prohibits the flow of electrons between the two electrodes 20 and 21. The gas sample Gp reaches the measuring electrode 20 but not the mating electrode 21. The two contact wires 33 and 34 are conductive and made of a material that is not chemically corroded by the electrolyte 28, such as platinum or gold. Electrodes 20 and 21 are also made of chemically resistant materials, such as platinum or gold.

[0098] As already explained, the substance to be detected, in this case breath alcohol, triggers a chemical reaction in which the substance is oxidized, but only if a sufficient amount of the substance is present in the gas sample Gp. As a result of the chemical reaction, an electric current flows between the measuring electrode 20 and the paired electrode 21, and thus through the connecting wire 22. The current intensity sensor 38 measures the current intensity I. The evaluation unit derives the charge Q, which is the total amount of current flowing through the connecting wire 22 (coulombic analysis principle). Typically, the current flows for such a long time that the total amount of the substance to be detected, in this case, all the breath alcohol or other oxidizable substances, is oxidized in the measuring chamber 3. The charge is related to the amount of breath alcohol in the gas sample Gp.

[0099] Figures 2 to 4 A first design of the analytical apparatus according to the present invention is shown. Figure 5 and Figure 6 The second design scheme is shown, and Figure 7 and Figure 8 A third design scheme is shown. The same reference numerals have the same meaning and also... Figure 1 The meaning of . Figure 2 , Figure 3 , Figure 5 and Figure 7 The analysis device 100 is shown in a perspective view, either vertically or at an angle from above. Figure 4 The first design scheme is illustrated in a cross-sectional view from the side, and Figure 6 and Figure 8 The second or third design scheme is illustrated with two different cross-sectional views from the side.

[0100] The analysis device 100 includes a tubular input unit 70 in all design embodiments. The input unit 70 includes... -EntranceIn, -Export Out, -The tubular circumferential surface M located between the inlet In and the outlet Out, and - The suction opening AO in the peripheral surface M.

[0101] Input unit 70 schematically in Figure 2 , Figure 3 , Figure 5 , Figure 6 and Figure 7 The figure is shown in the diagram and omitted in the rest of the figures. In this embodiment, the input unit 70 has a funnel shape, which tapers gradually from the inlet Ein to the outlet Out. The input unit 70 has a central axis EA. In this embodiment, the input unit 70 is approximately rotationally symmetric with respect to the central axis EA.

[0102] If the subject wishes to input a breath sample Ap, the analyzer 100 is held in front of their mouth with the inlet Ein pointing towards the subject's mouth. The subject inputs the breath sample Ap into the input unit 70. The input breath sample Ap flows into the input unit 70 through the inlet Ein and flows parallel to the central axis EA through the input unit 70 to the outlet Out. A portion of the breath sample Ap is aspirated through the inhalation opening AO, which will be described in more detail below. The unbranched remaining portion Ap.r of the breath sample Ap flows into the surrounding environment through the outlet Out. The aspirated portion of the breath sample Ap is later fed back into the input unit 70.

[0103] The casing surrounds the substrate of the analytical device 100. The user holds this substrate in their hand while the subject provides a breath sample Ap. Only the bracket 9 is visible within the substrate.

[0104] A sensor assembly 50, comprising a measuring chamber 3 and a sensor 12, is applied to a bracket 9, wherein the sensor assembly 50 is capable of being referenced. Figure 1 It is constructed as described. Wall 40 surrounds the cylindrical measuring chamber 3. The outer surface of wall 40 is approximately square in shape. Cover plate 17 is fitted onto wall 40.

[0105] The fluid guiding unit 71 connects the suction opening AO in the input unit 70 to the measuring chamber 3. The fluid guiding unit 71 extends along the longitudinal axis FA. In this embodiment, the longitudinal axis FA of the fluid guiding unit 71 is perpendicular to the longitudinal axis (central axis) EA of the connected input unit 70. Typically, the longitudinal axis FA and the central axis MA form an angle of at least 60°.

[0106] The fluid guiding unit 71 includes - Hollow tip 1 connected to input unit 70, - A hollow connector 16 having a smaller portion 16.1 and a larger portion 16.2, and - Connector 32 on the inflow side.

[0107] The fluid guiding unit 71 establishes a fluid connection between the input unit 70 and the measuring chamber 3. The fluid connection includes segment 31 in the hollow tip 1, segment 15 in the hollow connector 16, and segment 18 below the measuring chamber 3. Segment 18 is in fluid connection with the measuring chamber 3.

[0108] In one design, an input unit 70 with a suction opening AO or a closure (not shown) can be optionally fitted onto the tip 1. According to this design, the closure is fitted when the analytical device 100 is not in use and therefore the input unit is not fitted. The closure must be removed before the input unit 70 is fitted onto the tip 1. Otherwise, the input unit 70 cannot typically be fitted. Conversely, the input unit 70 must be removed to fit the closure. Such a closure is used, which is possible but unnecessary due to the filter described below.

[0109] It is possible that the input unit 70 is used once and then discarded. In this design, the input unit 70 is detachably connected to the tip 1. This design allows the subject to place the input unit 70 in their mouth or hold it close to their face.

[0110] The measuring chamber 3 in wall 40 is located between the fluid guiding unit 71 and the suction unit. The suction unit draws the gas sample Gp from the input unit 70 through the fluid guiding unit 71 into the measuring chamber 3. In this embodiment, the suction unit is also capable of flushing the measuring chamber 3, where the "old" gas sample in the measuring chamber 3 passes through the fluid guiding unit 71 and is discharged back into the input unit 70. In one design, the old gas sample is discharged from the measuring chamber 3 when the input unit 70 is connected to the tip 1; in another design, the old gas sample is discharged from the measuring chamber when the tip 1 is not connected to the input unit.

[0111] In this embodiment, the suction unit includes a bellows 5 with a variable volume. The bellows 5 is fixed to a tubular connector 10 on the outflow side. The connector 10 is fixed to a wall 40 and establishes a fluid connection 8 between the measuring chamber 3 and the interior of the bellows 5. The wall 40 is located between the two connectors 32 and 10.

[0112] The bellows 5 has a variable volume. When the volume of the bellows 5 expands, a negative pressure is generated within the bellows 5, thereby drawing in gas, and the gas sample Gp is ​​drawn into the measuring chamber 3 through the fluid guiding unit 71. Conversely, if the volume of the bellows 5 decreases, an overpressure is generated, thereby expelling gas from the bellows 5, and the gas sample Gp is ​​expelled from the measuring chamber 3 and squeezed into the fluid guiding unit 71. As a result, the measuring chamber 3 is flushed. Typically, the volume of the drawn-in gas sample Gp is ​​approximately equal to the difference between the maximum and minimum volumes of the bellows 5.

[0113] A plate 6 is arranged inside the bellows 5, and this plate is connected to the sleeve 11. (See Figure 11.) Figure 4 Sleeve 11 is connected to rod 4. The linear movement of rod 4, parallel to the longitudinal axis FA, away from the fluid guiding unit 71, expands the volume of bellows 5. The linear movement of rod 4 in the opposite direction reduces the volume of bellows 5.

[0114] The valve can selectively close or release the fluid guiding unit 71. The valve includes a valve body 2 and a valve body seat 13 in the form of a sealing ring. When valves 2 and 13 are closed, the valve body 2 rests against the valve body seat 13, and more precisely, ideally, in a fluid-tight manner against the valve body seat. When a gap appears between the valve body 2 and the valve body seat 13, valves 2 and 13 release the fluid guiding unit 71. Only when valves 2 and 13 release the fluid guiding unit 71 can a gas sample Gp be drawn from the input unit 70 and can the gas sample flow through the fluid guiding unit 71. Figure 4 Valves 2 and 13 are shown in the released state.

[0115] In this embodiment, valve body 2 is located at the end of lever 4 pointing towards input unit 70. Movement of lever 4 not only changes the volume of bellows 5 but also causes valve body 2 to move relative to valve body seat 13. Due to lever 4, the process of drawing in gas sample Gp or flushing measuring chamber 3 through fluid guiding unit 71 is synchronized with the process of opening or closing valves 2 and 13. Particularly in one implementation, valves 2 and 13 are opened only when gas sample Gp should be drawn in or when measuring chamber 3 should be flushed, and otherwise closed.

[0116] In a preferred design, the following sequence is performed to deliver a new gas sample Gp to the measuring chamber 3: - Initially, valves 2 and 13 are closed. Bellows 5 has the largest volume.

[0117] - This moves lever 4 toward input unit 70. As a result, the volume of bellows 5 decreases, measuring chamber 3 is flushed, and valves 2 and 13 open. The gas previously in measuring chamber 3 is then transported to input unit 70 via fluid guide unit 71.

[0118] Now remove lever 4 from input unit 70 again. The volume of bellows 5 is expanded, and the gas sample Gp from input unit 70 is drawn into measuring chamber 3 through fluid guide unit 71.

[0119] - When valve body 2 has reached valve body seat 13 and therefore valves 2 and 13 are closed again, the intake of gas sample Gp ends and the movement of rod 4 ends.

[0120] In addition, Figure 4 The sealing ring 14 is shown in the image.

[0121] In the first design, the servo drive enables the lever 4 to move linearly along two antiparallel directions R.1 and R.2. A reset element (not shown) aims to move the lever 4 away from the input unit 70, thereby closing valves 2 and 13 and moving the bellows 5 to and maintaining it in the state of maximum volume. The lifting magnet 7 can be activated by applying current to it and then deactivating it. The activated lifting magnet 7 aims to move the lever 4 toward the input unit 70, and more precisely, against the force of the reset element, thereby reducing the volume of the bellows 5 and opening valves 2 and 13. Activation of the lifting magnet 7 flushes the measuring chamber 3. Once the lifting magnet 7 is deactivated again, the reset element moves the lever 4 away from the input unit 70, and the moving lever 4 shifts the bellows 5 to the state of maximum volume. The process of switching valves 2 and 13 to the closed final position and maintaining them in this closed final position consumes no electrical energy due to the reset element.

[0122] In the first design, the servo drive with the lifting magnet 7 enables the rod 4 to reciprocate linearly. In the second and third designs, the rod 4 also moves linearly along two antiparallel directions R.1 and R.2, but not via a servo drive, but via a motor 27, preferably an electric motor 27. The motor 27 rotates the output shaft 36 about the rotation axis DA via a reduction gear 42. See [reference needed]. Figure 5 In this embodiment, the rotation axis DA of the output shaft 36 is arranged parallel to the central axis EA of the input unit 70, but this parallel arrangement is not necessary.

[0123] As described below, the implementation allows motor 27 to be switched on and off, and when switched on, motor 27 enables output shaft 36 to always rotate around axis DA in the same direction of rotation DR. No servo driver is required to perform the oscillating motion.

[0124] The transmission unit 41.1 (second design) or 41.2 (third design) generates the oscillating motion of the rod 4 from the continuous rotation of the output shaft 36. Transmission units 41.1 and 41.2 include a camshaft 37, which is torsionally connected to the output shaft 36. A cam disc 39.1 (second design) or cam disc 39.2 (third design) is torsionally fixed to the camshaft 37.

[0125] The cam disk 39.1 according to the second design includes a circumferential profile that varies along its periphery. In other words, the distance between the outer contour of the cam disk 39.1 and the central axis DA varies along its periphery. Therefore, when viewed along a direction parallel to the central axis DA, the cam disk 39.1 does not have a circular shape, but rather a shape such as a worm gear. The periphery of the cam disk 39.1 includes a segment 25 with a maximum radius and a radial edge 26 in which the radius r changes abruptly, see [reference needed]. Figure 6 .

[0126] The cam disk 39.2 according to the third design scheme includes a varying surface profile. More precisely: the surface of the cam disk 39.2 pointing towards the rod 4 is arched, for example, infinitely raised. This surface has a varying distance from the plane perpendicular to the axis of rotation DA.

[0127] Rod 4 passes through bracket 19. Push rod 60 is fixed to the end of rod 4 pointing toward cam disks 39.1, 39.2. Compression spring 61 is supported on wall 40 and aims to move rod 4 toward cam disks 39.1, 39.2, thereby pressing push rod 60 against the circumferential profile of cam disk 39.1 (second design) or against the surface profile of cam disk 39.2 (third design) and holding it in contact position. Therefore, even when cam disks 39.1, 39.2 rotate about the axis of rotation DA, push rod 60 is in continuous contact with the circumferential profile of cam disk 39.1 or cam disk 39.2.

[0128] Furthermore, in this embodiment, the perforated plate 43 with multiple open sections is torsionally fixed to the camshaft 37, see [reference]. Figure 5 and Figure 7 Electrical energy is supplied to the grating 44 via two electrical contacts 45.1 and 45.2. The light source of the grating 44 emits a light beam. Depending on the rotational position of the aperture disk 43 and thus the rotational position of the cam disks 39.1 and 39.2, the emitted light beam passes through the opening in the aperture disk 43 and strikes the receiver of the grating 44 or is interrupted by the aperture disk 43. Due to the light source, the current rotational position of the cam disks 39.1 and 39.2 can be measured. In a third design, the cam disk 39.2 with a variable surface profile and the aperture disk 43 form a single component that is torsionally fixed to the camshaft 37.

[0129] Due to the orifice plate 43, the oscillating motion of lever 4 can be reliably adjusted. Adjustment allows for the aspiration of a gas sample Gp from the respiratory sample Ap, wherein the aspirated gas sample Gp includes exhaled air from at least one desired area of ​​the subject's respiratory system and ideally contains no exhaled air from at least one other area of ​​the respiratory system. To achieve this, motor 27 is actuated and moves lever 4 in an adjusted manner. The current rotational position of cam plates 39.1, 39.2 determines the current position of lever 4 and thus the current volume of bellows 5.

[0130] As already explained, the fluid guiding unit 71 connects the input unit 70 to the measuring chamber 3. Inside the fluid guiding unit 71, fluid connections are provided to three series-connected segments 31, 15, and 18. Depending on whether the valve body 2 rests against the valve body seat 13 or a gap exists, the valve with valve body 2 and valve body seat 13 either closes or releases the fluid guiding unit 71. Ideally, valves 2 and 13 should fluid-tightly seal the fluid connections 31, 15, and 18, thereby isolating the measuring chamber 3 from the surrounding environment, when gas sample Gp should not be aspirated and the measuring chamber 3 should not be flushed. This prevents: evaporation of substances from the sensor, which may be the case, especially in electrochemical sensors, or conversely, undesirable environmental impacts on the sensor, particularly particle intrusion.

[0131] However, an undesirable event may occur where particles reach between valve body 2 and valve body seat 13, thus preventing a complete fluid seal when valve body 2 rests against valve body seat 13. The following describes how the risk of such an undesirable event is reduced according to the present invention.

[0132] The analytical apparatus 100 additionally includes a filter 23 located within the fluid guiding unit 71 and upstream of valves 2 and 13, i.e., between the input unit 70 and valves 2 and 13 in the case of the integrated input unit 70. The gas sample Gp drawn from the input unit 70 first flows through the filter 23 and then reaches valves 2 and 13. The filter 23 filters out all particles larger than a preset upper limit or having other preset characteristics from the flowing gas sample Gp. This upper limit is preset by the structure of the filter 23 and is, for example, 2 μm.

[0133] In this embodiment, the filter 23 is located inside the connector 16 and also inside the connector 32. Other locations are also possible. Preferably, the filter 23 is arranged so far from the input unit 70 that the risk of the filter 23 being damaged by external influences is relatively low. On the other hand, the filter 23 is positioned so far from the measuring chamber 3 that a gap exists between the valve body 2 and the filter 23 at every possible location of the rod 4.

[0134] Filter 23 typically includes a filter element and a support surrounding and supporting the filter element. The support can be inserted into a corresponding receiving portion in the base of the analytical device 100 and then removed. The gas sample Gp flows through the filter element. Preferably, the filter element is electrostatically charged and comprises a nonwoven fabric, particularly preferably a meltblown nonwoven fabric. This embodiment achieves a filter with relatively low aerodynamic resistance and therefore a relatively small pressure drop on filter 23. Preferably, the nonwoven fabric or other filter element of filter 23 has a hydrophobic coating or is made of a hydrophobic material. This improves the reliability that moisture in the gas sample Gp drips down the filter element without condensing on it, wetting the filter element, or even passing through filter 23.

[0135] The preferred filter 23 is inserted into the gap in the housing and can be replaced by access from the outside.

[0136] In this embodiment, the gas sample Gp originates from the breath sample Ap provided by the subject and therefore has relatively high air humidity. A design has been described above in which the filter element of filter 23 is made of a hydrophobic material or has at least one hydrophobic coating. Compared to other possible implementations, this implementation reduces the risk of droplets in the gas sample Gp damaging the filter element.

[0137] Another possible measure is to heat the filter 23, preferably without contact. Due to this heating, the temperature in the section hS of the fluid guiding unit 71 where the filter 23 is located remains above the dew point of the liquid in the breathing air. This reliably prevents moisture condensation on the filter 23 in many cases.

[0138] Different implementations of a suitable heating device are possible. In this embodiment, the heating device used is located outside the fluid guiding unit 71, preferably also outside the connecting member 32, and heats the segments hS of the fluid guiding unit 71 without contact. See [link to documentation]. Figure 8The schematically illustrated, electrically driven heating device 24 includes a light source, such as at least one LED, which emits heating electromagnetic radiation eS toward the filter 23. For example, the electromagnetic radiation eS heats the connector 32, and the heating of the connector 32 is transferred to the filter 23. The illustrated location of the light source 24 should be understood as exemplary only. Heating resistors, particularly heating spiral tubes, which are incorporated into the connector 32, may also be used instead of heating devices external to the fluid guiding unit 71.

[0139] In the illustrated embodiment, the pressure sensor 46, schematically shown, repeatedly measures the pressure at a first measurement position MP.1 and optionally repeatedly measures the pressure at a second measurement position MP.2. The pressure sensor 46 may optionally include two measurement channels for the two measurement positions MP.1 and MP.2. The first measurement position MP.1 is located downstream of the filter 23, for example, within the fluid guiding unit 71 or within or at the measurement chamber 3, or between the measurement chamber 3 and the suction units 5, 6, 7, 27. The optional second measurement position MP.2 is located within the fluid guiding unit 71 and upstream of the filter 23, i.e., between the filter 23 and the input unit 70.

[0140] The control device 62, which processes signals, receives the signal from the pressure sensor 46 and derives from the signal a time-varying curve of the pressure at the first measurement position MP.1 and optionally a time-varying curve of the pressure at the second measurement position MP.2. If the pressure is measured at both measurement positions MP.1 and MP.2, the control device 62 additionally derives a time-varying curve of the difference between the two pressures.

[0141] In one design, control device 62 derives the volumetric flow rate from the suction opening AO through the fluid guide unit 71 and thus through the filter 23 to the measuring chamber 3 from the time-varying curve of the differential pressure. Typically, a noteworthy volumetric flow rate only appears when valves 2 and 13 are open. The volumetric flow rate is caused by suction units 5, 6, 7, and 27.

[0142] In one application, control device 62 derives the volume of gas sample Gp in measuring chamber 3 from the measured or otherwise determined volumetric flow rate. It is known that volume is an integral of time with respect to volumetric flow rate. The time period over which this integration is performed is preferably equal to the time period during which suction units 5, 6, 7, 27 suction gas sample Gp and therefore the pressure at the second measuring position MP.2 is less than the pressure at the first measuring position MP.1.

[0143] Another application of pressure sensor 46 is described below.

[0144] When a gas mixture flows through mechanical filter 23, a pressure drop typically occurs across filter 23. This pressure drop, the difference between the pressure upstream and downstream of filter 23, allows it to be understood with sufficient approximation as proportional to the volumetric flow rate of the gas mixture flowing through it. This quotient is called the aerodynamic resistance of filter 23. The assumption that aerodynamic resistance is generally not significantly correlated with volumetric flow rate is reasonable. If the volumetric flow rate through filter 23 and the pressure drop across filter 23 are known, the current aerodynamic resistance of filter 23 can be derived.

[0145] Filter 23 filters out particles from the flowing gas sample Gp, and these particles inevitably adhere to the surface of filter 23. This increases the aerodynamic resistance of filter 23. If the measured current aerodynamic resistance reaches the upper limit, filter 23 should be replaced. The following describes how control device 62 determines the aerodynamic resistance of filter 23.

[0146] If a new filter 23 is used, it will have an initial aerodynamic resistance. This aerodynamic resistance is typically preset by the filter's structure. If the measured aerodynamic resistance of filter 23 is less than the initial aerodynamic resistance or even equal to zero, this indicates that no filter has been installed, or that filter 23 has been installed incorrectly or is damaged.

[0147] Control device 62 measures or determines the pressure drop across filter 23 and the volumetric flow rate through filter 23. The pressure drop and volumetric flow rate occur during a time period in which valves 2 and 13 are open and during which suction units 5, 6, 7, and 27 draw in gas sample Gp.

[0148] The design for measuring pressure drop and volumetric flow rate has been described above. This design requires repeated measurement of the pressure not only at the first measurement location MP.1 but also at the second measurement location MP.2. The design described below does not require measurement of the pressure at the second measurement location MP.2.

[0149] The aerodynamic resistance of the fluid guiding unit 71 is less than that of the filter 23. If the filter 23 were not present in the fluid guiding unit 71, the following flow would typically occur: -Activate driver 7, 27.

[0150] - Increase the volume of bellows 5. At the same time, open valves 2 and 13.

[0151] - The gas sample Gp is ​​drawn into the measuring chamber 3.

[0152] - After a typically very short initial oscillation phase, the pressure in measuring chamber 3 is equal to the pressure in fluid guiding unit 71 and also equal to the pressure upstream of filter 23 there. Note: It is known that pressure propagates at approximately the speed of sound.

[0153] However, according to the present invention, a filter 23 is present in the fluid guiding unit 71. Therefore, at the latest after the start-up phase ends, the pressure drop in the fluid guiding unit 71 is essentially caused by the filter 23.

[0154] In one design, control device 62 determines, for example, the reference pressure at the first measurement position based on the measurement value of pressure sensor 46 when valves 2 and 13 are closed and when actuators 7 and 27 are deactivated. As explained above, control device 62 further determines the time-varying pressure curve at the first measurement position MP.1 when valves 2 and 13 are opened and gas sample Gp is ​​drawn in. Control device 62 derives the following information from the reference pressure and the time-varying pressure curve: - The average pressure drop on filter 23 during the period when gas sample Gp is ​​inhaled and passes through the oscillation phase, and - The time period used for inhaled gas sample Gp and the resulting duration.

[0155] At the first measurement position MP.1, the negative pressure relative to the reference pressure typically only occurs during the time period of the inhaled gas sample Gp.

[0156] Furthermore, the control device 62 determines the volume of the inhaled gas sample Gp. In this embodiment, the gas sample Gp is ​​inhaled by increasing the volume of the bellows 5. Therefore, typically, the volume of the gas sample Gp after the start-up phase is equal to the difference between the maximum and minimum volumes of the bellows 5. This volume difference is known and preset by the geometry and structure of the inhalation units 5, 6, 7, and 27.

[0157] As the volumetric flow rate through filter 23, control device 62 uses a quotient consisting of the volume of gas sample Gp and the duration for which gas sample Gp is ​​inhaled.

[0158] Control device 62 determines the current aerodynamic resistance of filter 23 by dividing the measured or determined pressure drop by the measured or determined volumetric flow rate. Preferably, control device 62 repeatedly determines the corresponding current aerodynamic resistance. For example, if the analyzer 100 has drawn in N gas samples since the last determination, where N>=1 is a preset number, or if the total volume of gas samples since the last determination is generally greater than a preset upper limit, then control device 62 re-determines the current aerodynamic resistance.

[0159] If the aerodynamic resistance of filter 23 has reached a preset upper limit, the analysis device 100 preferably generates a message in at least one human-perceptible form. This message contains information that filter 23 must be replaced. If the measured aerodynamic resistance of filter 23 has reached this limit, the analysis device 100 causes this message to be output in at least one human-perceptible form. This message informs the user that filter 23 should now be replaced.

[0160] In one design, the analyzer 100 can determine whether the filter 23 is installed. Without the filter installed, the aerodynamic resistance in the fluid guiding unit 71 is significantly lower, especially less than the initial aerodynamic resistance mentioned above. Alternatively, the analyzer 100 includes a contact switch actuated by the installed filter 23. Alternatively, the analyzer detects user confirmation that the filter 23 is installed. In one design, if the filter 23 is not installed, the control device 62 prevents the suction units 5 and 6 from being activated and drawing in a gas sample. Furthermore, the analyzer 100 preferably then generates a corresponding message.

[0161] List of reference numerals in the attached diagram: The hollow tip of the fluid guiding unit 71 is detachably connected to the input unit 70. 2. Valve body, mounted on rod 4, belonging to the fluid guiding unit 71. 3. A cylindrical measuring chamber, which receives the aspirated gas sample Gp, is surrounded by walls 40 and a cover plate 17, and has a central axis MA. 4. The lifting magnet 7 or motor 27 moves in two directions R.1 or R.2, expanding the volume of bellows 5 and causing valve body 2 to move relative to valve body seat 13. 5-corrugated pipe, belonging to the suction unit. The plate in the 6-bellows 5 is fixedly connected to the sleeve 11 and thus to the rod 4. 7. The lifting magnet can be activated and deactivated, and after activation, it moves rod 4 relative to the fluid guiding unit 71, thereby expanding the volume of bellows 5. 8. Fluid connection between the interior of measuring chamber 3 and bellows 5 9. Analytical equipment 100 substrate bracket 10 tubular outflow-side connectors are fixed to wall 40. 11. Sleeve, connected to rod 4 12 Electrochemical sensors, including electrodes 20 and 21 and electrolyte 28. The valve body seat 13, which is in the form of a sealing ring, on the connector 16 belongs to the valve in the fluid guiding unit 71. 14 sealing rings The segment in connector 15, which belongs to fluid guiding unit 71 between input unit 70 and measuring chamber 3. The tubular connector of the fluid guiding unit 71, comprising portions 16.1 and 16.2, connects the tip 1 to the connector 32. 16.1 The smaller portion of connector 16 16.2 Larger portion of connector 16 Cover plate on wall 40 of 17 The section below the measuring chamber 3 (section 18) is part of the fluid connection between the input unit 70 and the measuring chamber 3. 19 supports, with rod 4 passing through the support and being guided. 20 Measuring electrodes of sensor 12 21 Pairing electrodes of sensor 12 22. Connection wire between contact wires 33 and 34 23. Electrostatically charged and / or mechanically functioning filters in the fluid connection segment 15 between the environment and the measurement chamber 3. 24. A heating device for filter 23, including a radiation source in the form of an LED lamp, emitting electromagnetic radiation eS. The segment with the largest radius in the circumferential profile of cam disk 39.1. The radial edge in the circumferential profile of cam disk 39.1 27 Motor causes output shaft 36 to rotate in the direction of rotation DR. Electrolyte capable of conducting ions between electrodes 20 and 21 (electrode 28) 29 Measuring resistance in connection 22 The segment in tip 1 (31) represents the fluid connection between input unit 70 and measuring chamber 3. The inflow-side connector of the 32 fluid guiding unit 71 is arranged on the wall 40. 33 Contact wire for mating electrode 21 34 Contact wire for measuring electrode 20 Output shaft 36 rotates along rotation direction DR via motor 27, causing cam discs 39.1 and 39.2 to rotate. 37 Camshaft 38. Current intensity sensor, measures the intensity of the current flowing through connection wire 22. 39.1 A cam disc with an eccentric outer profile is torsionally fixed to the camshaft 37. 39.2 A cam disc with an eccentric surface profile is torsionally fixed to the camshaft 37. 40 Measurement Chamber 3 wall 41.1 The transmission unit according to the second design scheme, wherein the cam disk 39.1 has an eccentric outer contour. 41.2 The transmission unit according to the third design scheme, wherein the cam disk 39.2 has an eccentric surface profile. 42. Reduction transmission mechanism between motor 27 and output shaft 36 A 43-hole disc is torsionally fixed to the camshaft 37. 44 is a grating with a light source and a receiver, including electrical contacts 45.1 and 45.2. 45.1 and 45.2 are electrical contacts for grating 44. 46. ​​Pressure sensor, measuring pressure at a first measuring position MP.1 and optionally measuring pressure at a second measuring position MP.2. 50 Sensor assembly with measuring chamber 3 and electrochemical sensor 12 60. Push rod at the free end of lever 4 61. Compression spring, aiming to compress rod 4 towards cam discs 39.1 and 39.2. 70 tubular input units, with inlet (In), outlet (Out), circumferential surface (M), and central axis (EA). 62 control equipment 71. Fluid guiding unit, establishing a fluid connection between the suction opening AO in the input unit 70 and the measuring chamber 3, includes a tip 1, a connector 16, and a coupling 32, and has a longitudinal axis FA. 100 analytical devices, including an input unit 70, a fluid guiding unit 71, a measuring chamber 3 located in wall 40, a sensor 12, suction units 5, 6, 7, and 27, and a housing with a bracket 9. The suction opening in the peripheral surface M of the AO input unit 70 The breath sample is entered into the input unit 70 by the subject through the inlet Ein. The remaining portion of the Ap.r respiratory sample Ap that was not aspirated and flowed out of the input unit 70 through the outlet Out. Rotation axis of DA output shaft 36 The motor 27 rotates the output shaft 36 in the direction of DR rotation, thereby causing the cam discs 39.1 and 39.2 to rotate in the same direction. The central axis and longitudinal axis of the EA input unit 70 are perpendicular to the longitudinal axis FA of the fluid guiding unit 71. eS electromagnetic radiation, emitted by light source 24, heats segment hS. The longitudinal axis of the FA fluid guiding unit 71 is perpendicular to the central axis EA of the input unit 70. Gp draws (branches) the gas sample from input unit 70 and flows into measurement chamber 3, which is part of the breath sample Ap. The segment of the hS fluid guiding unit 71, which is heated by the emitted electromagnetic radiation eS. I Current Intensity In the input unit 70 The tubular circumferential surface of the M input unit 70 has a suction opening AO. The central axis of the MA cylindrical measuring chamber 3 MP.1 First Measurement Position: The measurement position used to measure the pressure downstream of filter 23, located in the fluid guiding unit 71, or in the measuring chamber 3, or between the measuring chamber 3 and the suction units 5, 6, 7, and 27. MP.2 Second Measurement Position: A measurement position used to measure the pressure in the fluid guide unit 71 and upstream of the filter 23. The output of input unit 70 Oa comes from the exit of measuring chamber 3 Oe entrance to measurement chamber 3 R.1 and R.2 are in opposite parallel directions, causing rod 4 to move along the opposite parallel direction.

Claims

1. An analysis device (100) for analyzing a gas mixture (Ap) for a preset substance, wherein the analysis device (100) comprises - a base body (9), - a sensor assembly (50) in the interior of the base body (9), - a suction unit (5, 6, 7, 27), - a fluid guiding unit (71), - a tubular input unit (70), - a valve (2, 13), and - a filter (23), wherein the sensor assembly (50) comprises a measuring chamber (3) and a sensor (12), wherein the input unit (70) - comprises an inlet (In), an outlet (Out) and a suction opening (AO) between the inlet (In) and the outlet (Out), - is connected or connectable, preferably detachably connected or connectable, with the base body (9), and - is so constituted that the gas mixture (Ap) to be analyzed is input into the input unit (70) through the inlet (In) and flows through the input unit (70) in the direction of the outlet (Out), wherein the fluid guiding unit (71) connects the suction opening (AO) with the measuring chamber (3) if the input unit (70) is connected with the base body (9), wherein the suction unit (5, 6, 7, 27) is constituted for - sucking a gas sample (Gp) from the input unit (70) through the suction opening (AO) from the gas mixture (Ap) flowing through the input unit (70), and - delivering the sucked gas sample (Gp) through the fluid guiding unit (71) into the measuring chamber (3), wherein the sensor (12) is constituted for measuring the concentration of the substance in the gas sample (Gp) in the measuring chamber (3), wherein the valve (2, 13) - is movable back and forth between a closed end position and a released end position, - closes the fluid guiding unit (71) in the closed end position, and - releases the fluid guiding unit (71) in the released end position, and wherein the filter (23) - is constituted for filtering particles from the gas sample (Gp) flowing through the filter (23), - is arranged in the fluid guiding unit (71), and - is between the suction opening (AO) and the valve (2, 13) when the input unit (70) is connected with the base body (9).

2. The analysis device (100) according to claim 1, characterized in that the valve (2, 13) comprises a valve body (2) and a valve body seat (13) and the analysis device (100) comprises a mechanical connection element (4), wherein the valve body (2) rests against the valve body seat (13) if the valve (2, 13) is in the closed end position and a distance between the valve body (2) and the valve body seat (13) occurs if the valve (2, 13) is in the released end position, and wherein the mechanical connection element (4) mechanically connects the valve body (2) with the suction unit (5, 6, 7, 27) so that if the suction unit (5, 6, 7, 27) sucks a gas sample (Gp) and delivers it into the measuring chamber (3), causes the valve (2, 13) to move from one end position into the other end position and causes the valve (2, 13) to move from the released end position into the closed end position.

3. Analysis device (100) according to any of the preceding claims, characterized in that the analysis device (100) comprises a heating apparatus (24), wherein the heating apparatus (24) is configured for heating a segment (hS) of the fluid guiding unit (71), and wherein the filter (23) is in the heated segment (hS).

4. Analysis device (100) according to any of the preceding claims, characterized in that the input unit (70) extends along a longitudinal axis (EA) and the fluid guiding unit (71) likewise extends along a longitudinal axis (FA), wherein both longitudinal axes (EA, FA) enclose an angle of at least 60° between them and preferably are perpendicular to each other.

5. Analysis device (100) according to any of the preceding claims, characterized in that the filter (23) is electrostatically charged.

6. Analysis device (100) according to any of the preceding claims, characterized in that the filter (23) comprises two layers, wherein the two layers - viewed in the direction of flow of the gas sample (Gp) through the filter (23) - are arranged successively to each other and each have a plurality of openings, wherein the openings are in particular holes formed by the fibers of the respective layer, and wherein the openings are so arranged offset to each other that a particle is deflected at least once on its path through the filter (23).

7. Analysis device (100) according to any of the preceding claims, characterized in that the analysis device (100) comprises a pressure sensor (46), wherein the pressure sensor is configured for measuring the pressure at a first measurement position (MP.1), wherein the first measurement position (MP.1) is in the fluid guiding unit (71) between the filter (23) and the measurement chamber (3) or at or in the measurement chamber (3) or between the measurement chamber (3) and the suction unit (5, 6, 7, 27), wherein the analysis device (100) is configured for - measuring the pressure at the first measurement position (MP.1) using the signal of the pressure sensor (46), - measuring or ascertaining the volume flow through the filter (23), - ascertaining the current aerodynamic resistance of the filter (23), and - if the ascertained aerodynamic resistance is outside a preset numerical range, in particular is greater than a preset upper limit, generating a corresponding message and outputting the message in at least one form perceptible to a person, wherein the aerodynamic resistance is the quotient of the pressure drop over the filter (23) and the volume flow through the filter (23), and wherein the analysis device (100) is furthermore configured for using - the measured pressure at the first measurement position (MP.1) and - the measured or ascertained volume flow through the filter (23) for ascertaining the aerodynamic resistance.

8. The analysis device (100) according to claim 7, characterized in that the pressure sensor (46) is additionally configured for measuring the pressure at a second measurement location (MP.2), wherein the second measurement location (MP.2) is in the fluid guiding unit (71) and, in the case of a set input unit (70), between the suction opening (AO) and the filter (23), and wherein the analysis device (100) is configured for - measuring the pressure at the second measurement location (MP.2) using the signal of the pressure sensor (46) and - ascertaining the pressure drop at the filter (23) and / or the volume flow through the filter (23) using the two measured pressures.

9. The analysis device (100) according to claim 7 or claim 8, characterized in that the pressure sensor is configured for repeatedly measuring the pressure at the first measurement location (MP.1), and the analysis device (100) is configured for - ascertaining a time period in which a negative pressure occurs at the first measurement location (MP.1) relative to a measured or otherwise ascertained reference pressure, - ascertaining the duration for the suction of the gas sample (Gp) using the ascertained time period, - ascertaining the volume of the sucked-in gas sample (Gp) and - ascertaining the volume flow through the filter (23) as the quotient from the volume and the ascertained duration, wherein the analysis device (100) is configured for ascertaining the time profile of the pressure at the first measurement location (MP.1) and using the time profile of the pressure for ascertaining the time period.

10. The analysis device (100) according to any one of claims 7 to 9, characterized in that the analysis device (100) is configured for - generating a message and causing this message to be output in at least one form perceptible to a person if the ascertained aerodynamic resistance of the filter (23) is less than a pre-set lower limit.

11. The analysis device (100) according to any one of the preceding claims, characterized in that the sensor (12) is configured for measuring the concentration of alcohol as a substance in the gas sample (Gp) in the measurement chamber (3).

12. A monitoring unit for monitoring an analysis device (100) according to any one of claims 1 to 6 or 11, wherein the monitoring unit comprises a pressure sensor (46) and an evaluation unit (62) for processing signals, wherein the pressure sensor is configured for measuring the pressure at a first measurement location (MP.1), wherein the first measurement location (MP.1) is in the fluid guiding unit (71) between the filter (23) and the measurement chamber (3) or at or in the measurement chamber (3) or between the measurement chamber (3) and the suction unit (5, 6, 7, 27), wherein the evaluation unit (62) is configured for - ascertaining a time period in which a negative pressure occurs at the first measurement location (MP.1) relative to a measured or otherwise ascertained reference pressure, - ascertaining the duration for the suction of the gas sample (Gp) using the ascertained time period, - ascertaining the volume of the sucked-in gas sample (Gp) and - ascertaining the volume flow through the filter (23) as the quotient from the volume and the ascertained duration, wherein the analysis device (100) is configured for ascertaining the time profile of the pressure at the first measurement location (MP.1) and using the time profile of the pressure for ascertaining the time period. - ascertain the pressure at the first measuring point (MP.1) using the signal of the pressure sensor (46), - ascertain the volume flow through the filter (23), - ascertain the current pneumatic resistance of the filter (23), and - generate a corresponding message and cause the message to be output in at least one form perceptible to a person if the ascertained pneumatic resistance lies outside a preset numerical range, in particular is greater than a preset upper limit, wherein the pneumatic resistance is a quotient of the pressure drop at the filter (23) and the volume flow through the filter (23), and wherein the evaluation unit (62) is further configured to ascertain the pneumatic resistance using - the ascertained pressure at the first measuring point (MP.1) and - the measured or ascertained volume flow through the filter (23).

13. The monitoring unit according to claim 12, characterized in that the pressure sensor (46) is additionally configured to measure the pressure at a second measuring point (MP.2), wherein the second measuring point (MP.2) is in the fluid-conducting unit (71) and, in the case of a set input unit (70), between the suction opening (AO) and the filter (23), and wherein the evaluation unit (62) is configured to - ascertain the pressure at the second measuring point (MP.2) using the signal of the pressure sensor (46) and - ascertain the pressure drop at the filter (23) and / or the volume flow through the filter (23) using the two ascertained pressures. ​

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