Method and device for determining substance portion of fluid mixture, and medical device

Abstract

The invention relates to a method and a device for determining a substance portion of a fluid mixture and a medical device. According to the invention, the individual substance properties of the mixture are measured using at least two different non-selective measuring devices or measuring methods in order to determine the fraction of the substance in the mixture by solving a system of equations.

Description

Technical Field

[0001] The invention relates to a method for determining the substance proportions of a fluid mixture, in particular a gas or a liquid, using at least two sensors.

[0002] Furthermore, the invention relates to a device for determining the substance proportions of a fluid mixture, in particular a gas or a liquid, wherein the device has at least two sensors for this purpose.

[0003] Furthermore, the invention relates to a medical device comprising such a device for determining the substance proportions of a fluid mixture. Background Art

[0004] To analyze the composition of fluid (liquid or gaseous) mixtures, measurement methods that exploit the highly selective properties of individual components in the mixture, such as spectroscopy or chemical measurement techniques, are often used. However, such selective measurement methods are often complex and / or slow. Consequently, selective analysis of the complete composition of a mixture with high temporal resolution is often impossible. In certain applications, even selectively determining the fraction of a desired substance in a mixture can be problematic.

[0005] Measuring the composition of a mixture by acquiring multiple measurement signals about the mixture is a state of the art technique. However, it is common practice to evaluate the properties of a single substance multiple times while varying parameters and to investigate its component-specific characteristics. For example, in absorption measurements, the light absorption of a gas / gas mixture is analyzed. The measurement wavelength is changed and the absorption at different wavelengths is measured. By scanning a certain wavelength range, the concentrations of multiple gases or even the complete gas composition can be inferred based on the absorption behavior at a specific wavelength. There are many similar methods, as shown in this example, which measure the composition of a gas mixture by analyzing specific material properties (such as absorption) under varying parameters (such as wavelength) using specific measurement methods (such as absorption spectroscopy).

[0006] These methods are usually very complex, expensive, and the equipment required for their implementation is bulky. Furthermore, mobile use of such equipment (e.g. in a moving emergency vehicle, with high shock and vibration loads) is usually not possible.

[0007] Such methods and devices are also used in medical technology, such as respiratory technology, where it is particularly necessary to determine the composition of the respiratory gases. Currently, the rapid selective measurement of, for example, oxygen (O2) requires complex and expensive measuring methods, which are also difficult to integrate into compact devices. Unlike CO2 measurement (for example, a filter that only allows wavelengths relevant for CO2 is arranged in front of the sensor on the receiver side), this is not possible with O2 measurement. There is no corresponding characteristic absorption range for O2, so optical O2 measurement can only be achieved using very finely tunable lasers. However, this method is very expensive and cumbersome. The respiratory-synchronous measurement of the oxygen concentration is important for good patient care, but has so far been difficult to achieve with compact devices. The solution described in this article aims to show that a combination based mainly on non-selective measuring methods allows the gas composition to be determined, so that the determination of the oxygen concentration can still be achieved. Summary of the Invention

[0008] One object of the present invention is to provide a device for determining the substance proportions of a fluid mixture which at least partially overcomes the above-mentioned disadvantages of the prior art.

[0009] This object is achieved according to the invention by a device for determining the substance proportions of a fluid mixture according to claim 1 .

[0010] A further object of the present invention is to provide a medical technology device with which the above-mentioned disadvantages of the prior art with regard to determining the composition of a mixture are at least partially overcome.

[0011] This object is achieved according to the invention by a medical technology device according to claim 11 .

[0012] Furthermore, it is an object of the present invention to provide a method for determining the substance proportions of a fluid mixture which at least partially overcomes the above-mentioned disadvantages of the prior art.

[0013] This object is achieved according to the invention by a method according to claim 13 .

[0014] Advantageous embodiments of the invention are claimed in the dependent claims.

[0015] The features of the device for determining the substance proportions of a fluid mixture, of the medical technology apparatus and of the method for determining the substance proportions of a fluid mixture disclosed below, both individually and in all possible combinations, are part of the present invention.

[0016] The basic idea of ​​the present invention is to combine a plurality of non-selective measuring methods or measuring devices to determine the composition of a fluid mixture. Due to the higher speed of the non-selective measuring methods, faster measurements can be performed overall to determine the proportion of at least one substance in the mixture.

[0017] A non-selective measuring method or measuring device is understood to be a method or device with which it is not possible to determine a specific substance fraction of a mixture directly or with the required accuracy or robustness and solely on the basis of the measurement data obtained with the method or device (as is the case with selective measuring methods or devices).

[0018] In an embodiment of the present invention, rather than primarily scanning a single material property, at least two different and mutually independent material properties are measured and evaluated.

[0019] Independent material properties are properties of the respective substances or mixtures that do not influence each other. These properties include, for example, thermal conductivity, heat capacity, the speed of sound in the respective substance or mixture, molar mass, dynamic viscosity, dielectric constant, and the refractive index or the speed of light in the respective substance or mixture. These properties can be utilized by known measurement methods for the non-selective determination of the substance proportions in a mixture.

[0020] Illustratively, in an embodiment of the present invention, the following sensors may be used to measure these material properties.

[0021] For example, thermal conductivity and heat capacity can be measured using a sensor comprising at least one heating element and a temperature sensor. If the fluid mixture is at rest, the thermal conductivity of the fluid mixture can be inferred by measuring the temperature at a known heater temperature after calibrating the sensor. If the heater temperature is modulated, the delay in the temperature change being detectable at the temperature sensor is a measure of the fluid mixture's heat capacity. In principle, both thermal conductivity and heat capacity can be measured using a suitable sensor arrangement.

[0022] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture comprises at least one thermal conductivity sensor and / or thermal capacity sensor. In some embodiments of the present invention, the sensor is configured as an integrated sensor chip.

[0023] In some embodiments of the present invention, the speed of sound is measured using ultrasonic technology. Corresponding sensors are already available on the market.

[0024] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture comprises at least one sound velocity sensor based on ultrasound technology.

[0025] The molar mass can be derived from the speed of sound. Measuring it using other methods is very complex.

[0026] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture comprises at least one sensor for determining the molar mass based on sound velocity measurement.

[0027] For example, dynamic viscosity can be measured by the pressure drop in a thin tube, for example, in which laminar flow is established. The pressure drop is directly proportional to the dynamic viscosity.

[0028] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture comprises at least one sensor for determining the dynamic viscosity based on a pressure drop measurement.

[0029] The dielectric constant of a fluid mixture can be measured using a plate capacitor through which the mixture flows. The change in capacitance is directly proportional to the dielectric constant. Among the gases measured in respiratory technology, water vapor stands out, as it differs from other gases of interest by a factor of more than ten.

[0030] In some embodiments of the present invention, the device for determining a substance fraction of a fluid mixture includes at least one dielectric constant sensor.

[0031] The difference in refractive index or light speed between different gases is very small, so in the corresponding embodiment of the present invention, the interferometer is used as a refractive index sensor or a light speed sensor.

[0032] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture comprises at least one refractive index sensor and / or a light velocity sensor, the latter comprising at least one interferometer.

[0033] If one wants to completely determine the composition of a mixture containing X different substances, then one needs at least X-1 independent non-selective measurements (measuring different substance properties) in order to be able to completely and unambiguously solve the resulting system of equations.

[0034] In some embodiments of the present invention, the following situations are utilized: in many applications, only a specific substance fraction of a mixture is of interest; and / or a specific substance has no or little influence on the properties of the substance to be measured in the mixture.

[0035] The number of required, at least essential, non-selective measuring methods / measuring devices (measuring individual substance properties) can thus be reduced to a value less than or equal to X-1, where X is the number of relevant substance portions.

[0036] The device according to the invention for determining the proportion of substances in a fluid mixture is designed to determine the proportion of at least one substance in a fluid mixture.

[0037] The device according to the invention for determining the substance proportions of a fluid mixture comprises at least two different non-selective measuring devices, each measuring a substance property of the mixture, wherein the substance properties measured by the measuring devices are different and independent of one another.

[0038] Furthermore, the device according to the invention for determining the substance proportions of a fluid mixture comprises at least one evaluation unit for evaluating the measured values ​​of at least two different substance properties acquired by the measuring device and for determining the proportion of at least one substance proportion in the mixture by combining the measured substance properties.

[0039] In some advantageous embodiments of the invention, for X proportions of the fluid mixture to be determined, the device for determining the material proportions of the fluid mixture has at least X-1 non-selective measuring devices, by which different and mutually independent material properties of the mixture can be measured.

[0040] In some embodiments of the present invention, at least two non-selective measuring devices are configured to perform respective measurements simultaneously or at least partially overlapping in time.

[0041] In some embodiments of the present invention, all non-selective measuring devices are configured to perform their respective measurements simultaneously or at least partially overlapping in time.

[0042] If different sensors are arranged one after the other in the volume flow of a fluid mixture, the measured values ​​may be offset in time because a specific volume reaches each sensor in turn. Given a known volume flow of the fluid mixture, this time offset can be compensated for in corresponding embodiments of the present invention, so that the measured values ​​of all sensors can be synchronized. To this end, in preferred embodiments, the device for determining the substance fraction of a fluid mixture includes a volume flow sensor.

[0043] In some embodiments of the present invention, the device for determining the substance proportions of a fluid mixture is designed to determine the proportions of O 2 and / or CO 2 in the mixture.

[0044] In some embodiments of the present invention, at least one measuring device of the device for determining the substance fraction of a fluid mixture includes at least one sensor for determining one of the following material properties: thermal conductivity, heat capacity, sound speed (e.g., ultrasonic sensor), molar mass, dynamic viscosity, dielectric constant or refractive index or speed of light.

[0045] In some embodiments of the present invention, the device for determining a substance fraction of a fluid mixture further comprises at least one selective sensor for selectively determining a substance fraction of at least one substance in the mixture.

[0046] In some embodiments of the present invention, the at least one selective sensor is constructed as a sensor for NDIR absorption measurement to determine the CO2 fraction, as a lambda sensor (oxygen sensor) for determining the O2 fraction, as a paramagnetic sensor for determining the O2 fraction, as an optical sensor (e.g., an optode for measurement by fluorescence quenching, in particular a pO2 optode), as an electrochemical gas sensor or as a humidity sensor (in particular by dielectric constant measurement).

[0047] In some embodiments of the invention, it is known which substances the mixture contains or which substances influence the material properties of the mixture to a relevant extent.

[0048] In some embodiments of the present invention, the device for determining the substance proportions of a fluid mixture is configured to iteratively determine at least one substance property. In corresponding embodiments, this can improve measurement accuracy.

[0049] In some embodiments of the present invention, the apparatus for determining the substance fractions of a fluid mixture comprises more than X-1 non-selective measuring devices. This can improve the robustness and / or accuracy of the measurement. Furthermore, in some embodiments of the present invention, this allows for plausibility checks on substance fractions determined by other measurements and / or for checking the presence of unknown substances in the mixture that could have a relevant influence on the measurement.

[0050] In some embodiments of the invention, the device for determining substance fractions in a fluid mixture comprises an evaluation unit, by means of which the fraction of at least one substance in the mixture can be determined by generating and solving a system of equations based on measured substance properties.

[0051] In some embodiments of the present invention, the system of equations to be solved may be linear or nonlinear.

[0052] The system of equations to be developed includes the measured material properties and their mathematical dependence on the individual substances in the mixture, taking into account at least the relevant components of the mixture.

[0053] In some embodiments of the present invention, the evaluation unit is configured to analytically solve the system of equations.

[0054] In some embodiments of the present invention, the evaluation unit is configured to numerically solve the system of equations.

[0055] In some embodiments of the present invention, the evaluation unit is configured to iteratively solve the system of equations.

[0056] In some embodiments of the present invention, the evaluation unit is designed to use at least one AI system to evaluate the measurement data acquired by the measuring device.

[0057] In some embodiments of the present invention, the evaluation unit is configured to evaluate the measurement data using a combination of analytical, numerical, iterative and / or AI-based methods.

[0058] In some embodiments of the present invention, the device for determining the substance fraction of a fluid mixture includes at least one compensation device, by which, for example, the temperature, pressure, volume flow and / or humidity of the mixture can be measured and used to compensate at least one of the other measurements performed to determine the substance fraction.

[0059] In some embodiments of the present invention, the device for determining substance proportions in a fluid mixture is designed for use in medical technology applications.

[0060] In some embodiments of the present invention, the device for determining a substance fraction of a fluid mixture is designed to determine at least one gas fraction in a respiratory gas during breathing by a patient.

[0061] The medical technology device according to the invention comprises at least one device according to the invention for determining the substance proportions of a fluid mixture.

[0062] In some embodiments of the invention, the medical technology device is designed as a ventilator, wherein the mixture is a gas mixture, ie, a respiratory gas.

[0063] In a further embodiment of the invention, the medical technology device is designed for blood gas analysis.

[0064] In some embodiments of the present invention, the medical technology device is designed to use the determined substance proportions to adjust the control of the treatment module and / or the control module.

[0065] In some embodiments of the present invention, the therapy module is configured as a breathing unit of a ventilator, and the instruction module is configured in some embodiments of the present invention to output instructions to a human assistant.

[0066] The method according to the invention for determining the proportion of a substance in a fluid mixture can be used to determine the proportion of at least one substance in a fluid mixture.

[0067] The method according to the invention for determining the substance proportions of a fluid mixture comprises at least the following method steps:

[0068] - performing at least two different non-selective measurements, each measurement measuring a material property of the mixture, wherein the material properties measured by the different measurements are independent of each other,

[0069] - combining the measured properties of the substances to determine the proportion of at least one substance in the mixture.

[0070] In some embodiments of the method, for the X components to be determined in the fluid mixture, at least X-1 different non-selective measuring methods or measuring devices are used, which measure different and mutually independent material properties of the mixture.

[0071] In some embodiments of the method according to the invention, at least two non-selective measurements are performed simultaneously or at least partially overlapping in time.

[0072] In some embodiments of the method according to the invention, all non-selective measurements are performed simultaneously or at least partially overlapping in time.

[0073] In some embodiments of the method according to the invention, the proportion of O 2 and / or CO 2 in the mixture is determined.

[0074] In some embodiments of the method according to the invention, at least one of the following material properties is measured: thermal conductivity, heat capacity, speed of sound (eg ultrasonic sensor), molar mass, dynamic viscosity, dielectric constant or refractive index or speed of light.

[0075] In some embodiments of the method according to the present invention, at least two material properties are measured among thermal conductivity, heat capacity, speed of sound, molar mass, dynamic viscosity, dielectric constant or refractive index or speed of light.

[0076] In some embodiments of the method according to the invention, in addition to the at least two non-selective measurements, at least one selective sensor is additionally used for the selective determination of at least one substance portion in the mixture.

[0077] In some embodiments of the method according to the invention, sensors for NDIR absorption measurement to determine the CO2 fraction, lambda sensors (oxygen sensors) for determining the O2 fraction, paramagnetic sensors for determining the O2 fraction, optical sensors (e.g. photoelectrodes for measurement by fluorescence quenching, in particular pO2 photoelectrodes), electrochemical gas sensors or humidity sensors (in particular by dielectric constant measurement) are used as selective sensors.

[0078] In some embodiments of the method according to the invention, it is known which substances the mixture contains or which substances influence the material properties of the mixture to a relevant extent.

[0079] In some embodiments of the method according to the invention, at least one material property is determined iteratively. In corresponding embodiments, this can improve the measurement accuracy.

[0080] In some embodiments of the method according to the invention, more than X-1 different non-selective measurement methods are used. This may improve the robustness and / or accuracy of the measurement.

[0081] Furthermore, in some embodiments of the present invention, the use of at least one additional measuring method / measuring device enables plausibility checks of substance proportions determined based on other measurements and / or a check of the presence of unknown substances in the mixture that have a relevant influence on the measurement.

[0082] In some embodiments of the present invention, at least one additional measurement method is used to measure a material property slowly but accurately using a first measurement method and to capture rapid changes in the corresponding material property using a second fast but possibly absolutely inaccurate measurement method (e.g., a measurement with strong drift).

[0083] In some embodiments of the present invention, at least one measurement method is used that is affected by at least two material properties (e.g., thermal conductivity and heat capacity). In this case, the measurement method is used multiple times in different implementations (e.g., using a heater to modulate the temperature of the mixture), wherein in each implementation, the influence of the different material properties is given different weights. In the example with thermal conductivity and heat capacity as material properties, this can be measuring the temperature of the mixture, where the temperature can be set by a controllable heater. Depending on the speed of the modulation, the measurement is mainly affected by thermal conductivity (slow modulation) or heat capacity (fast modulation).

[0084] In some embodiments of the present invention, at least one measurement method is used in which the corresponding material properties are measured in two different states of the mixture. For example, many material properties depend on temperature and / or pressure. In a corresponding embodiment of the invention, the mixture is first measured at, for example, a first temperature T1 (e.g., ambient temperature) and / or a first pressure P1. Subsequently, the corresponding parameters are changed without changing the composition of the mixture and the measurement is repeated. For example, to this end, the mixture is heated (or cooled) to a temperature T2, or the pressure is changed to a value P2. If the material properties of the individual components of the mixture have significantly different temperature or pressure behaviors, re-measuring will provide new information about the composition of the mixture.

[0085] In some embodiments of the method according to the invention, the fraction of at least one substance in the mixture is determined by automatically constructing and solving a (possibly linear) system of equations based on measured properties of the substances.

[0086] In some embodiments of the method according to the present invention, the system of equations established using the determined material properties is solved analytically.

[0087] In some embodiments of the method according to the present invention, a system of equations established using the determined material properties is solved numerically.

[0088] In some embodiments of the method according to the present invention, the system of equations established using the determined material properties is solved iteratively.

[0089] In some embodiments of the present invention, the iterative solution of this system of equations works as follows: Even if material property S1 cannot be selectively used to determine the fraction of a substance in a mixture, it may be dominated by material A1. In the first iterative stage, it is assumed that the measurement of material property S1 is determined solely by material A1. The fraction of material A1 is then determined first, and the system of equations with X equations is reduced to one.

[0090] In some embodiments of the present invention, at least one material property S2 that is independent of the material property S1 is similarly used to estimate the material fraction A2 or other material fractions, thereby further reducing the set of equations to be solved.

[0091] In some embodiments of the present invention, in at least one iteration phase, at least one substance fraction is estimated using empirical values. In a particular mixture (e.g., air or breathing air), certain substances (e.g., argon or nitrogen) typically occur at specific concentrations. In corresponding embodiments of the invention, these values ​​are used for at least the initial estimate in the first iteration phase, thereby reducing the system of equations accordingly.

[0092] In some embodiments of the present invention, substances with similar effects on a particular substance property are grouped together and treated as a single substance in the corresponding iteration. In some embodiments of the present invention, substances with similar effects on all measured substance properties are treated as a single substance when solving the system of equations if the determination of the individual contributions of these substances in the mixture is irrelevant for the particular application.

[0093] If all substance shares in the mixture have been determined at the end of the first iteration phase, these resulting values ​​are reused in at least one further iteration phase, in which the influence of several or all substances on the respective substance properties is taken into account to refine the determination of the substance shares in the mixture. This allows for a refinement of the analysis. The accuracy of the determined substance shares increases with further iteration phases.

[0094] In some embodiments of the method according to the invention, at least one AI system is used to evaluate the measurement data acquired by the measuring device.

[0095] In some embodiments of the present invention, elements of numerical, iterative and / or AI-supported substance share determination may also be used in combination.

[0096] In some embodiments of the method according to the invention, at least one value of the temperature, pressure, volume flow and / or humidity of the mixture is measured and used to compensate at least one of the other measurements performed to determine the substance fraction.

[0097] In some embodiments of the method according to the invention, the method is used in medical technology applications.

[0098] In some embodiments of the method according to the invention, at least one gas fraction in the respiratory gas during breathing of the patient is determined.

[0099] In some embodiments of the method according to the invention, at least one device according to the invention for determining a substance portion in a fluid mixture or a medical technology device according to the invention is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Exemplary embodiments of the present invention are shown in the accompanying drawings explained below, in which:

[0101] Figure 1 : Schematic block diagram of a device according to the present invention for determining the proportion of at least one substance in a fluid mixture,

[0102] Figures 2 to 4 : Schematic block diagram of the device according to the invention for determining the proportion of at least one substance in a fluid mixture in a side-flow configuration in three different configurations,

[0103] Figure 5 : A sensor configuration of the device according to the invention for determining the proportion of at least one substance in a fluid mixture,

[0104] Figure 6 : Schematic block diagram of a device according to the invention for determining the proportion of at least one substance in a fluid mixture in a mainstream configuration,

[0105] Figure 7 : a diagram of different iteration stages for determining the proportion of at least one substance in a fluid mixture in a corresponding method according to the invention,

[0106] Figure 8 : Schematic diagram of measurement value processing according to the present invention. DETAILED DESCRIPTION

[0107] Figure 1 A schematic block diagram of a device (1) for determining the proportion of at least one substance in a fluid mixture (10) according to the present invention is shown. The device (1) for determining the proportion of at least one substance in a fluid mixture (10) comprises an evaluation unit (2), two non-selective sensors (3), a selective sensor (4), and a compensation device (5) for acquiring measured values ​​about the fluid mixture (10). The evaluation unit (2) is designed to retrieve and evaluate the measured values ​​in order to determine the proportion of at least one substance in the fluid mixture (10).

[0108] In the embodiment of the invention shown, the evaluation unit ( 2 ) can call up the AI ​​system ( 6 ) to determine the substance proportions of the fluid mixture ( 10 ).

[0109] At least one determined substance fraction of the fluid mixture (10) can be output via an output unit (7), for example as a display on a monitor, as an acoustic output or as a digital data packet.

[0110] exist Figure 2 、 3 4 show different embodiments of the device (1) according to the invention for determining the proportion of at least one substance in a fluid mixture (10) in a side-flow configuration.

[0111] Figure 2 The arrangement of a non-selective sensor (3) in a side stream (21) is shown, which branches off from the main stream (20) of the fluid mixture (10) at a sampling point (22). The fluid mixture (10) is conveyed to the side stream (21) by a suction pump (8) arranged downstream of the sensor (3) in the flow direction and passed through the sensor (3) for measurement. According to the invention, embodiments with at least one selective sensor are also possible.

[0112] according to Figure 3 In the embodiment shown, the suction pump ( 8 ) is located upstream of the sensor ( 3 ) in the flow direction in the side stream ( 21 ).

[0113] Figure 4 An embodiment is shown with two sensors (3) arranged in parallel, respectively labeled M2 and M3.

[0114] exist Figure 5 FIG. 1 shows a sensor arrangement 3 for measuring at least three measured values ​​in parallel. A fluid mixture (10) can be introduced into the region of the sensor arrangement (3) via a line (here in the form of a main flow line (20) or a bypass line (21)). The sensor arrangement (3) comprises a dielectric constant sensor (3') in the form of a plate capacitor, a sound velocity and / or volume flow sensor (3") in the form of an ultrasonic sensor, and a viscosity sensor (3'") in the form of a differential pressure sensor.

[0115] The differential pressure is detected by pressure sensors placed at the inlet and outlet of the plate capacitor. In addition, the space between the capacitor plates is used for ultrasonic measurement.

[0116] With appropriate arrangement, a compact sensor configuration can be achieved (3), which is particularly important in mobile applications.

[0117] Figure 6A medical device (15) is shown, which is designed as a ventilator and has a device (1) for determining the proportion of at least one substance in a fluid mixture (10), which is integrated into a hose system (23) of the ventilator in terms of a sensor (here represented as a non-selective sensor (3)).

[0118] exist Figure 7 The process for iteratively determining the substance fractions of a fluid mixture (10) according to an advantageous embodiment of the invention is shown in FIG. Based on the initially determined measured values ​​M1, M2 ... Mn, the substance fractions C1', C2', ... Cn' are determined in a first step, using estimated values ​​E1', E2', ... En'. Based on the determined substance fractions, in a second iterative stage, improved estimated values ​​E1", E2", ... En" are used to determine the now more precise substance fractions C1", C2", ... Cn". Depending on the available time and computing resources, embodiments of the invention can also implement more than two iterative stages.

[0119] Figure 8 The mathematical evaluation of measured values ​​acquired using sensors ( 3 ) by an evaluation unit ( 2 ) in order to determine the substance proportions C1 , . . . Cn of a fluid mixture ( 10 ) is schematically shown.

Claims

1. A device (1) for determining the substance content of a fluid mixture (10), the device comprising at least two different non-selective measuring devices (3), each of which is configured to measure a substance property of the mixture (10), wherein the substance properties measured by the measuring devices (3) are different and independent of each other, the device further comprising at least one evaluation unit (2) for evaluating the measured values ​​of at least two different substance properties acquired by the measuring devices (3) and for determining at least one substance content in the mixture (10) based on a combination of the measured substance properties.

2. The device (1) according to claim 1, characterized in that For X proportions to be determined in a fluid mixture, the device has at least X-1 non-selective measuring devices (3), by means of which different and mutually independent material properties of the mixture (10) can be measured.

3. The device (1) according to any one of the preceding claims, characterized in that At least two non-selective measuring devices (3) are designed to perform respective measurements simultaneously or at least partially overlapping in time or with a measurable or known time offset, so that the individual measurements can be synchronized.

4. Device (1) according to any one of the preceding claims, characterized in that The device is designed to determine the proportion of O2 and / or CO2 in a mixture (10).

5. Device (1) according to any one of the preceding claims, characterized in that At least one measuring device (3) comprises at least one sensor for determining one of the following material properties: thermal conductivity, heat capacity, speed of sound, molar mass, dynamic viscosity, dielectric constant or refractive index or speed of light.

6. Device (1) according to any one of the preceding claims, characterized in that The device additionally comprises at least one selective sensor (4) for selectively determining the proportion of at least one substance in the mixture (10).

7. Device (1) according to any one of the preceding claims, characterized in that The device is designed to iteratively determine at least one material property.

8. Device (1) according to any one of the preceding claims, characterized in that The device comprises an evaluation unit (2) with which the proportion of at least one substance in a mixture (10) can be determined by constructing a system of equations based on measured properties of the substances and solving the system of equations.

9. Device (1) according to any one of the preceding claims, characterized in that The device comprises a compensation device (5) with which, for example, the temperature, pressure, volume flow and / or humidity of the mixture (10) can be measured and used to compensate at least one of the other measurements performed to determine the substance proportions.

10. Device (1) according to any one of the preceding claims, characterized in that The device is designed to determine at least one gas portion in a respiratory gas during breathing by a patient.

11. A medical technology device (15) comprising at least one device (1) for determining the substance proportions of a fluid mixture (10) according to any one of claims 1 to 10.

12. The medical technology device (15) according to claim 11, characterized in that The device is designed as a ventilator, and the mixture (10) is a gas mixture.

13. A method for determining the substance proportions of a fluid mixture (10), comprising at least the following method steps: - performing at least two different non-selective measurements, wherein a material property of the mixture (10) is measured in each case, and wherein the material properties measured by the different measurements are independent of one another, - combining the measured substance properties to determine the proportion of at least one substance in the mixture (10).

14. The method according to claim 13, characterized in that For X proportions to be determined in a fluid mixture (10), at least X-1 different non-selective measuring methods or measuring devices are used, which measure different and mutually independent material properties of the mixture (10).

15. The method according to any one of claims 13 and 14, characterized in that At least two non-selective measurements are performed simultaneously or at least partially overlapping in time or with a measurable or known time offset, wherein the individual measurements are synchronized.

16. The method according to any one of claims 13 to 15, characterized in that The proportion of O2 and / or CO2 in the mixture (10) is determined.

17. The method according to any one of claims 13 to 16, characterized in that Measuring at least one of the following material properties: thermal conductivity, heat capacity, speed of sound, molar mass, dynamic viscosity, dielectric constant, or refractive index or speed of light.

18. The method according to any one of claims 13 to 17, characterized in that In addition to the at least two non-selective measurements, at least one selective sensor is additionally used to selectively determine at least one substance portion in the mixture (10).

19. The method according to any one of claims 13 to 18, characterized in that At least one material property is iteratively determined.

20. The method according to any one of claims 13 to 19, characterized in that The substance fraction of at least one substance in the mixture (10) is determined by automatically creating and solving a system of equations based on measured substance properties.

21. The method according to any one of claims 13 to 20, characterized in that At least one value of the temperature, pressure, volume flow and / or humidity of the mixture is measured and used to compensate at least one of the remaining measurements performed to determine the substance fraction.

22. The method according to any one of claims 13 to 21, characterized in that At least one gas fraction in a breathing gas during breathing by a patient is determined.

23. The method according to any one of claims 13 to 22, characterized in that Use of at least one device (1) according to any one of claims 1 to 10 or a medical technology apparatus (15) according to claim 11.

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