Measuring device for measuring intensive measurand

Abstract

To provide a measuring device for measuring an intensive measurand, in particular the concentration or temperature of a substance emitted by a body by diffusion.SOLUTION: In a measuring device 1 including at least one measuring chamber 6 which can be placed on a body to be examined, openings 8, 10 are provided in which at least three sensors for measuring intensive measurand are arranged in the measuring chamber, the sensors being arranged at different distances from the body to be examined during the measurement, and an evaluation device is provided which receives the values measured by the sensors and determines the total value of the intensive measurand variables from the at least three measured values and the substance or energy diffusion rates.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The invention relates to a measuring device for measuring an intensive measurand, in particular the concentration of a substance emitted or absorbed by a body by diffusion, or the temperature, according to the precharacterizing part of claim 1, as well as to a method for measuring an intensive measurand, in particular the concentration of a substance emitted or absorbed by a body by diffusion, or the temperature, according to claim 16. [Background technology]

[0002] For example, the diffusion behavior of an object is of interest for the evaluation of an object, especially an industrial membrane or a biological membrane.The object can be, for example, a biological membrane.The biological membrane can be, for example, a skin surface.Currently, prior art can measure the intensive measurand, that is, the concentration of the substance released by the object through diffusion.From this, the diffusion rate J of the substance through the membrane can be determined, which can be used as a measure of the diffusion behavior of the membrane. For this purpose, a device such as that described in German Patent No. 2553377 is used. This device has at least one measurement chamber with two openings, one of which can be placed on the membrane under test. Two sensors are placed in the measurement chamber, and the sensors are positioned at different distances from the object under test during the measurement. In this way, the diffusion rate can be determined.

[0003] Previously known prior art measurement chambers have only one opening and one sensor, and a freezing plate is then provided opposite the first opening, acting as a diffusion sink.

[0004] However, there is a growing need to make this measurement faster and more reliable. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent No. 2553377 Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide a measurement device and method for measuring intensive measurands that allows faster and more reliable measurements.

[0007] This object is achieved by the features of claims 1 and 16. [Means for solving the problem]

[0008] The invention advantageously provides a measuring device for measuring an intensive measurand, in particular the concentration of a substance released by an object by diffusion, or a temperature, comprising at least one measuring chamber with at least one opening, which opening can be placed on the object to be examined, in which at least three sensors for measuring the intensive measurand are arranged, the sensors being arranged at different distances from the object to be examined during the measurement, and an evaluation device is provided which receives the values measured by the sensors and determines a total value of the intensive measurand from the values measured at the at least three different distances from the object.

[0009] An intensive measurand is a state variable that does not change as the size of the system under consideration varies. In this case, the intensive measurand can be the concentration of a substance released by an object by diffusion, or temperature. The intensive measurand can also be pressure, voltage, or any kind of concentration or density. Intensive measurands can be measured directly or indirectly.

[0010] The measurement device comprises at least one measurement chamber having at least one opening, the opening being placeable on an object to be inspected.

[0011] It is particularly preferred that the measurement chamber has at least two openings, at least one of which can be placed on the object to be examined, thus forming an open measurement chamber.

[0012] Alternatively, the measurement chamber may have only one opening that can be placed over the object under test, with a frozen plate on the opposite side of the opening acting as a diffusion sink. Such a measurement chamber is called a closed measurement chamber.

[0013] The present invention has the advantage that the associated sensor has several spatially resolved values at different distances from the membrane, and by evaluating all the values, more accurate results can be obtained. Measurement results are also available more quickly.

[0014] Preferably, calculation rules are stored in the evaluation device, on the basis of which the evaluation device determines the total value.

[0015] At the beginning of the measurement, for example, when the device is placed on the skin, it takes a certain amount of time for the substance released from the object by diffusion to reach each sensor. Therefore, the sensor cannot immediately measure the corresponding value, and it takes time for the measurement value to stabilize. Such a process can be taken into account in the stored calculation rules.

[0016] As calculation rules, for example, model functions can be stored in the evaluation device or in a downstream separate evaluation unit for an approximate simulation of the actual course of the intensive measured quantity to be determined.

[0017] After the measuring device is placed on the object to be inspected, for example, the temperature measurement determined by the sensor is the final convergence temperature (T final ) as the initial measurement value (T initial ) to the actual object temperature value, the sensor of the measuring device does not reach the actual object temperature or the final convergence temperature (T finalA certain compensation period is required to measure the actual object temperature so that it is adjusted to the actual object temperature. The compensation period for the measuring device can be up to 300 seconds.

[0018] According to the present invention, after the measuring device is placed on the surface of the object, the initial temperature (T initial ) and then calculate the actual object temperature or the final convergence temperature (T final To simulate the time course of temperature measurements up to the final convergence temperature (T final A model function for determining the final object temperature value or final convergence temperature (T) can be simulated. The model function is based on measurements recorded during a short measurement period after the measuring device is placed on the object while the temperature is still equilibrating. final In particular, the exponential function can be stored as a model function, for example for the temperature course, in the evaluation device or in a separate downstream evaluation unit.

[0019] Particularly preferably, the following functions are stored in the evaluation device or in a separate downstream evaluation unit as model functions for the temperature course of the sensor of the measuring device:

[0020]

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[0021] where: T0 = temperature at time t=0, T1 is the final convergence temperature at t=∞, τ = time constant of the exponential function in [1 / s], t is the time or period in [s], and T is the current temperature at time t. For a specified period of time after the measuring device is placed on the object to be measured, the temperature measurement T ti is the specified time t i The measured value is determined by the sensor at . Preferably, a minimum measurement period of 20 to 30 seconds is selected for determining the measured value. It is particularly preferred that the start of the measurement period is selected from a period in the range of 10 to 20 seconds after placing the measuring device on the object. The time constant τ of the model function can be considered as an unknown quantity of the model function or can be determined for the measuring device by measuring the actual temperature course and stored in the evaluation device. Particularly preferably, τ can be set to a value in the range of 1 / 60 to 1 / 90 [1 / s].

[0022] In general, the variable T0 is the temperature at the point t=0 for an assumed model function to be determined as an unknown, or the temperature progression over a period t approximated by the model function. However, the temperature T0 can be determined by the initial temperature (T initial ), or any intermediate temperature whose temperature course is approximated via a model function.

[0023] The final convergence temperature T1 at time t=∞ is the actual object temperature (T final ) corresponds to

[0024] The sum of the intensive measurements can be used as the current temperature measurement T measured at time t, which can be calculated from the sensor measurements using calculation rules.

[0025] The two unknowns of the model functions T0 and T1, or the three unknowns of the model functions τ, T0, and T1, can be determined by using the Levenberg-Marquardt algorithm or approximated from pairs of measurements.

[0026] The Levenberg-Marquardt algorithm combines robust statistical methods (maximum likelihood estimators) in an iterative procedure to select measurement points whose values do not fit the model function based on the distribution function of the residuals. Improved estimates of the model parameters can then be made for the reduced set of measurement points. The object to be tested can be any diffusion source or sink. Preferably, the object is an industrial membrane or a biological membrane. The biological membrane can be, for example, the surface of the skin.

[0027] The sensor can directly or indirectly measure the concentration c of a substance released by an object, for example by diffusion. The concentration gradient ∇c can be calculated from the spatial concentration distribution c(z). From this, the diffusion rate J of the corresponding substance released by diffusion can be calculated according to Fick's law using the substance pair-specific diffusion constant D:

[0028]

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[0029] The diffusion constant is known for a particular substance pairing and can be found in the literature. Alternatively, the diffusion constant can be determined experimentally. The diffusion constant depends on the pressure and temperature. However, the diffusion constant is known for a particular pressure and temperature. In principle, the concentration gradient can be determined from measurements of c(z) at two points z1 and z2. For this purpose, the value of the gradient must be estimated from the two measurements. This is possible, for example, with the following linear difference method:

[0030]

number

[0031] However, a spatially more resolved concentration measurement allows the concentration gradient to be derived from the measurement with much greater confidence. n Concentration c(z i ), the measurement points can be considered as interpolation points of any parameterizable function. For example, this can be a polynomial p(z) of degree k.

[0032]

number

[0033] By known numerical methods, the polynomial parameters a0 to a are determined so that k-1 can be determined:

[0034]

number

[0035] This allows us to calculate the analytical derivative of the concentration ∂c / ∂z:

[0036]

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[0037] If the gradient of p is a non-constant function, it can be used to determine the position-dependent gradient. Since the target variable to be determined is the diffusion rate J, both the determination of the parameters of p and the calculation of ∇c(z) can be chosen, for example, so that the time course of J is as stable and robust as possible to disturbances, or so that it responds as quickly as possible after the measuring device is placed on the surface.

[0038] The substance released by the object through diffusion can be water vapor. In the case of the object, such as skin, this is called transepidermal water loss. For this purpose, the diffusion rate of water vapor through the skin is determined as a measurement value. Such a measurement value is called the TEWL value.

[0039] Calculation rules stored in the evaluation device can weight the values measured by the sensors differently in order to determine the total value of the intensive measure.

[0040] This has the advantage that more accurate results are obtained much faster: when the device is placed back on the object, a sensor placed closer to the object will measure the corresponding value faster than a sensor placed further away, since it takes a certain amount of time for the amount of material released by diffusion to reach the corresponding sensor.

[0041] For each device, test measurements can be performed and for a particular device, it can be stored which values at which times of the measurement and how they are weighted to achieve the best value.

[0042] The calculation rules stored in the evaluation device may use linear, non-linear or robust estimators in determining the sum values. Several robust estimators are known. Such a robust estimator has the advantage that substantially deviating values are not taken into account, thus making it possible to obtain more accurate results.

[0043] The sum is a value determined from all measurements. This value is considered to represent the actual intensive measurand. If measurements are performed over a long period of time, the measurements are very stable for all sensors, and the sum can be, for example, the average value of all measurements.

[0044] However, depending on the application of the device, different calculation rules may exist, for example, different weightings of the sensor measurements may be applied at the start of the measurement, as already mentioned above. For example, even if the individual values fluctuate greatly due to turbulence in the environment, this can be recorded and taken into account. For example, a robust estimator cannot take these widely fluctuating values into account.

[0045] The total value may be an estimate that the evaluation device determines based on calculation rules, which take into account the time course of the total value.

[0046] Through test trials, for example, the time course of the sum over time can be known, where when a new measurement is started, the device is placed on the object, and the first measurement value is available, an estimate of the sum can be determined based on the stored typical time course of the sum.

[0047] The sensor can be located in the center or on a side wall of the measurement chamber.

[0048] The measurement chamber may comprise at least one sidewall, and the at least three sensors may be positioned on the at least one sidewall at different distances from the object under inspection.

[0049] Alternatively, the sensor may be mounted in the center or central region of the measurement chamber.

[0050] At least one sidewall may be disposed between the first and second openings.

[0051] The measurement chamber may have a circular cross section.

[0052] The at least three sensors may be arranged in at least three rows, the at least three rows being positioned at different distances from the object under inspection, with at least one sensor per row.

[0053] It is also possible to provide at least five sensors. Thus, there can be at least five rows, with several sensors per row. For example, six sensors can be arranged per row, for a total of at least 30 sensors.

[0054] The sensor can measure the concentration of a substance released by the object by diffusion. The sensor measuring the concentration of a substance released by diffusion can further measure temperature and / or relative humidity. Alternatively, in addition to the sensor measuring the concentration of a substance released by diffusion, at least three temperature sensors and / or sensors for measuring relative humidity can be provided to measure temperature and / or relative humidity, which are also positioned at different distances from the object to be inspected during measurement.

[0055] The evaluation device may also receive temperature and / or relative humidity measurements and determine a total temperature value and / or a total relative humidity value based on the measurements.

[0056] Additional temperature sensors and / or sensors for relative humidity may also be placed on the side walls or in the central region or center of the measurement chamber.

[0057] According to the present invention, there is provided a method for measuring an intensive measurand, in particular the concentration of a substance released by an object by diffusion, or a temperature, the method comprising: placing at least one measurement device having at least three sensors for measuring intensive measurands on the object to be inspected, the measurement chamber having at least one opening placed on the object to be inspected; Including, The measurement chamber allows the sensor to be positioned at different distances from the object under test during measurement. It is placed on The evaluation device receives the values measured by the sensors, and the sum of the intensive measurands is calculated based on the measured values. value is determined by the evaluation device.

[0058] To determine the total value, a calculation rule used to determine the total value can be stored.

[0059] In determining the total value, the values of the calculation rules measured by the sensors can be weighted differently.

[0060] Measurements of sensors placed closer to the membrane under test can be weighted more highly.

[0061] Different weighting allows for more reliable values to be determined more quickly.

[0062] A robust estimator can be used to determine the sum value.

[0063] It is also possible to determine the value of an intensive measure for a particular distance from the surface that is not directly measured by the sensor.

[0064] The presence of different measurement values from sensors located at different distances from the object under test allows for the determination of a function that represents the dependence of values on the distance from the film. In this way, values can also be determined for specific distances that are not directly determined by the sensor. In this way, intensive measurands can also be determined directly on the object surface. If temperature or relative humidity is measured as an intensive measurand using the sensor or an additional sensor, it is possible to determine the temperature or relative humidity on the object surface.

[0065] It may further indicate the concentration of the substance released by diffusion, the temperature or relative humidity in the immediate environment outside the second opening of the sensor.

[0066] In addition, the temperature can be measured at least three points at different distances from the object.

[0067] In the following, exemplary embodiments of the invention are explained in more detail with reference to the drawings, in which: [Brief explanation of the drawings]

[0068] [Figure 1] FIG. 1 shows a measuring device for measuring the amount of a substance released by an object by diffusion. [Figure 2] FIG. 2 is a plan view of the measurement chamber. [Figure 3] FIG. 1 shows a cross section through a measurement chamber. [Figure 4] 10 also shows a cross section through the measurement chamber and a cross section through the touchdown cap. [Figure 5] FIG. 1 shows the time course of measurements on the surface of the object (continuous curve) and on the second opening of the measuring device (dashed curve), as well as the extrapolation of water vapor concentration, temperature, and relative humidity. [Figure 6] FIG. 1 illustrates the extrapolation of water vapor concentration as a function of sensor position relative to the object. DETAILED DESCRIPTION OF THE INVENTION

[0069] 1 shows a measurement device for measuring an intensive measurand. In an exemplary embodiment of the invention, the concentration of a substance emitted by an object 5 by diffusion is measured.

[0070] A handle 2 is shown. A head 4 having a measurement chamber 6 is disposed on the handle. In the exemplary embodiment shown, the measurement chamber 6 has at least two openings 8 and 10, one of which can be placed on the object 5 to be inspected, at least two openings 14. In this case, opening 8 can be placed on the object 5 to be inspected. The measurement chamber 6 is shown in a plan view in FIG. 2. The measurement chamber 6 has a circular cross-section as can be seen in FIG. 2.

[0071] Figure 3 shows a cross section through the measurement chamber 6. It can be seen that a number of sensors 12 are arranged on the side wall 14 of the measurement chamber 6. The sensors 12 are arranged in columns and rows, adjacent to each other or overlapping each other. Five sensors are arranged in a row, overlapping each other. Six sensors are arranged in a row, so that on average three rows of sensors 12 are visible.

[0072] The sensor 12 directly or indirectly measures the concentration of the substance released by diffusion.

[0073] The object 5 can be a biological or industrial membrane. The measurement chamber 6 can be placed on the object 5. The biological membrane can in particular be a skin surface.

[0074] Additionally, the illustrated sensor 12 may measure temperature as an intensive measurand, or a separate sensor may be provided to measure temperature, or multiple sensors may be provided to measure temperature.

[0075] An evaluation device 16 is arranged in the handle 2 or externally.

[0076] The evaluation device 16 receives the values measured by the sensors 12 and determines a total value of the concentration of the substance released by diffusion from at least three measured values. If 30 sensors are provided, at least 30 sensor measurements are provided. Preferably, calculation rules are stored in the evaluation device 16, on the basis of which the evaluation device 16 determines the total value.

[0077] The calculation rules, and therefore the evaluation device 16, can weight differently the values measured by different sensors 12. For example, the values of those sensors 12 that are positioned closer to the object under inspection can be weighted higher. The sensors 12 are less susceptible to interference from turbulence. Furthermore, these sensors 12 allow measurements to be obtained more quickly after the measuring chamber 6 is placed on the object again. Substances released by diffusion must reach the sensors 12 first after placing the measuring device 1 on the object. Therefore, the sensors 12 can only measure substances released by diffusion after a certain time.

[0078] Figure 4 also shows a cross section through the device, showing an additional touchdown cap, which is used to protect the skin surface, especially during skin surface inspection.

[0079] FIG. 5 shows the time course of measurements on the surface of the object (continuous curve) and on the second opening of the measuring device (dashed curve), as well as the extrapolation of water vapor concentration, temperature, and relative humidity. Only after a certain time does a stable value become reached. However, an estimate of the total value can also be determined based on measurements already taken at an earlier time. To determine the estimate, the evaluation device 16, and thus the calculation rules, take into account the time course of the total value and / or the measurements. The time course can be determined by comparative tests, for example, by determining a typical time course function. If initial values are currently available, the expected stable total value can be determined based on these initial values and the stored time course function. Even if the measurements continued for a longer period, turbulence or other disturbances may occur.

[0080] Measurements that differ significantly from other measurements may not be taken into account when determining the total value.

[0081] Thus, in the further course of the measurement, different weightings can still be applied.

[0082] For example, the calculation rule may use a robust estimator to determine the sum value.

[0083] It is also possible to determine the concentration of released substances by diffusion at the surface of an object.

[0084] It is also possible to determine the concentration of the released substance by diffusion in the immediate vicinity of the measuring device.

[0085] For this purpose, an extrapolation can be performed, for example as shown in FIG.

[0086] Figure 6 shows the water vapor concentration as a function of the distance between the sensor and the membrane under test. Based on these measurements, a function can be determined. By determining this function, conclusions can be drawn about the water vapor concentration on the surface of the object and in the environment.

Claims

1. A measuring device for measuring an intensive measurand, in particular the concentration of a substance released by a body by diffusion, or a temperature, comprising: At least one measurement chamber having at least one opening, the opening being capable of being placed on the object to be inspected. Equipped with at least three sensors for measuring the intensive measurands are arranged in the measurement chamber, the sensors being arranged at different distances from the object under test during measurement; An evaluation device is provided which receives the values measured by the sensors and determines a sum of the intensive measure from at least three of the measured values. A measuring device characterized by:

2. 2. The measuring device of claim 1, wherein the measuring chamber comprises at least two openings.

3. 3. The measuring device according to claim 1, wherein calculation rules are stored in the evaluation device, on the basis of which the evaluation device determines the sum value.

4. 4. The measuring device according to claim 1, wherein the calculation rules stored in the evaluation device weight the values measured by the sensors differently to determine the total value of the intensive measure.

5. 5. The measuring device according to claim 1, wherein the calculation rules stored in the evaluation device use a robust estimator when determining the sum value.

6. 6. The measuring device according to claim 1, wherein the total value is an estimated value that the evaluation device determines based on calculation rules, the calculation rules taking into account the time course of the total value.

7. 7. The measuring device according to claim 1, wherein a model function is stored in the evaluation device or in a downstream separate evaluation unit for an approximate simulation of the actual course of the intensive measured quantity to be determined.

8. 8. The measuring device according to claim 1, wherein the measuring chamber comprises at least one side wall, and the at least three sensors are arranged on the at least one side wall at different distances from the object to be inspected.

9. 8. The measuring device according to claim 1, wherein the measuring chamber comprises at least one side wall, and the at least three sensors are arranged spaced apart from the side wall in a central region of the measuring chamber at different distances from the object to be examined.

10. Measuring device according to any one of claims 1 to 9, characterized in that the measuring chamber has a circular cross section.

11. 11. The measuring device according to claim 1, wherein the at least three sensors are arranged in at least three rows, the at least three rows being arranged at different distances from the object to be inspected, and wherein at least one sensor is arranged per row.

12. Measuring device according to any one of claims 1 to 11, characterized in that the sensor measures the concentration of a substance emitted by the object by diffusion.

13. 13. The measuring device according to claim 12, characterized in that the sensor for measuring the concentration of a substance released by diffusion further measures the temperature and / or relative humidity, or in that at least three temperature sensors and / or sensors for measuring relative humidity are further provided for measuring the temperature and / or relative humidity, which are also positioned at different distances from the object to be inspected during measurement.

14. 14. The measuring device according to claim 13, characterized in that the evaluation device also receives the measured values of the temperature and / or relative humidity and determines a total temperature value and / or a total relative humidity value based on the measured values.

15. Measuring device according to any one of claims 13 to 14, characterized in that the temperature sensor and / or the sensor for relative humidity are also arranged on the side wall.

16. 1. A method for measuring an intensive measurand, in particular the concentration of a substance released by an object by diffusion, or a temperature, comprising: Mounting at least one measurement chamber having at least three sensors for measuring said intensive measurands on the object to be inspected, said measurement chamber having at least one opening mounted on said object to be inspected. It is characterized by the measurement chamber is mounted such that the sensor is positioned at different distances from the object under test during measurements; an evaluation device receives the values measured by the sensors, and the sum value of the intensive measure is determined by the evaluation device from the measurements; method.

17. 17. The method of claim 16, wherein a calculation rule for determining said total value is stored and said total value is determined based on the calculation rule.

18. 18. A method according to claim 16 or 17, characterized in that when determining the total value, the values measured by the sensors are weighted differently in the calculation rules.

19. 20. The method of claim 18, wherein the measurements of the sensors located closer to the object under inspection are weighted more highly.

20. Method according to any one of claims 16 to 19, characterized in that a robust estimator is used to determine the sum value.

21. 20. The method according to claim 16, wherein a model function is used for an approximate simulation of the actual course of the intensive measure to be determined.

22. 22. A method according to any one of claims 16 to 21, characterized in that it is possible to determine the value of the intensive measure for a particular distance from the surface that was not measured directly by a sensor.

23. 23. A method according to any one of claims 16 to 22, characterized in that the concentration of a substance released by a body by diffusion is measured as an intensive measure.

24. 21. The method of claim 20, further characterized in that the temperature and / or relative humidity are measured as intensive measurements at at least three points at different distances from the object.

25. 21. The method according to claim 16, further comprising determining the rate of diffusion of the measured intensive measurand c(z) from the gradient ∇c(z) of the corresponding measurand, analogously to Fick's law.

26. 26. The method of claim 25, wherein the intensive measure is the temperature and the diffusion rate is heat loss.

27. 26. The method of claim 25, wherein the intensive measure is a substance concentration and the diffusion rate is a substance amount per time and per area.

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