DE102013015033A1 - Flow measuring cell for the analysis of fluid media - Google Patents

Abstract

It was possible to create a flow-through measuring cell for the analysis of fluid media with as simple a means as possible, which can be adapted to a wide variety of application and measuring conditions for universal use and which can be easily cleaned for reusability. According to the invention, the flow-through measuring cell consists of a sandwich-like modular structure of a double-sided with an upper and a lower cover (5, 6, 10) liquid-tight sealable exchange and thus in its channel structure (2) variable flow body (1).

Description

The invention relates to a flow measuring cell for the analysis of fluid media, for example for blood tests, in order to characterize these media with regard to their chemical and physical properties. As physical properties, for example, the flowability (viscosity) or the deposition behavior of substances contained in the liquids could be investigated. For chemical and biochemical characterization, the composition of the fluid media and in particular the substances and compounds contained therein, such as DNA, RNA, proteins, molecules, etc., are determined, inter alia with the aim of field and on-site analysis in diagnostics Range as well as for rapid tests in drug therapy to gain results with high informative value.

Known potential applications are the pharmaceutical, chemical and food industries, but also medical practices and facilities. Such flow measuring cells not only provide qualitative but also quantitative information for the identification of the fluids. Especially for a therapy-accompanying online monitoring of drug administration, it is necessary to monitor whether the drug concentration in the range of action, the so-called "steady state" range, is located in order to initiate measures in case of a possible overdose. Even with reduced kidney or liver function monitoring the drug level is necessary because it can lead to life-threatening toxic side effects otherwise. It is also necessary to monitor levels of the drug in the blood when using immunosuppressants or chemotherapy.

For example, methotrexate (MTX), a drug for cancer and tumor therapy, must be compensated for by regular administration of leucovorin, otherwise severe bone marrow and mucosal damage may result. To monitor the decrease or increase in the MTX level to critical concentration, a blood sample is taken and analyzed every 5 to 6 hours after treatment ( JL Pauley et al .: Late-onset delayed excretion of methotrexate, Cancer Chemotherapy and Pharmacology 54, 2004, 146-152 ) This process could be automated by such flow cells for on-line monitoring of MTX in the blood.

Devices for detecting low-concentration substances are known per se. Due to the good sensitivity and specificity, especially in drug monitoring, high-pressure liquid and gas chromatography have become established as reference methods ( K. Dörner and R. Sommer: Therapeutic Drug Monitoring, Clinical Chemistry and Hematology, Thieme Verlag, 2006, 483-496 ), which however are very complex, so that these methods are only conditionally applicable for on-site analyzes or rapid tests and online monitoring.

To detect low-concentration substances, the interaction of the substance with a surface is realized so that an optical detection is possible. For example, the detection can be carried out via the surface-enhanced Raman effect (SERS), via fluorescence, via surface plasmon resonance or reflectometric interference. In addition, other optical / electromagnetic detection types (such as absorption, transmission, magnetic inductive or capacitive) are conceivable.

SERS has established itself as a powerful method, especially for substance investigations in analytical fields ( K. Kneipp et al .: Ultrasensitive Chemical Analysis by Raman Spectroscopy, Vol. 99. Chem. Rev., 1999, 2957-2975 ). The coupling of the SERS method with microfluidic applications in so-called lab-on-chip systems ( A. Maerz et al.: Droplet formation via flow-through microdevices in Raman and Surface Enhanced Raman spectroscopy concepts and applications, Lab on a Chip. 11, 2011, 3584-3592 ) is a current branch of research for the automated quantitative concentration determination with the potential to be used also in the area of drug monitoring.

So will in the US 2012/0107958 A1 presented an optical sensor for detecting chemical groups based on surface-enhanced Raman spectroscopy. The sensor includes a special surface substrate to effectively detect the analyte molecules. Here, gain factors of the signal are given by the 10 ¹² -10 ¹⁴ -fold, so that the theoretical possibility exists to detect single molecules. It is stated to achieve high structural specificity with high detection sensitivity. The US 2012/0107958 A1 discloses a fixed and directly into the glass with a depth of about 1.2 to 2 mm incorporated channel structure for flowing through the liquid to be analyzed and about 0.8 mm deep lying therein a surface substrate. The channel structure is filled with a pipette and then closed with a coverslip. The sensor is determined in its application to the analytical properties determined by this channel structure. Applications that require different flow conditions require other devices, whereby no universality in use is given and a variety of different sensor devices require a correspondingly high cost.

In DE 10 2010 053 749 A1 describes a device which detects biotic particles by means of Raman spectroscopy in an unspecified measuring cell, which is only used for the measurement when a sensor connected in front of the measuring cell registers biotic particles. Although this allows a minimized measurement effort in the measuring cell itself, but there is a risk that not registered by the sensor biotic particles are not detected. However, the upstream of the detection of said biotic particles measuring cell embodies in turn an increased effort and, as well as their applications, as stated, not explicitly disclosed.

DE 694 33 403 T2 shows a fluorescence cell for mainly chromatographic, but also for other capillary applications. Due to a fluorescent light collector, this measuring cell has the advantage of collecting a lot of fluorescent light and guiding it to the detector. However, due to its design, it is designed exclusively for capillary measurements, which also severely restricts its usability in analytics.

According to US 7,545,490 B1 There is a need for an inexpensive and easy to clean Raman measuring cell for monitoring a fluid. For this purpose, a measuring cell with a linearly prescribed channel structure incorporated into it and with an inlet and outlet connection for the fluid is presented. The measuring cell with the incorporated channel structure is sealed by means of a sealing rubber with the following glass pane and a lid and can be opened accordingly for cleaning the channel structure. The measuring cell is again limited to applications with these flow conditions due to the given channel structure.

In US 6,388,746 B1 a measuring cell for the sensitive detection of the fluorescence of molecules is presented, whose fixed channel, in which the measurement takes place, is extremely constricted to approximately the size of the focused laser spot. Thus, the direct determination of the concentration of the substance in the liquid medium without the use of internal or external standards is possible. Again, there is no universal use possible due to the special structure.

In US 2009/0214392 A1 presents a nano-fluidic measuring cell for SERS with a fixed channel, which can increase the reproducibility and sensitivity to metal nanoparticles based SERS measurement. The metal nanoparticles and the target molecules are formed by capillary forces into SERS-active clusters.

In US 2011/0294691 A1 discloses a SERS-based chip system in which nucleotide binding pairs can be detected. The chip system includes upper and lower electrodes with intervening dielectric layers containing microchannels and so-called microwells. The electrodes move the metal nanoparticles into the microwells. This increases the signal intensity of the SERS spectra. These microchannels are fixed and thus limited to appropriate applications.

Other so-called optofluidic chip-based measuring cells are known. For example, in ( White et al .: SERS-based detection in an optofluidic ring resonator platform, Optics Express. 15, 2007, 17433-17442 ) presented a ring resonator platform to limit the electromagnetic energy of the excitation radiation longitudinally through a microfluidic channel, with the advantage of allowing the complete cross section of the channel and thus the interaction of the excitation light with a larger number of particles, so that a concentration of approx. 400 pM Rhodamine 6G can be detected.

It is also described a SERS measuring cell, which is coupled with a microarray chip and colloids and used for the detection of bacteria, so that there is only a low risk of contamination ( M. Knauer et al .: A flow-through microarray cell for the on-line SERS detection of antibody-captured E.coli bacteria, Analytical and Bioanalytical Chemistry 402, 2012, 2663-2667 ).

Also known is a measuring cell with integrated temperature and flow rate control ( B. Ren et al .: Spectroelectrochemical flow cell with temperature control for investigation of electrocatalytic systems with surface-enhanced Raman spectroscopy, Faraday Discussions 140, 2008, 155-165 ) to allow SERS detection as a function of the temperature and flow rate of the fluid.

An electrochemical measuring cell was also presented ( H. Luo and MJ Weaver: A versatile surface Raman spectroelectrochemical flow cell: applications to chemisorbate kinetics, Journal of Electroanalytical Chemistry 501, 2001, 141-150 ) which uses SERS to show adsorption and desorption effects of the electrodes.

A measuring cell with an effective capacity of 2.5 μl was used by Kennedy et al. represented ( BJ Kennedy et al .: Development of a cascade flow cell for dynamic aqueous phase detection using modified SERS substrates, Analytical Chemistry 69, 1997, 4708-4715 ). The measuring cell is used in liquid chromatography or in the flow Injection analysis (FIA) application and contains a SERS substrate to allow SERS detection of aromatic compounds in an aqueous environment. It shows the basic possibility that SERS can also be suitable for FIA applications.

Also by Gouveia et al. ( Gouveia et al., 1994 ) describes a FIA measuring cell for SERS analysis using a silver-coated glass-carbon electrode as SERS-active substrate ( VJP Gouveia et al .: A NEW SPECTRO-ELECTROCHEMICAL CELL FOR FLOW-INJECTION ANALYSIS AND ITS APPLICATION TO THE DETERMINATION OF FE (II) DOWN TO THE FEMTOMOL LEVEL BY SURFACE-ENHANCED RESONANCE RAMAN-SCATTERING (SERRS), Journal of Electroanalytical Chemistry 371 , 1994, 37-42 ). Here, too, the FIA method with the SERS detection of several adsorbants on the electrode is shown as advantageous.

In summary, it should be noted that a multiplicity of flow measuring cells are known, wherein these are designed and provided for their specific and application-specific uses both by their structure, in particular their flow system for the fluid to be investigated, and by the detection system used. In addition, uses therefore also require the provision and use of other measuring devices.

A disadvantage of the previously mentioned measuring cells is that although products with defined detection properties for certain applications arise, but these cells can not be readily used multivalent for different detection methods.

The invention is therefore based on the object to create a flow-through cell for the analysis of fluid media with the simplest possible means, which aufwandgering for universal use adaptable to a variety of application and measurement conditions and is easy to clean for reusability.

This object is achieved in a flow measuring cell for the analysis of fluid media, in particular for the detection of substances contained therein, wherein the fluid medium, the flow-through measuring cell preferably flows through inlet and outlet nozzles in a defined liquid-tight sealable channel structure and thereby an optical or electromagnetic Radiation of detection methods, such. B. surface-enhanced Raman spectroscopy (SERS), fluorescence, surface plasmon resonance (SPR), reflectometric interference (RIFS), according to the invention, characterized in that the flow-through measuring cell of a sandwich-like modular construction of a double-sided with a upper and a lower cover liquid-tight sealable exchange and thus changeable in its channel structure flow body consists.

Advantageously, the flow-through measuring cell essentially already consist of said modular construction of the flow passage body having the channel structure with its lower and upper cover, wherein the flow body for the automatic inlet and outlet of the fluid medium to be analyzed preferably each directly directly one permanently connected to this - And effluent nozzle for the fluid to be analyzed has.

It may also be advantageous if the flow body is accommodated for the purpose of interchangeability or cleaning in a frame with inlet and outlet for the fluid to be analyzed, the connections between the flow body and each of the inlet and outlet nozzle of the frame liquid-tight and are designed separable.

Thus, the flow body of the flow cell can be exchanged with its channel structure and in each case in a low and fast way by other flow body with differently shaped channel system (other channel shapes, gradients and geometries, for example, channels with zones of different flow rate of the fluid medium for specific or different Detection methods).

The flow body is liquid-tightly closed by an upper and a lower cover, one of these covers, in particular on the upper side of the flow body as a window for the detection method to be used (for example, an optical window for SERS detection) and the opposite cover completely or partially as Surface substrate for the applied detection method for the investigation of the fluid medium may be formed.

In this way, not only the flow body with its channel system is modular exchangeable (and thus individually configurable and changeable), but also the window and the surface substrate for the said detection method, whereby the flow cell can be adapted application-specific and universal to a variety of application conditions regardless of whether the flow measuring cell, as already described by the flow body with its said covers is formed or whether this is located in a frame. Thus, for example, the surface substrate in combination with a borosilicate glass or other glass with the required optical properties can be adapted, which are due to the modular design of the flow measuring cell to the immediate part. Furthermore, the flow cell can be prepared for other than optical detection methods by the exchange of the surface substrate and the other cover. In this case, even those covers can be selected, which can interact with their material or corresponding surface coating during the passage of the fluid medium with this, to perform special investigations.

The cover of the flow body designed as a window does not necessarily have to have in its geometry a pass-shaped image of the channel structure of the flow body, since the flow body itself forms the channel structure for the passage of the fluid medium and its evaluation.

As a result of the separable covers of the flow body both the channel structure for the fluid medium and the window and the surface substrate for the detection system are not only universally interchangeable, but also easily accessible and easy to clean especially for their reusability. As a result of the uncomplicated and quick cleaning or replacement possibility, after passing through a medium for further use contaminations, carry-over or memory effects, which may well occur in known devices, effectively avoided.

With the proposed flow cell, it is not necessary to change the entire flow and sensor system for specific operating conditions, but only the modular structure of the flow body and its covers. With this adaptability, the flow cell would be prepared for the future even with the adaptability of the flow body covers for new detection methods.

In the subclaims further advantageous embodiments of the flow measuring cell are mentioned.

The invention will be explained below with reference to exemplary embodiments illustrated in the drawing.

Show it:

1 : Representation of a modular flowmeter according to the invention for the analysis of fluid media in an exploded view

2 : Sectional view of the flow cell according to 1

3 : Schematic representation of the flow cell in explosive view with recognizable channel structure of the flow body

4 : Schematic representation of the flow measuring cell in explosive view with symbolized exchangeability of the flow body for different channel structures

In 1 an embodiment of the proposed flow measuring cell for the detection of substances in a fluid medium is shown. The flow cell consists of a flow body 1 with a channel structure 2 for the fluid medium not explicitly shown. The flow body 1 is in a recording bed 3 a downwardly and upwardly open body 4 as a framework included in this interchangeable. Covered is the flow body 1 liquid-tight through a glass plate 5 , where the channel structure 2 made of an elastic material, such as silicone, and is in positive and non-positive support of the glass plate 5 on this elastic channel structure 2 a liquid-tight cover results. The glass plate 5 is for an optical detection radiation, for example, for Raman spectroscopy (SERS), which with the necessary components for reasons of clarity also not in 1 is shown, permeable. The flow body can be loosely attached 1 with the glass plate 5 by means of a cover plate 6 , their screws 7 in threaded holes 8th of the basic body 4 to grab. Two screws 7a each grip through a hole 25 of the basic body 4 in a corresponding threaded hole 12 a mounting flange 11 , By loosening the screws 7 and removers of the cover plate 6 and the glass plate 5 can the flow body 1 from the recording bed 3 of the basic body 4 be removed, for example, for the purpose of its purification or even the exchange against a flow body with a different channel structure (see schematic representation of 4 ). A central hole 9 in the cover plate 6 works in conjunction with the glass plate 5 as a window for the unillustrated radiation of the detection method (for example said Raman spectroscopy). Covered from below is the flow body 1 with the channel structure 2 through a surface substrate 10 with a surface active for the aforesaid detection method. Again, results from the, as described above, elastic channel structure 2 with non-positive and positive support of the surface substrate 10 a liquid-tight cover of the channel structure. The surface substrate 10 gets on the body 4 through the mounting flange 11 with the two threaded holes 12 through the two screws 7a over the holes 25 releasably secured and is thus (like the Flow body 1 ) from the main body 4 removable or exchangeable. Thus, the entire modular flow measuring cell is by a few simple steps (only by fastening / loosening the screws 7 . 7a ) Quick and easy to assemble, disassemble and convert. Instead of the screws 7 . 7a with the threaded holes 8th . 12 were also other releasable fasteners, such as locking elements, snap-in or bayonet locks, etc. (not shown in the drawing) conceivable.

About an inlet port 13 and an outlet port 14 , each with ferrule, each one in one with the channel structure 2 of the flow body 1 related inflow opening 15 or discharge opening 16 of the basic body 4 the flow of the fluid to be tested in the measuring cell is ensured by passing it through the inlet port 13 , the canal structure 2 and the outlet port 14 is preferably passed through a pump, not shown. When flowing through the channel structure 2 of the flow body 1 is the fluid medium through the window (central bore 9 in the cover plate 6 in connection with the glass plate 5 ) exposed to the predetermined radiation by the detection method, which subsequently by the interaction with the surface substrate 10 can be analyzed and evaluated, whereby interactions by the exciting optical radiation, which are not directly related to the surface can occur (such as no surface-enhanced Raman scattering (SERS) of the fluid, but the Raman scattering in the classical sense, or surface-substrate-independent and fluid-generated fluorescence, which can be used for evaluation and analysis.

The illustrated embodiment in 1 is especially suitable for microscopic examinations. The flow measuring cell is passed through the cover plate 6 defined in their size.

In 1 is that the channel structure 2 having flow body 1 for inclusion in the up and down open body 4 shown as a frame. It would also be conceivable that the flow body 1 with its upper cover through the glass plate 5 and the cover plate 6 and with its lower cover by the surface substrate already forms an independent flow measuring cell and in each case has a fixedly connected to this inlet and outlet connection for the fluid to be analyzed (not shown in the drawing).

In 2 is the in 1 as an explosive view shown flow measuring cell 9 shown in assembled sectional view. The fluid medium to be examined (by arrows 17 symbolized) with molecules contained therein and to be analyzed 18 is via an inner channel 19 the inlet port 13 and the inflow opening 15 through the channel structure 2 of the flow body 1 pumped (pump not shown for clarity) and can through the drain opening 16 and an inner channel 20 the outlet port 14 drain again from the measuring cell. When flowing through the channel structure 2 wet the molecules 18 the surface substrate 10 and can for their analytical evaluation, for example via an illustrated monochromatic excitation light 21 be stimulated, with molecule-specific interactions with the active surface of the surface substrate 10 (SERS detection method). An emerging emission light 22 is used for analysis and specific detection of the molecules 18 used.

3 shows as an example of other uses of the proposed flow measuring cell whose schematic structure for analysis of the fluid medium in the channel structure 2 of the flow body 1 , Here are changes in layer thickness caused by binding of the molecules not explicitly shown (see. Molecules 18 in 2 ) of the fluid medium on the surface substrate 10 placed catcher molecules 23 be detected by reflectometric interference. The modular structure of the flow cell becomes a corresponding surface substrate 10 used or replaced. For the schematic structure are in 3 the cover plate 6 and the glass plate 5 (see. 1 ) as an optical window 24 summarized.

In 4 should the multivalent applicability of flow meter according to the invention by the interchangeability of the flow body 1 with its channel structure 2 be clarified. The cover plate 6 and the glass plate 5 are (as in 3 ) as an optical window 24 above the flow body 1 summarized. Under the flow body 1 is the here not unspecified and to be selected for the detection method to be used surface substrate 10 , Instead of the flow body shown in the middle 1 with its channel structure 2 For example, in the modular structure of the flow measuring cell (when it is being retrofitted or retrofitted), a flow body shown on the left can be seen 1a with a channel structure 2a or also a flow body shown to the right 1b with a channel structure 2 B be used. For retrofitting, the flow cell will be in accordance with the explosive view in 1 disassembled and with the corresponding inserted flow body 1 . 1a or 1b remounted. In this way, the flow measuring cell can be universally used in a simple manner and in the shortest time to be equipped or retrofitted to a variety of channel structures to realize application-specific flow characteristics in the measuring cell. So would be special channel structures, for example, with multiple inflows and outflows and diverse design of the channel profile with parallel and mixed structures, zones of different channel width and flow rate and other channel courses realized.

LIST OF REFERENCE NUMBERS

1, 1a 1b

Flow body

2, 2a, 2b

channel structure

3

receiving bed

4

Basic body (frame)

5

glass plate

6

cover plate

7, 7a

screw

8, 12

threaded hole

9

central bore

10

surface substrate

11

mounting flange

13

inlet port

14

outlet port

15

inflow opening

16

drain opening

17

Arrows (fluid medium)

18

molecule

19, 20

internal channel

21

excitation light

22

emission light

23

capture molecule

24

optical window

25

drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2012/0107958 A1 [0007, 0007]
• DE 102010053749 A1 [0008]
• DE 69433403 T2 [0009]
• US 7545490 B1 [0010]
• US 6388746 B1 [0011]
• US 2009/0214392 A1 [0012]
• US 2011/0294691 A1 [0013]

Cited non-patent literature

• JL Pauley et al .: Late-onset delayed excretion of methotrexate, Cancer Chemotherapy and Pharmacology 54, 2004, 146-152 [0003]
• K. Dörner and R. Sommer: Therapeutic Drug Monitoring, Clinical Chemistry and Hematology, Thieme Verlag, 2006, 483-496 [0004]
• K. Kneipp et al .: Ultrasensitive Chemical Analysis by Raman Spectroscopy, Vol. 99. Chem. Rev., 1999, 2957-2975 [0006]
• A. Maerz et al.: Droplet formation via flow-through microdevices in Raman and Surface Enhanced Raman spectroscopy concepts and applications, Lab on a Chip. 11, 2011, 3584-3592 [0006]
• White et al .: SERS-based detection in an optofluidic ring resonator platform, Optics Express. 15, 2007, 17433-17442 [0014]
• M. Knauer et al .: A flow-through microarray cell for the on-line SERS detection of antibody-captured E.coli bacteria, Analytical and Bioanalytical Chemistry 402, 2012, 2663-2667 [0015]
• B. Ren et al .: Spectroelectrochemical flow cell with temperature control for investigation of electrocatalytic systems with surface-enhanced Raman spectroscopy, Faraday Discussions 140, 2008, 155-165. [0016]
• H. Luo and MJ Weaver: A versatile surface Raman spectroelectrochemical flow cell: applications to chemisorbate kinetics, Journal of Electroanalytical Chemistry 501, 2001, 141-150 [0017]
• BJ Kennedy et al .: Development of a cascade flow cell for dynamic aqueous phase detection using modified SERS substrates, Analytical Chemistry 69, 1997, 4708-4715 [0018]
• Gouveia et al., 1994 [0019]
• VJP Gouveia et al .: A NEW SPECTRO-ELECTROCHEMICAL CELL FOR FLOW-INJECTION ANALYSIS AND ITS APPLICATION TO THE DETERMINATION OF FE (II) DOWN TO THE FEMTOMOL LEVEL BY SURFACE-ENHANCED RESONANCE RAMAN-SCATTERING (SERRS), Journal of Electroanalytical Chemistry 371 , 1994, 37-42 [0019]

Claims (9)

Flow measuring cell for the analysis of fluid media, in particular for the detection of substances contained therein, wherein the fluid medium flows through the flow measuring cell preferably via inlet and outlet nozzles in a defined liquid-tight sealable channel structure and thereby optical or electromagnetic radiation of detection methods, such as For example, (surface-enhanced) Raman spectroscopy (SERS), fluorescence, surface plasmon resonance (SPR), reflectometric interference (RIFS), is exposed, characterized in that the flow-through measuring cell consists of a sandwich-type modular construction of a double-sided with an upper as well a lower cover ( 5 . 6 . 24 . 10 ) liquid-tight sealable exchange and thus in its channel structure ( 2 . 2a . 2 B ) variable flow body ( 1 . 1a . 1b ) consists. Flow measuring cell according to claim 1, characterized in that one of the covers of the double-sided liquid-tight sealable flow body ( 1 . 1a . 1b ) completely or partially as a surface substrate ( 10 ) is designed for the applied detection method for the examination of the fluid medium. Flow measuring cell according to claim 1, characterized in that the modular structure of the channel structure ( 2 . 2a . 2 B ) having flow body ( 1 . 1a . 1b ) with its lower and upper cover ( 5 . 6 . 24 . 10 ) already forms an independent flow measuring cell, wherein the flow body ( 1 . 1a . 1b ) directly each having a firmly connected to this inlet and outlet connection for the fluid to be analyzed. Flow measuring cell according to claim 1, characterized in that the flow body ( 1 . 1a . 1b ) for the purpose of interchangeability in a framework ( 4 ) with inlet and outlet connection ( 13 . 14 . 15 . 16 ) is received for the fluid medium to be analyzed, wherein the connections between the flow body ( 1 . 1a . 1b ) and in each case the inlet and outlet connection ( 13 . 14 . 15 . 16 ) of the frame ( 4 ) are designed separable. Flow measuring cell according to claim 2, characterized in that the surface substrate ( 10 ) formed cover is provided with a coating which can interact with the same chemically and / or physically for the analysis of the fluid medium. Flow measuring cell according to one or more of claims 1 to 5, characterized in that at least one of the covers a liquid-tight window ( 5 . 6 . 24 ) for the radiation of the applied detection method. Flow measuring cell according to claim 6, characterized in that the window ( 5 . 6 . 24 ) is provided with a coating which can chemically and / or physically interact with it for the analysis of the fluid medium. Flow measuring cell according to claim 6, characterized in that the window ( 5 . 6 . 24 ) for the purpose of changing the window effect and / or the interaction with the fluid medium, in particular with regard to the applied detection method, in the cover ( 5 . 6 . 24 ) is designed exchangeable. Flow measuring cell according to claim 2, characterized in that the surface substrate ( 10 ) is formed in one of the covers of the flow body as an exchangeable partial surface substrate.

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