DE102014108349A1 - Measuring arrangement with a carrier element and a micromechanical sensor - Google Patents

Abstract

Comprising a measuring arrangement
a) a support element (14) with a longitudinal axis (A) on or on which a micromechanical sensor (1) for determining a process variable of a gaseous or liquid fluid is arranged, and
b) the micromechanical sensor (1) for determining a process variable of a gaseous or liquid fluid having a sensor base body (2) which has a fluid channel (5) which extends within the sensor (1) from a fluid inlet to a fluid outlet, and
c) wherein the carrier element (14) has a fluid supply channel (15) for supplying the fluid to the sensor (1) and a Fluidabführkanal (16) for discharging the fluid from the sensor (1),
characterized in that the Fluidzuführkanal (15) of the support member (14) at least partially a Parylenebeschichtung (10) which extends over the fluid channel (5) of the sensor (1) into the Fluidabführkanal (16) of the support member (14),
and a method of applying a parylene layer to a measuring device.

Description

The present invention relates to a measuring arrangement comprising a carrier element and a micromechanical sensor according to the preamble of claim 1 and a method for applying a polymer layer in a measuring arrangement.

A generic measuring arrangement of a carrier element with a micromechanical sensor is in the PCT / EP2013 / 071617 and in the DE 10 2013 017 317 A1 described. Within the carrier element, a tube made of steel or plastic is arranged for a better arrangement of the micromechanical sensor. In the case of the measurement of aggressive media, however, the medium-contacting material of the sensor and / or the carrier element can be attacked.

It is therefore an object of the present invention to provide improved protection of the sensor and / or the carrier element and / or the connection of these two elements

The present invention solves this problem by a measuring arrangement having the features of claim 1 and by a method having the features of claim 8.

A measuring arrangement according to the invention comprises a carrier element with a longitudinal axis A on or on which a micromechanical sensor for determining a process variable of a gaseous or liquid fluid is arranged. The measuring arrangement according to the invention also comprises said micromechanical sensor for determining a process variable of a gaseous or liquid fluid having a sensor base body which has a fluid channel which extends within the sensor from a fluid inlet to a fluid outlet. The carrier element has a fluid supply channel for supplying the fluid to the sensor and a Fluidabführkanal for discharging the fluid from the sensor.

According to the invention, the fluid feed channel of the carrier element has a parylene coating, which extends over the fluid channel of the sensor into the fluid discharge channel of the carrier element.

The micromechanical sensor can be designed as a flow meter in a preferred embodiment. In the field of flowmeters so-called liner made of plastic are often used to protect a support tube. However, the usual liner materials are casting resins or insertion elements made of rubber or the like. Due to the small nominal diameter of the fluid channel of a micromechanical sensor, however, all or at least the predominant part of the liner materials are unsuitable for use in micromechanical sensors, in particular in MEMS sensors. They lead to a large reduction in the nominal size, which causes a large measurement inaccuracy of the sensor. By contrast, a parylene coating allows effective protection of the fluid channel in the carrier element and in the micromechanical sensor. The parylene coating can be realized in layer thicknesses of 10 μm or less. Since the deposition is carried out from the gas phase, a relatively uniform layer thickness of the coating over the entire fluid channel of the measuring arrangement can be achieved.

Advantageous embodiments of the invention are the subject of the dependent claims.

It is advantageous if the parylene coating has a layer thickness of less than 5% of the nominal diameter of the inner diameter of the fluid channel of the micromechanical sensor, preferably less than 2% of the nominal diameter of the inner diameter of the fluid channel. If this nominal size jump is uniform over the course of the fluid channel of the sensor, then this measurement span can be taken into account in the evaluation and computationally compensated.

It is advantageous if the parylene coating has a tensile strength greater than 5000 psi, preferably greater than 7000 psi ASTM D882 having. As a result, the connection between the sensor and the carrier element is additionally improved.

The moisture permeability of the parylene coating is advantageously less than 0.3 (g · mm) / (m ² · 24 h), preferably less than 0.25 (g · mm) / (m ² · 24 h) at 37 ° C and 90% relative humidity, according to ASTM F1249 , The low diffusion reduces the risk of diffusion and peeling of the coating in the case of aqueous solutions and moist gases.

It is advantageous if the parylene coating consists essentially of HT-parylene. This monofluorinated variant of the parylenes has a very low coefficient of friction compared to other parylene compounds. This reduces the tendency for deposits to adhere to the coated surface.

The carrier element can advantageously for mechanical connection of the Fluidzuführkanals and / or Fluidabführkanals of the support member having the fluid channel of the sensor has a bonding layer which extends over a portion of a surface of the support member and over a portion of a surface of the sensor. This attachment layer is not within the Fluid channel but arranged on an outer surface of the sensor facing the carrier element and connects the carrier element with the sensor.

The bonding layer may be an adhesive, a polyfluorinated plastic, in particular Halar, and / or a metal solder, in particular a gold, silver and / or tin solder. Connection elements between the sensor and the carrier element, such as e.g. Metal tubes can be provided. However, the sensor can also be connected in a kind of floating adaptation exclusively by the solder, the adhesive or the halar with the support element without additional connection elements. In this case, manufacturing tolerances can be compensated by the solder as a less rigid connection compared to the connection elements. Possible occurring dead volumes in the region of the bonding layer are reduced or completely prevented by the Parylenebeschichtung.

In a method according to the invention for applying a parylene layer in a measuring arrangement according to claim 1, the parylene deposition is effected by supplying a gaseous starting material, a parylene layer forming on the surface of the measuring arrangement. In the gas phase, reactive monomers and / or dimers are present which condense and polymerize on contact with the surface of the measuring arrangement. Unlike conventional casting resins, this process also makes it possible to line fluid channels having very small nominal diameters, e.g. of 100-900 μm channel diameter, without blocking the channel or causing a significant nominal size jump.

Further advantageous embodiments of the invention will also be described below.

If a solder connection is selected as the attachment layer, this can advantageously be produced by melting a solder wire or particularly preferably a structured solder foil or a solder coating deposited electrochemically or by vapor deposition.

At least one material component of the solder joint is particularly advantageously a precious metal, in particular gold, and / or tin. Also included in this definition are alloys, e.g. a gold / tin alloy.

The carrier element and / or the optional connection element may advantageously consist of metal, preferably of stainless steel, particularly preferably of stainless steel of the grade PH 17-4 or zirconium. Especially the latter special steel grade has a favorable thermal expansion coefficient compared to the material of the micromechanical sensor. Zirconium is particularly preferred because it is even more corrosion resistant than the aforementioned stainless steel grade and also has a low thermal expansion coefficient to other metals.

The thermal expansion coefficient of the material of the carrier element may advantageously be less than 5 times, preferably less than 4 times, the coefficient of thermal expansion of the material of the sensor. This creates a pressure-stable and temperature-resistant connection between carrier element and sensor.

For additional stabilization, it is advantageous if further cohesive connections are arranged between the sensor and the carrier element. These cohesive connections may in particular be solder connections or adhesive connections.

It is particularly advantageous if the aforementioned cohesive connections are distributed as uniformly as possible in the region between the sensor and the carrier element. Therefore, it is advantageous if the surface of the sensor facing the carrier element can be divided into at least three identically dimensioned sensor sections, wherein at least two of the three sensor sections have at least one of the integral connections.

An inventive method for applying a polymer layer in a measuring arrangement, in particular a measuring arrangement according to claim 1, is carried out by supplying a gaseous starting material and wherein a polymer layer is deposited by polymerization of the gaseous starting material on the surface of the measuring arrangement.

By virtue of the method according to the invention, it is possible to line fluid channels with very small nominal widths and thus protect the material of the measuring arrangement from the measuring medium.

The measuring arrangement is in particular a flow meter and the polymer is preferably parylene. However, if other polymers can be deposited with a small layer thickness from the gas phase and correspondingly have material-protecting properties, these compounds are also covered by the subject matter of the invention.

In a particularly advantageous manner, an existing in the measuring arrangement fluid-conducting channel in the application of the polymer layer serve as a reaction chamber.

The invention will be explained in more detail with reference to the following drawings. Show it:

1 : Representation of a first measuring arrangement with a Parylenebeschichtung as inner lining;

2 : schematic representation of a partial section of the measuring arrangement; and

3 : Representation of a second measuring arrangement with a Parylenebeschichtung as inner lining.

In the 1 . 2 and 3 illustrated measuring arrangements are preferably used in measuring devices of process and automation technology.

The present invention relates to the lining of the fluid channel of a sensor and an extended fluid channel extending through a support member and the sensor attached thereto. The sensor is described in the following embodiments as a micromechanical sensor.

The base area of a preferred micromechanical sensor may, in its largest dimensioning, preferably correspond to the maximum base area of a wafer. The base area is to be understood as the area with which the sensor can be connected to the carrier element. However, the micromechanical sensor can also be made substantially smaller and, e.g. have a dimensioning in the range of a few millimeters.

Particularly preferably, at least one edge length of the sensor is less than or equal to 10 cm. Most preferably, all edge lengths of the sensor are less than or equal to 10 cm.

1 shows a first embodiment of a sensor 1 , which is formed in the present embodiment as a sensor for a Coriolis mass flowmeter in micro-mechanical design (MEMS - micro-electro-mechanical system). The sensor 1 includes a sensor body 2 formed of ceramic or glass and a surface having a first connection opening 3 and a second connection opening 4 , each comprising a diameter of about 1mm has. The sensor body 2 is cuboid and has a first and a second square side surface, each typically about 1 cm ^{2 are} large. The first and the second connection opening 3 . 4 are on a first side surface of the sensor body 2 arranged and lead to a flow-through volume, which is arranged in the interior of the sensor body and is delimited by means of a metal body, in particular a metal tube against the sensor body. The connection openings 3 and 4 open into a fluid channel 5 passing through the micromechanical sensor 1 extends.

1 also shows a carrier element 14 with a longitudinal axis A, on which a sensor for determining a process variable of a gaseous or liquid fluid can be arranged. The carrier element 14 has a fluid channel, which in the present example in a Fluidzuführkanal 15 and a fluid discharge channel 16 divided to supply and discharge of a fluid to the sensor. However, other support element sensor constructions are also possible, for example a pressure sensor in which the fluid supply and removal can be combined in one channel.

In the arrangement of 1 The sensor can also be used in the form of a Coriolis flowmeter for measuring the viscosity of the fluid. However, the sensor does not necessarily have to be designed as a Coriolis flowmeter. The type of sensor depends on the process variable to be determined.

This process variable may preferably be the density, the viscosity, the composition of matter, the temperature, pH, the conductivity, the particle content, the volume flow rate, the mass flow rate and / or the flow rate of a fluid.

The fluid supply channel has in the in 1 illustrated embodiment, a first channel segment 17 which is substantially parallel to the longitudinal axis A of the carrier element 14 runs. This duct segment can be connected terminally to a process connection of a pipeline. The fluid supply channel also has a second channel segment 18 into which the first channel segment 17 empties. This second channel segment 18 is in the present embodiment at an angle of 90 ° to the longitudinal axis in the carrier element 14 arranged. Here is the diameter of the first channel segment 17 larger, preferably at least twice as large as the diameter of the second channel segment 18 , The second channel segment 18 has a diameter expansion 19 for receiving a termination element 21 on. As a result, no nominal displacement within the second channel segment takes place after insertion of the connecting element 18 , Through the second channel segment 18 For example, the fluid can be led out of the carrier element radially to the axis.

In 1 the entire fluid flow is from a carrier element 14 over the second channel segment 18 through the micromechanical sensor 1 directed. However, the channel segment can 18 also be designed only as a bypass, while another fluid flow, in particular the main flow through a central channel 20 in the carrier element 14 to be led. This variant is in 3 shown.

The carrier element 14 also has the Fluidabführkanal 16 as part of the fluid channel, which is substantially identical to the Fluidzuführkanal 15 is constructed. Between the Fluidabführkanal and the Fluidzuführkanal in the case of a bypass optionally a channel connecting segment 20 be arranged, which in the support element 14 is arranged parallel to the longitudinal axis A and the fluid supply channel and the Fluidabführkanal interconnected.

The fluid supply channel 15 and the Fluidabführkanal 16 of the carrier element 14 are, as well as the fluid channel 5 of the sensor 1 , with a parylene layer 10 lined.

As already discussed, not all of the fluid flow through the sensor need be directed, but only a portion of the fluid. The nominal diameter of the channel connection segment has a smaller diameter, preferably at least twice the diameter of the first channel segment 17 ,

Microelectromechanical sensors, as can be used in the present example, are known per se. The sensors used in the present example can be embodied as Coriolis flowmeters, magnetic-inductive flowmeters, thermal flowmeters, pressure gauges, viscometers, spectroscopic gauges, ultrasonic gauges, especially ultrasonic flowmeters, density meters, and process variables such as viscosity, density, pressure, composition of matter , Temperature, viscosity, the pH, the conductivity, the particle content and / or possibly also determined flow. For the purposes of the present invention, sensors also include chromatographic analyzers (LC or GC analyzers). These are also feasible in micro-electro-mechanical design.

The microelectromechanical sensor is preferably made of a glass or silicon material. Typically, the thermal expansion coefficient of these materials is about 3 x 10 ^-6 K ^-1 . Alternatively, sensors made of ceramic materials or metal in the context of the present invention can be used for this purpose.

The optional connection elements 21 are either formed as separate components in the form of tubes or formed integrally. They are preferably made of stainless steel - preferably the type PH 17-4. Likewise, there is the carrier element 14 made of stainless steel, more preferably of the grade PH 17-4 or zirconium. Other materials, such as plastic materials, however, are also conceivable. Especially with particularly hot or cold fluids, however, it is advantageous if the coefficient of thermal expansion of the material of the sensor and the connection element do not deviate from each other by more than 5 times. Otherwise, leaks can occur at higher pressures or even peel off the sensor. Stainless steel of grade PH 17-4 meets these requirements with respect to a silicon material and / or glass material (incl. Borosilicate). If the connection elements are formed integrally with the carrier element, the material of the carrier element should naturally correspond to the material of the connection elements. However, if the connection elements 21 as separate components in the carrier element 14 are provided, the material of the support member may preferably be selected from a less expensive material, such as grade 316 L stainless steel. Alternatively, other material, in particular titanium, aluminum, zirconium, tantalum, silicon or conductive ceramic material for the support element and / or the connection element can be used.

Additionally or alternatively to a metallic bonding layer 30 can also be provided as a bonding layer, a plastic layer. This may preferably be a copolymer.

In a particular embodiment variant, the connection layer exists 30 made of a plastic material selected from the following materials: PE, PEEK, PFA, PTFE, PBT and / or PEK. Here, however, in the case of the production of a galvanic coating, first an electrically conductive layer in the form of sputtering, metallization or vapor deposition must be applied.

Additionally or alternatively, it is also possible to use thermally conductive materials which have the thermal conductivity of the metallic bonding layer 30 increase, in which these bonding layer are integrated to allow a thermal contact between the support member and the sensor.

Additionally or alternatively, magnetic substances can also be incorporated into the plastic in order to enable the magnetic contact between sensor and carrier element. Corresponding magnetic substances may e.g. Be particles of magnetic ironstone.

Also, metallic elements, such as tracks, which improve the electrical conductivity can be included in the metallic bonding layer.

Between the carrier element and the connecting element and the carrier element and the sensor can also advantageously a pre-seal in the form of a membrane structure or a sealing lip may be arranged so that the solder joint is mechanically or chemically not excessively stressed.

If an aforementioned solder joint is created, it is advisable to previously treat the surfaces to be joined in order to allow a better adhesion. This may be done chemically by etching or by corona blasting or lasers or by abrasive methods, such as laser cutting. Sandblasting. The treated surfaces can then be better wetted by the solder. In addition, the adhesive strength of an adhesive bond and / or halo compound is improved. In order to wet the solder, the surface can be provided with a gold layer (electroplating, vapor deposition or sputtering). This is preferably done both on the side of the support member and on the side of the sensor.

The connection elements 21 allow in particular a fluidic connection between micromechanical sensor 1 and the carrier element 14 , However, especially at higher pressures, an additional mechanical connection of the microelectromechanical sensor is recommended 1 ,

The mechanical connection of the micromechanical sensor 1 , in particular of the microelectromechanical sensor, takes place in the exemplary embodiment of FIG 1 by means of a solder connection. This solder joint can be in the form of solder wires 38 and / or solder rings 39 on the carrier element 32 be upset. Through the solder rings 39 becomes a mechanical and at the same time pressure-stable and medium-tight connection of the connecting elements 21 with the carrier element 14 reached.

The connection between the microelectromechanical sensor and the carrier element may alternatively or in addition to a solder connection also be effected by an adhesive system, e.g. done by means of an epoxy resin. However, the solder joint is particularly stable against acids and alkalis.

In addition to the solder rings 39 are also solder wires on the carrier element 14 applied, which is a direct connection with the micromechanical sensor 1 enable.

As the solder material, a noble metal, e.g. Silver or gold or alloys thereof. For example, it is also possible to use eutectic mixtures of silver or gold and tin. The shrinkage of these materials is preferably less than 1 vol.%.

Alternatively or in addition to the solder rings and soldering wires, structured metal foils, in particular gold and / or tin foils, and / or a layer or layers deposited electrochemically or by vapor deposition, in particular a gold layer, can also ensure a secure connection. The solder can also be applied by means of a template on the substrate.

The solder material can be deposited on the carrier element by electrochemical deposition 14 or the sensor 1 respectively. This allows a more targeted application of the layer as a part of the surface of the support element 32 be masked. This guarantees a defined height of the solder and thus a defined volume of the solder.

As an alternative to the gold material, it is also possible to use tin material or alloys of both materials for the formation of the solder joints. Both gold and tin have good chemical resistance to most fluids. The shrinkage of these materials is preferably less than 1 vol.%.

It is advantageous if the solder layer is less than 1/5 mm, preferably less than 1/10 mm.

An electrochemical deposition of a metallic layer can take place by means of a galvanic deposition.

Alternatively, a multilayer electrochemical deposition can take place, wherein the gold layer and / or tin layer is only the uppermost layer towards the sensor.

In the case of a galvanic deposition of a metallic bonding layer on the sensor, the support element and / or the optional connection elements can be used to improve the deposition rate and the adhesion of a conductive paint, preferably a silver or graphite conductive paint.

Analogous to the connection between the carrier element 14 and one of the connection elements 21 can also be a connection between the microelectromechanical sensor 1 and one of the connection elements 21 be achieved.

Especially because of their mechanical stability is a uniform metallic bonding layer, which is different from the support element 14 over the connection element 21 to the microelectromechanical sensor 1 extends.

A preferred layer thickness of the bonding layer is less than 1 mm, preferably less than 200 μm and particularly preferably less than 100 μm. A particularly preferred layer thickness of the mechanical bonding layer is in the range between 100 nm and 100 μm.

The thus created connection of a sensor, which is designed for example in micro-electro-mechanical design, to the carrier element is preferably pressure-stable up to a pressure of more than 20 bar, preferably more than 80 bar.

Compounds which improve the electrical, thermal and / or magnetic conductivity of the bonding layer can be added to the metallic bonding layer. Alternatively or additionally, compounds which allow a better thermal expansion match between the materials of the carrier element and the sensor may also be added to the metal of the attachment layer.

A compound for improving the electrical conductivity are preferably solderable and at the same time conductive compounds, such as the compounds mentioned above,

Compounds which improve the thermal conductivity can be, for example, silicon carbide and / or aluminum nitride.

Compounds which allow a better thermal expansion adjustment may preferably be corundum and / or alumina.

Compounds which improve the magnetic conductivity can be, for example, magnetic iron or magnetizable metals or metal alloys.

The fluid channel 5 of the sensor 1 as well as the Fluidzuführkanal and -abführkanal 15 and 16 the carrier element 14 has a parylene coating 10 on. This is preferably distributed over the entire fluid-contacting region of the measuring arrangement. The coating is particularly preferably seamless.

However, in a less preferred embodiment, the parylene coating can only be in the bypass or in the second channel segment 18 the carrier element 14 and in the fluid channel 5 of the sensor 1 be arranged.

The order of parylene coating 10 can be done in the gas phase. In this case, para-xylene or a halogenated para-xylene is used as the starting material. About a per se known dimerization reaction and a subsequent decomposition reaction occurs in a high temperature zone to form a polymerizable species. This is reflected in the introduction into channel segments of the support element 14 and / or the fluid channel 5 of the sensor 1 on the local surface and forms a polymer layer, the parylene layer 10 , out.

The parylene layer can be formed in different layer thickness depending on the gas pressure and concentration of the starting material. This is preferably less than 5% of the nominal diameter of the inner diameter of the fluid channel, preferably less than 2% of the nominal diameter of the inner diameter of the fluid channel 5 of the sensor 1 , Typical layer thicknesses of the parylene layer 10 are for example 10 microns or less, preferably between 1 to 8 microns.

The parylene layer makes it possible to improve the chemical resistance in general and the corrosion resistance of the fluid channel in particular. Among other things, the corrosion resistance in the area of the fluid supply channel and the Fluidabführkanals 15 and 16 improved. The inner layer of Parylene is also diffusion-resistant.

The parylene coating may preferably consist of N, C, D, F and / or HT parylene. However, particular preference is given to HT-parylenes, ie the monofluorinated variant of the N-dimer of parylene.

The coating of the HT parylene withstands short-term temperature stresses of up to 450 ° C. Due to the high degree of splitting, HT-Parylene can also bond well to rougher surfaces. In addition, HT parylene has the lowest coefficient of friction compared to the other parylenes, thereby reducing the tendency of microparticle deposits.

The moisture permeability of the parylene coating is preferably less than 0.3 (g · mm) / (m ² · 24 h) relative at 37 ° C and 90% humidity, according to ASTM F1249 , according to the current version at the time of registration. Thus, the Parylenebeschichtung be referred to as diffusion-tight.

The tensile strength of the parylene coating is preferably more than 5000 psi, according to ASTM D882 , according to the current version at the time of registration. Due to this tensile strength of the continuous between the sensor and the support element layer is a dense Connection and an additional improved connection created in addition to the solder, adhesive and / or Halar bonding layer.

The Parylenebeschichtung is also preferably temperature resistant at media temperatures of more than 120 ° C. As a result, the coated measuring arrangement is suitable for a wide range of applications.

2 shows in a schematic way again the structure of the measuring arrangement with a micromechanical sensor and a carrier element 14 , One recognizes the micromechanical sensor, which both a first sensor body element 22 , which may consist of silicon, as well as a carrier element 14 directed layer 6 , which consists of borosilicate, for example. This layer 6 serves, inter alia, the better connection to the support element 14 and the thermal balance between the sensor body element 22 and the carrier element 14 , How therefore in 2 illustrated, the micromechanical sensor may be formed multi-layered.

The actual mechanical connection is made by the connection layer 39 eg by a gold / tin solder, a Halar compound and / or an adhesive. The carrier element 14 in turn is a metal body.

In 2 In addition, the fluid channel is shown, which is in the second cable segments 18 and one in the sensor body 2 arranged fluid channel 5 divided. In this fluid channel is the Parylenebeschichtung according to the aforementioned application method 10 applied.

Parylene is also FDA-certified and biocompatible. Therefore, the measuring arrangement can i.a. also be used in the medical sector and in the food sector.

In addition, the Parylenebeschichtung is preferably made transparent.

LIST OF REFERENCE NUMBERS

1

 sensor

2

 sensor body

3

 First connection opening

4

 Second connection opening

5

 fluid channel

6

 layer

10

 Parylene

14

 support element

15

 fluid supply

16

 Fluidabführkanal

17

 first channel segment

18

 second channel segment

20

 Channel link segment

21

 connecting element

22

 Sensor body element

38

 solder wires

39

 solder rings

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

• EP 2013/071617 [0002]
• DE 102013017317 A1 [0002]

Cited non-patent literature

• ASTM D882 [0010]
• ASTM F1249 [0011]
• ASTM F1249 [0082]
• ASTM D882 [0083]

Claims (9)

Measuring arrangement comprising a) a carrier element ( 14 ) with a longitudinal axis (A) on or on which a micromechanical sensor ( 1 ) is arranged for determining a process variable of a gaseous or liquid fluid, and b) the micromechanical sensor ( 1 ) for determining a process variable of a gaseous or liquid fluid with a sensor base body ( 2 ), which has a fluid channel ( 5 ) located inside the sensor ( 1 ) extends from a fluid inlet to a fluid outlet, and c) wherein the carrier element ( 14 ) a fluid supply channel ( 15 ) for supplying the fluid to the sensor ( 1 ) and a Fluidabführkanal ( 16 ) for removing the fluid from the sensor ( 1 ), characterized in that the fluid supply channel ( 15 ) of the carrier element ( 14 ) at least partially a parylene coating ( 10 ), which extend over the fluid channel ( 5 ) of the sensor ( 1 ) into the fluid discharge channel ( 16 ) of the carrier element ( 14 ). Measuring arrangement according to claim 1, characterized in that the parylene coating ( 10 ) has a layer thickness of less than 5% of the nominal diameter of the inner diameter of the fluid channel ( 5 ) of the sensor ( 1 ), preferably less than 2% of the nominal diameter of the inner diameter of the fluid channel ( 5 ). Measuring arrangement according to claim 1 or 2, characterized in that the parylene coating ( 10 ) has a tensile strength of 5000 psi, preferably greater than 7000 psi, according to ASTM D882. Measuring arrangement according to one of the preceding claims, characterized in that the moisture permeability of the parylene coating ( 10 ) Is less than 0.3 (g · mm) / (m ² · 24 h), preferably less than 0.25 (g · mm) / (m ² · 24 h), relative at 37 ° C and 90% humidity, according to ASTM F1249. Measuring arrangement according to one of the preceding claims, characterized in that the parylene coating ( 10 ) consists essentially of HT-parylene. Measuring arrangement according to one of the preceding claims, characterized in that the carrier element ( 14 ) for the mechanical connection of the Fluidzuführkanals ( 15 ) and / or the Fluidabführkanals ( 16 ) of the carrier element ( 14 ) with the fluid channel ( 5 ) of the sensor ( 1 ) a connection layer ( 30 ) which extends over a portion of a surface of the carrier element ( 14 ) and over a portion of a surface of the sensor ( 1 ). Measuring arrangement according to claim 7, characterized in that the connection layer ( 30 ) is a polyfluorinated plastic, in particular Halar, and / or a metal solder and / or an adhesive. Method for applying a polymer layer, in particular a parylene layer, in a measuring arrangement, in particular a measuring arrangement according to claim 1, characterized in that the polymer layer formation takes place by supplying a gaseous starting material to a surface, in particular a measuring medium-contacting surface, the measuring arrangement and wherein a polymer layer ( 10 ) is deposited by polymerization of the gaseous starting material on at least the surface of the measuring device. A method according to claim 8, characterized in that in the measuring arrangement existing fluid-conducting channel is used in the application of the polymer layer as a reaction chamber.

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