WO2010079206A1 - Accumulating moisture sensor - Google Patents

Abstract

The invention relates to a sensor device 1 for monitoring the state and corrosion in, for example, an aircraft, comprising a capacitor arrangement 20 and a moisture-binding layer 24. The capacitor arrangement 20 is designed to change the capacitance thereof as result of water absorption of the moisture-binding layer 24. The moisture-binding layer 24 can be arranged on the capacitor arrangement 20 in such a way that the water is absorbed irreversibly. In this way, an accumulating moisture sensor can be realized.

Description

 Accumulating humidity sensor

FIELD OF THE INVENTION

The invention relates to condition and corrosion monitoring for example for aircraft. In particular, the invention relates to a sensor device for an aircraft, in which an accumulated moisture as a measure of possible corrosion changes a capacitance of a capacitor arrangement and thus allows conclusions about a state of corrosion.

BACKGROUND OF THE INVENTION

In aviation, aircraft and in particular the surfaces of aircraft are subjected to high loads and must meet very high safety standards. Metal surfaces of these aircraft, which come into contact with moisture, can cause corrosion. Moisture is almost unavoidable, especially through use in different climatic conditions, as well as changing

Warm-up and cool-down phases that may cause condensation of humidity.

The condition of the aircraft, in particular the extent of corrosion, must be monitored to ensure the safety of the aircraft. This can be done with the help of a so-called corrosion monitoring. In this case, mechanical, electrical or electrochemical probes or sensors are exposed to the same conditions as the aircraft itself. Due to climatic and environmental influences, changes in measured variables of the probes or sensors can be caused. These changes can be detected and read out. Accordingly, it can be concluded from the changes in the measured quantities on the extent of corrosion.

In the case of the conventionally used electrical or electrochemical probes or sensors, it is possible to detect a momentary change in the measured variables of the probes or sensors and thus to determine or calculate the instantaneous corrosion load / u. However, these probes or sensors can also have reversible effects that can cancel a change in the measured variable once caused, for example, by evaporation of a moisture once absorbed. Probes or sensors of this type must be read out continuously in order to determine the corrosion load over the service life and possibly the entire service life of the aircraft via the permanent change of the measured variables.

Especially in aircraft, continuous readout can lead to high overhead in the form of long maintenance times and associated increased costs. Furthermore, in the case of conventional probes or sensors, in the event that the change in the probe or sensor characteristics can not be continuously read out, the safety of the aircraft may be impaired. no longer guaranteed, in particular, when reversible effects occur, although the sensor or the sensor return to a previous measurement state, but not the corrosion state of the component to be monitored.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved sensor device for condition and corrosion monitoring in, for example, aircraft, which In particular, cumulatively, ie over a longer period of time, it is possible to record and retain properties.

The object of the present invention is achieved by the subject matter of the independent claims, preferred or advantageous developments are represented by the dependent claims.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the sensor device comprises: a capacitor arrangement having a first electrode, a second electrode, a moisture-absorbing layer, which is arranged with respect to the first electrode and the second electrode such that the capacitor arrangement changes its capacity when the moisture-absorbing layer absorbs moisture, and a moisture diffusion diffusion-reducing barrier which covers the moisture-absorbing layer.

By means of a capacitor arrangement structured in this way, the capacitance of the capacitor arrangement can be changed by means of a liquid storage in a moisture-absorbing layer. The moisture present on the sensor device over a certain period of time accumulates in the moisture-absorbing layer and in this way changes its relative permittivity. Since water has a relative dielectric constant of about 81, even a slight absorption of water leads to a change in the measured value of the capacitance value, provided that the wasscraufnehmende part is in a position close to the capacitor array. The moisture-absorbing layer can be arranged both between the first and the second electrode, as well as in its vicinity, in which case the inhomogeneous region of the capacitor arrangement contributes to the capacitance change. A cover of the moisture-absorbing Layer through a moisture diffusion-inhibiting barrier can on the one hand prevent over-rapid saturation of the moisture-absorbing layer and thus allow an extension of the period of use; however, such a barrier may also prevent or at least slow down the delivery of moisture once absorbed. A sensor device described above thus allows an integral statement about the moisture that is exposed to this sensor device and thus also an analogously arranged component over at least one service interval or over the entire life of the aircraft. The data used to determine the load or corrosion can be read in each case during the execution of the usual service and maintenance. As a result, costs for additional wiring and stationary readout devices can be avoided. In addition, valuable space in the aircraft, which would be necessary for the devices and cables, can be saved. Furthermore, maintenance of additional equipment and cables is not necessary.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the capacitor arrangement is formed as an interdigital capacitor and the first electrode and the second electrode are formed in a surface, wherein the moisture-absorbing layer areally and electrically isolated to the first electrode and the second electrode is disposed on the surface.

In the case of a secondary digital capacitor, the electrodes engage in one another in a comb-like or meandering manner. These branches or turns of the individual electrodes can, for example, be in the range of a few micrometers. Due to the strong inhomogeneity, the sensitivity of the capacitor can be increased even for minor changes from the outside. Through the use of interdigital capacitors in corrosion monitoring in aircraft can a better measurement accuracy can be achieved. An interdigital capacitor can be arranged flat on a surface or Obei surface. This surface can be flat or curved. In particular, the dnterdigitalkondensatoranordnung can muster by simple Fertigungsprozessc. This can be done either on a substrate, but also on the component itself. Insofar as a curved surface is possible for such embodiments, so that the component not the capacitor form, but the capacitor assembly can be adapted to the component. It is understood that certain isolation conditions must be met to ensure the function of the capacitor. The moisture-absorbing layer is flat on the surface

Elekrodenanordnung attached. Due to the proximity of the moisture-absorbing layer to the dielectric-relevant part of the capacitor, the capacitance value of the capacitor is measurably changed upon moisture absorption. The distances can be in the range of a few micrometers, for example between 10 μm and 50 μm. Due to the surface coverage of the moisture-absorbing layer, a sufficient measurability and measurement accuracy is possible.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein between the first electrode and the second electrode on the one hand and the moisture-absorbing layer on the other hand, a moisture-impermeable layer is provided.

For example, the moisture-absorbing layer may be arranged such that the moisture from both surface sides of the moisture-absorbing layer has access to the moisture-absorbing layer. However, a sensor device with a much smaller height is possible if the moisture-absorbing layer rests directly on the electrodes, only by a moisture-impermeable layer separated. The moisture-diffusion-barrier is then provided only on the side facing away from the moisture-impermeable layer side of the moisture-absorbing layer. If the planar electrode assembly is accessible from both sides for moisture, either on both sides of a moisture-absorbing layer may be provided which is each isolated to the electrode assembly by a moisture-impermeable layer, or the moisture-absorbing layer only electrically isolated to the electrode assembly, but of be accessible to both sides of the ambient humidity. In the latter case, the barrier is covered from both sides of the moisture-absorbing layer. The moisture absorption then takes place from one side through the electrode arrangement.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture-absorbing layer has a high moisture-absorbing material.

By a highly moisture-absorbing material is usually provided a material that has a high affinity for water and the once absorbed water does not give off easily. Such a material absorbs the water, for example, absorbing. A limitation of the water absorption can then take place through the barrier, which limits the access of moisture. Once passed through the barrier, the highly moisture-absorbing layer then absorbs the water sometimes completely, as far as its moisture absorption capacity allows. According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture-absorbing layer comprises a polymer with incorporated particles of a highly moisture-absorbing material.

The polymer can serve as a kind of carrier material for the moisture-absorbing material. This is particularly useful in cases where the moisture-absorbing material itself is not easy to process or apply, such as when it is in crystalline form. The polymer can also cause some attenuation of the upcoming liquid. Further, the polymer may perform a liquid transport function that effects transport of the liquid to the moisture-absorbent material.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture-absorbing layer is designed to absorb moisture irreversibly.

In addition to the moisture-diffusion-inhibiting barrier, the moisture-absorbing material or, more generally, the moisture-absorbent material may also be used

Layer even prevent the release of a once absorbed moisture.

On the one hand, this can be achieved through an appropriate choice of the moisture-absorbent

Materials are made, but also on the choice of a corresponding polymer or a further barrier effect in the layer interior.

According to one embodiment of the invention, a sensor device for

Condition and corrosion monitoring provided, whereby the moisture Aufnehraendc layer as a moisturizing material has a nanoscale adsorbent.

Nanoscale here means that the materials are present as a multiplicity of particles or molecules. The size of the particles is in the range of a few nanometers (nm). Adsorbents in the context of the invention are solid substances which are able to selectively enrich certain substances (such as water) from an adjacent gaseous or liquid phase at their interface. The hygroscopic materials used for the coating may be hydrophilic or polar adsorbents.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture-absorbing layer as the moisture-absorbing material comprises a material consisting of a group consisting of zeolite, silica gel, calcium chloride, alkali metal hydroxide (eg sodium hydroxide, potassium hydroxide) and alkaline earth oxides (eg magnesium oxide, calcium oxide ).

Moisture-absorbent materials include, for example, hydrophilic materials such as zeolites, silica gels, calcium chloride (CaCl ₂ ), and alkali hydroxides. These materials may have the property of absorbing water molecules from the environment by absorption or adsorption. For example, moisture from the environment, in particular in the form of water vapor from the air, can be bound by hygroscopic materials. The hygroscopic materials may be contained or embedded as particles in another material of the layer. The hygroscopic materials can be arranged in the immediate vicinity of the electrode geometry. The layer thickness in which the hygroscopic materials are contained can be found in the Be range of a few microns, for example, about 10 to 50 microns.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein a moisture-transporting layer is provided between the moisture diffusion-reducing barrier and the moisture-absorbing layer.

The moisture transporting layer can provide some dampening of moisture wicking and also result in even distribution of moisture to the moisture absorbent material. Furthermore, the transport layer can serve as a carrier for the diffusion-reducing barrier.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture-transporting layer comprises a polymer.

In this case, the transport layer and the moisture-absorbing layer can be represented only by a partial accumulation of moisture-absorbent material in an otherwise homogeneous polymer matrix. The production costs for the stratification can be reduced by using only the polymer as starting material and subsequently changing the different ranges in their properties by further steps.

According to one embodiment of the invention, there is provided a sensor device for condition and corrosion monitoring wherein the polymer comprises a material selected from the group consisting of polysulfone and phthalocyanine. The polymer layer may have, for example, polysulfones and / or phthalocyanines in its water-absorbing region. The highly hygroscopic particles can be embedded or arranged in the water-absorbing region of the polymer layer. This may be followed by another water-absorbing region of the polymer layer, which has no hygroscopic particles. It may be advantageous that the water-casconcorbent area without the hygroscopic particles is arranged closer to the air and thus to the air humidity than the area with the hygroscopic particles, since in this way a diffusion of water through the well-water-conducting or -absorbing area the polymer layer is made possible. Thus, the water can be transported through the water-absorbing area to the area with the water-attracting particles, where it can be irreversibly absorbed.

According to an embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture diffusion barrier diffusion barrier is formed as a separate layer.

Such a separate barrier layer can be subjected to a separate production process and then applied to a carrier material. This allows to adapt the barrier material according to the requirements of a barrier.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture diffusion barrier comprises a material from a group consisting of polytetrafluoroethylene, modified polytetrafluorethylene, polyethylene and polypropylene.

Such materials, with a corresponding design, have limited moisture permeability. In particular, polyletrafluoroethylene, when designed as a micromembrane, has an impermeability to the liquid state of matter of water, but permeability to the gaseous state. In this way, for example, an effective protection against upcoming liquids can be achieved, in particular if the sensor device is exposed to direct weather influences such as rain.

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the moisture diffusion-reducing barrier is formed by a modified surface of a moisture diffusion-reducing barrier-bearing layer.

By a surface treatment, a direct modification of the Tiägermatcrials be made without a subsequent application of the Barricrematerials would be necessary. In particular, in the case of a polymer matrix which has a moisture-absorbing material in certain layers in order to form both the transport layer and the moisture-absorbing layer, the subsequent surface treatment is simple and integral in terms of production, so that, for example, detachment of the layers can also be avoided. According to one embodiment of the invention, there is provided a sensor device for condition and corrosion monitoring, wherein the modified surface is a plasma treated surface.

The plasma treatment allows the surfaces to be modified evenly and effectively, it can be done with relatively simple

Plasma generating devices, such as Elektrodenanordnungcn made. The layer thickness is low, so that the overall height can also be kept low,

According to one embodiment of the invention, a sensor device for state and corrosion monitoring is provided, wherein the Scnsorvoπϊchtung invention further comprises an inductance, wherein the capacitor arrangement and the inductance are formed as parts of a resonant circuit.

The resonant circuit can be excited to vibrate from the outside. Assuming constancy of the inductance, the resonant frequency of the resonant circuit provides information about the capacitance value of the capacitor arrangement. The capacitance value in turn gives, with known geometry of the capacitor arrangement, information about the effective relative dielectric constant of the capacitor and thus about the degree of the stored moisture. Thus, the resonance frequency is directly linked to the amount of stored moisture. Furthermore, the resonant circuit may include an identification integrated circuit (IDIC). The individual components of the resonant circuit can be connected in series or in parallel.

According to one embodiment of the invention, an RFID is provided with a resonant circuit with a sensor device according to the invention. The Radio Frequency Identifier RFID enables identification of objects equipped with RFID components. An RFID component odci RFID tag with a resonant circuit may be incorporated in a structure to be monitored or attached to it. For example, an RFID tag with a sensor device according to the invention can be arranged on a metallic outer surface of an aircraft. For example, a passive RFID tag may be excited to vibrate and then itself emit energy corresponding to a particular frequency, the resonant frequency. The radiated sequence can be detected. Subsequently, certain changes, such as a change in the capacitance of the capacitor arrangement, can be derived therefrom. The configuration of the sensor device as an RFID resonant circuit may be advantageous, since in this way the information about the extent of the corrosion that has been integrated or irreversibly recorded in the moisture-wetting layer of the capacitor arrangement can be wirelessly interrogated and transmitted. Thus, for example, the capacity change data can be retrieved when needed, for example, during a service operation.

The sensor device according to the invention may be arranged, for example, at one or more points of the aircraft, which come into contact with the outside air and thus with the humidity. For example, the sensor device can be arranged on an aircraft skin of the wings or the fuselage of an aircraft. Furthermore, the sensor device can be arranged on devices and devices, such as antennas, which are located on the outside

Aircraft are attached. Aircraft may, for example, be airplanes and helicopters. However, the sensor device can also be designed for other liquids in order to detect aggressive solvents, for example. The moisture-absorbing layer and moisture diffusion-inhibiting layer can then be adapted accordingly.

Of course, the individual features can also be combined with each other, which can also be partially beneficial effects that go beyond the sum of the individual effects.

These and other aspects of the present invention are achieved by the

Reference will be made and illustrated with reference to the exemplary embodiments described hereinafter.

DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described below with reference to the following figures.

Fig. 1 shows an exemplary embodiment of a sensor device with

Interdigital capacitor according to an exemplary embodiment of the invention.

FIG. 2 shows a further exemplary embodiment of the invention having an interdigital capacitor with a transport layer. Fig. 3 shows a further exemplary embodiment of the invention with

Interdigital capacitor with a stored moisture-absorbing material.

4 shows a sectional view of an exemplary embodiment of a sensor device with an interdigital capacitor with bilateral moisture-removing layers.

Fig. 5 shows an exemplary embodiment of the invention with interdigital capacitor with a one-sided moisture-absorbing

Layer.

6 shows a schematic view of an RFID with a resonant circuit.

FIGS. 7 and 8 show an exemplary embodiment of an RFID with a sensor device according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION EXAMPLE

EMBODIMENTS

FIG. 1 shows an exemplary embodiment of a sensor device in a sectional view. On a support surface 7, which may be for example a board or a component, for example, an aircraft, is a

Capacitor arrangement arranged with a first electrode 21 and a second electrode 22. The plurality of electrodes shown here may each be connected to each other, so that they result in a Elektrodcnanordnung, for example incinerate and thereby form a capacitor arrangement, such as an interdigital capacitor. The capacitor assembly 20 further includes a moisture-absorbing layer 24 disposed with respect to the first electrode and the second electrode such that the capacitor changes its capacitance upon moisture absorption of the moisture-absorbing layer 24. When a moisture absorption of the moisture-absorbing layer 24 water is stored in the moisture-absorbing layer. The water has a relatively high dielectric constant of about 81. Compared to a layered material that has not yet absorbed moisture, the effective relative dielectric constant in the water absorbed state is much higher. In this way, the capacitance value of the capacitor arrangement with the electrodes 21, 22 is changed. The capacitance value of the electrodes 21, 22 is determined not only by the homogeneous region lying between the electrodes, but also by the inhomogeneous region, which is located above the electrodes in the view shown in FIG. Within this inhomogeneous region, the moisture-absorbing layer 24 is arranged in the embodiment shown in FIG. If the sensor device 10 shown in FIG. 1 now absorbs moisture in its moisture-absorbing layer 24, the capacitance value of the capacitor arrangement 20 changes, which in turn can be used as a measure of moisture absorption in a moisture-absorbing layer 24. The moisture-absorbing layer 24 is covered with a moisture diffusion-reducing barrier 26. In this way, the moisture absorption of the moisture-absorbing layer 24 is limited in terms of quantity over a certain period of time, so that saturation of the moisture-absorbing layer 24 does not occur in good time. In this way, an increasing moisture content over a long period of time can be ensured, so that the sensor device 10 over a relatively long period can continuously absorb moisture in the moisture-absorbing layer 24. The moisture absorption in the moisture-absorbing layer 24 can be irreversible, so that a reversing effect of a moisture release can be substantially prevented. In this way, the sensor device 10 can provide information about which integral moisture load the sensor device and thus also an analogously arranged, subjected to a moisture load component is exposed in order to obtain a conclusion on aging or corrosion.

Although the electrodes 21, 22 are arranged in one plane in FIG. 1, the electrodes 21, 22 may also be arranged in a curved surface which follows, for example, the curvature or the external shape of a component. In this way, the sensor device can be adapted to a component whose corrosion behavior is to be monitored. In the arrangement shown in FIG. 1, a moisture-impermeable layer 23 is provided between the moisture-absorbing layer 24 and the electrodes 21, 22, which prevents an uncontrolled absorption of moisture by the moisture-absorbing layer 24. In addition, in the embodiment shown in FIG. 1, the layer 23 is also electrically insulating, so that the electrodes 21, 22 are not short-circuited by the moisture-absorbing layer 24, in particular if the moisture-absorbing layer 24 becomes conductive due to the absorption of moisture.

FIG. 2 shows a further exemplary embodiment of a sensor device. As in FIG. 1, the electrodes 21, 22 are formed on a surface 7 which, in the embodiment shown here, can be both planar and curved. Above the moisture-absorbing layer already described is a Moisture transporting layer 25 is provided, which allows a moisture transport to the moisture-absorbing layer 24. In the embodiment shown in FIG. 2, both layers are covered by a diffusion-reducing barrier 26. The moisture diffusion-reducing barrier 26 can be used regardless of

Presence of the transport layer 25 may both be a separately formed layer, as well as in a modified surface of a carrier layer. In the latter case, the moisture diffusion-reducing barrier is made substantially thinner. As the carrier layer for the diffusion-reducing barrier 26, both the transport layer 25 and the moisture-absorbing layer 24 can serve. A surface modification can be done for example by a plasma treatment. The layers shown in the figures need not necessarily have a uniform thickness, but may also have different thicknesses. Furthermore, the thickness can also be configured over the surface area.

FIG. 3 shows a further exemplary embodiment of the invention. In the embodiment shown in FIG. 3, the electrodes 21, 22 are again arranged on a surface 7. Moisture-absorbing materials are embedded in the moisture-absorbing layer 24 in the form shown in FIG. 3, for example in the form of particles 27. The moisture-absorbing layer 24 and the transport layer 25 can be configured in a common polymer matrix, wherein only in the moisture-absorbent layer 24, the moisture-absorbing particles 27 are provided. Of course, the layers 24 and 25 may be configured separately even when providing moisture-absorbing material or particles 27, as it is written in Figures 1 and 2. Furthermore, a moisture diffusion-reducing barrier 26 is again provided which In this embodiment, it may be configured both as a separate layer and as a surface-modified layer. It should be noted that, in particular in the embodiment shown in FIG. 3, a polymer matrix may be provided in which a moisture-absorbing material 27 is provided in a specific layer, in an overlying layer only the polymer matrix without an interposed moisture-absorbing material as transport layer 25 is provided , and the polymer matrix is surface-modified on its surface such that the surface-modified surface is a moisture diffusion-reducing barrier 26. Such an arrangement is shown in FIG. Insofar as the polymer matrix and the moisture-absorbing material embedded therein does not short-circuit the electrodes 21, 22, the polymer matrix can also be applied directly to the electrode 21, 22. In this way, a uniform polymer matrix can be formed in which a moisture-absorbing material, for example in the form of embedded particles 27 can be provided near the electrodes, an overlying transport layer can be realized, and a moisture diffusion-reducing barrier on the surface of the polymer matrix facing away from the electrodes 26 can be realized. In this way, a sensor device according to the present invention can be produced relatively efficiently and simply.

FIG. 5 shows a further exemplary embodiment of a sensor device 10. While the sensor device according to FIGS. 1 to 4 was designed essentially for a moisture absorption from one side, the embodiment shown in FIG. 5 is provided for a moisture absorption from two sides. The electrodes 21, 22 of a capacitor are embedded here in a layer 23 which is moisture impermeable. If necessary, this layer 23 can also be made electrically insulating. In close proximity to the electrodes 21, 22 is a moisture-absorbing layer 24 is provided on both sides, which is sealed against moisture by the moisture-impermeable layer 23 in each case toward the side facing the electrodes. The side of the moisture-absorbing layer 24 facing away from the electrodes 21, 22, on the other hand, is designed with a barrier 26 which reduces moisture diffusion. This barrier may, for example, constitute a separate layer but also a modified surface of a carrier material. The embodiment shown in FIG. 5 is suitable, for example, for an upright mounting which allows a moisture absorption from both sides of the capacitor arrangement. In this way, the sensitivity of the capacitor arrangement is increased. It should be understood that the embodiment shown in FIG. 5 essentially represents a duplication of the sensor devices shown in FIGS. 1 to 4, which is designed to be mirrored doubled with respect to the plane 7. In this case, the concrete embodiment shown in FIG. 5 corresponds to the doubled arrangement according to FIG. 1. However, it should be understood that the arrangements shown in FIGS. 2, 3 and 4 can likewise be designed to be doubled in an analogous manner.

FIG. 6 shows a further exemplary embodiment of the invention, in which the moisture-absorbing layer 24 is provided in the immediate vicinity of the electrodes 21, 22. In contrast to the embodiments described above, the embodiment shown in FIG. 6 does not have a moisture-impermeable layer 23. Rather, the moisture-diffusion-reducing barrier 26 covers the moisture-receiving layer on both sides. In this way, a moisture absorption is possible not only from the side facing away from the electrodes 21, 22 side of the moisture-absorbing layer 24, but also on the electrodes 21, 22 side facing, quasi through the electrode assembly. Likewise, it should be understood that the electrodes 21, 22 can directly adjoin the moisture diffusion-reducing barrier 26, thus the Arrangement of the moisture absorption layer 24 and the moisture diffusion-reducing barrier 26 can serve as a support for the electrode arrangement 21, 22. Although not explicitly shown in FIG. 6, a moisture transport layer 25 can also be provided in an analogous manner, which can be provided on the moisture-absorbing layer 24 both on one side and on both sides. Likewise, in turn, a polymer matrix may be provided in which a moisture-absorbing material, for example in the form of particles 27, is embedded in a specific layer 24. Furthermore, a moisture transporting layer 25 may be provided in the polymer matrix. By modifying the surface, the polymer matrix may also form the moisture diffusion-reducing barrier, which barrier may be provided both directly on the moisture-receiving layer and on the moisture-transporting layer 25.

It should be noted that the embodiments shown in FIGS. 1 to 6 may all represent capacitor arrangements of an interdigital capacitor, in which the corresponding electrodes mesh in the form of elongated electrodes in a comb or meander shape, in order to represent a capacitor-carrying capacitor arrangement. As can be seen from FIGS. 1 to 6, such a capacitor arrangement can be formed, in particular, on a surface 7, so that the layered electrode arrangement otherwise customary for plate capacitors can be dispensed with. Rather, such an interdigital condenser has a relatively small or no homogeneous region, but essentially only inhomogeneous regions. However, this makes the Interdigitalkondcnsator sensitive to external influences, so that it is particularly suitable for sensor or detector arrangements. FIG. 7 shows an arrangement of a sensor device with a capacitor arrangement 20 and an inductance arrangement 30. Both the inductance arrangement 30 and the capacitor arrangement 20 are designed such that they can be formed on a surface or a plane. This makes such an arrangement suitable for attaching these, for example, to circuit boards having a relatively low height. Such an interconnection of inductance and capacitor represents a resonant circuit, which forms a characteristic resonant circuit frequency with an unchanged geometry. This resonant circuit frequency is essentially dependent on the inductance and the capacitance. Will now the

Capacitor assembly 20 according to the embodiments described above, provided with a moisture-absorbing layer 24, the resonant circuit frequency can be changed by changing the capacitance of the capacitor assembly 20. Such an arrangement is shown in FIG. Essentially, the geometry of both the

Inductance 30 and the capacitor assembly 20 unchanged. The substantially only change in the capacitance of the capacitor assembly 20 is due to the moisture in the moisture-absorbing layer 24, through which the capacitance of the capacitor assembly 20 changes. In this way, at the same time the resonant circuit frequency changes, so that the resonant frequency of the resonant circuit or a shift of the resonant frequency can be used as a measure to ultimately determine the moisture absorption in the moisture-absorbing layer 24.

The arrangements shown in FIGS. 7 and 8 can be designed, for example, in a very flat design. Furthermore, the arrangements shown in Figures 7 and 8 as so-called Radio Frequency Identifier RFID components be configured, which can be excited by means of an external magnetic alternating field to a vibration, so that these RFID give due to the then adjusting the resonant frequency of the resonant circuit information about what moisture storage level has reached the moisture-absorbing layer 24. In this way, the sensor device 10 can be read without an electrical contact. In particular, the integrity of the capacitor arrangement can be maintained, so that no external electrical access is necessary.

It should be noted that the present invention besides the

Areas of application of aviation can also be used in other areas, where it is about the monitoring of moisture conditions or corrosion hazards. In particular, such devices can be used when it comes to the monitoring of permitted humidity values, for example, to be able to monitor compliance of consumer products, for example, warranty conditions.

It should be noted that the term "comprising" does not exclude other elements or method steps, just as the term "a" and "an" does not exclude multiple elements and steps.

The reference numerals used are for convenience of reference only and are not to be considered as limiting, the scope of the invention being indicated by the claims. BEZUGSZEICHENUSTE

10 sensor device

7 area in which the Kondensatoreleklroden are arranged

20 capacitor arrangement

21 first electrode

22 second electrode 23 moisture-impermeable layer

24 moisture-absorbing layer

25 transpoil layer

26 moisture diffusion-reducing barrier

27 moisture absorption s material 30 inductance

Claims

claims A sensor device (10) for condition and corrosion monitoring, the sensor device comprising: a capacitor assembly (20) having a first electrode (21), a second electrode (22), a moisture-receiving layer (24) relative to the first electrode (21) and the second electrode (22) are arranged such that the capacitor assembly (20) changes its capacitance upon moisture absorption of the moisture-absorbing layer (24) and a moisture diffusion-reducing barrier (26) covering the moisture-absorbing layer (24). 2. Sensor device according to claim 1, wherein the capacitor arrangement (20) is formed as an interdigital capacitor and the first electrode (21) and the second electrode (22) in a surface (7) are formed, wherein the moisture-absorbing layer (24) and surface electrically isolated from the first electrode (21) and the second electrode (22) on the surface (7) is arranged. 3. Sensor device according to claim 2, wherein between the first electrode (21) and the second electrode (22) on the one hand and the moisture-absorbing layer (24) on the other hand, a moisture-impermeable layer (23) is provided. 4. Sensor device according to one of claims 1 to 3, wherein the moisture-absorbing layer (24) has a strong moisture-absorbing material. 5. Sensor device according to one of claims 1 to 4, wherein the moisture-absorbing layer (24) comprises a polymer with incorporated particles of a strong moisture wedge-receiving material. 6. Sensor device according to one of claims 1 to 5, wherein the moisture-absorbing layer (24) is adapted to absorb moisture irreversibly. 7. Sensor device according to one of claims 1 to 6, wherein the moisture-absorbing layer (24) has a nanoscale adsorbent as Feuchligkeitsaufnehmendes material. 8. A sensor device according to any one of claims 1 to 7, wherein the moisture-absorbing layer (24) as the moisture-absorbing material comprises a material selected from a group consisting of zeolite, silica gel, calcium chloride, alkali hydroxide, calcium oxide and magnesium oxide. 9. A sensor device according to any one of claims 1 to 8, wherein between the moisture diffusion-reducing barrier (26) and the moisture-absorbing layer (24) a moisture-transporting layer (25) is provided. 10. Sensor device according to claim 9, wherein the moisture-transporting layer (25) comprises a polymer. 1 1. A sensor device according to any one of claims 4 to 10, wherein the polymer comprises a material selected from a group consisting of polysulfone and phthalocyanine, 12. Sensor device according to one of claims 1 to 11, wherein the moisture diffusion-reducing barrier (26) is formed as a separate layer, The sensor device of claim 12, wherein the moisture diffusion-reducing barrier (26) comprises a material selected from the group consisting of polytetrafluoroethylene, modified polytetrafluoroethylene, polyethylene and polypropylene. 14. A sensor device according to any one of claims 1 to 11, wherein the moisture dissociation diffusion-reducing barrier (26) is formed by a modified surface of a moisture diffusion-reducing barrier (26) bearing layer (24, 25). The sensor device of claim 14, wherein the modified surface is a plasma treated surface. 16. Sensor device according to one of claims 1 to 15, further comprising an inductor (30), wherein the capacitor arrangement (20) and the inductance (30) are formed as parts of a resonant circuit. 17. RFID with a resonant circuit with a sensor device according to claim 16.