WO2012126960A1

WO2012126960A1 - Sensor fiber and sensor fiber arrangement

Info

Publication number: WO2012126960A1
Application number: PCT/EP2012/055033
Authority: WO
Inventors: Günter SCHULTES; Jochen BOCK; Dirk GÖTTEL
Original assignee: Hochschule für Technik und Wirtschaft; ZeMA gGmbH
Priority date: 2011-03-24
Filing date: 2012-03-21
Publication date: 2012-09-27
Also published as: DE102011015081A1; DE102011015081B4

Abstract

The invention relates to a sensor fiber for measuring a deformation, comprising: a fiber core (2) that is not conductive at least on the fiber core lateral face; and a sensor layer (3) that surrounds the fiber core; wherein the sensor layer (3) contains a material which contains carbon and in which clusters (4) made of a conductive cluster material are embedded, said clusters (4) being separated from each other by the material which contains carbon.

Description

DESCRIPTION Sensor fiber and sensor fiber arrangement

Technical area

The present invention relates to a sensor fiber, in particular a sensor fiber, which represents a change in length due to tension or pressure in the form of a change in electrical resistance.

PRIOR ART Sensor fibers for measuring forces and pressures are known from the prior art

Technique known. For example, document DE 10 2008 058 882 A1 shows a fiber-reinforced plastic structure which comprises reinforcing fibers embedded in plastic and sensor fibers contained therein. The sensor fibers have an electrical conductivity, which at one by the action of a force

caused change in length of the sensor fibers changes. This makes it possible to easily determine stresses due to compressive or tensile forces in fiber-reinforced plastic structures.

Known sensor fibers for detecting a tensile force are usually made of metallic material. However, this material has the disadvantage that it has only a low k-factor of about 2. The k-factor indicates the ratio of a resistance change to a change in length of the sensor fiber. The k-factor provides a direct measure of the sensitivity of one with such

Sensor fiber constructed sensor.

For many applications, however, the sensitivity of such sensor fibers is not sufficient, so that other sensor materials can be avoided. Other sensor materials, such. For example, those made of ceramics or semiconductors, However, they have the disadvantage that they have a relatively low conductivity, so that their usability is limited, since a change in resistance at high resistances due to the resulting low currents is difficult to detect. In addition, such materials are often brittle, so that their reversibility of a change in length after application of a tensile force remains well behind that of metallic materials. Such sensor materials can therefore only be used in applications in which the expected

Length change of the sensor material remains within a predetermined range.

Particularly promising sensor materials are carbonaceous ones

Layers with Clusters of Conductive Cluster Material e.g. B. from the publication WO 2009/129 930 known. The clusters preferably include a metal and are embedded in the carbonaceous material so that the clusters are separated from each other by the carbonaceous material. Such carbonaceous materials have a high k-factor with relatively little electrical resistance, so that layers of this material are particularly suitable for use as a force or pressure sensor. The disadvantage is that such

Carbonaceous layers are brittle and therefore not for the formation of

Sensor fibers are suitable. Furthermore, such carbonaceous

Layers with embedded clusters only by a deposition process, e.g. a sputtering process, wherein the layer structure is relatively slow. A construction of a sensor fiber of significant thickness is therefore very expensive.

It is therefore an object of the present invention to produce a sensor fiber with a high sensitivity, which also has a high robustness. It is another object of the present invention to provide a sensor element with a

Sensor fiber and a manufacturing method for a sensor fiber to provide.

Disclosure of the invention This object is achieved by the sensor fiber according to claim 1 and by the sensor element with a sensor fiber and the method for producing a sensor fiber according to the independent claims. Further advantageous embodiments of the present invention are specified in the dependent claims.

According to a first aspect, a sensor fiber for measuring deformation is provided. The sensor fiber includes:

- A non-conductive at least on its lateral surface fiber core; and

a sensor layer surrounding the fiber core;

wherein the sensor layer comprises a carbonaceous material in which clusters of conductive cluster material are embedded, the clusters passing through the cluster

carbonaceous material are separated from each other.

One idea of the above sensor fiber is to use as sensor material for the

Sensor fiber to use a carbonaceous material, are introduced into the cluster of conductive material. The carbonaceous sensor material has the advantage of good temperature resistance and high sensitivity to tensile and compressive forces, i. H. a high k-factor. To one

To prevent tearing of the inherently brittle sensor material under a tensile load, it is provided to provide the sensor fiber with a completely non-conductive or at least on its outer surface non-conductive fiber core, which is capable of high tensile forces (tensile forces higher than the material of Sensor layer), and to surround the fiber core with the sensor material. The

Elongation of the sensor fiber due to an applied force is then largely determined by the elasticity of the sensor fiber. Such a sensor fiber can combine the advantages of high tensile strength with the advantage of high sensitivity.

The sensor material has an electrical conductivity that results from both the stretching or compression of the sensor fiber and from a pressure of a medium surrounding the sensor fiber, which in the radial direction of the sensor fiber works, depends. Thus, the sensor fiber can be flexibly employed in sensor assemblies for both tensile and compressive forces as well as pressures. It can be provided that the fiber core is completely formed from an electrically non-conductive material or comprises an insulated on its lateral surface electrical conductor. In particular, by the second-mentioned variant, it is possible to use the fiber core as an electrical conductor to

Signal transmission, energy transmission or as a measuring element e.g. for one

Temperature measurement can be used.

Furthermore, it can be provided that the sensor fiber comprises a non-conductive layer surrounding the sensor layer, which serves as an insulation layer and / or protective layer.

According to one embodiment, the sensor fiber may comprise an electrically conductive shield surrounding the sensor layer.

The sensor fiber may comprise a plurality of sensor sections, which are defined by at least one conductor layer, which is applied directly to the sensor layer in a region of the sensor fiber.

According to a further aspect, a sensor element is provided. The sensor element comprises:

a carrier material;

- At least one of the above sensor fibers, which is applied to the carrier material or introduced into the carrier material.

In this way, a sensor element is provided which is easy to manufacture and which can determine the integral deformation of a component over a larger range of distances. It can be provided that contact surfaces are provided for contacting the sensor fiber. In particular, the carrier material may be provided with a plurality of sensor fibers arranged in parallel, wherein the contact surfaces for the

Contacting the individual sensor fibers are arranged on a contact strip at one end of the carrier material. Between each two of the sensor fibers at different positions along the extension of the sensor fibers in the

Carrier material are arranged electrically conductive connections.

According to a further aspect, a textile fabric is provided with one or more of the above sensor fibers.

According to a further aspect, there is provided a method of manufacturing a sensor fiber, wherein a reactive PVD process comprising a sputtering material from a target onto a fiber core under a reactive atmosphere of a

carbonaceous gas containing in particular ethane, ethene or ethyne, is carried out so that the carbonaceous gas dissociates and a

carbonaceous layer is deposited on a surface of the fiber core, are embedded in the clusters of sputtering material, wherein the fiber core is passed through a tubular target while it is coated.

In another aspect, a method of manufacturing the above is

Sensor fiber provided, with a PVD process of a target with

carbonaceous material and metal-containing material is carried out on a fiber core under a non-reactive atmosphere of an inert gas, so that a carbonaceous layer of the carbonaceous material is deposited on a surface of the fiber core are embedded in the clusters of the metal-containing material, wherein the fiber core a tubular target is guided while being coated. Furthermore, the target of each other, in particular alternately, patch rings of the carbonaceous material and from the

be formed metal-containing material. Furthermore, the fiber core during the PVD process to a temperature below 600 ° C, in particular to a temperature between 150 ° C and 300 ° C, heated. It can be provided that the PVD process is carried out in a coating chamber, wherein the sensor fiber is connected at or behind the outlet of the coating chamber to a negative bias voltage, so that the located inside the coating chamber portion of the

Sensor fiber is electrically biased to perform a bias sputtering.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

Figure 1 is a perspective view of a sensor fiber according to a

embodiment;

Figure 2 cross-sectional view through the sensor fiber of Figure 1;

Figure 3 is another perspective view of another

Embodiment of a sensor fiber;

Figure 4 is an illustration of the use and contacting of

Sensor fiber for measuring forces acting mechanically on the sensor fiber;

Figure 5 shows a way to use the sensor fiber for a

Measuring a pressure of a medium in a pressure vessel;

Figure 6 is a cross-sectional view of the structure of a sensor fiber with multiple sensor sections; a plan view of an embodiment of a sensor element with a sensor fiber in the form of a strain gauge; a plan view of a further embodiment of a

Sensor element with a sensor fiber in the form of a

Strain gauge; a further embodiment of a sensor element with a plurality of sensor fibers; an apparatus for producing a sensor fiber; and a cross-sectional view of a target with an alternate arrangement of rings of carbonaceous material and rings of metal-containing material.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows a perspective view of a section of a sensor fiber with partially cut out layers. The sensor fiber 1 has a fiber core 2 which is formed of an electrically non-conductive (insulating) material. For example, as the fiber core 2, a commercially available glass fiber or a commercially available optical waveguide, for. B. with a

Diameter between 50 and 500 μηι, in particular 125 μηι be used. Conventional glass fiber materials as material for the fiber core 2 also have an enormously high tensile strength of about 3,500 N / mm ² , which corresponds to a significantly higher value than, for example, with metallic sensor fibers. The modulus of elasticity is comparable to that of aluminum at approx. 70,000 N / mm ² . The elongation at break is very high at 3 to 4%. Alternatively, the fiber core 2 may be formed with non-conductive aramid or ceramic fibers.

On the fiber core 2, a sensor layer 3 is applied as a thin film. In the exemplary embodiment shown, the sensor layer 3 surrounds the fiber core 2 completely. Alternatively, the sensor layer 3 can only partially surround the fiber core 2.

The sensor layer 3 comprises a carbonaceous material having diamond-like carbon, graphitic carbon, amorphous carbon a-C or amorphous hydrocarbon a-C: H. The carbonaceous material of the sensor layer 3 forms a so-called carbon matrix into which clusters 4 of a conductive carbon

Cluster material are embedded. The clusters 4 represent islands of the cluster material or of a carbide of the cluster material in the carbon-containing layer and are preferably uniformly distributed in the sensor layer 3.

FIG. 2 shows a section of a cross-sectional view in the radial direction through the sensor fiber 1. The clusters 4 may be in spherical or irregular form, which are surrounded by a carbon matrix of the sensor layer 3. During production, with a variation of process parameters, elliptical and elongated forms of cluster 4 were also observed. It has been found that the shape of the clusters 4 does not significantly affect the function of the sensor layer 3. The cluster material is embedded in the carbonaceous sensor layer 3. The conductive material of the cluster 4 preferably contains a metal or a

Metal alloy, nickel, nickel alloys, nickel compounds, cobalt, cobalt alloys, cobalt compounds, iron, iron alloys or

Iron compounds are suitable and in particular nickel or nickel alloys are particularly suitable. In particular, as the cluster material, a material should be selected in which substantially no diffusion movement of the clusters and / or the cluster material occurs in the carbonaceous material. The clusters 4 formed of the cluster material are embedded in the carbonaceous material so that they are not in contact with each other. The transition between the clusters 4 to the carbonaceous material of the sensor layer 3 may be immediate or in the form of a shell 5 surrounding the cluster, such as a graphite shell, a graphene shell with one or more graphene layers or segments of graphite or graphene layers curved around the shell Cluster 4 are arranged to be formed. Graphite and graphene are manifestations of carbon. In graphene, the carbon atoms are honeycomb-bound, so that two-dimensional structures are formed.

The carbonaceous material separates the clusters 4 in the sensor layer 3 from each other and prevents percolation or clustering of the clusters 4, which can lead to the formation of a conductive path through the carbon-containing sensor layer 3. The proportion of the cluster material is preferably selected to be below a so-called percolation threshold for the cluster material in the carbonaceous material so that complete percolation of the clusters 4 in the carbonaceous material does not occur.

In order to provide the sensor fiber 1 with a defined temperature coefficient, a material having a positive temperature coefficient of electrical resistance is to be selected as the conductive cluster material. Thus, the strongly negative temperature coefficient of the resistance of the carbonaceous sensor layer 3 can be determined by the positive temperature coefficient of resistance of the sensor

Cluster material can be compensated. In particular, the proportion of the cluster material in the carbon-containing layer can be adjusted so that the

Temperature coefficient of electrical resistance of the sensor fiber is zero.

An important prerequisite for the linear temperature dependence is that when the material nickel is used as the cluster material, nickel is present in a thermodynamically stable phase in the clusters 4. Depending on the manufacturing method for the sensor layer 3, it may happen that nickel forms the metastable phase Ni ₃ C or Ni (hexagonal) with carbon. These phases are thermally unstable and can be slow and uncontrolled in the thermodynamically stable Convert cubic (fcc) phase, whereby the resistance of the sensor layer 3 thus formed changes permanently.

The sensor layer 3 of the sensor fiber 1 may be surrounded by an insulating layer 6, the z. B. is formed by applying a non-conductive resist. The insulating layer 6 serves to provide mechanical protection and protection against atmospheric moisture and liquid media. The insulating layer 6 further serves for electrical insulation of the sensor layer 3. As shown in a further embodiment of Figure 3, a further enclosure may be provided in the form of a conductive shield 7, the

Insulation layer 6 surrounds. The shield 7 may be provided as a metal mesh or metallic coating on the insulating layer 6. The shield 7 can serve, for example, to protect the sensor fiber 1 against electromagnetic radiation and thus to keep the measuring signal without interference, in particular with long sensor fibers 1.

The sensor fiber 1 can be used to measure various forces or torques. For example, a particularly high sensitivity can be achieved with an expansion or compression of the sensor fiber. In one example of a sensor fiber 1, the ohmic resistance of the sensor layer 3 at a length of 10 cm is about 10 kQ. When the fiber is stretched by 0.4%, the resistance changes by 10%, which corresponds to a k-factor of 25. In addition, the sensor fiber 1, in contrast to conventional sensor fibers, a sensitivity to pressures of the surrounding the sensor fiber 1 medium. Furthermore, the sensor fiber 1 makes it possible to detect a twist by its structure, since the strain-sensitive layer surrounds the non-conductive fiber core and thus is stretched at a twist.

FIG. 4 shows an example of the use of the sensor fiber 1. The sensor fiber 1 is contacted at two opposite ends by the Insulation layer 6 is removed, so that the active sensor layer 3 is exposed. The sensor layer 3 is surrounded by an electrically conductive contact ring 8, which contacts the sensor layer 3 in full to ensure the most uniform possible current distribution. The contact ring 8 is connected via a conductor connection with a measuring device 9 for measuring the electrical resistance. Other variants of the contacting of the sensor layer 3, such as by simple contact surfaces are possible.

In a further variant of the sensor fiber 1, the fiber core may also be formed with an electrical conductor which is insulated on its lateral surface. The electrical conductor can be used, for example, as a metallic wire, for. Example of nickel, platinum, steel or other metal or conductive material, be formed, which is circumferentially provided on its lateral surface with a suitable insulation. The insulation may include, for example, polyimide or ceramic. Otherwise, a fiber core formed in this way can be provided, as described above, with the sensor layer 3 and, if necessary, with the insulation layer e and possibly the shield 7. The insulation of the electrical conductor of the fiber core is to be provided so that a short circuit between the electrical conductor and the sensor layer 3 is excluded.

The electrical conductor inside the fiber core may be formed of a metal or other material having a very high temperature coefficient. For example, nickel is suitable for use as an electrical conductor with a temperature coefficient of about 6,000 ppm / K. When using the sensor fiber 1 in a sensor element, the sensor fiber 1 can be contacted both on the sensor layer 3 and on the electrical conductor inside the fiber core. The contacting can take place, for example, at the same positions at which the sensor layer 3 is contacted. In this way, the sensor fiber 1 can be used both for strain measurement or for measuring a compression, twisting or bending, as well as for measuring the temperature at the exact location of the strain measurement. As a further possibility results in the exclusive use as a strain sensor the ability to contact the sensor fiber only on one side electrically. It is at a position of the sensor fiber 1, z. B. at a first end, an electrical connection between the sensor layer 3 and provided in the fiber core electrical conductor. At another position, eg. B. at an opposite end, the electrical conductor of the fiber core and the sensor layer 3 are contacted separately and thus represent the contacts for a formed by the sensor fiber 1 sensor element.

One possible use of the sensor fiber 1 is to weave it into a textile fabric, fabric or the like, where the sensor fiber 1 can serve as a sensor unit for various deformations of the fabric or on the fabric acting pressures due to their abovementioned properties. Sensor fibers 1 may be provided individually or at a plurality of predetermined distances from each other in the fabric. The sensor fibers may be provided in different extents in the fabric to detect tensile loads in multiple directions. As a possible field of application, a textile fabric provided with one or more sensor fibers may be used to cover a seat for a motor vehicle or the like, e.g. B. to detect an occupancy of the seat and in particular to record an indication of a weight of the person sitting on the seat.

Another application is shown in FIG. Figure 5 shows a pressure vessel 20 which is wrapped with the sensor fiber 1, so that the sensor fiber 1 rests against the outer container surface. Due to the insulating layer 6 of the sensor fiber 1, it is not necessary to electrically isolate the pressure vessel 20 before it is wrapped with the sensor fiber 1. If the pressure of a medium in the interior of the pressure vessel 20 increases, the volume is increased by a corresponding deformation (expansion) of the container and the sensor fiber 1 is stretched. The elongation of the sensor fiber 1 can, as described above, be detected by a change in the ohmic resistance of the sensor fiber 1. Thus, the

Arrangement of Figure 5 is a way to measure the pressure of media in pressure vessels. Alternatively, an insulating layer on the surface of the Pressure vessel 20 may be arranged around which the sensor fiber 1 is wound. The sensor fiber 1 used can then be provided without insulation layer 6, as long as adjacent turns do not abut each other and thereby contact electrically.

According to a further embodiment, which is shown schematically in Figure 6, in the arrangements described above can be applied directly to the

Sensor layer 3 in sections, one or more conductor layers 16 are applied from an electrically conductive material, so that the sensor fiber 1 is sensitive only to a strain in sensor sections 17. The

Strain-sensitive sensor sections 17 of the sensor fiber 1 are then provided in the areas which are not covered by the conductor layers 16. In this way, the electrical resistance of the sensor fiber 1 can be lowered, so that even long sensor fibers 1 with lengths of several meters are suitable for use in a sensor element 1. Thus, the problem can be avoided, that with a very long sensor fiber 1, the resistance of the

Sensor layer 3 is too large and can no longer be measured with the desired accuracy due to the low currents. By selecting the positions and lengths of the conductor layers 16 provided in sections, those portions of the sensor fiber 1 can be selected in which the deformation of the sensor fiber 1 is to be evaluated integrally. Alternatively, with appropriate contacting of the conductor layers 16, a partial evaluation of the individual sensor sections 17 is possible. Also, the fiber core 2 of the sensor fiber 1 can be generally provided as a glass fiber, which can also be used as an optical waveguide for information transmission. As a result, combination sensors are possible, which on the one hand detect the above-described resistance change of the sensor layer 3 and on the other hand use physical influences on the light propagation in the fiber core 2. For example, in this way, the elongation of the sensor fiber 1 and the temperature of the sensor fiber 1 can be detected separately from each other. FIG. 7 shows a sensor element 10 for the easier handling of a sensor in the form of a sensor formed with one of the sensor fibers 1 described above

Strain gauge. The sensor element 10 has a flexible

Carrier substrate 1 1 (substrate), in particular of a flexible

(electrically non-conductive) plastic material. On the carrier substrate 1 1, a sensor fiber 1 is applied. The sensor fiber 1 is fixed either with a suitable adhesive on the carrier substrate 1 1 or embedded between the flexible carrier substrate 1 1 and a cover layer (not shown), which simultaneously protects the sensor fiber 1 from external influences. The sensor fiber 1 is contacted at the ends via contact surfaces 12. The sensor fiber 1 is in the

Embodiment of FIG. 7 arranged substantially straight on the substrate 1 1. For use as a strain sensor, the substrate 1 1 is applied flat to a device, for. B. glued, so that a bending or stretching of the component to a corresponding elongation (or compression) of the sensor element 10 leads. This can then be determined by a measurement of

Conductivity or electrical variables dependent thereon are determined.

As shown in FIG. 8, a sensor element can also be provided with a meander-shaped sensor fiber 1 on the carrier substrate 11. Preferably, the contact surfaces 12 are then arranged on one side or next to each other in order to simplify the contacting of the sensor element.

In the embodiments of the strain gauge, the sensor fiber 1 can also be arranged between the carrier layer 1 1 and a top layer applied shear-resistant thereto. The material of the carrier substrate 1 1 and, if present, the cover layer may be provided so that this one

Length change of the sensor fiber 1 no significant resistance

oppose. Preferably, the elasticity of the carrier substrate 11 or the composite of the carrier substrate 11 and the cover layer is 10 to 20 times greater than the elasticity of the sensor fiber 1 in order to reduce the influence on the strain of the sensor fiber 1. The result is a robust and easy-to-handle flexible sensor element 10, with which integral strains can be measured over short as well as longer sections. Alternatively, if the sensor fiber 1 is provided with the non-conductive insulation or protective layer 6, the carrier substrate 11 and / or the cover layer may also be provided in a conductive manner, eg as a metallic layer. Due to the rigidity of metallic layers, additional protection of the sensor fiber 1 against overstretching during assembly and operation can generally be achieved.

FIG. 9 shows a further embodiment of a sensor element 20 in which a plurality of sensor fibers 1 are applied essentially parallel to the carrier substrate 11. The carrier substrate 1 1 is provided substantially band-shaped and provided at one end with a Kontaktierungsleiste 13, via which the individual sensor fibers 1 can be contacted. The contacting strip 13 has conductive contact surfaces 12 for this purpose. In each case two of the sensor fibers 1 are connected to one another by means of an electrically conductive bridge 15 at a predetermined position on the carrier substrate 1 1. Such a sensor element 10 can be produced in a simple manner by automated application of the sensor fibers 1 to the carrier substrate 11.

The sensor element of Figure 9 offers the possibility, depending on the selection of

Contact surfaces 12 for measuring the sensor signal to determine the bending or elongation integrally over different length ranges starting from the contact strip 13.

Within a range between the two bridges 15 on the carrier material 1 1, the sensor element 10 can be separated, the length of the

Is available sensor area indicated by those contact surfaces 12, between which there is an electrically conductive connection. If the resistance between two contact surfaces 12 has a high impedance, then these are connected to those sensor fibers 1 whose bridges 15 have been cut off by shortening the carrier substrate 11 to a specific length. In this way, by measuring the electrical resistances between the

Contact surfaces the actual used length of the sensor element 10 are determined. Since sensor fibers 1 can be produced as a rule as an endless sensor fibers, the production of sensor elements 10, as shown in Figures 7, 8 and 9, can be realized in a simple manner.

The sensor fiber 1 can be produced by means of a device 30, which is shown schematically in FIG. The device 30 comprises a vacuum chamber 35, in which a coating device 36 is arranged. This will be a

Glass fiber 2 as a fiber core from a source spindle 31 through a tubular target 32, e.g. a nickel target, guided at a predetermined, preferably constant speed and wound as a coated sensor fiber 2.3 on a target spindle 33. The source spindle 31, the tubular nickel gate 32 and the target spindle 33 are located in the vacuum chamber 35. The coating takes place in a vacuum chamber 35

Coating chamber 34, in which the glass fiber 2 in a low-pressure atmosphere of a protective gas or an inert gas, such as. As argon, and a

carbonaceous gas, such as. Ethene, through the tubular nickel target 32. The proportion of the carbon-containing gas with respect to the protective gas is between 1% and 5%.

In the coating chamber 34, a plasma process is ignited, wherein the material of the tubular target 32 is removed. This will be the

Glass fiber 2 homogeneously coated by a combined sputtering and gas phase deposition process, forming a carbonaceous layer in which are embedded separate clusters of conductive material. The coated sensor fiber 2, 3 is then present on the target spindle 33 and can be removed from the coating chamber 34 and further processed. For example, the protective layer 6 and / or the shield 7 can be applied in subsequent processes.

The thickness of the sensor layer 3 may be determined by the power of the plasma process and / or by the speed at which the fiber core 2 passes through the plasma tubular target is guided, can be adjusted. Also, by negatively biasing the target spindle 33 or an output side portion of the manufactured sensor fiber 1, the sputtering process can be performed as a so-called bias sputtering, which improves the film characteristics of the applied sensor layer.

Alternatively, for producing a metal-containing carbon sensing layer, i. a sensor layer containing no hydrogen may be provided that the target 32 for a PVD process comprises a metal and carbonaceous material. An example of such a target 32 is shown in FIG. 11. The target 32 may be annular, in the axial direction, e.g. alternately arranged metal discs 38 and graphite discs 37 and metal and

Graphite rings are formed, which together form the tubular target 32. The thicknesses of the individual metal 38 and graphite disks 37 determine the

Composition of the sputtered layered material, i. the proportion of the carbonaceous material to the cluster material. As the gas atmosphere, pure inert gas, such as e.g. Argon, without the addition of one

carbonaceous gas used. If nickel rings and graphite rings 37 are used for the target 32, then a carbon-containing sensor layer with nickel clusters is formed.

Claims

1 . Sensor fiber (1) for measuring deformation, comprising:

- A non-conductive at least on its lateral surface fiber core (2);

a sensor layer (3) surrounding the fiber core (2);

wherein the sensor layer (3) contains a carbonaceous material in which clusters (4) of conductive cluster material are embedded, the clusters (4) being separated from each other by the carbonaceous material.

2. sensor fiber (1) according to claim 1, wherein the fiber core is formed entirely of an electrically non-conductive material or one at its

Lateral surface comprises insulated electrical conductors.

3. sensor fiber (1) according to claim 1 or 2, wherein the sensor fiber (1) comprises a sensor layer (3) surrounding non-conductive layer (6), which serves as an insulating layer and / or protective layer.

4. sensor fiber (1) according to one of claims 1 to 3, wherein the sensor fiber (1) comprises a sensor layer (3) surrounding electrically conductive shield (7).

5. sensor fiber (1) according to one of claims 1 to 4, wherein the sensor fiber (1) comprises a plurality of sensor sections (17) which are defined by at least one electrically conductive conductor layer (16) in a region of the sensor fiber (1) directly is applied to the sensor layer (3).

6. Sensor element comprising:

- A carrier material (1 1);

- At least one sensor fiber (1) according to one of claims 1 to 5, which is applied to the carrier material (1 1) or introduced into the carrier material (1 1).

7. Sensor element according to claim 6, wherein contact surfaces (12) for

Contact the sensor fiber (1) are provided.

8. Sensor element according to claim 7, wherein the carrier material (1 1) with

a plurality of parallel sensor fibers (1) is provided, wherein the contact surfaces for contacting the individual sensor fibers (1) on a contact strip (12) at one end of the carrier material (1 1) are arranged, wherein between each two of the sensor fibers (1) at different

Positions along the extension of the sensor fibers (1) in the

Support material electrically conductive connections (15) are arranged.

9. Textile fabric with one or more sensor fibers (1) according to one of claims 1 to 5.

10. A method of manufacturing a sensor fiber (1) according to any one of claims 1 to 5, wherein a PVD process with a sputtering material of a

tubular target (32) is performed on a fiber core (2) under a reactive atmosphere of a carbonaceous gas containing, in particular, ethane, ethene or ethyne, so that the carbonaceous gas dissociates and a carbonaceous layer is deposited on a surface of the fiber core (2) is embedded in the clusters (4) of the sputtering material, the fiber core being passed through a tubular target while it is being coated.

1 1. A method of manufacturing a sensor fiber (1) according to any one of claims 1 to 5, wherein a PVD process is performed from a tubular target (32) of carbonaceous material and metal-containing material to a fiber core (2) under a non-reactive atmosphere of an inert gas so that a carbonaceous layer from the

Carbonaceous material is deposited on a surface of the fiber core (2) embedded in the clusters (4) of the metal-containing material with the fiber core (2) being passed through a tubular target (32) while it is being coated.

12. The method of claim 1 1, wherein the target of each other,

in particular alternately, mounted rings (37, 38) is formed from the carbonaceous material and from the metal-containing material.

13. The method according to any one of claims 10 to 12, wherein the fiber core (2) during the PVD process to a temperature below 600 ° C,

in particular to a temperature between 150 ° C and 300 ° C, is heated.

14. The method according to any one of claims 10 to 13, wherein the PVD process is carried out in a coating chamber (35), wherein the sensor fiber (1) at or behind the output of the coating chamber (35) is connected to a negative bias voltage, so that the portion of the sensor fiber (1) located inside the coating chamber (35) is electrically biased to perform bias sputtering.