Sensor device for determining hydrogen concentration in environment of sensor device

Abstract

The invention relates to a sensor device (100, 200, 300, 400, 500, 600, 700) for determining a hydrogen concentration in the environment of the sensor device (100, 200, 300, 400, 500, 600, 700), the sensor device (100, 200, 300, 400, 500, 600, 700) having a substrate (110, 210, 310, 410, 510, 610, 710) and a measuring structure (120, 220, 320, 420, 520, 620, 720) which is at least partially palladium-containing and which can be electrically contacted by means of a contact conductor circuit (130, 230, 330, 430, 530, 630, 730) and is arranged on the substrate (110, 210, 310, 410, 510, 610, 710), the measuring structure (120, 220, 320, 420, 520, 620, 720) is arranged such that more than 60%, in particular more than 80%, of the surface of the measuring structure (120, 220, 320, 420, 520, 620, 720) is exposed, and wherein the sensor device (100, 200, 300, 400, 500, 600, 700) is designed to detect an electrical measurement variable of the measuring structure (120, 220, 320, 420, 520, 620, 720) and to determine the hydrogen concentration on the basis of the detected electrical measurement variable.

Description

Technical Field

[0001] The invention relates to a sensor device for determining a hydrogen concentration in an environment of the sensor device. Background Art

[0002] With the increasing use of hydrogen-based systems (such as hydrogen fuel cells), the demand for hydrogen sensor devices used to monitor these systems is increasing. For example, hydrogen leaks need to be detected promptly to prevent or warn of the development of explosive gases. This creates a need for reliable and fast hydrogen sensor devices that measure hydrogen concentration in air or other media.

[0003] Existing sensor devices on the market use different measurement principles. For example, there are electrochemical cells, catalytic oxidation sensors (Pellistor), metal oxide gas sensors, thermal conductivity sensors, and sensors that exploit the changes in the physical properties of palladium or palladium alloys when storing hydrogen. However, all currently available sensors suffer from shortcomings related to at least one of the following parameters: sensitivity, transverse sensitivity to other gases, dynamic measurement range, response time, cost, specificity, media robustness, or service life. This limits the use of these sensors.

[0004] Prior art hydrogen sensor devices, for example, can use changes in the electrical properties of palladium or a palladium alloy when hydrogen is stored as a signal for measuring the hydrogen concentration in the medium. It is known that the electrical resistance of palladium changes or increases when hydrogen is stored. This effect is used to measure the hydrogen concentration in the surrounding environment. MEMS sensor devices utilizing this measurement principle typically use a planar palladium-containing measuring structure formed from a thin palladium-containing layer on a substrate. This measuring structure is contacted via other metallic conductors and transmits the signal externally. A problem with this is that, because the measuring structure is planarly attached to the substrate, only a small portion of the measuring structure's surface is in contact with the gas in the sensor device's environment. This limits the sensor device's response time. Prior art also uses an adhesive layer or palladium-containing alloy to prevent the measuring structure from loosening from the surface during its service life due to humidity, temperature changes, and / or hydrogen storage and the resulting stress changes in the layer. This reduces sensitivity due to parasitic parallel resistance.

[0005] The aforementioned problems in the prior art are to be solved primarily by means of the present invention. Summary of the Invention

[0006] The present invention relates to a sensor device for determining the hydrogen concentration in an environment of the sensor device, wherein the sensor device comprises a substrate and a measuring structure composed at least partially of a palladium-containing material, the measuring structure being electrically contactable via a contact conductor track and being arranged on the substrate in such a way that more than 60%, in particular more than 80%, of the surface of the measuring structure is exposed, wherein the sensor device is designed to detect an electrical measurement variable of the measuring structure and to determine the hydrogen concentration as a function of the detected electrical measurement variable.

[0007] Advantageously, the exposure of the measuring structure improves the response time and sensitivity of palladium-based hydrogen sensor devices, which can measure changes in the electrical properties of the palladium-containing measuring structure when hydrogen is stored. Unlike MEMS sensor devices in the prior art, a large portion of the surface of the palladium-containing measuring structure is exposed, allowing the measuring structure to be in contact with the medium to be measured or to flow around it over a large area, in particular from all sides. This accelerates the storage and extraction of hydrogen in the measuring structure and shortens the response time of the sensor device, which can result in higher sensitivity, media robustness, service life, and / or shorter response times.

[0008] Furthermore, in the case of a heated resistance structure, heat dissipation during operation, for example into the substrate, and thus power consumption, can be reduced.

[0009] Furthermore, by appropriately configuring the measuring structure as a suspended structure, a corresponding adhesion layer between the substrate and the measuring structure can be largely omitted. Alternatively, the adhesion layer can be provided only in the areas where the measuring structure is mechanically fastened to the substrate and / or where an electrical connection is established between the measuring structure and the contact conductors. This prevents material from the adhesion layer from diffusing extensively into the palladium-containing resistor structure at higher temperatures and causing undesirable effects. Furthermore, the absence of an adhesion layer improves dielectric robustness. Influences on the measurement signal due to corrosion of the adhesion layer do not occur. Furthermore, this novel concept allows for greater freedom in the material composition and layer thickness of the palladium-containing structure.

[0010] Furthermore, the exposure reduces the stress sensitivity of the sensor signal, since no or only minor stress-induced effects in the measuring structure have an influence on the sensor signal.

[0011] In this case, the sensor device can be designed in particular as a MEMS component. In this case, the environment is the surroundings of the sensor device, which comprises, for example, a medium or air and is to be monitored by means of the sensor device.

[0012] The palladium-based sensor device proposed herein uses changes in the electrical properties of palladium or a palladium alloy when hydrogen is stored as a signal for measuring the hydrogen concentration in the medium. To this end, the measuring structure is configured at least regionally as a palladium-containing conductor track and is indirectly or directly arranged on or connected to a substrate and electrically contacted via a contact conductor track. For example, the resistance value determined at least regionally and / or the resistance change determined at least regionally of the measuring structure can be understood as an electrical measurement variable. Ideally, a four-point measurement is used for the resistance measurement of the palladium-containing measuring structure so as to be independent of the contact resistance and / or lead resistance (Zuleitungswiderstand) and their changes. This also applies in particular to changes in the contact resistance and / or the leads caused by hydrogen.

[0013] Here, the substrate serves as a carrier for the measuring structure and enables rapid and simple production of the sensor device. For example, the substrate can be configured as a wafer and, for example, comprise silicon and / or at least one other material and / or also a combination of materials.

[0014] For example, a substrate may also be understood to be a carrier composed of silicon and / or glass, which carrier comprises at least one dielectric layer. In particular, a substrate may also have a plurality of dielectric layers and form a corresponding layer system.

[0015] Additionally or alternatively, the substrate can include a plurality of conductor tracks.

[0016] Additionally or alternatively, the substrate may also include integrated circuits and / or MEMS components.

[0017] For example, the contact conductor track can be designed as a foil conductor structure or in a layered manner and consist of a material that is both electrically and thermally conductive, for example Al, AlCu and / or Pt and / or Au.

[0018] Bare is to be understood as meaning that the surface of the measuring structure is not in direct contact with the substrate or other components of the sensor device over the entire surface, at least in regions, but rather that the measuring structure can be surrounded by a medium whose hydrogen concentration is to be detected.

[0019] One embodiment of the invention provides that the measuring structure is essentially completely exposed.

[0020] The advantage here is that the almost complete exposure of the measuring structure creates a surface that is as large as possible and can interact with the medium in the environment of the sensor device. If hydrogen is present in this environment, it can thus come into contact with the measuring structure in an intensive manner, thereby reducing the reaction time of measurements performed by the sensor device.

[0021] Essentially bare is to be understood as meaning that the complete surface of the measurement structure is almost bare and, for example, only a region of the measurement structure is still in contact with the substrate and / or contact conductor tracks serving as a carrier and / or electrical contacting possibility.

[0022] One embodiment of the invention provides that the measuring structure is arranged on the substrate by means of at least one distance element and / or by means of at least one dielectric layer, the distance element being in particular in the form of a contact conductor track and / or being formed from the material of the contact conductor track.

[0023] It is advantageous here that the substrate does not need to be processed or only needs to be processed insignificantly, and for example existing contact conductor tracks can be used as distance elements in order to leave the measuring structure exposed.

[0024] The distance element ensures that the measuring structure does not rest directly on the substrate, but is arranged at a distance from it, in order to allow the measuring structure to be exposed.

[0025] The dielectric layer system can, for example, be constructed from a plurality of individual layers made of the same material and / or different materials, which are in turn structured accordingly. In particular, contact conductor circuits, for example for the electrical attachment of the measuring structure, can be integrated into the layer system. In this case, the measuring structure at least partially penetrates the layer system and uses at least some areas of the layer system as a carrier.

[0026] Another embodiment of the invention provides that the substrate has a recess below the measuring structure, which extends at least partially through the substrate.

[0027] The advantage here is that, in principle, the measuring structure can be utilized as in the prior art and its exposure can be achieved by providing corresponding cutouts in the substrate or in a deposited layer of the substrate.

[0028] In particular, the recess is located on the upper side of the substrate and can be configured as a trench or blind hole-shaped structure, for example. However, in principle, the recess can also extend up to the lower side of the substrate.

[0029] A trench is understood to be a depression which is introduced into the substrate surface and which has an elongated hole-shaped structure on the substrate surface.

[0030] According to another embodiment of the invention, the measuring structure is designed in an arcuate and / or stepped and / or meandering manner in a plane perpendicular to the main extension plane of the substrate and / or in a plane parallel to the main extension plane of the substrate.

[0031] Advantageously, due to the corresponding design, stresses along the main extension of the measuring structure and therefore parallel to the substrate, which stresses are generated, for example, by hydrogen storage or by corresponding temperature profiles acting on the sensor device and the associated thermally induced length changes of the measuring structure, can be reduced. As a result, the sensor device can be more robust and less prone to errors.

[0032] In this case, the measuring structure can have any desired distance from the substrate, depending on requirements and spatial availability.

[0033] According to another embodiment of the invention, the ratio of the height to the width of the cross section of the measuring structure is greater than 1:1, in particular greater than 2:1, particularly preferably greater than 4:1. In other words, the height of the measuring structure is greater than the width, so that even if the measuring structure is not completely exposed and is mechanically attached at least in areas to the dielectric layer system, at least 75% (1:1), 83% (2:1), or 90% (4:1) of the surface is exposed to the surrounding environment.

[0034] The advantage here is that a large area of ​​the measuring structure can be exposed without requiring significant modifications to the substrate or the measuring structure compared to the prior art. Furthermore, compared to a measuring structure that is not etched from below and in which diffusion occurs essentially only from the surface of the measuring structure, the exposed measuring structure advantageously reduces the time constant until a saturated measured value is reached by almost half, due to, for example, the comprehensive surface diffusion of hydrogen into the measuring structure.

[0035] In this case, the cross-section of the measuring structure can have a height of, for example, greater than 2 μm, relative to a width of less than 500 nm. The term "height" is understood to mean the extent of the measuring structure, i.e., the distance between the upper side of the measuring structure facing away from the substrate and the lower side facing the substrate. The term "width" is understood to mean the extent of the measuring structure parallel to the substrate surface, i.e., the distance between one side of the measuring structure and the opposite side, oriented perpendicularly to the main extension direction of the measuring structure and orthogonal to the height of the measuring structure.

[0036] In this case, the measuring structure can be arranged, for example, on a membrane, in particular a membrane of a substrate, or on a separate substrate or also in a suspended manner.

[0037] In particular, such a measuring structure is configured as a suspended conductor track and is manufactured by applying a sacrificial layer etching process, which is carried out, for example, as follows. First, a substrate is provided, which already has, for example, a heating element and a conductor track that at least contacts the heating element. The conductor track can be arranged at least regionally on and / or in a dielectric layer or on and / or in a dielectric layer system. Next, a sacrificial layer is applied and structured to obtain a tab-shaped sacrificial structure. A palladium-containing layer is then applied or deposited onto the substrate having the structured sacrificial layer. In a subsequent step, the palladium-containing layer is structured so that a measuring structure is constructed that is at least regionally located on the substrate and / or on the dielectric layer system constructed on the substrate and extends at least regionally over the tab-shaped sacrificial structure. Then, in a final step, the sacrificial layer is selectively removed relative to the measuring structure and the substrate and / or the dielectric layer system constructed on the substrate to obtain the final sensor device.

[0038] According to a further embodiment of the invention, a heating element is arranged at least regionally below the measuring structure, in particular a heating element embedded in at least one dielectric layer.

[0039] Advantageously, the response time of the measuring structure, for example in detecting hydrogen, is reduced when the measuring structure is operated at an increased temperature. This temperature increase can be easily achieved by the heating element without thereby reducing the robustness of the sensor device.

[0040] According to a further embodiment of the invention, the sensor device has a plurality of measuring structures which are arranged adjacent to one another.

[0041] It is advantageous here that an array arrangement can be achieved by means of a plurality of measuring structures, whereby the signal-to-noise ratio can be improved and the measuring resistance of the sensor device can be adjusted.

[0042] According to one embodiment of the invention, the measuring structure comprises essentially palladium.

[0043] It is advantageous here that no parallel resistances are generated by other materials in the sensing region of the measuring structure, which could falsify the measurement result.

[0044] Essentially comprising palladium is to be understood as meaning that the measuring structure comprises only palladium apart from possible process-related impurities or functional-related additives consisting of other chemical substances and / or elements.

[0045] According to another embodiment of the invention, the measuring structure has a passivation layer on the surface at least in regions, which is preferably only permeable to hydrogen. In the case of a bare structure, the bare structure should be covered by the passivation layer in the sensing region or in the exposed region.

[0046] Advantageously, the passivation layer protects the measuring structure, for example, from external chemical influences while nevertheless allowing the hydrogen gas to be detected to enter the measuring structure. In particular, the passivation layer also achieves selectivity with respect to other gases, since gases other than hydrogen are poorly or completely unable to penetrate the passivation layer. This prevents distortion of the measurement results by other gases in the sensor device's surroundings, protects against leakage flows caused by particles or humidity, and achieves high long-term stability of the measuring structure.

[0047] The passivation layer can be, for example, a nitride passivation, for example a nitride passivation composed of silicon nitride. Alternatively or additionally, silicon oxide and / or aluminum oxide can also be used as the passivation layer.

[0048] According to a further embodiment of the invention, the sensor device comprises a cap element having at least one cutout, wherein the measuring structure is arranged between the cap element and the substrate.

[0049] Advantageously, the cover element protects the measuring structure from external influences, particularly mechanical influences or light penetration, as well as from particles, and the hydrogen to be detected can be passed through the slit in the cover element to the measuring structure. The arrangement between the cover element and the substrate ensures that the measuring structure itself is fully protected. Furthermore, in the presence of a flammable gas mixture, the slit-equipped cover element prevents the spread of a flame front and provides explosion protection.

[0050] A slit can be understood, for example, as a hole or a channel which, after the cover element is connected to the substrate, connects the inner side of the cover element facing the substrate with the outer side of the cover element facing away from the substrate and can serve as a gas inlet to the intermediate space and / or cavity created between the cover element and the substrate.

[0051] In particular, the cap element can also have a cavity, which can, for example, contribute to a lower heat dissipation in the region of the heated measuring structure.

[0052] According to a further embodiment of the invention, it is provided that at least one breach is closed by means of an element which is preferably permeable only to hydrogen.

[0053] Advantageously, a suitable configuration of the aperture allows selectivity with respect to other gases to be achieved, and gases other than hydrogen are only poorly or not able to penetrate the hydrogen-permeable element, thereby reducing or completely preventing distortion of the measurement results by other gases in the surroundings of the sensor device. Furthermore, the measuring structure can be protected from other external influences, such as moisture and liquid media.

[0054] The hydrogen-permeable element can be designed, for example, as a membrane composed of silicon dioxide and / or palladium. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1a and Figure 1b A first exemplary embodiment of the sensor device according to the invention is shown both in a lateral sectional view and in a plan view.

[0056] Figure 2a and Figure 2b A second exemplary embodiment of the sensor device according to the invention is shown both in a lateral sectional view and in a plan view.

[0057] Figure 3 A third exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0058] Figure 4 A fourth exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0059] Figure 5a and Figure 5b A fifth exemplary embodiment of the sensor device according to the invention is shown both in a lateral sectional view and in a plan view.

[0060] Figure 6 A sixth exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0061] Figure 7a and Figure 7b A seventh exemplary embodiment of a sensor device according to the invention is shown both in a lateral sectional view and in a plan view. DETAILED DESCRIPTION

[0062] Figure 1a and Figure 1b A first exemplary embodiment of the sensor device according to the invention is shown both in a lateral sectional view and in a plan view. Figure 1a The cross-sectional view here involves Figure 1b Section A shown.

[0063] The present invention shows a sensor device 100 for determining the hydrogen concentration in the environment of the sensor device 100. The sensor device 100 comprises a substrate 110 and a measuring structure 120 containing at least partly palladium, which can be electrically contacted via contact conductor tracks 130 and is arranged on the substrate 110 such that more than 60%, in particular more than 80%, of the surface of the measuring structure 120 is exposed.

[0064] In particular, the measuring structure 120 is essentially completely exposed and has, at least in a starting region and in an end region of the measuring structure 120, a mechanical contact with the substrate 110 and / or an electrical contact with a contact conductor track 130 electrically contacting the measuring structure 120. To achieve this exposure, the substrate 110 has a recess 112 extending at least partially through the substrate 110 below the measuring structure 120, whereby the measuring structure 120 is designed in a suspended manner, with the exception of at least one starting region and an end region of the measuring structure 120.

[0065] The measuring structure 120 essentially comprises palladium.

[0066] Furthermore, the measuring structure 120 may have, at least in regions on its surface, a passivation layer (not shown in the image) which is preferably permeable only to hydrogen.

[0067] Furthermore, sensor device 100 is configured to detect an electrical measurement variable of measurement structure 120 , for example, the resistance of measurement structure 120 , and to determine the hydrogen concentration as a function of the detected electrical measurement variable.

[0068] In an alternative, not shown, embodiment, the measuring structure 120 can, for example, also extend in a meandering manner in a plane parallel to the main extension plane of the substrate 110 , wherein, optionally, further regions / segments of the meandering structure can be mechanically and / or electrically connected to the substrate 110 and / or the contact conductor circuit 130 .

[0069] Figure 2a and Figure 2b A second exemplary embodiment of the sensor device according to the invention is shown both in a side sectional view and in a top view. Figure 2a The cross-sectional view involves Figure 2b Section B shown.

[0070] Sensor device 200 is shown for determining the hydrogen concentration in an environment of sensor device 200. Like sensor device 100, sensor device 200 essentially comprises a substrate 210 and a measuring structure 220 that at least partially contains palladium. This measuring structure can be electrically contacted via contact conductor tracks 230 and is arranged on substrate 210 such that more than 60%, in particular more than 80%, of the surface of measuring structure 220 is exposed. Sensor device 200 is also configured to detect an electrical measurement variable of measuring structure 220 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0071] However, sensor device 200 differs from sensor device 100 in that measuring structure 220 is arranged on substrate 210 by means of a spacer element which is formed at least in regions as a contact conductor track 230 and / or is formed in regions from the material of contact conductor track 230. Consequently, in sensor device 200, recess 112 in substrate 110 of sensor device 100 is not absolutely necessary, and therefore substrate 210 does not have a corresponding recess.

[0072] Figure 3 A third exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0073] Sensor device 300 is shown for determining the hydrogen concentration in an environment of sensor device 300. Like sensor device 200, sensor device 300 essentially comprises a substrate 310 and a measuring structure 320 containing at least some palladium. This measuring structure can be electrically contacted via contact conductor tracks 330 and is arranged on substrate 310 such that more than 60%, in particular more than 80%, of the surface of measuring structure 320 is exposed. Sensor device 300 is also configured to detect an electrical measurement variable of measuring structure 320 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0074] However, sensor device 300 differs from sensor device 200 in that measurement structure 320 is designed in a stepped manner in a plane perpendicular to the main extension plane of substrate 310. The stepped shape of measurement structure 320 is oriented away from the surface of substrate 310. At least the starting region and the end region of measurement structure 320 can have the same or different distances from the substrate surface.

[0075] In an alternative embodiment not shown in the image, in addition to or instead of the stepped configuration, the measuring structure can also be configured in an arcuate and / or meandering manner in a plane perpendicular to the main extension plane of the substrate 310, wherein additional mechanical contact structures and / or electrical contact structures can be constructed with the substrate 310 and / or with the contact conductor circuit 330 and / or with the structure composed of the material of the contact conductor circuit 330, and the distance between the mechanical contact structure and / or the electrical contact structure and the surface of the substrate 310 can correspond to the distance between the starting area and / or the end area of ​​the measuring structure.

[0076] Figure 4 A fourth exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0077] Sensor device 400 is shown for determining the hydrogen concentration in its environment. Like sensor device 300, sensor device 400 essentially comprises a substrate 410 and a measuring structure 420 containing at least some palladium. This measuring structure can be electrically contacted via contact conductor tracks 430 and is arranged on substrate 410 such that more than 60%, in particular more than 80%, of the surface of measuring structure 420 is exposed. Sensor device 400 is also configured to detect an electrical measurement variable of measuring structure 420 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0078] Like measuring structure 320 of sensor device 300, measuring structure 420 of sensor device 400 is designed in a stepped manner in a plane perpendicular to the main extension plane of the substrate, wherein in this variant, at least one step of measuring structure 420 is designed facing toward substrate 410, rather than being shown away from substrate 310 as shown in measuring structure 320. In this variant, the provision of a recess 412 in substrate 410 results in the uncovering of at least a region of measuring structure 420 having a stepped design in the direction of substrate 410.

[0079] Figure 5a and Figure 5b A fifth exemplary embodiment of a sensor device according to the invention is shown both in a side sectional view and in a top view. Figure 5a The cross-sectional view involves Figure 5b Section C shown.

[0080] Sensor device 500 is shown for determining the hydrogen concentration in an environment of sensor device 500. Like sensor device 200, sensor device 500 essentially comprises a substrate 510 and a measuring structure 520 containing at least some palladium. This measuring structure can be electrically contacted via contact conductor tracks 530 and is arranged on substrate 510 such that more than 60%, in particular more than 80%, of the surface of measuring structure 520 is exposed. Sensor device 500 is also configured to detect an electrical measurement variable of measuring structure 520 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0081] Sensor device 500 differs from sensor device 200 in that measurement structure 520 is arranged on substrate 510 using a dielectric layer system comprising at least dielectric layers 535 and 536. By partially removing dielectric layer 535 and optionally removing dielectric layer 536, measurement structure 520 can be provided in a suspended manner, at least in regions. Contact conductor tracks 530 for electrically attaching measurement structure 520 are arranged within dielectric layers 535 and 536 or at least partially surrounded by these layers. In this variant, the electrical connection between contact conductor tracks 530 and measurement structure 520 is achieved by providing contact hole structures in the region of contact conductor tracks 530 that penetrate dielectric layer 535. In particular, for example, the dielectric layer can be composed of a material containing at least one of the elements Si, Ge, Al, Ti, Ta, O, and N, such as SiO2 or Si3N4. In particular, the dielectric layer can optionally consist of a plurality of dielectric layers in order, for example, to be able to achieve at least locally a defined mechanical layer stress or a defined mechanical layer tension and / or a defined heat conduction.

[0082] Figure 6 A sixth exemplary embodiment of a sensor device according to the invention is shown in a sectional side view.

[0083] Sensor device 600 is shown for determining the hydrogen concentration in an environment of sensor device 600. Like sensor device 100, sensor device 600 essentially comprises a substrate 610 and a measuring structure 620 containing at least some palladium. This measuring structure can be electrically contacted via contact conductor tracks 630 and is arranged on substrate 610 such that more than 60%, in particular more than 80%, of the surface of measuring structure 620 is exposed. Sensor device 600 is also configured to detect an electrical measurement variable of measuring structure 620 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0084] Sensor device 600 differs from sensor device 100 in that it comprises a cap element 640 having at least one aperture 642, wherein measuring structure 620 is arranged between cap element 640 and substrate 610. In particular, at least one aperture 642 can be closed by an element 643, which is preferably permeable only to hydrogen.

[0085] Figure 7a and Figure 7b A seventh exemplary embodiment of a sensor device according to the invention is shown both in a side sectional view and in a top view. Figure 7a The cross-sectional view involves Figure 7b Section D shown.

[0086] Sensor device 700 is shown for determining the hydrogen concentration in an environment of sensor device 700. Like sensor device 100, sensor device 700 essentially comprises a substrate 710 and a measuring structure 720 that at least partially contains palladium. This measuring structure can be electrically contacted via contact conductor tracks 730 and is arranged on substrate 710 such that more than 60%, in particular more than 80%, of the surface of measuring structure 720 is exposed. Sensor device 700 is also configured to detect an electrical measurement variable of measuring structure 720 and to determine the hydrogen concentration based on the detected electrical measurement variable.

[0087] Sensor device 700 differs from sensor device 100 in that the ratio of height 722 to width 724 of measurement structure 720 is greater than 1:1, in particular greater than 2:1, and particularly preferably greater than 4:1. Furthermore, a heating element 740 is embedded at least regionally below measurement structure 720, for example, in at least one dielectric layer 735 of substrate 710, to enable efficient heating of the measurement structure and / or a rapid heating rate. Substrate 710 may further include a recess 712 below heating element 740, extending at least regionally into the substrate perpendicular to the main extension plane of substrate 710, to minimize heat dissipation into substrate 710. Furthermore, sensor device 700 may include a plurality of measurement structures 720, which are arranged adjacent to one another and optionally aligned in series and / or in parallel with one another on substrate 710.

[0088] Depending on requirements and technical possibilities, the above-described different embodiments or configurations of the present invention can also be combined accordingly.

[0089] Furthermore, it should be noted that in the embodiments or configurations described above, the measurement structure 120, 220, 320, 420, 520, 620, 720 can have any desired shape in a plane parallel and / or perpendicular to the main extension plane of the substrate 110, 210, 310, 410, 510, 610, 710, and that a plurality of measurement structures 120, 220, 320, 420, 520, 620, 720 can optionally be arranged on the substrate 110, 210, 310, 410, 510, 610, 710, thereby enabling a large sensing surface. Furthermore, by electrically interconnecting a plurality of measurement structures 120, 220, 320, 420, 520, 620, 720 in series and / or in parallel, the resistance of the resulting measurement structure can be adjusted.

Claims

1. A sensor device (100, 200, 300, 400, 500, 600, 700) for determining a hydrogen concentration in an environment of the sensor device (100, 200, 300, 400, 500, 600, 700), wherein: The sensor device (100, 200, 300, 400, 500, 600, 700) comprises a substrate (110, 210, 310, 410, 510, 610, 710) and a measuring structure (120, 220, 320, 420, 520, 620, 720) which contains palladium at least in part and can be electrically contacted via a contact conductor track (130, 230, 330, 430, 530, 630, 730) and is arranged on the substrate (110, 210, 310, 410, 510, 610, 710). 0, 510, 610, 710), so that more than 60%, in particular more than 80%, of the surface of the measuring structure (120, 220, 320, 420, 520, 620, 720) is exposed, wherein the sensor device (100, 200, 300, 400, 500, 600, 700) is configured to detect an electrical measurement variable of the measuring structure (120, 220, 320, 420, 520, 620, 720) and determine the hydrogen concentration based on the detected electrical measurement variable.

2. The sensor device (100, 200, 300, 400, 500, 600, 700) according to claim 1, characterized in that The measuring structure (120, 220, 320, 420, 520, 620, 720) is substantially completely exposed.

3. The sensor device (200, 300, 400, 500) according to claim 1, characterized in that The measuring structure (220, 320, 420, 520) is arranged on the substrate (210, 310, 410, 510) by means of at least one distance element and / or by means of at least one dielectric layer (535, 536), the distance element being in particular configured as the contact conductor track (230, 330, 430, 530) and / or being configured by the material of the contact conductor track (230, 330, 430, 530).

4. The sensor device (100, 400, 600, 700) according to any one of the preceding claims, characterized in that The substrate (110, 410, 610, 710) has a recess (112, 412, 612, 712) below the measurement structure (120, 420, 620, 720) extending at least partially through the substrate.

5. The sensor device (300, 400, 500) according to any one of the preceding claims, characterized in that The measuring structure (320, 420, 520) is designed in an arcuate and / or stepped and / or meandering manner in a plane perpendicular to a main extension plane of the substrate (310, 410, 510) and / or in a plane parallel to a main extension plane of the substrate (310, 410, 510).

6. The sensor device (700) according to any one of the preceding claims, characterized in that The ratio of the height (722) to the width (724) of the measuring structure (720) is greater than 1:1, in particular greater than 2:1, particularly preferably greater than 4:

1.

7. The sensor device (700) according to claim 6, characterized in that A heating element (740) is arranged at least in regions below the measuring structure (720), the heating element being embedded in particular in at least one dielectric layer (735).

8. The sensor device (700) according to claim 6 or 7, characterized in that The sensor device (700) has a plurality of measuring structures (720) which are arranged adjacent to one another.

9. The sensor device (100, 200, 300, 400, 500, 600, 700) according to any one of the preceding claims, characterized in that The measuring structure (120, 220, 320, 420, 520, 620, 720) essentially comprises palladium.

10. The sensor device (100, 200, 300, 400, 500, 600, 700) according to any one of the preceding claims, characterized in that The measuring structure (120, 220, 320, 420, 520, 620, 720) has, at least in regions on its surface, a passivation layer which is preferably permeable only to hydrogen.

11. The sensor device (600) according to any one of the preceding claims, characterized in that The sensor device (600) has a cover element (640) having at least one cutout (642), wherein the measuring structure (620) is arranged between the cover element (640) and the substrate (610).

12. The sensor device (700) according to claim 11, characterized in that The at least one break (642) is closed by means of an element (643) which is preferably permeable only to hydrogen.

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