KR20210146927A - a gas sensor for detecting at least one characteristic of a gas - Google Patents

Abstract

The invention relates to a gas sensor (10) for detecting at least one characteristic of a gas, in particular for detecting particles, in particular soot particles, in a measuring gas, in particular in the exhaust gas of an internal combustion engine. The sensor 10 comprises a sensor element 12 , said sensor element 12 comprising at least a substrate 14 , an electrically insulating element 24 , a first electrode 16 and a second electrode 18 . . The first electrode 16 is connected to the first supply line 20 , the second electrode 18 is connected to the second supply line 22 , the first electrode 16 , the second electrode 18 , The first supply line 20 and the second supply line 22 are arranged on the substrate 14 , the electrically insulating element 24 is also arranged on the substrate 14 , the first electrode 16 and the second The electrode 18 is designed to carry out current and/or voltage measurements, the sensor element 12 being the first supply line 20 and/or the second supply when viewed in the longitudinal direction 27 of the sensor element 12 . at least one channel 28 in the region of the line 20 , said channel 28 being formed at least partially in the electrically insulating element 24 .

Description

a gas sensor for detecting at least one characteristic of a gas

The present invention relates to a gas sensor for detecting at least one characteristic of a gas.

A number of sensors and methods are known from the prior art for detecting at least one characteristic of a measuring gas in a measuring gas space. Said properties may in principle be all physical and/or chemical properties of the gas to be measured, and one or more properties may be detected. Such sensors enable qualitative and/or quantitative detection of the gas component ratio of the measurement gas, for example detection of the oxygen ratio in the measurement gas. The oxygen ratio can be detected, for example, in the form of partial pressures and/or in the form of percentages. However, alternatively or additionally, other properties of the measuring gas, for example temperature, can also be detected.

For example, such sensor elements are described, for example, in Konrad Reif (Ed.): Sensoren im Kraftfahrzeug (Vehicle Sensors), 1st Edition 2010, pp. 160-165 can be designed as so-called lambda probes. With broadband lambda probes, in particular planar broadband lambda probes, for example, the oxygen concentration in the exhaust gas over a wide range can be determined and the air-fuel ratio in the combustion chamber can be deduced accordingly. The air ratio I represents this air-fuel ratio.

Numerous methods and devices are known from the prior art for the detection of particles, for example soot or dust particles.

The invention is described hereinafter in particular in relation to a sensor for detecting particles, in particular soot particles, in an exhaust gas stream of an internal combustion engine, but other embodiments and applications are not limited thereto. It is expressly emphasized that the described invention can also be applied to other types of sensors, such as, for example, lambda probes.

It is known in practice to measure the concentration of particles, such as soot or dust particles, in exhaust gases by means of two electrodes arranged on a ceramic. This can be done, for example, by measuring the electrical resistance of the material separating the two electrodes. More precisely, when a voltage is applied to the electrodes, the current flowing between the electrodes is measured. Soot particles are deposited between the electrodes due to electrostatic forces, and over time form electrically conductive bridges between the electrodes. The more such bridges, the more the measured current increases. Therefore, the short circuit of the electrode increases. The sensor element is heated to at least 700 °C by means of an integrated heating element and is periodically regenerated to burn out soot deposits.

Such sensors are used, for example, in exhaust systems of internal combustion engines, such as diesel-type internal combustion engines. These sensors are usually downstream of a drain valve or soot particle filter.

Despite the numerous advantages of particle detection devices known from the prior art, these devices still have room for improvement. Providing a porous layer on both sides of the supply line to the electrode improves the ability to drive away stored moisture and greatly reduces the pressure build-up inside the sensor element due to evaporation of the stored moisture during heating, but the supply lines, and for example The rigidity of other electrical components of the sensor element, such as the insulation resistance between the supply lines, may decrease, resulting in damage or malfunction of the components.

Therefore, at least one property of the gas which at least greatly avoids the disadvantages of the known sensors and improves the sensor robustness against moisture induced errors while increasing or maintaining the robustness of the electrical component, in particular in relation to rapid temperature gradients and porous soot A gas sensor for detecting, in particular a sensor for detecting particles, in particular soot particles, is proposed.

A gas sensor according to the invention for detecting at least one characteristic of a gas, in particular a sensor for detecting particles, in particular soot particles, in a measuring gas, in particular an exhaust gas of an internal combustion engine, comprises a sensor element. The sensor element has at least one substrate, an electrically insulating element, a first electrode and a second electrode. The first electrode is connected to the first supply line and the second electrode is connected to the second supply line. The first electrode, the second electrode, the first supply line and the second supply line are disposed on the substrate. An electrically insulating element is disposed on the substrate. The first and second electrodes are designed to perform current and/or voltage measurements. The sensor element has at least one channel in the region of the first supply line and/or the second supply line when viewed in the longitudinal direction of the sensor element, said channel being at least partially formed in or perpendicular to the electrically insulating element.

The addition of a porous insulating layer to the at least one channel provides a moisture entry and exit path that does not affect the electrical function of the sensor element. This may increase the robustness of the sensor element with respect to chipping. In the case of soot of pores in the porous insulating layer blocking the application channel of the stored moisture, the application channel provides a parallel path for drying. These channels do not have large storage volumes for additional moisture since they can be introduced with suitable dimensions only at the respective critical points in the construction of the sensor element. In addition, there is no need for major changes in the layer structure of the sensor element. The mechanical stability of the sensor element is therefore much less affected than if a completely porous layer was introduced. At the same time, the electrical properties remain unchanged.

In one refinement, the substrate is a ceramic substrate and the electrically insulating element is arranged on the substrate in such a way that the first electrode and the first supply line and/or the second electrode and the second supply line are electrically insulated with respect to the substrate. . This prevents short circuits between the electrodes and the supply lines to each other and/or to the substrate. For example, the first electrode, the second electrode, the first supply line and the second supply line are at least partially embedded in the electrically insulating element. For example, only the electrodes have access to the ambient measurement gas.

In one refinement, the channel is open in the substrate. This may cause moisture to migrate away from the substrate.

In one refinement, the electrically insulating element consists of a plurality of layers, and a channel is formed in at least one of said layers. In this way, channels can be designed as intended in the layers as needed.

In one refinement, the layers differ in their porosity. In this way, channels can be designed as intended in the layers as needed. For example, channels are formed only in layers with low porosity so that more moisture can be carried there.

In one refinement, the channel completely penetrates the electrically insulating element. In this way, the amount of moisture to be transported can be increased. In this way also intended connections between different insulating layers can be formed.

In one refinement, the sensor element has a test pin disposed on a substrate, the channel being open at the test pin. Thus, the test pins are reliably protected from damage due to moisture.

In one refinement, the channel is opened at the front end of the test pin. Thus, channels are provided especially at critical or sensitive points to provide reliable protection of the test pin tip.

In one refinement, the channel overlaps the first supply line and/or the second supply line. Accordingly, moisture can be transported particularly well away from the supply lines.

In one refinement, the channel has a circular, oval, triangular, rectangular, polygonal cross-section or a polygonal cross-section with rounded corners. A channel may have a constant or variable cross-section along its length.

In one refinement, the channel is filled with a porous material. Providing some kind of support structure increases stability.

Particles in the context of the present invention are to be understood in particular as electrically conductive particles, for example soot or dust particles.

In the context of the present invention, an electrode is to be understood as a component suitable for measuring current and/or voltage. The designation of the first and second electrodes is only used to conceptually distinguish the electrodes in the context of the present invention and is not intended to indicate a specific order or weight of these parts.

In the context of the present invention, the electrode can be designed as an interdigital electrode. In the context of the present invention, interdigital electrodes are to be understood as meaning electrodes arranged in an interdigitated manner, in particular in a comb-shaped interdigitated manner.

In the context of the present invention, a measurement of current and/or voltage is to be understood as a measurement of current and/or voltage. Measurements are made between two electrodes or one electrode and a reference potential. For example, voltage control or voltage regulation measurements and/or current control and/or current regulation measurements may be performed. A specific voltage may be applied to the electrodes to measure the current flow between the electrodes or the electrode and the reference, or a constant current may be applied to the electrodes to measure the voltage between the electrodes or the electrode and the reference. The current and/or voltage measurement may in particular be a resistance measurement, and the resistance of a structure formed by the electrode and the substrate may be measured. For example, voltage control or voltage regulation measurements and/or current control and/or current regulation measurements may be performed. The application of current and/or voltage may take place in the form of a continuous signal and/or in the form of a pulsed signal. For example, a direct current voltage and/or direct current may be applied to detect a current response or a voltage response. Alternatively, a pulsed voltage and/or a pulsed current or alternating current may be applied and the current response or voltage response detected. Instead of the instantaneous current flowing through the electrode, the resistance of the electrode or its reciprocal (= conductivity) may be used as the measurement variable. It may also be desirable to integrate the amount of charge from the instantaneous current flow. It is also possible to measure a current such as a discharge current at a counter electrode or electrical ground by applying a high voltage to the electrode.

In the context of the present invention, a substrate is intended to mean an object having at least one flat surface and having a plate-like, cuboidal, cuboidal or other geometric design made of a ceramic material, a metallic material, a semiconductor material or a combination thereof. should be understood

The expression "in the region of the first and second supply lines" in the context of the present invention generally means the area where the supply lines overlap when viewed in a direction perpendicular to the longitudinal direction of the sensor element in which they extend. should be understood

In the context of the present invention, a test pin is to be understood as an electrical conductor track provided for electrical diagnostic purposes.

Further optional details and features of the invention emerge from the following description of a preferred embodiment schematically illustrated in the drawings.

1 is a plan view of a sensor for detecting particles according to a first embodiment of the present invention.
Figures 2a to 2c are cross-sectional views taken along line AA of Figure 1 of possible embodiments of the first embodiment;
3 is a plan view of a sensor for detecting particles according to a second embodiment of the present invention.
4A to 4C are cross-sectional views taken along line AA of FIG. 3 of possible embodiments of the second embodiment.
5 is a plan view of a sensor for detecting particles according to a third embodiment of the present invention.
6 is a cross-sectional view taken along line AA of FIG. 5 .
7 is a plan view of a sensor for detecting particles according to a fourth embodiment of the present invention.
8A and 8B are cross-sectional views taken along line AA of FIG. 7 of possible embodiments of the fourth embodiment.
9 is a cross-sectional view of a particle detection sensor according to a fifth embodiment of the present invention.
10 is a cross-sectional view of a sensor for detecting particles according to a sixth embodiment of the present invention.
11 is a plan view of a particle detection sensor according to a seventh embodiment of the present invention.
12 is a plan view of a particle detection sensor according to an eighth embodiment of the present invention.
13 is a cross-sectional view taken along line AA of FIG. 12 .

1 is a plan view of a sensor 10 for detecting particles of a measurement gas according to an embodiment of the present invention. The sensor 10 is designed in particular to detect soot particles in a gas stream of an internal combustion engine, for example an exhaust gas stream, and for installation in the exhaust system of a motor vehicle. For example, the sensor 10 may be designed as a soot sensor and disposed downstream or upstream of a soot particle filter of an automobile having a diesel internal combustion engine. In the illustrated embodiment, the measurement gas is an exhaust gas of an internal combustion engine. In the illustrated embodiment, the sensor 10 is designed as a resistive particle sensor.

The sensor 10 comprises a sensor element 12 . The sensor element 12 includes a substrate 14 . The substrate 14 may be an electrically insulating element. The substrate 14 is, for example, a silicon wafer. Alternatively, the substrate 14 is made of a ceramic material, such as for example a solid electrolyte, for example doped ZrO ₂ or an insulator, for example Al ₂ O _{3 .} Substrate 14 is substantially rectangular in shape. The sensor element 10 further comprises a first electrode 16 , a second electrode 18 , a first supply line 20 and a second supply line 22 . The first electrode 16 and the second electrode 18 are designed as interdigital electrodes. The first electrode 16 is connected to the first supply line 20 . The second electrode 18 is connected to the second supply line 22 . The first supply line 20 and the second supply line 22 form a connecting contact designed for electrical contacting of the first electrode 16 and the second electrode 18 . The first electrode 16 and the second electrode 18 are designed to perform current and/or voltage measurements.

The sensor element 12 also has an electrically insulating element 24 . The first electrode 16 , the second electrode 18 , the first supply line 20 and the second supply line 22 are arranged on the electrically insulating element 24 . The electrically insulating element 24 is disposed on the substrate 14 , for example on the upper surface 26 of the substrate 14 . In addition, the sensor element 12 has at least one channel 28 in the region of the first supply line 20 and the second supply line 22 when viewed in the longitudinal direction 27 of the sensor element 12 , The channel 28 is formed at least partially in the electrically insulating element 24 . The channel 28 is located midway between the first supply line 20 and the second supply line 22 . In the first embodiment, the channel 28 has a circular cross-section. The sensor element 12 also has a test pin 30 disposed on the substrate 14 .

Figures 2a to 2c are cross-sectional views taken along line A-A in Figure 1 of possible embodiments of the first embodiment; As can be seen in the embodiment of FIG. 2A , the electrically insulating element 24 has a first electrode 16 , a second electrode 18 , a first supply line 20 and a second supply line 22 connected to a substrate. It is arranged on the substrate 14 or its upper surface 26 in such a way that it is electrically insulated with respect to 14 . The first supply line 20 and the second supply line 22 are sandwiched by an electrically insulating element 24 , while the first electrode 16 and the second electrode 18 connect the substrate 14 to each other. Since only the side facing is covered by the electrically insulating element 24 , the side of the electrodes 16 , 18 , remote from the substrate, is exposed and can come into contact with the measuring gas. The electrically insulating element 24 consists of a number of layers 34 , 36 . A channel 28 is formed in at least one of the layers 34 , 36 . The layers 34 and 36 may differ in their porosity. For example, a layer 34 with low porosity and a layer 36 with high porosity are provided. In the embodiment shown, the sides of the electrodes 16 , 28 and the supply lines 20 , 22 , facing the substrate 14 , are disposed in a layer 34 with low porosity.

As can be seen in the embodiment of FIG. 2A , the channel 28 completely penetrates the electrically insulating element 24 . Channel 28 is open in substrate 14 . More precisely, channel 28 is opened at test pin 30 . More precisely, the channel 28 opens at the front end 32 of the test pin 30 . Channel 28 extends in a direction perpendicular to top surface 26 of substrate 14 . In the first embodiment, the channel 28 has a circular cross-section. The cross-section of the channel 28 is constant along the length of the channel 28 . Channel 28 can be implemented similarly to a flat porous insulating layer using an insulating paste mixed with a pore former during fabrication of sensor element 12 . Printing may be performed, for example, as an inlay of a dense insulating layer 36 in which the corresponding recesses are maintained.

With regard to the embodiment of Fig. 2B, only the differences from the embodiment of Fig. 2A are described below, and identical or similar parts are denoted by the same reference numerals. In the embodiment of FIG. 2B , the channel 28 does not completely penetrate the electrically insulating element 14 . Channel 28 opens in substrate 14 and terminates at the level of first supply line 20 or second supply line 22 .

With respect to the embodiment of Fig. 2C, only the differences from the embodiment of Fig. 2A are described below, and identical or similar parts are denoted by the same reference numerals. In the embodiment of FIG. 2C , the channel 28 does not completely penetrate the electrically insulating element 14 . The channel 28 extends from the outer surface 38 of the insulating element 24 into the insulating element and terminates at the level of the first supply line 20 or the second supply line 22 .

3 is a plan view of the sensor 10 for detecting particles according to the second embodiment of the present invention. Hereinafter, only the differences from the first embodiment are described and the same or similar parts are denoted by the same reference numerals. In the sensor 10 of the second embodiment, the channel 28 is open at the test pin 30 and at its front end 32 . In the second embodiment, the channel 28 has an elliptical cross-sectional shape. The major axis of the elliptical shape is oriented parallel to the longitudinal direction of the sensor element 12 .

Figures 4a to 4c are cross-sectional views taken along line A-A in Figure 3 of possible embodiments of the second embodiment; As can be seen in the embodiment of FIG. 4A , the channel 28 completely penetrates the electrically insulating element 14 . Channel 28 is open in substrate 14 . More precisely, channel 28 is opened at test pin 30 . More precisely, the channel 28 opens at the front end 32 of the test pin 30 and in the region adjacent to the test pin 30 . Channel 28 extends in a direction perpendicular to top surface 26 of substrate 14 .

With respect to the embodiment of Fig. 4B, only the differences from the embodiment of Fig. 4A are described below, and identical or similar parts are denoted by the same reference numerals. In the embodiment of FIG. 4B , the channel 28 does not completely penetrate the electrically insulating element 14 . Channel 28 opens in substrate 14 and terminates at the level of first supply line 20 or second supply line 22 .

With respect to the embodiment of Fig. 4C, only the differences from the embodiment of Fig. 4A are described below, and identical or similar parts are denoted by the same reference numerals. In the embodiment of FIG. 4C , the channel 28 does not completely penetrate the electrically insulating element 14 . The channel 28 extends from the outer surface 38 of the insulating element 24 into the insulating element and terminates at the level of the first supply line 20 or the second supply line 22 .

5 is a plan view of the sensor 10 for detecting particles according to the third embodiment of the present invention. Hereinafter, only the differences from the first embodiment are described and the same or similar parts are denoted by the same reference numerals. In the sensor 10 of the third embodiment, the sensor element 12 has a plurality of channels 28 . More precisely, the sensor element 12 has for example four channels 28 . In the illustrated embodiment, two channels 28 are open at the test pin 30 , and one channel 28 of them is open at the front end 32 of the test pin 30 . The other channels 28 overlap the first supply line 20 and the second supply line 22 respectively in plan view. The channels 28 each have a circular cross-sectional shape. The cross-sectional areas of the channels 28 may be the same size, or may be different sizes, as shown in FIG. 5 . In the embodiment shown in FIG. 5 , the channels 28 open at the test pin 30 have a larger cross-sectional area than the channels 28 overlapping the supply lines 20 , 22 when viewed in plan view.

6 is a cross-sectional view taken along line A-A of FIG. 5 . As can be seen in FIG. 6 , the channels 28 are not necessarily designed to be the same length, but may optionally have the same length. 6 , at least one of the channels 28 completely penetrates the electrically insulating element 14 and one of the channels 28 does not fully penetrate the electrically insulating element 14 . The last mentioned channel 28 opens at the front end 32 of the test pin 30 in the substrate 14 and ends at the level of the first supply line 20 or the second supply line 22 .

7 is a plan view of a particle detection sensor 10 according to a fourth embodiment of the present invention. Hereinafter, only differences from the first embodiment are described, and identical or similar parts are denoted by the same reference numerals. In the sensor 10 of the fourth embodiment, the sensor element 12 has a plurality of channels 28 . More precisely, the sensor element 12 has, for example, five channels 28 . In the illustrated embodiment, one of the channels 28 is open at a location spaced from the front end 32 at the test pin 30 .

8a and 8b show a cross-sectional view taken along line A-A of FIG. 7 , in which only one of the channels 28 is shown. In the embodiment shown in FIG. 8A , each channel 28 extends from the first supply line 20 or the second supply line 22 into the interior of the electrically insulating element 24 and is at the height of the test pin 30 . , more precisely at the height of its front end 32 .

In the embodiment shown in FIG. 8B , each channel 28 is electrically connected from the outer surface 38 of the electrically insulating element 24 to its interior and from the first supply line 20 or the second supply line 22 . It extends into the interior of the insulating element 24 and terminates at the level of the first supply line 20 or the second supply line 22 .

9 is a cross-sectional view of a particle detection sensor 10 according to a fifth embodiment of the present invention. Hereinafter, only differences from the first embodiment are described, and identical or similar parts are denoted by the same reference numerals. In the sensor 10 , a heating element or temperature measuring element 42 for heating the sensor element 12 is provided on the lower surface 40 of the substrate 14 opposite the electrodes 16 , 18 . A heating element or temperature measuring element 42 is embedded within an electrically insulating element 24 consisting of a plurality of layers 34 , 36 . The layers 34 and 36 differ in their porosity. As in the first embodiment, the channel 28 completely penetrates the electrically insulating element 24 at the top surface 26 of the substrate 14 . In addition, the channel 28 passes through the heating element or temperature measuring element 42 midway at the lower surface 40 of the substrate 14 to completely penetrate the electrically insulating element 24 .

10 is a cross-sectional view of a particle detection sensor 10 according to a sixth embodiment of the present invention. Hereinafter, only differences from the first embodiment are described, and identical or similar parts are denoted by the same reference numerals. In the sensor 10 of the sixth embodiment, a heating element or temperature measuring element 42 for heating the sensor element 12 is provided on the lower surface 40 of the substrate 14 opposite the electrodes 16 , 18 . provided A heating element or temperature measuring element 42 is embedded within an electrically insulating element 24 consisting of a plurality of layers 34 , 36 . The layers 34 and 36 differ in their porosity. Unlike the first embodiment, no channels 28 are formed in the electrically insulating element 24 on the upper surface 26 of the substrate 14 . On the other hand, on the lower surface 40 of the substrate 14 , a channel 28 extends from the outer surface 38 of the electrically insulating element 24 into it and ends at the height of the heating element 42 . Another channel 28 having a position offset in the direction of the front end of the sensor element 12 in the longitudinal direction 27 is on the lower surface 40 of the substrate 14 from the lower surface 40 of the substrate 14 . It extends inside the electrically insulating element 24 and ends at the height of the heating element or temperature measuring element 42 .

11 is a plan view of the sensor 10 for detecting particles according to the seventh embodiment of the present invention. Hereinafter, only differences from the first embodiment are described, and identical or similar parts are denoted by the same reference numerals. In the sensor 10 of the seventh embodiment, the sensor element 12 has a plurality of channels 28 . More precisely, the sensor element 12 has for example three channels 28 . In the illustrated embodiment, two channels 28 are formed laterally next to the test pin 30 , and one channel 28 is formed at a distance from the front end 32 of the test pin 30 . The additional channels 28 overlap the first supply line 20 and the second supply line 22 respectively in plan view. The channels 28 each have a circular or slightly elliptical cross-sectional shape. The cross-sectional areas of the channels 28 may be the same size or different sizes. The channels 28 may completely penetrate the electrically insulating element 24 , or alternatively one or more channels 28 may extend partially in the electrically insulating element 24 in the manner described above.

12 is a plan view of a particle detection sensor 10 according to an eighth embodiment of the present invention. 13 shows a cross-sectional view of FIG. 12 . Hereinafter, only differences from the first embodiment are described, and identical or similar parts are denoted by the same reference numerals. In the sensor 10 of the eighth embodiment, the sensor element 12 has a plurality of channels 28 . More precisely, the sensor element 12 has for example three channels 28 . In the illustrated embodiment, two channels 28 overlap either the first supply line 20 or the second supply line 22 , and one channel 28 is the front end 32 of the test pin 30 . formed at a certain distance from The additional channels 28 overlap the first supply line 20 and the second supply line 22 respectively in plan view. The channels 28 each have a circular or slightly elliptical cross-sectional shape. The cross-sectional areas of the channels 28 may be the same size or different sizes. The channels 28 may completely penetrate the electrically insulating element 24 , or alternatively one or more channels 28 may extend partially in the electrically insulating element 24 in the manner described above. As shown for example in FIG. 13 , a channel 28 spaced from the front end 32 of the test pin 30 may completely penetrate the electrically insulating element 24 , while two other channels 28 . ) extends from the outer surface 38 into the interior of the electrically insulating element 24 and terminates at the level of the first supply line 20 or the second supply line 22 .

All the described embodiments can be modified as follows. Channel 28 may be filled with a porous material. Channel 28 may have a triangular, rectangular, polygonal cross-section or a polygonal cross-section with rounded corners. Channel 28 may have a variable cross-section along its length. In other words, the cross-sectional area of the channel 28 may vary along its length.

10: gas sensor
12: sensor element
14: substrate
16: first electrode
18: second electrode
20: first supply line
22: second supply line
24: electrical insulation element
27: longitudinal direction
28: Channel
30: test pin
32: front end
34, 36: floor

Claims (12)

A gas sensor (10) for detecting at least one characteristic of a gas, in particular for detecting particles, in particular soot particles, in a measuring gas, in particular an exhaust gas of an internal combustion engine, said sensor (10) comprising: 12), wherein the sensor element (12) comprises at least a substrate (14), an electrically insulating element (24), a first electrode (16) and a second electrode (18), wherein the first electrode (16) is connected to a first supply line 20 , said second electrode 18 is connected to a second supply line 22 , said first electrode 16 , said second electrode 18 , said first The supply line 20 and the second supply line 22 are arranged on a substrate 14 , the electrically insulating element 24 is also arranged on the substrate 14 , the first electrode 16 and The second electrode 18 is designed to carry out current and/or voltage measurements, the sensor element 12 being the first supply line 20 when viewed in the longitudinal direction 27 of the sensor element 12 . and/or at least one channel (28) in the region of the second supply line (20), the channel (28) being formed at least partially in the electrically insulating element (24). 2. The electrode according to claim 1, characterized in that the substrate (14) is a ceramic substrate (14), and the electrically insulating element (24) comprises the first electrode (16) and the first supply line (20) and/or the second electrode. (16) and the second supply line (22) are disposed on the substrate (14) such that it is electrically insulated with respect to the substrate (14). 3. The gas sensor (10) of claim 2, wherein the channel (28) is open in the substrate (14). 4. The electrically insulating element (24) according to any one of the preceding claims, wherein said electrically insulating element (24) consists of a plurality of layers (34, 36), said channel (28) comprising at least one of said layers (34, 36). Formed in, the gas sensor (10). 5. Gas sensor (10) according to claim 4, wherein the layers (34, 36) have different porosity. 6. Gas sensor (10) according to any one of the preceding claims, wherein the channel (28) penetrates completely through the electrically insulating element (24). 7. The sensor element (12) according to any one of the preceding claims, wherein the sensor element (12) further comprises a test pin (30) disposed on the substrate (14), wherein the channel (28) comprises the test pin ( 30), the gas sensor (10). The gas sensor (10) of claim 7, wherein the channel (28) opens at the front end (32) of the test pin (30). The gas sensor (10) according to any one of the preceding claims, wherein the channel (28) overlaps the first supply line (20) and/or the second supply line (22). The gas sensor (10) according to any one of the preceding claims, wherein the channel (28) has a circular, elliptical, triangular, square, polygonal cross-section or a polygonal cross-section with rounded corners. 11. Gas sensor (10) according to any one of the preceding claims, wherein the channel (28) has a constant or variable cross-section along its length. 12. Gas sensor (10) according to any one of the preceding claims, wherein the channel (28) is filled with a porous material.

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