WO2018077615A1

WO2018077615A1 - Sensor element for detecting particles of a measuring gas in a measuring gas chamber

Info

Publication number: WO2018077615A1
Application number: PCT/EP2017/075907
Authority: WO
Inventors: Andreas Schulze; Enno Baars; Andy Tiefenbach; Karola Herweg
Original assignee: Robert Bosch Gmbh
Priority date: 2016-10-24
Filing date: 2017-10-11
Publication date: 2018-05-03
Also published as: KR20190071719A; DE102016220832A1; CN109891211B; CN109891211A

Abstract

The invention relates to a sensor element (110) for detecting a measuring gas in a measuring gas chamber. The sensor element (110) comprises a support (112), wherein a first electrode device (114) and a second electrode device (116) are mounted on the support (112). The first electrode device (114) and a second electrode device (116) respectively comprise several electrode fingers (118), each electrode finger (118) of the first electrode device (114) being connected to at least one electrode finger (118) of the second electrode device (116) by at least one terminating resistor (120).

Description

description

title

Sensor element for detecting particles of a measuring gas in one

Measuring gas chamber

State of the art

From the prior art, a plurality of sensor elements for detecting particles of a measuring gas in a measuring gas space is known. For example, the measuring gas may be an exhaust gas of an internal combustion engine. In particular, the particles may be soot or dust particles. The invention will be described below without limitation

Embodiments and applications, in particular with reference to sensor elements for the detection of soot particles described.

Two or more metallic electrodes may be mounted on an electrically insulating support. Which under the action of a

Voltage-accumulating particles, in particular the soot particles, form in a collecting phase of the sensor element electrically conductive bridges between the electrodes, which are designed, for example, as comb-like interdigital electrodes, and thus short-circuit them. In a regenerating phase, the electrodes are usually baked by means of an integrated heating element. As a rule, they value

Particle sensors the changed due to the particle accumulation electrical properties of an electrode structure. For example, a decreasing resistance or current at constant applied voltage can be measured.

Sensor elements operating on this principle are generally referred to as resistive sensors and exist in a variety of ways

Embodiments, such as from DE 103 19 664 AI, DE 10 2006 042 362 AI, DE 103 53 860 AI, DE 101 49 333 AI and WO 2003/006976 A2 known. The configured as soot sensors sensor elements are usually for Monitoring of diesel particulate filters used. In the exhaust tract of a

Internal combustion engine, the particle sensors of the type described are usually included in a protective tube, which allows, for example, the flow of the particle sensor with the exhaust gas at the same time.

Due to increasing environmental awareness and partly due to legal regulations, the soot emissions must be monitored while driving and the functionality of the monitoring must be ensured. This type of functionality monitoring is commonly referred to as on-board diagnostics. Devices and methods for the self-diagnosis of a particle sensor are described, for example, in DE 10 2009 028 239 A1, DE 10 2009 028 283 A1, DE 2007 046 096 A1, DE 10 2006 042 605 A1 and US Pat

2012/0119759 AI known.

Despite the advantages of the known from the prior art sensor elements for detecting particles that still contain potential for improvement. Thus, in particular the legally required self-monitoring of the soot sensor in terms of electrical functionality is difficult to implement. In particular, a continuous monitoring, preferably with a fixed predetermined minimum frequency, such as a monitoring with at least 2 Hz, presents a challenge. Furthermore, parasitic effects, such as the impedance of a harness to be measured, the

Self-diagnosis difficult. Deposits with unknown electrical properties, for example on electrode devices, can also be used

Overlays of the desired measurement effect lead. Furthermore, known methods and / or known devices may have the disadvantage that in the event of a fault, a total failure is always detected, even if the

Electrode device at a partial defect still partially, in particular, for example, still to 90%, is functional.

Disclosure of the invention

In the context of the present invention, therefore, a sensor element for detecting particles of a measuring gas in a measuring gas space

proposed. Under a sensor element is used in the present

Invention understood any device which is suitable to detect the particles qualitatively and / or quantitatively and which, for example, with the help a suitable drive unit and suitably designed electrodes can generate an electrical measurement signal corresponding to the detected particles, such as a voltage or a current. The detected particles may in particular be soot particles and / or dust particles. In this case, DC signals and / or AC signals can be used. Of

Furthermore, for example, a resistive component and / or a capacitive component can be used for signal evaluation from the impedance.

The sensor element can be set up in particular for use in a motor vehicle. In particular, the measuring gas may be an exhaust gas of the motor vehicle. Other gases and gas mixtures are possible in principle. In principle, the measurement gas space can be any, open or closed space in which the measurement gas is received and / or which is flowed through by the measurement gas. For example, the measuring gas space may be an exhaust gas tract of an internal combustion engine, for example an internal combustion engine.

The sensor element comprises a carrier, wherein a first electrode device and a second electrode device are applied to the carrier. The first electrode device and the second electrode device each have a plurality of electrode fingers, each electrode finger of the first electrode device being connected to at least one electrode finger of the second electrode device by at least one terminating resistor.

Under a carrier is understood in the context of the present invention, in principle, any substrate, which is suitable, the first

To carry electrode device and the second electrode means, and / or to which the first electrode means and the second electrode means can be applied. For the purposes of the present invention, electrode devices are understood in principle to be any electrical conductors which are suitable for current measurement and / or voltage measurement, and / or which can act on at least one element in contact with the electrode devices with a voltage and / or current. The term electrode finger is used in the context of the present

Invention understood basically any shaping of the electrode device whose dimension in one dimension, the dimension in at least clearly exceeds a different dimension, for example at least by a factor of 2, preferably by at least a factor of 3, more preferably by at least a factor of 5. In the context of the present invention, a plurality is understood to mean any number of at least two.

In the context of the present invention, a terminating resistance is basically understood as meaning any electrical resistance which electrically connects at least one electrode finger of the first electrode device to at least one electrode finger of the second electrode device such that particles deposited in the absence of deposited particles, in particular in the absence of deposited soot or dust particles Applying a voltage to the first and the second electrode means between the first electrode means and the second electrode means a measurable current flows. In particular, the measurable current when applying a voltage of 5 to 60 V during an operating temperature of the sensor element in a temperature interval of 50 ° C to 500 ° C assume a current value of 0.1 μΑ to 10 μΑ.

The at least one terminating resistor may comprise at least a portion of an electrode finger of the first electrode device and at least one

Touch section of an electrode finger of the second electrode device. In the context of the present invention, a section of an electrode finger is basically understood to mean any segment of an electrode finger. In particular, the at least one terminating resistor can also be a section or several sections or all sections of all

Touch electrode fingers of the first electrode means and a portion or multiple portions or all portions of all electrode fingers of the second electrode means. The at least one terminating resistor may be, for example, discrete

Component be applied to the carrier. The at least one

However, termination resistance may also be even closer below

described doping be configured within the carrier.

In a particularly preferred embodiment of the sensor element according to the invention, the at least one terminating resistor can be configured such that in the absence of deposited particles, in particular in the absence of deposited soot or dust particles, preferably in the Operating temperature of the sensor element, an electrode total resistance in a range of 1 Ω to 150 Ω, preferably in a range of 2 Ω to 75 Ω and more preferably in a range of 5 Ω to 50 Ω. The term "total electrode resistance" in the context of the present invention is the electrical resistance of the first

Electrode device understood by the second electrode means by the at least one terminating resistor and optionally formed by other components circuit. Due to the low resistance of the two electrode devices, the

Electrode total resistance usually essentially the

Terminator or, in the case of multiple terminators, a sum of terminators.

In the context of the present invention, the term "connected via a terminating resistor" basically means that each

Electrode fingers of the first electrode device with at least one

Electrode fingers of the second electrode means by means of a

Terminating resistor is in electrical contact. The carrier may comprise as carrier material at least one ceramic material. In particular, the support may comprise an oxidic ceramic, preferably aluminum oxide, in particular Al 2 O 3. However, other oxides, for example zirconium oxide, are possible. Furthermore, the carrier may comprise at least one electrically insulating material. The wearer can have a

Have carrier surface. In the context of the present invention, a carrier surface is understood basically to mean any layer which delimits the carrier from its surroundings, and to which the first and the second electrode device are applied. The carrier may comprise at least one doping region, wherein the

Doping region touches at least a portion of an electrode finger of the first electrode means and at least a portion of an electrode finger of the second electrode means. In particular, the doping region may also touch a portion or a plurality of portions or all portions of all the electrode fingers of the first electrode means and one or more portions or all portions of all the electrode fingers of the second electrode means. The term touching is used in the Under the present invention basically understood that two objects are in direct contact. In particular, the two objects can be in electrical contact. In the context of the present invention, a doping region is understood as meaning in principle any region of the carrier which has impurities introduced into the carrier material, in particular metal atoms, the metallic impurities replacing a part of the metal atoms contained in the carrier material. As a result, the doping region may comprise at least one doped carrier material, in particular an aluminum oxide doped with metal oxides. However, other oxides are possible, especially those which are also used as doping material.

The carrier can thus in the at least one doping region with a

Doping be doped, wherein the doping material with the metallic

Foreign atoms provided oxidic support material. In particular, a concentration of the doping material in the at least one

Dotierbereich a value of 1 mol% to 100 mol%, preferably from 10 mol% to 90 mol% and particularly preferably from 20 mol% to 80 mol%. In a more conspicuous embodiment, therefore, in the doping region, the

Carrier material must be completely replaced by the doping material.

The doping material may preferably comprise a metal oxide, wherein the

Doping material is preferably selected from the group consisting of iron oxide, in particular Fe 2 O 3; ZrO 2; Cr203; MgO; MnO; Snri203; Tb ₄ Ü7; Gd203;

Y2O3 and any mixture of these materials.

In a particularly preferred embodiment, the carrier Al 2 O 3 and the doping region 20 mol% to 100 mol% Fe ₂ 0 ₃ , preferably 40 to 80 mol% Fe ₂ 0 ₃ , especially since the so-prepared ceramic mixed oxide via a suitable electrical Leifähigkeit features.

In a further preferred embodiment, the oxides Snri203; Tb ₄ Ü7; Gd2Ü3 and / or Y2O3 suitable for doping. In this case, the doping from a combination of at least two oxides can prove to be advantageous, for example, the lowest possible temperature response of an electrical resistance of the doped carrier material within a selected To realize Temperturfensters. The concentrations of each

Doping materials may each have a value of 0 mol% to 100 mol% in the at least one doping region, for example, a

Material combination Sm ₂ 0 ₃ / Tb ₄ 0 ₇ / Gd ₂ 0 ₃ / Y ₂ 0 ₃ in the ratio 25% / 50% / 0% / 25% are used as particularly advantageous. Other conditions are possible.

A width of the doping region may be in a range from 10 μm to 2 mm, preferably from 25 μm to 500 μm, and particularly preferably from 50 μm to 250 μm. Furthermore, a length of the doping region may be in a range of

10 μηη to 2 mm, preferably from 25 μηη to 500 μηη and more preferably from 50 μηη to 250 μηη are. A thickness of the doping region can furthermore be in a range from 0.1 μm to 100 μm, preferably from 1 μm to 50 μm, and particularly preferably from 2 to 20 μm.

Below a width of the doping region is within the scope of the present

Invention basically the extension of the doping region in that

Room dimension understood, which is parallel to the support surface and perpendicular to the main extension direction of the electrode finger, which touches the doping region. In the context of the present invention, a length of the doping region is basically understood to mean the extent of the doping region in that spatial dimension which is parallel to the carrier surface and parallel to the main direction of extent of the electrode finger which the doping region contacts. In the context of the present invention, a thickness of the doping region is basically the

Extension of the doping region understood in that space dimension, which extends perpendicular to the support surface.

An electrical conductivity of the at least one doping region, in the absence of deposited particles in a temperature interval of 50 ° C to

500 ° C in a range of 1-10 ^"9 (Qcm) ^{" 1} to 10 (Qcm) ^"1 , preferably in a range of 1-10 ^{" 8} (Qcm) ^"1 to 1-10 ^{" 2} (Qcm) ^{" 1} and more preferably in a range of 1-10 ^"7 (Qcm) ^{" 1} to 1-10 ^"3 (Qcm) ^{" 1} .

The electrode fingers of the first and / or the second Elektrodeneinrichtu may have a meandering course. Under a meander-shaped course is in the context of the present invention, in principle, an arbitrary course of the electrode device on the

Understood carrier surface having at least one S-shape and / or at least one snake shape and / or at least one turn. Furthermore, the electrode fingers of the first electrode device and the

Electrode fingers of the second electrode device comb-like mesh.

The electrode fingers of the first electrode device may be spaced apart from one another, wherein the distance of the electrode fingers of the first

Electrode device may be constant within the sensor element or at least over a portion of the sensor element may vary. The

Electrode fingers of the second electrode device can likewise have a spacing from one another, wherein the distance of the electrode fingers of the second electrode device within the sensor element can be constant or at least vary over a part of the sensor element. The

Electrode fingers of the first electrode device may have a spacing from the electrode fingers of the second electrode device, wherein the distance within the sensor element may be constant or at least vary over a part of the sensor element.

The sensor element may have at least two terminating resistors. The terminating resistors can have different values. The

Termination resistors can also all have the same value. At different values, if necessary, an error assignment can be realized, which area is affected and from which a correction function in the control unit can be realized, which enables an area-dependent compensation of this error with higher accuracy in the signal evaluation.

The terminators can all be in one area of the

The cold region of the sensor element may in this case comprise in particular a side with connection contacts to a cable harness and typically by means of a sealing pack from the hot exhaust gas However, the terminating resistors may at least partially lie in a region of the sensor element, which is also referred to as "hotter The area of the sensor element can be referred to and which is acted upon by the particles of the measuring gas.This can be the actual measuring range of the electrodes, the printed electrode leads can be mounted in a transition region

Terminating resistors are at least partially in a control unit. The at least partial accommodation of the terminating resistors in the

Control unit allows a higher temperature stability in comparison to outside the control unit accommodated termination resistors.

In the case of a sensor element according to the invention with only a single terminating resistor, the terminating resistor can be accommodated in the control unit. This allows a higher compared to a mounted outside of the controller termination

Temperature stability. However, the one terminating resistor can also be located in a region of the sensor element which is not acted on by the particles of the measuring gas. Furthermore, the one terminating resistor can also be located in a region of the sensor element which is acted on by the particles of the measuring gas.

The sensor element can be configured in particular as a soot particle sensor. Furthermore, the sensor element can be accommodated in at least one protective tube.

In a further aspect of the present invention, a method for producing a sensor element for detecting particles of a measurement gas in a measurement gas space is proposed, which comprises the following steps, preferably in the order given. Also a different order is possible. Furthermore, one or more or all of the method steps can also be carried out repeatedly. Furthermore, two or more of the method steps may also be performed wholly or partially overlapping in time or simultaneously. The method may, in addition to the method steps mentioned, also comprise further method steps. The process steps are:

a) providing a carrier; b) applying a first electrode means and a second

Electrode device on the carrier, wherein the first

Electrode means and the second electrode means comprise a plurality of electrode fingers;

c) generating at least one terminator on the carrier or in the carrier, each electrode finger of the first

Electrode device is connected to at least one electrode finger of the second electrode device by at least one terminator.

The method can be used, in particular, for producing a sensor element according to the present invention, that is to say according to one of the above-mentioned

Embodiments or according to one of the embodiments described in more detail below are used. Accordingly, for definitions and optional embodiments, the description of the

Sensor element are referenced. However, other embodiments are possible in principle.

In step c), a thick-film technology for applying the

Terminating resistor can be used on the carrier or it can be a doping of the carrier to produce at least one doping region in the carrier. When using the thick-film technology to produce the terminating resistor, the terminating resistor can be considered discrete

Component on the support, in particular on the ceramic substrate to be printed.

The proposed device and method have numerous advantages over known devices and methods. Due to the inventive design of the electrode devices, in particular the electrode structure, it may be possible to use a

Self-diagnostic ability of a sensor element for detecting particles of a sample gas in a sample gas chamber over the prior art to improve. In particular, it may be possible to use the electrode fingers of the first electrode device and the electrode fingers of the second one

To monitor electrode device individually, in particular with a frequency of at least 2 Hz. In particular, it may be possible in the case of a defect of an electrode finger or fewer electrode fingers to this defect detect and continue to use the sensor element based on the remaining, intact electrode fingers.

Furthermore, it may be possible to improve the accuracy, in particular the

Measurement accuracy, using the inventive sensor element over the prior art, especially in the case of one or more defective electrode fingers to increase. In particular, it may be possible to carry out a compensation of the measurement signal in the case of a detection of a partial defect in accordance with the reduced sensitivity of the sensor element, as long as it does not fall below a minimum value.

Furthermore, it is possible to select the number of electrode fingers as high as possible. This may make it possible in the event of an error as high as possible

To achieve differentiation between a defective area and an intact area. In particular, it may be possible that with a high number of

Electrode fingers the defect of a single electrode finger or a few electrode fingers has little effect. In particular, it may be possible to compensate for the defect of one or fewer electrode fingers, especially with low loss of sensitivity.

Furthermore, the terminating resistors may be located in the region which is not exposed to the particles of the measuring gas, in particular in a cold region or colder region of the sensor element. Furthermore, it is also possible that the terminators are in the control unit, which can allow a high temperature stability.

Furthermore, it may be possible that when using the thick-film technology, especially when using a current thick-film technology, to implement the electrode devices to the terminators no further changes are required.

Brief description of the drawings

Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures. Show it:

Figures 1 to 3 different embodiments of a

Sensor element according to the invention, wherein the

Sensor element is shown in a plan view;

FIG. 4 shows a dependency of a

Total electrode resistance or a

Self-diagnostic current of a number of defective ones

Electrode fingers in a sensor element; and

Figures 5 to 6 different embodiments of a

inventive sensor element in one

Cross-sectional view.

Embodiments of the invention

In the figures 1 to 3 are different embodiments of a

Sensor element 110 according to the invention for detecting particles of a sample gas in a sample gas chamber in a plan view. FIG. 4 shows in the form of a diagram 130 a dependency of the

Total electrode resistance 128 and a dependence of

Self-diagnostic current 126 from a number of defective electrode fingers 132, wherein the diagram 130 refers to the embodiment shown in Figure 3 of a sensor element 110 according to the invention. FIGS. 5 and 6 show various embodiments of a sensor element 110 according to the invention for detecting particles of a measurement gas in a measurement gas space in a cross-sectional view. These figures will be explained together below.

The sensor element 110 can be set up in particular for use in a motor vehicle. In particular, the measuring gas may be an exhaust gas of the motor vehicle. The sensor element 110 can in particular comprise one or more further functional elements not shown in the figures, such as electrodes, electrode leads and contacts, multiple layers, heating elements, electrochemical cells or others

Elements as shown for example in the above-mentioned prior art. Furthermore, the sensor element 110 may for example be accommodated in a protective tube, also not shown. The sensor element 110 comprises a carrier 112, wherein a first electrode device 114 and a second electrode device 116 are applied to the carrier 112. The first electrode device 114 and the second

Electrode device 116 have a plurality of electrode fingers 118, wherein each electrode finger 118 of the first electrode device 114 is connected to at least one electrode finger 118 of the second electrode device 116 by at least one terminator 120.

The at least one terminating resistor 120 may, for example, be applied to the carrier 112 as a discrete component, as shown in FIG. However, the at least one terminating resistor 120 can also be designed as a doping region 122 described in greater detail below within the carrier 112, as shown in FIG.

The carrier 112 can be used as a carrier material in these preferred

Embodiments comprise at least one ceramic material.

In particular, the carrier 112 may comprise aluminum oxide, in particular Al 2 O 3. Furthermore, the carrier 112 may comprise at least one electrically insulating material.

The carrier 112 may include at least one doping region 122, wherein the doping region 122 comprises at least a portion of an electrode finger 118 of the first electrode device 114 and at least a portion of a

Electrode finger 118 of the second electrode means 116 contacts, as in

FIG. 6. In particular, the doping region 122 may also include a portion or multiple portions of all of the electrode fingers 118 of the first

Electrode device 114 and a portion or multiple portions of all electrode fingers 118 of the second electrode device 116 touch. The portion of the electron finger 118 of the first electrode device 114 and the portion of the electrode finger 118 of the second electrode device 116 contacting the doping region 122 may be in electrical contact with the doping region 122.

The carrier 112 may have in the at least one doping region 122 introduced into the ceramic material impurities, in particular metal atoms, wherein the metallic impurity atoms are part of the ceramic in the Replace the material of the carrier 112 contained metal atoms. As a result, the doping region 122 may comprise at least one doped ceramic material, in particular an aluminum oxide doped with metal oxides. Other oxides are possible. The carrier 112 may thus be in the at least one

Doping region 122 may be doped with a doping material, wherein the doping material refers to the provided with the metallic impurity oxidic ceramic. The doping material may preferably comprise a metal oxide, wherein the

Doping material is preferably selected from the group consisting of iron oxide, in particular Fe2Ü3; ZrCH; 0203; MgO; MnO, Sm 2 O 3, Tb ₄ 07, Gd 2 O 3, Y 2 O 3 and any mixture of these materials.

Furthermore, the doping material in the at least one doping region 122 may have a concentration of from 1 mol% to 100 mol%, preferably from 10 mol% to 90 mol% and particularly preferably from 20 mol% to 80 mol%.

In particular, the carrier 112 may comprise Al 2 O 3 and the doping region 122 may have 40 to 80 mol% Fe 2 O 3.

A width b of the doping region 122 may be in a range from 10 .mu.m to 2 mm, preferably from 25 .mu.m to 500 .mu.m, and particularly preferably from 50 .mu.m to 250 .mu.m. Furthermore, a length of the doping region may be in a range of

10 μηη to 2 mm, preferably from 25 μηη to 500 μηη and more preferably from 50 μηη to 250 μηη are. A thickness d of the doping region can furthermore be in a range from 0.1 μm to 100 μm, preferably from 1 μm to 50 μm, and particularly preferably from 2 to 20 μm. The width b and the thickness d of

Doping region are shown in FIG. An electrical conductivity of the at least one doping region, in the absence of deposited particles in a temperature interval of 50 ° C to 500 ° C in a range of 1-10 ^"9

(Qcm) ^"1 to 10 (Qcm) ^{" 1} , preferably in a range of 1-10 ^"8 (Qcm) ^{" 1} to 1-10 ^"2 (Qcm) ^{" 1,} and more preferably in a range of 1-10 ^{" 7} (Qcm) ^"1 to 1-10 ^{" 3} (Qcm) ^"1 .

The electrode fingers 118 of the first electrode device 114 and / or the electrode fingers 118 of the second electrode device 116 may have a meandering course 124. FIGS. 1 and 2 show two examples of a meander-shaped course 124. The electrode fingers 118 of the first electrode device 114 and the electrode fingers 118 of the second one

Electrode device 116 may have a plurality of other meandering ones Have gradients. Furthermore, the electrode fingers 118 of the first electrode device 114 and the electrode fingers 118 of the second

Electrode means 116 mesh like a comb, as shown in Figures 1-3, 5 and 6.

The sensor element 110 may have at least two terminating resistors 120, as shown in FIGS. 1-3, 5 and 6. The terminating resistors 120 may have different values. The terminating resistors 120 may, however, also all have the same value.

The electrode fingers 118 of the first electrode device 114 may have a distance a from one another, wherein the distance a of the electrode fingers 118 of the first electrode device 114 may be constant within the sensor element 110, as shown in FIG. 3, or at least vary over a part of the sensor element 110. The electrode fingers 118 of the second

Electrode device 116 may have a distance c from each other, wherein the distance c of the electrode fingers 118 of the second electrode device 116 may be constant within the sensor element 110, as shown in Figure 3, or at least over a portion of the sensor element 110 may vary. The electrode fingers 118 of the first electrode device 114 may have a

Distance e from the electrode fingers 118 of the second electrode means 116, wherein the distance e may be constant within the sensor element 110, as shown in Figure 3, or at least over a part of the

Sensor element 110 may vary.

The termination resistors 120 may all be in a region of the

Sensor element 110 are located, which is not acted upon by the particles of the sample gas. However, the terminating resistors 120 may at least partially lie in a region of the sensor element 110, which is acted on by the particles of the measuring gas. Furthermore, one or more of the existing terminating resistors 120 may be located in a control unit not shown in the figures.

In the context of the present invention, the term "total electrode resistance" refers to the electrical resistance of the first electrode device, through the second electrode device, through the at least one electrode

Terminating resistor and optionally formed by other components Circuit understood. The total electrode resistance may be in a range of 1 Ω to 150 Ω, preferably in a range of 2 Ω to 75 Ω, and more preferably in a range of 5 Ω to 50 Ω. Due to the low resistance of the two electrode devices, the total electrode resistance generally comprises essentially

Terminating resistor or, in the event that multiple terminators are present, a sum of the terminating resistors, which is hereinafter referred to as Rges. In particular, a total resistance R _{tot of} the existing can be

Terminating resistors 120 for the embodiment shown in Figure 3 of a sensor element 110 according to the invention with a total of n electrode fingers 118 calculate as follows:

wherein the first electrode means 114 has a number of n / 2 electrode fingers 118, and wherein the second electrode means 116 also has a number of n / 2 electrode fingers 118, and wherein each electrode finger 118 of the first electrode means 114 has at least one electrode finger

118 of the second electrode means by at least one

Terminating resistor R, (120) is connected. The terminating resistors R, 120 may all have the same value Ro. For this case, the following calculation of the total resistance R _ges results

Rges / RO = ^l f _n (3) Furthermore, the total resistance R _ges for the illustrated in Figure 3 can be

Embodiment of a sensor element 110 according to the invention with a number of m defective electrode fingers 118 for a total of n electrode fingers 118 calculate as follows,

where 1) 0, the first electrode device 114 has a number of n / 2 electrode fingers 118 which may be intact or at least partially defective, and wherein the second electrode device 116 also has a number of n / 2 electrode fingers 118 which are intact or at least partially defective and each electrode finger 118 of the first

Electrode device 114 is connected to at least one electrode finger 118 of the second electrode device by at least one terminating resistor R, 120: The terminating resistors R, 120 may all have the same value Ro. For this case, the following calculation of the

Total resistance R _ses :

The sensor element 110 can be configured in particular as a soot particle sensor. Furthermore, the sensor element 110 can be accommodated in at least one protective tube, not shown in the figures.

For self-diagnosis, at least temporarily a measuring voltage can be applied between the first electrode device 114 and the second electrode device 116 and a self-diagnosis current 126 and / or a

Total electrode resistance 128 can be measured. Of the

Self-diagnostic current 126 flows through the first electrode device 114, the second electrode device 116 and the at least one

Termination resistor 120. The self-diagnostic current 126 may be a measure of the functionality of the sensor element 110 and / or the quality of the

Be sensor element 110.

FIG. 4 shows, by way of example, a diagram 130, in which the self-diagnosis current 126 is determined as a function of the number of defective electrode fingers 132, as well as the number of defective electrode fingers 132

Total electrode resistance 128 as a function of the number of defective ones

Electrode finger 132 is shown. The diagram 130 in FIG. 4 relates to the embodiment of a sensor element 110 shown in FIG. 3. A current 134 is plotted over the number of defective electrode fingers 132, as well as a resistor 136 over the number of defective electrode fingers 132.

Claims

claims

Sensor element (110) for detecting particles of a measuring gas in a measuring gas space, wherein the sensor element (110) comprises a carrier (112), wherein on the carrier (112) a first electrode means (114) and a second electrode means (116) are applied, the first one

Electrode means (114) and the second electrode means (116) each having a plurality of electrode fingers (118), wherein each electrode finger (118) of the first electrode means (114) with at least one electrode finger (118) of the second electrode means (116) by at least one terminator (120) is connected.

Sensor element (110) according to the preceding claim, wherein the carrier (112) comprises at least one doping region (122), wherein the doping region (122) at least a portion of an electrode finger (118) of the first electrode means (114) and at least a portion of a

Touched electrode finger (118) of the second electrode means (116).

Sensor element (110) according to the preceding claim, wherein the carrier (112) in the at least one doping region (122) is doped with at least one doping material, wherein the doping material is selected from the group consisting of iron oxide, ZrCh, Cr 2 O 3, MgO, MnO, Sm203, Tb ₄ 07, Gd ₂ 0 ₃ and Y ₂ 0 ₃ .

Sensor element (110) according to the preceding claim, wherein the doping material in the at least one doping region (122) in a

Concentration of 1 mol% to 100 mol% is present.

Sensor element (110) according to one of the three preceding claims, wherein the at least one doping region (122) has a width of 10 μm to 2 mm and / or a length of 10 μm to 2 mm and / or a thickness of 0.1 μm to 100 has μηη.

Sensor element (110) according to one of the four preceding claims, wherein the at least one doping region (122) in a temperature interval of 50 ° C to 500 ° C an electrical conductivity of 1-10 " ⁹ (Qcm) - ¹ to 10 (Qcm) ^{" 1} has.

7. Sensor element (110) according to one of the preceding claims, wherein the sensor element (110) has at least two terminating resistors (120). 8. Sensor element (110) according to the preceding claim, wherein the

at least two terminating resistors (120) each have different values.

Sensor element (110) according to claim 6, wherein the at least

Terminators (120) have the same value.

10. Sensor element (110) according to one of the preceding claims, wherein the terminating resistor (120) is introduced into a control unit.

11. Sensor element (110) according to any one of the preceding claims, wherein an electrode total resistance, which at least a sum of a resistance of the first electrode means (1 14), a resistance of the second electrode means (1 16) and a total resistance R _{ges of} the at least one terminating resistor (120 ) assumes a value of 1 Ω to 150 Ω.

12. A method for producing a sensor element (110) for detecting particles of a measurement gas in a sample gas space, the method comprising the following steps:

a) providing a carrier (112);

b) applying a first electrode means (114) and a second electrode means (116) to the carrier (112), the first electrode means (114) and the second electrode means (116) having a plurality of electrode fingers (118);

c) generating at least one termination resistor (120) on the carrier (112) or in the carrier (112), wherein each electrode finger (118) of the first electrode device (114) with at least one electrode finger (118) of the second electrode device (116) at least one terminator (120) is connected.