DE102016220832A1 - Sensor element for detecting particles of a measuring gas in a measuring gas chamber - Google Patents

Abstract

A sensor element (110) for detecting a measurement gas in a measurement gas space is proposed. 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) each have a plurality of electrode fingers (118), 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.

Description

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 limiting further embodiments and applications, in particular with reference to sensor elements for the detection of soot particles.

Two or more metallic electrodes may be mounted on an electrically insulating support. The accumulating under the action of a voltage particles, in particular the soot particles form in a collecting phase of the sensor element electrically conductive bridges between, for example, as comb-like interdigitated interdigital electrodes electrodes and close this short. In a regenerating phase, the electrodes are usually baked by means of an integrated heating element. In general, the particle sensors evaluate 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 according to this principle are generally referred to as resistive sensors and exist in a large number of embodiments, such as, for example DE 103 19 664 A1 . DE 10 2006 042 362 A1 . DE 103 53 860 A1 . DE 101 49 333 A1 and WO 2003/006976 A2 known. The designed as soot sensors sensor elements are commonly used to monitor diesel particulate filters. In the exhaust tract of an internal combustion engine, the particle sensors of the type described are usually incorporated in a protective tube, which simultaneously allows, for example, the flow of the particle sensor with the exhaust gas.

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 self-diagnosis of a particle sensor are for example 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 2012/0119759 A1 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 wire harness to be measured, may make self-diagnosis more difficult. Even deposits with unknown electrical properties, for example on electrode devices, can lead to superpositions of the desired measurement effect. 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 is still partially functional, in particular for example still 90%, in the case of a partial defect.

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 is proposed. In the context of the present invention, a sensor element is understood to mean any device which is suitable for qualitatively and / or quantitatively detecting the particles and which can generate an electrical measurement signal corresponding to the detected particles, for example with the aid of a suitable drive unit and suitably designed electrodes for example, 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. 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. Also 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.

In the context of the present invention, a carrier is basically understood to mean any substrate which is suitable for carrying the first electrode device and the second electrode device, and / or to which the first electrode device and the second electrode device 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. In the context of the present invention, the term electrode finger is basically understood to mean any shape of the electrode device whose dimension in one dimension significantly exceeds the dimension in at least one other dimension, for example at least a factor of 2, preferably at least a factor of 3, particularly preferably at least by a factor of 5. In the context of the present invention, a plurality is understood in principle to be an arbitrary 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 uA to 10 uA.

The at least one termination resistor may contact at least a portion of an electrode finger of the first electrode device and at least a portion 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 touch a section or several sections or all sections of all electrode fingers of the first electrode device and a section or several sections or all sections of all electrode fingers of the second electrode device.

The at least one terminating resistor can be applied to the carrier, for example, as a discrete component. However, the at least one terminating resistor can also be designed as a doping region described in more detail below within the carrier. In a particularly preferred embodiment of the sensor element according to the invention, the at least one terminating resistor can be designed such that in the absence of deposited particles, in particular in the absence of deposited soot or dust particles, preferably at the operating temperature of the sensor element, an electrode total resistance in a range of 1 MΩ to 150 MΩ , preferably in a range of 2 MΩ to 75 MΩ, and more preferably in a range of 5 MΩ to 50 MΩ. In the context of the present invention, the term "total electrode resistance" is understood to mean the electrical resistance of the circuit formed by the first electrode device, by the second electrode device, by the at least one terminating resistor and optionally by further components. Due to the low resistance of the two electrode devices, the total electrode resistance generally comprises essentially the terminating resistor or, in the case where a plurality of terminating resistors are present, a sum of the terminating resistors.

In the context of the present invention, the term "connected via a terminating resistor" basically means that each electrode finger of the first electrode device is in electrical contact with at least one electrode finger of the second electrode device by means of a terminating resistor.

The carrier may comprise as carrier material at least one ceramic material. In particular, the support may comprise an oxide ceramic, preferably alumina, 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 carrier may have a 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 include at least one doping region, wherein the doping region contacts at least a portion of an electrode finger of the first electrode device and at least a portion of an electrode finger of the second electrode device. 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. In the context of the present invention, the term touching is basically understood to mean 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 be doped in the at least one doping region with a doping material, wherein the doping material denotes the oxidic carrier material provided with the metallic impurity atoms. In particular, a concentration of the doping material in the at least one doping region can have a value of from 1 mol% to 100 mol%, preferably from 10 mol% to 90 mol% and particularly preferably from 20 mol% to 80 mol%. In a more congenial embodiment, the carrier material can thus be completely replaced by the doping material in the doping region.

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 ; Cr ₂ O ₃ ; MgO; MnO; Sm ₂ O ₃ ; Tb ₄ O ₇ ; Gd ₂ O ₃ ; Y ₂ O ₃ and any mixture of these materials.

In a particularly preferred embodiment, the support Al ₂ O ₃ and the doping 20 mol% to 100 mol% Fe ₂ O ₃ , preferably 40 to 80 mol% Fe ₂ O ₃ , in particular since the so-prepared ceramic mixed oxide on has a suitable electrical conductivity.

In a further preferred embodiment, the oxides Sm ₂ O ₃ ; Tb ₄ O ₇ ; Gd ₂ O ₃ and / or Y ₂ O ₃ suitable for doping. Here, the doping of a combination of at least two oxides may prove to be advantageous, for example, to realize the lowest possible temperature response of an electrical resistance of the doped carrier material within a selected Temperturfensters. The concentrations of the individual doping materials can each have a value of 0 mol% to 100 mol% in the at least one doping region; for example, a material combination Sm ₂ O ₃ / Tb ₄ O ₇ / Gd ₂ O ₃ / Y ₂ O ₃ im Ratio 25% / 50% / 0% / 25% can be 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 from 10 μm to 2 mm, preferably from 25 μm to 500 μm and particularly preferably from 50 μm to 250 μm. A thickness of the doping region may further 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.

In the context of the present invention, a width of the doping region is understood as meaning in principle the expansion of the doping region into that spatial dimension which is parallel to the carrier surface and perpendicular to the main extension direction of the electrode finger which the doping region contacts. In the context of the present invention, a length of the doping region is basically understood to mean the extent of the doping region into that spatial dimension which is parallel to the carrier surface and parallel to the main direction of extent of the electrode finger the doping area touched. In the context of the present invention, a thickness of the doping region is understood as meaning in principle the expansion of the doping region into that spatial dimension which extends perpendicular to the carrier 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 (Ωcm) ^-1 to 10 (Ωcm) ^-1 , preferably in a range of 1 × 10 ^-8 (Ωcm) ^-1 to 1 × 10 ^-2 (Ωcm) ^-1, and more preferably in a range of 1 × 10 ^-7 (Ωcm) ^-1 to 1 × 10 ^-3 (Ωcm) ^-1 ,

The electrode fingers of the first and / or the second electrode device may have a meandering course. In the context of the present invention, a meander-shaped course is basically understood to mean any course of the electrode device on the carrier surface which has at least one S-shape and / or at least one serpentine 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 can mesh in a comb-like manner.

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 within the sensor element may be constant or at least vary over a part of the sensor element. 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 can have a spacing from the electrode fingers of the second electrode device, wherein the distance within the sensor element can 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 terminating 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 terminating resistors can all lie in a region of the sensor element, which can also be referred to as the "cold region" of the sensor element and which is not acted on by the particles of the measuring gas. In this case, the cold region of the sensor element can in particular surround a side with connection contacts to a cable harness and can typically be separated from the hot exhaust gas by means of a sealing packing and therefore also be colder. However, the terminating resistors can at least partially lie in a region of the sensor element, which can also be referred to as the "hot region" of the sensor element and which is acted on by the particles of the measuring gas. Here the actual measuring range of the electrodes can be located; the printed electrode leads may be mounted in a transition region. Furthermore, the terminating resistors may be located at least partially in a control unit. The at least partial accommodation of the terminating resistors in the control unit permits a higher temperature stability compared with terminating resistors accommodated outside the control unit.

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 temperature stability compared to a terminator placed outside the controller. 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 may also be repeated be performed. 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.

1. a) Bereitstellen eines Trägers;
2. b) Aufbringen einer ersten Elektrodeneinrichtung und einer zweiten Elektrodeneinrichtung auf den Träger, wobei die erste Elektrodeneinrichtung und die zweite Elektrodeneinrichtung eine Mehrzahl von Elektrodenfingern aufweisen;
3. c) Erzeugen von mindestens einem Abschlusswiderstand auf dem Träger oder in dem Träger, wobei jeder Elektrodenfinger der ersten Elektrodeneinrichtung mit mindestens einem Elektrodenfinger der zweiten Elektrodeneinrichtung durch mindestens einen Abschlusswiderstand verbunden wird.

The process steps are:

1. a) providing a carrier;
2. b) applying a first electrode device and a second electrode device to the carrier, wherein the first electrode device and the second electrode device have a plurality of electrode fingers;
3. c) generating at least one terminating resistor on the carrier or in the carrier, wherein 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 terminating resistor.

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 abovementioned embodiments or according to one of the embodiments described in more detail below. Accordingly, for definitions and optional configurations, reference may be made largely to the description of the sensor element. However, other embodiments are possible in principle.

In step c), a thick-film technology can be used to apply the terminating resistor to the carrier, or a doping of the carrier to produce at least one doping region in the carrier can take place. When using the thick-film technology to produce the terminating resistor, the terminating resistor can be printed as a discrete component on the carrier, in particular on the ceramic substrate.

The proposed device and method have numerous advantages over known devices and methods. Due to the design of the electrode devices according to the invention, in particular the electrode structure, it may be possible to improve a self-diagnostic capability of a sensor element for detecting particles of a sample gas in a sample gas space compared to the prior art. In particular, it may be possible to monitor the electrode fingers of the first electrode device and the electrode fingers of the second electrode device individually, in particular with a frequency of at least 2 Hz. In particular, it may be possible to detect this defect in the case of a defect of an electrode finger or fewer electrode fingers and to continue to use the sensor element on the basis of the remaining, intact electrode fingers.

Furthermore, it may be possible to increase the accuracy, in particular the measurement accuracy, by means of the sensor element according to the invention over the prior art, in particular in the case of one or more defective electrode fingers. 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 makes it possible to achieve the highest possible differentiation between a defective area and an intact area in the event of a fault. In particular, it may be possible that with a high number of electrode fingers, the defect of a single electrode finger or of 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.

list of figures

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.

• 1 bis 3 verschiedene Ausführungsformen eines erfindungsgemäßen Sensorelements, wobei das Sensorelement in einer Draufsicht gezeigt ist;
• 4 Darstellung einer Abhängigkeit eines Elektrodengesamtwiderstands bzw. eines Eigendiagnosestroms von einer Anzahl defekter Elektrodenfinger in einem Sensorelement; und
• 5 bis 6 verschiedene Ausführungsformen eines erfindungsgemäßen Sensorelements in einer Querschnittsansicht.

Show it:

• 1 to 3 various embodiments of a sensor element according to the invention, wherein the sensor element is shown in a plan view;
• 4 Depicting a dependency of an electrode total resistance or a self-diagnostic current of a number of defective electrode fingers in a sensor element; and
• 5 to 6 various embodiments of a sensor element according to the invention in a cross-sectional view.

Embodiments of the invention

In the 1 to 3 are different embodiments of a sensor element according to the invention 110 for the detection of particles of a sample gas in a sample gas space shown in a plan view. 4 shows in the form of a diagram 130 a dependence of the total electrode resistance 128 and a dependence of the self-diagnosis current 126 from a number of defective electrode fingers 132 , where is the diagram 130 on the in 3 shown embodiment of a sensor element according to the invention 110 refers. In the 5 and 6 are different embodiments of a sensor element according to the invention 110 for detecting particles of a measuring gas in a measuring gas chamber 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 In particular, it may include one or more other functional elements not shown in the figures, such as electrodes, electrode leads and contacts, multiple layers, heating elements, electrochemical cells, or other elements such as shown in the above-mentioned prior art. Furthermore, the sensor element 110 be included for example in a protective tube, also not shown.

The sensor element 110 includes a carrier 112 , being on the carrier 112 a first electrode device 114 and a second electrode device 116 are applied. The first electrode device 114 and the second electrode means 116 have a plurality of electrode fingers 118 on, each electrode finger 118 the first electrode device 114 with at least one electrode finger 118 the second electrode device 116 by at least one terminator 120 connected is.

The at least one terminator 120 For example, as a discrete component on the carrier 112 be upset, like in 5 shown. The at least one terminator 120 However, it can also be described as a doping region described in more detail below 122 inside the vehicle 112 be designed as in 6 shown.

The carrier 112 may comprise at least one ceramic material as carrier material in these preferred embodiments. In particular, the carrier may 112 Alumina, especially Al ₂ O ₃ . Furthermore, the carrier 112 comprise at least one electrically insulating material.

The carrier 112 can have at least one doping region 122 include, wherein the doping region 122 at least a portion of an electrode finger 118 the first electrode device 114 and at least a portion of an electrode finger 118 the second electrode device 116 touches, as in 6 shown. In particular, the doping region 122 also a section or several sections of all electrode fingers 118 the first electrode device 114 and a portion or portions of all electrode fingers 118 the second electrode device 116 touch. The section of the electron finger 118 the first electrode device 114 and the portion of the electrode finger 118 the second electrode device 116 which the doping region 122 can touch, with the doping area 122 to be in electrical contact.

The carrier 112 may be in the at least one doping region 122 have introduced into the ceramic material foreign atoms, in particular metal atoms, wherein the metallic foreign atoms a Part of the in the ceramic material of the carrier 112 Replace contained metal atoms. As a result, the doping region 122 comprise at least one doped ceramic material, in particular an aluminum oxide doped with metal oxides. Other oxides are possible. The carrier 112 can thus in the at least one doping region 122 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 Fe ₂ O ₃ ; ZrO ₂ ; Cr ₂ O ₃ ; MgO; MnO, Sm ₂ O ₃ , Tb ₄ O ₇ , 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 a concentration of 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 may 112 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 of 10 microns to 2mm, preferably from 25 microns to 500 microns and more preferably from 50 microns to 250 microns. Furthermore, a length 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. 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 the doping region are in 6 shown. 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 (Ωcm) ^-1 to 10 (Ωcm) ^-1 , preferably in a range of 1 × 10 ^-8 (Ωcm) ^-1 to 1 × 10 ^-2 (Ωcm) ^-1, and more preferably in a range of 1 × 10 ^-7 (Ωcm) ^-1 to 1 × 10 ^-3 (Ωcm) ^-1 ,

The electrode fingers 118 the first electrode device 114 and / or the electrode fingers 118 the second electrode device 116 can have a meandering course 124 exhibit. 1 and 2 show two examples of a meandering course 124 , The electrode fingers 118 the first electrode device 114 and the electrode fingers 118 the second electrode device 116 can have a variety of other meandering courses. Furthermore, the electrode fingers 118 the first electrode device 114 and the electrode fingers 118 the second electrode device 116 mesh like a comb 1 - 3 . 5 and 6 shown.

The sensor element 110 can have at least two terminators 120 have, as in the 1 - 3 . 5 and 6 shown. The terminators 120 can have different values. The terminators 120 but they can all have the same value.

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

The terminators 120 can all be in one area of the sensor element 110 lie, which is not acted upon by the particles of the sample gas. The terminators 120 however, at least partially in a region of the sensor element 110 lie, which is acted upon by the particles of the sample gas. Furthermore, one or more of the existing terminating resistors can 120 are located in a control unit, not shown in the figures.

In the context of the present invention, an electrode total resistance is understood as meaning the electrical resistance of the circuit formed by the first electrode device, by the second electrode device, by the at least one terminating resistor and optionally by further components. The total electrode resistance may be in a range of 1 MΩ to 150 MΩ, preferably in a range of 2 MΩ to 75 MΩ, and more preferably in a range of 5 MΩ to 50 MΩ. Due to the low resistance of the two electrode devices, the total electrode resistance in usually the terminator or, in the case where there are multiple terminators, a sum of the terminators, hereinafter referred to as R _ges .

wobei die erste Elektrodeneinrichtung 114 eine Anzahl von n/2 Elektrodenfingern 118 aufweist, und wobei die zweite Elektrodeneinrichtung 116 ebenfalls eine Anzahl von n/2 Elektrodenfingern 118 aufweist, und wobei jeder Elektrodenfinger 118 der erste Elektrodeneinrichtung 114 mit mindestens einem Elektrodenfinger 118 der zweiten Elektrodeneinrichtung durch mindestens einen Abschlusswiderstand R_i (120) verbunden ist. Die Abschlusswiderstände R_i 120 können alle denselben Wert R₀ aufweisen. Für diesen Fall ergibt sich folgende Berechnung des Gesamtwiderstands R_ges $$Rges=1\text{/}\left({\displaystyle {\sum }_{i=1}^n\frac{1}{Ri}}\right)\text{ oder}$$

$$Rges\text{/}R0=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$n$}\right.$$

In particular, a total resistance R _{tot of} the existing terminating resistors can be determined 120 for the in 3 illustrated embodiment of a sensor element according to the invention 110 with a total of n electrode fingers 118 calculate as follows: $$RGes=1\text{/}\left({\displaystyle {\Sigma }_{i=1}^n\frac{1}{Ri}}\right)\text{.}$$

wherein the first electrode means 114 a number of n / 2 electrode fingers 118 and wherein the second electrode means 116 also a number of n / 2 electrode fingers 118 and wherein each electrode finger 118 the first electrode device 114 with at least one electrode finger 118 the second electrode device by at least one terminating resistor R _i ( 120 ) connected is. The terminating resistors R _i 120 may all have the same value R ₀ . For this case, the following calculation of the total resistance R _ges results $$RGes=1\text{/}\left({\displaystyle {\Sigma }_{i=1}^n\frac{1}{Ri}}\right)\text{or}$$

$$RGes\text{/}\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="DE102016220832A1\_0008.png"\; state="\{\{state\}\}">R</figure-callout>}0=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$n$}\right.$$

wobei die erste Elektrodeneinrichtung 114 eine Anzahl von n/2 Elektrodenfingern 118 aufweist, welche intakt oder zumindest teilweise defekt sein können, und wobei die zweite Elektrodeneinrichtung 116 ebenfalls eine Anzahl von n/2 Elektrodenfingern 118 aufweist, welche intakt oder zumindest teilweise defekt sein können, und wobei jeder Elektrodenfinger 118 der ersten Elektrodeneinrichtung 114 mit mindestens einem Elektrodenfinger 118 der zweiten Elektrodeneinrichtung durch mindestens einen Abschlusswiderstand R_i 120 verbunden ist: Die Abschlusswiderstände R_i 120 können alle denselben Wert R₀ aufweisen. Für diesen Fall ergibt sich folgende Berechnung des Gesamtwiderstands R_ges: $$Rges=1\text{/}\left({\displaystyle {\sum }_{i=1}^{n-m}\frac{1}{Ri}}\right)\text{ oder}$$

$$Rges\text{/}R0=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\left(n-m\right)$}\right.$$

Furthermore, the total resistance R _ges for the in 3 illustrated embodiment of a sensor element according to the invention 110 with a number of m defective electrode fingers 118 for a total of n electrode fingers 118 calculate as follows, $$RGes=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\left({\displaystyle {\Sigma }_{i=1}^{n-m}\frac{1}{ri}}\right)$}\right.\text{.}$$

wherein the first electrode means 114 a number of n / 2 electrode fingers 118 which may be intact or at least partially defective, and wherein the second electrode means 116 also a number of n / 2 electrode fingers 118 which may be intact or at least partially defective, and wherein each electrode finger 118 the first electrode device 114 with at least one electrode finger 118 the second electrode device is connected by at least one terminating resistor R _i 120: The terminating resistors R _i 120 can all have the same value R ₀ . For this case, the following calculation of the total resistance R _tot results: $$RGes=1\text{/}\left({\displaystyle {\Sigma }_{i=1}^{n-m}\frac{1}{Ri}}\right)\text{or}$$

$$RGes\text{/}\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="DE102016220832A1\_0008.png"\; state="\{\{state\}\}">R</figure-callout>}0=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\left(n-m\right)$}\right.$$

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

For self-diagnosis, at least at times a measuring voltage between the first electrode device 114 and the second electrode means 116 be created and a self-diagnostic current 126 and / or an electrode total resistance 128 can be measured. The self-diagnostic current 126 flows through the first electrode device 114 , the second electrode device 116 and the at least one terminator 120 , The self-diagnostic current 126 can be a measure of the functionality of the sensor element 110 and / or the quality of the sensor element 110 be.

4 shows an example of a diagram 130 in which the self-diagnostic current 126 depending on the number of defective electrode fingers 132 , as well as the total electrode resistance 128 depending on the number of defective electrode fingers 132 is shown. The diagram 130 in 4 refers to the in 3 shown embodiment of a sensor element 110 , A stream is posted 134 about the number of defective electrode fingers 132 , as well as a resistor 136 about the number of defective electrode fingers 132 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10319664 A1 [0003]
• DE 102006042362 A1 [0003]
• DE 10353860 A1 [0003]
• DE 10149333 A1 [0003]
• WO 2003/006976 A2 [0003]
• DE 102009028239 A1 [0004]
• DE 102009028283 A1 [0004]
• DE 2007046096 A1 [0004]
• DE 102006042605 A1 [0004]
• US 2012/0119759 A1 [0004]

Claims (12)

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, wherein the first electrode means (114) and the second electrode means (116) each comprise a plurality of electrode fingers (118), each electrode finger (118) passing the first electrode means (114) with at least one electrode finger (118) of the second electrode means (116) 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) comprises at least a portion of an electrode finger (118) of the first electrode device (114) and at least a portion of an electrode finger (12). 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, ZrO ₂ , Cr ₂ O ₃ , MgO, MnO, Sm ₂ O ₃ , Tb ₄ O ₇ , Gd ₂ O ₃ and Y ₂ O ₃ . Sensor element (110) according to the preceding claim, wherein the doping material is present in the at least one doping region (122) in a concentration of 1 mol% to 100 mol%. 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 μm. 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 has an electrical conductivity of 1 · 10 ^-9 (Ωcm) ^-1 to 10 (Ωcm) ^{- 1} has. Sensor element (110) according to one of the preceding claims, wherein the sensor element (110) has at least two terminating resistors (120). Sensor element (110) according to the preceding claim, wherein the at least two terminating resistors (120) each have different values from each other. Sensor element (110) after Claim 6 wherein the at least two terminating resistors (120) have the same value. Sensor element (110) according to one of the preceding claims, wherein the terminating resistor (120) is introduced into a control unit. Sensor element (110) according to one of the preceding claims, wherein an electrode total resistance representing at least a sum of a resistance of the first electrode means (114), a resistance of the second electrode means (116) and a total resistance R _{ges of} the at least one terminating resistor (120) Value from 1 MΩ to 150 MΩ. Method for producing a sensor element (110) for detecting particles of a measurement gas in a measurement 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.

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