WO2020126193A1

WO2020126193A1 - Particle sensor and method for producing same

Info

Publication number: WO2020126193A1
Application number: PCT/EP2019/080351
Authority: WO
Inventors: Radoslav Rusanov; Simon Schneider
Original assignee: Robert Bosch Gmbh
Priority date: 2018-12-20
Filing date: 2019-11-06
Publication date: 2020-06-25
Also published as: EP3899481A1; DE102018222541A1

Abstract

The invention relates to a particle sensor, comprising a particle charging device for charging particles in a fluid flow, a particle deflection device, which is arranged downstream of the particle charging device with respect to a flow direction of the fluid flow, for influencing the trajectories of charged particles, and a sensor device, which is arranged downstream of the particle deflection device with respect to the flow direction, for detecting information regarding charged particles. The sensor device has a sensitivity to the charged particles, which depends on the trajectory of the particular charged particle in the region of the sensor device.

Description

description

title

Particle sensor and manufacturing process therefor

State of the art

The disclosure relates to a particle sensor with a particle charging device for charging particles in a fluid stream.

The disclosure further relates to a method for producing a

Particle sensor with a particle charging device for charging particles in a fluid stream.

Disclosure of the invention

Preferred embodiments relate to a particle sensor with a particle charging device for charging particles in a fluid stream, one with respect to a flow direction of the fluid stream downstream of the

Particle charging device arranged particle deflection device for influencing the trajectories of charged particles, and one with respect to the flow direction downstream of the particle deflection device

arranged sensor device for recording information about charged particles, the sensor device having a sensitivity to the charged particles which is dependent on the trajectory of the respective charged particle in the area of the sensor device. This advantageously makes it possible to reduce a dependency of a measurement signal of the particle sensor that can be determined by means of the sensor device on the particle size, whereby e.g. an achievable accuracy for a particle number density determination is increased.

During an electrical charging of the particles which can be achieved by means of the particle charging device, according to the applicant's studies with their size increases, in preferred embodiments a mechanism counteracting this effect can be provided in an effective chain of the particle sensor by the combination of features mentioned above, so that an influence of the

Particle size can be reduced to the measurement signal of the sensor device or completely suppressed.

In further preferred embodiments it is provided that the

Sensor device has a sensitivity to the electrical charge of the charged particles, which is dependent on the trajectory of the respective charged particle in the area of the sensor device.

In further preferred embodiments it is provided that the

Sensor device works on the principle of influence, focusing on the

Sensor device or a sensing electrode of the sensor device

charged particles moving past have an influential effect on the

Exercise sensor device or its sensing electrode, which can be detected and also evaluated in further preferred embodiments.

For example, the fluid flow can be an exhaust gas flow from an internal combustion engine. For example, the particles can be soot particles, such as those that arise during the combustion of fuel by an internal combustion engine. The principle according to the embodiments can be used both for sensing particles formed as solids (e.g. soot particles, such as those contained in an exhaust gas stream of an internal combustion engine) and for sensing e.g. liquid particles (e.g. aerosol) can be used. In further preferred embodiments, a guide device for guiding the fluid flow along components of the particle sensor can be provided, for example a hollow cylindrical one

trained guide element, e.g. a pipe.

In further preferred embodiments it is provided that the

Particle deflection device is designed to move the charged particles at least in one of the flow direction

to influence different deflection direction, in particular the

Deflection direction is perpendicular to the flow direction. This enables a particularly efficient influencing of the movement of the charged particles. In further preferred embodiments it is provided that the

Particle deflection device is designed to generate a homogeneous electric field at least in regions, the field lines of which are parallel to the deflection direction.

In further preferred embodiments it is provided that the

Particle deflection device is designed to a degree of

To influence the movement of the charged particles, in particular dynamically, i.e. during the operation of the particle sensor, in the case of the generation of the i.w. homogeneous electric field e.g. by specifying the electric field strength.

In further preferred embodiments it is provided that the

Sensor device has a sensitivity to the charged particles, which is dependent on a position of the trajectory of the respective charged particle along the deflection direction, or a location-dependent

Sensitivity. This ensures that depending on the position of the trajectory of a particle - viewed along the deflection direction - the charged particle or its electrical charge is detected by the

Sensor device with a position-dependent sensitivity. In other words, in further preferred embodiments, charged particles deflected to different extents can thus have different “good”

(with different sensitivity to the charge of the particle) are detected by the sensor device.

In further preferred embodiments it is provided that the

Sensor device has at least one sensing electrode.

In further preferred embodiments it is provided that a differential area element (or the size of this differential

Surface element) of an electrode surface of the at least one sensing electrode along one or the deflection direction from a position along the

Direction of deflection depends. In further preferred embodiments it is provided that a

Electrode surface of the sensing electrode has a triangular shape, in particular the shape of a right-angled triangle.

In further preferred embodiments it is provided that a

Electrode surface of the sensing electrode has a shape which is delimited by two mutually orthogonal sections and a curve section, the course of which is proportional to 1 / y ² , where y represents a coordinate corresponding to the deflection direction, the coordinate axis being collinear with one of the sections.

In further preferred embodiments it is provided that the

Sensor device has at least one aperture. As a result, selectively charged particles can be removed from the fluid stream with special trajectories, in particular before they pass through the sensor device, as a result of which the removed particles are no longer used as a basis for the measurement by the sensor device. For example, in other preferred embodiments, the

Particle deflection device deflected particles are intercepted by means of the aperture before they reach the sensor device, so that this

particles comparatively strongly deflected by the particle deflection device are no longer taken into account in a measurement.

In further preferred embodiments it is provided that the

Sensing electrode has a segmentation into several partial areas, one or more of the partial areas, in particular optionally, can be interconnected.

Further preferred embodiments relate to a method for producing a particle sensor with a particle charging device for charging particles in a fluid stream, the method comprising the following steps: Providing a downstream of the particle charging device with respect to a flow direction of the fluid stream

Particle deflection device for influencing the trajectories of charged particles, and providing a sensor device arranged downstream of the particle deflection device with respect to the flow direction

Collection of information about charged particles, the Sensor device has a sensitivity to the charged particles, which is dependent on the trajectory of the respective charged particle in the area of the sensor device.

Further preferred embodiments relate to the use of the particle sensor according to the embodiments for determining a variable characterizing a number of particles in the fluid flow, in particular for determining a particle number density, in particular in an exhaust system of an internal combustion engine.

Further features, possible applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are shown in the figures of the drawing. All of the features described or illustrated form the subject matter of the invention, independently or in any combination

Summary in the claims or their relationship and regardless of their wording or representation in the description or in the drawing.

The drawing shows:

Figure 1 schematically shows a side view of a particle sensor according to

preferred embodiments,

FIG. 2 schematically shows a side view of a particle sensor according to further preferred embodiments,

Figure 3A,

3B, 3C each schematically an electrode geometry according to another

preferred embodiments, and

Figure 4 schematically shows a simplified flow diagram according to others

preferred designs.

FIG. 1 schematically shows a side view of a particle sensor 100 according to preferred embodiments. The particle sensor 100 has one

Particle charging device 110 for electrically charging particles P in a fluid flow A1, whereby charged particles P 'are obtained. In further preferred embodiments, the particle charging device 1 10 has a corona electrode 1 12 for generating a corona discharge 1 13, by means of which ions can be generated, through which the particles P can be charged.

In further preferred embodiments, the

Particle charging device 110 also have a different type of device for ion generation. The ions generated by the corona discharge 113 electrically charge the particles P in the fluid stream A1, either within the electric field of the corona electrode 1 13, e.g. on their way to an optional counter electrode 1 12 ', and / or diffusively, outside the field region 114 of the corona electrode 113. Depending on the charging mechanism, the electrical charge q achieved per particle P is linear (n = 1) to square in other preferred embodiments (n = 2) of one

Particle diameter d dependent, q = alpha ^* d ^A n, where alpha is one

Proportionality constant.

The particle sensor 100 further has a flow direction x of the fluid flow A1 downstream of the particle charging device 110

arranged particle deflection device 120 for influencing the

Trajectories of charged particles P ', and one with respect to the

Flow direction x downstream of the particle deflection device 120 arranged sensor device 130 for detecting information about charged particles P ', wherein the sensor device 130 has a sensitivity to the charged particles P' (or to the electrical charge q of the charged particles P '), which of the Trajectory of the respective charged particle P 'in the region B of the sensor device 130 is dependent, and is therefore location-dependent. This advantageously makes it possible to reduce a dependency of a measurement signal of the particle sensor that can be determined by means of the sensor device 130 on the particle size, as a result of which e.g. an achievable accuracy for a particle number density determination is increased.

While an electrical charging of the particles P which can be achieved by means of the particle charging device 110 increases according to the applicant's investigations, the size increases in preferred embodiments by the configuration 100 described above, which counteracts this effect Mechanism predictable, so that an influence of the particle size on the

Measurement signal of the sensor device 130 can be reduced or completely suppressed.

In further preferred embodiments it is provided that the

Sensor device 130 works according to the principle of influence, with charged particles P 'moving past sensor device 130 or a sensing electrode (not shown in FIG. 1) of sensor device 130

Influence the sensor device 130 or its sensing electrode, which can be detected and, in further preferred embodiments, also evaluated.

For example, the fluid flow A1 can be an exhaust gas flow from an internal combustion engine. For example, the particles P can be soot particles, such as those produced in the course of combustion of fuel by an internal combustion engine. The principle according to the embodiments can be used both for sensing particles formed as solids (e.g. soot particles, such as those contained in an exhaust gas stream of an internal combustion engine) and for sensing e.g. liquid particles (e.g. aerosol) can be used.

In further preferred embodiments, it is provided that at least some components 1 10, 1 12, 1 12 ″, 120, 130 of the particle sensor 100 are arranged on a surface 102 a of a carrier element 102, which is designed, for example, as a preferably planar ceramic substrate.

In further preferred embodiments it is provided that the

Particle deflection device 120 is designed to influence a movement of the charged particles P 'at least in a deflection direction y different from the flow direction x, the deflection direction y in particular being perpendicular to the flow direction x. This enables a particularly efficient influencing of the movement of the charged particles P '.

FIG. 2 schematically shows a side view of a particle sensor 100a according to further preferred embodiments. A particle stream AT having the particles P is fed to the particle sensor 100a in FIG. 2 from the left. A Ion source 1 10 'generates ions I (here also schematically illustrated by the sign “+”, but not limited to a positive electrical charge) for charging the particles P, as a result of which the charged particles P ′ are obtained in the charging region 1 14 first move further to the right in accordance with the flow direction x in FIG. 2, where they reach the particle deflection device 120. It should be noted that larger particles P1 can receive more charge than smaller particles P2 due to the charging process described.

The charged particles P ′, P1, P2 are deflected to different extents by the particle deflection device 120, in particular in accordance with their diameter-charge ratio, cf. the different trajectories T1, T2.

In further preferred embodiments it is provided that the

Particle deflection device 120 is designed, at least

to generate a homogeneous electric field 122 in regions, the field lines of which are parallel to the deflection direction y, e.g. similar to one

Plate capacitor.

In further preferred embodiments, the sensor device 130 detects the charged particles P1, P2 by means of its sensing electrode 132 on the basis of the mirror charge (influence effect) which arises from particles located in its region B, in particular above it.

In further preferred embodiments it is provided that the

Sensor device 130 has a sensitivity to the charged particles P ′, P1, P2, which is location-dependent or depends on a position of the trajectory T1, T2 of the respective charged particle along the deflection direction y. This ensures that depending on the position of the trajectory T1, T2 of a particle - viewed along the deflection direction y - the charged is detected

Particle or its electrical charge by the sensor device 130 with a position-dependent sensitivity. In other words, in further preferred embodiments, charged particles P1, P2 deflected to different degrees can thus be detected differently by “good” (ie, with different sensitivity with regard to the charge of the particle) by the sensor device 130. In further preferred embodiments it is provided that the

Sensor device 130 has at least one sensing electrode 132 on which the described influence of the charged particles P1, P2 takes place.

In further preferred embodiments, cf. 3A, it is provided that a differential surface element dA, dA 'of the electrode surface EF1 of the at least one sensing electrode 132 along the deflection direction y depends on a position along the deflection direction. In other words, the differential area element dA, which is arranged between the coordinates yO, y1 of a coordinate axis corresponding to the deflection direction y, has a different size (area) than the further differential area element dA ', which lies between the coordinates y1, y2 of the Deflection direction y corresponding coordinate axis is arranged. As a result, the further differential area element dA enables a stronger interaction with charged particles in the area dA ′ of the electrode area assigned to it (in relation to a movement of the particles along the flow direction x) than e.g. is the case with the differential area element dA.

In this way, in further preferred embodiments, lighter charged particles P2, which are more deflected by the particle deflection device 120 (trajectory T2), than heavier charged particles P1

(Trajectory T1), in the "more charge sensitive" areas d '

Electrode surface EF1 of the sensing electrode 132 are moved, whereas the heavier charged particles P1 are moved into the less “charge sensitive” areas dA of the electrode surface EF1 of the sensing electrode 132. In other words, the electrode surface EF1 of the sensing electrode 132 is designed in accordance with further preferred embodiments (here “linear”, cf. the width of the electrode surface EF1 that increases vertically downward in FIG. 3A) such that less strongly deflected particles P1 remain above it for a shorter time and related to their charge less to the measurement signal (e.g. characterized by a

Time integral over the charge influenced in the sensing electrode 132) of the sensor device 130 contribute as more strongly deflected particles.

In further preferred embodiments it is provided that a

Electrode surface EF1 of the sensing electrode 132 has a triangular shape, in particular the shape of a right-angled triangle, as described above with reference to FIG. 3A. In further preferred embodiments, cf. 3B, it is provided that the electrode surface EF2 of the sensing electrode 132 (FIG. 2) has a shape which is delimited by two mutually orthogonal sections S1, S2 (FIG. 3B) and a curve section C1, the course of which is proportional to 1 / y is ² , the parameter y representing a position on a coordinate axis y which is collinear with one of the lines, in the present case with the line S1. In other words, the horizontal extent of the electrode surface EF2 in FIG. 3B decreases with increasing values y according to 1 / y ² .

In further preferred embodiments, cf. 3C, it is provided that the sensing electrode 132 has a segmentation into a plurality of partial areas 132a, 132b,..., 132i, one or more of the partial areas, in particular optionally, being interconnectable in order to collectively result

Form electrode surface. This allows other preferred

Embodiments are dynamically set (during operation of the particle sensor) different resulting electrode shapes, which e.g. also have a location-dependent sensitivity.

For example, in further preferred embodiments, the

Subareas 132a, 132b, 132c, 132d, 132e, 132g are interconnected and used as an electrode area, the further subareas 132f, 132h, 132i being at least temporarily not used. This will be an effective one

3C (row R1) compared to the other rows R2, R3, which are each at larger y-coordinate values.

In further preferred embodiments, a distance of

Electrode surfaces or partial surfaces for fluid flow as a realization

different sensitivities are used because the measurement signal of the electrodes (surfaces or partial surfaces) decreases when the charged particles are at a greater distance from the electrode surface.

In further preferred embodiments it is provided that the

Particle deflection device 120 (FIG. 1) is designed to change a degree of influencing the movement of the charged particles P1, P2, P ', in particular dynamically, ie during the operation of the particle sensor 100, 100a, in the case of the generation of the generally homogeneous electric field 122 (FIG. 2), for example by specifying the electric field strength.

In further preferred embodiments it is provided that the

Sensor device 100a, cf. 2, (and / or the particle deflection device 120) has at least one aperture 140. As a result, selectively charged particles with special trajectories T2 can be removed from the fluid stream A1 ', in particular before they pass through the sensing electrode 132 of the sensor device 130, as a result of which the removed particles are no longer used as a basis for the measurement by the sensor device. For example, in other preferred embodiments, the

Particle deflection device 120 deflected particles P2 are intercepted by means of the aperture 140 before they reach the sensor device, so that these particles, which are deflected comparatively strongly by the particle deflection device, are no longer taken into account in a measurement.

In further preferred embodiments, the degree of influencing the movement of the charged particles P1, P2, P 'can be changed as already described, as a result of which it is also possible to control which particles - given the geometry and / or arrangement of the diaphragm 140 - through the diaphragm from the Fluid flow A1 'are removable.

Further preferred embodiments, cf. the simplified flow diagram of FIG. 4 relate to a method for producing a particle sensor with a particle charging device for charging particles in one

Fluid flow, the method comprising the following steps: providing 200 a particle deflection device arranged downstream of the particle charging device with respect to a flow direction of the fluid flow for influencing the trajectories of charged particles, and providing 202 one downstream with respect to the flow direction

Particle deflection device arranged sensor device for recording information about charged particles, the sensor device having a sensitivity to the charged particles, which is dependent on the trajectory of the respective charged particle in the area of the sensor device. Further preferred embodiments relate to the use of the particle sensor according to the embodiments for determining a one

Number of particles in the fluid flow A1, A1 'characterizing size,

in particular for determining a particle number density, in particular in an exhaust system of an internal combustion engine.

In further preferred embodiments, the particle sensor according to the embodiments can e.g. for particle filters for spark ignited and

self-igniting internal combustion engine can be used, e.g. for OBD (on board diagnosis) procedure. In addition, the use of the particle sensor according to the embodiments is possible in any other application in which a particle / aerosol concentration e.g. to be measured in a gas.

Further preferred embodiments and aspects are described below.

In further preferred embodiments, the electric field 122 (FIG. 2) of the particle deflection device 120 causes a deflection y of the particles, that is to say influencing their respective trajectory T1, T2, in accordance with their drift speed, y = vt, with the residence time t in the deflecting field 122 of strength E and the average drift velocity v = qE Iz, where z is the coefficient of friction of the particle P1 in question in the fluid flow A1 ',

in particular gas, z = Sd k, which is preferred in others

Embodiments depending on the properties of the fluid or fluid flow A1 'and the size of the particles P1 proportional, here proportionality coefficient

d, to the first, k = 1, to the second, k = 2, power of the particle diameter.

The deflection thus results in further preferred embodiments

In further preferred embodiments it is provided that

the sensing electrode consists of different sub-segments at least along the deflection direction y, as shown in FIG. 3C. In further preferred embodiments, the sub-segments can also be arranged in addition to the y arrangement along the x direction in order to differentiate the sensitivity to reach. For example, for a higher sensitivity at a position y, several segments can be switched on (or connected together).

For example, but not limited to, this may be a matrix arrangement, e.g. similar to Fig. 3C, but also a non-square matrix

(different number of rows / columns) is possible.

In further preferred embodiments it is provided that the

Sensor device 130 (FIG. 1) has a location-dependent sensitivity with regard to the charge of the particles, in particular has a variable sensitivity along the deflection direction y, as already described above with reference to FIGS. 2, 3A, 3B. This advantageously ensures that a deflection effect on the particles can also have an effect on the signal of the sensor device.

In further preferred embodiments it is provided that the variable sensitivity of the sensor device 130 along the deflection direction y alternatively or in addition to the specification of the shape of the electrode surface EF1, EF2 of its sensing electrode 130 by means of a corresponding circuitry and / or geometric arrangement, such as the distance to the fluid flow A1, A1 'is realized. This also advantageously ensures that a deflection effect on the particles can also have an effect on the signal of the sensor device.

In further preferred embodiments it is provided that the

Sensing electrode 132 is linear (m = 1), so that the sensitivity R of the electrode depends on the location y R = ßy ^m , where ß a

Proportionality constant. In further preferred embodiments, the measurement signal S results from the charge q and the number density N of the particles P 'in the region B (FIG. 2) or above the sensing electrode 132 and from the sensitivity R at the position y of the sensing electrode 132, S = qNR.

Using the above equations, this results for the measurement signal S according to further preferred embodiments

where y was introduced here as a summarizing proportionality constant. With a corresponding choice of the exponent m = -n / (nk) according to further preferred embodiments, there is no result for the measurement signal S.

Depending more on the particle size of the charged particles,

For example exponents according to further preferred embodiments of (n _a , k _a ) = (1, 2), (n, k _b ) = (2, 1), the result

Electrode sensitivity exponents of m _a = 1, m _b = -2. According to further preferred embodiments, these can be realized, for example, with electrode geometries corresponding to FIGS.

In further preferred embodiments, the electrode geometry of the sensing electrode 132 (FIG. 2) can be known if the present one is known

Charging mechanism for the particles P can be selected accordingly and thus e.g. a sensor signal S can be realized, which is no longer from the

Particle size, but only depends on the particle number density.

In further preferred embodiments, the electrode arrangement can be dynamically adapted, e.g. if the charging mechanism changes during operation, e.g. when modifying the corona tension. For this purpose, the sensing electrode 132 (FIG. 2) can consist of several switchable segments, cf. Figure 3C.

For example, In further preferred embodiments, a matrix arrangement of electrode (partial) surfaces (FIG. 3C), an effective electrode surface of any shape can be approximated by appropriate wiring. This allows the sensor behavior to be adjusted during operation.

A further possibility according to further preferred embodiments to make the sensitivity of the sensor device 130 dependent on the deflection (trajectories T1, T2) of the charged particles P ′, P1, P2 is to use an aperture 140, cf. Fig. 2.

In further preferred embodiments, the at least one

Sensing electrode 132 instead of the present with reference to FIGS. 2, 3A, 3B, the planar shape depicted by way of example can also be non-planar, for example in the form of a ring (for example similar to an outer surface of a circular cylinder). The variants described above with reference to FIGS. 1 to 4 apply correspondingly to such embodiments.

In further preferred embodiments, one or more of the following advantages are achieved: no or slight dependence of the sensor signal on the particle size, a particle number density can be calculated from the measurement signal.

Claims

Expectations

1. Particle sensor (100; 100a) with a particle charging device (110) for charging particles (P) in a fluid stream (A1), one with respect to a flow direction (x) of the fluid stream (A1) downstream of the

Particle charger (110) arranged

Particle deflection device (120) for influencing the trajectories (T1, T2) of charged particles (P '; P1, P2), and one with respect to the

Flow direction (x) downstream of the particle deflection device (120) arranged sensor device (130) for detecting information about charged particles (P '; P1, P2), the sensor device (130) being sensitive to the charged particles (P'; P1, P2 ), which is dependent on the trajectory (T1; T2) of the respective charged particle (P '; P1, P2) in the area (B) of the sensor device (130).

2. Particle sensor (100; 100a) according to claim 1, wherein the

Particle deflection device (120) is designed to influence a movement of the charged particles (P ′) at least in a deflection direction (y) that is different from the flow direction (x), the deflection direction (y) in particular being perpendicular to the flow direction (x).

3. particle sensor (100; 100a) according to claim 1, wherein the

Particle deflection device (120) is designed to generate, at least in regions, a homogeneous electric field (122) whose field lines are parallel to the deflection direction (y).

4. Particle sensor (100; 100a) according to at least one of the above

Claims, wherein the sensor device (130) has a sensitivity to the charged particles (P '), which is dependent on a position of the trajectory (T1; T2) of the respective charged particle (P') along the deflection direction (y).

5. particle sensor (100; 100a) according to at least one of the preceding claims, wherein the sensor device (130) at least one

Sensing electrode (132).

6. particle sensor (100; 100a) according to claim 5, wherein a differential

Surface element (dA, dA ') of an electrode surface (132; EF1; EF2) along one or the deflection direction (y) from a position along the

Direction of deflection (y) depends.

7. particle sensor (100; 100a) according to at least one of claims 5 to 6, wherein an electrode surface (132; EF1; EF2) of the sensing electrode (132) has a triangular shape, in particular the shape of a right angle

Triangular.

8. particle sensor (100; 100a) according to at least one of claims 5 to 7, wherein an electrode surface (132; EF1; EF2) of the sensing electrode (132) has a shape which by two mutually orthogonal paths (S1,

S2) and a curve section (C1) is limited, the course of which is proportional to 1 / y ² , where y represents a coordinate corresponding to the deflection direction (y).

9. Particle sensor (100; 100a) according to at least one of the above

Claims, wherein the sensor device (130) has at least one diaphragm (140).

10. Particle sensor (100; 100a) according to at least one of the above

Claims, wherein one or the sensing electrode (132) has a segmentation into a plurality of partial areas, one or more of the partial areas being interconnectable, in particular optionally.

1 1. Method for producing a particle sensor (100; 100a) with a

Particle charging device (1 10) for charging particles (P) in a fluid stream (A1), the method comprising the following steps:

Providing (200) with respect to a flow direction (x) of the

Fluid flow (A1) downstream of the particle charging device (110) arranged particle deflection device (120) for influencing the trajectories (T1, T2) of charged particles (P '), and providing (202) one with respect to the flow direction (x) downstream of the Particle deflection device (120) arranged sensor device (130) for detecting information about charged particles (P '), the sensor device (130) having a sensitivity to the charged particles (P'), which is determined by the trajectory (T 1; T2) of the respective charged particle (P ') in the area (B) of the sensor device (130).

12. Use of the particle sensor (100; 100a) according to at least one of claims 1 to 10 for determining a number of particles in the

Fluid flow (A1) characterizing variable, in particular for determining a particle number density, in particular in an exhaust system of an internal combustion engine.