Sensor for detecting conductive particles

Abstract

The present invention relates to a sensor (10) for detecting conductive particles in a gas flow, the sensor comprising a substrate (15) having a cubic or cylindrical shape having two front sides (17, 18), wherein a gas flow direction (G) is defined to extend in a direction from a first front side (17) to a second front side (18), wherein a resistive electrode structure (30) comprising at least two electrodes (31, 32) is formed on at least one surface (16, 19) of the substrate (15), the at least two electrodes (31, 32) being electrically isolated from each other, characterized in that, relative to the gas... In the direction of flow (G), a first electrode (31) is arranged in a first section (21) of the sensor (10) and is designed such that the first electrode (31) acts as an adsorption electrode, wherein a sensor detection area (40) is formed in a second section (22) of the sensor (10), wherein the sensor detection area (40) is formed by a portion (33) of the first electrode (31) and a portion (34) of a second electrode (32) spaced apart from the portion (33) of the first electrode (31), wherein the second electrode (32) is at least partially formed in a third section (23) of the sensor (10).

Description

Technical Field

[0001] This invention relates to a sensor for detecting conductive particles in a gas stream, the sensor comprising a substrate having a cubic or cylindrical shape, the cubic or cylindrical shape having a front side. Furthermore, this invention relates to a sensor system in which the sensor of this invention is included in a housing. Additionally, this invention relates to the use of the sensor of this invention or the sensor system of this invention. Background Technology

[0002] Different designs of particulate sensors, especially soot sensors, are known in the prior art. For example, such a soot particulate sensor is described in WO2011 / 106625A1, which consists of two interdigitated electrodes. Soot particles in the exhaust gas settle onto the surface of the soot particulate sensor and bridge the two electrodes. As the soot coverage increases, the resistance between the electrodes decreases. Measuring the resistance between the electrodes is a measurement of the soot particle concentration in the measured exhaust gas flow.

[0003] WO 2018 / 115054A1 also describes a sensor for detecting conductive particles and / or polarizable particles. An electrode layer is formed on a substrate. The electrode layer has at least two spatially separated and interlocked electrodes.

[0004] The electrode layer shape disclosed in WO 2018 / 115054A1 is produced, for example, by means of a laser ablation step. Because the electrode shape is relatively complex, many consecutive laser ablation steps are required to produce the electrode. Therefore, the production of particle sensors known in the prior art is relatively complex.

[0005] Figure 1 The image exemplifies a sensor system known in the prior art. Figure 1 A side view of a prior art sensor system 1 is shown. An electrode system 3 is formed on a substrate 2. The electrode system 3 consists of two interdigitated electrodes 4 and 5, i.e., the fingers of the first comb electrode 4 and the fingers of the second comb electrode 5 are shown in this side view. The sensor 6 thus formed is located in a housing 7.

[0006] Figure 1 The electric field formed by the comb-shaped electrodes 4 and 5 and the housing 7 is shown. Charged particles flowing into the housing 7 in the direction of arrow G pass through the periodically changing electric field while traversing the interdigitated capacitor structure (IDC). Therefore, the net force acting on the charged particles toward the electrode structure or (depending on the sign of the charge) toward the housing is relatively small compared to the electrode structure that generates a unidirectional field.

[0007] Based on the aforementioned prior art, the object of the present invention is to provide a further developed sensor for detecting conductive particles that is easier to manufacture. However, the sensor should at least have the same sensitivity and robustness as those known to incorporate such sensors made with interdigitated electrodes. Preferably, the sensitivity and robustness of the sensor should even be improved compared to the prior art.

[0008] Furthermore, the objective of this invention is to specify a further developed sensor system and possible uses of the sensor according to the invention. Summary of the Invention

[0009] According to the present invention, the problem is solved by a sensor for detecting conductive particles in a gas flow, a sensing system including the sensor, and the use of the sensor and / or sensing system for detecting soot particles in the exhaust system of a vehicle.

[0010] The present invention is based on the idea of ​​specifying a sensor for detecting conductive particles in a gas flow. The sensor includes a substrate having a cubic or cylindrical shape with two front sides. The gas flow direction is defined as extending from a first front side toward a second front side. The sensor according to the invention has a resistive electrode structure. This resistive electrode structure has at least two electrodes and is formed on at least one surface of the substrate. The at least two electrodes are electrically isolated from each other. Conductive particles should be specifically understood as charged particles.

[0011] The gas flow direction is specifically defined as extending from the first front side of the substrate to the second front side of the substrate. The adsorption electrode is switchable to enable it to attract charged particles.

[0012] According to the present invention, the first electrode is arranged in the first section of the sensor relative to the gas flow direction and is designed such that the first electrode acts as an adsorption electrode.

[0013] A sensor detection area is formed in a second segment of the sensor, and this sensor detection area is formed by a portion of the first electrode and a portion of a second electrode spaced apart from that portion of the first electrode. The second electrode is formed, at least segmentally, in a third segment of the sensor.

[0014] In other words, the sensor can be divided into at least three sections. The first, second, and third sections are arranged in the direction of gas flow.

[0015] The sensor according to the present invention is based on a resistive electrode system and corresponding analysis or detection of the resistance to be detected.

[0016] In one embodiment of the invention, the resistive electrode structure is formed only on one surface of the substrate. This embodiment is known in the prior art.

[0017] Alternatively, resistive electrode structures can be formed on both sides of the substrate. The advantage of this implementation is that it detects not only particles flowing along the first sensor side, but also particles flowing along the other sensor side. The sensor sensitivity can be improved due to the resistive electrode structures on both sides of the substrate.

[0018] The corresponding first electrodes of the two resistive electrode structures can be contacted together or separately. Furthermore, the corresponding second electrodes of the resistive electrode structures can be contacted together or separately.

[0019] This embodiment, which includes two resistive electrode structures, is particularly suitable for cubic substrates. If the substrate has a cylindrical shape, then, if the substrate is a hollow cylinder, the resistive electrode structures can be formed on both sides.

[0020] The first electrode of the sensor is preferably the electrode that the particles pass through first as they flow along the sensor. Charged particles in the gas flow that have a charge opposite to that of the first electrode are deflected toward the first electrode or electrostatically attracted by it as they flow past it.

[0021] The first electrode therefore has two functions:

[0022] Due to its design as an adsorption electrode, the first electrode attracts charged particles with polarity opposite to that of the electrode itself. This adsorption of charged particles increases the particle density on the first electrode, particularly in the sensor's detection region.

[0023] Another function of the first electrode is to form a resistive sensor together with at least the second electrode. This resistive sensor allows for the detection of particles deposited in the sensor's detection area.

[0024] In an unexpected way, the sensor of the present invention, having the above-described design, improves the sensitivity of the sensor.

[0025] In one embodiment of the invention, the structure of the first electrode in the first segment of the sensor should be understood such that the entire first electrode in the first segment is configured as an adsorption electrode. In other words, in this case, not only do individual segments or portions of the first electrode act as adsorption electrodes, but the entire first electrode located in the first segment acts as an adsorption electrode.

[0026] Specifically, in this embodiment of the invention, a single comb-like segment or a single finger of the first electrode should not be construed as an adsorption electrode.

[0027] In another embodiment of the invention, the sensor has only a single sensor detection area, which is formed within a second segment of the sensor. In other words, no additional or supplementary sensor detection areas are constructed within the sensor other than the sensor detection area formed within the second segment.

[0028] Preferably, there is no sensor detection area in the first section of the sensor. In other words, the adsorption electrode is preferably arranged in the first section, and no means of resistivity detection for charged particles, especially charged soot particles, is provided.

[0029] There are several options to avoid forming a sensor detection area in the first segment of the sensor.

[0030] First, it is possible to avoid forming a second electrode or a section of a second electrode in the first section of the sensor.

[0031] Furthermore, a passivation layer can be applied to the electrodes formed in the first segment of the sensor and the free space between them. If a passivation layer is formed, conductive particles in that area will not be detectable, even between adjacent electrodes.

[0032] Another possibility is that the distance between the two electrodes is chosen to be so large that detection of conductive particles, especially soot particles, cannot be performed in the region between adjacent electrodes or electrode segments. It is known that in order to detect conductive particles between two electrodes, the distance between the electrodes or electrode segments must be chosen such that fine filaments of particles, especially soot filaments, are preferably formed between the electrodes or electrode segments.

[0033] Furthermore, the two electrodes can be aligned parallel to the gas flow. This electrode design will suppress the formation of charged particle filaments between the electrodes.

[0034] Considering the gas flow, the adsorption electrode is placed in front of the sensor's detection area. The attraction potential of the adsorption electrode will force charged particles carried in the gas flow toward the adsorption electrode. Particles may land on the adsorption electrode and may be expelled from there. Volatile particles on or slightly above the adsorption electrode will be removed by the gas flow toward the sensor's detection area, contributing to a change in resistance between the first and second electrodes.

[0035] The area covered by the adsorption electrode (ASE) is larger than the area between the first and second electrodes in the sensor detection region (ADR). The ratio of ASE to ADR is at least 20, preferably at least 50, and most preferably at least 100. The large ASE generation will force charged particles toward the large-area and uniform electric field of the adsorption electrode.

[0036] Adsorption electrodes can uniformly cover a specific area of ​​the substrate. However, they can also intersect the uniform area via grooves or lines. The area formed by the intersections is relatively small compared to the area of ​​the remaining adsorption electrode. Therefore, the intersections will not significantly alter the uniform electric field generated by the adsorption electrodes. Intersections may be advantageous for structuring adsorption electrodes. A possible structure for an adsorption electrode formed by intersections is, for example, a U-shaped meandering structure used in heating elements or temperature sensors.

[0037] Furthermore, the sensor design of this invention is easier to manufacture than electrode arrangements known in the prior art. This is particularly applicable to interdigital capacitor structures known in the prior art.

[0038] The application of the sensor for detecting charged particles according to the present invention is the same as that of known resistive sensors. During a measurement cycle, the resistance between the first and second electrodes is determined as a function of time. This is used as a measure of the particle concentration in the gas stream. When the particle occupancy on the resistive electrode structure has reached a previously defined threshold, the sensor, particularly the resistive electrode structure, is cleaned during a regeneration cycle. This is done, for example, by heating the resistive electrode structure. The conductive particles on top of the resistive electrode structure are removed again by heating. A new measurement cycle can then begin.

[0039] The first electrode and / or the second electrode are preferably designed as heating elements.

[0040] In another embodiment of the invention, the first electrode and / or the second electrode may be segmentally coated with a passivation layer, wherein at least the sensor detection area is formed without the passivation layer. The advantage of forming such a passivation layer is that the sensor can be reliably used even in high temperatures and corrosive gases.

[0041] In a particularly easy-to-manufacture embodiment of the invention, the first and second electrodes are each fabricated as rectangular electrodes. This allows the electrode structure to be applied, for example, by means of screen printing technology. Continuous fine structuring of the electrodes, especially in the sensor detection region, can be accomplished using ablation lasers.

[0042] In another embodiment of the invention, the first electrode and the second electrode are arranged parallel to each other at least in segments, and the second electrode surrounds the first electrode at least in segments transverse to the gas flow direction. Preferably, the second electrode surrounds the first electrode at least in a third segment of the sensor. This surrounding of the first electrode results in the formation of a sensor detection region having, for example, a slit-shaped recess transverse to the gas flow direction.

[0043] The gap between the first and second electrodes in the sensor detection area is oriented substantially perpendicular to the gas flow direction and is preferably slit-shaped. The width of the gap is at most 200 μm, preferably at most 100 μm, and most preferably at most 70 μm. Alternatively, the width of the gap may be at least 10 μm, preferably at least 20 μm, and most preferably at least 30 μm.

[0044] In a preferred embodiment, the gap width between the first and second electrodes in the first segment is at least twice, preferably three times, and most preferably at least four times larger than the gap width between the first and second electrodes in the sensor detection area. Therefore, this prevents or reduces the detection of particles in the first segment.

[0045] The first electrode can be rectangular or U-shaped. For example, the second electrode can be U-shaped or L-shaped.

[0046] In another embodiment of the invention, the first electrode includes a structured line for structuring the first electrode in the connection region, particularly in the meandering portion.

[0047] If the first electrode is designed as a heating element, then designing the first electrode as a meandering portion is particularly suitable. The first electrode can also be used as a temperature sensor, especially when the electrode is made of a material with a large temperature coefficient. In another embodiment of the invention, the sensor has at least a third electrode. The third electrode is formed between the first and second electrodes or is formed to at least partially encapsulate the second electrode. The third electrode can be used as an auxiliary electrode, which is individually addressed or electrically connected to the first electrode to optimize the adsorption of conductive particles in the gas flow.

[0048] It is also possible for the first electrode and / or the second electrode to have peaks in the sensor detection region. If both the first electrode and the second electrode have peaks in the sensor detection region, it is advantageous for the peaks of the two electrodes to be opposite each other and facing each other.

[0049] Field enhancement can be generated by forming peaks in the sensor detection region. This is used to improve the sensitivity of the sensor. In one embodiment of the invention, it is possible that segments of the first electrode and / or the second electrode in the sensor detection region are structured by etching or laser ablation, such that the formed peaks are used for field enhancement.

[0050] The described passivation layer is made of an electrically insulating material and is produced, for example, by screen printing or aerosol deposition (ADM). Preferably, the passivation layer is a metal oxide layer or a glass layer. If the passivation layer is a glass layer, it can be applied to the electrode segment to be covered by screen printing in the form of a glass paste.

[0051] The sensor detection area may be at least segmented without a passivation layer, such that only the end faces of the first electrode and the second electrode are without a passivation layer.

[0052] In a similarly suitable embodiment of the invention, the sensor detection area may be formed such that the end faces of portions of the first and second electrodes, as well as the surfaces of the electrode segments, are partially exposed. This embodiment of the invention improves the growth of the formed granular filaments from the first electrode to the second electrode.

[0053] In another embodiment of the invention, it is possible that the end faces of the sections of the first and second electrodes are only partially free of a passivation layer. For example, a passivation layer may be coated on the portion of the end face adjacent to or adjacent to the substrate. In this case, only the upward-facing sections of the end faces of the first and second electrodes are free of a passivation layer.

[0054] In another embodiment of the invention, the first electrode has a longitudinal extension from 0.5 mm to 100 mm, particularly from 3 mm to 50 mm, and especially preferably from 5 mm to 30 mm.

[0055] And / or a width extension of 0.5 mm to 50 mm, particularly from 1.5 mm to 30 mm, especially preferably from 3 mm to 10 mm, wherein the longitudinal extension is in the gas flow direction (G) and the width extension is perpendicular to the gas flow direction (G).

[0056] The specified longitudinal and / or width extension of the first electrode provides a sufficiently large electrode area, enabling the first electrode to reliably function as an adsorption electrode.

[0057] In a stratified gas flow, charged particles need a certain amount of time to flow past the first electrode, so that even such charged particles that are farther away from the first electrode can still collide with it.

[0058] In a particularly preferred embodiment of the invention, the sensor according to the invention has a resistive electrode structure that does not have an interdigitated capacitor (IDC) structure. Specifically, the IDC structure should be understood as an arrangement of interlocking electrodes. In this arrangement of the electrode structure (IDC structure), each electrode typically has a comb-like structure, whereby the electrodes are positioned relative to each other such that the combs interlock. In other words, the comb teeth of the first electrode are each located in the space between two comb teeth of the second electrode, and vice versa.

[0059] Furthermore, for this type of electrode arrangement (IDC structure), it is possible that each electrode has finger-like segments. The fingers of the first electrode are intended to be positioned in the space between the two fingers of the second electrode, and vice versa.

[0060] According to the invention, the formation of an IDC structure should therefore not be performed, especially in the option of forming a comb or finger-like structure for the two electrodes. Specifically, it is important for the invention not to form such an IDC structure, particularly in the first segment of the sensor.

[0061] Another aspect of the invention relates to a sensor system including a sensor according to the invention. The sensor is disposed in a conductive housing having a gas inlet opening and a gas outlet opening. The sensor is disposed in the housing such that a first end face of the substrate faces the gas inlet opening and a second front side faces the gas outlet opening.

[0062] During the measurement mode of the sensor system, a first electric field is formed between the first electrode and the conductive housing. This first electric field is unidirectional, and a second electric field is formed between the first electrode and the second electrode.

[0063] In one embodiment of the invention, the housing is designed as an inner tube, which is arranged within an outer tube.

[0064] In another embodiment of the invention, the outer tube has an inlet opening, such as a slotted inlet opening, which is formed in the side surface of the outer tube in the longitudinal direction.

[0065] Another aspect of the invention relates to the use of the sensor and / or sensor system according to the invention for detecting carbon soot particles in the exhaust system of a vehicle.

[0066] In conjunction with the sensor system according to the invention and / or with respect to its use according to the invention, there are advantages similar to those already mentioned with respect to the sensor according to the invention. Attached Figure Description

[0067] The following schematic diagram illustrates aspects of the invention to improve understanding of the invention in conjunction with some exemplary illustrations, wherein

[0068] Figure 1 This illustrates a sensor based on existing technology;

[0069] Figure 2a and Figure 2b A top view of the sensor according to the present invention is shown;

[0070] Figure 3 A side view of another embodiment of the sensor according to the present invention is shown;

[0071] Figure 4 The basic function of the sensor according to the invention within the housing is shown;

[0072] Figures 5a to 5j A top view showing a further design of the sensor of the present invention is shown;

[0073] Figures 6a to 6d A top view and cross-sectional view of a further embodiment of the sensor according to the invention are shown, wherein a passivation layer is formed in a different manner;

[0074] Figures 7a to 7d illustrate different implementations of a sensor with a cylindrical substrate;

[0075] Figure 8a and Figure 8b A top view of a specific embodiment of the sensor in the sensor detection area is shown;

[0076] Figures 9a to 9g A cross-sectional view of the formation of an electrode segment in the sensor detection region is shown, in which a passivation layer is partially applied; and

[0077] Figure 10 A sensor system according to the present invention is shown. Detailed Implementation

[0078] The same reference numerals in the following figures are used for parts that have the same or similar functions.

[0079] Figure 2a and Figure 2b A first simplified embodiment of a sensor 10 according to the present invention is shown. Each sensor 10 is based on a cubic substrate 15. Figure 2a and Figure 2b A top view of sensor 10 is shown. This top view is a top view of surface 16 of substrate 15. Furthermore, the gas flow direction G is shown. This gas flow direction extends from the first front side 17 to the second front side 18.

[0080] The sensor 10 can be divided into three sections 21, 22 and 23. Starting from the first front side 17 of the sensor 10, the first section 21, the second section 22 and the third section 23 are arranged one after another in the gas flow direction G.

[0081] The first electrode 31 is located in the first segment 21 of the sensor 10. The first electrode 31 acts as an adsorption electrode.

[0082] A sensor detection region 40 is formed in the second segment 22 of the sensor 10, which is also shown. The sensor detection region 40 is formed by a portion 33 of the first electrode 31 and a portion 34 of the second electrode 32, whereby the two portions 33 and 34 are spaced apart from each other.

[0083] The second electrode 32 is formed in the third segment 23 of the sensor 10.

[0084] As can be seen, in this example, the longitudinal extension of the first electrode 31 is greater than the longitudinal extension of the second electrode 32. This elongated shape of the first electrode 31 provides a particularly effective adsorption electrode.

[0085] The sensor 10 has a resistive electrode structure 30, which enables the detection of conductive particles flowing in the gas flow direction G in the sensor detection area 40 according to known methods.

[0086] Figure 2b An embodiment of another simple construction of the sensor 10 according to the invention is shown. Edges 24 are formed, at least in segments, on the surface 16 of the substrate 15. The edges 24 extend from a first segment 21 of the sensor 10 to a third segment 23.

[0087] As can be seen in the example shown, the second electrode 32 is much shorter than the first electrode 31. In other words, in order to form the sensor detection area 40, a large extension of the second electrode 32 in the longitudinal direction or the gas flow direction G is not required.

[0088] Figure 3 Another embodiment of the sensor 10 according to the present invention is shown. The substrate 10 has resistive electrode structures 30 on both the first surface 16 and the second surface 19. Each of the two electrode structures 30 includes a first electrode 31 and a second electrode 32.

[0089] The advantage of this implementation is that it detects not only conductive particles flowing through the first surface 16 (i.e., the upper side of the sensor 10), but also conductive particles flowing along the second surface 19 or the lower side of the sensor 10 in the gas flow direction G.

[0090] The arrangement of the resistive electrode structure 30 on the first surface 16 and the second surface 19 provides a resistive sensor 10 with improved sensitivity. The first electrode 31 can be switched together or separately. The second electrode 32 can also be switched separately or individually.

[0091] Figure 4 The operating mode of the sensor 10 or sensor system 80 according to the present invention is shown. The sensor 10 according to the present invention is located in a conductive housing 85. In a side view, a first electrode 31 and a second electrode 32 can be seen. In addition, a sensor detection area 40 is formed. In the gas flow direction G, the second electrode is at least partially located behind the first electrode 31. The two electrodes 31 and 32 are electrically insulated from each other.

[0092] Compared to the housing 85, the first electrode 31 is at a positive or negative potential. The housing 85 and the second electrode 32 are at opposite potentials. The second electrode 32 and the housing 85 may be at the same potential. For example, they may be at ground potential.

[0093] Figure 4 The narrow arrows shown indicate the direction of the electric field between the first electrode and the housing 85, and between the first electrode 31 and the second electrode 32.

[0094] In other words, a first electric field 91 is formed between the first electrode 31 and the housing 85, and a second electric field 92 is formed between the first electrode 32 and the second electrode 31. Figure 1 Compared to the prior art shown, the first electric field is unidirectional.

[0095] Conductive particles in the gas flow that have a charge opposite to that of the first electrode 31 are biased toward the first electrode 31 or electrostatically attracted by the first electrode 31 when they flow past the first electrode 31.

[0096] Therefore, the first electrode 31 serves as an adsorption electrode, and further increases the particle density located on the first electrode 31, particularly in the sensor detection region 40. The second electrode 32 is combined to form a resistive electrode structure 30, enabling the detection of particles deposited in the sensor detection region 40.

[0097] With From Figure 1 Compared to known sensor implementations, such as Figure 4 The electric field generated by sensor 10 is unidirectional and uniform. Therefore, the force acting on the charged particles attracted by the first electrode 31 is greater than that acting on the charged particles attracted by the first electrode 31. Figure 1 The forces associated with the IDC structure shown. Therefore, with Figure 1 Compared to the embodiment shown, more charged particles are deposited on the flat first electrode 31.

[0098] Additionally, near-surface particles are conveyed to the sensor detection region 40 between the first electrode 31 and the second electrode 32. There, the particles can form conductive particle filaments, which reduce the resistance between the first electrode 31 and the second electrode 32.

[0099] Figures 5a to 5j Different embodiments of the resistive electrode structure 30 are shown.

[0100] according to Figure 5a The first electrode 31 is rectangular. On the other hand, the second electrode 32 has a U-shape, thereby at least segmentally surrounding the first electrode 31. In the region of the first front side 17, the first electrode 31 is not surrounded by the second electrode 32. Furthermore, the second electrode 32 can be designed as a heating circuit. The U-shaped second electrode 32 is designed as a circulating heating circuit. Both ends of the U-shaped second electrode 32 and the first electrode 31 can be individually electrically contacted at the first front side 17.

[0101] exist Figure 5bIn this design, the first electrode 31 is again designed as a rectangular electrode. The second electrode 32 has an L-shaped shape, wherein a short L-shaped segment 35 is formed in the third segment 23 of the sensor 20. The first electrode 31 and the second electrode 32 extend parallel to each other at least segmentally. Transverse to the gas flow direction G, the second electrode 32, with its short L-shaped segment 35, at least segmentally surrounds the first electrode 31.

[0102] exist Figure 5c In, with Figure 5b Compared to the illustrated embodiment, the second electrode is designed as a heating circuit. However, as... Figure 5b As shown, the second electrode 32 has an L-shaped form.

[0103] exist Figure 5d The design shown in the image is consistent with that based on Figure 5c Compared to the previous implementation, this design has an additional segment 37 in the region of the second electrode 32. This additional segment 37 has the effect of the first electrode 31 being surrounded by the second electrode 32 to a greater extent, allowing for more uniform heating.

[0104] exist Figure 5e In this design, the first electrode 31 has a rectangular shape. In addition to the first outer electrode 32, a third electrode 38 is also formed. The second electrode 32 is U-shaped. The third electrode 38 encloses the second electrode 32 and is also U-shaped. The two outer electrodes 32 and 38 are not connected to each other and are each designed as a heating circuit.

[0105] according to Figure 5f In this implementation scheme, both the first electrode 31 and the second electrode 32 are designed in a U-shape. Both electrodes are designed as heating circuits.

[0106] exist Figure 5g In this configuration, the second electrode 32 is U-shaped. The second electrode 32 is also designed as a circulating heating circuit. The first electrode 31 has a meandering shape 51 and is also designed as a heating circuit. Due to the increased ohmic resistance, the first electrode 31 can also be used as a temperature sensor.

[0107] In Figure 5h, the second electrode 32 is designed as a U-shaped circulating heating loop. The first electrode 31 consists of a heating loop and an equipotential surface 50, which is at the same potential as the heating loop but is not connected as a heating surface.

[0108] The implementation scheme according to Figure 5i is based on Figure 5g This is a combination of the embodiment shown in Figure 5h. The second electrode 32 has a U-shaped form. The first electrode 31 is designed as a heating loop with a meandering shape 51 having a transverse equipotential surface 50. The meandering heating loop 51 may alternatively be referred to as a temperature sensor.

[0109] according to Figure 5jIn the illustrated embodiment, the second electrode 32 is again designed as a U-shaped circulating heating loop. However, the first electrode 31 has a meandering shape 51. The heating loop designed in this way can alternatively be called a temperature sensor.

[0110] In addition, two third electrodes 38 are formed. The third electrodes 38 are formed between the first electrode 31 and the second electrode 32 in the gas flow direction G. The third electrodes 38 can be connected to their own potential to optimize the adsorption effect on particles in the gas flow G.

[0111] Can be combined arbitrarily Figures 5a to 5j The implementation scheme shown is illustrated.

[0112] Figures 6a to 6d A top view (left side view) and side views A to A′ (right side view) of a possible embodiment of the resistive electrode structure 30 are shown, whereby the designs differ from each other in terms of the formation of the passivation layer 60.

[0113] in accordance with Figure 6a The design corresponds to the basis Figure 5f The design is as follows. No passivation layer is formed in the illustrated embodiment.

[0114] Figure 6b The electrodes 31 and 32 are mostly coated with a passivation layer 60. Only the sensor detection area 40, the third section 21 of the sensor 10, and the contact pads 70 and 70' of the two electrodes 31 and 32 are not coated with a passivation layer.

[0115] exist Figure 6c In the design shown, the top sides 71 and 71' of the first electrode 31 and the second electrode 32 are also provided with passivation layers in the sensor detection area 40. Only the end faces 72 and 72' of portions 33 and 34 of the first electrode 31 and the second electrode 32 do not have the passivation layer 60.

[0116] exist Figure 6d In the embodiment shown, in the sensor detection area 40, not only the end faces 72 and 72' of parts 33 and 34, but also the top sides 71 and 71' do not contain the passivation layer 60.

[0117] like Figure 6d As shown, the use of sensor 10, i.e., the design in which the top sides 71, 71′ and end faces 72, 72′ of electrode portions 33 and 34 are partially exposed, can improve the growth of granular filaments formed from the first electrode 31 toward the second electrode 32.

[0118] This sensor 10 can be manufactured by first applying a passivation layer 60 to the entire surface of the sensor detection area 40, and then removing it, for example, by laser ablation or photolithography etching.

[0119] The exposed portions of electrodes 31 and 32 also improve the discharge of charged particles that impact them.

[0120] Figures 7a to 7d illustrate an embodiment of sensor 10, which has a substrate 15 with a cylindrical shape.

[0121] In Figures 7a and 7b, the substrate 15 is designed as a full cylinder. Figures 7c and 7d show such embodiments of the substrate 15 having a hollow cylindrical shape.

[0122] In the gas flow direction G, on the surface 16 of the substrate 10, a first electrode 31 is formed in a first section 21, and a second electrode 32 is formed in a third section 23, as shown in FIG7a. A sensor detection area 40 is formed between the two electrodes 31 and 32. Electrodes 31 and 32 are located as circumferential electrodes on the surface 16 of the substrate 15. The two electrodes 31 and 32 are in contact, for example, by electrical leads, which are bonded to the surfaces of electrodes 31 and 32 by material bonding.

[0123] If the sensor 10 is placed in a tubular housing, the advantage of this embodiment is the symmetrical structure of the sensor 10. In measurement mode, the electric field is radially symmetrical, thus avoiding the accumulation of charged particles at the edges, as might occur in a substrate with a cubic shape. Furthermore, for the same substrate size, the sensor detection area 40 is increased. This thus improves the sensitivity of the sensor 10.

[0124] In Figure 7b, the first electrode 31 is not formed over the entire circumference. Instead, the first electrode 31 has a recess 41 such that a segment 42 of the second electrode 32 is guided toward the first front side 17 of the substrate 15. The segment 42 of the second electrode 32 serves as a lead for the second electrode 32. The first electrode 31 has a lead 42'.

[0125] This allows electrodes 31 and 32, along with their leads 42 and 42', to be fabricated together in a single step. This can be accomplished, for example, by means of roller screen printing. Alternatively, an insulating layer can be applied to a portion of the first electrode 31 to electrically decouple the leads 42 of the second electrode 32 from the first electrode 31 in the direction of the first front side 17 of the substrate 15.

[0126] The resistive electrode structure 30 in Figure 7c corresponds to the resistive electrode structure 30 of the embodiment shown in Figure 7a. The only difference is the hollow cylindrical design of the substrate 15. This hollow cylindrical design of the substrate 15 allows for variable possibilities regarding the contact of electrodes 31 and 32. For example, a through-hole can be formed through the substrate 15. Furthermore, the substrate 15 can be better connected to a housing (not shown). This connection can be made, for example, by inserting the substrate onto a mandrel.

[0127] According to the embodiment shown in FIG7d, the possibility that the inner side 14 of the substrate 15 can also be used as a sensor region is illustrated. The electrode structure on the surface 16 of the substrate 15 corresponds to the electrode structure 30 shown in FIG7b.

[0128] If the resistive electrode structure 30 is formed not only on the surface 16 of the substrate 15, but also on the inner side 14 of the substrate 15, the sensor detection range 40 increases by approximately two times. In the example shown, the inner side 14 of the substrate 15 serves as the second surface 19 of the substrate 15.

[0129] Figure 8a and Figure 8b The first electrode 31 and / or the second electrode 32 may have 40 peaks 65 or 66 in the sensor detection area 40.

[0130] exist Figure 8a In the embodiment shown, only the first electrode 31 in part 33 has peak 65.

[0131] according to Figure 8b In the illustrated embodiment, peaks 65 and 66 are formed in both electrode portions 33 and 34. Peaks 65 and 66 are designed to face each other. The tips 65 and 66 are designed to generate an enhanced electric field. This improves the sensitivity of sensor 10.

[0132] exist Figures 9b to 9g The diagram shows side views A to A′ of different implementation schemes, thereby relating to the formation of electrode portions 33 and 34 in the sensor detection region 40, according to... Figure 9a Perform this part at the location shown.

[0133] according to Figure 9b In the illustrated embodiment, portions 33 and 34 do not contain a passivation layer. End faces 72 and 72' extend substantially in a straight line.

[0134] exist Figure 9c In the sensor detection area 40, electrode portions 33 and 34 are constructed by etching in a manner that configures peaks 65 and 66 to enhance the electric field. End faces 72 and 72' are curved in the present case.

[0135] according to Figure 9d and Figure 9e The implementation plan corresponds to the one based on Figure 6c and Figure 6d The enlarged illustration shows that the passivation layer 60 can be applied to electrodes 31 and 32 such that, for example, only the end faces 72 and 72' are exposed, or both the end faces 72 and 72' and the top sides 71 and 71' are exposed.

[0136] Figure 9fA passivation strip 61 formed in the sensor detection area 40 is shown. The passivation strip 61 is spaced apart from both the first electrode 31 and the second electrode 32.

[0137] However, in Figure 9g The image shows a filler 62 composed of a passivation material. In this embodiment, the end faces 72 and 72' of electrodes 31 and 32 are only partially free of passivation material or passivation layer 60.

[0138] Figure 10 A possible embodiment of a sensor system 80 having a sensor 10 according to the present invention is shown.

[0139] Sensor 10 is disposed within housing 85. Sensor 10 is arranged such that a first front side 17 points toward the gas inflow opening 86 of housing 85, and a second front side 18 points toward the gas outflow opening 87 of housing 85. Housing 85 is conductive, and thus housing 85 is designed as an inner tube in the illustrated example.

[0140] The inner tube or housing 85 is arranged within the outer tube 81. The outer tube 81 has an inlet opening 82. In the example shown, the inlet opening 82 is slot-shaped and extends in the longitudinal direction of the outer tube 81.

[0141] In order to allow the sensor system 80 to be placed in, for example, an exhaust system, the sensor system 80 has a threaded connector 89. Alternative designs for the threaded connector 89 shown are also conceivable and possible.

[0142] The gas to be analyzed flows into the outer tube 81 through the inlet opening 82, and then the gas flow is guided 180 degrees into the housing 85, and then flows in layers through the sensor 10 in the direction of the gas outflow opening 87.

[0143] The gas outlet opening 87 is perpendicular to the gas flow G, and thus draws the analyzed gas away from the sensor 10. Additional applications of a temperature sensor and / or heater on the substrate 15 are also possible. In particular, integration of the two elements with either the first electrode 31 or the second electrode 32 is possible.

[0144] The features disclosed in the claims, specification, and drawings may be essential for various embodiments of the claimed invention, whether individually or in any combination of them.

[0145] Figure Labels

[0146] 1. Sensor System (Prior Art)

[0147] 2. Substrate (Prior Art)

[0148] 3. Resistive electrode structure (prior art)

[0149] 4. First comb-shaped electrode (prior art)

[0150] 5. Second comb-shaped electrode (prior art)

[0151] 6. Sensors (Prior Technology)

[0152] 7. Housing (Prior Art)

[0153] 10 sensors

[0154] 14. Inner side

[0155] 15 Substrates

[0156] 16 First Surface

[0157] 17 First Anterior Side

[0158] 18 Second Anterior Side

[0159] 19 Second Surface

[0160] 21 First Section

[0161] 22 Second Section

[0162] 23 Third Section

[0163] 24 Edge Section

[0164] 30 Resistive electrode structure

[0165] 31 First Electrode

[0166] 32 Second electrode

[0167] 33 Part of the first electrode

[0168] 34. The second electrode portion

[0169] 35 Short Section

[0170] 36 long sections

[0171] 37 Additional Section

[0172] 38 Third electrode

[0173] 40 Sensor detection area

[0174] 41 recess

[0175] 42 Local area of ​​the second electrode

[0176] 42′ Lead of the first electrode

[0177] 50 Equipotential Region

[0178] 51. Winding section

[0179] 60 passivation layer

[0180] 61 Passivation strip

[0181] 62 Filler

[0182] 65 Peak of the first electrode

[0183] 66 Peak of the second electrode

[0184] 70, 70′ contact pads

[0185] 71, 71′ Top side

[0186] 72, 72' end faces

[0187] 80 Sensor Systems

[0188] 81 outer tube

[0189] 82 Entrance opening

[0190] 85 Housing

[0191] 86 Gas inflow opening

[0192] 87 Gas outflow opening

[0193] 89 Threaded fasteners

[0194] 91 First Electric Field

[0195] 92 Second Electric Field

[0196] G Gas flow direction

Claims

1. A sensor (10) for detecting charged particles in a gas stream, the sensor comprising a substrate (15) having a cubic or cylindrical shape having two front sides (17, 18). The gas flow direction (G) is defined as extending in a direction from the first front side (17) of the substrate (15) to the second front side (18) of the substrate (15). A resistive electrode structure (30) comprising at least two electrodes (31, 32) is formed on at least one surface (16, 19) of the substrate (15). The at least two electrodes (31, 32) are electrically separated from each other. Its features are, A first electrode (31) is arranged in a first section (21) of the sensor (10) relative to the gas flow direction (G) and is designed such that the first electrode (31) acts as an adsorption electrode, wherein the adsorption electrode is switchable to attract charged particles. A sensor detection region (40) is formed in the second segment (22) of the sensor (10), wherein the sensor detection region (40) is formed by a portion (33) of the first electrode (31) and a portion (34) of the second electrode (32) spaced apart from the portion (33) of the first electrode (31). The second electrode (32) is at least partially formed in the third segment (23) of the sensor (10), wherein Considering the gas flow, the adsorption electrode is placed in front of the sensor detection area (40), and The attraction potential of the adsorption electrode forces the charged particles carried in the gas flow toward the adsorption electrode. The volatile particles on or above the adsorption electrode are removed by the gas flow toward the sensor detection area (40), and this causes a resistance change between the first electrode (31) and the second electrode (32), wherein the second electrode (32) is made into a heating element and the resistive electrode structure (30) does not have an interdigitated capacitor structure (IDC), and wherein the sensor (10) has only a single sensor detection area (40), and The gap between the first electrode (31) and the second electrode (32) in the sensor detection area (40) is substantially perpendicular to the gas flow direction and is oriented as a slit, wherein the width of the gap is at most 70µm and at least 20µm. The area ASE covered by the adsorption electrode is greater than the area ADR between the first electrode and the second electrode in the sensor detection area, and the ratio of ASE to ADR is at least 50.

2. The sensor (10) according to claim 1. Its features are, The first electrode (31) and / or the second electrode (32) are segmentally coated with a passivation layer (60), thereby at least partially free of the passivation layer (60) in the sensor detection area (40).

3. The sensor (10) according to claim 1. Its features are, The second electrode (32) has a rectangular shape, a U-shaped shape, or an L-shaped shape.

4. The sensor (10) according to claim 1. Its features are, The first electrode (31) has a rectangular or U-shaped shape.

5. The sensor (10) according to claim 1, Its features are, At least one third electrode (38) is formed between the first electrode (31) and the second electrode (32) or is formed to at least partially surround the second electrode (32).

6. The sensor (10) according to claim 1. Its features are, The first electrode (31) has a longitudinal extension from 0.5 mm to 100 mm. And / or Width range from 0.5mm to 50mm The longitudinal extension extends in the gas flow direction (G) and the width extension extends perpendicular to the gas flow direction (G).

7. A sensor system (80) comprising a sensor (10) according to any one of claims 1 to 6. Thus, the sensor (10) is arranged in a conductive housing (85) having a gas inlet opening (86) and a gas outlet opening (87), wherein the first front side (17) of the substrate (15) is arranged facing the gas inlet opening (86), and the second front side (18) of the substrate (15) is arranged facing the gas outlet opening (87).

8. The sensor system (80) according to claim 7. Its features are, During the measurement mode of the sensor system (80), a first electric field (91) is formed between the first electrode (31) and the conductive housing (85), the first electric field being unidirectional, and a second electric field (92) is formed between the first electrode (31) and the second electrode (32).

9. The sensor system (80) according to claim 7. Its features are, The conductive housing (85) is designed as an inner tube, which is arranged in the outer tube (81).

10. The sensor system (80) according to claim 9. Its features are, The outer tube (81) has an inlet opening (82) formed in the side surface of the outer tube (81) in the longitudinal direction.

11. Use of the sensor (10) and / or sensor system (80) according to any one of the preceding claims for detecting carbon soot particles in the exhaust system of a vehicle.

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