WO2021005074A1

WO2021005074A1 - Impedance spectroscopy sensor with a sealing varnish cover layer

Info

Publication number: WO2021005074A1
Application number: PCT/EP2020/069152
Authority: WO
Inventors: Dirk SCHÖNFUSS
Original assignee: Hamilton Bonaduz Ag
Priority date: 2019-07-09
Filing date: 2020-07-07
Publication date: 2021-01-14
Also published as: EP3997450A1; DE102019118529A1

Abstract

The invention relates to an impedance spectroscopy sensor (10), comprising: a carrier plate (12) having a media side (14) facing a medium during the measuring operation and having a connection side (16) opposite the media side (14) for electrically conductively connecting a control and/or evaluation electronics system (39); through-openings (72-82) which run between the media side (14) and the connection side (14), penetrating the carrier plate (12); a plurality of electrically conductive sensor surfaces (46-56) on the media side (14), which are at least partially exposed; and a plurality of electrical contact surfaces (22-36, 40, 42) on the connection side (16), which are at least partially exposed on the connection side (16); wherein at least one portion of the electrical contact surfaces (22-36, 40, 42) are electrically conductively connected to the sensor surfaces (46-56) on the media side (14) via the through-openings (72-82). According to the invention, a media cover layer (70) is applied at least to the media side (14), which has recesses (58-68) in the extension region of the sensor surfaces (46-56) penetrating the media cover layer (70) in the thickness direction, and which covers at least one portion of the through-openings (72-82) and a respective conductor path section coming from a through-opening (72-82).

Description

Impedance spectroscopy sensor with a sealing glaze top layer

description

The present invention relates to an impedance spectroscopic sensor for impedance spectroscopic examination of a liquid or pasty medium, in particular a suspension, particularly preferably a cell suspension. The sensor includes:

a carrier plate with a media side facing the medium during measurement operation and with a connection side opposite the media side for the electrically conductive connection of a control and / or evaluation electronics,

Through openings which, penetrating the carrier plate, run between the media side and the connection side,

on the media side: a plurality of electrically conductive sensor surfaces which are exposed at least in sections for contacting through the medium, and

On the connection side: a plurality of electrical contact surfaces, wel che on the connection side for contacting by at least one further electrical line are exposed at least in sections, at least some of the electrical contact surfaces being electrically conductively connected through the through openings through to the sensor surfaces on the media side .

An impedance spectroscopy sensor of the generic type is known from WO 2006/107728 A1. There, as elsewhere in the prior art, the impedance spectroscopy sensor is referred to as a "conductivity sensor". WO 2006/107728 A1 teaches forming through openings on a ceramic carrier plate using etching technology and filling them with electrically conductive material. Through openings that are incompletely filled with electrically conductive material can be filled with sintered glass for sealing. WO 2006/107728 A1 further teaches, both on the media side and on the connection side by means of evaporation and deposition processes taken from semiconductor processing, such as physical vacuum evaporation (PVD), chemical vapor deposition (CVD), electrochemical deposition (ECD) etc. on each each filled through-opening to arrange an electrode covering the filled through-opening. The media-side electrode, made of platinum or gold, for example, is used to contact the liquid medium to be examined. The electrode on the connection side is used to connect electrical lines to it for signal transmission to signal analysis devices arranged remotely from the sensor. The respective electrodes of the sensor known from WO 2006/107728 A1 are each completely exposed on the side on which they are arranged.

The disadvantage of this sensor is that even on the through openings that are completely filled with electrically conductive material and possibly with additional filling material, their tightness against migration of low-viscosity media components from the media side to the connection side - or against migration of atmospheric components in the opposite direction - cannot be guaranteed. This can primarily affect long-term and / or repeated sensor use.

To classify the sensor of the present invention and its preferred area of application, the following briefly introduces the basics of impedance spectroscopy and impedance spectroscopy sensors: electrical impedance spectroscopy methods are used as a measurement method for the non-destructive in-situ and in-vivo determination of frequency-dependent passive electrical properties of biological Materials used. Such a biological material can, for example, be a substance, hereinafter referred to as “biomass” or “medium”, composed of a liquid and biological cells contained therein, such as is obtained from cell culture containers.

The above-mentioned frequency-dependent passive electrical properties of biomass can provide information about the number of living cells and cell vitality, among other things give. In addition, other properties of the biomass can be determined by the frequency-dependent passive electrical properties, but the determination of the number of living cells and cell vitality is of greatest importance in biotechnological applications.

Basically and roughly sketched, the impedance spectroscopic recording of information about the quantity and / or size of living cells in the biomass is carried out as follows: a suspension of biological cells absorbed in a carrier liquid is connected to the electrically conductive sensor surfaces on the media side of the sensor applied electric field whose field direction changes periodically with a predetermined frequency. Depending on the selected frequency of change, different polarization mechanisms act on the biomass. Therefore, the passive electrical properties of biomass, in contrast to purely ionic solutions, are frequency-dependent and form typical so-called dispersions. If there are living cells in the biomass, additional effects arise. The living cells represent a migration barrier for freely moving ions, so that the cells increase the electrical resistance of the biomass depending on their cross-sectional area and consequently reduce its conductivity. The ions present inside a cell of the biomass are also detected by the electrical field. Charge separation occurs on the poorly electrically conductive cell membrane, which leads to polarization on the membrane. The polarization occurs as an electrical double layer. In this case, the current caused by the electrical field flows almost exclusively through the extracellular carrier substance of the biomass. The polarization is therefore reflected in the increase in the measurable capacitance and consequently in the permittivity between the field-generating electrodes.

A so-called "a-dispersion" occurs in the millihertz to kilohertz frequency range and is caused by the movement and accumulation of charge carriers on the cell surface. Active cell membrane effects and active ionic membrane channels also influence α-dispersion. In a frequency range from a few kilohertz to one hundred megahertz, what is known as ß-dispersion occurs, which is based on the capacitive properties of the cell membranes, the intracellular organelles and the membrane structures themselves. The fats and proteins in the cell membranes form a high-resistance structure. The membrane structures lead to so-called interface polarization.

At even higher frequencies in the range from approx. 0.1 to 100 GHz, so-called g-dispersion occurs, which is caused by dipolar mechanisms in polar media, such as water and proteins. In the electric field, large molecules, such as B. Proteins, with dipole moment.

For the sensor of the present application particularly interesting acquisition of information about the amount and / or size of living cells in a biomass is primarily the ß-dispersion area of interest, which is also detected by electrically conductive sensor surfaces on the media side. For further information about the dispersion areas of biomass and the curves of a frequency-dependent permittivity or capacity used for their representation, reference is made to HP Schwan: "The practical success of impedance techniques from an historical perspective", in: Proceedings of the X. International Conference on Electrical Bio-Impedance, Barcelona (1998), pages 3 to 16, and also on HP Schwan: "Electrical properties of tissue and cell suspensions", in: Advances in Biological and Medical Physics, Vol. 5 (1957), pages 147 to 205.

A known method for the impedance spectroscopic detection of information about the quantity and / or size of living cells in a biomass by means of an electric field with a periodically changing field direction is known from US Pat. No. 7,930,110 B2. A usable for such a measurement Impedanzspektro skopie sensor is known from US 6 596 507 B2. A sensor sold by the present applicant under the trade name “Incyte” is also an impedance spectroscopy sensor. It is the object of the present invention to improve the aforementioned Impedanzspek troscopy sensor, or in the following only briefly "sensor", in terms of its ability between the media side and the connection side, especially in the area of the through openings.

This object is achieved according to the invention by a sensor of the type mentioned at the outset, in which it is additionally provided that a media cover layer is applied at least on the media side, which has recesses penetrating the media cover layer in the direction of thickness in the extension area of the sensor surfaces and which at least covers part of the through-openings and in each case a conductor track section starting from a through-opening.

The media cover layer, which preferably covers at least 70% of the media-side surface of the carrier plate, an additional layer that increases the tightness of the carrier plate is applied to the media side of the carrier plate. The sensor surfaces lie in a thickness direction of the sensor that coincides with the direction of the distance between the media side and the connection side between the media cover layer and the carrier plate. Due to the recesses described, the sensor surfaces are accessible from the outside despite the formation of the media cover layer and can thus fulfill their intended detection task.

For easier handling, in particular printing on the carrier plate, the carrier plate is preferably flat on at least one side, preferably on both sides.

Because the media cover layer covers at least part of the through openings, the covered through openings are not directly accessible from the medium to be detected, which wets the media side of the sensor during a designated detection mode. The conductor track section, which is also covered by the media cover layer, can be made of the same material as the sensor surface, which is covered with electrically conductive material in the covered passage opening connects. Because the media cover layer also covers a conductor track section extending from the covered through opening, it is possible to arrange the sensor surface, which is defined by the recess in the media cover layer and assigned to the covered through opening by electrically conductive connection, away from the through opening. so that a possibly existing creepage path for low-viscosity parts of the medium to be detected in a possibly existing gap between media cover layer on the one hand and carrier plate and / or sensor surface and / or conductor track section on the other hand can be long. The probability that liquid, starting from the recess on the sensor surface, passes through a gap, if at all, then at most with a very small gap thickness in the single-digit μm range, to the passage opening and further through this to the connection side is negligibly low.

The media cover layer preferably covers all through openings on the media side.

To connect the sensor surfaces on the media side with one passage opening each, a plurality of media-side electrical conductor tracks can be formed on the media side, each of which electrically conductively connects a passage opening with at least one sensor surface. The media cover layer then preferably covers a plurality of conductor track sections, each covered conductor track section preferably extending from a different through opening to a sensor surface.

This also makes it possible to arrange and align the sensor surfaces on the media side of the carrier plate as required and suitability with an excellent barrier effect of the sensor against the passage of liquid from the media side to the connection side.

In order to connect the contact surfaces to the sensor surfaces on the connection side of the carrier plate on the one hand in an electrically conductive manner and on the other hand to arrange them freely and to be able to align, a plurality of electrical conductor tracks on the connection side can also be formed on the connection side, each of which electrically conductively connects a through opening with at least one contact surface. Since electrical conductor paths lead from the through opening to the sensor surfaces on the media side and electrical conductor paths lead from the through opening to the contact surfaces on the connection side, the sensor surfaces are electrically connected to the contact surfaces in the desired manner.

The sensor surfaces are preferably made of chemically very resistant, electrically conductive metal, since they are in direct wetting contact with the medium to be detected. If the recesses in the media cover layer that provide access to the sensor surfaces are advantageously chosen so that a media-side electrical conductor track, which connects the sensor surface to a passage opening, is no longer wetted by the medium to be detected, the media-side electrical conductor track can then be removed be formed from a different material, in particular special from a cheaper material than the sensor surface. All that is required is an electrically conductive connection between the electrical conductor track and the sensor surface assigned to it. This preferably applies to all sensor surfaces and their associated media-side electrical conductors. For example, to form a sensor area, an area on the media side of the carrier plate covered with sensor area material can be larger than the area of the recess assigned to the sensor area. Then, on the finished sensor that is ready for operation, the area of a recess assigned to a sensor area is completely filled by the sensor area.

Since the connection-side electrical conductor tracks and contact surfaces are not wetted by the medium to be detected anyway, the connection-side conductor tracks can alternatively or additionally also be made of a different material than the sensor surfaces on the media side. The media-side and / or connection-side electrical conductor tracks are preferred to avoid unnecessarily high costs made of a material with a lower positive normal potential in terms of amount compared to a normal hydrogen electrode, measured at 25 ° C., 1013 hPa. The sensor surfaces particularly preferably comprise platinum or preferably gold. A PtAg alloy has proven to be particularly effective. The media-side and / or connection-side electrical conductor tracks preferably comprise silver or a silver alloy. An AgPd alloy is particularly preferred. Despite all the differences between the materials mentioned, the material for producing the sensor surfaces and the material for producing the electrical conductor tracks preferably have a common electrically conductive alloy component in order to avoid undesirable galvanic corrosion at contact points of the different materials.

In contrast to the sensor surfaces, which only have to be wettable and should be chemically stable, it is advantageous for easier connection of electrical conductors to the contact surfaces if the material of the contact surfaces allows a soldered connection, i.e. is solderable. The AgPd alloy mentioned above does this.

In order to ensure a continuous electrical conductivity that is particularly easy to produce and to avoid unnecessary galvanic elements, the media-side electrical conductor tracks and the connection-side electrical conductor tracks are preferably formed from the same material.

For the same reason, contact surfaces and the connection-side Lei terbahnen are preferably formed from the same material. They are preferably formed in one piece.

In order to make moisture or liquid access to the passage openings more difficult on the connection side as well, a connection cover layer can also be applied to the connection side, which has recesses penetrating the connection cover layer in the direction of thickness in the extension area of contact surfaces and which has at least part of the Covered through openings. The connection cover layer preferably additionally covers at least part of the connection-side conductor tracks for the reasons already mentioned above for the media cover layer. What has been said above and below about the media cover layer applies to the connection cover layer. For even better shielding of electrically conductive components of the sensor, the media cover layer preferably covers at least a part, preferably all of the media-side conductor tracks completely. According to this advantageous development, only material from the sensor surfaces is located on the media side of the carrier plate in the area of the associated recesses in the media cover layer. To produce an electrically conductive connection, material of a media-side electrical conductor track can also be found in the area of such a recess, but then preferably under the material of the sensor surface, i.e. in the thickness direction of the sensor between the sensor surface and the carrier plate. Such an overlap of the material of a sensor surface and the material of an electrical conductor path is, however, preferably formed under the media cover layer.

Particularly advantageously, at least some of the through openings, preferably all through openings, can have material from the connection-side and / or the media-side electrical conductor tracks in order to provide an electrically conductive connection between the media side and the connection side through the respective through-opening. Thus, material of the connection-side and / or the media-side electrical conductor tracks can be located in at least some of the through openings in order to form a section of the electrically conductive connection of contact surfaces on the connection side with sensor surfaces on the media side.

In order to avoid unwanted galvanic elements in the through-openings and to be able to ensure good electrical conductivity through the through-openings, only material from the connection-side and / or media-side electrical conductor tracks is preferably located in at least some of the through-openings. The filling of the through-openings with the material of the connection-side and / or the media-side electrical conductor tracks can be made in a simple manner together with the electrical conductor tracks ago. The electrical conductor tracks - as well as the rest of the sensor surfaces - are preferably produced using the screen printing process, which is compared to Application method of WO 2006/107728 A1, which is borrowed from semiconductor technology, means a considerable procedural simplification of the manufacturing method. After the electrical conductor tracks have been applied to the carrier plate, the carrier plate is preferably thermally fired in order to transfer the conductor tracks to their final status and to fix them on the carrier plate. The same also applies to the sensor surfaces after they have been applied to the carrier plate and, if necessary, in sections over a section of the, then preferably already fired, Lei terbahnen.

Most or even all of the contact surfaces on the connection side can be connected to a plug or socket element, which enables the sensor to be connected to a signal evaluation device and / or to a signal feed device in a simple manner. An electrical conductor then runs from the signal evaluation device and / or signal feed device with a device-side socket or plug element complementary to the plug or socket element of the sensor, so that a simple electrically conductive connector between the sensor and the signal evaluation device and / or signal feed device can be established. Of course, according to an embodiment which is less preferred because of the reduced flexibility of the possible uses of the sensor, electrical lines coming from the signal evaluation device and / or signal feed device can also be soldered or otherwise connected directly to the contact surfaces. At least two of the contact surfaces can be connected to a temperature sensor in order to be able to additionally provide temperature information about the sensor during operation. In this way, the detection results supplied by the sensor can be temperature-compensated online.

The media cover layer preferably covers 70% or more, for example at least 85%, of the media-side surface of the carrier plate. An outer circumference of the media cover layer preferably encloses more than 90% or even more than 95% of the media-side surface of the carrier plate. In a later further processing, the sensor, including the carrier plate, the sensor surfaces, the electrical conductor tracks and contact surfaces as well as the media cover layer and optionally the connection cover layer can be embedded in a plastic housing, preferably by molding the plastic housing onto the sensor in an injection molding process. A particularly durable and resilient connection between the plastic housing and the sensor can be obtained by arranging the edge of the carrier plate on the media side parallel to the media-side surface of the carrier plate at a distance from an edge of the media cover layer that runs around the media cover layer is.

The carrier plate is preferably made of an electrically non-conductive ceramic material compared to the materials used to manufacture the sensor surfaces, the contact surfaces and the said electrical conductors. The carrier plate is preferably made only from this non-conductive ceramic. The ceramic can have a rougher surface that is particularly suitable for connection to the injection-molded plastic than the media cover layer and / or the connection cover layer. The carrier plate is preferably made from a sintered ceramic so that the media cover layer and / or the connection cover layer can enter into a micro-positive, high-strength connection with the carrier plate. The same applies to any plastic that has been injected.

All materials for producing the carrier plate, cover layers, sensor surfaces, contact surfaces and electrical conductor tracks are preferably free of cadmium.

To ensure the best possible connectivity with plastic on the connection side of the sensor, it is advantageous if the edge of the carrier plate on the connection side is arranged parallel to the connection-side surface of the carrier plate at a distance from an edge of the connection cover layer that runs around the connection cover layer is. The distance between the respective cover layer and the edge of the carrier plate along the edge of the carrier plate is preferably constant both on the media side and on the connection side. The media and / or connection cover layer can also be a ceramic layer which must not be electrically conductive in order not to make short circuits between the sensor surfaces or the conductor tracks or the contact surfaces. The cover layer is preferably a glass-like layer, such as a glaze or a sheet of glass. The media and / or connection cover layer can first be applied very precisely using the screen printing process and then thermally brought into an amorphous state of high density by firing or firing.

The present invention also relates to a method for producing a sensor, as described and developed above. The procedure comprises the following procedural steps:

Provision of a carrier plate with the media side facing the medium during measurement operation and with the connection side opposite the media side as well as with through-openings which, passing through the carrier plate, run between the media side and the connection side,

Printing the connection side with a first print medium containing electrically conductive particles to form the contact surfaces,

Printing the media side with a second printing medium containing electrically conductive particles to form the sensor surfaces,

Application of a media cover layer on the printed media side, leaving out sensor surface areas,

wherein when printing the connection side and / or when printing the media side, through openings are filled with the first and / or with the second printing medium.

The method has already been explained in detail above in connection with the description of the sensor, so that reference is made to the above lecture on the sensor for a more detailed explanation of the method. Accordingly, the preferred printing method is a screen printing method, although other printing methods should not be excluded. The advantages and configurations of the sensor resulting from the method mentioned are further developments of the inventive sensor sors. Advantages and configurations of the manufacturing method of the sensor resulting from the described sensor are further developments of the manufacturing method according to the invention.

Since the media-side electrical conductor tracks are preferably to be arranged at least in sections between the sensor surfaces and the carrier plate, it is preferred if the method has a step of printing the media side with the first printing medium before printing the media side with the second printing medium form the media side electrical traces trainees.

Between two steps of printing one and the same side of the carrier plate with different print media, the method preferably includes the step of burning the print medium that has already been printed on, with the print medium that has already been printed on being melted and / or its constituents being evaporated.

To avoid undesirable material mixtures in the Durchgangsöffnun conditions and / or to provide a maximum of electrically conductive material filled through openings, it is advantageous if when printing the connection side and / and when printing the media side, through openings are only filled with the first print medium.

As already explained in connection with the sensor, the method can have the step of applying a connection cover layer to the printed connection side while leaving out contact surface areas. A cover layer, be it the media or the connection cover layer, is preferably applied using the screen printing process. Since glass-like cover layers are preferred, a cover layer is not applied in the final form used on the finished sensor, but as an intermediate product, which is subjected to a thermal melt treatment after application. To implement this melt treatment, the method can use at least one

Step of burning the provided with at least one material application, in particular special printed and / or provided with at least one cover layer, carrier plate.

Fig. 1: a schematic elevation view of an inventive embodiment of an impedance spectroscopy sensor of the present application,

FIG. 2A: a schematic plan view of the connection side of the sensor from FIG. 1,

2B: a schematic top view of the media side of the sensor from FIGS. 1 and 2A,

3A: a schematic plan view of the media side of the carrier plate of the sensor of FIGS. 1 and 2, only the electrical conductor tracks printed thereon being shown,

3B: a schematic plan view of the media side of the carrier plate of the sensor of FIGS. 1 and 2, only the material printed thereon for forming the sensor surfaces being shown,

3C: a schematic plan view of the media side of the carrier plate of the sensor of FIGS. 1 and 2, only the media cover layer applied thereon being shown,

4A: a schematic plan view of the connection side of the carrier plate of the sensor of FIGS. 1 and 2, only the electrical conductor paths printed thereon being shown, and

4B: a schematic plan view of the connection side of the carrier plate of the sensor in FIGS. 1 and 2, only the connection cover layer applied thereon being shown. In Figure 1, an embodiment according to the invention of an impedance spectroscopy pie sensor of the present application is generally designated 10. The sensor 10 comprises a carrier plate 12, preferably made of sintered ceramic, with a media side 14 facing a medium M as the measurement object, such as a cell suspension, when the sensor is in detection mode, and an opposite connection side 16 that faces away from the medium and is used for electrical connections.

On the media side 14 there are a total of three flat orders in sample form made from different materials. These are explained in more detail below in connection with FIGS. 3A to 3C.

On the connection side 16 there are a total of two flat orders in the form of samples made of different materials. These are explained in more detail below in connection with FIGS. 4A and 4B.

On the connection side 16 there is a plug element 18 which, with its total of eight contact feet 20, is soldered to eight contact surfaces 22 to 36 (see FIG. 4A). On its side facing away from the contact feet 20, the plug element 18 comprises eight connection pins 38, each of which is electrically conductively connected to a different contact foot and which, by plugging in a corresponding socket element (not shown in the figures) with a signal evaluation device and / or signal feed device 39, for signal transmission can be electrically connected.

On the connection side, a temperature sensor 44 is soldered to two further contact surfaces 40 and 42, through which signals generated by the temperature sensor 44, which transport temperature information about the sensor 10 in the area of the carrier plate 12, to the contact surfaces 34 and 26 and thus to be assigned At the connection pins of the connector element 18 are transmitted. In Figure 2A, the connection side 16 of the sensor 10 is shown in plan view. For the sake of clarity, not all eight connection pins of the connector element 18 are provided with reference symbols.

In Figure 2B, a plan view of the media side 14 of the sensor 10 and the carrier plate 12 is shown. In this application, the page references: media side and connection side are used both for the sensor as a whole and for the carrier plate, since the flat carrier plate is decisive for the mentioned sides and separates the connection side from the media side.

The sensor areas 46 to 56 can be seen in FIG. 2B, each of which is accessible through a recess 58 to 68 in a glass-like media cover layer 70.

The carrier plate 12 has a hexagonal base, but this is only an example. The base of the carrier plate 12 can have any shape, such as circular, elliptical, square, octagonal and the like. The carrier plate 12 is preferably flat.

Since the edge 70a of the media cover layer 70 extends from the side edge 12a of the carrier plate 12 at a, preferably constant, distance in the direction of the center of the carrier plate 12, the media cover layer 70 also has a hexagonal basic shape.

In the example shown, the areas of the cutouts 58 to 68 are each larger than the areas of the sensor areas 46 to 56 which are accessible through the cutouts 58 to 68 for the medium as the measurement object. This need not be the case. The sensor areas 46 to 56 can also be designed with a larger area than the recess assigned to them, so that a recess assigned to a sensor area with its recess area determines the size of the sensor area. In Figure 3A, the media side 14 of the carrier plate 12 is shown. Six through-openings 72 to 82 can be seen, which are designed as the carrier plate 12 in a thickness direction that is orthogonal to the plane of the drawing in FIG. 3A and thus enable a physical connection between the media side 14 and the connection side 16.

In the area of the through openings 72 to 82, electrical conductor tracks 84 to 94 are printed on the media side 14 using the screen printing process, namely in the illustrated embodiment in the area of each of the through openings 72 to 82 each an electrical conductor track 84 to 94. With the imprint of the conductor tracks 84 conductor track material was also introduced into the through openings 72 to 82 in order to form an electrical line passing through the through openings 72 to 82. The electrical conductor tracks 84 to 94 are printed on as a paste which contains a silver-palladium alloy. The electrical conductor tracks 84 to 94 are fixed on the carrier plate 12 by firing. For this purpose, the printed carrier plate is heated to temperatures of over 800 ° C. In the completely fired state, the electrical conductor tracks 84 to 94 can be soldered. Although it should not be ruled out that only one firing process thermally fixes all melt-treatable material applications applied to the carrier plate at the same time, in order to achieve the most exact possible material application image on the carrier plate 12, it is preferred if the carrier plate is fired several times. Preferably, the carrier plate 12 is fired material by material, so that after each application, in particular special imprint, of a material and before an application, in particular imprint, of another material on the same side of the carrier plate, the material already applied in a pattern is fixed by firing. Likewise, after the last material application, which is usually a top layer, the applied material is fixed by firing.

The conductor tracks 84 to 94 each have an overlap section which is identified by the same reference symbol as the conductor track, but with the addition of the lowercase letter "a". The overlapping sections 84a to 94a, some or all of which have a larger area than they are associated with The remaining conductor track connecting the through-opening can be formed, preferably after a firing process, overprinted with material for the production of the sensor surfaces 46 to 56, so that the overlapping sections 84a to 94a at the end of the production process between the material of the sensor surfaces 46 to 56 and the carrier plate 12 is located.

Preferably after the conductor tracks 84 to 94, the sensor surfaces 46 to 56 are printed onto the media side 14 of the carrier plate 12, likewise using the screen printing process, and onto the overlapping sections 84a to 94a. These are shown in Figure 3B. The sensor areas 46 to 56 each have an overlap section labeled with the same reference as the rest of the sensor area, but with the addition of the lowercase letter "a", which terbahnen an associated one of the overlap sections 84a to 94a of the Lei in the above-mentioned manner 84 to 94 to produce an electrically conductive connection with the sen overlaps. If FIG. 3B were to be printed out on a transparent base and placed over FIG. 3A, the continuous electrical line from the through openings 72 to 82 to the sensor surfaces 46 to 56 would be seen. The screen-printable paste used to produce the sensor surfaces 46 to 56 contains platinum, in particular a platinum-silver alloy. These pastes are also fired, preferably in a separate firing process before the media cover layer is applied.

The media cover layer shown in FIG. 3C is then applied to the media side printed with the media-side electrical conductor tracks 84 to 94 and the sensor surfaces 46 to 56. The raw material of the media cover layer is also applied using the screen printing process. After the media cover layer, which is preferably printed on, has been fired, the media cover layer forms a vitreous layer, such as a glaze layer or glass layer. The recesses 58 to 68 are already produced during the application, in the area of which there is no material of the media cover layer, so that the recesses 58 to 68 completely penetrate the media cover layer in the direction of the thickness and so that the cut-out Rungs 58 to 68 through the sensor surfaces 46 to 56 are accessible and in particular wettable by the medium as the measurement object.

The media cover layer covers each of the passage openings 72 to 82 and sections of the media-side electrical conductor tracks 84 to 94 emanating from them in order to seal the passage openings 72 to 82 against the passage of a large, low-viscosity component of the medium as a measurement object from the media side 14 to the connection side 16 For example, in the exemplary embodiment shown, each through opening is surrounded by conductor track material. At least the conductor track sections surrounding sen covers the media cover layer 70.

The media cover layer 70 with its edge 70a does not extend as far as the edge 12a of the carrier plate 12, but ends at a small distance therefrom in order to facilitate the injection molding of the carrier plate 12 with plastic.

In Figure 4A, the connection side of the carrier plate 12 is shown as it is after a screen printing of contact surfaces 22 to 36, 40 and 42 and integrally formed with the contact surfaces 22 to 36, 40 and 42 connection-side electrical conductor tracks 96 to 108, which Connect contact surfaces with through openings 72 to 82 and with one another, looks. The connection-side electrical conductor tracks 96 to 104 each connect a through-opening to at least one contact surface, the branched connection-side conductor track 98 also creating an electrically conductive connection between the through-openings 74 and 80. The connection-side electrical conductor tracks 106 and 108 connect the connection contact surfaces 40 and 42 of the temperature sensor 44 with associated connection contact surfaces 34 and 26 for the connection of the plug element 18 to it, as already described above.

To form the contact surfaces 22 to 36, 40 and 42 and the connection-side conductor tracks 96 to 108, the same material is used as for the production of the media-side electrical conductor tracks 84 to 94. With the application of conductive paste to the connection side 16, the connection side 16 is also used Ladder- Web material is brought into the through openings 72 to 82, so that an electrically conductive connection extending from the media side 14 to the connection side 16 is secured in the thickness direction through the carrier plate 12. However, since the volume of the conductor track material can decrease when it is fired, the tightness of the through openings 72 to 82 is not fundamentally secured after firing. The seal is produced by the media cover layer 70. To improve the tightness of the passage openings 72 to 82 against the passage of liquid through them, a connection cover layer 130 can also be applied to the connection side 16. It is preferably formed from the same material and applied and processed in the same method as the media cover layer 70, so that the statements made above about media cover layer 70 apply to the connection cover layer 130. The connection cover layer 130 can be fired in a joint firing process with the media cover layer 70.

The media-side and the connection-side conductor tracks can also be burned in a common burning process.

Through recesses 110 to 128, which in turn completely penetrate the connection cover layer 130 in the thickness direction, the contact surfaces 22 to 36, 40 and 42 are for contact with electrical conductors, sensor components, such as the temperature sensor 44, or connecting components, such as the plug element 18, accessible to produce an electrically conductive connection with the contact surfaces.

The connection cover layer 130 covers all through openings 72 to 82 and a conductor track area surrounding the through openings 72 to 82, so that an exchange of liquid between the media side 14 and the connection side 16 within the usual operating phases of the illustrated impedance spectroscopy sensor 10 is virtually impossible.

The edge 130a of the connection cover layer 130 also runs at a small distance from the edge 12a of the carrier plate 12 so that plastic molded around the carrier plate 12 can encompass the carrier plate 12 from three sides and on these three sides can enter into a high-strength mechanical cal connection with the merely sintered surface of the carrier plate 12.

Claims

Expectations

1. Impedance spectroscopy sensor (10) for impedance spectroscopic investigation of a liquid or pasty medium, in particular a suspension, the sensor comprising:

a carrier plate (12) with a media side (14) facing the medium (M) during measurement operation and with a connection side (16) opposite the media side (14) for the electrically conductive connection of control and / or evaluation electronics (39),

Through-openings (72-82) which, through the carrier plate (12), run between the media side (14) and the connection side (14),

on the media side (14): a plurality of electrically conductive sensor surfaces (46-56) which are exposed at least in sections for contacting through the medium (M), and

on the connection side (16): a plurality of electrical contact surfaces (22-36, 40, 42) which are exposed at least in sections on the connection side (16) for contacting through at least one further electrical line (20), with at least a part the electrical contact surfaces (22-36, 40, 42) are electrically conductively connected to the sensor surfaces (46-56) on the media side (14) through the through openings (72-82),

characterized in that at least on the media side (14) a media cover layer (70) is applied, which in the area of extent of the sensor surfaces (46-56) has the media cover layer (70) in the direction of thickness through recesses (58-68) and which covers at least part of the through openings (72-82) and in each case a conductor track section extending from a through opening (72-82).

2. Sensor (10) according to claim 1,

characterized in that a plurality of media-side electrical conductor tracks (84-94) are formed on the media side (14), each of which because a through opening (72-82) is electrically connected to at least one sensor surface (46-56).

3. Sensor (10) according to claim 1 or 2,

characterized in that a plurality of connection-side electrical conductor tracks (98-104) are formed on the connection side (16), each of which electrically conductively connects a through opening (72-82) with at least one contact surface (22-36).

4. Sensor (10) according to one of claims 2 or 3,

characterized in that the media-side electrical conductor tracks (84-94) and / or the connection-side electrical conductor tracks (98-108) are formed from a different material than the sensor surfaces (46-56), in particular from a material with a lower positive standard Malpotential compared to a normal hydrogen electrode, measured at 25 ° C, 1013 hPa.

5. Sensor (10) according to one of claims 2 to 4,

characterized in that the media-side electrical conductor tracks (84-94) and the connection-side electrical conductor tracks (98-108) are formed from the same material.

6. Sensor (10) according to one of claims 3 to 5, including the claim 3,

characterized in that contact surfaces (22-36, 40, 42) and the conductor tracks (98-108) on the connection side are formed from the same material.

7. Sensor (10) according to one of the preceding claims,

characterized in that on the connection side (16) a connection cover layer (130) is applied, which in the extension area of contact surfaces (22-36, 40, 42) the connection cover layer (130) in the thickness direction has penetrating recesses (1 10-128) and which covers at least part of the through openings (72-82).

8. Sensor (10) according to claim 7, including claim 3,

characterized in that the connection cover layer (130) covers at least part of the connection-side conductor tracks (98-108).

9. Sensor (10) according to one of the preceding claims, including claim 2,

characterized in that the media cover layer (70) covers at least part of the media-side conductor tracks (84-94).

10. Sensor (10) according to one of the preceding claims, including claim 2 or 3,

characterized in that material of the connection-side and / or the media-side electrical conductor tracks (84-94) is in at least part of the through openings (72-82) in order to provide a portion of the electrically conductive connection of contact surfaces (22-36) of the Form connection side (16) with sensor surfaces (46-56) of the media side (16).

1 1. Sensor (10) according to claim 10,

characterized in that only material from the connection-side and / or the media-side electrical conductor tracks (84-94, 98-108) is located in at least some of the through openings (72-82).

12. Sensor (10) according to one of the preceding claims,

characterized in that at least two of the contact surfaces (40, 42) are connected to a temperature sensor (44).

13. Sensor (10) according to one of the preceding claims,

characterized in that the edge (12a) of the carrier plate (12) on the media side (14) in the direction parallel to the media-side surface of the carrier gerplatte (12) at a distance from a around the media cover layer (70) umlau fenden edge (70a) of the media cover layer (70) is arranged.

14. Sensor (10) according to one of the preceding claims, including claim 7,

characterized in that the edge (12a) of the carrier plate (12) on the connection side (16) in the direction parallel to the connection-side surface of the carrier plate (12) at a distance from an edge (130a) surrounding the connection cover layer (130) of the connection -Cover layer (130) is arranged.

15. Sensor (10) according to one of the preceding claims,

characterized in that the cover layer (70, 130) is a glass-like layer.

16. A method for producing a sensor (10) according to one of the preceding claims, comprising the following method steps:

Provision of a carrier plate (12) with the media side (14) facing the medium (M) during the measurement operation and with the connection side (16) opposite the media side (14) and with through openings (72-82), which, the carrier plate (12) penetrating, run between the media side (14) and the connection side (16),

Printing the connection side (16) with a first printing medium containing electrically conductive particles to form the contact surfaces (22-36, 40, 42),

Printing the media side (14) with a second printing medium containing electrically conductive particles to form the sensor surfaces (46-56),

Application of a media cover layer (70) to the printed media side (14) while leaving out sensor surface areas,

wherein when printing the connection side (16) and / or when printing the media side (14) through openings (72) are filled with the first and / or with the second printing medium.

17. The method according to claim 16,

characterized in that, prior to printing the media side (14) with the second printing medium, it comprises a step of printing the media side (14) with the first printing medium in order to form electrical conductor tracks (84-94) on the media side.

18. The method according to claim 17,

characterized in that when printing on the connection side (16) and / or when printing on the media side (14), through-openings (72-82) are only filled with the first printing medium.

19. The method according to claim one of claims 16 to 18,

characterized in that it comprises the step of applying a connection cover layer (130) to the printed connection side (16) while leaving out contact surface areas.

20. The method according to claim one of claims 16 to 19,

characterized in that it has at least one step of burning the carrier plate (12) provided with at least one material application.