SENSOR ARRANGEMENT AND METHOD OF PUTTING SUCH AN ARRANGEMENT INTO OPERATION

Abstract

A sensor arrangement includes a storage chamber comprising an interior space, containing a liquid, with an opening, a reference terminal lead which contacts liquid and can be connected to a superordinate unit, and a sensor tube comprising a sensitive region for detecting a measured quantity of the measuring medium and a measuring terminal lead. The sensitive region can be electrically connected to the superordinate unit. The sensor tube can be moved from a first position into a second position. The sensitive region is located in the interior space of the storage chamber in a first position and outside the storage chamber in the second position. The storage chamber, the opening, and the sensor tube, in the first position, are configured such that the reference/storage/calibration liquid is prevented from escaping from the interior space, and, in the second position, configured such a liquid transport is formed.

Claims

1. A sensor arrangement, comprising a storage chamber, comprising an interior space that contains a reference/storage/calibration liquid, with an opening, and a reference terminal lead which contacts the reference/storage/calibration liquid and can be connected to a superordinate unit, and a sensor tube, comprising a sensitive region for detecting a measured quantity of the measuring medium, and a measuring terminal lead, wherein the sensitive region can be electrically connected to the superordinate unit via the measuring terminal lead, wherein the sensor tube is movably arranged in the opening of the storage chamber and can be moved from a first position to a second position, wherein the sensitive region is arranged on/in the sensor tube such that, in the first position, it is located in the interior space of the storage chamber and, in the second position, it is located outside the storage chamber, wherein the storage chamber, the opening, and the sensor tube are designed such that, in the first position, the reference/storage liquid is prevented from escaping from the interior space, and wherein the storage chamber, the opening, and the sensor tube are designed such that a liquid transport is formed in the second position.

2. The sensor arrangement of claim 1, wherein the storage chamber is arranged coaxially around the sensor tube.

3. The sensor arrangement of claim 1, comprising a measuring cell for receiving measuring medium, wherein the measuring cell is connected to the storage chamber via the opening, and wherein, in the second position, the sensitive region is located in the measuring cell.

4. The sensor arrangement of claim 3, wherein the measuring cell and the storage chamber are designed in one piece.

5. The sensor arrangement of claim 1, comprising a transport-forming element which is arranged such that, in the second position of the sensor tube, the liquid transport is designed as a liquid transport filled with reference/storage/calibration liquid.

6. The sensor arrangement of claim 5, wherein the transport-forming element is arranged on or at the sensor tube.

7. The sensor arrangement of claim 6, wherein the transport-forming element is designed as an annular diaphragm.

8. The sensor arrangement of claim 6, wherein the transport-forming element is designed as a surface texture of the sensor tube, such as one or more axially arranged slits, roughing, or tapering.

9. The sensor arrangement of claim 1, wherein a seal is arranged in the opening, which seal seals off the storage chamber in the first position.

10. The sensor arrangement of claim 5, wherein the transport-forming element is arranged annularly in the opening, and the sensor tube at an end region comprises a plate seal which radially surrounds the transport-forming element and seals off the storage chamber in the first position.

11. The sensor arrangement of claim 5, wherein the measuring cell comprises a second opening and the transport-forming element is arranged in the second opening, and the sensor tube at an end region comprises a plate seal which radially surrounds the transport-forming element and seals off the storage chamber in the first position.

12. The sensor arrangement of claim 1, wherein the storage chamber comprises one or more filling openings for reference/storage/calibration liquid.

13. The sensor arrangement of claim 1, a housing that is in mechanical contact with the sensor tube, and a movement of the housing causes a movement of the sensor tube.

14. The sensor arrangement of claim 1, wherein the housing is arranged like a sleeve around the storage chamber.

15. The sensor arrangement of claim 1, wherein the sensor arrangement is designed as a potentiometric sensor arrangement with the sensor tube as a measuring half-cell and the storage chamber as a reference half-cell.

16. The sensor arrangement of claim 1, wherein the sensitive region is designed as an ion-selective membrane.

17. The sensor arrangement of claim 16, wherein the membrane is designed as a glass membrane.

18. The sensor arrangement of claim 16, wherein the membrane is designed as an enamel layer.

19. The sensor arrangement of claim 1, wherein the reference/storage/calibration liquid is formed from an aqueous electrolyte solution.

20. The sensor arrangement of claim 1, wherein the electrolyte solution contains, in a predetermined activity or concentration, an analyte that correlates with the measured quantity.

21. The sensor arrangement according to claim 1, wherein the electrolyte solution contains ions forming the potential of the reference terminal lead.

22. A method for placing a sensor arrangement into operation, comprising the steps of: sterilizing the sensor arrangement, calibrating the sensor arrangement, and moving the sensor tube from the first position into the second position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] This is explained in more detail with reference to the following Figures.

[0048] FIG. 1a/b show the claimed sensor arrangement in a first or second position.

[0049] FIG. 2 shows the claimed sensor arrangement in one embodiment in the second position.

[0050] FIG. 3a-d show the claimed sensor arrangement in one embodiment in a first or second position, with a detailed view.

[0051] FIG. 4a/b how the claimed sensor arrangement in one embodiment in a first or second position.

[0052] FIG. 5a/b show the claimed sensor arrangement in one embodiment in a first or second position.

[0053] In Figures, the same features are labeled with the same reference signs.

DETAILED DESCRIPTION

[0054] The claimed sensor arrangement in its entirety bears the reference sign 1 and is shown in a first position in FIG. 1a.

[0055] FIG. 1a and FIG. 1b show a first example of a sensor arrangement 1, for example with a housing 13 formed from a plastic with hygiene approval. The sensor arrangement 1 can be connected to a process container, such as a process container in disposable technology, for example a fermenter, bag, pouch, sac, chamber, container, a hose or pipeline with a rigid or flexible wall made of a plastic with hygiene approval, or the like. An embodiment for connecting to a hose or pipeline is shown. The process container is referred to below as a measuring cell 5. The measuring cell 5 comprises an inlet 14 and an outlet 15. In the embodiment for another container, the sensor arrangement 1 then has a connecting strip (not shown; as a type of flange) which can be glued or welded to the wall of the process container. Accordingly, the sensor arrangement 1 then does not comprise an inlet 14 and outlet 15; rather, the sensor arrangement 1 is adapted to the container to be connected.

[0056] A plastic, e.g., PE, PPSU, PVDF, or PEEK, for example, is considered as a material for the measuring cell 5.

[0057] The sensor arrangement 1 comprises a storage chamber 2 with an interior space 2a which is designed to receive a reference/storage/calibration liquid, and a reference terminal lead 4 which can be connected to a superordinate unit (not shown). The storage chamber 2 has, for example, a circular cylindrical shape with. In one embodiment, the storage chamber 2 has an elliptical or polygonal base surface, for instance has a quadrangular or pentagonal design. The storage chamber 2 comprises one or more filling openings 22 for reference/storage/calibration liquid.

[0058] In the embodiment in FIG. 1a, the sensor arrangement 1 comprises a measuring cell 5. The storage chamber comprises an opening 6, such as a circular opening. The measuring cell 5 and the storage chamber 2 are, for example, manufactured in one piece, wherein they are connected to one another via the opening 6. Alternatively, the two can be manufactured from separate parts and be connected to one another accordingly, for instance by joining, gluing, or welding. The measuring cell 5 is designed to receive measuring medium 11 via the inlet and outlet 14, 15 (see above). The measuring cell 5 is, for example, a flow cell which can be introduced into a line system. This is shown in FIG. 1a/b.

[0059] A sensor tube 7, for example a cylindrical sensor tube, is mounted in an axially movable manner in the opening 6, i.e., the opening 6 forms a guide channel. The sensor tube 7 is movable at least from a first position (FIG. la, storage position) into a second position (FIG. 1b, measurement position). The storage chamber 2 is thus arranged coaxially around the sensor tube 7. In one embodiment, the opening 6 is arranged off-axis, i.e., is displaced from the main axis of the storage chamber. This can be the case given an elliptical basic shape.

[0060] The sensor arrangement 1 is preferably designed as a single-use sensor, i.e., the sensor tube 7 can be displaced only once from the first into the second position. The sensor tube 7 comprises a sensitive region 8 for detecting a measured quantity of the measuring medium 11, and a measuring terminal lead 9, wherein the sensitive region 8 can be connected to the superordinate unit (not shown) via the measuring terminal lead 9. In the first position, the sensitive region 8 is located in the storage chamber 2 and, in the second position, it is located in the measuring cell 5. See below for details regarding the measurement.

[0061] The storage chamber 2, the opening 6, and the sensor tube 7 are designed such that, in the first position, the reference/storage/calibration liquid is prevented from escaping from the interior space 2a. The storage chamber 2, the opening 6, and the sensor tube 7 are designed such that a liquid transport is formed in the second position. This is explained below.

[0062] For this purpose, the sensor arrangement 1 comprises, for instance, a transport-forming element 10, 16, 26 which is arranged such that, in the second position of the sensor tube 7, a liquid connection exists between the interior space 2a of the storage chamber 2 and the outside, i.e., for instance, to the measuring cell 5. The transport-forming element 10, 16, 26 is arranged such that, in the second position of the sensor tube 7, the liquid transport is designed as a liquid transport filled with reference/storage/calibration liquid. A fluid channel from the interior space 2a to the outside is thus formed. The transport-forming element 10 is often referred to as a “liquid”. The transport-forming element 10 is arranged such that, in the first position of the sensor tube 7, the transport-forming element 10 is arranged in the storage chamber 2.

[0063] FIG. 1a and FIG. 1b show an embodiment in which the transport-forming element 10 is arranged on or at the sensor tube 7, and in fact as a component (i.e., as an interchangeable element), such as an annular diaphragm. FIG. 2 shows an embodiment of the transport-forming element 10 as a surface texture of the sensor tube 7, for instance as one or more axially arranged slits, roughings, or taperings. FIG. 2 shows the second position.

[0064] The storage chamber 2, the measuring cell 5, and the sensor tube 7 are designed such that, in the first position, the storage chamber 2 is sealed with respect to the measuring cell 5. The present gaps are filled or evened out by sealing elements 12. A hermetic sealing of the two chambers 2, 5 is generated by the sealing elements 12 and the sensor tube 7. During the axial movement of the sensor tube 7, the seal is completely maintained, so that no exchange of fluids takes place between the chambers 2, 5.

[0065] The storage chamber 2 is closed after its filling. A fluid is contained therein, which serves for the moist storage of the sensitive region 8 and of the transport-forming element 10. As mentioned, the reference terminal lead 4 is located in the storage chamber 2. Via the known pH value of the storage fluid, a calibration can be performed in the first position (storage position) before placement into service. A closed measuring circuit is present in the storage position (i.e., the first position) since reference terminal lead 4 and sensitive region 8 are located in the same medium.

[0066] Upon being placed into service, the sensor tube 7 is moved into the measuring cell 5 such that the sensitive region 8 is located entirely in the measuring cell 5, and such that regions of the transport-forming element 10 are located both in the storage chamber 2 and in the measuring cell 5. If measuring medium 11 is guided through the measuring cell 5 (via inlet 14 and outlet 15), it contacts the sensitive region 8 and the transport-forming element 10 on the side of the measuring cell 5, wherein a reference solution contacts the reference terminal lead 4 and the transport-forming element 10 on the side of the storage chamber 2. The storage chamber 2 does not move. The reference terminal lead 4 remains in the storage chamber 2 and does not move.

[0067] A displacement mimic, which is connected to the sensor tube 7, serves to move the sensor tube 7. The displacement mimic comprises a sleeve bushing 21, which is rigidly connected to the sensor tube 7 so that an axial movement of the sleeve bushing 21 toward the measuring medium 11 causes an axial movement of the sensor tube 7 in the direction of the measuring medium 11.

[0068] As mentioned, the sensor arrangement 1 comprises a housing 13, wherein the housing 13 comprises the sleeve bushing 21. An axial movement of the housing 13 thus causes a movement of the sensor tube 7. A plastic, for instance PC, COC, PE, PPSU, PVDF, or PEEK, for example, is considered as a material for the housing 13.

[0069] In the first position, the sensor tube 7 also projects from the storage chamber 2 at the upper end thereof (i.e., toward the displacement mimic). In order that no liquid flows out, the storage chamber 2 comprises one or more corresponding seals 25.

[0070] The two end positions that can be reached by moving the sensor tube 7 are shown in FIG. 1a and FIG. 1b. In FIG. 1a, the sensor tube 7 is retracted completely into the storage chamber 2 in the first position so that only its front-side base surface is still in contact with the environment. In FIG. 1b, in the second position, a portion of the sensor tube 7, primarily the sensitive region 8, is extended out of the storage chamber 2. Both end positions can be predetermined in a manner known per se by stops formed in the displacement mimic, the housing 2, the sleeve 21, and/or the sensor tube 7 5. An end position latching or end position fixing can also be provided in a manner familiar to the person skilled in the art.

[0071] FIG. 3a and FIG. 3b show an embodiment of the sensor arrangement in the first and second position, respectively. The transport-forming element 26 is thereby arranged annularly in the opening 6, and the sensor tube 7 comprises at the measuring cell-side end a plate seal 17 with an axially or radially arranged sealing element 17a, 17b (FIG. 3c and FIG. 3d show both embodiments, wherein only one sealing element 17a, 17b can also be used), wherein the plate seal 17 radially surrounds the transport-forming element 26 and seals the storage chamber 2 with respect to the measuring cell 5 in the first position, and exposes the diaphragm to the measuring medium in the second position. FIG. 3c and FIG. 3d show this in detail.

[0072] FIG. 4a or FIG. 4b show an embodiment of the sensor arrangement in the first and second position, respectively. The measuring cell 5 thereby comprises a second opening 18, and the transport-forming element 16 is arranged in the second opening. The sensor tube 7 comprises at the measuring cell-side end a plate seal 17, which radially surrounds the transport-forming element 16 and seals the storage chamber 2 with respect to the measuring cell 5 in the first position.

[0073] As mentioned, the transport-forming element 10, 16, 26 establishes the electrical connection to the reference cell upon movement of the sensor tube 7. The transport, i.e., the liquid transport in the wording of the claim, is formed after displacement of the sensor tube 7 into the second position. The transport-forming element 10, 16, 26 is thereby the prerequisite for the function of the storage chamber as a reference cell. Various embodiments of the transport-forming element 10, 16, 26 are possible:

[0074] constituent of the movable sensor element

[0075] as a ring element, for instance as a diaphragm (embodiment as a part or component, e.g., FIG. 1a/b)

[0076] as a surface texture (embodiment as a functional surface, e.g., FIG. 2, FIG. 5a/b)

[0077] constituent of the complete assembly (embodiment as a component)

[0078] with contacting the sensor tube (e.g., FIG. 3a/b)

[0079] without contacting the sensor tube (e.g., FIG. 4a/b)

[0080] A liquid of known composition in the storage chamber 2 serves for the moist storage of the sensor tube 7 stored therein (first position; of the sensitive region 8 and of the transport-forming element 10). The same liquid serves for the calibration of the sensor before placement into operation, and the same liquid serves for referencing during the measurement. The liquid remains in the storage chamber 2, whereas the sensor tube 5 can be moved into the measuring cell 5.

[0081] In the exemplary embodiments illustrated here, the sensor arrangement 1 comprises a potentiometric sensor with a pH measuring half-cell and a reference half-cell.

[0082] The measuring half-cell is formed by the measuring cell 5 with the sensor tube 7 in the second position. For this purpose, the sensor tube 7 comprises the sensitive region 8. In one embodiment, the sensitive region 8 is designed as an ion-selective membrane, such as a pH-sensitive membrane. The membrane is a glass membrane. The sensitive region 8 can thereby also be designed as a cap.

[0083] The measuring terminal lead 9, which is in electrical contact with the sensitive region 8, is located in the interior of the sensor tube 7. The interior of the sensor tube 7 forms the measuring half-cell chamber, wherein a liquid or gel-like internal electrolyte can be received therein. In the present example, the internal electrolyte is a buffer solution with a predetermined chloride concentration. The measuring terminal lead 9 contacts the internal electrolyte or the electrically conductive inner surface of the measuring half-cell and is electrically conductively connected to a contact point outside the measuring half-cell chamber (not illustrated in Figures; a superordinate unit, for instance). The measuring terminal lead 9 can be a metal wire, for example a chlorided silver wire.

[0084] The measuring half-cell chamber, i.e., the sensor tube 7, is closed on the rear side, for example by means of a plastic casting compound or by fusing or gluing.

[0085] In one embodiment of the sensitive region 8, the sensitive region is designed as a layer which rests on the electrically conductive terminal lead. In this embodiment, the terminal lead is designed as a solid terminal lead. The layer may be an ion-sensitive enamel layer 23, which is shown in FIG. 5a and FIG. 5b in the first and second positions and is explained below:

[0086] On its outside, the sensor tube 7 is covered with a system of layers. In this exemplary embodiment, the sensor tube 7 has a base layer 24 of an insulating material, for example an insulating enamel layer, on the front side. An ion-selective enamel layer 23, which in the present example comprises pH glass, is arranged above the base layer. On the rear side, the ion-selective layer is electrically contacted by a metallic terminal lead. The discharge takes place in the longitudinal direction, for example along the outer lateral surface of the sensor tube 7 up to the end face with the back surface of the sensor tube 7 opposite the ion-selective layer 23. The terminal lead is embedded in an electrically insulating coating, for example an insulating enamel layer, which electrically insulates the terminal lead from the sensor tube 7 and from the environment of the measuring half-cell. The coating may be formed from a plurality of individual layers of identical or different glass compositions. The terminal lead may, for example, be designed as a metallic coating on a layer of the coating.

[0087] In a modification of the exemplary embodiment, the sensor tube 7 can be designed to be electrically conductive, for instance metallic, and then itself serve as a terminal lead. In this instance, the ion-selective enamel layer is applied directly to the sensor tube 7. A surface region not covered by the ion-selective enamel layer 23, for example the lateral surface of the sensor tube 7, may be covered by an electrically insulating coating, for example an insulating enamel, and thus be insulated from the environment of the measuring half-cell.

[0088] “Enamel electrodes” normally have a metallic base body to which an ion-selective, such as a pH-selective, glass layer 23 is applied. The ion-selective layer may be an enamel coating.

[0089] According to the definitions/labeling standards, RAL registration RAL-RG 529 A2 from July 2007 by RAL Deutsches Institut fur Güatesicherung and Kennzeichnung e. V. [RAL German Institute for Quality Assurance and Certification, registered association], a vitreous material that is produced by completely or partially melting substantially oxidic raw materials is referred to as an enamel. The inorganic preparation thus produced is applied with additives in one or more layers to workpieces made of metal or glass and fused at temperatures above 480° C. Base constituents of (ion-selective) enamel layers are, for example, one or more of the oxides silicon oxide, sodium oxide, potassium oxide, calcium oxide, magnesium oxide, and aluminum oxide. An ion-selective glass, e.g., pH glass, applied to a metallic base body using such a method is therefore also referred to hereinafter as an ion-selective enamel layer or, in the case of an enamel layer specifically selective for hydronium ions, as a pH enamel layer, and a corresponding electrode as an enamel electrode. In this exemplary embodiment, no internal electrolyte is used.

[0090] In each of the above-described embodiments, outside the measuring half-cell chamber and the reference half-cell chamber (see below), a measuring circuit 20 can be arranged in the housing 13, which measuring circuit is electrically conductively connected to the measuring terminal lead 9 and is designed to detect a potential difference between the measuring terminal lead 9 and the reference terminal lead 4 (not shown in Figures). By means of a plug connection, for instance a galvanically isolating connection, for example an inductive connection, or a contact plug connection, between a plug head 19 connected to the housing 13 and a complementary counterpart (not shown in the Fig.), the measuring circuit can be designed to be connected to a superordinate electronic data processing device for transmitting measurement signals and/or data.

[0091] The reference half-cell is formed by the storage chamber 2 (which forms the reference half-cell chamber) with the reference terminal lead 4. The reference half-cell chamber contains the reference/storage/calibration liquid, such as potassium chloride or sodium chloride. In order to combine all functions, the reference/storage/calibration liquid must have a defined anion concentration for the reference electrode (e.g., 3 mol/l Cl—), a defined and stable pH value (calibration), and a composition (storage) that is advantageous for maintaining the swelling layer. Arranged in the storage chamber 2 is the reference terminal lead 4, for example a chlorided silver wire, which contacts the reference/storage/calibration liquid and is electrically conductively connected to a further contact point outside the reference half-cell chamber (not shown in Figures).

[0092] The reference half-cell chamber is closed on the rear side, for example by means of a plastic casting compound or by fusing or gluing.

[0093] The sensor arrangement 1 comprises a temperature sensor 3 which is arranged, for example, in the sensor tube 7. The temperature sensor 3 is electrically connected to the measuring circuit 20.