ELECTROCHEMICAL SENSOR WITH EXCHANGEABLE ELECTRODE ASSEMBLY

Abstract

The present disclosure relates to a method for producing an exchangeable electrode assembly, with at least one sensor body and at least a first electrode, for an electrochemical sensor for determining the concentration of an analyte in a gaseous or liquid measurement medium, a corresponding electrode assembly, and an electrochemical sensor with an electrode assembly according to the present disclosure. In order to produce the electrode assembly, the following method steps are performed: providing a sensor body, and applying at least a first electrically-conductive material to a first sub-region of the sensor body for producing a first electrode of the electrode assembly.

Claims

1. A method for producing an exchangeable electrode assembly for an electrochemical sensor for determining the concentration of an analyte in a gaseous or liquid measurement medium, the method comprising: producing a sensor body; and applying at least a first electrically conductive material to a first subregion of the sensor body to generate a first electrode of an electrode assembly.

2. The method of claim 1, wherein the sensor body includes at least a first mounting unit for removably mounting the electrode assembly on at least one component of the electrochemical sensor.

3. The method of claim 1, wherein the sensor body is made of a non-conductive material, including a plastic or a ceramic.

4. The method of claim 1, the method further comprising introducing a lattice structure or a profile into at least a portion of the sensor body during or after the producing the sensor body.

5. The method of claim 1, the method further comprising applying at least one additional electrode to another subregion of the sensor body.

6. The method of claim 1, wherein the at least one electrode is applied to the sensor body using galvanization, using chemical deposition, using a chemical vapor deposition method based upon a redox reaction, using a physical vapor deposition method, or using fire gilding.

7. The method of claim 1, wherein the electrode assembly is produced in the form of an injection-molded circuit carrier.

8. The method of claim 7, the method further comprising: producing the sensor body using a plastic material doped with a laser-activatable metal compound as a plastic additive; structuring the sensor body using a laser at least in the first subregion such that conductive metal particle seeds are generated from the metal compound; and at least partially galvanizing the sensor body in the first subregion using at least the first electrically conductive material to generate the first electrode of the electrode assembly.

9. An electrode assembly for an electrochemical sensor for determining the concentration of an analyte in a gaseous or liquid measurement medium, the electrode assembly comprising: a sensor body made of a plastic material doped with a laser-activatable metal compound as a plastic additive, wherein a laser is used to generate conductive metal particle seeds from the metal compound in at least a first subregion of the sensor body; and a first electrode of the electrode assembly formed by applying at least a first electrically conductive material to the first subregion of the sensor body.

10. The electrode assembly of claim 9, the electrode assembly further comprising at least one electrode assembly contacting unit for removably and electrically connecting at least the first electrode to at least one component of the electrochemical sensor.

11. The electrode assembly of claim 9, wherein the sensor body includes a portion having a lattice structure or a profile.

12. An electrochemical sensor for determining the concentration of an analyte in a gaseous or liquid measurement medium, the sensor comprising: an electrolyte chamber at least partially filled with an electrolyte and separated from a measurement medium by a membrane; and an electrode assembly comprising: a sensor body made of a plastic material doped with a laser-activatable metal compound as a plastic additive, wherein a laser is used to generate conductive metal particle seeds from the metal compound in at least a first subregion of the sensor body; and a first electrode of the electrode assembly formed by applying at least a first electrically conductive material to the first subregion of the sensor body, wherein the first electrode of the electrode assembly protrudes into the electrolyte chamber and at least partially contacts the electrolyte.

13. The electrochemical sensor of claim 12, the sensor further comprising at least one electrode assembly contacting unit for removably and electrically connecting at least the first electrode to at least one component of the electrochemical sensor.

14. The electrochemical sensor of claim 12, wherein the sensor body includes at least a first mounting unit for removably mounting the electrode assembly on at least one component of the electrochemical sensor.

15. The electrochemical sensor of claim 14, the sensor further comprising a sensor housing including a second mounting unit configured to be complementary to the first mounting unit of the electrode assembly, wherein the electrode assembly is removably mountable on the sensor using the first and second mounting units.

16. The electrochemical sensor of claim 12, the sensor further comprising at least a second contacting unit for electrically connecting the electrode assembly to an electronics unit of the sensor.

17. The electrochemical sensor of claim 12, wherein the sensor body includes a portion having a lattice structure or a profile, and wherein the electrode assembly is arranged such that the portion faces the membrane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present disclosure is explained in more detail below with reference to FIGS. 1 through 4. These show:

[0037] FIG. 1A shows a schematic of an electrochemical sensor according to the prior art;

[0038] FIG. 1B shows a schematic of an electrochemical sensor according to the prior art which functions according to the amperometric principle;

[0039] FIG. 2A shows a schematic of an embodiment of an electrode assembly according to the present disclosure with a single electrode;

[0040] FIG. 2B shows a schematic of an embodiment of an electrode assembly according to the present disclosure with two electrodes;

[0041] FIG. 3A shows a schematic of an embodiment of an electrode assembly according to the present disclosure with two electrodes before mounting to a sensor;

[0042] FIG. 3B shows a schematic of an embodiment of an electrode assembly according to the present disclosure with two electrodes after mounting to a sensor;

[0043] FIG. 3C shows a schematic top view of a segment of a sensor body of an embodiment of an electrode assembly according to the present disclosure;

[0044] FIG. 4A shows a schematic of an electrode assembly according to the present disclosure, the electrode assembly mounted on the sensor with a mounting unit in the form of a clamp; and

[0045] FIG. 4B shows a schematic of an electrode assembly according to the present disclosure, the electrode assembly mounted on the sensor with a mounting unit in the form of a screw connection.

DETAILED DESCRIPTION

[0046] FIG. 1A shows a schematic representation of an electrochemical sensor 1 for determining the concentration of an analyte 17b in a gaseous or liquid measurement medium 17a in a container 17 with a measuring electrode 7 and a second electrode 12 also called a reference electrode. The measuring electrode 7 is brought into electrolytic contact with the measurement medium 17a by means of an electrolyte chamber 15 filled with an electrolyte 15a and ending on the medium side with a membrane 5.

[0047] In order to illustrate the design of such a sensor 1, FIG. 1B shows a representation of a longitudinal section of an amperometric sensor 1. The present disclosure is, however, in no way limited to amperometric sensors. Rather, it is used for the most varied electrochemical sensors 1 with an electrolyte 15a and/or a membrane 5.

[0048] For accommodating an electronics unit, the substantially cylindrical sensor 1 comprises a membrane module 2 arranged in a region hereafter referred to as ‘on the membrane side,’ a sensor shaft 3 arranged in a region hereafter referred to as ‘on the connection side,’ and a sensor plug head, which is connected on the connection side to the sensor shaft 3 and which is, however, not shown in FIG. 1.

[0049] The membrane module 2 comprises a membrane cap 4, inside of which a membrane 5 is pressed against the membrane cap 4 in a hermetically-sealed manner by means of a fixable sleeve. In the region on the connection side, the membrane module 2 can be removably connected to a central sensor tube 6.

[0050] The measuring electrode 7 of the sensor 1, which measuring electrode is given by, for example, an electrode 9 fused into an electrode body 8 in, for example, the form of a wire, usually forms a cathode in the case of an amperometric sensor. In the region facing the membrane 5, or the region on the membrane side, the measuring electrode 7 ends in an end face 10 for example, in the form of a spherical surface or a spherical calotte. In the region of the end face 10, the measuring electrode 7 touches the membrane 5 at least in a, for example, roughened, or structured, sub-area. An annular gap 11 remains between the measuring electrode 7 and the inner wall of the membrane cap 4, through which gap liquid can penetrate between the membrane 5 and the end face 10 of the measuring electrode 7.

[0051] In the region of the measuring electrode 7 facing away from the membrane 5, the measuring electrode 7 is surrounded by a second electrode 12, in this case the anode, which is designed in the shape of a sleeve. Both electrodes 7, 12 are, for example, connected to an electronics unit (not shown) accommodated in the sensor plug head via a plug-in connection 13 and connecting lines 14.

[0052] The membrane cap 4, the inner wall of the membrane module 2, the sensor tube 6, the second electrode 12, the measuring electrode 7, and the membrane 5 thus completely enclose an electrolyte chamber 15 inside the membrane module 2, which electrolyte chamber 15 is filled with an aqueous electrolyte solution 15a. In the annular gap 11, a thin electrolyte film forms. This region is also referred to as the measuring chamber 16. The at least partial roughening or structuring of the end face 10 ensures that the electrolyte film is of a desired and sufficient thickness. Alternatively, so-called spacers (not shown here) can also be introduced in-between.

[0053] If the electrochemical sensor 1 is, however, designed as, for example, a potentiometric sensor, e.g., for determining the concentration or partial pressure of CO.sub.2 in a measurement medium, the measuring electrode comprises a pH-selective electrode, such as a pH glass electrode, or a pH-selective semiconductor electrode, such as a pH ISFET electrode. The rest of the sensor design is substantially analogous to the example shown in FIG. 1. An analyte, such as CO.sub.2, diffused through the membrane 5 changes the pH value of the electrolyte 15a in the measuring chamber 16 in the case of CO.sub.2, according to the equilibrium, with hydrogen carbonate (i.e., the Severinghaus principle). The pH value change is measured by means of the pH-selective electrode, and the CO.sub.2 concentration of the measurement medium is determined therefrom.

[0054] According to the present disclosure, an exchangeable electrode assembly 18 is provided for an electrochemical sensor 1. Advantageous embodiments of such an electrode assembly 18 are shown in FIGS. 2A and 2B by way of example. The electrode assembly 18 comprises a sensor body 19, which is designed as a solid, cylindrical component in the case of the embodiment according to FIG. 2A. The sensor body 19 is produced from an electrically non-conductive material, such as a ceramic or a plastic. In the case where the LDS method is, for example, to be used for the production of the electrode assembly 18, the plastic is a laser-activatable plastic.

[0055] In a region M of the sensor body 19, which region is facing the respective measurement medium 17a in the installed condition in the sensor 1 (not shown in FIGS. 2A and 2B), a first electrode 20 in the form of a thin layer is applied in a first subregion 20a. Depending upon the embodiment of the sensor body 19, the electrode 20 can either end substantially flush with the bounding surface A of the sensor body 19, as shown in FIG. 2A, or protrude beyond the bounding surface, said bounding surface facing the measurement medium 17a. For the embodiment shown, the base body 19 is further provided with a first electrode assembly contacting unit 21 for electrically contacting the electrode 20, which is designed as a metallic contact feedthrough extending through the sensor body 19.

[0056] In contrast to the embodiment according to FIG. 2A, the sensor body 19 of the electrode assembly 18 of FIG. 2B is designed as a hollow body. The electrode assembly 18 of this embodiment has two electrodes 20, 22, which are respectively arranged in two subregions 20a, 22a, in the region M of the sensor body 19 facing the measurement medium 17a. The two electrodes 20 and 22 are respectively electrically contacted by means of an electrode assembly contacting unit 21 and 23, respectively.

[0057] Without loss of generality, FIGS. 3A-3C and FIGS. 4A and 4B respectively relate to embodiments of the electrode assembly 18 according to the present disclosure with two electrodes 20, 22. Already explained reference symbols are therefore not necessarily discussed again in detail. The electrode assembly contacting units 21, 23 of the illustrated exemplary embodiment are respectively composed of an associated electrode assembly contact feedthrough 21a, 23a and an electrode assembly contact pin 21b, 23b. In such an embodiment, the electrochemical sensor has two sensor contacting units 24, 25 complementary to the electrode assembly contacting units 21, 23, which sensor contacting units 24, 25 are composed of sensor receptacles 24b, 25b complementary to the electrode assembly contact pins 21b, 23b for the same, as well as of two sensor contact feedthroughs 24a, 25a. As can be seen in FIG. 3B, after the electrode assembly 18 is mounted onto the sensor 1, the electrode assembly contact pins 21b, 23b protrude into the sensor receptacles 24b, 25b such that an electrical contact is established.

[0058] FIG. 3C shows a schematic top view of the first subregion 20a of the sensor body 19. Into a further subregion 26, a lattice structure 26a is introduced, which serves as, for example, a spacer or placeholder between the membrane 5 and the respective electrode 20, 22 inside the measuring chamber 16.

[0059] FIGS. 4A and 4B show two preferred embodiments of an electrochemical sensor 1 with an electrode assembly 18 according to the present disclosure with a first mounting unit 27. A second mounting unit 28, which is designed to be complementary to the first mounting unit 27, is mounted on the sensor tube 3 of the sensor 1. By means of the first and the second mounting units 27, 28, the electrode assembly 18 can be removably mounted on the respective sensor 1 especially, on the sensor tube 3 of the sensor 1. For the embodiments shown here by way of example, the mounting is effected, according to FIG. 4A, by means of a clamping connection and, according to FIG. 4B, by means of a screw connection. In doing so, for FIG. 4A, the first mounting unit 27 is designed in the form of a clamping edge or a holder, and the second mounting unit 28 is designed in the form of a clamping device. For the screw connection according to FIG. 4B, the first mounting unit 27 is also realized in the form of a clamping edge or a holder, while the second mounting unit 28 is a thread. In order to mount the electrode assembly 18 on the sensor 1, a sleeve nut 29 is further required according to this example, which sleeve nut can either be considered a separate component or be assigned to one of the two mounting units 27, 28.

[0060] It goes without saying that all conceivable mounting methods known to the person skilled in the art are available for the mounting, which mounting methods furthermore all fall under the present disclosure. It should be pointed out that, depending upon the selected mounting method, two mounting units 27, 28 are not necessarily required, but that the mounting can possibly also be realized by means of a single mounting unit 27, 28. In particular, a mounting unit 27, 28 is, in principle, not necessarily required. For example, the electrode assembly 18 can also be mounted on the sensor 1 by means of a membrane cap 4 (not shown) of the respective sensor 1.