DE102017112225A1 - A method of manufacturing a housing and housing for a reference electrochemical half-cell - Google Patents

Abstract

The invention relates to a method for producing a housing (3) for an electrochemical reference half-cell (1), wherein the housing (3) has at least one chamber (2a, 2b) for receiving an electrolyte (12a, 12b), wherein in an outer wall ( 4) of the chamber (2a, 2b) an electrochemical transfer (5,5a, 5b) is arranged, by means of which an electrolytic contact between an in the chamber (2a, 2b) can be arranged in the electrolyte (12a, 12b) and one outside the chamber ( 2a, 2b) can be produced disposable medium. The method is characterized in that, for at least one chamber (2a; 2b) or at least one of the chambers (2a; 2b), the outer wall (4) made of a material is in one piece and the electrochemical transfer (5,5a, 5b) in the Outside wall (4) by means of at least one in the outer wall (4) introduced energy input (.DELTA.E1, .DELTA.E2, .DELTA.E3) is generated, wherein by the energy input (.DELTA.E1, .DELTA.E2, .DELTA.E3) in the region of the electrochemical transfer (5,5a, 5b) pores (6) are introduced into the material of the outer wall (4).

Description

The invention relates to a method for producing a housing and a housing for a reference electrochemical half-cell. The housing has at least one chamber for receiving an electrolyte, wherein in an outer wall of the chamber, an electrochemical transfer is arranged, by means of which an electrolytic contact between an arrangeable in the chamber electrolyte and an outside of the chamber can be produced medium can be produced.

Reference half cells are used in various electrochemical sensors. Electrochemical sensors are used in the laboratory and process measuring technology in many areas of chemistry, biochemistry, pharmacy, biotechnology, food technology, water management and environmental metrology for the analysis of measuring media, in particular of measuring liquids. By means of electrochemical measurement techniques, it is possible to record, for example, activities of chemical substances, for example ions, and thus correlated measured variables in liquids. The substance whose concentration or activity is to be measured is also called analyte. Electrochemical sensors may be, for example, potentiometric or amperometric sensors.

Potentiometric sensors usually comprise a measuring half cell and a reference half cell as well as a measuring circuit. The measuring half-cell forms in contact with the measuring medium, e.g. a measuring liquid, depending on the concentration or activity of the analyte in the measuring medium potential, while the reference half cell provides a stable, independent of the concentration of the analyte reference potential. The measuring circuit generates a measuring signal representing the potential difference between the measuring half cell and the reference half cell. If necessary, the measuring signal is output by the measuring circuit to a superordinated unit, for example a measuring transducer, connected to the sensor, which further processes the measuring signal. The measuring half-cell comprises a potential-forming element which, depending on the type of potentiometric sensor, may comprise, for example, a redox electrode, an analyte-sensitive coating or an ion-selective membrane.

Examples of potentiometric sensors are ion-selective electrodes (ISE). An ion-selective electrode has a housing sealed by the ion-selective membrane serving as a potential-generating element, in which an inner electrolyte is accommodated, and a drain member, which are in contact with the inner electrolyte. If the measuring medium is in contact with the potential-forming element, a change in the activity or concentration of the analyte in the measuring medium causes a relative change in the equilibrium galvanic voltage between the measuring medium and the measuring liquid in contact with the potential-forming element via the inner electrolyte Deriving effected. The diverting element is electrically conductively connected to the measuring circuit. A special case of such an ion-selective electrode is the known pH glass electrode having a chamber sealed by a pH-sensitive glass membrane with an inner electrolyte contained therein and a buffer system for adjusting a stable pH, and a drain element immersed therein. Ion-selective electrodes are described, for example, in "Working with Ion-Selective Electrodes", K. Cammann, H. Galster, Springer, 1996.

Further examples of sensors which require an electrochemical reference electrode are those based on electrolyte-insulator-semiconductor layer stacks (in English: electrolyte-insulator-semiconductor, in short: EIS). These layer systems can be operated, for example, capacitively or as ion-selective field-effect transistors (ISFET). The acronym "EIS" expresses that the sensor comprises a layer structure with at least one insulator coating applied to a semiconductor layer or a semiconductor substrate, which is in contact with the measuring medium serving as electrolyte in the measuring operation of the sensor. By suitable choice of the insulator coating, the sensitivity of the sensor can be adjusted such that a voltage drop occurring at the interface between the insulator layer and the measured medium serves as a measure of the analyte concentration. The already mentioned ISFET sensor also comprises such an EIS structure. In the DE 198 57 953 A1 For example, a sensor for measuring ion concentrations or the pH of a measuring medium using an ISFET is described.

Amperometric sensors may comprise, for example, a three-electrode circuit having a working electrode, a counterelectrode and a non-current-carrying reference electrode. Such a measuring device may, for example, have a, in particular potentiostatic, control circuit which is designed to predetermine a setpoint voltage between the working electrode and the reference electrode and to detect the current flowing between the working electrode and the counterelectrode. The reference electrode, which is not current-carrying, also referred to here as reference half-cell in the following, can be designed in the same way as a reference half-cell of a potentiometric measuring arrangement.

The reference half-cell of electrochemical sensors comprises a reference diverter which is in contact with a reference electrolyte. The reference electrolyte is accommodated in a chamber formed in a housing of the reference half-cell. The potential of the reference half-cell is defined by the reference electrolyte and the reference diverter. For example, if the reference electrode is a silver / silver chloride reference electrode, the reference electrolyte is a high chloride aqueous solution, typically a 3 molar potassium chloride solution, and the reference diverter is a silver chloride coated silver wire. The reference diverter is electrically connected to the already mentioned measurement circuit.

To carry out the measurement, the reference electrolyte is in electrolytic contact with the measurement medium. This contact is made by an electrochemical transfer, which consists for example of a through hole passing through the outer wall, a porous diaphragm arranged in the outer wall or a gap. The reference electrolyte may be thickened by adding a thickening agent, in particular a polymer. As a result, an immobilization of the reference electrolyte is achieved, so that the reference electrolyte is no longer flowable and can not escape through the electrochemical transfer from the housing.

Electrochemical sensors with a reference half cell and a measuring half cell are preferably accommodated in a single electrochemical sensor; for the case of potentiometric sensors, this compact design is referred to as a so-called combination electrode. In the case of pH single-rod measuring cells with high-impedance (50 MOhm <Z <10 GOhm) measuring half-cells, this encompasses, for example, the reference half cell concentric the measuring half cell. The reference half-cell has a tubular housing closed at an end region facing the measurement medium, wherein the electrochemical transfer is arranged in the end region of the reference half-cell. The tubular housing of the reference and measuring half cell further has in each case one in an end region remote from the measuring medium opening, which is closed, for example, by an additional polymer seal.

If a porous diaphragm is used as an electrochemical transfer, it must be additionally introduced into the outer wall of the housing in a joining process during the production of a housing for the reference half cell in the end region facing the measuring medium. The liquid-tight joining of the diaphragm in the outer wall represents a production engineering challenge.

In particular, the joint between the diaphragm and the outer wall is a weak point, which is sensitive to chemical, mechanical and / or thermal stresses. The latter are caused, on the one hand, by the fact that the end region of the outer wall having the diaphragm is exposed to the measuring medium. In addition, electrochemical sensors are sterilized at regular intervals; autoclaving has proved to be the method of sterilization in which the electrochemical sensor is cleaned under high temperature (about 140 ° C) and high pressure with the aid of steam. In this case, in particular, the end region of the outer wall is exposed to high pressure and / or temperature fluctuations with the diaphragm joined therein. Furthermore, if the housing and the diaphragm joined therein consist of materials with different, in particular greatly different, coefficients of thermal expansion, high temperature fluctuations always lead in principle to additional strong mechanical stresses, which act in particular in the area of the joint.

Such stresses can ultimately lead to gaps between the outer wall and the diaphragm, cracking in the outer wall and / or the diaphragm or even to a complete failure of the joints and thus to a detachment of the diaphragm from the outer wall.

The invention is therefore based on the object of specifying a method for producing a housing or a housing for a reference half cell with a high stability.

The object is solved by the features of the independent claims.

The solution according to the invention relates to a method for producing a housing for an electrochemical reference half-cell, wherein the housing has at least one chamber for receiving an electrolyte, wherein in an outer wall of the chamber, an electrochemical transfer is arranged, by means of which an electrolytic contact between a can be arranged in the chamber Electrolytes and an outside of the chamber can be arranged medium can be produced. The method is characterized in that for at least one chamber or at least one of the chambers, the outer wall made of a material is integral and generates the electrochemical transfer in the outer wall by means of at least one introduced into the outer wall energy input becomes. As a result of the introduction of energy, pores are introduced into the material of the outer wall in the region of the electrochemical transfer.

The electrochemical transfer is generated essentially by means of the energy input, with which the pores are introduced in the one-piece outer wall. A large number of pores, in particular at least ten pores, are introduced into the outer wall. Preferably, at least 21 pores are introduced into the outer wall.

This advantageously eliminates the error-prone manufacturing process in which a separately prepared diaphragm is inserted into the outer wall of a prefabricated housing.

Another advantage of the solution according to the invention is that the electrochemical transfer and the adjacent region of the outer wall manufacturing reasons, consist of the same material, and thus can not occur due to thermal stress induced stresses.

In a chamber produced by the method according to the invention, moreover, the transition between the electrochemical transfer to the adjoining region of the outer wall is substantially seamless. Thereby, a housing for a reference half cell is achieved with an increased stability.

In a development of the method according to the invention, the at least one energy input is introduced into the outer wall of the chamber by means of at least one laser. An advantage of a laser is that a precisely metered energy input is precisely introduced in a predetermined area of the outer wall. As a result, the pores are generated in a defined or predetermined area of the outer wall forming the electrochemical transfer. The pores are e.g. in a predetermined depth of the outer wall with a predetermined thickness by a defined removal of material of the laser, such as laser engraving deep generated.

In a further development of the method according to the invention, the outer wall is selectively changed by means of at least one first energy input of the at least one laser to form at least one microdefect and / or nano-defect, whereby the pores in the outer wall are generated by means of the microdefect and / or nano-defect.

As a micro-or nano defect, a defect is called, which is present in the micro or nanometer range, i. in one of about 1 micron to 900 microns (microns) and from 1 nm to 900 nm (nanometers). These include, for example, local tensions, cracks, or chemical weakenings such as substitutions, local rearrangements, and / or segregations. The pores may be characterized by one or more of these defects, e.g. represent a precursor of the pores, are generated and / or the micro- or nano-defect is itself a pore with a pore size in the micro or nanometer range. If the outer wall is made of a microcrystalline or semi-crystalline material, the defects may also be lattice defects, e.g. Point defects such as vacancies, interstitial and / or substitution atoms or higher dimensional defects such as e.g. Dislocations, grain boundaries, stacking faults and / or pores.

In one embodiment of the method according to the invention, the outer wall is selectively changed by means of the at least one laser to form a multiplicity of microdefects and / or nanodefects, the pores being produced in the outer wall by means of the microdefects and / or nanodefects.

In a further development of the method according to the invention, a substance having a foaming agent is applied to an inner and / or outer surface of the outer wall. The foaming agent is at least partially incorporated into the outer wall by means of a second energy input and at least partially decomposed and / or vaporized by means of a third, different from the second energy input, energy input in the outer wall. By means of decomposition and / or vaporization, gas bubbles create the pores in the outer wall. The decomposition is e.g. for a calcination

In particular, the substance comprising the foaming agent and the energy inputs are adapted to the material of the outer wall in such a way that the substance having the foaming agent is first incorporated into the outer wall without simultaneous complete decomposition and / or evaporation. Thereafter, a decomposition and / or evaporation takes place with the incorporated into the outer wall substance with which the pores are generated in the outer wall. Preferably, therefore, the second energy input has a lower energy density than the third energy input.

In one embodiment of the invention, the third energy input is introduced in a spatially limited area which is smaller than a spatially limited area in which the second energy input is introduced. The third energy input is thus introduced locally limited than the second energy input, for example, based on an area of the outer wall. With regard to the total energy, the second energy input in this case can then also be greater than the third energy input overall, even in the event that the second energy input has a lower energy density than the third energy input.

The foaming agent contains as foaming reagent, for example, one or more of the following chemicals: AX, A2Y, BX2, or BY, where A is a monovalent cation, preferably an alkali metal, B is a divalent cation, preferably an alkaline earth metal, X is a monovalent anion, preferably nitrate, and Y is a divalent anion, preferably sulfate or carbonate.

Of course, the above-mentioned generation of micro and / or nanodefects can also be combined with this development. Such a combination of the two methods may e.g. be applied only in a certain predetermined range of the electrochemical transfer. Depending on the configuration of the electrochemical transfer, it may also comprise a first region which has pores produced by the generation of micro and / or nano-defects, and a second region which has pores produced by the decomposition and / or evaporation of the incorporated foaming agent.

In one embodiment of the method according to the invention, the first, the second and / or the third energy input is introduced by means of a single laser.

In a further embodiment, the first, second and / or third energy input is introduced by means of at least two lasers.

In a preferred development of the invention, the pores produced in the outer wall are opened and / or enlarged by means of a chemical and / or mechanical removal method following the production of the pores. The chemical and / or mechanical removal method may be, for example, a grinding or etching. By opening pores, e.g. those of the pores, which are present as initially closed pores in the production, are additionally opened, thereby enlarging the open-pore region of the electrochemical transfer, whereby the open-pore region is e.g. assumes a predetermined extent and / or an e.g. predetermined pore density is achieved. Alternatively or additionally, by enlarging pores, it is achieved that these are e.g. have predetermined pore size.

In a further development of the invention, open pores having a pore size of less than 100 micrometers, in particular less than 50 micrometers, are produced in the outer wall. The pore size is referred to in this application, the diameter of the pores.

The solution according to the invention also relates to a housing for an electrochemical reference half cell wherein the housing has at least one chamber for receiving an electrolyte, wherein in an outer wall of the chamber, an electrochemical transfer is arranged, by means of which an electrolytic contact between an arranged in the chamber electrolyte and an outside the chamber can be arranged disposable medium. The housing according to the invention is characterized in that for at least one chamber or at least one of the chambers, the outer wall made of a material is integral and the electrochemical transfer in the outer wall is generated by means of at least one introduced into the outer wall energy input, wherein by the energy input in the area the electrochemical transfer pores are introduced into the material of the outer wall.

In the case of the chamber with the one-piece housing wall, the diaphragm is thus advantageously integrated directly into the outer wall and is itself part of the one-piece outer wall of the chamber. The chamber with the one-piece outer wall can, as mentioned above, still have an opening through which a reference discharge element can be introduced and an electrolyte can be introduced. The opening is then closable with the above-mentioned polymer seal.

In a preferred embodiment of the housing according to the invention, the electrochemical transfer in the one-piece outer wall comprises an open-pore region. The open-pore region of the electrochemical transfer is obtained by means of the process according to the invention.

In a further embodiment of the housing according to the invention, the material of the chamber is essentially a glass.

In a further embodiment of the housing according to the invention, the material of the chamber is essentially a Kunstsoff. In particular, it is a thermoplastic or a thermosetting plastic. The plastic may be, for example, a polyetherketone (PEK), in particular a polyetheretherketone (PEEK), which is suitable as a material for the housing due to its high chemical resistance and excellent electrical insulating properties.

In a further development of the housing according to the invention, the chamber and / or the housing are / is at least partially cylindrical.

In a preferred embodiment of this development, the pores are arranged substantially uniformly around a cylindrical end region of the chamber, in particular an end region facing away from the opening of the chamber.

As a result, the pores are arranged uniformly around an end region of the chamber facing the measuring medium, for example along an annular cylindrical section in the end region. By means of the uniformly distributed pores, the electrolytic contact between a medium which can be arranged outside the chamber and surrounding the chamber and an electrolyte which can be arranged in the chamber is produced from all sides of the chamber essentially to the same extent.

In a further development, the pores have a minimum pore density of at least 8 × 10 ^-2 / mm. In particular, the pores have a maximum pore density of at most 10 ⁴ / mm. For the purposes of this application, pore density is the mean number of pores along a cutting line.

• - ein erfindungsgemäßes Gehäuse;
• - ein in der Kammer angeordnetes Bezugs-Ableitelement, welches elektrisch leitend mit einer außerhalb der Kammer angeordneten elektrischen Kontaktstelle verbunden ist; und
• - zumindest einen Elektrolyten, der innerhalb der Kammer angeordnet ist.

The invention further relates to an electrochemical sensor having a reference electrochemical half cell, the reference electrochemical half cell comprising:

• - An inventive housing;
• - A arranged in the chamber reference-Ableitelement which is electrically connected to an outside of the chamber arranged electrical contact point; and
• - At least one electrolyte which is disposed within the chamber.

If the electrochemical sensor is brought into contact with a measuring medium in a measuring operation, the electrolyte arranged inside the chamber is in electrochemical contact with the measuring medium via the electrochemical transfer.

In the simplest case, the electrolyte is a reference electrolyte, in which, as described above, the reference diverter element is immersed.

Furthermore, the use of so-called bridge electrolytes, which are in electrochemical contact with the measuring medium via an electrochemical transfer of a first chamber, is known from the prior art. In this case, the reference diverter and the reference electrolyte are disposed in a second chamber, the second chamber again being disposed within the first chamber and in electrolytic contact with the first chamber. In particular, the reference electrolyte is via an electrochemical transfer of the second chamber in electrolytic contact with the bridge electrolyte. In this case, for the electrochemical sensor with the housing according to the invention for at least one of the two chambers, the electrochemical, for example, the first chamber, such that the outer wall of the chamber is made of a material of the chamber and the electrochemical transfer in the outer wall of the chamber by means of generated in the outer wall energy input is generated.

In one embodiment of the electrochemical sensor, the latter has an electrochemical measuring half cell with a potential-forming element and a diverting element, which is electrically conductively connected to the electrical contact point, and a control / evaluation unit which is designed for this purpose on the basis of the reference half cell and the at least to determine a measured variable of a measuring medium which is in contact with the electrochemical sensor, electrical signals generated by a measuring half-cell. In this embodiment, the electrochemical sensor is e.g. to an ion-selective electrode mentioned above.

In a further refinement of the electrochemical sensor, the latter has at least one semiconductor-insulator layer stack, which is electrically conductively connected to the electrical contact point, and a control / evaluation unit designed for this purpose on the basis of the reference half-cell and the at least one semiconductor Insulator layer stack generated electrical signals to determine a measure of a standing in contact with the electrochemical sensor measuring medium.

In this embodiment, the electrochemical sensor as an analyte-sensitive component thus comprises the semiconductor-insulator layer stack mentioned in the introduction, which is used e.g. in the ISFET sensor or as an EIS structure with capacitive evaluation.

The control / evaluation unit of these embodiments is designed as an electrical circuit which is designed for the control and / or evaluation of the electrochemical sensor. The signal generated by the contact point is transmitted to the control / evaluation unit. This happens, for example, by the contact point is connected to the control / evaluation unit via electrical paths.

• 1a,b,c: Verschiedene Ausgestaltungen des erfindungsgemäßen Verfahrens;
• 2: Eine Ausgestaltung einer Bezugshalbzelle mit dem erfindungsgemäßen Gehäuse;
• 3: Eine erste Ausgestaltung eines elektrochemischen Sensors mit einer Bezugshalbzelle mit einem erfindungsgemäßen Gehäuse;
• 4: Eine zweite Ausgestaltung eines elektrochemischen Sensors mit einer Bezugshalbzelle mit einem erfindungsgemäßen Gehäuse;
• 5: Eine dritte Ausgestaltung eines elektrochemischen Sensors mit einer Bezugshalbzelle mit einem erfindungsgemäßen Gehäuse.

The invention will be explained in more detail with reference to the following, not to scale figures, wherein like reference numerals designate like features. If it requires the clarity or it appears otherwise useful, is omitted reference numerals already mentioned in subsequent figures. It shows:

• 1a, b , c: Various embodiments of the method according to the invention;
• 2 : An embodiment of a reference half cell with the housing according to the invention;
• 3 A first embodiment of an electrochemical sensor having a reference half cell with a housing according to the invention;
• 4 A second embodiment of an electrochemical sensor having a reference half cell with a housing according to the invention;
• 5 A third embodiment of an electrochemical sensor with a reference half cell with a housing according to the invention.

In 1a, b , c are schematically different embodiments of the inventive method for producing the housing 3 shown. At the chamber 2a it is a substantially cylindrical chamber, wherein the sake of clarity, each only a sectional view of a section of the outer wall 4 the cylindrical chamber 2a is shown. The inventive method is in an end region EB the chamber 2a the electrochemical transfer 5a brought in.

In a first embodiment of the method, 1a , is done by means of a first laser L1 a first energy input ΔE1 in the outer wall 4 brought in. Here are in a laser deep engraving microdefects MD produced, in particular microcracks and micropores. By means of the laser L1 is the first energy input ΔE1 very precisely dosed and very precise in the end area EB the outer wall 4 recoverable. This will make the pores 6 in a defined or predetermined, the electrochemical transfer 5a forming end portion EB the outer wall 4 generated.

The by means of the laser L1 generated pores 6 are then additionally opened and enlarged in an etching process. This will be in the end area EB the chamber 2a the open-pore structure in the one-piece outer wall 4 with pores 6 of a pore size smaller than 50 μm (microns). The pores 6 are substantially uniform over a cylindrical portion of the cylindrical chamber 2a arranged distributed.

The open-pore structure becomes an electrochemical transfer 5 formed in the outer wall 4 is integrated so that the transition from the electrochemical transfer 5 to the adjacent area of the outer wall 4 is essentially seamless

In a second embodiment of the method, 1b , will be in the end area EB a foaming agent 7 having substance on a surface of the outer wall 4 applied, here the outwardly facing surface of the outer wall 4 , Of course, it is also possible in the context of the invention, the foaming agent 7 on both surfaces of the outer wall 4 applied. The foaming agent 7 contains at least one of the following chemicals: AX, A2Y, BX2, or BY, where A is a monovalent cation, preferably an alkali metal, B is a divalent cation, preferably an alkaline earth metal, X is a monovalent anion, preferably nitrate, and Y is a divalent anion Sulfate or carbonate.

The foaming agent is used in a first process step ( 1b , top field) in the outer wall 4 by means of a second energy input introduced into the outer wall ΔE2 incorporated. This is done in 1b a first laser L1 used. Of course, in the context of the invention, other or alternative methods for introducing the second energy input ΔE2 possible with which the substance and the material of the outer wall in the end region EB are melted and mixed with the likewise melted substance, including, for example, a purely thermal process.

The second energy input ΔE2 is doing so on the outer wall 4 , the substance and the foaming agent 7 agreed that during the incorporation of the foaming agent 7 essentially no or at least no complete decomposition and / or evaporation of the foaming agent 7 takes place. This is the foaming agent 7 as at least partially unfoamed and / or non-decomposed and in the outer wall 4 incorporated before.

In a second step, 1b , middle field, is then followed by a third energy input ΔE3 in the outer wall 4 incorporated foaming agent 7 at least partially decomposed and / or evaporated. The third energy input ΔE3 comes with a second laser L2 brought in. In the decomposition and / or evaporation of the foaming agent 7 For example, in the context of decomposition and / or evaporation in the outer wall 4 gas bubbles 19 formed, from in the decomposition and / or evaporation forming gases such as CO ₂ , NO _x and / or SO ₂ / SO ₃ . By means of the laser L2 is third energy input ΔE3 very precisely dosed and very precise einbrembar, so that only in the end area EB the gas bubbles 19 arise.

By means of the gas bubbles 19 become the pores 6 generated, see 1b bottom panel showing the open-pore area in the end area EB and thus the electrochemical transfer 5 the chamber 2a form. Similar to the method 1a can here then still another processing step of the outer wall 4 take place, in which by a mechanical removal method, the thickness of the outer wall is reduced and / or by a chemical removal method, an additional opening of partially or completely closed pores 6 he follows.

Of course, the in 1a and 1b also be combined, this is in 1c shown. Here are a first portion of the pores 6 the electrochemical transfer 5 through the in 1a shown method and a second portion of the pores 6 the electrochemical transfer 5 through the in 1b obtained shown method. In principle, there are no restrictions on the order of introduction of the energy inputs ΔE1 . ΔE2 . ΔE3 , In the context of the invention, it is also possible, only a single laser L1 for introducing the energy entries ΔE1 . ΔE2 . ΔE3 to use.

2 shows in a longitudinal sectional view of an embodiment of a reference electrochemical half-cell 1 with the housing according to the invention 3 with a cylindrical chamber 2a ,

In the chamber 2a is a reference diverting element 10 introduced, which by a the end area EB opposite opening 8th protrudes. The opening 8th the chamber 2a is through a polymer gasket 20 sealed liquid-tight. The reference diverter 10 is formed in the present example of a silver wire having a silver chloride layer in its front end portion.

In the chamber 2a the reference half-cell 1 is an electrolyte thickened by the addition of a polymer and containing a given halide concentration 12a , Here a reference electrolyte, containing, with reference diverter 10 is contacted. The chamber 2a has a one-piece outer wall 4 with the electrochemical transfer 5a in one end area EB the chamber 2a on. The electrochemical transfer 5a is by means of the circumference of the cylindrical chamber 2a in the end area EB evenly distributed pores 6 formed with a pore size of less than 50μm. The pores 6 have a pore density between 8 × 10 ^{-2 and} 10 ⁴ / mm, based on the cylindrical circumference of the cylindrical portion. The electrochemical transfer 5a is designed to electrolytic contact between the electrolyte 12a and one outside the chamber 2a can be prepared medium, for example, with a medium 17 (not shown here), in which the reference half cell dips with its end.

Through the one-piece outer wall 4 the chamber 2a is the chamber 2a of the housing 3 the reference half-cell 1 particularly stable against chemical and / or mechanical stress, which, for example, by the contact of the end region EB the chamber 2a with the measuring medium 17 and / or caused by the autoclaving mentioned above. In addition, the uniform distribution of the pores is advantageous 6 , As well as their size, with the production of the electrolytic contact with simultaneous low leakage of the electrolyte 12a out of the chamber 2a via the electrochemical transfer 5a is ensured.

3 shows a longitudinal sectional view of an electrochemical sensor 9 , The electrochemical sensor 9 is designed as a rod-shaped probe whose front end region EB for immersion in a measuring medium 17 is determined. In the present example, the electrochemical sensor is 9 around a potentiometric sensor.

The measuring half cell 13 of the electrochemical sensor 9 has an analyte-sensitive membrane 15 , in the present example an ion-selective membrane on. This closes the inner tube of the electrochemical sensor 9 at his the measuring medium 17 facing end region. In the housing formed by an inner tube of the measuring half-cell 13 is one as an inner electrolyte 21 designated, further electrolyte absorbed. In the present example, the inner electrolyte 21 an aqueous solution containing a predetermined concentration of the analyte, its concentration in the measuring medium 17 by means of the electrochemical sensor 9 should be monitored. In the inner electrolyte 21 a drain element emerges 16 one that has a contact point 11 outside the housing of the measuring half cell 13 connected to a measuring circuit. At his from the analyte-sensitive membrane 15 opposite, rear end is the inner tube by a polymer seal 20 sealed liquid-tight.

The reference half cell 1 comprises a cylindrical housing of the measuring half cell 13 concentric surrounding housing 3 with a chamber 2a , Both the measuring half cell 13 as well as the reference half cell 1 consist of glass.

The reference half cell 1 is designed as a silver / silver chloride electrode. It goes without saying that the reference half cell also in shape other reference electrodes of the second type can be realized in a very analogous manner. The reference electrolyte 12a comprises a specific concentration of a chloride salt, in the present case is specifically a 3 molar potassium chloride solution. In the reference electrolyte 12a a reference diverter emerges 10 a, which is formed in the present example as a silver wire having at least in its end a silver chloride layer.

About in the outer wall of the chamber 2a arranged electrochemical transfer 5a with the open-pore structure in the end area EB is the reference electrolyte 12a with the outside of the chamber 2 arranged measuring medium 17 electrolytically in contact.

For carrying out a measurement of an analyte concentration in a measuring medium 17 becomes the front end portion of the electrochemical sensor 9 so far in the medium 17 immersed that both the membrane 15 as well as the electrochemical transfer 5a in contact with the measuring medium 17 stand.

A control / evaluation unit comprising a measuring circuit 14 is designed to be one in the contact point 11 detected potential difference between the diverting element 16 the measuring half cell 13 and the reference diverter 10 the reference half-cell 1 to capture, and output a dependent measurement signal to a higher-level unit.

The between the diverting element 16 and the reference diverter 10 detectable potential difference depends on the analyte concentration in the medium 17 so that one from the control / evaluation unit 14 output measured signal represents the analyte concentration or a dependent of the analyte concentration measurement.

4 shows a longitudinal section illustration of an embodiment of an electrochemical sensor 9 , whose reference half-cell 1 a formed as a bridge electrolyte electrolyte 12a includes.

The measuring half cell 13 is essentially the same design as the measuring half-cell 13 of in 3 represented electrochemical sensor 9 , The reference half cell 1 The pH sensor includes a first chamber concentrically surrounding the inner tube through the inner tube of the measuring half-cell 2a within which a second chamber 2 B is arranged. The second chamber 2 B has at its front end an electrochemical transfer 5b on. The second chamber 2 B contains a liquid reference electrolyte 12b containing a predetermined chloride concentration and into which a diverting element 10 For example, a silver wire coated with silver chloride is immersed. The reference electrolyte 12b may be thickened by a polymer, but is still advantageously flowable. The second chamber 2 B is at her the electrochemical transfer 5b opposite end with a polymer seal 20 locked. Between the polymer seal 20 and the reference electrolyte 12 a gas space is provided, the compensation of thermally induced volume changes of the reference electrolyte 12b serves. The diverting element 10 is through the polymer gasket 20 passed through and over the contact point 11 with the control / evaluation unit 14 electrically connected.

As in the case of the 3 described embodiment is the control / evaluation unit 14 configured to one of the potential difference between the diverting element 10 the reference half-cell 1 and the diverting element 16 the measuring half cell 13 to generate dependent measurement signal and output to a higher-level unit.

The through the outer wall 4 the first chamber 2a and the inner tube formed first chamber 2a contains an electrolyte designed as bridge electrolyte 12a who is the second chamber 2 B surrounds, so that the electrolyte formed as a reference electrolyte 12b via the electrochemical transfer 5a in the outer wall 4 the second chamber 2 B with the electrolyte formed as bridge electrolyte 12a is in electrolytic contact. In the outer wall of the first chamber 2a is another electrochemical transfer 5b arranged over which the electrolyte formed as a bridge electrolyte 12a with one outside the case 3 arranged measuring medium 17 is in electrolytic contact. In the case of such a multi-chamber construction 2a 2b can be reference electrolyte 12b and bridge electrolyte 12a be different; as are the two electrochemical transfers 5a (between first chamber 2a and measuring medium 17 ) and 5b (Between the electrolyte formed as a reference electrolyte 12b to the electrolyte formed as bridge electrolyte 12a ) differently.

In the present example, only for the first chamber 2a the outer wall 4 such that the existing of a material outer wall 4 the chamber 2a is integral and the electrochemical transfer 5b in the outer wall 4 the chamber 2a by means of the in the outer wall 4 introduced energy input ΔE1 . ΔE2 . ΔE3 is generated. The outer wall 4 the first chamber 2a namely, in particular, is exposed to the chemical and / or mechanical stresses mentioned at the outset. Of course, it is within the scope of the invention also possible, both chambers 2a 2b with such a one-piece outer wall according to the invention 4 and the integrated therein electrochemical transfer 5a , 5b.

4 shows a longitudinal section illustration of an embodiment of an electrochemical sensor 9 , for measuring a pH of a medium 17 , The electrochemical sensor shown here 9 includes a reference half-cell 1 which are essentially like in 2 is shown, so that for the features of the reference half cell 1 on the already in 2 referenced features. The housing 3 Reference half-cell 1 has a chamber 2a with a one-piece outer wall 4 and the integrated therein electrochemical transfer 5a on, and consists of a plastic, preferably PEEK. Peek is suitable as the material for the housing due to its high chemical resistance and excellent electrical insulating properties 3 suitable.

The electrochemical sensor 9 has a pH-sensitive semiconductor insulator layer stack 18 which may comprise an insulator coating comprising Ta ₂ O ₅ and which forms a transistor gate of an ISFET. The carrier density in the semiconductor channel between the source and drain of the ISFET depends on the pH of the semiconductor insulator layer stack 18 in contact with the measuring medium 17 from. The field effect through the charges on or in the insulator coating controls the gate of the ISFET, impressing a constant current between source and drain. From a control voltage required for the constant current is combined with the potential of the reference half cell 1 in the electrical contact point 11 formed a measuring voltage. The control / evaluation unit 14 is configured to detect the measurement voltage and output a measurement signal dependent thereon for the pH value.

Although the invention is described with reference to a pH sensor with a pH-sensitive ISFET, the invention is, of course, transferable to sensors with other sensor elements, in particular sensor elements comprising ISFETs or ChemFETs or other EIS structures. By using other semiconductor insulator layer stacks 18 For example, EIS sensor elements can be formed which are correspondingly sensitive to other ions. By immobilizing suitable detector structures, which may include, for example, enzymes, on the EIS structure, it is also possible by means of such an electrochemical sensor 9 Concentrations of nonionic substances, such as glucose or penicillin.

LIST OF REFERENCE NUMBERS

1

electrochemical reference half-cell

2a, 2b

chamber

3

casing

4

outer wall

5, 5a, 5b

electrochemical transfer

6

pore

7

foaming

8th

opening

9

electrochemical sensor

10

Reference diverting

11

contact point

12a, 12b

electrolyte

13

electrochemical measuring half cell

14

Control / evaluation unit

15

potential-forming element

16

diverter

17

measuring medium

18

Semiconductor-insulator-layer stack

19

gas bubbles

20

Polymersealing

21

internal electrolyte

ΔE1, ΔE2, ΔE3

energy input

L1, L2, ..

laser

MD, ND

Microdefects, nanodefects

EB

end

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19857953 A1 [0005]

Claims (17)

A method for producing a housing (3) for a reference electrochemical half-cell (1), wherein the housing (3) at least one chamber (2a, 2b) for receiving an electrolyte (12a, 12b), wherein in an outer wall (4) of the chamber (2a, 2b) an electrochemical transfer (5,5a, 5b) is arranged, by means of which an electrolytic contact between an in the chamber (2a, 2b) can be arranged in the electrolyte (12a, 12b) and one outside the chamber (2a, 2b) can be produced anordenbaren medium; characterized in that for at least one chamber (2a; 2b) or at least one of the chambers (2a; 2b) the outer wall (4) made of a material is integral and the electrochemical transfer (5,5a, 5b) in the outer wall (4 ) is generated by means of at least one energy input (ΔE1, ΔE2, ΔE3) introduced into the outer wall (4), whereby pores (6) are formed by the energy input (ΔE1, ΔE2, ΔE3) in the region of the electrochemical transfer (5, 5a, 5b). be introduced into the material of the outer wall (4). Method according to Claim 1 wherein the at least one energy input (ΔE1; ΔE2; ΔE3) is introduced into the outer wall (4) of the chamber (2a, 2b) by means of at least one laser (L1; L2; ..). Method according to at least one of the preceding claims, wherein the outer wall (4) is selectively changed by means of at least one first energy input (ΔE1) of the at least one laser (L1; L2; ..) to at least one micro-defect and / or nano-defect (MD, ND) , and wherein the pores (6) are produced in the outer wall (4) by means of the micro-defect and / or nano-defect (MD, ND). Method according to at least one of the preceding claims, wherein the outer wall (4) by means of the at least one laser (L1; L2; ..) is in each case selectively changed to a multiplicity of microdefects and / or nanodefects (MD, ND), and wherein Microdefects and / or nanodefects (MD, ND), the pores (6) in the outer wall (4) are generated. Method according to at least one of the preceding claims, wherein a substance having a foaming agent (7) is applied to an inner and / or outer surface of the outer wall (4), wherein the foaming agent (7) is at least partially worked into the outer wall (4) by means of a second energy input (ΔE1), and wherein the foaming agent (7) is at least partially decomposed and / or vaporized in the outer wall (4) by means of a third energy input (ΔE3) different from the second energy input (ΔE2), whereby gas bubbles (19) formed during the decomposition and / or evaporation the pores (6) are produced in the outer wall (4). Method according to at least one of the preceding claims, wherein the first energy input (ΔE1), the second energy input (ΔE2) and / or the third energy input (ΔE3) are introduced by means of a single laser (L1), or wherein the first energy input (ΔE1), the second energy input (ΔE2) and / or the third energy input (ΔE3) by means of at least two lasers (L1, L2; ..) are introduced. Method according to at least one of the preceding claims, wherein the pores (6) produced in the outer wall (4) are opened and / or enlarged by means of a chemical and / or mechanical removal method following the production of the pores (6). Method according to at least one of the preceding claims, wherein open pores (6) having a pore size smaller than 100 micrometers, in particular smaller than 50 micrometers, are produced in the outer wall (4). Housing (3) for a reference electrochemical half-cell (1), wherein the housing (3) at least one chamber (2a, 2b) for receiving an electrolyte, wherein in an outer wall (4) of the chamber (2a, 2b) an electrochemical transfer ( 5, 5a, 5b) by means of which an electrolytic contact between an electrolyte (12a, 12b) which can be arranged in the chamber (2a, 2b) and a medium which can be arranged outside the chamber (2a, 2b) can be produced; characterized in that for at least one chamber (2a, 2b) or at least one of the chambers (2a, 2b) the material consisting of a material outer wall (4) is in one piece, and the electrochemical transfer (5,5a, 5b) in the outer wall ( 4) by means of at least one introduced into the outer wall (4) energy input, wherein by the energy input in the region of the electrochemical transfer (5,5a, 5b) pores (6) are introduced into the material of the outer wall (4). Housing (3) after Claim 9 wherein the electrochemical transfer (5, 5a, 5b) in the one-piece outer wall (4) comprises an open-pore region. Housing (3) after Claim 9 or 10 wherein the material of the chamber (2a, 2b) is essentially a glass. Housing (3) after Claim 9 or 10 , wherein the material of the chamber (2a, 2b) is substantially a, in particular thermoplastic or thermosetting, plastic. Housing (3) according to at least one of Claims 9 to 12 , wherein the chamber (2a, 2b) and / or the housing (3) is at least partially cylindrical / is. Housing (3) after Claim 13 , wherein the pores (6) are arranged essentially uniformly around a cylindrical end region (EB), in particular an end region (EB), which faces away from an opening (8) of the chamber (2a, 2b), of the chamber (2a, 2b). Electrochemical sensor (9) with a reference electrochemical half-cell (1), wherein the reference electrochemical half-cell (1) comprises: - a housing (3) according to at least one of Claims 9 to 14 ; - A in the chamber (2a, 2b) arranged reference-Ableitelement (10), which is electrically conductively connected to an outside of the chamber (2a, 2b) arranged electrical contact point (11); and - at least one electrolyte (12a, 12b) disposed within the chamber (2a, 2b). Electrochemical sensor (9) after Claim 15 , comprising at least one electrochemical measuring half-cell (13) with a potential-forming element (15) and with a diverting element (16), which is electrically conductively connected to the electrical contact point (11), and a control / evaluation unit (14) designed for this purpose is to determine, based on the reference half cell (1) and the at least one measuring half cell (13) generated electrical signals, a measured variable of a standing with the electrochemical sensor (9) in contact with the measured medium (17). Electrochemical sensor (9) after Claim 15 comprising at least one semiconductor-insulator layer stack (18) which is electrically conductively connected to the electrical contact point (11), and a control / evaluation unit (14) designed for this purpose from the reference half-cell (1) and the electrical signals generated at least one semiconductor-insulator layer stack (18) to determine a measured variable of a measuring medium (17) in contact with the electrochemical sensor (9).

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