Sensor, and device for sensor comprising gel electrolyte

Abstract

To provide a sensor with an exchangeable membrane and electrolyte, which can be assembled in any desired orientation, and devices for such a sensor.SOLUTION: A sensor (2) comprises an electrolyte provided between a reinforced membrane (3) and a sensor shaft (21). The sensor shaft (21) comprises electrodes (212). A device (1) for such a sensor comprises a predisposed gel electrolyte (4).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001]

[0001] Sensors can be used to measure species in process media. Such sensors can be electrochemical sensors, equipped with electrodes that generate an electrical signal that depends on the species being measured. The electrical signal can be a voltage or a current. If the target species is a gas, the electrodes are usually separated from the process medium by a membrane, which allows the species being measured to diffuse through the membrane. For use in the process and bioprocessing industries, the process medium is a liquid and the membrane is reinforced to make it stable for this use.

[0002]

[0002] Such sensors usually require an electrolyte between the membrane and the electrodes. The electrodes are usually arranged in the sensor shaft. Depending on the type of sensor, the sensor shaft can comprise a different number of electrodes, more than one. The sensor shaft can comprise metal electrodes on the outside of the sensor shaft or on the inside of the sensor shaft, if the shaft provides means for ion conduction from and to the metal electrodes. The metal electrodes that end on the inside of the sensor shaft can be at least partially surrounded by an internal electrolyte for this purpose.

[0003]

[0003] The membrane, which is in contact with the process medium during use of the sensor, usually needs to be replaced more frequently than the sensor shaft. Similarly, the electrolyte between the membrane and the sensor shaft needs to be replaced more frequently than the sensor shaft to ensure reliable measurement results. Therefore, sensors often comprise a device distinct from the sensor shaft, which comprises the electrolyte. [Background technology]

[0004]

[0004] An example of a sensor for measuring species in a process medium is Mettler Toledo's InPro 5000i: it comprises an internal body pH electrode and a membrane body. In this description, the internal body pH electrode is one embodiment of the sensor shaft. The membrane body comprises a PTFE-coated CO2-permeable silicone membrane and is filled with a liquid electrolyte prior to operation. In this description, the membrane body is a support cap.

[0005]

[0005] This sensor can withstand the environments of the process and bioprocessing industries, but requires that it be assembled in a near vertical orientation and otherwise used at an angle of at least 15° to the horizontal; electrolyte will leak out of the tip of the sensor shaft, leaving an air-filled gap between the membrane and the sensor shaft, which results in poor quality measurements.

[0006]

[0006] It is known, for example from US 20 190 011 393 (A1) or EP 0 740 149 (B1), to thicken the electrolyte. In some documents such a thickened electrolyte is named "gel", but it is clear from the context that the electrolyte is still fluid, as is the case in US 3 666 650, where an aqueous solution is given as an example of a "gel". Such a thickened electrolyte may be useful for different reasons disclosed in the cited documents, but does not give the user wider freedom to choose the orientation in which the sensor may be used.

[0007] Gel electrolytes are further known for use in solid state sensors, such as those disclosed in Japanese Patent Publication No. 2 512 843 (B2) and references therein. Such sensors differ significantly from sensors with a sensor shaft with electrodes in the amount of electrolyte, their shape, and their field of use. In particular, it is generally not possible for the user to replace the membrane and electrolyte of the sensor. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent Application Publication No. 20190011393(A1) [Patent Document 2] European Patent No. 0740149(B1) [Patent Document 3] U.S. Patent No. 3,666,650 [Patent Document 4] Japanese Patent Publication No. 2512843 (B2) Summary of the Invention [Problem to be solved by the invention]

[0009]

[0008] Therefore, the technical problem to be solved is to provide a sensor and a device for such a sensor having a replaceable membrane and electrolyte that can be assembled in any desired orientation. [Means for solving the problem]

[0010]

[0009] This is achieved by a device and a sensor according to the independent claims.

[0010] A device for a sensor according to the invention includes a pre-disposed gel electrolyte. A sensor using such a device includes an electrolyte between a reinforced membrane and a sensor shaft. The sensor shaft is provided with an electrode. Such a sensor is preferably suitable for measuring a species in a process medium.

[0011] The electrolyte between the reinforcement membrane and the sensor shaft is provided by the device in the form of a pre-disposed gel.

[0012]

[0012] The gel cannot flow in the sense of the present invention: if an increasing pressure is applied locally, the gel will deform and eventually break. A first part of the gel separated from a second part of the gel will remain a separate part even if the first and second parts are placed close to each other. These properties preferably apply for the temperature range to which the sensor or device may be exposed during storage and normal use. Preferably, the gel cannot flow in the sense of the present invention at temperatures below 40°C, most preferably the gel cannot flow at temperatures below 90°C at atmospheric pressure or below. Preferably, if a gel according to the present invention liquefies above a threshold temperature, it will gel again when the gel is cooled below this threshold temperature.

[0013]

[0013] Due to its non-flowing behavior, the gel electrolyte according to the invention remains in the desired position between the reinforced membrane and the sensor shaft, independent of the orientation of the sensor. Furthermore, the gel electrolyte makes it easier to operate and ship devices with pre-disposed electrolyte: if the electrolyte were to be able to flow, the correct orientation of the device would have to be guaranteed from production to installation. Since this is usually not feasible, in the prior art the user is instructed to fill the electrolyte shipped in a bottle into the volume between the membrane and the sensor shaft himself. This makes conventional assembly a challenge. Furthermore, the use of a device with pre-disposed gel electrolyte makes it possible to assemble the sensor in all orientations.

[0014]

[0014] Thanks to the use of the reinforced membrane, it has been found that by pushing the sensor shaft in the direction of the reinforced membrane with the gel electrolyte disposed between the sensor shaft and the reinforced membrane, the gel electrolyte acquires a desired shape without weakening or deforming the membrane in a manner that would reduce the membrane's life or sensor sensitivity.

[0015] In a preferred embodiment, the gel electrolyte is a non-fluid colloidal or polymeric network that is extended throughout its volume by a fluid having the desired electrolyte properties. This has the advantage that the user can determine the appropriate composition of the electrolyte for the sensor in question that has an electrolyte that is liquid. This makes the experiment faster.

[0016]

[0016] Preferably, the gel electrolyte exhibits shear thinning and / or thixotropic behaviour. The viscosity of a shear thinning gel decreases when a shear stress is applied. A gel behaving thixotropically decreases its viscosity over the time during which a shear stress is applied. Squeezing the gel electrolyte between the reinforcing membrane and the sensor shaft during insertion of the sensor shaft causes the application of a shear stress. This decrease in viscosity during insertion allows the gel electrolyte to come into intimate contact with the membrane and the sensor shaft and to adapt its shape accordingly. This improves the sensitivity of the sensor and its lifetime, since the pressure on the reinforcing membrane is lower compared to embodiments having gels whose viscosity is independent or increases with shear stress.

[0017] In one embodiment, the device is stable to sterilization procedures. The sterilization procedures can be one of the following: steam sterilization, autoclave, gamma radiation, x-ray, or electron beam sterilization. Stability to sterilization procedures is obtained by selecting a gelling agent that is stable to the desired sterilization procedure. Preferably, the gel electrolyte is made using a polysaccharide as the gelling agent, most preferably agarose, or by using an adsorbent-based or polymer-based gelling agent.

[0018]

[0018] Examples of polysaccharide gelling agents are agarose, cellulose, and their derivatives.

[0019]

[0019] Adsorption-based gelling agents are materials with a large specific surface area that store large volumes of liquid per mass unit by adsorption. Fumed silica and silica gel are examples of adsorption-based gelling agents.

[0020] Polyacrylamides, polyacryloylaminoethoxyethanols, and polyglycols are examples of polymer-based gelling agents.

[0021] In a set of experiments, it was found that the adsorbent-based gelling agents were stable to gamma irradiation, while the polymer-based and polysaccharide gelling agents were suitable for heat sterilization procedures.

[0022] It has further been found that among the polysaccharides, agarose in particular is a gelling agent which is stable to gamma sterilization.

[0023]

[0023] Gamma sterilization is the preferred method of sterilizing single-use bioreactors, bags, and bioprocessing equipment in which the device according to the invention forming the single-use sensor adapter can be installed. By pre-dispensing the device with a gel electrolyte produced with agarose as the gelling agent, the single-use bag can be sterilized together with the mounted single-use sensor adapter.

[0024]

[0024] Steam sterilization is a preferred method of sterilizing multi-use process industrial equipment. Therefore, a device according to the present invention having a gel electrolyte produced using polysaccharides or synthetic polymers as gelling agents is preferably used for inserting sensors into multi-use process industrial equipment.

[0025]

[0025] Furthermore, it was found that some gelling agents cause a change in the pH value of the gel during the sterilization procedure. If the sensor uses the Severinghaus measurement principle, this pH drift can be compensated for by a suitable calibration after the sterilization procedure. Preferably, however, a gelling agent is used that does not cause a change in the pH value when subjected to a given sterilization procedure. It was found that agarose is a polysaccharide gelling agent that does not significantly change the pH value of the gel when subjected to gamma sterilization. Preferably, the gelling agent is selected such that the sterilization procedure causes a change in the pH value of less than 0.5 pH units, most preferably less than 0.3 pH units. Agarose has this property in the case of gamma sterilization as well as in the case of steam sterilization. Therefore, agarose is preferably used for single-use adapters for Severinghaus sensors.

[0026]

[0026] A gelling agent is considered stable to sterilization methods if the gel before and after sterilization is essentially the same. In the case of gamma ray, x-ray, and electron beam sterilization, the gel remains a gel during the sterilization process, and therefore the orientation of the device during sterilization can be freely selected by the user.

[0027] During steam sterilization, the temperature can rise up to 140° C., i.e. above the threshold temperature of some of the gels according to the invention at which the gel liquefies. These gel-filled devices should be steam sterilized in an orientation that prevents leakage of the gel or be mounted on the sensor shaft such that the sensor provides at least a temporary closed volume that prevents undesired displacement of the liquefied gel during steam sterilization.

[0028] In a preferred embodiment, the gel electrolyte contains a buffer for the species to be measured. The pH value of the gel electrolyte thereby varies proportionally to the species to be measured that can diffuse through the implemented membrane. The sensor shaft forms a pH sensor. The reading of the sensor shaft is thereby an indication of the partial pressure of the species to be measured. The sensor using the device is thereby a Severinghaus sensor.

[0029] In a particularly preferred embodiment, the sensor using the device is a Severinghaus sensor that measures CO2, and therefore the gel electrolyte contains one or several bicarbonate-based pH buffers. In another particularly preferred embodiment, the sensor using the device measures NH3 and / or NH4 + The Severinghaus sensor measures pH, and the gel electrolyte therefore contains one or several ammonium salt-based pH buffers.

[0030] In another preferred embodiment, the sensor using the device is a Clark-type sensor that measures O2 and / or dissolved O2, and thus the gel electrolyte comprises an alkaline hydroxide-based high pH solution.

[0031] In a preferred embodiment, the device includes a support cap having an opening to allow insertion of the sensor shaft in preparation for use. The support cap holds a reinforced membrane that forms a barrier between the process medium and the sensor shaft that can be passed by species during use of the sensor. A gel electrolyte is pre-disposed in the support cap on the side of the reinforced membrane facing the opening.

[0032]

[0032] To assemble the sensor in use, the user only needs to insert the sensor shaft into the device. By doing so, the gel electrolyte is deformed to surround the sensitive area of ​​the sensor shaft while still in contact with the reinforced membrane. The pre-disposed gel electrolyte can be located directly on the reinforced membrane, or the pre-disposed gel electrolyte can be located at a certain distance to the membrane so that it moves to the reinforced membrane during insertion of the sensor shaft. Pre-disposing the gel electrolyte directly on the reinforced membrane has the advantage that the gelling can occur directly in the support cap. Pre-disposing the gel electrolyte at a certain distance to the membrane has the advantage that the gel electrolyte can be added to the support cap after gelling, which gives the manufacturer greater control over the gelling process.

[0033]

[0033] In a preferred embodiment, a spacer mesh is placed on top of the reinforcement membrane. The spacer mesh is preferably formed by a nylon mesh. The spacer mesh defines the minimum distance between the reinforcement membrane and the sensor shaft, thereby allowing for greater tolerances in the connection system between the support cap and the sensor shaft. The use of the spacer mesh further allows for control of the distance between the membrane and the sensor shaft in embodiments where a cap sleeve is used to press the support cap onto the sensor shaft.

[0034]

[0034] The dimensions of the support cap and the amount of pre-disposed gel electrolyte are arranged such that during use the gel electrolyte covers a required portion of the sensor shaft. Preferably, the amount of pre-disposed gel electrolyte is such that in the assembled sensor, the support cap is essentially filled up to the contact line between the sensor shaft and the support cap. The contact line is preferably a limit stop for the sensor shaft and / or a sealing structure of the support cap. Most preferably, the fill level of the gel electrolyte in the assembled sensor is greater than 90% of the maximum fill level defined by the contact line at room temperature.

[0035]

[0035] The support cap can be equipped with a window made of a flexible material that allows for some thermal expansion of the gel electrolyte. Such a window is preferably present in the support cap in the form of a membrane body. The membrane body is preferably connected to the sensor shaft with the aid of the support cap. Preferably, in the configuration for use, a retainer is arranged between the membrane body and the sensor shaft such that the volume filled by the gel electrolyte is essentially isolated from the surroundings. This prevents the gel electrolyte from drying out completely and increases the lifespan of the sensor. In addition to or instead of the retainer, the support cap can be equipped with a flexible O-ring-like sealing structure surrounding the opening. Preferably, this sealing structure is made of the same flexible material as the window. In the assembled sensor, the sealing structure fills the gap between the support cap and the sensor shaft, thereby defining a closed volume.

[0036]

[0036] Preferably, the amount of gel pre-disposed is such that the closed volume is essentially filled in the assembled sensor. When such a sensor is steam sterilized and heated in this procedure, the gel expands, thereby filling any remaining space in the closed volume and distending the flexible window. If the maximum temperature reached during steam sterilization exceeds the threshold at which the gel electrolyte liquefies, the closed volume ensures that the liquefied gel remains in the desired location, and when the temperature drops, the restoring force of the flexible window material presses the gelling liquefied gel against the sensor shaft. Thus, steam sterilization can occur in any orientation. The same mechanism operates if the sensor heats up to a temperature above the threshold for other reasons.

[0037]

[0037] In another embodiment, preferably the support cap, when it is a single-use sensor adapter, comprises two concentrically arranged cylindrical sections. The inner cylindrical section is closed by a reinforced membrane, which is preferably covered by a spacer mesh. The gel electrolyte is pre-disposed in this inner cylindrical section. The diameter of the inner cylindrical section is such that the sensor shaft can be inserted into the inner cylindrical section. Thereby, the gel electrolyte is displaced inside the inner cylindrical section so that the desired part of the sensor shaft is surrounded by the gel electrolyte. In one embodiment, preferably, rather than a retainer, in the assembled sensor there is a peripheral opening to the inner cylindrical section surrounding the sensor shaft, which allows the gel electrolyte to expand when heated. In another embodiment, the inner cylindrical section can be equipped with a flexible O-ring-like seal structure surrounding the opening. Preferably, this seal structure is made of an O-ring arranged in a peripheral recess near the top of the inner cylindrical section. In the assembled sensor, the seal structure fills the gap between the inner cylindrical section and the sensor shaft, thereby defining a closed volume. The amount of pre-disposed gel is such that the closed volume is essentially filled within the assembled sensor, which prevents complete drying of the gel electrolyte, thereby increasing the sensor's lifespan.

[0038]

[0038] In some embodiments, the internal cylindrical section can be equipped with a flexible window similar to that of the membrane body, but such a window is omitted in other cases: the single-use sensor adapter is most commonly sterilized by irradiation with gamma beam, x-rays, or electrons, and therefore does not experience large changes in temperature during its life. Therefore, a means of compensating for thermal expansion, such as a flexible window, can be omitted, resulting in an easier production process. However, providing a means of compensating for thermal expansion in the internal cylindrical section and the seal structure allows the single-use sensor adapter to be steam sterilized, or to be exposed to temperatures above the liquefaction threshold of the respective gel electrolyte for other reasons.

[0039] In the following, the orientation is described by the side with the membrane being "below" the side with the opening for inserting the sensor shaft. This description is purely intended to describe the relative positions of the different parts with respect to each other and is not intended to limit the orientation of the sensor or adapter during use or assembly.

[0040]

[0040] The outer cylindrical section surrounds the inner cylindrical section. The two cylindrical sections are connected in a fluid-tight manner at their lower ends. The upper end of the outer cylindrical section is higher than the upper end of the inner cylindrical section, and their connection is such that a hollow cylindrical volume is formed between them. This volume can hold excess gel electrolyte if required, but it is preferred that the pre-disposed amount of gel electrolyte and the height of the inner cylindrical section are such that leakage is unlikely, even at high temperatures that may occur during the sterilization process.

[0041]

[0041] The external shape of the outer cylindrical section is preferably such that it can be inserted into and connected to a standard port for single-use bags, such as, for example, a standard 1'' Eldon James port. Preferably, the internal shape of the outer cylindrical section comprises a peripheral shoulder in its lower part, on which the connecting part can be placed. The connecting part preferably comprises a peripheral external rim at its upper end, which corresponds to the shoulder of the outer cylindrical section. The connecting part preferably further comprises a shoulder on its inner surface, preferably close to its lower end. In this embodiment, the inner cylindrical section comprises a recess on its lower outer surface, which corresponds to the shoulder of the connecting part. The connecting part is preferably further equipped with a sealing means, such as an O-ring. In the assembled state, in this embodiment, the external rim of the connecting part is placed on the shoulder of the outer cylindrical section and the recess of the inner cylindrical section is placed on the shoulder of the connecting part. It is the connecting part that connects the inner and outer cylindrical sections in a fluid-tight manner.

[0042]

[0042] Such a modular construction of the single-use sensor adapter has the advantage that the production process can be quickly adapted to the changing needs of the user: the outer cylindrical section will usually remain the same for many types of sensors, while the inner cylindrical section can be adapted to the needs of the user by the choice of membrane and pre-disposed gel electrolyte. Since different sensors can have different sized sensor shafts, the diameter of the inner cylindrical section may differ, and such differences can be accommodated by the diameter of the connecting parts. Depending on the expected mechanical loads on the single-use sensor adapter, the inner and outer cylindrical sections and the connecting parts can be connected by press fit, by adhesive or by a screw connection.

[0043]

[0043] A single-use bag according to the present invention includes a single-use sensor adapter according to the present invention. The single-use bag is preferably sterilized.

[0044]

[0044] This single-use bag is particularly comfortable for the user, since the user only needs to insert the sensor shaft. The reinforced membrane of the single-use sensor adapter forms a sterilization barrier between the inside and outside of the bag. Thanks to the pre-disposed gel electrolyte, the bag can be manipulated and positioned without restrictions on the orientation of the single-use adapter. If the single-use bag is not yet sterilized, the user can sterilize it. Depending on the choice of sterilization method and the choice of pre-disposed gel electrolyte, the sterilization process can also be performed without restrictions on the orientation of the single-use adapter.

[0045]

[0045] Preferably, the single-use bag is sterilized by gamma irradiation and the gelling agent of the gel electrolyte is agarose.

[0046]

[0046] Most preferably, the gel electrolyte includes a bicarbonate pH buffer and the single-use bag's single-use sensor adapter includes a selectively CO2-permeable membrane that forms a sterility barrier as well as a portion of the sensor. By inserting the sensor shaft of the Severinghaus sensor into the single-use sensor adapter, the partial pressure of CO2 in the process medium maintained inside the single-use bag can be easily and reliably determined.

[0047] In a preferred embodiment, the reinforced membrane is in contact with the gel electrolyte on one side and is coated with a soluble coating on the other side. The soluble coating is preferably a polymer. The soluble coating dissolves on contact with a fluid. Preferably, the soluble coating dissolves on contact with a process medium.

[0048]

[0048] The pre-disposed gel electrolyte may dry out completely if it is in contact with the ambient air for a long time. In order to increase the shelf life, it is therefore desirable to put the gel electrolyte in a small volume that is essentially airtight. Since the sensor is supposed to measure gas, the reinforced membrane is semi-permeable to at least some gases. The gel electrolyte will therefore be exposed to at least some components of the ambient air if the membrane of the support cap is to be exposed to the ambient air. One way to avoid such direct contact is the application of a protective cap. However, a protective cap can only be used for the support cap membrane that is still accessible immediately before use. In the case of a single-use sensor adapter, this is usually not the case, since at this point the membrane is located inside the sterilized bag. In the case of other support caps, the lack of a protective cap increases the comfort for the user. Therefore, the use of a soluble coating is desirable: the soluble coating can be washed off by a rinsing fluid or by a process medium before the monitored process is started. Polymers, particularly polyvinylpyrrolidones such as povidone and crospovidone, which are soluble in water, various alcohols, and other solvents, have been found to be a suitable choice for such soluble coatings for most process media or rinse fluids based on any of these solvents.

[0049]

[0049] In a preferred embodiment, the removable protective part closes the opening of the support cap. This end of the opening of the support cap must be accessible, since the sensor shaft needs to be inserted into the support cap. The removable protective part, on the one hand, protects the gel electrolyte from drying out completely, and, on the other hand, stabilizes and protects the support cap itself during transport and handling. Depending on the assembly of the sensor in question, the removable protective part can be used to position the support cap in the desired location before the insertion of the sensor shaft into the support cap.

[0050] In a preferred embodiment, the device is a cartridge comprising a cylindrical support at least partially filled with a gel electrolyte, the inner circumference of the device and cylindrical support being such that at least a portion of the sensor shaft can penetrate completely into the cartridge along the longitudinal axis of the cylindrical support.

[0051]

[0051] In this embodiment, the cartridge is used to provide a pre-disposed gel electrolyte. In contrast to the support cap, the cartridge does not include a semi-permeable reinforcement membrane that will be in contact with the gel electrolyte during use of the sensor. Preferably, the cartridge is used with an empty support cap. It is the empty support cap that provides the reinforcement membrane. The empty support cap does not include pre-disposed gel electrolyte. In use, the cartridge is placed against the empty support cap such that insertion of the sensor shaft into the support cap moves the gel electrolyte away from the cylindrical support of the cartridge and to the reinforcement membrane, and the cartridge deforms such that the gel electrolyte is in direct contact with at least a part of the reinforcement membrane and the sensitive part of the sensor shaft, which must be covered by the electrolyte for reliable measurements.

[0052]

[0052] The dimensions of the empty support cap, the dimensions of the cylindrical support and the amount of pre-disposed gel electrolyte are such that the gel electrolyte covers the required portion of the sensor shaft during use. Preferably, the amount of pre-disposed gel electrolyte is such that the empty support cap is essentially filled up to the contact line between the sensor shaft and the empty support cap and / or the cylindrical support disposed in the empty support cap in the assembled sensor. The contact line is preferably a limit stop for the sealing structure of the sensor shaft and / or the empty support cap. Most preferably, the fill level of the gel electrolyte in the assembled sensor is greater than 90% of the maximum fill level defined by the contact line at room temperature.

[0053]

[0053] The cartridges facilitate the production of the device and the use of a modular system makes it possible to build the sensor of interest, with the advantages of simplified storage and adaptation to the user's needs.

[0054]

[0054] Preferably, the material and internal structure of the cylindrical support are such that the adhesion force between the gel electrolyte and the cylindrical support is less than the force required to tear the gel electrolyte. Thereby, the gel electrolyte can be completely extruded from the cylindrical support, which facilitates providing the desired amount of gel electrolyte. Most preferably, the adhesion force is less than the elastic limit of the gel electrolyte. In this case, the shape of the gel electrolyte is known, in its way between the cartridge and its shape in the assembled sensor. This facilitates the insertion of the gel electrolyte. Most preferably, the cylindrical support is made of a material that withstands different sterilization procedures, which are steam sterilization or autoclaving with temperatures above 140°C and pressures between 100 and 105 kPa, or sterilization by exposure to gamma or x-ray radiation or exposure to electron beam.

[0055]

[0055] Preferably, the cylindrical support is made of polyether ether ketone or PEEK: this material is resistant to different sterilization procedures and the adhesion forces between the tested gel electrolytes were low enough to allow the gel electrolyte to be pushed out of the cylindrical support completely and without permanent deformation.

[0056] In a preferred embodiment, both ends of the cylindrical support are covered by a removable and / or penetrable seal that can be broken by forcing the sensor shaft or gel electrolyte against the penetrable seal.

[0057]

[0057] Such a seal protects the gel electrolyte from drying out completely, thus increasing the shelf life. Moreover, the seal can prevent the gel electrolyte from unintentionally slipping off the cylindrical support. A penetrable seal is convenient for the user. Preferably, such a penetrable seal comprises a break line along which the seal is torn by the pressure of the sensor shaft or the gel electrolyte. Preferably, the penetrable seal is attached to the cylindrical support. Thereby, the remaining part for the penetrable seal is fixed to the cylindrical support during the use of the sensor, while the gel electrolyte is in contact with the reinforced membrane in the sensor shaft. A removable seal is more efficient when protecting the gel electrolyte, because it can be thick-walled and does not require a break line. Moreover, a removable seal reduces the risk that parts of the seal ride on the membrane or stick to the sensor shaft, which may reduce the quality of the measurement. In a preferred embodiment, the seal is both removable and penetrable. In this case, the sensor actually works with a high probability that the user forgets to remove the seal.

[0058]

[0058] Preferably the seal is made of a metal foil such as aluminium foil or a polymer foil such as HDPE which may be metallised for improved sealing properties.

[0059]

[0059] Preferably, the cartridge is provided in a closed container, such as a blister pack, which protects the cartridge from drying out and from becoming dirty. In such containers, any seal may be omitted, so that the user cannot forget to remove any seal. Preferably, however, the cartridge, in addition to being provided in a closed container, is provided with a seal, since the seal prevents contamination in the period immediately prior to installation and prevents the gel electrolyte from being inadvertently removed from the cylindrical support.

[0060]

[0060] In a preferred embodiment, at least one end of the cylindrical support is covered by a removable cartridge cap. Preferably, the upper end of the cylindrical support is covered by a removable upper cartridge cap and the lower end of the cylindrical support is covered by a removable lower cartridge cap. In particular, the upper and lower cartridge caps are connected by a connector. Preferably, at least one of the cartridge caps is equipped with a lug.

[0061]

[0061] Such a cartridge cap protects the gel electrolyte from drying out completely, thereby increasing the shelf life of the cartridge. Moreover, the removable cartridge cap can prevent the gel electrolyte from unintentionally slipping off the cylindrical support. The removable cartridge cap is efficient when protecting the gel electrolyte, because its thickness and stiffness of its sheet on the cylindrical support can be selected to reach the desired sealing properties. Moreover, the removable cartridge cap is easier to hold and remove from the cylindrical support than the removable seal. In a preferred embodiment, the penetrable seal is arranged below at least one of the cartridge caps. In this case, the protection and shelf life of the cartridge is further increased. Preferably, the cartridge cap comprises a cylindrical section having an inner diameter intended to receive the outer diameter of the cylindrical support. Preferably, the removable cartridge cap is made of a flexible material, the inner diameter of the cylindrical section being equal to or slightly smaller than the outer material of the cylindrical support, and the restoring force of the flexible material presses the cylindrical section of the cartridge cap against the cylindrical support, thereby forming a seal. The cylindrical section of the cartridge cap is closed at one end by a preferably flat end section, the lugs and connectors being preferably attached to or formed from the end section.

[0062]

[0062] Providing a lug on at least one of the cartridge caps facilitates removal of the cartridge cap from the cylindrical support. Preferably, the thickness of the lug is greater than the thickness of the connector.

[0063]

[0063] The embodiment in which the upper and lower cartridge caps are connected by a connector has the advantage that the risk of dropping the caps after removal from the cylindrical support is reduced. Furthermore, the manufacture of the cartridge caps is facilitated.

[0064]

[0064] Preferably, the removable cartridge cap is made of a flexible polymer. Most preferably, the removable cartridge cap is made of silicone. In particular, the material of the cartridge cap has greater flexibility than the material of the cylindrical support, so that the cartridge cap can be deformed during the removal process, while the cylindrical support retains its shape. This prevents the gel electrolyte from peeling off from the inside of the cylindrical support before it should.

[0065]

[0065] Preferably, the cartridge is provided in a closed container, such as a blister pack, which protects the cartridge from drying out and from becoming soiled. In such containers, any cap may be omitted, so that the user does not remove the cap. Preferably, however, the cartridge, in addition to being provided in a closed container, is provided with a cartridge cap, as this prevents soiling during the period immediately prior to installation and prevents the gel electrolyte from being inadvertently removed from the cylindrical support.

[0066] In one embodiment of the cartridge, the shape and wall thickness of the cylindrical support correspond to a step formed on the inside of the empty support cap, whereby the outside of the cylindrical support corresponds to the inner wall of the empty support cap above the step. Preferably, the inside of the cylindrical support corresponds to the inner wall of the empty support cap below the step, or the inner diameter of the cylindrical support is smaller than the inner wall of the empty support cap below the step.

[0067] In this context, the orientation is described by the membrane being "down" to the side of the opening for inserting the sensor shaft. This description is purely intended to describe the relative positions of the different parts with respect to each other, and is not intended to limit the orientation of the sensor, device, or empty support cap with respect to the local gravitational field during use or assembly.

[0068]

[0068] The use of the step and the corresponding shape of the empty support cap and cartridge as a means for positioning the cartridge in the sensor allows the cartridge to be mounted in a particularly easy way, since it only needs to be pressed inside the empty support cap. If the empty support cap is oriented so that the opening points downwards, the entire cartridge can be positioned in the reference frame defined by the local gravitational field by sticking the tip of the sensor shaft to the gel electrolyte. If required, and if there is a seal on both sides, the fingertip can be held against the opposing opening of the cylindrical support to keep the gel electrolyte inside, the seal preventing the gel electrolyte from sticking to the finger. If there is a seal at this opposing opening, the seal is removed when the cartridge is stuck to the tip of the sensor shaft. The sensor shaft is then inserted into the empty support cap with the cartridge at the tip of the sensor shaft. During this insertion, the cylindrical support can slide out of the gel electrolyte along the sensor shaft or into the empty support cap. When the cylindrical support slides into the empty support cap and in the nominal case where the cylindrical support stays around the electrolyte gel, the cylindrical support will be stopped in its movement by the step. At the very end when this happens, the insertion of the sensor shaft will dislodge the gel electrolyte from the cylindrical support and bring it to the membrane, where it will deform into its desired shape for the sensor. Usually, the sensor shaft is connected at the opposite side of its tip to a sensor head, which often comprises mounting structures such as screws, connectors, etc., to connect the sensor to at least a part of the readout electronics, the transmitter, and / or the display, and / or the readout electronics. The sensor head generally has a larger diameter than the sensor shaft, and therefore the sensor head prevents the cylindrical support from falling off the sensor shaft. Thus, in the assembled sensor, the cylindrical support is located in a volume bounded by the step on one side and by the sensor head on the other side. In other embodiments, the sensor shaft comprises a limit for the movement of the cylindrical support that is different from the sensor head.In some embodiments, the cylindrical support is used to position the sensor shaft relative to the empty support cap such that in the assembled sensor, the cylindrical support contacts both a step on the empty support cap and a limit on the sensor shaft and sensor head, respectively.

[0069]

[0069] Placing such a step as part of the empty support cap, on the one hand, ensures that the pre-disposed gel electrolyte has a clearly defined path for travel between the cartridge and the membrane. Furthermore, by using a different shape of the inner wall of the empty support cap above the step and a correspondingly different shape of the outside of the cylindrical support, a user may be prevented from combining an empty support cap with a reinforced membrane with an inappropriate gel electrolyte.

[0070]

[0070] The sensor according to the invention is preferably a Severinghaus or Clark type sensor. The sensor according to the invention comprises a reinforced membrane and a sensor shaft. The sensor shaft comprises an electrode. The reinforced membrane separates the process medium from the sensor shaft so that the species to be measured can pass through. The electrolyte fills the volume between the reinforced membrane and the sensor shaft. The sensor according to the invention is characterized in that the electrolyte is a gel electrolyte.

[0071]

[0071] The use of a gel electrolyte, an electrolyte that is unable to flow under conditions normally expected in such sensors during measurement and sterilization, allows the sensor to be mounted in all orientations without risk of losing electrolyte between the membrane and the sensor shaft.

[0072]

[0072] Clark type sensors are preferably used to measure dissolved oxygen. Clark type sensors generally consist of a platinum cathode and a silver anode, which are conductively connected by a gel electrolyte. Similarly, combinations of other metals as electrodes are possible. The electrodes are separated from the process medium by an oxygen-permeable membrane. In the case of a platinum / silver electrode combination, a polarization voltage of about -800 to -500 mV is applied to the platinum cathode with respect to the silver or platinum anode. Oxygen, according to its partial pressure, diffuses through the membrane into the measuring chamber filled with the gel electrolyte and is reduced at the cathode to hydroxide ions (OH-). At the silver anode, silver will be oxidized and, in the presence of chlorides, AgCl, which cannot dissolve, will adhere to the electrode. In the case of the platinum anode, OH - is oxidized to O2. The current is directly proportional to the partial pressure of oxygen, p(O2), which can be used to determine the oxygen concentration. The sensor shaft of the Clark-type sensor comprises a cathode and an anode. In some embodiments, the sensor shaft of the Clark-type sensor comprises additional electrodes, such as a reference electrode and / or a guard electrode. The support cap of the Clark-type sensor comprises an oxygen-permeable membrane.

[0073]

[0073] Preferably, the Clark-type sensor can be used to measure other oxidizable or reducible gases, such as ozone or hydrogen, applying the same measurement principle but using different membranes, gel electrolytes, and polarization potentials optimized for the gas being measured.

[0074]

[0074] The Severinghaus sensor may preferably be used to measure dissolved CO2. The Severinghaus principle utilizes the correlation between dissolved CO2 and the pH of a liquid. The potentiometric Severinghaus sensor utilizes a bicarbonate buffer system in contact with the process medium through a selective CO2 permeable membrane. The bicarbonate buffer system is provided in the form of a gel electrolyte. The pH value of this buffer system is related to the partial pressure of dissolved CO2 present in the process medium. CO2 from the medium diffuses across the membrane until it equilibrates in the buffer solution. Changes in CO2 partial pressure result in pH changes in the electrolyte that are detected by the inner body pH electrode, which is the sensor shaft. The inner body pH electrode is preferably a combination glass electrode consisting of a reference and a measurement system. The reference system uses an internal electrolyte, also called reference electrolyte, with a ceramic septum. The reference system further comprises a reference electrode inserted in the reference electrolyte. The measurement system uses a pH sensitive glass and an internal electrolyte, also called intrinsic electrolyte. The measurement system further comprises a measurement electrode inserted in the intrinsic electrolyte. The inner body pH electrode measures pH as the potential between a measurement electrode inserted in a measurement system and a reference electrode inserted in a reference system. The support cap of the Severinghaus sensor includes a selectively CO2 permeable membrane.

[0075]

[0075] Preferably, the Severinghaus sensor is used to measure other acid or alkaline gases, such as, for example, NH3, applying the same measurement principle using electrolytes and membranes optimized for the above compounds, such as ammonium-based pH buffers and membranes permeable to NH3, in the case of a Severinghaus sensor measuring NH3.

[0076]

[0076] A sensor for measuring species in a process medium may be assembled from a set. A set according to the present invention comprises a sensor shaft, a device, and a reinforced membrane. The sensor shaft comprises an electrode. The device comprises a pre-disposed gel electrolyte. The set further comprises the reinforced membrane. In some embodiments, the reinforced membrane is part of the device. In these embodiments, the device is preferably a support cap with gel electrolyte pre-disposed therein. In other embodiments, the set further comprises an empty support cap with the reinforced membrane. In these embodiments, the device is preferably a cartridge with gel electrolyte pre-disposed therein.

[0077]

[0077] The sensor according to the invention can be assembled with this set by placing the pre-disposed gel electrolyte from the device between the reinforcing membrane and the sensor shaft. This is preferably done by pressing and / or deforming the pre-disposed gel with the sensor shaft while inserting the sensor shaft into the support cap with the reinforcing membrane. The assembly is intuitive and comfortable and can be done in any orientation. In a preferred embodiment of the set, the device is a cartridge. The set further comprises an empty support cap. The cartridge comprises a cylindrical support having a certain shape and a certain wall thickness. In this embodiment, a step is formed on the inside of the empty support cap. The outside of the cylindrical support of the cartridge corresponds to the inner wall of the empty support cap above the step. In a preferred embodiment, the inside of the cylindrical support of the cartridge corresponds to or has a smaller diameter than the inner wall of the empty support cap below the step.

[0078]

[0078] In this context, the orientation is described by the membrane being "down" to the side of the opening for inserting the sensor shaft. This description is purely intended to describe the relative positions of the different parts with respect to each other, and is not intended to limit the orientation of the sensor, device, or empty support cap with respect to the local gravitational field during use or assembly.

[0079]

[0079] The word "empty" indicates that each portion does not have a pre-disposed gel electrolyte, but that each portion may have other portions such as protective portions and / or functional portions such as, for example, in the case of an empty single-use adapter, an empty support cap, and in the case of an empty support cap, a spacer mesh and / or a sealing structure.

[0080]

[0080] Providing a pre-disposed gel in the cartridge increases the shelf life of the part with the empty support cap and allows the user to adapt the sensor to their specific needs by selecting between different electrolytes. In certain preferred embodiments, the set with the empty support cap further comprises a single-use bag in which an empty single-use sensor adapter is mounted. The empty single-use sensor adapter is an embodiment of the empty support cap used in this case.

[0081]

[0082] Preferably, the single-use bag in which the empty single-use sensor adapter is loaded is sterilized.

[0082]

[0083] The set is particularly comfortable to use, since the user only needs to insert the sensor shaft and the cartridge. The reinforced membrane of the empty single-use sensor adapter forms a sterile barrier between the inside and outside of the bag. Thanks to the pre-disposed gel electrolyte in the cartridge, the bag can be manipulated and positioned without restrictions regarding the orientation of the single-use adapter. If the single-use bag is not yet sterilized, the user can sterilize it.

[0083]

[0084] Preferably, the single-use bag is sterilized by gamma irradiation and the gelling agent of the gel electrolyte is agarose.

[0084]

[0085] Most preferably, the gel electrolyte comprises a CO2 buffer and the single-use sensor adapter of the single-use bag comprises a selectively CO2 permeable membrane that forms a sterile barrier as well as part of the sensor. By inserting the sensor shaft of the Severinghaus sensor into the single-use sensor adapter, the partial pressure of CO2 of the process medium maintained inside the single-use bag can be determined in an easy and reliable manner.

[0085]

[0086] A preferred set according to the invention comprises a sensor shaft with electrodes suitable for determining the pH value of a medium surrounding the sensor shaft, and a device with a pre-disposed gel electrolyte, the gel electrolyte comprising a buffer for the species to be measured.

[0086]

[0087] This preferred set is suitable for constructing a Severinghaus sensor that measures the partial pressure of a dissolved gas, such as CO. Such measurements provide high resolution at low CO partial pressures, such as those common in bioprocessing applications.

[0087]

[0088] A method of producing a device according to the invention includes preparing an electrolyte with a gelling agent and dispensing said electrolyte into the support cap or cylindrical support for in situ jellification. Alternatively, a liquid electrolyte is dispensed into the support cap or cylindrical support followed by the addition of a gelling agent to jellify the electrolyte in situ.

[0088]

[0089] Jellifying the electrolyte in situ ensures that the shape of the resulting gel electrolyte corresponds to the inherent shape of the support cap and cylindrical support, respectively. This close correspondence in shape minimizes air bubbles trapped between the gel electrolyte and the support cap and cylindrical support, respectively, which increases shelf life. Furthermore, the resulting gel electrolyte will never fall off the support cap and cylindrical support, respectively, even though the materials are preferably not adhesively bonded to one another.

[0089]

[0090] The method of producing the device according to the invention preferably further comprises the step of applying a removable or penetrable seal onto the gel electrolyte. In some embodiments, the seal in the form of a foil is simply placed onto the almost completely gelled gel, whereby the seal adheres to the gel electrolyte by surface forces. In other embodiments, a soluble adhesive is used to adhere the seal in the form of a foil to the gel electrolyte. In yet other embodiments, the seal is formed by a coating, which may be a soluble coating. In some embodiments, the seal is applied to attach to a support cap or cylindrical support that surrounds the gel electrolyte. The seal may be made of a metal foil, such as an aluminum foil, or a polymer foil, such as HDPE, that may be metallized for improved sealing properties.

[0090]

[0091] The method for producing the device according to the invention preferably further comprises a step of closing the opening of the support cap or at least one end of the cylindrical support by a removable protective part. The removable protective part is preferably made of elastic plastic. The step of closing the support cap or the cylindrical support preferably comprises the task of pressing the removable protective part onto the part in question. The user can remove the removable protective part in this case simply by pulling it apart.

[0091]

[0092] Preferably, the seal and / or removable protector is applied after the gel electrolyte has gelled, so that the shape of the gel electrolyte is not inadvertently altered by these steps.

[0092]

[0093] A method of producing a device in the form of a cartridge preferably includes the step of placing the cylindrical support on a material suitable for forming a seal prior to dispensing the electrolyte with gelling agent into the cylindrical support.

[0093]

[0094] Preferably, the material suitable for forming the seal is an aluminium foil or a polymer foil such as HDPE or metallised HDPE.

[0094]

[0095] This embodiment has the advantage that a material suitable for forming a seal is used to close the mould formed by the cylindrical support during production of the cartridge as well as the seal for the finished cartridge, thus facilitating production.

[0095]

[0096] In another embodiment, a method of producing a device in the form of a cartridge preferably includes the step of placing the cylindrical support on a material suitable for forming a seal, prior to dispensing the liquid electrolyte, followed by the gelling agent, into the cylindrical support.

[0096]

[0097] A method of producing a device in the form of a cartridge preferably includes the step of placing a cartridge cap onto one end of the cylindrical support prior to dispensing the electrolyte with gelling agent into the cylindrical support, or prior to dispensing liquid electrolyte followed by gelling agent into the cylindrical support.

[0098] Preferably, the material of the cartridge cap is silicone.

[0097]

[0099] This embodiment has the advantage that the cartridge cap is used to close the mould formed by the cylindrical support during production of the cartridge as well as to seal the gel electrolyte of the finished cartridge from the surroundings, thus facilitating production.

[0098]

[0100] Preferably, prior to dispensing the electrolyte into the cylindrical support, the cartridge cap placed on one end of the cylindrical support is a lower cartridge cap placed on the lower end of the cylindrical support, and the method of producing the device is followed by the step of placing the upper cartridge cap on the upper end of the cylindrical support, whereby the upper cartridge cap is preferably attached to the lower cartridge cap using a flexible connection.

[0099]

[0101] In another method of producing a device in the form of a cartridge, a cylindrical support filled with a gel electrolyte is provided and cartridge caps are placed on both of its ends.

[0100]

[0102] The method for producing a device in the form of a support cap preferably comprises the step of applying a soluble coating onto the reinforced membrane. The soluble coating is preferably applied on the side of the membrane facing the process medium to be measured. The reinforced membrane is fluid-tight. The soluble coating can therefore be applied by any common method of applying liquid coatings, such as dipping or spraying. When the soluble coating is completely dry, it can be covered by a protective cap to avoid undesired contact with liquids or mechanical damage. In the case of a single-use sensor adapter mounted in a single-use bag, such a protective cap is not required since the bag itself has a protective function.

[0101]

[0103] The method of producing a sensor includes mounting a support cap onto the sensor shaft. In one embodiment, the support cap includes pre-disposed gel electrolyte. In another embodiment, the support cap is an empty support cap with a step on which the cartridge is placed. If a removable seal, removable cartridge cap, or removable protective part, protective cap on the support cap or cartridge, respectively, is present, they are removed prior to mounting the support cap onto the sensor shaft. Pressure of the sensor shaft during insertion into the support cap causes the gel electrolyte to be evenly distributed between the support cap and the sensor shaft.

[0102]

[0104] In a preferred embodiment of the method for producing the sensor, the cartridge is placed on the sensor shaft tip. The sensor shaft is inserted into a support cap with a step, with the cartridge on its tip. During insertion, the cylindrical support of the cartridge contacts the step and the gel electrolyte is forced out of the cylindrical support by the movement of the sensor shaft. The gel electrolyte is pressed by the sensor shaft against the reinforcing membrane, thereby deforming and distributing evenly between the support cap and the sensor shaft.

[0105] The following figures illustrate the invention. [Brief description of the drawings]

[0103] [Figure 1] FIG. 1 is a diagram of a sensor according to the present invention. [Figure 2a] FIG. [Figure 2b] FIG. 1 is a diagram of a single-use sensor adapter. [Figure 3a] FIG. 2 is a diagram of an empty support cap. [Figure 3b] FIG. 2 is a diagram of an empty single-use sensor adapter. [Figure 3c] FIG. 3b is a diagram of a cartridge for use with the empty support cap of FIG. 3a. [Figure 4] FIG. 1 is a diagram of a single-use bag with a single-use sensor adapter. [Figure 5a] FIG. 2b is a diagram of the support cap of FIG. 2a having a removable protective portion and a soluble coating. [Figure 5b] FIG. 1 illustrates a cartridge having a removable and penetrable seal. [Figure 5c] FIG. 2 is a diagram of a cartridge having upper and lower cartridge caps. [Figure 5d] FIG. 5c is a cross-sectional view of the cartridge. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0104]

[0106] FIG. 1 shows a sensor 2 according to the invention. The sensor 2 comprises a sensor head 22, which receives an electrode 212 and connects the electrode 212 to an interface 23 for data transmission, e.g. a plug for a data cable. The sensor 2 further comprises a sensor shaft 21. Two electrodes 212 extend from the sensor head 22 into or along the sensor shaft 21. In the example shown in FIG. 1, the electrode 212 extends into the sensor shaft 21 and is surrounded by an internal electrolyte. In the embodiment shown, the sensor shaft 21 comprises two coaxially arranged chambers. The electrodes 212 are arranged in all of the chambers. The internal chamber extends further outward from the sensor head 22 and ends at a sensor shaft tip 211 formed at least in part by pH glass. The internal chamber with its electrode 212, its internal electrolyte, also called intrinsic electrolyte, and its pH glass, is also called the measurement system. The external chamber comprises a septum 213. The external chamber, with its electrode 212, its internal electrolyte, also called reference electrolyte, and its diaphragm 213, is also called the reference system. The sensor shaft tip 211 and part of the sensor shaft 21 are placed inside the device 1 in the form of a support cap 11. The support cap 11 has a cylindrical shape with a reinforced membrane 3 at one end and at the other end forming an opening 114. The device 1 is filled with a gel electrolyte 4, whereby the gel electrolyte 4 connects the membrane 3, the pH glass on the sensor shaft tip 211, and the diaphragm 213. The sensor 2 shown works according to the Severinghaus principle: whereby the gel electrolyte 4 comprises a buffer suitable for the species to be measured. The species to be measured diffuses through the reinforced membrane 3 and reacts with the buffer such that the pH value of the gel electrolyte 4 changes. The potential of the measurement system depends on the pH value of the gel electrolyte 4 with which the measurement system is in contact, measured against the reference system. An electrical connection between the gel electrolyte 4 and the electrode 212 of the reference system is established through the diaphragm 213 and the reference electrolyte. The gel state of the gel electrolyte 4 allows the sensor 2 according to the present invention to be assembled in any orientation.This is because the gel electrolyte 4 cannot flow out and thereby interrupt the connection between the membrane 3 , the sensor shaft tip 211 and the septum 213 .

[0105]

[0107] In other types of sensors 2 with electrodes 212, such as Clark-type sensors, the section of the sensor shaft 21 that needs to be covered by the gel electrolyte 4 can be different. For example, the electrodes 212 can be directly exposed to the gel electrolyte 4. In any case, the gel state makes it possible to ensure the necessary connection.

[0106]

[0108] FIG. 2a shows a support cap 11 in the form of a membrane body 11a. Such a membrane body 11a is intended to be used on a multi-purpose sensor 2. Most of its external surface is protected during use by a cap sleeve, leaving only the reinforced membrane 3 exposed to the process medium to be analyzed. The membrane body 11a consists of a cylindrical part, which is provided with an opening 114 on one side and with the reinforced membrane 3 on the other side. The membrane body 11a is partially filled with a gel electrolyte 4. The filling level of the gel electrolyte 4 is such that, when the sensor shaft 21 is inserted, the gel electrolyte 4 essentially fills the entire remaining volume of the membrane body 11a below the support cap seal structure 116. The cylindrical part is provided with a set of windows 115 covered with an elastic material. As part of the multi-purpose sensor 2, the membrane body 11a can be subjected to a steam sterilization process, during which the gel electrolyte 4 is exposed to a temperature of 120° C. or 140° C., whereby the gel electrolyte 4 expands. This causes the window 115 to bulge outward. During cooling, the elasticity of the window material pushes the gel electrolyte 4 back onto the sensor shaft 21, keeping the sensor 2 functional. The step 111 surrounding the opening 114 in the membrane body 11a can be used as a limit stop to prevent the corresponding sensor shaft 21 from being inserted too far. Furthermore, the step 111 as well as the optional support cap seal structure 116 reduce the surface of the gel electrolyte 4 exposed to the surroundings in the assembled sensor 2, which prevents the gel electrolyte 4 from drying out, thereby increasing the sensor 2 life.

[0107]

[0109] FIG. 3a shows an empty support cap 11e in the form of an empty membrane body 11ae. Its shape and parts are similar to those shown in FIG. 2a, however, the empty support cap 11e is not pre-disposed with gel electrolyte 4. Furthermore, the step 111 is arranged such that the inner wall of the empty support cap 11e continues above the step 111. The step 111 serves as a limit stop for the corresponding cartridge 12 as shown in FIG. 3c. The step 111 formed on the inner side of the empty support cap 11e is such that the outer side of the cylindrical support 121 of the cartridge 12 corresponds to the inner wall of the empty support cap above the step 112, while the inner side of the cylindrical support 121 of the cartridge 12 corresponds to the inner wall of the empty support cap below the step 113. Thus, the limit stop acts only on the cylindrical support 121, but not on the pre-disposed gel 4 that may be pressed against the reinforced membrane 3. In such an embodiment, the exposed end of the cylindrical support 121 of the cartridge 12 can act as a limit stop for the sensor shaft 21 to be inserted into the empty membrane body 11ae and cartridge 12 combination. Another or additional way to ensure a minimum distance between the sensor shaft tip 211 and the reinforced membrane 3 is a spacer mesh 31 placed on top of the reinforced membrane 3. The spacer mesh 31 is made of a material that does not damage the sensor shaft tip 211 and does not damage the reinforced membrane 3. For example, the spacer mesh 31 can be made of nylon. Being a mesh, the spacer mesh 31 allows the gel electrolyte 4 to establish the desired contact. In the embodiment shown in FIG. 3a, the inner shape of the empty membrane body 11ae is further modified with respect to the shape shown in FIG. 2a in order to limit the inherent volume. This allows the amount of gel electrolyte 4 required to be reduced.

[0108]

[0110] FIG. 3c shows a cartridge 12 to be used with the empty support cap 11e shown in FIG. 3a. The cartridge 12 comprises a cylindrical support 121 filled with gel electrolyte 4. The inner circumference of the cylindrical support 121 and the shape of the cartridge 12 are such that the sensor shaft 21 passes completely through the cylindrical support 121 along its longitudinal axis up to an optional limit stop. This allows the gel electrolyte 4 to be pushed out of the cylindrical support 121 by the sensor shaft 21. The internal and external shapes of the cylindrical support 121 are such that their shapes correspond to the empty support cap 11e with which it is to interact.

[0109]

[0111] Figures 2b and 3b show a support cap 11 in the form of a single-use sensor adapter 7 and an empty support cap 11e in the form of an empty single-use sensor adapter 7e having an inserted cartridge 12. In the illustrated embodiment, the single-use sensor adapter 7 and the empty single-use sensor adapter 7e exhibit a number of common features, which will be described with respect to the empty single-use sensor adapter 7e shown in Figure 3b, but which apply equally to the single-use sensor adapter 7 of Figure 2b.

[0110]

[0112] The empty single-use sensor adapter 7e comprises two concentrically arranged cylindrical sections 71i, 71o. The inner cylindrical section 71i is closed by a reinforced membrane 3. The diameter of the inner cylindrical section 71i is such that the sensor shaft 21 can be inserted into it.

[0111]

[0113] The outer cylindrical section 71o surrounds the inner cylindrical section 71i. The two cylindrical sections 71i and 71o are connected in a fluid-tight manner at their lower ends. The upper end of the outer cylindrical section 71o is higher than the upper end of the inner cylindrical section 71i, and their connection is such that a hollow cylindrical volume 72 is formed between them. This volume 72 can hold excess gel electrolyte if required, but it is preferred that the pre-disposed amount of gel electrolyte and the height of the inner cylindrical section 71i are such that leakage is unlikely, even at high temperatures that may occur during the sterilization process.

[0112]

[0114] The external shape of the outer cylindrical section 71o is such that the outer cylindrical section 71o can be inserted into and connected to a standard 1'' Eldon James port. The internal shape of the outer cylindrical section 71o comprises a peripheral shoulder 711o in its lower part, on which the connecting portion 73 can be placed. The connecting portion 73 preferably comprises a peripheral outer rim 731 at its upper end corresponding to the shoulder 711o of the outer cylindrical section. The connecting portion 73 further comprises a shoulder 732 on its inner surface, preferably near its lower end. In this embodiment, the inner cylindrical section 71i comprises a recess 711i on its lower outer surface corresponding to the shoulder 732 of the connecting portion 73. The connecting portion 73 is equipped with a sealing means, such as an O-ring. In the assembled state, as shown, the outer rim 731 of the connecting portion 73 is disposed on the shoulder 711o of the outer cylindrical section 71o and the recess 711i of the inner cylindrical section 71i is disposed on the shoulder 732 of the connecting portion 73. It is the connecting portion 73 that connects the inner and outer cylindrical sections 71i, 71o in a fluid-tight manner.

[0113]

[0115] In the case of the single-use sensor adapter 7 shown in FIG. 2b, the gel electrolyte 4 is pre-disposed on the reinforced membrane 3 inside the inner cylindrical section 71i. The amount of pre-disposed gel electrolyte 4 is such that when the sensor shaft 21 is fully inserted and the sensor is formed, the gel electrolyte 4 fills the inner cylindrical section 71i essentially completely at room temperature, preferably to more than 90% of the desired fill level. In the case shown in FIG. 2b, the desired fill level is defined by a limit stop for the sensor shaft 712i formed as a circumferential step on the inside of the inner cylindrical section 71i close to the opening 114.

[0114]

[0116] In the case of the empty single-use sensor adapter 7e shown in FIG. 3b, the gel electrolyte 4 is pre-disposed inside the cylindrical support 121 of the cartridge 12. To receive the cartridge 12, the inner cylindrical section 71i is provided with a step 111 near its opening 114. In the embodiment shown in FIG. 3b, the outside of the cylindrical support 121 corresponds above the step 111 to the inner wall of the inner cylindrical section 71i, which is part of the empty support cap 11e. However, the inside of the cylindrical support 121 below the step 111 has a smaller diameter than the inner wall of the inner cylindrical section 71i. The amount of pre-disposed gel electrolyte 4 is such that when the sensor shaft 21 is fully inserted and the sensor is formed, the gel electrolyte 4 fills the inner cylindrical section 71i at room temperature essentially completely, preferably to more than 90% of the desired filling level. In the case shown in FIG. 2b, the desired fill level is defined by a limit stop for the sensor shaft 712i formed as a circumferential step on the inside of the inner cylindrical section 71i, close to the opening 114.

[0115]

[0117] 4 shows a single-use bag 5. The single-use bag 5 includes a port 51 to which a single-use sensor adapter 7 is attached. The single-use bag 5 is filled with a process medium 6 whose species is to be measured. The reinforced membrane 3 is in contact with the process medium 6 on one side and with a pre-disposed gel electrolyte 4 on the other side. The gel state of the gel electrolyte 4 keeps the gel electrolyte 4 on the reinforced membrane 3 even when the single-use sensor adapter 7 is mounted horizontally.

[0116]

[0118] 5a and 5b show how a pre-disposed gel electrolyte 4 can be protected from drying out and becoming soiled during shipping and storage.

[0117]

[0119] FIG. 5a shows the single-use sensor adapter 7, which has been described in detail with respect to FIG. 2b. The single-use sensor adapter 7 comprises a gel electrolyte 4 pre-disposed on the reinforced membrane 3 inside the internal cylindrical section. In this embodiment, a dissolvable coating 118 made of polyvinylpyrrolidone is applied to the outside of the reinforced membrane 3. Furthermore, a removable protective part 117 is pressed into the opening 114 of the internal cylindrical section. The removable protective part 117 is made of elastic plastic. The removable protective part 117 has a cylindrical section that transforms into a handle on one side and opens on the other side. The cylindrical part is equipped with a profile of a surrounding lip. The dimensions of the cylindrical part of the removable protective part 117 are such that the cylindrical part can be inserted into the internal cylindrical section such that the lip forms an airtight barrier against the environment. Thereby, the volume in which this gel electrolyte 4 is located is closed by the dissolvable coating 118, the removable protective part 117 and the internal cylindrical section of the single-use sensor adapter 7. This minimizes the drying rate of the gel electrolyte 4.

[0118]

[0120] To prevent dirt and mechanical damage as well as accidental removal of the soluble coating 118 or the removable protective portion 117 , the single-use sensor adapter 7 may be equipped with a further protective cap 74 .

[0119]

[0121] FIG. 5b shows how the pre-disposed gel electrolyte 4 of the cartridge 12 can be protected: there is a removable seal 122a made of aluminum foil attached to one side of the cartridge 12 in the embodiment shown. On the other side there is a penetrable seal 122b. In the embodiment shown, the penetrable seal 122b is also made of aluminum foil. However, the foil is significantly thinner than its nominal value along most of the cylindrical support 121. Such a thin section can be seen on the right side of FIG. 5b. In one section, the foil has its nominal thickness. This can be seen on the left of FIG. 5b. The foil forming the penetrable seal extends with its nominal thickness above the cylindrical support 121. If the user wants to remove this seal 122b as well, he can do so by gripping this extension. However, if the user does not want to remove it or forgets to do so and presses against it with the sensor shaft tip 211, the seal 122b will break, especially in thin locations, while its attachment to the cylindrical support 121 ensures that the remaining part of the seal 122b remains close to the cylindrical support 121 and does not interfere with the measurement.

[0120]

[0122] Figures 5c and 5d show another way in which the pre-disposed gel electrolyte 4 of the cartridge 12 can be protected: an upper cartridge cap 123b is placed at the upper end of the cylindrical support 121 and a lower cartridge cap 123a is placed at the lower end of the cylindrical support 121. Figure 5d shows a cross-section of the isometric view that can be seen in Figure 5c.

[0121]

[0123] Both cartridge caps 123a, 123b are formed similarly. Each cartridge cap 123a, 123b comprises a cylindrical section 123e having an inner diameter intended to receive the outer diameter of the cylindrical support 121. The cartridge caps 123a, 123b are made of silicone, which in this example is more flexible than the PEEK from which the cylindrical support 121 is made. The inner diameter of the cylindrical section is equal to or slightly smaller than the outer diameter of the cylindrical support 121, so that the restoring force of the flexible material presses the cylindrical section 123e of the cartridge cap 123a, 123b against the cylindrical support 121, thereby forming a seal. The cylindrical section 123e of the cartridge cap is closed at one end by a flat end section 123f. The lug 123d and the connector 123c are attached to this end section 123f. The connector 123c connects the upper and lower cartridge caps 123a, 123b. The connector 123c has the shape of a flat silicone band in the embodiment shown. The thickness of the material of the lug 123d is about twice the thickness of the end section 123f and the connector 123c. This makes the lug 123d less flexible than the end section 123f and the connector 123c and therefore more suitable for efficiently transmitting forces to the end section 123f. By pulling the lug 123d, the cartridge caps 123a, 123b can be easily removed from the cylindrical support 121.

[0122]

[0124] One method to produce gel electrolyte 4 is as follows: An aqueous electrolyte solution is heated above the melting temperature of agarose. 1-4 wt% of agarose is added and the mixture is stirred until clear. The desired amount of electrolyte is dispensed into an empty single-use sensor adapter, an empty membrane body, another empty support cap, or a cylindrical support. Gel formation occurs upon cooling to room temperature of 20 °C.

[0123]

[0125] One method to produce a gel electrolyte 4 for a Severinghaus sensor measuring CO2 is as follows: An aqueous electrolyte solution is heated above the melting temperature of agarose. 1-4 wt% of agarose is added and the mixture is stirred until clear. The mixture is cooled to 60-70 °C. Bicarbonate is added at this temperature. The desired amount of electrolyte is dispensed into an empty single-use sensor adapter, an empty membrane body, another empty support cap, or a cylindrical support. Gel formation occurs upon cooling to room temperature of 20 °C. [Explanation of symbols]

[0124] 1 Device 2 Sensors 3 Reinforced membrane 31 Spacer mesh 21 Sensor shaft 211 Sensor shaft tip 212 Electrode 22 Sensor head 23 Data transmission interface 4. Gel electrolyte 11 Support cap 11e Empty Support Cap 111 Step 112 Inner wall of empty support cap above step 113 Inner wall of empty support cap below step 114 Aperture 115 Windows 116 Support cap seal structure 11a Membrane body 11ae Empty membrane body 7 Single-use sensor adapters 7e Empty Single-Use Sensor Adapter 71i Inner Cylinder Section 711i recess Limit stop for 712i sensor shaft 71o Outer Cylinder Section 711o Shoulder 72 Volume 73 Connection part 731 External Rim 732 Shoulder 74 Protective Cap 5 Single-use bags 51 Port 118 Availability Coating 117 Removable protective part (opening side) 12 Cartridge 121 Cylindrical Support 122a, b Seal (removable, penetrable) 123a, b Cartridge caps (lower and upper) 123c flexible connection 123d Rug 123e Cylinder Section 123f End Section 6 Process media

Claims

1. A device (1) for a sensor (2) comprising a reinforced film (3) and an electrode (212) and an electrolyte between the sensor shaft (21) and the sensor (2), preferably the sensor (2) being suitable for measuring a species in a process medium (6), and the device (1) comprising a pre-displaced gel electrolyte (4).

2. The device (1) according to claim 1, wherein the gel electrolyte (4) is a non-fluid colloid or polymer network expanded throughout the entire volume of the gel electrolyte (4) by a fluid having desired electrolyte properties, and the gel electrolyte (4) preferably exhibits shearing and / or thixotropic behavior.

3. The device (1) according to claim 1, which is stable to sterilization procedures, preferably steam sterilization, autoclave, gamma ray, X-ray, or electron beam sterilization, by selecting a gelling agent that is stable to sterilization procedures, preferably by using a polysaccharide, most preferably agarose, as the gelling agent to create the gel electrolyte (4), or by using an adsorption-based or polymer-based gelling agent.

4. The device (1) according to claim 1, wherein the gel electrolyte (4) includes a buffer for the species to be measured.

5. The system comprises a support cap (11) having an opening (114), the support cap (11) holding a reinforcing film that forms a barrier between the process medium (6) and the sensor shaft (21), allowing insertion of the sensor shaft (21) in preparation for use and allowing the type to pass through during use of the sensor (2), the gel electrolyte (4) being pre-disposed within the support cap (11) on the side of the reinforcing film (3) facing the opening (114), and the support cap (11) preferably, a. A membrane body (11a) that can be attached to the sensor shaft (21), or b. A single-use sensor adapter (7) suitable for mounting in a single-use bag (5) and attachable to a sensor shaft (21). The device (1) according to any one of claims 1 to 4.

6. The device (1) according to claim 5, wherein the reinforcing film is in contact with the gel electrolyte (4) on one side and coated with a soluble coating (118), preferably a polymer, on the other side, and the soluble coating (118) dissolves when it comes into contact with a fluid, preferably the process medium (6).

7. The device (1) according to any one of claims 1 to 4, comprising a cartridge (12) and a cylindrical support (121) at least partially filled with the gel electrolyte, wherein the inner circumference of the device (1) and the cylindrical support is such that at least a portion of the sensor shaft (21) completely passes through the cylindrical support (121) along the longitudinal axis of the cylindrical support (121).

8. The device (1) according to claim 7, wherein the shape and wall thickness of the cylindrical support (121) correspond to a step (112) formed on the inside of the empty support cap (11e), so that the outside of the cylindrical support (121) corresponds to the inner wall of the empty support cap (11e) above the step (112), and preferably the inside of the cylindrical support (121) corresponds to the inner wall of the empty support cap (11e) below the step (113).

9. Sensor (2), preferably a Sevelinghaus or Clarke type sensor (2), comprising a reinforced membrane (3) and a sensor shaft (21), wherein the sensor shaft (21) comprises an electrode (212), the membrane separates a process medium (6) from the sensor shaft (21) so that a species to be measured can pass through, and an electrolyte fills the volume between the membrane and the sensor shaft (21), wherein the electrolyte is a gel electrolyte (4).

10. A single-use bag (5) comprising the single-use sensor adapter (7) described in claim 5, preferably a sterilized single-use bag (5).

11. A set for a sensor (2) that measures the species in a process medium (6), a. A sensor shaft (21) equipped with an electrode (212), b. A device (1) according to any one of claims 1 to 4, c. comprising a reinforcing film (3), wherein the reinforcing film (3) i. A part of the device (1), ii. Part of the empty support cap (11e), which is part of the set. It is a set.

12. a. The device (1) is the cartridge (12) described in claim 8, b. The set further comprises an empty support cap (11e), i. The set according to claim 11, wherein the outer surface of the cylindrical support (121) of the cartridge (12) corresponds to the inner wall of the empty support cap (11e) above the step (112).

13. a. The set according to claim 12, further comprising a single-use bag (5) on which the empty support cap (11e) in the form of an empty single-use sensor adapter (7e) is mounted.

14. a. The sensor shaft (21) is equipped with an electrode (212) suitable for determining the pH value of the medium surrounding the sensor shaft (21), b. The set according to claim 11, wherein the device (1) comprises a pre-displaced gel electrolyte having a buffer for the species to be measured.

15. A method for producing a device (1) according to any one of claims 1 to 4, comprising the steps of: preparing an electrolyte using a gelling agent; dispensing the electrolyte into an empty support cap (11e) or cylindrical support (121) for in-situ gelling; or dispensing a liquid electrolyte into the empty support cap (11e) or cylindrical support (121), followed by adding a gelling agent for in-situ gelling.

16. A method for producing the sensor described in claim 9, comprising the step of mounting a support cap on the sensor shaft, The support cap is equipped with a pre-displaced gel electrolyte, or The support cap has a step on which the cartridge is placed, and the cartridge is placed after the removable seal is removed from the cartridge as needed. The pressure of the sensor shaft during insertion into the support cap causes the gel electrolyte to be evenly distributed between the support cap and the sensor shaft. method.

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