Combination sensor and system for determining the ph value and the oxygen content of a liquid

Abstract

The invention relates to a combination sensor (2) for determining the pH value and oxygen content of a liquid (5) to be analysed, in particular in a bioreactor (3), comprising a measuring module (4), a signal processing module (6) and a coupling device (8) for coupling the measuring module (4) and the signal processing module (6) to one other. The measuring module (4) contains at least one optical waveguide (40) and a single-rod measuring chain having a reference half-cell (60) and a measuring half-cell (50), wherein the at least one optical waveguide (40) and the measuring half-cell (50) are arranged within the reference half-cell (60). The signal processing module (6) contains electronic components (41, 42, 44) which are designed to convert light signals transmitted through the optical waveguide (40) into electrical signals in order to make it possible to determine, from the light signals to be transmitted through the optical waveguide (40), the oxygen content of the liquid (5) to be analysed and to process electrical signals which are provided at a measuring electrode (54). The coupling device (8) has a first coupling part (81), which is provided on the measuring module (4), and a complementary second coupling part (82), which is provided on the signal processing module (6), wherein the first coupling part (81) and the second coupling part (82) can be releasably coupled to each other. The coupling device (8) is designed to transmit light signals transmitted through the optical waveguide (40) and electrical signals provided at the measuring electrode (54) from the measuring module (4) to the signal processing module (6) when the first coupling part (81) and the second coupling part (82) are coupled to one other.

Description

[0001] Combined sensor and system for determining the pH and oxygen content of a liquid

[0002] The invention relates to a combination sensor and a system for determining the pH value and oxygen content of a liquid. The invention particularly relates to a modular combination sensor comprising a measuring module and a signal processing module.

[0003] Combined sensors are used to determine the pH and oxygen content of a liquid to be analyzed, for example in a bioreactor.

[0004] To determine the pH value, a so-called combination electrode is often used. A combination electrode is a combination of a working electrode and a reference electrode in a common housing for measuring the pH value. The term "working electrode" is also used synonymously with the term "measuring electrode" or "measuring half-cell," and the term "reference electrode" is also used synonymously with the term "reference half-cell."

[0005] A bioreactor, often also called a fermenter, is a container in which specific microorganisms, cells, or small plants are cultivated (also: fermented) under optimal conditions. The operation of a bioreactor is thus an application of biotechnology that utilizes or makes usable biological processes (bioconversion, biocatalysis) in technical facilities. Small bioreactors, in particular, have a limited number of sensor connections, which limits process control.

[0006] Combined sensors contain wearing parts that have a relatively short lifespan and must be replaced frequently, as well as electronic components that have a significantly longer lifespan than the wearing parts.

[0007] It is an object of the invention to provide an efficient and improved combination sensor with the lowest possible acquisition and operating costs. A combination sensor according to the invention for determining the pH value and the oxygen content of a liquid to be analyzed, for example in a reactor, in particular in a bioreactor, comprises a measuring module, a signal processing module, and a coupling device. The coupling device is intended and designed to detachably couple the measuring module and the signal processing module to one another.

[0008] The measuring module comprises at least one optical fiber and at least one combination measuring chain. The combination measuring chain has at least one measuring half-cell and at least one reference half-cell. The reference half-cell comprises a reference chamber filled with a reference electrolyte, a reference electrode, and a diaphragm, also referred to as a reference diaphragm. The measuring half-cell is arranged within the reference half-cell and comprises a measuring chamber filled with a measuring electrolyte, a measuring electrode, and a measuring membrane formed on the front side of the measuring module. The measuring electrolyte in the measuring chamber is an electrolyte solution that acts as an internal buffer.

[0009] The measuring membrane is designed to establish electrical contact between the measuring electrolyte and the liquid to be analyzed when the measuring module is at least partially immersed in the liquid to be analyzed. The measuring membrane is particularly constructed such that an electrochemical potential at the measuring electrode changes depending on the concentration of hydrogen ions in the liquid to be analyzed when the measuring membrane is in contact with the liquid to be analyzed. The measuring membrane can, for example, be part of a glass electrode. The glass electrode can, in particular, be made of PHI glass.

[0010] The signal processing module contains electronic components. The electronic components comprise, in particular, at least one electrical light source, for example, an LED, which is designed to generate light that is radiated into the optical waveguide. The electronic components comprise, in particular, at least one light detector, which comprises, for example, a photodiode and is designed to detect light signals transmitted through the optical waveguide to the signal processing module and to convert them into electrical signals. The electronic components in the signal processing module also comprise components designed to process electrical signals provided by the at least one light detector in order to determine the oxygen content in the liquid to be analyzed from the electrical signals provided by the at least one light detector.

[0011] The electronic components in the signal processing module also include electronic components designed to process electrical signals provided by the combination measuring chain in order to determine the pH value of the liquid to be analyzed from the provided electrical signals.

[0012] The electronic components may include resistors, capacitors, diodes, transistors, and / or integrated electronic semiconductor circuits. The electronic components may also include at least one programmable microprocessor.

[0013] The measuring module has a measuring module housing in which the optical fiber and the combination measuring chain are arranged. The measuring half-cell of the combination measuring chain can, in particular, be formed by the measuring module housing. The signal processing module has a signal processing module housing in which the electronic components are arranged.

[0014] The housings can be made of plastic or stainless steel, for example. The measurement module housing and the signal processing module housing can be made of the same material or different materials.

[0015] The coupling device comprises a first coupling part provided on the measuring module and a complementary second coupling part provided on the signal processing module. The first coupling part and the second coupling part can be releasably coupled to one another.

[0016] The coupling device is designed to transmit light signals transmitted through the optical fiber and electrical signals, in particular signals provided by the combination measuring chain, between the signal processing module and the measuring module when the first coupling part and the second coupling part are coupled to one another. The coupling device is designed, in particular, to transmit light signals generated by the light source in the signal processing module into the optical fiber in the measuring module, as well as to transmit light signals from the optical fiber in the measuring module to the signal processing module so that they can be detected by the light detector in the signal processing module.

[0017] The coupling device of a combination sensor according to the invention makes it possible to separate the wear-prone measuring module, which generally has a significantly shorter service life than the signal processing module, from the signal processing module and replace it when it has reached the end of its service life. In this way, the typically significantly more durable signal processing module can be coupled and operated sequentially with a plurality of measuring modules. Consequently, the expensive and long-lasting electronic components in the signal processing module do not have to be replaced each time a measuring module reaches the end of its service life. The operating costs of a combination sensor according to the invention can thus be significantly reduced through the repeated replacement of the measuring module and the continued use of the signal processing module.

[0018] In one embodiment, the first coupling part and the second coupling part are coupled to one another in such a way that they can be connected to and detached from one another without tools. The measuring module and the signal processing module can be coupled to one another, in particular, by a plug connection, a screw connection, a bayonet connection, and / or a snap-in connection. In this way, it is possible to quickly, easily, and conveniently separate the signal processing module from the measuring module and connect it to a new measuring module in order to replace it as needed.

[0019] In one embodiment, the measuring module and the signal processing module are designed such that the combined sensor is fluid-tight when coupled. This allows the combined sensor to operate safely and reliably even in humid and wet environments.

[0020] In one embodiment, the first coupling part and the second coupling part each have a plurality of electrical contacts for transmitting the electrical signals between the measuring module and the signal processing module. The electrical contacts can, in particular, be designed to establish one or more electrical connections between the measuring electrode and at least one electronic component in the signal processing module.

[0021] In one embodiment, the first coupling part and the second coupling part each have an optical interface for transmitting the light signals between the measuring module and the signal processing module.

[0022] In one embodiment, the electrical contacts are arranged around the optical interface. This allows the first coupling part and the second coupling part to be designed particularly compactly.

[0023] In one embodiment, the optical waveguide has a light-conducting core. The light-conducting core can be encased to stabilize the optical waveguide and protect it from harmful external influences, such as mechanical and / or chemical influences that may originate from the liquid to be analyzed. The cladding can prevent or at least reduce loss or attenuation of the light signals in the optical waveguide. The core of the optical waveguide can be, for example, a glass core or a fiber optic core. The optical waveguide can be encased in a material, such as stainless steel or a suitable plastic, that is inert to the electrolyte in the reference half-cell.

[0024] In one embodiment, the signal processing module comprises a signal processing module optical fiber extending within the signal processing module into the second coupling part. The signal processing module optical fiber can be split into a first optical fiber strand and a second optical fiber strand immediately outside the second coupling part. The first optical fiber strand can extend from the second coupling part to the light source to receive light from the light source and transmit it via the coupling device into the optical fiber in the measuring module. The second optical fiber strand can extend from the second coupling part to the light detector to supply the light detector with light from the optical fiber located in the measuring module.

[0025] In one embodiment, the measuring module extends in a longitudinal direction. The optical fiber and the combination measuring chain with the measuring half-cell and the reference half-cell can also extend in the longitudinal direction through the measuring module. A combination sensor that extends essentially in a longitudinal direction can be introduced particularly easily and efficiently into a reactor or bioreactor such that a distal region of the measuring module comes into contact with the liquid to be analyzed in the reactor.

[0026] The first coupling part and the second coupling part can be connected to and separated from one another by a mutual movement that includes a component aligned in the longitudinal direction. By means of a movement that includes a component aligned in the longitudinal direction, the measuring module with the first coupling part and the signal processing module with the second coupling part can be coupled to and separated from one another particularly easily and efficiently.

[0027] The combination of at least two sensors, which allow the determination of both the pH value and the dissolved oxygen content in a liquid to be analyzed and which are arranged in a common sensor housing, eliminates at least one sensor connection to the reactor and enables the measurement of additional parameters, even in small reactors. The measurement of additional parameters enables a direct improvement of the processes taking place in the reactor.

[0028] In one embodiment, the optical fiber is arranged within the combination measuring chain, in particular in the measuring half-cell or the reference half-cell. The optical fiber can extend, in particular, longitudinally through the measuring half-cell or the reference half-cell. Arranging the optical fiber within the combination measuring chain enables a particularly compact design of the measuring module.

[0029] In one embodiment, the optical waveguide is arranged in particular within the reference half-cell. In this way, the optical waveguide and the electrolyte in the reference half-cell share the volume provided by the reference half-cell. As a result, the volume available for the electrolyte in the reference half-cell can be increased. By increasing the electrolyte volume in the reference half-cell, the service life of the reference half-cell can be increased. In one embodiment, the optical waveguide is designed such that a distal end region of the optical waveguide, which is located at a distal end of the measuring module facing away from the signal processing module, is in the liquid to be analyzed when the measuring module is arranged in the liquid to be analyzed.

[0030] In one embodiment, the optical waveguide is provided with a fluorescent dye that interacts with light irradiated into the optical waveguide. The optical waveguide can, in particular, have a light input surface formed on or in an end face at the distal end of the measuring module and coated with the fluorescent dye, so that the fluorescent dye is in contact with the liquid to be analyzed when the measuring module is arranged in the liquid to be analyzed.

[0031] The fluorescent dye may be configured or selected to be excited by the light generated by the light source in the signal processing module and transmitted through the optical fiber to the light input surface of the optical fiber.

[0032] The fluorescent dye can, in particular, be designed such that the wavelength or frequency of the light emitted by the fluorescent dye upon optical excitation depends on the oxygen content of the liquid to be analyzed at the light input surface. In this way, the oxygen content of the liquid to be analyzed can be determined by evaluating the light emitted by the fluorescent dye, which is at least partially radiated into the optical waveguide.

[0033] In one embodiment, the light source is designed to generate blue light. The light source can, in particular, be designed to generate light with a wavelength in the range of 400 nm to 500 nm, in particular light with a wavelength of 450 nm.

[0034] Light in a wavelength range of 400 nm to 500 nm has proven particularly suitable for exciting fluorescent dyes suitable for determining the oxygen content of the liquid to be analyzed. In one embodiment, the light detector is designed to determine the wavelength of the light supplied to the light detector through the optical fiber in order to determine the oxygen content of the liquid to be analyzed. The light detector can, in particular, be designed to determine a wavelength shift and / or a phase shift of the light supplied to the light detector through the optical fiber compared to the light radiated into the optical fiber by the light source.

[0035] A light filter can be arranged in front of the light detector, i.e., in the light path between the optical fiber and the light detector, to filter the light emitted from the optical fiber onto the light detector. The light filter can, in particular, be designed such that it is essentially transparent to light with wavelengths in a range of 750 nm to 880 nm and blocks or at least significantly attenuates light outside this wavelength range.

[0036] With the help of such a light filter, the light detected by the light detector can be reduced to light with the wavelengths relevant for determining the oxygen content of the liquid being analyzed. The reliability and accuracy of the determination of the oxygen content of the liquid being analyzed can be improved in this way.

[0037] In one embodiment, an optical waveguide opening is formed in an outer end face of the first coupling part and the optical waveguide is inserted into the optical waveguide opening such that the optical waveguide extends to the outer end face of the first coupling part.

[0038] In one embodiment, an optical fiber opening is formed in an outer end face of the second coupling part, and the signal processing module optical fiber is inserted into the optical fiber opening such that the optical fiber extends to the outer end face of the second coupling part.

[0039] When the optical fibers in the optical fiber openings of the first and second coupling parts each extend to an outer end face of the respective coupling part, the end faces of the two optical fibers are directly opposite each other when the two coupling parts are coupled together. This enables a very efficient and low-loss transmission of light signals between the two optical fibers. Furthermore, this allows for a compact coupling device that does not significantly increase the dimensions of the combination sensor in the longitudinal direction.

[0040] In one embodiment, the coupling device has a length of no more than 30 mm in the longitudinal direction. The coupling device can, in particular, have a length in the range between 20 mm and 25 mm in the longitudinal direction.

[0041] The first coupling part can have a length of not more than 15 mm in the longitudinal direction, in particular a length in the range of 11 mm to 13 mm.

[0042] The second coupling part may have a length of not more than 15 mm in the longitudinal direction, in particular a length in the range of 8 mm to 12 mm.

[0043] In one embodiment, the reference half-cell extends parallel to the measuring half-cell in the longitudinal direction through the measuring module. The reference chamber of the reference half-cell extends, in particular, parallel to the measuring chamber of the measuring half-cell. The diaphragm can be located at the distal end of the measuring module in fluid communication with the reference chamber.

[0044] In one embodiment, the diaphragm is formed at the distal end of the reference half-cell, in particular at a distal end face or at the periphery near the distal end of the reference half-cell, such that it establishes an electrical contact between the reference electrolyte and the liquid to be analyzed.

[0045] The diaphragm is designed in such a way that the electrochemical potential at the reference electrode is independent of the concentration of hydrogen ions in the liquid to be analyzed. The diaphragm can, in particular, have a porous structure.

[0046] In one embodiment, the first coupling part and the second coupling part of the coupling device are configured to establish an electrical connection between the reference electrode and at least one electronic component in the signal processing module. This enables the signal processing module to determine the electrical potential between the measuring half-cell and the reference electrode.

[0047] The pH value of the liquid to be analyzed can be determined based on the electrical potential that develops between the measuring electrode in the measuring half-cell and the reference electrode in the reference half-cell when the distal end of the measuring module is placed in the liquid to be analyzed.

[0048] Details on the operation of pH sensors comprising two half-cells are described, for example, in the document DE 10 2014 109 995 A1 and in the textbook “pH-Messung” by Helmuth Galster, Wiley-VCH, 1990, ISBN 23527278362.

[0049] In one embodiment, the measuring module additionally comprises an electrical temperature sensor. The electrical temperature sensor can be arranged, in particular, at the distal end or at the distal end face of the measuring module in order to measure the temperature of the liquid to be analyzed when the distal end of the measuring module is arranged in the liquid to be analyzed.

[0050] In this case, the coupling device is also designed to transmit electrical signals provided by the electrical temperature sensor from the measuring module to the signal processing module when the first coupling part and the second coupling part are coupled to one another. The signal processing module is thus able to evaluate the electrical signals provided by the electrical temperature sensor in order to determine the temperature of the liquid to be analyzed. The first coupling part and the second coupling part can, in particular, have additional electrical contacts that enable the electrical signals provided by the electrical temperature sensor to be transmitted from the measuring module to the signal processing module.

[0051] The electrical temperature sensor can be, for example, an NTC sensor or a PTC sensor.

[0052] In one embodiment, a shielding element is arranged between the measuring module housing and the first coupling part, which electromagnetically shields the coupling device. The shielding element can be made of metal, for example, stainless steel.

[0053] In one embodiment, the shielding element is tubular, and the first coupling part and the second coupling part are arranged in the tubular shielding element when the first coupling part and the second coupling part are coupled to each other.

[0054] In one embodiment, at least one sealing element, in particular at least one sealing ring, is provided between the measuring module housing and the shielding element.

[0055] In one embodiment, at least one sealing element, in particular at least one sealing ring, is arranged between the signal processing module housing and the shielding element.

[0056] In one embodiment, at least one sealing element, in particular a sealing ring, is arranged between the shielding element and at least one of the two coupling parts. Such sealing elements can reliably prevent unwanted penetration of fluid into the measuring module and / or the signal processing module.

[0057] In one embodiment, at least one support element is provided in the measuring module housing for supporting the optical fiber, the measuring half-cell, the reference half-cell, and / or any temperature sensor present. The at least one support element can be fixed in the measuring module housing.

[0058] In one embodiment, a first, distal support element is provided in the measuring module housing at an end facing the first coupling part and a second, proximal support element is provided at an end facing away from the first coupling part.

[0059] Such support elements allow the optical fiber, the measuring half-cell, the reference half-cell, and / or any temperature sensor to be securely supported and secured within the measuring module housing. This significantly reduces the risk of mechanical damage to the optical fiber, the measuring half-cell, the reference half-cell, and any temperature sensor.

[0060] In one embodiment, at least one sealing element, in particular at least one sealing ring, is provided between the measuring module housing and the at least one support element in order to prevent fluid from penetrating into the interior of the measuring module.

[0061] In the following, an embodiment of a combination sensor designed according to the invention is described with reference to the attached figures.

[0062] Figure 1 shows a schematic view of a system for determining the pH value and the oxygen content of a liquid according to an embodiment of the invention.

[0063] Figure 2A shows a sectional view of a combination sensor with a measuring module and a signal processing module according to an embodiment of the invention in an assembled state.

[0064] Figure 2B shows a sectional view of the combination sensor shown in Figure 2A, with the measuring module and the signal processing module separated from each other.

[0065] Figure 3 shows an enlarged perspective view of the distal end of the measuring module facing away from the signal processing module.

[0066] Figure 4 shows an enlarged perspective sectional view of the mutually facing end regions of the measuring module and the signal processing module of a combination sensor designed according to the invention.

[0067] Figure 5 shows a perspective view of a first coupling part of a combination sensor designed according to the invention.

[0068] Figure 6 shows a perspective view of a second coupling part of a combination sensor designed according to the invention. Figure 1 shows a schematic view of a system 1 for determining the pH value and the oxygen content of a liquid 5 according to an embodiment of the invention.

[0069] The liquid 5, whose pH and oxygen content are to be determined, is located in a reactor 3, in particular in a bioreactor 3.

[0070] The system 1 comprises a combination sensor 2 which extends from the outside into the interior of the reactor 3 in such a way that a distal end 2a of the rod-shaped combination sensor 2 is arranged within the liquid 5.

[0071] The combination sensor 2 is coupled to an evaluation device 7 arranged outside the reactor 3, which is designed to evaluate signals provided by the combination sensor 2 in order to determine the pH value and the oxygen content of the liquid 5.

[0072] The signals can be transmitted as electrical signals via a cable connection 9 from the combination sensor 2 to the evaluation device 7, as shown in Figure 1.

[0073] In an alternative embodiment, the signals can be transmitted wirelessly, for example via a WLAN data connection or a Bluetooth data connection, from the combination sensor 2 to the evaluation device 7.

[0074] Figure 2A shows a sectional view of a combination sensor 2 according to an embodiment of the invention with a measuring module 4 and a signal processing module 6 in an assembled state.

[0075] Figure 2B shows a sectional view of the combination sensor 2 in which the measuring module 4 and the signal processing module 6 are separated from each other.

[0076] Figure 3 shows an enlarged perspective view of the distal end 4a of the measuring module 4 of the combination sensor 2, facing away from the signal processing module 6.

[0077] The measuring module 4 is essentially cylindrical and extends in a longitudinal direction L. A so-called single-rod measuring chain for determining the pH value of the liquid 5 to be analyzed is formed in the measuring module 4. The single-rod measuring chain comprises a measuring half-cell 50 and a reference half-cell 60. The measuring half-cell 50 and the reference half-cell 60 are also essentially cylindrical and also extend in the longitudinal direction L. The measuring half-cell 50 is arranged within the reference half-cell 60.

[0078] The two half-cells 50, 60 of the combination electrode together form a pH sensor, which makes it possible to determine the pH value of the liquid 5 to be analyzed.

[0079] The measuring module 4 has a measuring module housing 45 that defines and encloses or forms the reference half-cell 60. The measuring module housing 45 can be made of plastic.

[0080] The reference half-cell 60 comprises a reference chamber 62 filled with a suitable reference electrolyte. The measuring module housing 45 can, in particular, be designed as a housing for the reference chamber 62. A reference electrode, not visible in the figures, is located in the reference chamber 62 of the reference half-cell 60.

[0081] Figure 3 shows that a diaphragm 66 is provided at a distal end of the reference chamber 62, which is shown on the right side in Figures 2A, 2B, and 3. The diaphragm 66 is designed to establish electrical contact between the reference electrolyte in the reference chamber 62 and the liquid 5 to be analyzed. The electrochemical potential at the reference electrode is independent of the concentration of hydrogen ions in the liquid 5 to be analyzed.

[0082] The measuring half-cell 50 is formed within the reference chamber 62 of the reference half-cell 60. The measuring half-cell 50 has a measuring chamber 52 filled with a suitable measuring electrolyte. A measuring electrode 54 extends in the longitudinal direction L through the measuring chamber 52. The measuring electrolyte in the measuring chamber 52 is an electrolyte solution that acts as an internal buffer.

[0083] At a distal end of the measuring chamber 52, a measuring membrane 56 is provided, which can be seen in Figure 3. The measuring membrane 56 establishes an electrical contact between the measuring electrolyte in the measuring chamber 52 and the liquid 5 to be analyzed when the distal end 2a of the combination sensor 2 is arranged in the liquid 5 to be analyzed, as shown in Figure 1.

[0084] The measuring membrane 56 is particularly constructed such that an electrochemical potential at the measuring electrode 54 changes depending on the concentration of hydrogen ions in the liquid 5 to be analyzed. The measuring membrane 56 can, for example, be part of a glass electrode. The glass electrode can, in particular, be made of PHI glass.

[0085] The pH value of the liquid 5 to be analyzed can be determined based on the electrical potential that develops between the measuring electrode 54 in the measuring half-cell 50 and the reference electrode in the reference half-cell 60 when the distal ends of the measuring half-cell 50 and the reference half-cell 60 with the measuring membrane 56 and the diaphragm 66 are arranged in the liquid 5 to be analyzed.

[0086] Details of the operation of pH sensors formed with two half-cells 50, 60 as previously described are described, for example, in the document DE 10 2014 109 995 A1 and in the textbook “pH-Messung” by Helmuth Galster, Wiley-VCH, 1990, ISBN 23527278362.

[0087] In addition to the measuring half-cell 50, at least one optical waveguide 40 extends in the longitudinal direction L through the reference chamber 62 of the reference half-cell 60.

[0088] The optical waveguide 40 is designed such that a distal end region 40a of the optical waveguide 40, which is located at the distal end 4a of the measuring module 4 shown in an enlarged view in Figure 3, is in contact with the liquid 5 to be analyzed. The optical waveguide 40 has, in particular, a light input surface 40b shown in Figure 3, which is formed on or in an end face at the distal end region 40a of the optical waveguide 40.

[0089] The optical waveguide 40 is provided with a fluorescent dye that interacts with light irradiated into the optical waveguide 40. In particular, the light input surface 40b at the distal end region 40a of the optical waveguide 40 can be coated with the fluorescent dye. An optical waveguide 40 interacting with a fluorescent dye makes it possible to optically determine the oxygen content of the liquid 5 to be analyzed. The oxygen content of the liquid 5 to be analyzed can be determined, in particular, based on a wavelength shift and / or a phase shift of light emitted by the fluorescent dye.

[0090] The optical waveguide 40 has a transparent core, in particular a glass core. The transparent core of the optical waveguide 40 can be encased in a cylindrical jacket to mechanically stabilize the transparent core of the optical waveguide 40 and protect it from harmful external influences, in particular from harmful mechanical influences. The jacket can prevent or at least reduce a loss or attenuation of the light signals in the optical waveguide. The optical waveguide 40 can be encased in a material, for example, stainless steel or a suitable plastic, that is inert to the electrolyte in the reference half-cell 60.

[0091] The measuring module 4 also has an electrical temperature sensor 70, which is formed in particular at the distal end 4a of the measuring module 4, which is shown in Figure 3. The electrical temperature sensor 70 is intended and designed to provide electrical signals that make it possible to determine the temperature of the liquid 5 to be analyzed. The electrical temperature sensor 70 can, in particular, be an NTC sensor or a PTC sensor.

[0092] In the measuring module housing 45, two essentially cylindrical support elements 49a, 49b are provided, which support and fix the optical waveguide 40, the measuring half-cell 50 and the optionally present electrical temperature sensor 70 on the wall of the reference half-cell 60 or the measuring module housing 45.

[0093] The measuring module 4 has, in particular, a first, proximal support element 49a and a second, distal support element 49b. The proximal support element 49a is arranged on the proximal side facing the signal processing module 6 in the measuring module housing 45 of the measuring module 4 and supports the proximal ends of the measuring half-cell 50 and the optical fiber 40. The distal support element 49b is arranged on the distal side facing away from the signal processing module 6 in the measuring module housing 45 of the measuring module 4 and supports the distal ends of the measuring half-cell 50 and the optical fiber 40. More than the two support elements 49a, 49b shown in Figures 1 and 2 can also be provided.

[0094] The support elements 49a, 49b can be made of plastic.

[0095] Sealing rings 97, which can be designed in particular as O-rings, are provided between the support elements 49a, 49b and the measuring half-cell 50.

[0096] Sealing rings 99, in particular O-rings, are provided between the support elements 49a, 49b and the wall of the reference half-cell 60 or the measuring module housing 45.

[0097] Through the interaction of the support elements 49a, 49b with the sealing rings 97, 99, the reference half-cell 60 is fluid-tightly sealed both at its distal end, which is introduced into the liquid 5 to be analyzed for the measurement, and at its proximal end, which faces the coupling device 8 and the signal processing module 6. This reliably prevents unwanted penetration of the liquid 5 to be analyzed into the reference half-cell 60.

[0098] The signal processing module 6 contains several electronic components 41, 42, 44.

[0099] The signal processing module 6 contains, among other things, an electrical light source 41, in particular an LED, which is provided and designed to radiate light into the optical waveguide 40 during operation. The electrical light source 41 can, in particular, be designed to emit light suitable for optically exciting the fluorescent dye that interacts with the optical waveguide 40 in the measuring module 4.

[0100] The electric light source 41 can, for example, be designed to generate light with a wavelength in the range of 400 nm to 500 nm, in particular light with a wavelength of 450 nm, and to radiate it into the optical waveguide.

[0101] Also located in the signal processing module 6 is an electrical light detector 42, for example, a photodiode. The light detector 42 is provided and configured to detect light supplied to the signal processing module 6 through the optical fiber 40. A light filter 43 can be provided in front of the light detector 42. The light filter 43 can be configured to be transparent to light with wavelengths in a range of 750 nm to 880 nm and to block light outside this wavelength range.

[0102] An optical system, for example at least one lens, can be located between the optical waveguide 40 and the light detector 42 in order to bundle or focus the light emerging from the optical waveguide 40 onto the light detector 42.

[0103] The signal processing module 6 comprises further electronic components 44, e.g., resistors, capacitors, diodes, transistors, and / or integrated electronic semiconductor circuits, which are designed to evaluate the electrical signals provided by the light detector 42 in order to determine the oxygen content of the liquid 5 to be analyzed. The electronic components 44 can also comprise at least one programmable microprocessor for this purpose.

[0104] The signal processing module 6 also includes electronic components 44 designed to evaluate electrical signals provided by the electrodes in the two half-cells 50, 60 in order to determine the pH value of the liquid 5 to be analyzed.

[0105] The signal processing module 6 can also have electronic components 44 which are intended to control the electrical temperature sensor 70 and to evaluate the electrical signals provided by the electrical temperature sensor 70 in order to determine the temperature of the liquid 5 to be analyzed.

[0106] The signal processing module 6 can also include electronic components 44 that form a data transmission unit that enables signals to be transmitted wirelessly, for example, via a cable connection 9, via a WLAN data connection, or via a Bluetooth data connection, from the signal processing module 6 to the evaluation device 7. The light source 41, the light detector 42, and the electronic components 44 can be arranged within the signal processing module 6 on one or more circuit boards 46, in particular on printed circuit boards.

[0107] The measuring module 4 and the signal processing module 6 can be connected to each other, as shown in Figure 2A, to provide a functional combination sensor 2. However, the measuring module 4 and the signal processing module 6 can also be separated from each other, as shown in Figure 2B.

[0108] The ability to separate the measuring module 4 and the signal processing module 6 from one another makes it possible to separate the wear-prone measuring module 4, which generally has a shorter service life than the signal processing module 6, from the signal processing module 6 and replace it when it has reached the end of its service life. The more durable signal processing module 6 can thus be coupled and operated sequentially with a plurality of measuring modules 4. As a result, the expensive and durable electronic components contained in the signal processing module 6 do not have to be replaced each time a measuring module 4 reaches the end of its service life. The operating costs of a combination sensor 2 according to the invention can thus be significantly reduced by repeatedly replacing the measuring module 4 and continuing to use the signal processing module 6.

[0109] In order to couple the measuring module 4 and the signal processing module 6 to form a functional combination sensor 2, a coupling device 8 is provided.

[0110] The coupling device 8 comprises a first coupling part 81, which is provided on or in the measuring module 4, and a complementary second coupling part 82, which is provided on or in the signal processing module 6.

[0111] The first coupling part 81 and the second coupling part 82 can be coupled together, as shown in Figure 2A. They can also be separated from each other again, as shown in Figure 2B.

[0112] When the first coupling part 81 and the second coupling part 82 are coupled to one another, the coupling device 8 is designed to transmit light emitted by the light source 41 into the optical fiber 40 in the measuring module 4 and to transmit light from the optical fiber 40 to the signal processing module 6 in such a way that it can be detected by the light detector 42.

[0113] When the first coupling part 81 and the second coupling part 82 are coupled to one another, as shown in Figure 2A, the coupling device 8 is further configured to transmit electrical signals provided by the measuring electrode 54 and the reference electrode of the half-cells 50, 60 in the measuring module 4 to a data transmission unit and / or an optional evaluation unit in the signal processing module 6. The evaluation unit can, in particular, be configured to determine the pH value of the liquid 5 to be analyzed based on the provided electrical signals.

[0114] The data transmission unit can be configured to transmit the signals provided by the measuring module 4 and / or the optional evaluation unit to the evaluation device 7, for example, to a computer. The data transmission unit can, in particular, be configured to transmit the signals provided by the measuring module 4 and / or the optional evaluation unit to the evaluation device 7 via a cable connection or wirelessly.

[0115] The first coupling part 81 and the second coupling part 82 are designed such that they can be coupled and separated from each other without tools.

[0116] The first coupling part 81 and the second coupling part 82 can in particular be designed such that they can be coupled to one another by means of a plug connection, a screw connection, a bayonet connection and / or a snap-in connection.

[0117] Figure 4 shows, in an enlarged perspective sectional view, the mutually facing end regions of the measuring module 4 and the signal processing module 6 of a combination sensor 2 designed according to the invention with a coupling device 8. The first coupling part 81 and the second coupling part 82 of the coupling device 8 are separated from one another.

[0118] Figure 5 shows a perspective view of the first coupling part 81 and Figure 6 shows a perspective view of the second coupling part 82. In the embodiment shown in the figures, the first coupling part 81 is designed as a plug, and the second coupling part 82 is designed as a socket.

[0119] In alternative embodiments not explicitly shown in the figures, the first coupling part 81 may be socket-like and the second coupling part 82 may be plug-like.

[0120] Mixed forms are also possible in which both the first coupling part 81 and the second coupling part 82 have plug-like protruding areas and / or elements, and socket-like areas, e.g. hollow areas, which are provided for receiving the plug-like areas of the respective other coupling part 81, 82.

[0121] In the embodiment shown in the figures, the first coupling part 81 is disc-shaped or cylindrical with a circular cross-section.

[0122] The first coupling part 81 can, for example, have a diameter in the range of 8 mm to 12 mm and a thickness in the range of 3 mm to 7 mm, in particular a thickness between 4 mm and 6 mm.

[0123] On an end face 81a of the first coupling part 81, which in the coupled state of the coupling device 80 faces away from the second coupling part 82, as shown in Figure 4, a collar 83 is formed which extends approximately semicircularly along the edge of the first coupling part 81.

[0124] The collar 83 can, for example, extend over a length in the range of 6 mm to 8 mm from the end face 81a of the first coupling part 81 in the direction of the distal end of the measuring module 4.

[0125] Below the collar 83, an optical fiber opening 85 is formed, which is provided for receiving the optical fiber 40 such that the coated glass core of the optical fiber 40, as shown in Figure 4, extends directly to an opposite end face of the first coupling part 81 (not visible in Figure 5), which, when the coupling device 8 is coupled, faces the second coupling part 82. A plurality of electrical contacts 87 are located below the optical fiber opening 85. In the exemplary embodiment shown in the figures, the electrical contacts 87 protrude from the surface of the first coupling part 81 in the form of metallic contact pins. Alternatively or additionally, the electrical contacts 87 can also be designed, at least in part, as sockets for receiving corresponding contact pins protruding from the second coupling part 82.

[0126] In the embodiment of the first coupling part 81 shown in Figure 5, four electrical contacts 87 are arranged in a semicircle below the optical fiber opening 85. Other geometric arrangements of the electrical contacts 87, each of which may comprise more or fewer than four electrical contacts 87, are also possible.

[0127] Below the electrical contacts 87, a bore 89 is formed, which is intended to receive a centering and fixing pin 90 formed on the signal processing module 6 (see Figures 1, 2 and 4) when the first coupling part 81 is joined to the second coupling part 82. The bore 89 can have a conical edge, which guides the centering and fixing pin 90 into the bore 89 when the two coupling parts 81, 82 are joined together.

[0128] The second coupling part 82 shown in Figure 6 is cylindrical, in particular with a substantially circular cross-section. The second coupling part 82 has an outer end face 82a, which faces the first coupling part 81 when the second coupling part 82 is coupled to the first coupling part 81.

[0129] The second coupling part 82 can, for example, have a diameter in the range of 4 mm to 10 mm, in particular a diameter in the range of 6 mm to 8 mm, and a length in the range of 8 mm to 15 mm, in particular a length in the range of 10 mm to 12 mm.

[0130] An optical fiber opening 84 is formed in the second coupling part 82, which is provided for receiving a signal processing module optical fiber 93 such that the glass core of the signal processing module optical fiber 93 extends directly to the outer end face 82a of the second coupling part 82, which faces the first coupling part 81 when the two coupling parts 81, 82 are coupled to one another.

[0131] The signal processing module optical fiber 93 can be seen in Figures 2A, 2B and 4.

[0132] The signal processing module optical fiber 93 is split outside the second coupling part 82 into a first optical fiber strand 91 and a second optical fiber strand 92.

[0133] The first optical fiber strand 91 of the signal processing module optical fiber 93 is designed to guide light from the light source 41 to the second coupling part 82. Thus, when the first coupling part 81 and the second coupling part 82 are coupled together, as shown in Figure 2A, the light from the light source 41 can be transmitted into the optical fiber 40 of the measuring module 4, which is arranged in the optical fiber opening 85 of the first coupling part 81.

[0134] The second optical fiber strand 92 of the signal processing module optical fiber 93 is configured to guide light transmitted from the optical fiber 40 of the measuring module 4 to the first coupling part 81, from the second coupling part 82 to the light detector 42. Thus, the light from the optical fiber 40 of the measuring module 4 can be detected by the light detector 42 in the signal processing module 6 when the first coupling part 81 and the second coupling part 82 are coupled to one another, as shown in Figure 2A.

[0135] When the optical fibers 40, 93 extend in the optical fiber openings 84, 85 of the first and second coupling parts 81, 82 each to an outer end face 82a of the respective coupling part 81, 82, as previously described, the end faces of the two optical fibers 40, 93 are directly opposite one another when the two coupling parts 81, 82 are coupled together. This enables a very efficient and low-loss transmission of light signals between the two optical fibers 40, 93.

[0136] The optical waveguides 40, 93 can, in particular, be arranged in the optical waveguide openings 84, 85 of the first and second coupling parts 81, 82 such that they touch each other when the two coupling parts 81, 82 are coupled together. In this way, unwanted light leakage at the optical interface 84, 85 between the two optical waveguides 40, 93 can be further reduced.

[0137] Although in Figures 5 and 6 only a single optical fiber opening 84,

[0138] 85, the coupling parts 81, 82 of coupling devices 80 according to the invention can also have two or more optical waveguide openings 84, 85, which are designed such that they lie opposite one another when the two coupling parts 81, 82 are coupled together. In this way, a plurality of optical waveguides 40, 93 can be optically coupled to one another using the coupling device 80.

[0139] Below the optical fiber opening 84, a plurality of electrical contacts 86 are provided in the outer end face 82a of the second coupling part 82, which electrical contacts are designed to make contact with the electrical contacts 87 of the first coupling part 81.

[0140] In the embodiment shown in Figure 6, the electrical contacts

[0141] 86 in the outer end face 82a of the second coupling part 82 as sockets for receiving corresponding contact pins 87, which are present on the first coupling part 81.

[0142] Alternatively or additionally, the electrical contacts 86 of the second coupling part 82 can also be formed at least partially as metallic contact pins which protrude from the outer end face 82a of the second coupling part 82 and are received by corresponding sockets (not shown in the figures) formed in the first coupling part 81 when the first coupling part 81 and the second coupling part 82 are coupled to one another.

[0143] The optical waveguide openings 84, 85 and the electrical contacts 86, 87 in the first coupling part 81 and in the second coupling part 82 are designed to correspond so that they lie opposite one another in pairs when the first coupling part 81 and the second coupling part 82 are coupled to one another.

[0144] The two optical fiber openings 84, 85 with the optical fibers 40, 93 arranged therein thus form an optical interface 84, 85 for transmitting light signals between the optical fibers 40, 93. The electrical contacts 86, 87 form electrical connections for transmitting electrical signals between the measuring module 4 and the signal processing module 6.

[0145] The second coupling part 82, which is formed on the signal processing module 6, has at least as many electrical contacts 87 as the first coupling part 81, which is formed on the measuring module 4, so that each of the electrical contacts 87 of the first coupling part 81 is received by an electrical contact 86 of the second coupling part 82 when the first coupling part 81 and the second coupling part 82 are coupled to one another.

[0146] The second coupling part 82 can also have more electrical contacts 86 than the first coupling part 81. The excess electrical contacts 86 can remain unused when the two coupling parts 81, 82 are coupled. For example, the second coupling part 82 can have electrical contacts 86 for contacting an electrical temperature sensor 70, which remain unused when the signal processing module 6 is coupled to a measuring module 4 that is not equipped with an electrical temperature sensor 70.

[0147] The first coupling part 81 and the second coupling part 82 can each be made of plastic. The first coupling part 81 and the second coupling part 82 can be made of the same materials, in particular the same plastic, or of different materials or plastics.

[0148] In the embodiment shown in the figures, the signal processing module 6 is arranged in a cylindrical projection 63, which protrudes in the direction of the measuring module 4 from the side of the signal processing module 6 facing the measuring module 4. The second coupling part 82 is arranged in a cavity formed in the projection 63.

[0149] The centering and fixing pin 90 is fixed in a bore formed in the cylindrical projection 63.

[0150] A sealing ring 64, in particular an O-ring, is provided around the projection 63, which seals the interface between the measuring module 4 and the signal processing module 6 in a fluid-tight manner when coupled. In further embodiments not explicitly shown in the figures, several sealing rings 64 may also be present, and / or sealing elements may be provided on the outer end face 82a of the second coupling part 82.

[0151] In further embodiments, which are not explicitly shown in the figures, the measuring module 4 can also have a projection, and / or sealing elements, in particular sealing rings 64, can be provided on the measuring module 4.

[0152] A shielding element 94 is provided around the first coupling part 81 in the measuring module 4 and is designed to shield the coupling device 8 from external electromagnetic influences. The shielding element 94 is particularly designed such that it also extends around the second coupling part 82 when the first and second coupling parts 81, 82 are coupled to one another, as shown in Figure 2A.

[0153] The shielding element 94 can in particular be designed as a tube or sleeve which, in the coupled state of the coupling device 8, encloses the first coupling part 81 and the second coupling part 82 and thus shields them.

[0154] The shielding element 94 can be made of metal, for example stainless steel.

[0155] The shielding element 94 is sealed from the measuring module housing 45 by at least one sealing ring 96, in particular an O-ring, which is located between the shielding element 94 and the measuring module housing 45.

[0156] In embodiments not shown in the figures, a shielding element 94 may alternatively or additionally be formed on the second coupling part 82.

[0157] In the embodiment shown in the figures, the shielding element 94 is at least partially enclosed by the handle element 95.

[0158] On the distal side of the collar 47 facing away from the handle element 95, a sealing ring 98, in particular an O-ring, can be provided, which is intended to seal the measuring module 4 against a reactor 3 not shown in the figures when the measuring module 4 is inserted into a reactor 3 during operation in order to measure the oxygen content and / or the pH value and / or the temperature of a liquid 5 in the reactor 3.

Claims

Patent claims 1. Combination sensor (2) for determining the pH value and oxygen content of a liquid (5) to be analyzed, in particular in a bioreactor (3), the combination sensor (2) comprising: a measuring module (4) which has at least one optical fiber (40) and a single-rod measuring chain with a reference half-cell (60) and a measuring half-cell (50), the at least one optical fiber (40) and the measuring half-cell (50) being arranged within the reference half-cell (60);a signal processing module (6) with electronic components (41, 42, 44) designed to convert light signals transmitted through the at least one optical waveguide (40) into electrical signals, to enable the oxygen content of the liquid (5) to be analyzed to be determined from the light signals transmitted through the at least one optical waveguide (40), and to process electrical signals provided at a measuring electrode (54) to enable the pH value of the liquid (5) to be analyzed to be determined from the electrical signals provided at the measuring electrode (54); and a coupling device (8) with a first coupling part (81) provided on the measuring module (4) and a complementary second coupling part (82) provided on the signal processing module (6), wherein the first coupling part (81) and the second coupling part (82) can be detachably coupled to one another;wherein the coupling device (8) is designed to transmit light signals transmitted through the at least one optical waveguide (40) and electrical signals provided at the measuring electrode (54) from the measuring module (4) to the signal processing module (6) when the first coupling part (81) and the second coupling part (82) are coupled to one another; 2. Combination sensor (2) according to claim 1, wherein the first coupling part (81) and the second coupling part (82) are coupled to one another in such a way that they can be detached from one another without tools.

3. Combination sensor (2) according to claim 1 or 2, wherein the measuring module (4) and the signal processing module (6) are coupled to one another by a plug connection, a screw connection, a bayonet connection and / or a snap-in connection.

4. Combination sensor (2) according to one of the preceding claims, wherein the measuring module (4) and the signal processing module (6) are designed such that the combination sensor (2) is fluid-tightly sealed in the coupled state.

5. Combination sensor (2) according to one of the preceding claims, wherein the first coupling part (81) and the second coupling part (82) each have a plurality of electrical contacts (86, 87) for transmitting the electrical signals between the measuring module (4) and the signal processing module (6) and at least one optical interface (84, 85) for transmitting the light signals, wherein the electrical contacts (86, 87) are arranged in particular around the at least one optical interface (84, 85).

6. Combination sensor (2) according to one of the preceding claims, wherein the at least one optical waveguide (40) has a core coated with stainless steel or plastic, wherein the core of the at least one optical waveguide (40) is in particular a glass core.

7. Combination sensor (2) according to one of the preceding claims, wherein the measuring module (4) extends in a longitudinal direction (L), wherein in particular the at least one optical waveguide (40), the reference half-cell (60) and the measuring half-cell (50) extend in the longitudinal direction (L), wherein the first coupling part (81) and the second coupling part (82) can be connected to and separated from one another by a movement which comprises a movement component in the longitudinal direction (L).

8. Combination sensor (2) according to claim 1, wherein the at least one optical waveguide (40) extends in the longitudinal direction (L) through the reference half-cell (60).

9. Combination sensor (2) according to claim 7 or 8, wherein the coupling device (8) has a length of not more than 30 mm in the longitudinal direction (L), wherein the coupling device (8) in the longitudinal direction (L) in particular has a length in the range of 20 mm to 25 mm.

10. Combination sensor (2) according to one of claims 7 to 9, wherein the first coupling part (81) has a length of not more than 15 mm in the longitudinal direction (L), wherein the first coupling part (81) in the longitudinal direction (L) has in particular a length in the range from 11 mm to 13 mm, and / or wherein the second coupling part (82) has a length of not more than 15 mm in the longitudinal direction (L), wherein the second coupling part (82) in the longitudinal direction (L) has in particular a length in the range from 8 mm to 12 mm.

11. Combination sensor (2) according to one of the preceding claims, wherein an optical waveguide opening (85) is formed in an outer end face of the first coupling part (81), and wherein the optical waveguide (40) is introduced into the optical waveguide opening (85) in such a way that the optical waveguide (40) extends to the outer end face of the first coupling part (8).

12. Combination sensor (2) according to one of the preceding claims, wherein the at least one optical waveguide (40) is provided with a fluorescent dye which interacts with light radiated into the optical waveguide (40).

13. Combination sensor (2) according to claim 12, wherein the at least one optical waveguide (40) has a light input surface (40b) coated with the fluorescent dye, which is formed on or in an end face at the distal end (4a) of the measuring module (4), so that the fluorescent dye is in contact with the liquid (5) to be analyzed when the measuring module (4) is arranged in the liquid (5) to be analyzed.

14. Combination sensor (2) according to one of the preceding claims, wherein the reference half-cell (60) is a reference chamber filled with a reference electrolyte (62) with a reference electrode and a diaphragm (66), wherein the diaphragm (66) is designed such that it establishes an electrical contact between the reference electrolyte and the liquid to be analyzed (5).

15. Combination sensor (2) according to one of the preceding claims, wherein the measuring module (4) has a measuring module housing (45) which encloses and / or forms the reference half-cell (60), wherein the measuring module housing (45) is preferably made of plastic.

16. Combination sensor (2) according to claim 15, wherein a shielding element (94), in particular a shielding element (94) made of metal, is arranged between the measuring module housing (45) and the first coupling part (81).

17. Combination sensor (2) according to claim 16, wherein a first sealing element (96), in particular a first sealing ring (96), is arranged between the measuring module housing (45) and the shielding element (94); and / or wherein a second sealing element (64), in particular a second sealing ring (64), is arranged between the first coupling part (81) and the shielding element (94).

18. Combination sensor (2) according to one of the preceding claims, wherein a light source (41) is provided in the signal processing module (6), which is designed to radiate light into the at least one optical waveguide (40), wherein the coupling device (8) is designed in particular to transmit light emitted by the light source (41) to the measuring module (4) in such a way that the light reaches the at least one optical waveguide (40).

19. Combination sensor (2) according to one of the preceding claims, wherein a light detector (42) is provided in the signal processing module (6), which is designed to detect light that is supplied to the light detector (42) through the at least one optical waveguide (40), wherein the coupling device (8) is designed in particular to transmit the light from the at least one optical waveguide (40) to the light detector (42).

20. Combination sensor (2) according to claim 19, wherein a light filter (43) is provided in front of the light detector (42), wherein the light filter (43) is transparent in particular for light with wavelengths in a range from 750 nm to 880 nm.

21. Combination sensor (2) according to one of claims 18 to 20, wherein the signal processing module (6) has at least one signal processing module optical waveguide (93) extending from the second coupling part (82) to the light source (41) and / or to the light detector (42).

22. Combination sensor (2) according to claim 21, wherein an optical fiber opening (84) is formed in an outer end face (82a) of the second coupling part (82), and wherein the signal processing module optical fiber (93) is introduced into the optical fiber opening (84) such that the signal processing module optical fiber (93) extends to the outer end face (82a) of the second coupling part (82).

23. Combination sensor (2) according to claim 21 or 22, wherein the signal processing module optical waveguide (93) is split outside the second coupling part (82) into a first optical waveguide strand (91) and a second optical waveguide strand (92), wherein the first optical waveguide strand (91) extends from the second coupling part (82) to the light source (41), and wherein the second optical waveguide strand (92) extends from the second coupling part (82) to the light detector (42).

24. Combination sensor (2) according to one of the preceding claims, wherein the measuring module (4) additionally has an electrical temperature sensor (70) and wherein the coupling device (8) is designed to transmit electrical signals provided by the electrical temperature sensor (70) from the measuring module (4) to the signal processing module (6) when the first coupling part (81) and the second coupling part (82) are coupled to one another, wherein the temperature sensor (70) is in particular an NTC sensor or a PTC sensor.

25. Combination sensor (2) according to one of the preceding claims, wherein at least one support element (49a, 49b) is present in the reference half-cell (60) in order to support the measuring half-cell (50) and / or the at least one optical waveguide (40) in the reference half-cell (60).

26. Combination sensor (2) according to claim 25, wherein in the reference half-cell (60) at an end facing the first coupling part (81) there is a distal support element (49a) for supporting a distal end of the measuring half-cell (50) and / or a distal end of the optical waveguide (40) and wherein in the measuring half-cell (50) at an end facing away from the first coupling part (81) there is a proximal support element (49a) for supporting a proximal end of the measuring half-cell (50) and / or a proximal end of the optical waveguide (40).

27. Combination sensor (2) according to one of claims 25 or 26, wherein at least one third sealing element (99), in particular at least one sealing ring (99), is provided between the measuring module housing (45) and the at least one support element (49a, 49b).

28. System (1) for determining the pH value and oxygen content of a liquid (5) to be analyzed, the system (1) comprising: a combination sensor (2) according to one of the preceding claims, and an evaluation device (7), in particular a computer, the evaluation device (7) being designed to process signals provided by the signal processing module (6) in order to determine and / or display the pH value of the liquid (5) to be analyzed.

29. System according to claim 28, wherein the signal processing module (6) and the evaluation device (7) are designed to wirelessly transmit the signals provided by the signal processing module (6) to the evaluation device (7).

30. Measuring module (4) for a combination sensor (2) for determining the pH value and oxygen content of a liquid (5) to be analyzed, in particular in a bioreactor (3), wherein the measuring module (4) comprises at least one optical fiber (40) and a single-rod measuring chain with a reference half-cell (60) and a measuring half-cell (50), wherein the at least one optical waveguide (40) and the measuring half-cell (50) are arranged within the reference half-cell (60); wherein the measuring module (4) has a first coupling part (81) which is detachably connectable to a complementary second coupling part (82), wherein the first coupling part (81) is connected to the at least one optical waveguide (40) and a measuring electrode (54) and is designed to transmit light signals transmitted by the at least one optical waveguide (40) and electrical signals provided at the measuring electrode (54) to the complementary second coupling part (82) when the first coupling part (81) and the second coupling part (82) are coupled to one another; wherein the complementary second coupling part (82) is in particular a coupling part (82) of a signal processing module (6) according to one of claims 46 to 54.

31. Measuring module (4) according to claim 30, with a measuring module housing (45) in which the measuring half-cell (50) is formed, wherein the measuring module housing (45) is made in particular of plastic.

32. Measuring module (4) according to claim 31, wherein a shielding element (94), in particular a shielding element (94) made of metal, is arranged between the measuring module housing (45) and the first coupling part (81).

33. Measuring module (4) according to claim 32, wherein a first sealing element (96), in particular a first sealing ring (96), is arranged between the measuring module housing (45) and the shielding element (94); and / or wherein a second sealing element (64), in particular a second sealing ring (64), is arranged between the first coupling part (81) and the shielding element (94).

34. Measuring module (4) according to one of claims 30 to 33, wherein at least one support element (49a, 49b) for supporting the at least one optical waveguide (40) and the measuring half-cell (50) is present in the measuring module housing (45).

35. Measuring module (4) according to claim 34, wherein at least one third sealing element (99), in particular at least one third sealing ring (99), is provided between the measuring module housing (45) and the at least one support element (49a, 49b).

36. Measuring module (4) according to one of claims 34 or 35, wherein in the measuring module housing (45) at an end facing the first coupling part (81) there is a distal support element (49a) for supporting a distal end of the measuring half-cell (50) and / or a distal end of the optical waveguide (40) and wherein in the measuring module housing (45) at an end facing away from the first coupling part (81) there is a proximal support element (49b) for supporting a proximal end of the measuring half-cell (50) and / or a proximal end of the optical waveguide (40).

37. Measuring module (4) according to one of claims 30 to 36, wherein the measuring module (4) extends in a longitudinal direction (L), wherein in particular the at least one optical waveguide (40), the reference half-cell (60) and the measuring half-cell (50) extend in the longitudinal direction (L), wherein the first coupling part (81) and the second coupling part (82) are connectable to and separable from one another by a movement comprising a movement component in the longitudinal direction (L).

38. Measuring module (4) according to claim 37, wherein the first coupling part (81) in the longitudinal direction (L) has a length of not more than 15 mm, wherein the first coupling part (81) in the longitudinal direction (L) in particular has a length in the range of 11 mm to 13 mm.

39. Measuring module (4) according to one of claims 30 to 38, wherein an optical waveguide opening (85) is formed in an outer end face of the first coupling part (81) and wherein the optical waveguide (40) is introduced into the optical waveguide opening (85) in such a way that the optical waveguide (40) extends to the outer end face of the first coupling part (8).

40. Measuring module (4) according to one of claims 30 to 39, wherein the at least one optical waveguide (40) has a core coated with stainless steel or plastic, wherein the core of the at least one optical waveguide (40) is in particular a glass core.

41. Measuring module (4) according to one of claims 30 to 40, wherein the measuring module (4) additionally has an electrical temperature sensor (70) and wherein the coupling device (8) is designed to transmit electrical signals provided by the electrical temperature sensor (70) from the measuring module (4) to the signal processing module (6) when the first coupling part (81) and the second coupling part (82) are coupled to one another, wherein the temperature sensor (70) is in particular an NTC sensor or a PTC sensor.

42. Measuring module (4) according to one of claims 30 to 41, wherein the at least one optical waveguide (40) is provided with a fluorescent dye which interacts with light radiated into the optical waveguide (40).

43. Measuring module (4) according to claim 42, wherein the at least one optical waveguide (40) has a light input surface (40b) coated with the fluorescent dye, which is formed on or in an end face at the distal end region (4a) of the measuring module (4), so that the fluorescent dye is in contact with the liquid (5) to be analyzed when the measuring module (4) is arranged in the liquid (5) to be analyzed.

44. Measuring module (4) according to one of claims 30 to 43, wherein the reference half-cell (60) has a reference chamber (62) filled with a reference electrolyte, with a reference electrode and a diaphragm (66), wherein the diaphragm (66) is designed such that it establishes an electrical contact between the reference electrolyte and the liquid (5) to be analyzed, wherein the measuring half-cell (50) extends in a longitudinal direction (L) in particular within the reference half-cell (60).

45. Measuring module (4) according to one of claims 30 to 44, wherein the first coupling part (81) has a plurality of electrical contacts (87) for transmitting the electrical signals between the measuring module (4) and the signal processing module (6) and an optical interface (85) for transmitting the light signals, wherein the electrical contacts (87) are arranged in particular around the optical interface (85).

46. ​​Signal processing module (6) for a combination sensor (2) for determining the pH value and oxygen content of a liquid (5) to be analyzed, in particular in a bioreactor (3), wherein the signal processing module (6) is designed to convert light signals transmitted by at least one optical fiber (40) into electrical signals in order to make it possible to determine the oxygen content of the liquid (5) to be analyzed from the light signals transmitted by the at least one optical fiber (40), and to process electrical signals provided at a measuring electrode (54) of a measuring chamber (52) filled with a measuring electrolyte in order to make it possible to determine the pH value of the liquid (5) to be analyzed from the electrical signals provided at the measuring electrode (54);wherein the signal processing module (6) has a second coupling part (81) that can be detachably coupled to a complementary first coupling part (81), wherein the second coupling part (82) is designed to receive light signals transmitted from the first coupling part (81) through at least one optical fiber (40) and electrical signals provided at a measuring chamber (52) filled with a measuring electrolyte when the first coupling part (81) and the second coupling part (82) are coupled to one another; wherein the complementary first coupling part (81) is in particular the coupling part (81) of a measuring module (4) according to one of claims 30 to 45.; 47. Signal processing module (6) according to claim 46, wherein a light source (41) is provided in the signal processing module (6) which is designed to emit light.

48. Signal processing module (6) according to claim 46 or 47, wherein a light detector (42) is provided in the signal processing module (6), which is designed to detect light that has been received via the second coupling part (82), wherein the coupling device (8) is designed in particular to transmit the light from the at least one optical waveguide (40) to the light detector (42).

49. Signal processing module (6) according to claim 48, wherein a light filter (43) is provided in front of the light detector (42), wherein the light filter (43) is transparent in particular for light with wavelengths in a range from 750 nm to 880 nm.

50. Signal processing module (6) according to one of claims 46 to 49, wherein the signal processing module (6) has at least one signal processing module optical waveguide (93) extending from the second coupling part (82) to the light source (41) and / or to the light detector (42).

51. Signal processing module (6) according to claim 50, wherein an optical fiber opening (84) is formed in an outer end face (82a) of the second coupling part (82), and wherein the signal processing module optical fiber (93) is inserted into the optical fiber opening (84) such that the signal processing module optical fiber (93) extends to the outer end face (82a) of the second coupling part (82).

52. Signal processing module (6) according to claim 50 or 51, wherein the signal processing module optical waveguide (93) is split outside the second coupling part (82) into a first optical waveguide strand (91) and a second optical waveguide strand (92), wherein the first optical waveguide strand (91) extends from the second coupling part (82) to the light source (41), and wherein the second optical waveguide strand (92) extends from the second coupling part (82) to the light detector (42).

53. Signal processing module (6) according to one of claims 46 to 52, wherein the signal processing module (6) extends in a longitudinal direction (L) and wherein the second coupling part (82) has a length of not more than 15 mm in the longitudinal direction (L), wherein the second coupling part (82) in the longitudinal direction (L) in particular has a length in the range of 8 mm to 12 mm.

54. Signal processing module (6) according to one of claims 46 to 53, wherein the second coupling part (82) has a plurality of electrical contacts (86) for transmitting the electrical signals between the measuring module (4) and the signal processing module (6) and an optical interface (84) for transmitting the light signals, wherein the electrical contacts (86) are arranged in particular around the optical interface (84).

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