Photochemical sensors and methods

Abstract

The present application relates to optochemical sensors and methods. The invention discloses an optochemical sensor for determining a measured variable related to measuring the concentration of an analyte in a fluid, comprising: a housing having at least one immersion area designed to be immersed in the measuring fluid; a removable cover with at least one sensor point, wherein the removable cover is removably arranged in the immersion area of the housing, and the sensor point is arranged on a circumferential surface; a radiation source arranged in the housing for radiating excitation radiation into the removable cover, wherein a deflection module is arranged in the removable cover and deflects the excitation radiation radiated onto the front side of the removable cover in the direction of the sensor point; a radiation receiver arranged in the housing for receiving the received radiation emitted by the sensor point; and a sensor circuit arranged in the housing and designed to control the radiation source, receive the signal of the radiation receiver and generate and output an output signal based on the signal of the radiation receiver.

Description

Field of the Invention

[0001] The present invention relates to a photochemical sensor and a method for using such a photochemical sensor to vary a measured variable associated with measuring the concentration of an analyte in a fluid. Background Art

[0002] Although the present invention will be described below with reference to an oxygen sensor, the inventive concept is not intended to be limited to sensors operating according to the principle of luminescence quenching. Instead, other process variables, in particular the concentration of certain analytes such as ions, molecules, gases or other chemical compounds, pH value or temperature, can also be measured by such an arrangement with conventional modifications. Companies of the Endress+Hauser Group offer and sell measuring devices suitable for determining the respective process variables in various variants.

[0003] The sensor includes, for example, a sensor head that contains an optical sensor element and is connected to a housing that contains a data processing unit, wherein the optical sensor element is irradiated with light by a light source. The light is reflected by the optical sensor element with specific optical properties, possibly after conversion, detected by a light receiver, and the signal of the light receiver representing the optical properties is evaluated by the data processing unit. The "optical sensor element" is also commonly referred to as a sensor spot or sensor membrane depending on its type.

[0004] EP2295953A1 discloses a device for measuring the concentration of a substance in a solution based on fluorescence measurement. The device includes a light source that emits transmitted light into the medium to be examined. An optical sensor element arranged in contact with the medium to be examined is excited by the transmitted light. In fluorescence measurement, the transmitted light is absorbed by the optical sensor element, and light of different wavelengths and intensities is reflected depending on the process variable, i.e., for example, the concentration of the analyte. The radiation reflected back by the optical sensor element is received by the light receiver as received light, converted into an electrical measured variable, and forwarded to the data processing unit. Depending on the properties of the optical sensor element and the transmitted light, the optical sensor reacts to different particle concentrations with different received light intensities, reception frequencies, phase angles, and / or attenuation curves.

[0005] A common sensor is, for example, the digital oxygen sensor "Memosens COS81D".

[0006] In principle, there are various methods for arranging the light source / light receiver opposite the sensor spot.

[0007] In the case of a sensor with sufficient energy supply, the light source / light receiver can be arranged directly on the optical sensor element. However, this is difficult to achieve with high-temperature sensors because it results in long and interference-prone connection lines from the data processing unit arranged far from the high-temperature measurement point to the optical components.

[0008] To avoid this, the light source and the light receiver can be placed away from the location of the hot medium to be inspected. Then the light can be guided to the optical sensor element via an optical waveguide.

[0009] Typically, exactly one sensor point is located in the general sensor. If another parameter is to be measured, another sensor must be used. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to provide a multi-parameter sensor that is easy to manufacture and handle.

[0011] This object is achieved by a photochemical substance, which includes: a housing, in particular a cylindrical housing, having at least one immersion area designed for immersion in a measurement fluid; a removable cover, in particular a cylindrical removable cover, having at least one sensor point, wherein the removable cover is removably arranged in the immersion area of the housing, and the sensor point is arranged on the circumferential surface; a radiation source arranged in the housing for radiating excitation radiation into the removable cover, wherein a deflection module is arranged in the removable cover and deflects the excitation radiation radiated onto the front side of the removable cover in the direction of the sensor point; a radiation receiver arranged in the housing for receiving the received radiation emitted by the sensor point; and a sensor circuit arranged in the housing and designed to control the radiation source, receive the signal of the radiation receiver, and generate and output an output signal based on the signal of the radiation receiver.

[0012] This results in a simple possibility of enabling multiple parameters with only a single sensor. The deflection module can direct the excitation radiation onto various areas of the circumferential surface, especially in the case of using multiple sensor points.

[0013] In one embodiment, it is provided that the deflection module deflects the excitation light at an angle of 90°, see also below.

[0014] This brings another advantage, which can also be seen when only a single sensor point is used. The fact that the point is no longer placed on the lower side as in the prior art but away from the lower side results in bubble-free analyte measurement. Since no bubbles remain laterally on the container wall and rise upwards, measurement is also possible in media with a tendency towards bubbles. The measurement window (i.e., the sensor point) is bubble-free. In the simplest case, this measurement is suitable for measuring a single measurement parameter (such as oxygen).

[0015] In one embodiment, it is provided that the deflection module includes a mirror, a prism, or a beveled glass rod. Generally, the deflection module is an optical component that can change the optical path.

[0016] In one embodiment, it is provided that the region of the circumferential surface on which the sensor points are arranged at least is fully hydrophobic, hydrophobic, superhydrophobic, hydrophilic or superhydrophilic.

[0017] In the assembled state, as required, the deflection module is always located in the removable cover. There are various possibilities in this regard.

[0018] In one embodiment, it is provided that the deflection module is arranged directly in the removable cover.

[0019] In one embodiment, it is provided that the deflection module is arranged in the front-side removable cover, for example in the base. In one embodiment, this is a mirror inclined at 45° to the vertical line of the cover.

[0020] In one embodiment, it is provided that the deflection module rotates by means of a threaded rotating base, and the light beam deflection surface thus changes the direction of the excitation radiation.

[0021] In one embodiment, it is provided that the deflection module is arranged in the adapter.

[0022] In one embodiment, it is provided that the adapter is designed as an inlay for the removable cover. Therefore, the adapter is an adapter for the removable cover.

[0023] In one embodiment, it is provided that the sensor includes an optical waveguide that conducts the excitation radiation from the radiation source in the direction of the removable cover, wherein the adapter is designed to be suitable for the optical waveguide. Therefore, in this embodiment, the adapter is an adapter for the optical waveguide.

[0024] In one embodiment, it is provided that the region of the circumferential surface with the sensor points is designed to be at least translucent or transparent for the excitation radiation and the received radiation.

[0025] In one embodiment, it is provided that the deflection module deflects the excitation radiation by 90°. In one embodiment, the deflection module is designed as a mirror or prism with a side surface inclined at 45° to the vertical line.

[0026] In one embodiment, it is provided that the removable cover is composed of gas ceramics, glass, borosilicate glass, quartz glass, sapphire, transparent or translucent plastics of the polycarbonate series, TOPAS, polysulfone, poly(n-methylmethacrylimide), ethylene norbornene copolymer or stainless steel and mixtures of these materials.

[0027] In one embodiment, it is provided that the removable cover includes at least two sensor points.

[0028] In one embodiment, it is provided that the sensor includes an orientation device assigned to at least one sensor point, wherein the orientation device is designed such that the sensor points can be clearly oriented on the sensor.

[0029] In one embodiment, it is provided that the orientation means comprises a tongue-and-groove connection. This enables a defined installation, such that the excitation radiation can be aligned at a defined angle.

[0030] In one embodiment, it is provided that the housing comprises a thread and the removable cover comprises a corresponding counter-thread.

[0031] In one embodiment, it is provided that the deflection module rotates from above, i.e., from the side facing away from the medium. In this case, the rotation occurs from the side of the sensor head. In this case, the stopper can be released, such that a rotational movement of the deflection module is possible, or the sensor can rotate freely in the cover container. The movement of the parts can also occur in an automated manner, for example, hydraulically driven by a fitting.

[0032] In one embodiment, it is provided that the deflection module can be activated by external excitation.

[0033] In one embodiment, it is provided that the deflection module can be activated by voltage, current, light entry, magnetic field, temperature, specific gas concentration, or a combination thereof.

[0034] As described above, the deflection module is located directly in the cover, either as an adapter in the cover or as an adapter of the light guide. The activatable deflection module conducts the excitation radiation by switching individual regions of the deflection module from transparent to reflective or from reflective to transparent on the side of the cover, such that different measurement parameters can be measured in a slightly time-shifted manner by switchable activation.

[0035] In one embodiment, it is provided that the deflection module is designed as a polyhedron or a cone.

[0036] In one embodiment, it is provided that the deflection module is composed of switchable layers that are radiation-impermeable or optically transparent depending on the switching position.

[0037] In one embodiment, it is provided that the deflection module is composed of switchable layers that are designed to be reflective or transparent for the excitation radiation depending on the switching position.

[0038] In one embodiment, it is provided that the sensor point comprises a carrier that is coated on the rear side and consists of a switchable film, wherein the switchable film is arranged, in particular welded, to a removable cover made of a plastic such as polycarbonate and passes or absorbs the excitation radiation.

[0039] In one embodiment, it is provided that the inner surface of the removable cover comprises a switchable layer and the reflective layer of the deflection module is switchable.

[0040] In one embodiment, it is provided that the front side of the removable cover is impermeable to the excitation radiation.

[0041] In one embodiment, it is thus provided that the lid comprises at least one switchable mirror layer and / or one switchable transparent layer.

[0042] In one embodiment, it is provided that the deflection module comprises a mirror which can be activated from reflection to transparency, or in which the deflection module consisting of a mirror polyhedron is stacked with a top surface which can be switched from reflection to transparency.

[0043] This object is also achieved by a method of changing a measured variable associated with measuring the concentration of an analyte in a fluid using a photochemical sensor as described above, the method comprising the steps of: removing a removable lid from a housing; rotating the removable lid; and reattaching the removable lid to the housing.

[0044] This object is also achieved by a method of changing a measured variable associated with measuring the concentration of an analyte in a fluid using a photochemical sensor as described above, the method comprising the step of: rotating the bottom of the removable lid.

[0045] This object is also achieved by a method of changing a measured variable associated with measuring the concentration of an analyte in a fluid using a photochemical sensor as described above, the method comprising the steps of: removing a removable lid from a housing; rotating an adapter in the removable lid; and reattaching the removable lid to the housing.

[0046] This object is also achieved by a method of changing a measured variable associated with measuring the concentration of an analyte in a fluid using a photochemical sensor as described above, the method comprising the steps of: removing a removable lid from a housing; rotating an adapter on an optical waveguide; and reattaching the removable lid to the housing.

[0047] This object is also achieved by a method of changing a measured variable associated with measuring the concentration of an analyte in a fluid using a photochemical sensor as described above, wherein the removable lid comprises a thread, the method comprising at least the steps of: rotating the removable lid or rotating the bottom of the removable lid. Description of the Drawings

[0048] This is explained in more detail with reference to the following drawings.

[0049] Figure 1 A schematic exploded view of the claimed photochemical sensor is shown.

[0050] Figure 2 The claimed photochemical sensor in one embodiment is shown.

[0051] Figure 3 The claimed photochemical sensor in one embodiment is shown.

[0052] Figure 4 Shows a claimed optochemical sensor in one embodiment.

[0053] Figure 5 Shows a claimed optochemical sensor in one embodiment.

[0054] Figure 6a -e shows a claimed optochemical sensor regarding the positioning of a removable cap.

[0055] Figure 7a / b shows a claimed optochemical sensor with an activatable deflection module in one embodiment.

[0056] Figure 8a -d shows a claimed optochemical sensor with an activatable deflection module in one embodiment.

[0057] Figure 9a -d shows various geometries of the activatable deflection module.

[0058] In the drawings, the same features are identified by the same reference numerals. Detailed Description

[0059] Figure 1 An optochemical sensor is schematically depicted. In the present exemplary embodiment, the sensor 1 is designed to determine the concentration of a gas (such as dissolved oxygen) dissolved in a measurement fluid. The sensor 1 has a housing 2 which, in the exemplary embodiment shown here, has a generally cylindrical design. The diameter is for example 12 mm or 40 mm. The housing 2 contains a sensor membrane 13 intended to be in contact with the measurement medium. The sensor membrane 13 includes in particular a luminescent dye embedded in a polymer matrix and whose luminescence is quenched by an analyte (such as oxygen here). Alternatively, the luminescent dye may also have the property that its luminescence is enhanced by the analyte. This is the case, for example, in the optical pH detection of luminophores based on the photoinduced electron transfer (PET) effect. The sensor membrane 13 may have a stable substrate and multiple layers applied to the substrate; see below. The sensor membrane 13 is also referred to as the sensor spot.

[0060] Arranged in the housing 2 is a radiation source 8 which can, for example, comprise one or more LEDs. Furthermore, arranged in the housing 2 is a radiation receiver 9 which can, for example, comprise one or more photodiodes. The radiation source 8 and the radiation receiver 9 are located in the receiving and transmitting unit 7. The housing 2 also contains an optical waveguide 17 which conducts the radiation emitted by the radiation source 8 to the sensor membrane 13 and conducts the luminescent radiation emitted by the luminescent dye embedded in the sensor membrane 13 to the radiation receiver 9. The optical waveguide 17 can comprise one or more optical fibers. For example, the optical waveguide 17 is formed by a fiber bundle which has a first arm connecting the radiation source 8 to the sensor membrane 13 and a second arm connecting the radiation receiver 9 to the sensor membrane 13. The optical sensor 1 has a sleeve-shaped housing section which is part of the sensor housing 2 and which is connected to the receiving and transmitting unit 7. The optical waveguide 17 is guided within the housing section. A possible embodiment of the optical waveguide 17 is realized as a glass rod. The glass rod is shaped accordingly, such as bent, drawn out, etc. Then, two separate arms are combined to form a single glass rod.

[0061] The radiation source 8 and the radiation receiver 9 are electrically connected to a sensor circuit. The sensor circuit is designed to excite and control the radiation source 8 to emit radiation. Furthermore, the sensor circuit is designed to receive and process the signal of the radiation receiver 9, which signal represents the luminescent radiation received by the radiation receiver 9. The processed signal serves as the measurement signal of the sensor 1 and can be output by the sensor circuit via the interface 10 to a superior unit, such as a measuring transmitter, a controller, a computer or an operating device. The interface 10 can be a cable connection fixedly connected to the sensor circuit, a detachable plug connection with current contacts, or a current-isolated, in particular inductively coupled, plug connection. Via a cable 19 connected to the interface 10, the sensor circuit can be supplied with energy and is also used to operate the radiation source 8. Furthermore, the sensor circuit can transmit signals (in particular data) to the superior unit via the cable 19 and optionally receive signals, in particular data, from the superior unit. The interface 10 is sold by the applicant under the name "Memosens".

[0062] The detection of the measured value and the evaluation of the signal of the radiation receiver 8 for determining the measured value can be divided between the sensor circuit and the superior unit. For example, the sensor circuit itself can be designed to control the radiation source 8. For this purpose, it can include a microcontroller that executes a computer program stored in the memory of the sensor circuit and used to control the radiation source 8 in order to detect the measured value. Alternatively, at least a part of the control function can also be executed by the superior unit, which then sends the corresponding control signal for actuating the radiation source 8 to the sensor circuit. Thus, in order to process the signal detected by the radiation receiver 8, the microcontroller can execute a computer program that is stored in the memory of the sensor circuit and used to evaluate the signal in order to determine the measured value. The correspondingly processed signal can be output to the superior unit via the interface 10 as a measurement signal representing the measured value.

[0063] The sleeve-shaped housing section is connected to the optical waveguide base 4 and the first thread 5, and the first thread is connected to the second thread 6 at the end of the housing section 2.

[0064] The removable cover 3 is assembled onto the optical waveguide base 4 or connected to the threads 20, 21. The removable cover 3 is generally cylindrical and has the sensor membrane 13 that has been mentioned for contacting the medium. The removable cover 3 has the housing 2 and a longitudinal axis located on the longitudinal axis A of the sensor 1.

[0065] The sensor membrane 13 has lumophore molecules embedded in the matrix material. When in contact with the measurement fluid containing a specific concentration of the analyte, the analyte penetrates into the polymer matrix and interacts with the luminescent dye. If the luminescent dye is excited by the radiation of the radiation source 8 to emit luminescent radiation, then, for example, in the case of oxygen detection in the polymer matrix, the luminescence is quenched according to the concentration of the analyte. However, conversely, an increase in fluorescence or phosphorescence is also possible (for example, in the case of optical pH measurement). The sensor circuit detects characteristic parameters such as the luminescence intensity, the phase shift of the luminescence signal, or the decay time of the luminescence by means of the radiation receiver 9, and determines the measured value of the concentration of the analyte present in the measurement medium by comparing with the calibration function.

[0066] The measurement principle of the optical sensor 1 is therefore based on the luminescence quenching principle, and is described in more detail below based on determining the concentration of dissolved oxygen in the measurement medium.

[0067] The concentration of oxygen molecules in the sensor film 13, and thus also the partial pressure of oxygen, corresponds in this case to the concentration or partial pressure in the measurement medium. During the measurement, a first light signal having at least one corresponding first wavelength is first emitted to excite the lumophore molecules via the radiation source 8. If the light signal impinges on the lumophore molecules, the latter are excited and emit a second light signal. If oxygen molecules are present in the sensor film 13, they attach themselves to the lumophore molecules and affect the emitted light signal (e.g., different intensity, different phase angle or different decay time). Thus, for example, energy is transferred through the collision of oxygen molecules with the luminescent dye. Thereby reducing the intensity and decay time of the emitted light signal. This effect is also called "quenching", and in this case, the oxygen molecules are called "quenchers". The intensity of the emitted light signal depends on the concentration of the quencher molecules. Of course, depending on which lumophore is used, in this way not only oxygen molecules but also other molecules can be determined. Particular mention should be made here of nitrogen oxides, sulfur oxides such as sulfur monoxide or sulfur dioxide and ozone.

[0068] The sensor film 13 can be applied to a substrate or carrier. The latter can be made of quartz, for example. The sensor film 13 can in particular have a layer containing a lumophore, a light protection layer, an adhesion layer or adhesion promoting layer and a top layer. In this case, the top layer is the layer in contact with the medium. However, alternatively or additionally, a proton conducting layer can also be provided. As described above, these layers can be arranged one on top of the other in a sandwich-like manner. However, it is also possible that the individual layers are covered by other layers or even completely encapsulated by others, including on the edge side.

[0069] As an alternative to the described luminescent sensor, the sensor point 13 comprises at least one layer which changes at least one property, such as changes color, when in contact with the process variable in the medium and absorbs the transmitted radiation according to the process variable.

[0070] Now first with reference to Figures 2 to 5 discuss the claimed sensor 1. Sensor 1 includes a deflection module 14. In various embodiments, the deflection module is implemented by a mirror or prism ( Figure 2 , 4 , 5) or a beveled glass rod ( Figure 3 ). The deflection module 14 is arranged in the removable cover 3 ( Figure 2 , 4 ), in the removable cover 3 with the adapter 15 ( Figure 5 ) or as an adapter 16 of the light guide 17 ( Figure 3 ) such that the light beam from the radiation source 8 impinges on the side of the removable cover at an angle of 90°.

[0071] The removable cover 3 has the external dimensions of a common removable cover of the prior art, but differs therefrom in that the lateral surface or a part of the lateral surface is transparent or translucent, while the bottom surface, which usually contains the sensor points 13, is light-impermeable. The circumferential surface 22 is the circumferential surface of the cylindrical removable cover. The circumferential surface 22 can be arbitrarily divided so that different sensor point surfaces can be irradiated and measured by the rotation of an adapter, a cover, a mirror, a prism or an optical waveguide. In this way, as a result of the conversion, at least two sensor parameters can be measured using the same sensor and the same removable cover. Of course, however, the measurement of a single sensor parameter is not excluded either. A measurement at a 90° angle to the optical waveguide 17 is also advantageous in the case of measuring parameters, because measurements can also be carried out in a measuring medium with bubbles since no lateral bubbles remain on the container wall.

[0072] The problems of this application will be briefly discussed again. It is not possible to directly bind the optical waveguide 17 to the tube wall because the losses would be too great, so that too little signal would ultimately reach the photodiode for a stable measurement. The fiber optic bundle allows measurements to be carried out without large energy losses. However, the fiber bundle cannot be arbitrarily bent in a very narrow space without breaking. Therefore, a 90° curvature of the optical waveguide fiber bundle on the lateral surface of the removable cover 3 is not considered.

[0073] Generally, many different geometries can be envisaged. For example, the sensor 1 and the removable cover 3 have an outer diameter of 12 mm. However, in principle, larger geometries, such as 40 mm, are also possible. The contour of the removable cover 3 is hygienic, flush-sealed by a stainless steel frame structure and does not allow gaps. The latter would falsify the measured values. The metal parts from the interior of the removable cover 3 are painted dark black as the metal ferrule of the optical waveguide 17 in order to avoid false measurements due to stray light.

[0074] In principle, suitable materials for the substrate of the removable cover 3 are all materials that are light-transmissive and stable with respect to temperature and humidity.

[0075] The term "temperature stable" should be understood here as: stable at 60 °C for 4 years; stable under high pressure at 121 °C for 30 minutes and at least 30 cycles; or stable under high pressure at 140 °C for 30 minutes and at least 30 cycles.

[0076] As described above, at least a part of the circumferential surface 22 of the sensor cover 3 must consist of a transparent or translucent material; the front side 12 consists of an opaque material or a transparent material with an internal coloring. Thus, a one-piece shape of the removable cover 3 is possible. For better cleanliness for hygiene requirements or for greater mechanical stability, an additional stainless-steel sleeve can surround the cover that is light-transmissive on the side. The material transition here terminates hygienically flush. Suitable materials for the substrate are glass ceramics, fused quartz, borosilicate glass, sapphire, disinfectable, preferably non-fluorescent plastics or hybrid materials (inorganic / organic) (e.g., polycarbonate, TOPAS, polysulfone, poly(n-methyl methacrylate), ethylene norbornene copolymer, polysulfone, poly(n-methyl methacrylimide).

[0077] The sensor point 13 is briefly discussed again. The sensitive layer consists of the flexible and actual sensor point 13. Suitable thin carriers are materials such as glass (Schott, Dow Corning), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), TOPAS, polycarbonate, ethylene norbornene copolymer, polysulfone, poly(n-butyl methacrylate), etc. However, activated or non-activated plastic films made of fluorinated polymers such as PVDF (polyvinylidene fluoride) or ETFE (tetrafluoroethylene) are also conceivable.

[0078] All materials insensitive to corrosion, such as stainless steel, Hastelloy, titanium, can be used as materials for the optional surrounding unit.

[0079] For applying the sensor point 13 to the removable cover 3, all techniques known to those skilled in the art, such as knife coating, spraying, dip coating, printing, spin coating, etc., are considered coating techniques.

[0080] A mixture of pigment and RTV silicone (such as E41) and a solvent is sprayed onto a polycarbonate film, for example, 50 μm thick, and then prepared with a carbon black-silicone mixture. The film is cured for several days, for example, at room temperature. In this case, a part of the film is covered with a mask. This step is repeated with three other pigments, for example. The choice of substrate can be different here, because a water-permeable material such as hydroxyethyl cellulose or polyurethane is used in the case of ion sensors. In the case of optical sensors (such as optical measurements of pH or CO 2 ), a reflective component is also partially added to amplify the intensity of the signal. Thus, a film with four separate strips is formed, and the four strips ideally terminate flush so that no foreign light enters. Possible crosstalk is avoided by precisely positioning the measurement beam.

[0081] To fix the sensor point 13 as a film, it is cut to a suitable size by laser, wrapped around a substrate and fixed by ultrasonic welding and combined with the substrate. Optionally, the transparent fusion site is coated. Alternatively, the film can also be fastened to the substrate by gluing, melting or shrinking with silicone. Similarly, at least one sensitive layer can be coated onto the film by spraying, scraping, spin-coating, printing, etc. Alternatively, the coated film is glued, inserted, ultrasonically welded, soldered or melted onto the transparent side of the lid in the container. Alternatively, it is inserted via a metal sleeve with a window.

[0082] In this way, a variety of even different materials can be connected to each other.

[0083] In the assembled state (lid on the sensor 1), the deflection module 14 is always located in the removable lid 3.

[0084] In Figure 2 and Figure 5 In the embodiment of, in the disassembled state, the deflection module 14 is also located in the removable lid 3.

[0085] In Figure 2 In, the deflection module 14 (such as the mentioned mirror or prism) is directly mounted in the lid. In this case, the deflection module 14 is rotated into the desired position on the front side 12 of the removable lid 3. The front side 12 can be rotated to the desired measurement position by rotation. With the aid of a positioning device 23, such as a tongue-and-groove connection, it can be rotated only in one direction by 90°. The measurement position is clearly indicated on the front side 12 of the removable lid 3. The removable lid 3 only needs to be screwed onto the sensor 1, for example by means of threads 20, 21, and the measurement can be carried out.

[0086] In Figure 4 In the embodiment shown, the lid 3 with the built-in deflection module 14 is placed in the defined position on the sensor 1 and positioned on the sensor 1 using a sleeve nut 24. The position information is indicated on the removable lid 3 and the sleeve nut 24. Optionally, the sleeve nut 24 and the removable lid 3 also include a positioning device.

[0087] Figure 5 An embodiment of an adapter 15 to the removable lid 3 is shown. The deflection module 14 is anchored to the adapter 15. Due to the defined slots, the adapter 15 can only be inserted into a specific installation position. Then the removable lid 3 is fastened to the sensor with the sleeve nut 24 so that the position can no longer change. Here, an ordinary sensor thread is also possible. The position for measuring the parameter is attached to the adapter 15 or the removable lid 3.

[0088] Figure 3An embodiment is shown. In this case, an adapter 16 for the light guide 17 is used. The adapter 16 with the deflection module 14 is, for example, a vitreous body with an inclination that is rotated onto the light guide 17. The adapter is mounted at a defined position on the light guide such that the analyte surface can be irradiated in a targeted manner. An inclined optical waveguide can be produced.

[0089] The substrate can be inserted and fastened in the stainless steel sleeve by pressing and screwing. However, other fastening techniques can also be considered, such as welding with glass paste or metal alloy, adhesive bonding, or shrink fitting.

[0090] The following possibilities of changing the beam direction by mounting the sensor 1 on the removable cover 3 and changing the position of the deflection module 14 are possible: rotation of the deflection module in the cover, rotation of the light guide adapter, rotation of the cover with the sleeve nut, and rotation of the adapter with the deflection module in the cover with the sleeve nut.

[0091] As described above, the removable cover 3 can be used to measure various parameters. For this purpose, the removable cover 3 can be modified such that the excitation radiation irradiates certain clearly defined regions inside the cover in a defined direction, in each case onto another sensor point 13. In this case, the position change is so distinct that no transition region can be irradiated. One possible way in this regard is the so-called snap rotation, where, in the case of four measurement parameters, the mirror can always only be rotated by a certain angle, for example 90°. In this case, the rotation can only be carried out in one direction and with a certain rotation angle clearly. Intermediate angles are not possible. In this regard, see Figure 6a -e.

[0092] The preferred measurement positions can be identified by fixed markings on the removable cover 3 or the deflection module 14. Thus, the unintentional measurement of incorrect parameters can be prevented. In some measurements, different analytes may be measured at the same modulation frequency, and the incorrect measurement may not be noticed immediately. Ideally, the same excitation LED, the same photodiode, and the same filter can be used to measure different parameters (e.g., oxygen and optical pH). However, the modulation frequency can also be changed. As long as the emitted light passes through the filter for the photodiode and can be detected, variable LEDs with different excitation wavelengths can be installed.

[0093] Figures 7a - 9dAn embodiment is shown. In this case, the deflection module 14 can be activated. This is done by external excitation. Possible external excitations are carried out by applying voltage, light, gas, temperature, current or by means of magnetic excitation or a combination thereof. This results in a change in the position of the deflection module, as a result of which the excitation radiation is deflected by 90°. Suitable materials are applied to the geometry coated with the next layer. These can also be multilayer systems.

[0094] In the case of an electrochromic layer, the switching is carried out by means of a current with a currentless final state in the form of darkening (blue coloring).

[0095] In the case of a photochromic layer, the switching is carried out in the form of darkening by irradiation.

[0096] In a photoelectrochromic layer, the switching is carried out by electrochromic switching activated by solar radiation.

[0097] In the case of a thermochromic layer or a thermochromic layer, when the threshold temperature is exceeded, the switching is carried out in the form of a color change or white clouding.

[0098] In a polymer-dispersed liquid crystal system, the switching is carried out in a clear form by orienting the light-scattering liquid crystals after applying a voltage.

[0099] In the case of a suspended particle device, the switching is carried out in a clear form by orienting the optically anisotropic absorbing particles after applying a voltage.

[0100] The switching can also be carried out by means of a switchable metal hydride-based mirror, by means of a gasochromic layer or by means of one or more optically switchable transistors.

[0101] Figure 7a / b shows the different switching states of the sensor 1 and the switchable mirror. In Figure 7a , the right side is mirror-activated; in Figure 7b , the left side is mirror-activated. In Figure 7a / b, the deflection module 14, here in the form of a pyramid, is switched by means of a voltage source 25. The transparent face 26 and the reflective face 27 are each marked or hatched.

[0102] Figure 8a -d shows an embodiment for switching the deflection module 14 with a switchable transparent or non-transparent face in the removable cover 3. In each case, only the section with the light guide 17 is shown, which transmits or receives the transmitted or received radiation.

[0103] In Figure 8aIn [the device], the mirror consists of superposed switchable substances which, depending on the switching position, are at least for certain light impermeable, but absorptive and optically transparent, or in which, depending on the switching, the optical layer is reflective (reference numeral 27) and transparent (reference numeral 26).

[0104] In Figure 8b and Figure 8c [the device], the inner face of the removable cover 3 is provided with a switchable layer. The reflective layer is likewise switchable ( Figure 8b ) or non-switchable ( Figure 8c ).

[0105] In Figure 8d [the device], the sensor point 13 is a carrier which is coated on the rear side and consists of a switchable film 30 and is, for example, welded to a plastic cover made of polycarbonate and can let light pass through it or absorb it. This embodiment includes a non-transparent dot surface 28 and a transparent inner face 29 of the removable cover 3.

[0106] As previously described, the sensor 1 is used for multi-parameter measurement. For this purpose, the sensor cover can be modified such that the sensor beam irradiates certain clearly defined regions inside the cover in a defined direction. In this case, the position change is so distinct that no transition region can be irradiated. One possibility here is a distinct polyhedral structure in which the light beam always occurs only around a specific exposed reflective surface and, by switching the exposed surface, the irradiated surface can be rotated, for example, by 90° in the case of four measurement parameters (for example, in a pyramid structure). In this case, the free reflective surface can be uncovered and can irradiate the sensitive layer 13 clearly in only one direction and at a certain angle of rotation. This is predetermined by the geometry of the beam body and its mounting position. Intermediate angles are not possible.

[0107] Figure 9a -d shows a polyhedral structure or a broader structure, such as a triangular prism ( Figure 9a ), a cone ( Figure 9b ), a pyramid ( Figure 9c ) or a "gable-fronted roof" ( Figure 9d ) or a "gable roof".

[0108] Here, the upper top surface is in each case covered with a switchable mirror layer (transition: transparent reflective) or an electrochromic layer (transition non-light-transmissive - transparent), see above. The angle of the face of the reflective surface or the exposed reflective surface (when it is directly attached to the surface) is arranged at an angle of 45° to the bottom surface of the sensor cover or to the vertical line of the optical waveguide.

[0109] In each case, a different number of switchable faces is possible: three in the case of a triangular prism, n in the case of a cone, four in the case of a pyramid, four in the case of a "gable front peak", and two in the case of a "gable roof". An optical measurement of a physical or chemical measured variable can be carried out on each face. The reflecting face can be triangular, trapezoidal or rectangular. In the case of a cone with a circular face, the positioning cannot be predetermined via the geometric faces of the reflector, but only via the defined exposure or activation of the reflecting face. Thus, the size of the reflecting face, for example the opening gap, is determined by the pixelation or grating of the light diffracting face and / or the corresponding reflecting or covering layer on the substrate on which the sensitive layer is applied.

[0110] With a symmetrical structure, a preferred mounting position of the reflection unit is not necessary, since the correct position is automatically obtained during normal lid assembly. However, in other embodiments, a preferred orientation is provided, which is achieved by means of the orientation device 23, see above, since incorrect assembly will result in incorrect measured values.

[0111] The preferred measurement position can be identified by a fixed mark on the removable lid 3 or the adapter. Thus, an unintentional measurement of incorrect parameters can be prevented. In some measurements, different analytes may be measured at the same modulation frequency, and an incorrect measurement may not be noticed immediately. Ideally, the same excitation LED, the same photodiode and the same filter can be used to measure different parameters (e.g., oxygen and optical pH). However, the modulation frequency can also be changed. As long as the emitted light passes through the filter for the photodiode and can be detected, variable LEDs with different excitation wavelengths can be installed.

[0112] List of reference numerals

[0113] 1 Photochemical sensor

[0114] 2 Housing

[0115] 3 Removable lid

[0116] 4 Optical waveguide base

[0117] 5 Thread

[0118] 6 Thread

[0119] 7 Receiving and transmitting unit

[0120] 8 Radiation source

[0121] 9 Radiation receiver

[0122] 10 Coupling point

[0123] 11 Optical waveguide

[0124] The front side of 12 3

[0125] 13 Sensor film / Sensor point

[0126] 14 Deflection module

[0127] 15 Adapter to 3

[0128] 16 Adapter to 17

[0129] 17 Light guide

[0130] 19 Cable

[0131] 20 Thread

[0132] 21 Thread

[0133] 22 The circumferential surface of 3

[0134] 23 Orientation device

[0135] 24 Sleeve nut

[0136] 25 Power supply

[0137] 26 Transparent surface

[0138] 27 Reflective surface

[0139] 28 Non-transparent dot surface

[0140] 29 The transparent inner surface of 3

[0141] 30 Sensor point with a switchable rear side

[0142] A The longitudinal axis of the sensor

Claims

1. A photochemical sensor (1) for determining a measured variable related to the concentration of an analyte in a measurement fluid, comprising: - a housing (2), which is a cylindrical housing having at least one immersion area designed to be immersed in the measurement fluid; - a removable lid (3), which is a cylindrical removable lid carrying at least two sensor points (13), wherein the removable lid (3) is removably arranged in the immersion area of the housing (2), wherein the at least two sensor points (13) are arranged on the circumferential surface of the removable lid (3); - a radiation source (8) arranged in the housing (2) for radiating excitation radiation into the removable lid (3), wherein a deflection module (14) is arranged in the removable lid (3) and deflects the excitation radiation radiated into the removable lid (3) at the front side thereof in the direction of the sensor points (13); - a radiation receiver (9) arranged in the housing (2) for receiving the received excitation radiation emitted by the sensor points (13); and - a sensor circuit arranged in the housing (2) and designed to control the radiation source (8), receive the signal of the radiation receiver (9) and generate and output a signal based on the signal of the radiation receiver (9); wherein the deflection module (14) comprises a mirror, a prism or a beveled glass rod.

2. The photochemical sensor (1) according to claim 1, wherein the deflection module (14) is arranged in an adapter.

3. The photochemical sensor (1) according to claim 2, wherein the photochemical sensor (1) comprises an optical waveguide (17) that conducts excitation radiation from the radiation source (8) in the direction of the removable lid (3), wherein the adapter is designed to fit the optical waveguide (17).

4. The photochemical sensor (1) according to any one of claims 1 - 3, wherein the area of the circumferential surface with the sensor points (13) is designed to be at least semi-transparent or transparent for the excitation radiation and the received radiation.

5. The photochemical sensor (1) according to any one of claims 1 - 3, wherein the deflection module (14) deflects the excitation radiation by 90°.

6. The photochemical sensor (1) according to any one of claims 1 - 3, wherein the removable lid (3) is made of gas ceramic, glass, sapphire, a transparent or semi-transparent plastic of the polycarbonate series, TOPAS, polysulfone, poly(n-methylmethacrylimide) or an ethylene norbornene copolymer, or a mixture of stainless steel and gas ceramic, glass, sapphire, a transparent or semi-transparent plastic of the polycarbonate series, TOPAS, polysulfone, poly(n-methylmethacrylimide) and an ethylene norbornene copolymer.

7. The optochemical sensor (1) according to claim 6, wherein, the glass includes borosilicate glass and fused quartz.

8. The optochemical sensor (1) according to any one of claims 1 - 3, wherein, the optochemical sensor (1) includes an orienting device (23) assigned to at least one sensor point, wherein the orienting device (23) is designed to enable the sensor point (13) to be clearly oriented on the optochemical sensor (1).

9. The optochemical sensor (1) according to claim 8, wherein, the orienting device (23) includes a tongue - and - groove connection.

10. The optochemical sensor (1) according to any one of claims 1 - 3, wherein, the housing (2) includes a thread (20), and the removable cap (3) includes a corresponding reverse thread.

11. The optochemical sensor (1) according to any one of claims 1 - 3, wherein, the deflection module (14) can be activated by external excitation.

12. The optochemical sensor (1) according to claim 11, wherein, the deflection module (14) can be activated by voltage, current, light, magnetic field, temperature, gas, or a combination thereof.

13. The optochemical sensor (1) according to any one of claims 1 - 3, wherein, the deflection module (14) is designed as a polyhedron or a cone.

14. The optochemical sensor (1) according to any one of claims 1 - 3, wherein, the deflection module (14) includes a mirror that can be activated to be transparent from reflection, or wherein the deflection module composed of a mirror - faced polyhedron is stacked with a top surface that can be switched from reflection to transparency.

15. A method for using the optochemical sensor (1) according to any one of claims 1 - 14 to change a measured variable related to the concentration of an analyte in a measurement fluid, comprising the following steps: - removing the removable cap (3) from the housing (2), - rotating the removable cap (3), and - re - attaching the removable cap (3) to the housing (2).

16. A method for using the optochemical sensor (1) according to any one of claims 1 - 14 to change a measured variable related to the concentration of an analyte in a measurement fluid, wherein, the removable cap (3) includes a reverse thread, and the method at least includes the following steps: - rotating the removable cap (3) or rotating the bottom of the removable cap (3).

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