Optical sensor element, optical ph sensor and method for monitoring the function of an optical ph sensor

Abstract

The present invention relates to an optical sensor element, an optical pH sensor and a method for monitoring the function of an optical pH sensor. The optical chemical sensor element comprises: - a substrate layer having a first substrate side facing a measurement medium and a second substrate side opposite the first substrate side; - a functional layer arranged on the first substrate side and having a first reference dye, an indicator dye and a second reference dye different from the first reference dye, wherein the first reference dye comprises an inorganic material and is not sensitive to pH and is adapted to emit a first luminescence signal upon stimulation with a first stimulation signal; the indicator dye comprises an organic material and is sensitive to pH and is adapted to emit a third luminescence signal upon stimulation with the first stimulation signal; the second reference dye comprises an organic material and is not sensitive to pH and has a passivation functional group and is adapted to emit a second luminescence signal upon stimulation with the first stimulation signal; the substrate layer is transparent to the stimulation signal and the luminescence signals.

Description

Technical Field

[0001] This invention relates to an optical sensor element, an optical pH sensor, and a method for monitoring the function of the optical pH sensor. Background Technology

[0002] In industrial applications such as environmental analysis in food technology, biotechnology, and pharmaceuticals, especially in water management and for highly variable laboratory applications, the concentration of measured variables such as pH, conductivity, or even analytes such as ions or dissolved gases in the gaseous or liquid measurement medium is crucial. These measured variables can be obtained and / or monitored, for example, using electrochemical sensors such as optical, potential, current, voltammetric, or coulometric sensors, or even conductivity sensors.

[0003] Optical pH sensors are based on photochemical reactions with the measurement medium. Typically, these sensors contain a luminescent material that emits light when stimulated by a light source. This luminescent material is also pH-sensitive, meaning the light emitted is influenced by the pH value of the measurement medium.

[0004] Known problems with previous optical pH sensors include high ionic strength dependence, high temperature dependence, and low drift stability. Ionic strength and temperature dependence are caused by the measurement medium, and can therefore be controlled if the pH sensor is used only in specific applications, such as below 80°C. Drift of the pH sensor leads to distortion of the measurement results. Currently used pH sensors often have unstable fluorophores or fluorescein derivatives that begin to drift after a short time. This is due to the photobleaching and leaching of the indicator dye. The photobleaching of the indicator dye occurs due to oxidation; the leaching occurs due to washing out the indicator dye. Over time, increasingly stable fluorophores have been discovered in university research, which leach less due to fewer polar groups. Nevertheless, the drift stability problem caused by photobleaching remains. Summary of the Invention

[0005] Therefore, the object of the present invention is to realize an optical pH measurement that can be reliably and simply implemented.

[0006] According to the present invention, this objective is achieved by a photochemical sensor element for a photochemical pH sensor according to claim 1.

[0007] The photochemical sensor element according to the present invention comprises: - A substrate layer having a first substrate side facing the measuring medium and a second substrate side opposite to the first substrate side; - A functional layer disposed on the first substrate side and having a first reference dye, an indicator dye, and a second reference dye different from the first reference dye. The first reference dye comprises an inorganic material and is pH insensitive, and is adapted to emit a first luminescent signal upon stimulation with a first stimulus signal. The indicator dye comprises an organic material and is pH sensitive, and is adapted to emit a third luminescent signal upon stimulation with the first stimulus signal. The second reference dye comprises an organic material and is pH insensitive, has a passivated functional group, and is adapted to emit a second luminescent signal when stimulated with the first stimulus signal. The substrate layer is transparent to both the stimulation signal and the emission signal.

[0008] Using the photochemical sensor element according to the invention, the drift of the sensor can be identified and quantified to compensate for the measured value determined by the sensor relative to the determined drift. Because the photochemical sensor element has two different reference dyes, and one of the reference dyes contains the same drift characteristics as the indicator dye, the drift of the indicator dye can be indirectly determined by identifying the drift of the reference dye. For this purpose, it is only necessary to compare the two reference dyes with each other. With the help of the photochemical sensor element according to the invention, the drift of the photochemical pH sensor can be checked during continuous operation and the current measured value can be compensated based on the determined drift. Therefore, it is not necessary to remove the photochemical pH sensor from the measurement point to determine the pH sensor drift in a medium with a known pH value. This minimizes the workload of operating the pH sensor and maximizes the quality of the measurement results.

[0009] According to one embodiment of the present invention, the functional layer is subdivided into at least two functional segments. The first functional section includes the first reference dye, the indicator dye, and the second reference dye. The second functional section contains the first reference dye and the indicator dye. Or the first reference dye and the second reference dye, Or the indicator dye and the second reference dye.

[0010] According to one embodiment of the present invention, a comparison layer having a first comparison section is disposed on the second substrate side of the substrate, wherein the first comparison section has the first reference dye, the second reference dye, or the indicator dye.

[0011] According to one embodiment of the present invention, the comparison layer has a plurality of comparison segments, wherein each comparison segment has the first reference dye, the second reference dye, or the indicator dye.

[0012] According to one embodiment of the present invention, the functional layer is subdivided into at least three functional segments, wherein the first functional segment has the first reference dye, the second functional segment has the indicator dye, and the third functional segment has a second reference dye that is different from the first reference dye and has passivation functional groups.

[0013] According to one embodiment of the present invention, the functional layer has more than three functional segments and each functional segment has a different dye or a different combination of dyes.

[0014] According to one embodiment of the present invention, the functional layer is circular and the functional segment is formed by radial subdivisions of the functional layer, or the functional layer is rectangular and the segment is formed by rectangular subdivisions of the functional layer.

[0015] According to one embodiment of the present invention, the functional layer has a proton-conducting matrix, and the first reference dye and / or the organic indicator dye and / or the second reference dye are uniformly arranged in the proton-conducting matrix.

[0016] According to one embodiment of the present invention, the photochemical sensor element further comprises a selection layer disposed on the side of the functional layer opposite to the substrate layer and is permeable to protons.

[0017] According to one embodiment of the invention, each of the functional segments contacts the substrate layer or another layer with a first side surface and contacts the selection layer or another layer or measurement medium with a second side surface opposite to the first side surface.

[0018] According to one embodiment of the invention, the first reference dye has a material selected from the following: titanate, nitride, gallate, sulfide, sulfate, aluminate, silicate, preferably Han blue, Han violet, Egyptian blue, ruby ​​red, aluminum borate, chromated yttrium aluminum borate, gadolinium aluminum borate, manganese (IV) (doped) activated magnesium titanate, manganese (IV) activated magnesium fluorogermanate, ruby, emerald green and / or europium (III) activated yttrium oxide.

[0019] According to one embodiment of the invention, the indicator dye comprises a material or mixture selected from the following: BODIPY, aza-BODIPY, porphyrine, phthalocyanine, hindered coumarin, perylene diimide, anthocyanin, diketopyrrolopyrrole (DPP), quinacridone (QD), 7-[2-(decyloxycarbonyl)-phenyl]-10-diethylamino-3-hydroxy-benzo[c]xanthanium Perchlorate (XP), azidiotrigonene (azadioxatriangulenium, ADOTA), diazaoxatrian gulenium (DAOTA), pyranine (HPTS), 6,8-dihydroxypyrene-1,3-disulfonic acid (DHPDS), fluorescein and its derivatives.

[0020] According to one embodiment of the invention, the second reference dye has the indicator dye that has been reacted by esterification, etherification or amidation.

[0021] According to one embodiment of the present invention, the photochemical sensor element has at least one additional layer disposed on the substrate layer and / or the functional layer and / or the selection layer, wherein the additional layer is, for example, a protective layer, a darkening layer, a support layer or a barrier layer.

[0022] The objectives of the invention are further achieved by using a photochemical pH sensor according to one embodiment of the invention.

[0023] The photochemical sensor according to the present invention comprises: - Sensor body, which includes a light source, a photodetector, and a control unit. The control unit is connected to the light source and the photodetector, and is adapted to control the light source and evaluate the signal detected by the photodetector; - A sensor head having a photochemical sensor element according to the invention; The sensor body and the sensor head are arranged such that the light source is adapted to emit at least one stimulus signal in a manner that irradiates the photochemical sensor element. The photodetector is adapted to detect the light emission signal emitted by the photochemical sensor element.

[0024] According to one embodiment of the present invention, the photodetector has a filter unit adapted to filter a first luminescent signal emitted by the first reference dye, a second luminescent signal emitted by the second reference dye, and a third luminescent signal emitted by the indicator dye.

[0025] According to one embodiment of the invention, the photochemical pH sensor further comprises an optical waveguide including at least two conductive fibers, and the light source is adapted to generate at least two independent stimulation signals. The first conductor fiber is arranged such that the first stimulation signal is directed to the first functional segment. Furthermore, the second conductor fiber is arranged such that the second stimulation signal is directed to the second functional segment.

[0026] According to one embodiment of the present invention, the optical waveguide has a fourth conductor fiber and a comparison section disposed at one end of the fourth conductor fiber.

[0027] The objective of the invention is further achieved by a method for monitoring the function of a photochemical pH sensor according to one embodiment of the invention.

[0028] The method according to the present invention includes at least the following steps: - Provides a photochemical pH sensor according to the present invention, - The control unit controls the light source so that a first stimulus signal is emitted onto the photochemical sensor element to stimulate the first reference dye, the second reference dye, and the indicator dye. - The first emission signal, the second emission signal, and the third emission signal are detected using the aforementioned photodetector. - The control unit compares the first luminescent signal emitted by the first reference dye with the second luminescent signal emitted by the second reference dye. - Determine the reference signal difference or reference signal ratio between the first emitted signal and the second emitted signal. - Determine the measurement signal difference or measurement signal ratio between the first emission signal and the third emission signal. - The pH value of the measurement medium is determined based on the determined difference between the measured signal and the reference signal, or based on the ratio of the measured signal and the ratio of the reference signal.

[0029] According to one embodiment of the present invention, if the measurement signal difference, the reference signal difference, the measurement signal ratio, or the reference signal ratio exceeds or falls below a predetermined limit value, the control unit outputs a warning message.

[0030] According to one embodiment of the invention, the photochemical pH sensor further comprises an optical waveguide having at least two conductive fibers, and the light source is adapted to generate at least two independent stimulation signals. The first conductor fiber is arranged such that the first stimulation signal is directed to the first functional segment. Furthermore, the second conductor fiber is arranged such that the second stimulation signal is directed to the second functional segment. The step of controlling the light source using the control unit is performed in such a way that a first stimulation signal is emitted onto a first functional segment using the first conductor fiber, and a second stimulation signal is emitted onto a second functional segment using the second conductor fiber in a time-delayed manner or simultaneously with the first stimulation signal. Attached Figure Description

[0031] The invention will be explained in more detail below with reference to the accompanying drawings. The drawings are shown below: - Figure 1 : A schematic diagram of the photochemical sensor element according to the present invention; - Figure 2 : Figure 1 A schematic diagram of an alternative embodiment of the photochemical sensor element shown; - Figure 3 : Figure 1 A schematic diagram of another alternative embodiment of the photochemical sensor element shown; - Figure 4 : A schematic diagram of the photochemical pH sensor according to the present invention; - Figure 5 : Figure 4 A schematic diagram of an alternative embodiment of the photochemical pH sensor shown; - Figure 6 : Figure 4 A schematic diagram of another alternative embodiment of the photochemical pH sensor shown.

[0032] - Figure 7 : Figure 4 A schematic diagram of another alternative embodiment of the photochemical pH sensor shown. Detailed Implementation

[0033] Figure 1 An exemplary embodiment of a photochemical sensor element 10 for use in a photochemical pH sensor 1 is shown. The photochemical sensor element 10 is intended for use in the photochemical pH sensor 1 to determine the pH value of a measurement medium in contact with the photochemical pH sensor 1.

[0034] The photochemical sensor element 10 includes a substrate layer 20 having a first substrate side 21 and a second substrate side 22. The first substrate side 21 is the side of the substrate layer 20 facing the measurement medium. A functional layer 30 is disposed on the first substrate side 21 (see...). Figures 1-7The functional layer 30 faces the measurement medium and is configured to contact, at least ionically, the measurement medium. Depending on the embodiment, a comparison layer 60 having at least one first comparison segment 61 may be disposed on the second substrate side 22 (see [link]). Figures 3-5 (Implementation method). The comparison layer 60 is not oriented towards the measurement medium and is designed not to contact the measurement medium.

[0035] The functional layer 30 has a first reference dye RF1, an indicator dye IF, and a second reference dye RF2 that is different from the first reference dye RF1. For example... Figure 1 As shown, the functional layer 30 can be designed as a single unit. For example... Figures 2-7 As shown, the functional layer 30 can also be alternatively designed as a multi-piece design.

[0036] If luminescence or luminescent signal is mentioned below, it means fluorescence or a fluorescent signal and / or phosphorescence or a phosphorescent signal. Organic dyes typically exhibit fluorescence and inorganic dyes typically exhibit phosphorescence.

[0037] The first reference dye RF1 comprises an inorganic phosphorescent material and is adapted to emit a first emission signal L1 upon stimulation with a first stimulus signal S1. The first stimulus signal S1 preferably has a wavelength range of 400 nm to 600 nm or 500 nm to 600 nm. The first emission signal L1 preferably has a wavelength range of 600 nm to 1100 nm.

[0038] The luminescent indicator dye IF comprises an organic material and is pH sensitive, and is adapted to emit a second luminescent signal L2 upon stimulation with the first stimulus signal S1. The second luminescent signal L2 is preferably in the wavelength range of 400 nm to 1100 nm. Preferably, the wavelength range of the second luminescent signal L2 is 600 nm to 1100 nm. Here, "pH sensitive" means that the second luminescent signal L2 depends on the pH value of the measurement medium, such that the intensity and / or decay time of the second luminescent signal L2 depends on the pH value of the measurement medium.

[0039] The second luminescent reference dye RF2 comprises an organic material and has passivated functional groups. The passivated functional groups in the second organic reference dye RF2 exist as active functional groups in the indicator dye IF. In principle, the only difference between the second organic reference dye RF2 and the indicator dye IF is the passivated group. The active functional groups impart pH sensitivity to the indicator dye IF.

[0040] The second organic reference dye RF2 is adapted to emit a third luminescent signal L3 when stimulated by the first stimulus signal S1. The third luminescent signal L3 has a wavelength range of 400 nm to 1100 nm. Preferably, the third luminescent signal L3 has a wavelength range of 600 nm to 1100 nm.

[0041] The substrate layer 20 is preferably transparent to the stimulation signal S1 and the light emission signals L1, L2, L3.

[0042] Figure 2 An embodiment of the photochemical sensor element 10 having a multi-piece functional layer 30 is shown. The functional layer 30 is in... Figure 2 The functional layer 30 is further divided into two functional sections 31 and 32. Of course, the functional layer 30 can also be divided into more than two functional sections.

[0043] exist Figure 2 In the illustrated embodiment, the first functional section 31 includes the first reference dye RF1, the indicator dye IF, and the second reference dye RF2. The second functional section 32 includes the first reference dye RF1 and the indicator dye IF.

[0044] In an alternative embodiment (not shown), the second functional segment 32 has the second reference dye RF2 and the indicator dye IF, or the first reference dye RF1 and the second reference dye RF2.

[0045] The second functional segment 32 allows for the application of a so-called ratiometry method, which will be discussed in detail later. Similarly, the second functional segment 32 allows predetermined regions of the photochemical sensor element 10, namely the first functional segment 31 and the second functional segment 32, to be stimulated with different stimulation signals S1, S2 emitted at different times, for example, with different wavelengths and / or at different wavelengths. Likewise, the separate arrangement of the segments allows for the separate detection of the luminescence signal of the dye arranged in the segments. The photochemical pH sensor 1 will be discussed in more detail later.

[0046] Figure 3 An embodiment is shown in which the functional layer 30 is subdivided into two functional segments 31 and 32. Each of the two functional segments 31 and 32 has a different dye. The first functional segment 31 has the second reference dye RF2; the second functional segment 32 has the indicator dye IF. Furthermore, a comparison layer having a first comparison segment 61 is mounted on the second substrate side. The first comparison segment 61 has the indicator dye IF.

[0047] By dividing the dyes RF2 and IF into separate segments 31, 32, and 61, the dyes RF2 and IF can be stimulated with different stimulation signals S1, S2, and S3 or the same stimulation signal, or the luminescent signals L3', L2, and L3 emitted by the dyes RF2 and IF can be detected respectively.

[0048] Of course, the functional layer 30 can be subdivided into more than three functional segments to, for example, arrange dye combinations of the first reference dye RF1 and / or the second reference dye RF2 and / or the indicator dye IF for ratio measurement in other functional segments.

[0049] The functional layer 30 of the photochemical sensor element 10 is, for example, circular. If the circular functional layer 30 has functional segments 31, 32, 33, they are formed through radial sub-sections of the functional layer 30.

[0050] The functional layer 30 of the photochemical sensor element 10 can also be rectangular. In this case, the functional segments 31, 32, 33, and 34 are formed by rectangular sub-sections of the functional layer 30. It should be understood that other shapes of the functional layer 30 and the functional segments are also possible.

[0051] In an embodiment compatible with the above embodiments, the functional layer 30 has a proton-conducting matrix. In this case, the first inorganic reference dye RF1 and / or the organic indicator dye IF and / or the second organic reference dye RF2 are uniformly arranged in the proton-conducting matrix.

[0052] By utilizing the uniform arrangement of dyes RF1, RF2, and IF in the proton conduction matrix, crosstalk / energy transfer between excited and unexcited dyes is prevented.

[0053] By introducing a material with a large surface area and covalent bonding onto the surface of the proton-conducting matrix, an optimal drift-stabilized film with the lowest possible load is produced.

[0054] In embodiments compatible with the above embodiments, the photochemical sensor element 10 further includes a selection layer 40 (see...). Figure 7 The selector layer 40 is disposed on the side of the functional layer 30 opposite to the substrate layer 20. The selector layer 40 is adapted to filter specific analytes from the measurement medium. The selector layer 40 is permeable to protons. The selector layer 40 can also serve as a protective layer for the functional layer 30.

[0055] In an embodiment compatible with the above embodiments, the photochemical sensor element 10 has at least one additional layer. This additional layer is disposed on the substrate layer 20 and / or the functional layer 30 and / or the selection layer 40 (not shown). The additional layer is, for example, a protective layer, a darkening layer, a support layer, or a barrier layer.

[0056] In embodiments compatible with the above embodiments, the first reference dye RF1 has a material selected from the following: titanate, nitride, gallate, sulfide, sulfate, aluminate, silicate, preferably Han blue, Han violet, Egyptian blue, ruby ​​red, aluminum borate, chromium yttrium aluminum borate, gadolinium aluminum borate, manganese (IV)-(doped) activated magnesium titanate, manganese (IV)-activated magnesium fluorogermanate, ruby, emerald green and / or europium (III)-activated yttrium oxide.

[0057] In embodiments compatible with the above embodiments, the indicator dye IF has a material or mixture selected from the following: BODIPY (dipyrrole methylene boron difluoride), aza-BODIPY, porphyrin, phthalocyanine, hindered coumarin, perylene diimide, anthocyanin, diketopyrrolopyrrole (DPP), quinacridone (QD), 7-[2-(decyloxycarbonyl)-phenyl]-10-diethylamino-3-hydroxy-benzo[c]xanthanium Perchlorate (XP), azidiotrigonene (ADOTA), diazaoxatrigonene (DAOTA), hydroxypyrene sulfonic acid (HPTS), 6,8-dihydroxypyrene-1,3-disulfonic acid (DHPDS), fluorescein and its derivatives.

[0058] Examples of aza-BODIPY indicator dyes:

[0059] Examples of aza-BODIPY indicator dyes:

[0060] As DAOTA azidiotrigonene Examples of indicator dyes:

[0061] An example of the second reference dye RF2:

[0062] An example of the second reference dye RF2:

[0063] An example of the second reference dye RF2:

[0064] In an embodiment compatible with the above embodiments, the second reference dye RF2 has the indicator dye IF reacted by esterification, etherification or amidation.

[0065] Figures 5-7 An exemplary embodiment of the photochemical pH sensor 1 according to the present invention is shown.

[0066] In another embodiment, the functional layer 30 of the photochemical sensor element 10 is subdivided into the following seven functional segments (not shown): The first functional section includes: - Indicator dyes with polyurethane properties; - A second reference dye RF2 with a polyurethane BODIPY and a decay time in the nanosecond range; and - The first reference dye RF1 with a decay time Tau > 1 µs.

[0067] The second functional section includes: - Indicator dyes with polyurethane BODIPY and decay times in the nanosecond range; and - The first reference dye RF1 with a decay time Tau > 1 µs.

[0068] The third functional section includes: - A second reference dye RF2 with polyurethane BODIPY decay time in the nanosecond range; - The first reference dye RF1 has a decay time Tau > 5 µs.

[0069] The fourth functional section includes: - Indicator dyes with polyurethane BODIPY; - A second reference dye RF2 with BODIPY and decay time in the ns range.

[0070] The fifth functional section contains an indicator dye IF with polyurethane BODIPY.

[0071] The sixth functional segment includes a second reference dye RF2 with a polyurethane BODIPY having a decay time in the nanosecond range.

[0072] The seventh functional segment includes, for example, a first reference dye RF1 embedded in polyurethane with a decay time Tau > 5 μs.

[0073] The photochemical pH sensor 1 is described as follows: The photochemical pH sensor 1 has a sensor body 2 and a sensor head 3. The sensor head 3 is preferably detachably fastened to the sensor body 2. The advantage of a detachable sensor head 3 is that it can be replaced without discarding the sensor body 2 if replacement is required. Therefore, the photochemical pH sensor 1 is also suitable for areas where, for example, a disposable sensor head is required.

[0074] The sensor head 3 includes the photochemical sensor element 10 described above according to the present invention.

[0075] The sensor body 2 and the sensor head 3 extend, for example, along the X-axis. The photochemical sensor element 10 preferably extends laterally relative to the X-axis (see [link]). Figure 5 ) or extending circumferentially relative to the X-axis (see Figure 6 If the photochemical sensor element 10 extends laterally relative to the X-axis, then the layer of the photochemical sensor element 10 is traversed by the X-axis. If the photochemical sensor element 10 extends circumferentially relative to the X-axis, then the layer of the photochemical sensor element 10 is arranged concentrically around the X-axis, for example.

[0076] like Figures 5-7 As shown in the example, the sensor body 2 includes a light source 4, a photodetector 6, and a control unit 7. The control unit 7 is connected to the light source 4 and the photodetector 6. The control unit 7 is adapted to control the light source 4 and evaluate the signal detected by the photodetector 6.

[0077] The light source 4 is adapted to emit at least one stimulation signal S1 in such a manner that the functional layer 30 is illuminated by the stimulation signal S1. The light source 4 is, for example, an LED or an LED array. The stimulation signal is guided onto the functional layer 30, for example, via an optical waveguide 5.

[0078] The photodetector 6 is adapted to detect the light emission signals L1, L2, and L3 emitted by the functional layer 30. The photodetector 6 is, for example, a spectrometer, a CCD camera, or other detector.

[0079] If the light-emitting signals L1, L2, and L3 have different wavelengths, the control unit 7 is adapted, for example, to filter the light-emitting signals L1, L2, and L3 detected by the photodetector 6.

[0080] exist Figure 5 and Figure 6In the illustrated embodiment, the photochemical pH sensor 1 further comprises a stimulation filter unit 8 and a detection filter unit 9. The stimulation filter unit 8 is adapted to filter the stimulation signal generated by the light source 4 in such a manner that a first stimulation signal S1, a second stimulation signal S2, or a third stimulation signal S3, each having a different wavelength, are generated. Of course, if the light source 4 is adapted to generate different stimulation signals with different wavelengths, the stimulation filter unit 8 is not needed. The detection filter unit 9 is adapted to filter superimposed emission signals with different wavelengths. Of course, if the emission signals arrive at the photodetector 6 with a time delay, i.e., they are not superimposed, the detection filter unit 9 is not needed. If the photodetector 6 can quantize the detected superimposed emission signals of different wavelengths according to the wavelength of the detected emission signal, the detection filter unit 9 is also not needed, as is the case with a spectrometer, for example.

[0081] exist Figure 5 and Figure 6 In the illustrated embodiment, the photodetector 6 has a detection filter unit 9 adapted to filter a first emission signal L1 emitted by the first reference dye RF1, a second emission signal L2 emitted by the second reference dye RF2, and a third emission signal L3 emitted by the indicator dye IF. The photodetector 6 is sensitive, for example, to radiation in the wavelength range of 600 nm to 1100 nm.

[0082] exist Figure 7 In the illustrated embodiment, the optical waveguide 5 includes four conductor fibers 51, 52, 53, and 54. Thus, for example, an LED array can generate four independent stimulation signals S1, S2, S3, and S4. The first conductor fiber 51 is arranged such that the first stimulation signal S1 is directed to a first functional segment 31; the second conductor fiber 52 is arranged such that the second stimulation signal S2 is directed to a second functional segment 32; the third conductor fiber 53 is arranged such that the third stimulation signal S3 is directed to a third functional segment 33; and the fourth conductor fiber 54 is arranged such that the fourth stimulation signal S4 is directed to a fourth functional segment 34.

[0083] Figure 7The optical waveguide 5 shown is, for example, a Y-shaped optical waveguide 5. This means that each conductor fiber 51, 52, 53, 54 has a junction. One branch of the junction extends to the light source 4 (shown as a dashed line), and the other branch of the junction extends to the photodetector 6. The common portion of the Y-shaped optical waveguide 5 extends to a dedicated section. Thus, for example, the first stimulation signal S1 can be guided via the first conductor fiber 51 to the first functional section 31, and the first emission signal L1 can be guided via the first conductor fiber 51 to the photodetector 6. The optical waveguide 5 has the same structure in all the other conductor fibers 52, 53, and 54.

[0084] like Figure 7 As can be seen, the photochemical sensor element 10 is circular, and the functional segments 31, 32, 33, and 34 are defined by the radial sub-regions of the functional layer 30. The functional layer 30 is coated on the first substrate side 21 of the substrate layer 20. A selection layer 40 is mounted on the functional layer 30, such that the selection layer 40 is adapted to contact the measurement medium.

[0085] Figure 6 An embodiment of the photochemical pH sensor 1 is shown, wherein the photochemical sensor element 10 extends radially relative to the X-axis defined by the sensor body 2 and the sensor head 3. The photochemical sensor element 10 is arranged, for example, in a ring shape within the sensor head 3. For example, the sensor head 3 is sleeve-shaped, and the photochemical sensor element 10 is disposed on the inner surface of the sensor head 3. In this embodiment, the optical waveguide 5 includes corresponding guide portions 56, thereby conducting the stimulation signal from the light source 4 to the functional layer 30 and conducting the emission signal from the functional layer 30 to the photodetector 6. The radial arrangement of the functional layer 30 has the advantage of more easily manufacturing the sensor sub-units, such as the functional segments, using conventional methods such as scraping and spraying. Clear separation of the individual functional segments or comparison segments prevents crosstalk between the emission signals generated by the functional segments or comparison segments. Individual detection of different emission signals simplifies the processing of the corresponding emission signals. Here, simpler processing means that simpler formulas can be used to evaluate signal measurements. The simpler formulas result in less computation and lower memory requirements (because fewer memory locations are needed for parameters, coefficients, modulation frequencies, etc.).

[0086] The method for measuring pH using the aforementioned photochemical pH sensor 1 will be discussed below. An example of the photochemical pH sensor 1 with functional layer 30 will be described below, such as... Figure 1 As shown.

[0087] In the first step, the photochemical pH sensor 1 is provided. This means that the photochemical pH sensor 1 is functional and in contact with the measurement medium.

[0088] Subsequently, the control unit 7 controls the light source 4, causing the light source 4 to emit a first stimulation signal S1 onto the functional layer 30. The first stimulation signal S1 preferably has a wavelength in the range of 200 nm to 600 nm, more preferably 400 nm to 600 nm.

[0089] The first reference dye RF1, the second reference dye RF2, and the indicator dye IF are stimulated by the first stimulus signal S1, i.e., they are excited and emit light signals. The first reference dye RF1 emits a first light signal L1, the second reference dye RF2 emits a second light signal L2, and the indicator dye IF emits a third light signal L3. Preferably, the light signals each have a different wavelength.

[0090] The first emission signal L1, the second emission signal L2, and the third emission signal L3 are then detected using the photodetector 6. The photodetector 6 is adapted, for example, to analyze the spectrum of the detected radiation, so that the control unit 7 can identify and filter emission signals of different wavelengths.

[0091] In the next step, the detected light emission signals L1, L2, and L3 are evaluated by the control unit 7. This step includes, for example, filtering different light emission signals by the control unit 7 so that the light emission signals L1, L2, and L3 exist individually.

[0092] The control unit 7 compares the first light emission signal L1 emitted by the first reference dye RF1 with the second light emission signal L2 emitted by the second reference dye RF2. The comparison of the light emission signals includes, for example, comparing the amplitude (or phase difference / attenuation time) or integral of the signals of the first light emission signal L1 and the second light emission signal L2.

[0093] Then, the reference signal difference between the first luminescent signal L1 generated by the first reference dye RF1 and the second luminescent signal L2 generated by the second reference dye RF2 is determined.

[0094] Next, the measurement signal difference between the first emission signal L1 and the third emission signal L3 is determined. This measurement signal difference depends on the pH value of the measurement medium. Therefore, the current pH value of the measurement medium can be derived from the measurement signal difference.

[0095] When the photochemical sensor element 10 experiences drift due to aging, such as distortion of the measurement signal difference and the resulting pH value of the measurement medium, drift compensation is required. This drift compensation can be performed using a determined reference signal difference.

[0096] For example, if the photochemical sensor element 10 does not drift, the reference signal difference is equal to zero. In this case, the measurement signal difference is multiplied by a drift factor equal to 1, thus disregarding drift.

[0097] However, if, for example, there is a drift in the photochemical sensor element 10, the reference signal difference is not equal to zero or preferably greater than a predetermined limit. In this case, the measured signal difference is multiplied by a drift factor not equal to 1 to compensate for the drift. The drift of the indicator dye IF is thus identified due to the reference signal difference (dual lifetime reference) or the reference signal ratio (ratio measurement).

[0098] The pH value is then determined based on the determined difference between the measured signal and the reference signal, i.e., the determined drift factor.

[0099] Drift compensation enables the photochemical pH sensor 1 to be used even in the presence of drift in the photochemical sensor element 10, and to simultaneously determine the reliable pH value of the measurement medium. Therefore, the photochemical pH sensor 1 can be used for a longer period of time, is more reliable, and can measure the pH value of the measurement medium more accurately than conventional sensors.

[0100] In one embodiment, the method further includes the step of outputting a warning message using the control unit 7 if the reference signal difference exceeds a predetermined limit. This informs the user that drift exists and has been compensated for. Depending on the intensity of the drift, if the limit is exceeded, a request to replace the sensor head 3 can also be output. Here, for example, the change in the measured value is measured at a defined temperature over a certain time interval. The control unit 7 is adapted to store measurement data and / or improve the measurement data based on the identified drift. By replacing the sensor head 3, the photochemical sensor element 10 can be replaced along with the aged functional layer 30.

[0101] In an alternative embodiment, the photodetector 6 has an integrated detection filter to filter the emission signals L1, L2, L3. In this case, the photodetector 6 preferably has multiple detection regions, for example, through different pixels. The detection filters are preferably arranged such that a particular detection filter is upstream of a particular detection region, so that each detection region is suitable for detecting different emission signals.

[0102] In an alternative embodiment, the photodetector 6 has a detection filter unit 9 preceding the photodetector 6 (see [link]). Figure 5 and Figure 6 The detection filter unit 9 makes it possible to separate different light emission signals.

[0103] In an alternative embodiment, the light source 4 emits at least three different stimulation signals, each with a different wavelength. The light source 4 emits the stimulation signals simultaneously or sequentially.

[0104] In an alternative embodiment, the light source 4 is configured as an array of multiple LEDs and utilizes stimulation signals with different LED emission time delays.

[0105] Depending on whether the light source 4 has multiple independently controllable LEDs, the control of the light source 4 can be adapted so that one or more stimulus signals are emitted simultaneously or independently.

[0106] Depending on whether the photodetector 6 has multiple detection areas, the detection filter unit 9 and the light source 4 can be used to adapt the detection of the light emission signal performed by the photodetector 6, so that the light emission signal can be processed individually.

[0107] In one embodiment, the photochemical sensor element 10 includes a functional layer 30 having a single segment.

[0108] The aforementioned ratio measurement method will now be discussed. In this method, the emission signals emitted by the dyes (first reference dye RF1, second reference dye RF2, and indicator dye IF) are compared with each other. Specifically, the amplitude and time curve of the emission signals are compared. Thus, a reference signal ratio is obtained. If the ratio is equal to 1, there is no drift. If the ratio is less than 1, drift exists.

[0109] The determined pH value is corrected based on the drift determined by the ratio measurement method.

[0110] Some mathematical formulas related to the ratio measurement method are shown below: (Formula 1.0) (Formula 1.1) (Formula 1.2) (Formula 1.3) (Formula 2.0) Explanation of the formula for the ratio measurement method: - Ratio pH response (F1 can be IF, F2 can be reference dye); - The asymptotic minimum and maximum values ​​of the sigmoid functions α1(t) and α2(t); - α3(t) = pKa value of the indicator (inflection point of the sigmoid function); - α4(t) = a constant describing the slope between α1(t) and α2(t) of the sigmoid function; - Cal = the measurement at time t0 or ti; - D = Drift.

[0111] To correct for drift over time, calibration data at time point t0 before test series (Cal1) is linked to calibration data at time point t1 after test series (Cal2) (see Equation 2.0 above). Correction can be performed during continuous sensor operation, rather than calibration. For example, aging of the less stable organic reference dye RF2 can be used as a correction method, as it also provides different signals at different measurement times, independent of analyte concentration. Drift correction can be performed on the entire term or only on a single parameter. For example, only the values ​​α1(t) and α2(t) can be corrected. For example, when using polynomials, linear functions, or e^(-t / t), the correction can be performed. x Other possibilities for drift correction are possible under the condition of the function.

[0112] (Formula 3.0)

[0113] As an alternative to the ratio measurement method, the so-called dual lifetime reference (DLR) can also be applied.

[0114] The calibration curve is fitted and displayed as a Boltzmann sigmoid function. The simplest form is shown below: (Formula 4.0) However, taking into account the effects of temperature and / or salinity, the function can also be expressed as follows: (Formula 5.0) (Formula 6.0) illustrate: - Bottom = Minimum limit value of calibration (cot) ) - TOP = Maximum limit value of calibration (cot) ) - V50 = inflection point, the pKa value of the indicator (the inflection point of the sigmoid function). - Slope = the slope at the inflection point - T = Temperature - S = Salinity - B t T t V50 t =Linear temperature coefficient - B S T S V50 S =Linear salinity coefficient Drift correction can be performed on both individual parameters and the entire term. This depends on the choice of dye. In some cases, the correction may also include coefficients dependent on temperature and salinity (see dual lifetime reference). It does not necessarily need to be a linear function as shown in the equation. Alternatively, it can be, for example, a polynomial or e^(-π / 2). x function.

[0115] The phase angle shift between the stimulation signals S1, S2, S3 and the detected emission signals L1, L2, L3 can also be evaluated by the photodetector 6.

[0116] List of labels

Claims

1. A photochemical sensor element (10) for a photochemical pH sensor (1), comprising: - A substrate layer (20) having a first substrate side (21) facing the measuring medium and a second substrate side (22) opposite to the first substrate side (21); - A functional layer (30), which is disposed on the first substrate side (21) and has a first reference dye (RF1), an indicator dye (IF), and a second reference dye (RF2) different from the first reference dye (RF1). The first reference dye (RF1) comprises an inorganic material and is pH insensitive, and is adapted to emit a first luminescent signal (L1) upon stimulation with a first stimulus signal (S1). The indicator dye (IF) comprises an organic material and is pH sensitive, and is adapted to emit a third luminescent signal (L3) upon stimulation with the first stimulus signal (S1). The second reference dye (RF2) comprises an organic material and is pH insensitive, and has the indicator dye (IF) reacted by esterification, etherification, or amidation, and is adapted to emit a second luminescent signal (L2) upon stimulation with the first stimulus signal (S1). The substrate layer (20) is transparent to the stimulation signal (S1) and the light emission signal (L1, L2, L3). The stability of the second reference dye (RF2) differs from that of the first reference dye (RF1), enabling the acquisition of the reference signal difference or reference signal ratio for determining drift compensation.

2. The photochemical sensor element (10) according to claim 1, wherein the functional layer (30) is subdivided into at least two functional segments (31, 32), The first functional section (31) includes the first reference dye (RF1), the indicator dye (IF), and the second reference dye (RF2). The second functional section (32) includes the first reference dye (RF1) and the indicator dye (IF). Or the first reference dye (RF1) and the second reference dye (RF2), Or the indicator dye (IF) and the second reference dye (RF2).

3. The photochemical sensor element (10) according to claim 1 or 2, wherein a comparison layer (60) having a first comparison section (61) is disposed on the second substrate side (22) of the substrate layer (20), wherein the first comparison section (61) has the first reference dye (RF1), the second reference dye (RF2) or the indicator dye (IF).

4. The photochemical sensor element (10) according to claim 3, wherein the comparison layer (60) has a plurality of comparison segments, wherein each comparison segment has the first reference dye (RF1), the second reference dye (RF2) or the indicator dye (IF).

5. The photochemical sensor element (10) according to claim 1 or 2, wherein the functional layer (30) is subdivided into at least three functional segments (31, 32, 33), wherein the first functional segment (31) has the first reference dye (RF1), the second functional segment (32) has the indicator dye (IF), and the third functional segment (33) has a second reference dye (RF2) that is different from the first reference dye (RF1) and has the indicator dye (IF) reacted by esterification, etherification or amidation.

6. The photochemical sensor element (10) according to claim 1 or 2, wherein the functional layer (30) has more than three functional segments and each functional segment has different dyes (RF1, RF2, IF) or different combinations of dyes (RF1, RF2, IF).

7. The photochemical sensor element (10) according to claim 1 or 2, wherein the functional layer (30) is circular and subdivided into four functional segments (31, 32, 33, 34) formed by radial sub-regions of the functional layer (30), or The functional layer (30) is rectangular and subdivided into four functional sections (31, 32, 33, 34) formed by the rectangular sub-parts of the functional layer (30).

8. The photochemical sensor element (10) according to claim 1 or 2, wherein the functional layer (30) has a proton-conducting matrix and the first reference dye (RF1) and / or the indicator dye (IF) and / or the second reference dye (RF2) are uniformly arranged in the proton-conducting matrix.

9. The photochemical sensor element (10) according to claim 1 or 2, wherein the photochemical sensor element (10) further comprises a selection layer (40) disposed on the side of the functional layer (30) opposite to the substrate layer (20) and is permeable to protons.

10. The photochemical sensor element (10) according to claim 9, wherein the functional segments are respectively in contact with the substrate layer (20) or another layer on a first side surface and in contact with the selection layer (40) or another layer or measurement medium on a second side surface opposite to the first side surface.

11. The photochemical sensor element (10) according to claim 1 or 2, wherein the first reference dye (RF1) has a material selected from the group consisting of titanates, nitrides, gallates, sulfides, sulfates, aluminates, and silicates.

12. The photochemical sensor element (10) according to claim 1 or 2, wherein the first reference dye (RF1) has a material selected from: Han blue, Han violet, Egyptian blue, ruby ​​red, aluminum borate, chromium yttrium aluminum borate, gadolinium aluminum borate, manganese IV activated magnesium titanate, manganese IV activated magnesium fluorogermanate, ruby, emerald green and / or europium III activated yttrium oxide.

13. The photochemical sensor element (10) according to claim 1 or 2, wherein the indicator dye (IF) has a material or mixture selected from the following: BODIPY, aza-BODIPY, porphyrin, phthalocyanine, sterically hindered coumarin, perylene diimide, anthocyanin, diketopyrrolopyrrole (DPP), quinacridone (QD), 7-[2-(decyloxycarbonyl)-phenyl]-10-diethylamino-3-hydroxy-benzo[c]xanthanium Perchlorate (XP), azidiotrigonene (ADOTA), diazaoxatrigonene (DAOTA), hydroxypyrene sulfonic acid (HPTS), 6,8-dihydroxypyrene-1,3-disulfonic acid (DHPDS), fluorescein and its derivatives.

14. The photochemical sensor element (10) according to claim 1 or 2, wherein the photochemical sensor element (10) has at least one additional layer disposed on the substrate layer (20) and / or the functional layer (30), wherein the additional layer is a protective layer, a darkening layer, a support layer or a barrier layer.

15. The photochemical sensor element (10) according to claim 9, wherein the photochemical sensor element (10) has at least one additional layer disposed on the substrate layer (20) and / or the functional layer (30) and / or the selection layer (40), wherein the additional layer is a protective layer, a darkening layer, a support layer or a barrier layer.

16. A photochemical pH sensor (1), said photochemical pH sensor (1) comprising: - Sensor body (2), the sensor body (2) having a light source (4), a photodetector (6) and a control unit (7), The control unit (7) is connected to the light source (4) and the photodetector (6), and is adapted to control the light source (4) and evaluate the signal detected by the photodetector (6); - A sensor head (3) having a photochemical sensor element (10) according to any one of claims 1 to 15; The sensor body (2) and the sensor head (3) are arranged such that the light source (4) is adapted to emit at least one stimulation signal (S1) in such a way that the photochemical sensor element (10) is irradiated by the stimulation signal (S1). The photodetector (6) is adapted to detect the light emission signals (L1, L2, L3) emitted by the photochemical sensor element (10).

17. The photochemical pH sensor (1) according to claim 16, wherein the photodetector (6) has a filter unit adapted to filter a first luminescence signal (L1) emitted by the first reference dye (RF1), a second luminescence signal (L2) emitted by the second reference dye (RF2) and a third luminescence signal (L3) emitted by the indicator dye (IF).

18. The photochemical pH sensor (1) according to claim 16 or 17, wherein the photochemical pH sensor (1) further comprises an optical waveguide (5) including at least two conductive fibers (51, 52), and the light source (4) is adapted to generate at least two independent stimulation signals (S1, S2). The first conductor fiber (51) is arranged such that the first stimulation signal (S1) is directed to the first functional segment (31). Furthermore, the second conductor fiber (52) is arranged such that the second stimulation signal (S2) is directed onto the second functional segment (32).

19. The photochemical pH sensor (1) according to claim 18, wherein the optical waveguide (5) has a fourth conductor fiber (54) and a comparison section (70) disposed at one end of the fourth conductor fiber (54).

20. A method for measuring the pH value of a measurement medium using a photochemical pH sensor (1), comprising at least the following steps: - Provides a photochemical pH sensor (1) according to any one of claims 16 to 19, - The control unit (7) controls the light source (4) so ​​that a first stimulation signal (S1) is emitted onto the photochemical sensor element (10) to stimulate the first reference dye (RF1), the second reference dye (RF2), and the indicator dye (IF). - The first emission signal (L1), the second emission signal (L2), and the third emission signal (L3) are detected using the photodetector (6). - The control unit (7) compares the first light emission signal (L1) emitted by the first reference dye (RF1) with the second light emission signal (L2) emitted by the second reference dye (RF2). - Determine the reference signal difference or reference signal ratio between the first light-emitting signal (L1) and the second light-emitting signal (L2). - Determine drift compensation using the determined reference signal difference or reference signal ratio. - Determine the measurement signal difference or measurement signal ratio between the first emission signal (L1) and the third emission signal (L3). - The pH value of the measurement medium is determined based on the determined drift compensation.

21. The method according to claim 20, wherein if the measurement signal difference, the reference signal difference, the measurement signal ratio, or the reference signal ratio exceeds or falls below a predetermined limit value, the control unit (7) outputs a warning message.

22. The method according to claim 20 or 21, wherein the photochemical pH sensor (1) further comprises an optical waveguide (5) having at least two conductive fibers (51, 52), and the light source (4) is adapted to generate at least two independent stimulation signals (S1, S2). The first conductor fiber (51) is arranged such that the first stimulation signal (S1) is directed to the first functional segment (31). Furthermore, the second conductor fiber (52) is arranged such that the second stimulation signal (S2) is directed onto the second functional segment (32). The step of controlling the light source (4) using the control unit (7) is performed in such a way that a first stimulation signal (S1) is emitted onto a first functional segment (31) using the first conductor fiber (51), and a second stimulation signal (S2) is emitted onto a second functional segment (32) using the second conductor fiber (52) in a time-delayed manner or simultaneously with the first stimulation signal (S1).

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