pH MEASUREMENT DEVICE AND pH MEASUREMENT METHOD

Abstract

This pH measurement device comprises: target matter which contains a pH indicator and a substance that causes a pH value to vary; reference matter to which a pH indicator has been added; an illumination unit (1) which irradiates at least one of the reference matter and the target matter with light; a detection unit which, from among light emitted from the illumination unit (1), detects the intensity of at least one of first light that has passed through the target matter and second light that has passed through the reference matter; and an estimation unit which estimates the pH value of the target matter on the basis of the results of detection by the detection unit.

Description

pH measuring device and pH measuring method

[0001] The present disclosure relates to a pH measurement device and a pH measurement method for measuring the pH value of an object.

[0002] pH measurement has traditionally been used as a method for determining the state of a solution. For example, in the field of cell biology, pH measurement is used to determine the degree of cell growth or proliferation when culturing cells. When cells grow or proliferate in a culture medium, acidic waste products such as lactic acid are produced, causing the pH value of the culture medium to decrease. Therefore, the state of the cells and the culture medium can be determined by utilizing changes in the pH value.

[0003] In general pH measurements, a pH electrode is immersed in a solution and the pH value is calculated by measuring the hydrogen ion concentration. However, in cell cultures performed under sterile conditions, direct contact of a pH electrode with the culture medium can lead to contamination. Therefore, it is necessary to measure the pH value using a method that does not contact the culture medium. For example, Patent Documents 1 and 2 estimate the pH value by acquiring optical data from a culture medium containing a pH indicator.

[0004] Patent No. 7417619 Patent No. 5797911

[0005] In Patent Documents 1 and 2, in order to measure pH, it is necessary to prepare data (a calibration curve or a database) in advance that correlates the optical data of the culture medium (color change of the pH indicator) with the pH value. However, unless data matching measurement conditions such as the optical path length of the optical system, the type, concentration, and temperature of the pH indicator are prepared, the pH value cannot be measured accurately. In addition, it is difficult to prepare data for each measurement condition. Furthermore, errors in the measurement conditions may reduce the accuracy of the pH value measurement.

[0006] Therefore, an object of the present disclosure is to provide a pH measurement device and a pH measurement method that can measure the pH value of an object in a non-contact manner with high accuracy.

[0007] In order to achieve the above object, a pH measuring device according to one embodiment of the present disclosure includes an object containing a substance that changes the pH value and a pH indicator, a reference object to which the pH indicator has been added, an illumination unit that irradiates light onto at least one of the reference object and the object, a detection unit that detects the intensity of at least one of first light that has passed through the object and second light that has passed through the reference object, out of the light irradiated from the illumination unit, and an estimation unit that estimates the pH value of the object based on the detection result of the detection unit.

[0008] According to the present disclosure, the pH value of an object can be measured contactlessly and with high accuracy.

[0009] 1 is a schematic diagram of a pH measurement device according to a first embodiment; a flowchart showing the flow of a pH value estimation process according to the first embodiment; a graph showing the relationship between a change in absorbance and a change in pH in a phenol red reagent; a schematic diagram of a pH measurement device according to a second embodiment; a schematic diagram of a pH measurement device according to a third embodiment; a schematic diagram of a pH measurement device according to a fourth embodiment; a schematic diagram of a pH measurement device according to a fifth embodiment; a flowchart showing the flow of a pH value estimation process according to the fifth embodiment; a schematic diagram of a pH measurement device according to a sixth embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or uses.

[0011] (First embodiment) Fig. 1 shows a schematic configuration diagram of a pH measurement device according to the first embodiment. As shown in Fig. 1, the pH measurement device according to the first embodiment includes an illumination unit 1, culture vessels 2 and 3, an optical data acquisition unit 4 (detection unit), a first processing unit 5, a pH adjustment unit 6, a pH electrode 7 (pH measurement unit), a pH meter 8 (pH measurement unit), and a second processing unit 9 (estimation unit).

[0012] The illumination unit 1 includes one light source 11 and an optical device 12 (first optical device). The light source 11 is a light source configured, for example, by an LED, a laser, a halogen light source, or the like. The optical device 12 is an optical device (optical component) that splits light, such as a beam splitter or a half mirror, and splits the light emitted from the light source 11 and irradiates the light in multiple directions. In this embodiment, the light irradiated from the light source 11 is split by the optical device 12 into incident light I １ , I ２ It is divided into

[0013] Incubation vessel 2 contains solution A (target) to be measured. Incubation vessel 3 contains solution B (reference) used to estimate (reference) the pH value of solution A. Incubation vessels 2 and 3 are common containers, and are made of a material that has little effect on transmitted light. For example, when measuring optical data of a solution in the visible light range, a colorless, transparent, thin container with low visible light absorbance is used.

[0014] Incident light I １ After passing through the culture vessel 2 (solution A), the transmitted light T １ The incident light I (first light) enters the switching device 41 of the optical data acquisition unit 4. ２ After passing through the culture vessel 3 (solution B), the transmitted light T ２ The incident light I (second light) enters the switching device 41 of the optical data acquisition unit 4. １ For example, an optical fiber, a mirror, or the like may be disposed in the transmission path.

[0015] Solution A, the object of pH measurement, contains a substance that changes the pH value of cells, etc., medium components, and a pH indicator, such as phenol red reagent, at a known concentration. Solution A is in the middle of culturing cells, etc. Note that, while Solution A is described as a solution containing a substance that changes the pH value, medium components, and a pH indicator, it is not limited to this, and may also be a solution containing a pH indicator in a reagent or body fluid.

[0016] The reference solution B contains a colorless, transparent buffer solution and a pH indicator. This buffer solution is, for example, a phosphate buffer solution prepared by mixing an aqueous solution of disodium hydrogen phosphate and an aqueous solution of potassium dihydrogen phosphate. The pH indicator is added in an amount adjusted so that the type and concentration are equal to those of the pH indicator contained in solution A. The initial pH value of solution B should be adjusted to a value similar to the pH value of solution A before use (medium before culture). While solution B is described as containing a buffer solution and a pH indicator, this is not limiting and solution B may contain a pH indicator in the liquid. Solution B may also contain the same solution components as solution A. For example, solution B may contain medium components and a pH indicator.

[0017] The optical data acquisition unit 4 includes a switching device 41 and a detector 42. The switching device 41 is a device, such as an optical switch, a mirror and an actuator, that switches the light incident on the detector 42 from the light incident from multiple directions. １ (Incoming light I １ ) and transmitted light T ２ (Incoming light I ２ ) is incident on the detector 42. The detector 42 is a light quantity sensor such as a spectroscope or a photodiode, and outputs optical data (electrical signals) of the incident light to the first processing unit 5. Note that the optical data acquisition unit 4 may be provided with a filter to adjust the light quantity or cut out unnecessary wavelength bands. Furthermore, for example, light intensity, transmittance, absorbance, reflectance, refractive index, etc. are used as the optical data as appropriate.

[0018] The first processing unit 5 is, for example, a microcomputer equipped with a CPU, a memory, etc. The first processing unit 5 outputs a control signal to the pH adjusting unit 6 based on the optical data output from the optical data acquiring unit 4.

[0019] The pH adjusting unit 6 adjusts the pH value of the solution B in response to a control signal from the first processing unit 5. Specifically, the pH adjusting unit 6 includes containers 61 and 62, pumps 63 and 64, and pipelines 65 and 66.

[0020] Container 61 contains solution C (first substance), and container 62 contains solution D (second substance).

[0021] Solution C contains the acid component of the buffer solution contained in Solution B and a pH indicator. In this embodiment, an aqueous solution of potassium dihydrogen phosphate is used as the acid component of the buffer solution. The pH indicator is added in an amount adjusted so that the type and concentration are the same as those of the pH indicator contained in Solution A.

[0022] Solution D contains the base component of the buffer solution contained in Solution B and a pH indicator. In this embodiment, an aqueous solution of disodium hydrogen phosphate is used as the base component of the buffer solution. The pH indicator is added in an amount adjusted so that the type and concentration are the same as those of the pH indicator contained in Solution A.

[0023] Container 61 is connected to culture vessel 3 through pipeline 65. Container 62 is connected to culture vessel 3 through pipeline 66. pH adjustment unit 6 drives pump 63 in response to a control signal from first processing unit 5, thereby sending (inputting) solution C contained in container 61 into culture vessel 3 through pipeline 65. pH adjustment unit 6 drives pump 64 in response to a control signal from first processing unit 5, thereby sending (inputting) solution D contained in container 62 into culture vessel 3 through pipeline 66. This adjusts the pH value of solution B contained in culture vessel 3. Note that pumps 63 and 64 may be, for example, micropumps or other pumps capable of sending minute amounts of liquid. Pipelines 65 and 66 may be, for example, chemical-resistant tubing, biotubes, or other tubing resistant to the chemicals used.

[0024] The pH electrode 7 is immersed in solution B in the culture vessel 3 and outputs a signal corresponding to the pH value of solution B. The pH meter 8 measures the pH value of solution B from the output signal of the pH electrode 7. Since the pH electrode 7 and pH meter 8 measure the pH value of solution B by contact, those that correspond to the range of change in the pH value of solution B are used. Furthermore, since the measurement error and resolution of the pH electrode 7 and pH meter 8 are directly related to the accuracy of estimating the pH value of solution A, it is desirable to use those with high accuracy and high resolution.

[0025] The second processing unit 9 is, for example, a microcomputer equipped with a CPU, memory, etc. The second processing unit 9 estimates the pH value of solution A based on the measurement result of the pH value of solution B by the pH measuring device 8. The first processing unit 5 and the second processing unit 9 may be implemented as a single PC or the like capable of parallel processing.

[0026] (pH Value Estimation Process) FIG. 2 is a flowchart showing the flow of pH value estimation process according to the first embodiment.

[0027] First, the light source 11 of the illumination unit 1 emits light (step S1). The light emitted from the light source 11 of the illumination unit 1 is converted by the optical device 12 into incident light I １ , I ２ The incident light I １ The incident light I enters the culture vessel 2 (solution A). ２ The incident light I enters the culture vessel 3 (solution B). １ After passing through the culture vessel 2 (solution A), the transmitted light T １ The incident light I enters the switching device 41 of the optical data acquisition unit 4. ２ After passing through the culture vessel 3 (solution B), the transmitted light T ２ The light is incident on the switching device 41 of the optical data acquisition unit 4.

[0028] In step S1, the incident light I １ , I ２ The light intensities of the incident light I and the incident light B are set to be as equal as possible. １ , I ２ (Transmitted light T １ , T ２ ) are set so that the optical path lengths are the same. Also, the culture vessels 2 and 3 are installed so that external disturbance light is not incident on solutions A and B. For example, a light-shielding cover is used. Also, in order to improve the accuracy of measuring the pH value, it is advisable to take an optical path that avoids, as much as possible, non-measurement target substances (e.g., cells) that have high light absorption or reflectance in the solution. Specifically, if cells tend to precipitate in solution A, the incident light I １ In addition, it is also possible to filter out non-target substances and use a light path that removes the non-target substances.

[0029] Furthermore, by using only one light source for the illumination unit 1 and dividing the light using the optical device 12 to pass through the culture vessels 2 and 3, it is possible to prevent deterioration in the accuracy of pH measurement due to differences in the light intensity of the multiple light sources when multiple light sources are used.

[0030] The switching device 41 is configured to １ , T ２ Of these, transmitted light T １ The detector 42 detects only the transmitted light T １ The optical data α corresponding to the above is output to the first processing unit 5 (step S3).

[0031] After a certain period of time has passed, the switching device 41 switches the incident transmitted light T １ , T ２ Of these, transmitted light T ２ The detector 42 detects only the transmitted light T ２ In steps S2 to S5, the transmitted light T １ , T ２ The measurement conditions (exposure time, number of measurements, averaging, etc.) are set to be the same.

[0032] The first processing unit 5 determines whether the error between the optical data α and β output from the detector 42 is within an allowable range (step S6).

[0033] Specifically, the measurement location n (n is a natural number) for the optical data α and β is determined, and the wavelength or wave number λk (k = 1, 2, ..., n) is determined. The optical data of solution A corresponding to λk is defined as α(λk), and the optical data of solution B corresponding to λk is defined as β(λk).

[0034] In step S6, the similarity between the optical data α and β is determined. As a first determination, the absolute value of the difference between α(λk) and β(λk) at n locations is taken, the sum of the n values ​​is calculated, and it is determined whether the sum is equal to or less than a certain value γ. If the sum is equal to or less than γ, the optical data α and β are determined to be similar, and if the sum is equal to or greater than γ, they are determined to be different. Note that the method for determining the similarity between the optical data α and β is not limited to this, and other methods may be used.

[0035] If the first processing unit 5 determines that the error in the optical data α and β output from the detector 42 is not within the acceptable range (No in step S6), it outputs a control signal to the pH adjustment unit 6 and adds (pours) either solution C or solution D to solution B (step S7).

[0036] In step S7, the pH value of solution B relative to solution A is determined, i.e., the magnitude of the optical data α and β at the peak wavelength or wavenumber. Specifically, the difference between the optical data α(λp) of solution A and the optical data β(λp) of solution B at the peak wavelength or wavenumber λp is calculated and determined to be positive or negative. This determination determines whether solution C or solution D should be sent to solution B (incubation vessel 3). Specifically, when phenol red reagent is used as the pH indicator, the difference between the absorbance α(430) and the absorbance β(430) or the difference between the absorbance α(560) and the absorbance β(560) at peak wavelengths of 430 nm and 560 nm is calculated.

[0037] FIG. 3 is a graph showing the relationship between absorbance change and pH change in phenol red reagent. The absorbance at a wavelength of 430 nm decreases as the pH value increases, while the absorbance at a wavelength of 560 nm increases as the pH value increases. That is, at a wavelength of 430 nm, when the solution of α(430) - β(430) is positive, solution B has a higher pH value than solution A. Therefore, by adding (delivering) solution C, which contains an acid component, to solution B, the pH value of solution B can be brought closer to that of solution A. On the other hand, when the solution of α(430) - β(430) is negative, solution B has a lower pH value than solution A. Therefore, by adding (delivering) solution D, which contains a base component, to solution B, the pH value of solution B can be brought closer to that of solution A. Similarly, at a wavelength of 560 nm, when the solution of α(560) - β(560) is positive, Solution B has a lower pH value than Solution A, and therefore, by adding (delivering) Solution D, which contains a base component, to Solution B, the pH value of Solution B can be made closer to that of Solution A. On the other hand, when the solution of α(560) - β(560) is negative, Solution B has a higher pH value than Solution A, and therefore, by adding (delivering) Solution C, which contains an acid component, to Solution B, the pH value of Solution B can be made closer to that of Solution A.

[0038] In addition to the methods of steps S6 and S7, a method of calculating the ratio of optical data may be used, the optical data may be normalized as necessary, the distribution of optical data may be considered, or a method of changing the judgment value γ may be used.

[0039] After step S7, step S6 is executed again.

[0040] If the first processing unit 5 determines that the error between the optical data α and β output from the detector 42 is within the allowable range (Yes in step S6), the second processing unit 9 estimates the pH value of solution A (step S8). Specifically, the second processing unit 9 estimates the pH value of solution A from the measurement results of the pH value of solution B by the pH electrode 7 and the pH meter 8. As described above, in step S6, the optical data α indicating the pH value of solution A and the optical data β indicating the pH value of solution B are similar with an error within the allowable range. Because there is a correlation between the optical data corresponding to the concentration and type of pH indicator and the pH value, it can be said that the pH values ​​of solutions A and B are equal within a set error.

[0041] Second Embodiment Fig. 4 shows a schematic diagram of a pH measurement device according to a second embodiment. In Fig. 4, the configuration of the optical data acquisition unit 4 differs from that in Fig. 1, with a detector provided for each transmitted light and the switching device 41 omitted.

[0042] Specifically, the optical data acquisition unit 4 includes a detector 42a (first detector) and a detector 42b (second detector). The detectors 42a and 42b are light quantity sensors such as a spectrometer and a photodiode. The detector 42a detects transmitted light T １ The detector 42b detects the transmitted light T ２ The detector 42a detects the transmitted light T １ The detector 42b outputs the optical data of the incident transmitted light T ２ The optical data is output to the first processing unit 5.

[0043] In the configuration of Fig. 4, the switching device 41 is omitted from the optical data acquisition unit 4, and therefore steps S2 and S4 are omitted in the pH value estimation process of Fig. 2. Also, in step S3, the detector 42a detects the incident transmitted light T １ The optical data is output to the first processing unit 5. In step S5, the detector 42b detects the incident transmitted light T ２ The optical data is output to the first processing unit 5.

[0044] The configuration of FIG. 4 can also provide the same effect as that of FIG.

[0045] It is preferable that the detectors 42a and 42b have the same specifications so that no detection error occurs.

[0046] Third Embodiment Fig. 5 shows a schematic configuration diagram of a pH measurement device according to a third embodiment. In Fig. 4, the configuration of the illumination unit 1 differs from that in Fig. 1, in that a light source is provided for each incident light, and the optical device 12 is omitted.

[0047] Specifically, the illumination unit 1 includes a light source 11a (first light source) and a light source 11b (second light source). The light sources 11a and 11b are light sources configured with, for example, an LED, a laser, a halogen light source, or the like. The light source 11a irradiates the culture vessel 2 (solution A) with incident light I １ The light source 11b emits incident light I ２ is emitted.

[0048] In the configuration of FIG. 5 , the optical device 12 is omitted from the illumination unit 1. Therefore, in step S1 of the pH value estimation process of FIG. 2 , the light sources 11 a and 11 b of the illumination unit 1 direct incident light I １ , I ２ The incident light I １ After passing through the culture vessel 2 (solution A), the transmitted light T １ The incident light I enters the switching device 41 of the optical data acquisition unit 4. ２ After passing through the culture vessel 3 (solution B), the transmitted light T ２ The light is incident on the switching device 41 of the optical data acquisition unit 4.

[0049] The configuration of FIG. 5 can also provide the same effect as that of FIG.

[0050] The light sources 11a and 11b receive incident light I １ , I ２ It is preferable that the specifications are the same so that the light intensities of the two are the same.

[0051] (Fourth embodiment) Fig. 6 shows a schematic configuration diagram of a pH measurement device according to a fourth embodiment. In Fig. 6, the configurations of the illumination unit 1 and the optical data acquisition unit 4 differ from those in Fig. 1, and a light source and a detector are provided for each incident light (transmitted light), and the optical device 12 and the switching device 41 are omitted.

[0052] Specifically, the illumination unit 1 includes light sources 11a and 11b. The light sources 11a and 11b are light sources configured with, for example, an LED, a laser, a halogen light source, or the like. The light source 11a irradiates the culture vessel 2 (solution A) with incident light I １ The light source 11b emits incident light I ２ is emitted.

[0053] The optical data acquisition unit 4 includes detectors 42a and 42b. The detectors 42a and 42b are light intensity sensors such as a spectroscope and a photodiode. The detector 42a detects transmitted light T １ After passing through the incubation container 3 (solution B), the transmitted light T ２ The detector 42a detects the transmitted light T １ The detector 42b outputs the optical data of the incident transmitted light T ２ The optical data is output to the first processing unit 5.

[0054] In the configuration of FIG. 6, the optical device 12 and the switching device 41 are omitted. Therefore, in step S1 of the pH value estimation process of FIG. 2, the light sources 11a and 11b of the illumination unit 1 direct incident light I to the culture vessels 2 and 3 (solutions A and B). １ , I ２ The incident light I １ After passing through the culture vessel 2 (solution A), the transmitted light T １ The incident light I enters the detector 42a of the optical data acquisition unit 4. ２ After passing through the culture vessel 3 (solution B), the transmitted light T ２ The light is incident on the detector 42 b of the optical data acquisition unit 4 .

[0055] 2, steps S2 and S4 are omitted. In step S3, the detector 42a detects the incident transmitted light T １ The optical data is output to the first processing unit 5. In step S5, the detector 42b detects the incident transmitted light T ２ The optical data is output to the first processing unit 5.

[0056] The configuration of FIG. 6 also provides the same effect as that of FIG.

[0057] It is preferable that the detectors 42a and 42b have the same specifications so that no detection error occurs. １ , I ２ It is preferable that the specifications are the same so that the light intensities of the two are the same.

[0058] Fifth Embodiment Fig. 7 shows a schematic configuration diagram of a pH measurement device according to a fifth embodiment. In Fig. 7, the configuration of the illumination unit 1 differs from that in Fig. 1, in that an optical device 13 (second optical device) is provided instead of the optical device 12, and the switching device 41 is omitted.

[0059] Specifically, the optical device 13 is an optical device (optical component) that switches the direction of light, such as an optical switch, a mirror, and an actuator. In this embodiment, the light irradiated from the light source 11 is incident on the culture vessel 2 (solution A) by the optical device 13. １ and incident light I incident on the culture vessel 3 (solution B). １ It will be one of the two lights.

[0060] Fig. 8 is a flowchart showing the flow of the pH value estimation process according to the fifth embodiment. In Fig. 8, step S11 is executed instead of step S1, and step S12 is executed after step S3.

[0061] In step S11, the light source 11 of the illumination unit 1 irradiates the culture vessel 2 (solution A) with incident light I １ Specifically, the light emitted from the light source 11 of the illumination unit 1 is irradiated in a different direction by the optical device 13, and incident light I １The incident light I １ After passing through the culture vessel 2 (solution A), the transmitted light T １ The light is incident on the detector 42 of the optical data acquisition unit 4.

[0062] In step S12, the light source 11 of the illumination unit 1 irradiates the culture vessel 3 (solution B) with incident light I ２ Specifically, the light emitted from the light source 11 of the illumination unit 1 is irradiated in a different direction by the optical device 13, and incident light I ２ The incident light I ２ After passing through the culture vessel 3 (solution B), the transmitted light T ２ The light is incident on the detector 42 of the optical data acquisition unit 4.

[0063] The configuration of FIG. 7 can also provide the same effect as that of FIG.

[0064] The configuration of FIG. 7 may also be provided with a switching device 41.

[0065] Sixth Embodiment Fig. 9 shows a schematic diagram of a pH measuring device according to a sixth embodiment. In Fig. 9, the configuration of the optical data acquiring unit 4 differs from that in Fig. 7, and a detector is provided for each transmitted light.

[0066] Specifically, the optical data acquisition unit 4 includes detectors 42a and 42b. The detectors 42a and 42b are light quantity sensors such as a spectroscope and a photodiode. The detector 42a detects transmitted light T １ After passing through the incubation container 3 (solution B), the transmitted light T ２ The detector 42a detects the transmitted light T １ The detector 42b outputs the optical data of the incident transmitted light T ２ The optical data is output to the first processing unit 5.

[0067] In the configuration of FIG. 9, in step S3, the detector 42a detects the incident transmitted light T １ The optical data is output to the first processing unit 5. In step S5, the detector 42b detects the incident transmitted light T ２The optical data is output to the first processing unit 5.

[0068] The configuration of FIG. 9 also provides the same effect as that of FIG.

[0069] Other Embodiments As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate.

[0070] In each of the above embodiments, the illumination unit 1 may be provided with the optical device 12, and the optical data acquisition unit 4 may be provided with the switching device 41.

[0071] Furthermore, in each of the above embodiments, the light sources 11, 11a, and 11b are not limited to a single light source. For example, the light source 11 may include a single light source that outputs multiple wavelengths, or multiple light sources that output a single wavelength. Similarly, the detectors 42, 42a, and 42b are not limited to a single detector (sensor). For example, the detector 42 may include a spectrometer that can process multiple wavelengths, or multiple photodiodes that process a single wavelength.

[0072] In each of the above embodiments, the optical path length may be different for each incident light (transmitted light). The light detected by the detector may be light scattered within the culture vessels 2 and 3 (solutions A and B). The detector may also receive overlapping transmitted light (incident light).

[0073] In each of the above embodiments, the optical device 12 may polarize the light from the light source 11 instead of changing the direction of the light. In this case, the detector may receive a mixture of different transmitted light (incident light).

[0074] Furthermore, in each of the above embodiments, instead of changing the direction of light from the light source 11 using the optical device 12 or the optical device 13, the position of the culture vessels 2, 3 (solutions A, B) may be changed to obtain transmitted light through the culture vessels 2, 3 (solutions A, B).

[0075] In addition, although the above embodiment has been described using the example of measuring the pH of a culture medium in which cells are cultured, the present invention is not limited to this example and can be applied to any non-contact pH measurement, such as adjusting reagents, adjusting culture medium before culture, and measuring harmful substances.

[0076] The pH measurement device of the present disclosure can be used to measure the pH of an object (for example, a solution for culturing cells).

[0077] REFERENCE SIGNS LIST 1 Illumination unit 11 Light source 11a Light source (first light source) 11b Light source (second light source) 12 Optical device (first optical device) 13 Optical device (second optical device) 2, 3 Culture vessel 4 Optical data acquisition unit (detection unit) 41 Switching device 42 Detector 42a Detector (first detector) 42b Detector (second detector) 5 First processing unit 6 pH adjustment unit 61, 62 Container 63, 64 Pump 65, 66 Pipeline 7 pH electrode (pH measurement unit) 8 pH meter (pH measurement unit) 9 Second processing unit (estimation unit) I １ , I ２ Incident light T １ Transmitted light (first light) T ２ Transmitted light (second light) A Solution (object) B Solution (reference) C Solution (first substance) D Solution (second substance)

Claims

1. A pH measuring device comprising: an object containing a substance that changes the pH value and a pH indicator; a reference object to which the pH indicator has been added; an illumination unit that irradiates light onto at least one of the reference object and the object; a detection unit that detects the intensity of at least one of the first light that has passed through the object and the second light that has passed through the reference object, of the light irradiated from the illumination unit; and an estimation unit that estimates the pH value of the object based on the detection result of the detection unit.

2. The pH measuring device according to claim 1, further comprising: a pH measuring unit that measures the pH value of the reference substance; and a pH adjusting unit that adjusts the pH value of the reference substance based on the detection result of the detecting unit.

3. The pH measuring device according to claim 2, wherein the pH adjusting unit adds either a first substance that lowers the pH value of the reference substance or a second substance that raises the pH value of the reference substance to the reference substance based on the detection result of the detecting unit.

4. The pH measuring device according to claim 1, wherein the detection unit includes a detector that detects the intensity of at least one of the first light and the second light, and the detector receives light in which the first light and the second light are overlapped, or either the first light or the second light.

5. A pH measuring device as described in claim 1, wherein the detection unit comprises: a detector that detects the intensity of incident light; and a switching unit that switches the light incident on the detector to at least one of the first light and the second light.

6. The pH measuring device according to claim 1, wherein the detection unit comprises: a first detector that detects the light intensity of the first light; and a second detector that detects the light intensity of the second light.

7. The pH measuring device according to claim 1, wherein the illumination unit comprises: a light source; and a first optical device that splits the light emitted from the light source into the first light and the second light.

8. The pH measuring device according to claim 1, wherein the illumination unit comprises: a light source; and a second optical device that switches the light emitted from the light source to at least one of the first light and the second light.

9. The pH measuring device according to claim 1, wherein the illumination unit comprises: a first light source that irradiates the first light; and a second light source that irradiates the second light.

10. A pH measuring device as described in claim 1, wherein the first light is light that has passed through a portion of the object that contains a small proportion of non-measurement target substances that have a high light absorption or reflectance rate.

11. A pH measuring device as described in claim 10, wherein a solution containing the target substance is contained in a container, the container is provided with a filter that removes the non-target substances from the target substance, and the first light is light that has passed through a portion of the solution from which the non-target substances have been removed by the filter.

12. The pH measurement device according to claim 1, further comprising a pH measurement unit that measures the pH value of the reference substance, wherein the pH measurement unit measures the pH value of the reference substance by contacting the reference substance.

13. A pH measurement method comprising: an irradiation step of irradiating a target object containing a substance that changes the pH value and the pH indicator, and a reference object to which a pH indicator has been added, with light; a first detection step of detecting the light intensity of a first light, which is transmitted through the target object from the light irradiated from the illumination unit, using a detection unit; a second detection step of detecting the light intensity of a second light, which is transmitted through the reference light, from the light irradiated from the illumination unit, using the detection unit; and an estimation step of estimating the pH value of the target object based on the detection results of the first and second detection steps.

14. The pH measurement method according to claim 13, further comprising: a pH measurement step of measuring the pH value of the reference substance; and a pH adjustment step of adjusting the pH value of the reference substance so that the light intensity of the first light and the light intensity of the second light are substantially the same.

15. The pH measurement method according to claim 14, wherein the pH adjustment step includes at least one of a pH decrease adjustment step for decreasing the pH value of the reference substance and a pH increase adjustment step for increasing the pH value of the reference substance based on the detection result of the detection unit.

16. The pH measurement method according to claim 13, wherein the detection unit comprises a detector that detects the intensity of incident light and a switching unit, and the method further includes a switching step in which the switching unit switches the light incident on the detector to at least one of the first light and the second light.

17. The pH measurement method according to claim 13, wherein the first detection step and the second detection step are carried out simultaneously.

18. The pH measurement method according to claim 13, wherein in the irradiation step, the illumination unit splits the light emitted from the light source into the first light and the second light.

19. A pH measurement method as described in claim 13, wherein the first light is light that has passed through a portion of the object that contains a small proportion of non-measurement target substances that have a high light absorption or reflectance rate.

20. A pH measurement method as described in claim 19, further comprising a filtering step of removing the non-measurement target substances from the object using a filter, wherein the first light is light that has passed through a portion of the solution from which the non-measurement target substances have been removed by the filter.

21. The pH measurement method according to claim 13, further comprising a pH measurement step of measuring the pH value of the reference substance, wherein the pH value of the reference substance is measured by a pH electrode in contact with the reference substance in the measurement step.

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