US20150355134A1 - Ph value measuring device comprising in situ calibration means - Google Patents

Ph value measuring device comprising in situ calibration means Download PDF

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Publication number
US20150355134A1
US20150355134A1 US14/763,252 US201414763252A US2015355134A1 US 20150355134 A1 US20150355134 A1 US 20150355134A1 US 201414763252 A US201414763252 A US 201414763252A US 2015355134 A1 US2015355134 A1 US 2015355134A1
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Prior art keywords
value
measuring
effluent
modifying
calibrating
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Yves de Coulon
Carine Beriet
Cyrille Lemoine
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Veolia Eau Compagnie Generale des Eaux SCA
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Veolia Water Solutions and Technologies Support SAS
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Assigned to VEOLIA WATER SOLUTIONS & TECHNOLOGIES SUPPORT reassignment VEOLIA WATER SOLUTIONS & TECHNOLOGIES SUPPORT ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: LEMOINE, CYRILLE, BERIET, CARINE, DE COULON, YVES
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/333—Ion-selective electrodes or membranes
    • G01N27/3335—Ion-selective electrodes or membranes the membrane containing at least one organic component
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/302—Electrodes, e.g. test electrodes; Half-cells pH sensitive, e.g. quinhydron, antimony or hydrogen electrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/4163—Systems checking the operation of, or calibrating, the measuring apparatus
    • G01N27/4165—Systems checking the operation of, or calibrating, the measuring apparatus for pH meters

Definitions

  • the field of the invention is that of techniques for measuring the value of the pH of a liquid effluent.
  • the invention pertains to the designing and manufacture of probes and to a method for the continuous measurement of the value of the pH of a liquid effluent.
  • pH Potential hydrogen, more commonly called pH, represents the chemical activity of hydrogen ions in solution.
  • the value of the pH of a solution reveals its acidity or its basicity.
  • the pH is a parameter used in many applications.
  • the pH is for example used in water treatment where it is an indicator, for example of the healthy biological condition of water. It is also often used as a control parameter when implementing water treatment methods.
  • Glass electrode probes are relatively brittle and require daily or weekly maintenance operations, especially because the glass electrode contains an electrolyte, which is a consumable. This drawback can be reduced through the use of electrolyte in the form of gel but cannot be completely removed. Besides, the storage of glass electrodes implies compliance with special and constraining conditions. Indeed, glass electrodes have to be stored in a potassium chloride solution since dry storage induces premature ageing.
  • Non-glass electrode probes have especially been developed in order to overcome these drawbacks.
  • the invention relates more particularly but not exclusively to non-glass electrode pH measuring probes.
  • non-glass electrode pH measuring probes classically comprise an ISFET (Ion-Sensitive Field Effect Transistor) type transistor and a reference electrode 15 .
  • ISFET Ion-Sensitive Field Effect Transistor
  • the gate 13 has a layer sensitive to variations in H + ion concentration.
  • the reference electrode 15 can be constituted by a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) type transistor.
  • MOSFET Metal Oxide Semiconductor Field Effect Transistor
  • the source 11 and the drain 12 are connected to a generator 16 of electric voltage and electric current capable of generating a voltage and an electric current of constant values at their terminals.
  • the reference electrode 15 and the source 11 are connected to a means, such as a voltmeter, for measuring a so-called control voltage 17 .
  • This voltmeter is capable of measuring a voltage at their terminals. Inasmuch as the reference electrode is connected to the contact of the gate, the voltage measured by the voltmeter is a voltage V GS of the ISFET transistor across the gate and the source.
  • the current generator and the voltage generator 16 are used to generate the passage of a constant current and a constant electric voltage between the source 11 and the drain 12 .
  • the values of this voltage and of this current are stable and high enough to enable the transistor to be biased.
  • the variation in the pH of the solution to be analyzed induces the variation of its electrochemical potential which modifies the voltage V GS of the transistor.
  • the gate-source voltage V GS varies linearly according to the pH for a drain-source current I DS and a drain-source voltage V DS that are constant.
  • the voltage V GS is then measured at the terminals of the reference electrode 15 and the source 11 . The measurement of this voltage therefore enables the value of the pH of the solution to be determined
  • ISFET electrode probes are more resistant, easier to store since they can be stored in a dry state, more precise and faster because they have a very short response time.
  • ISFET electrode probes and more generally probes for measuring pH can however be further improved.
  • V GS C 2 ⁇ pH+ E 0
  • the probe In the recalibration phases, the probe is dismounted so as to be placed alternately in solutions having pH values that are known and different from one another.
  • the comparison of the pH values measured by the probe with the real values then allows to correct the value of the slope and/or the intercept point of the pH curve of the probe in such a way that the pH value measured with the probe is identical to the real value of the pH of the solution analyzed.
  • the recalibration phases dictate the stoppage of the processes in which the pH is used as a control parameter. This leads to a loss of productivity.
  • the recalibrations induce a drop in the production of treated water.
  • the invention is aimed especially at overcoming the drawbacks of the prior art.
  • reagent such as a liquid electrolyte or reagent in the form of gel
  • such a device also comprises means for modifying the value of the pH of said effluent in proximity to said means for measuring.
  • such a device in addition preferably comprises means for calibrating said device for measuring, said means for calibrating being configured to calibrate the device for measuring after modification of said pH of said effluent in proximity to said means for measuring by said means for modifying.
  • the invention relies on a wholly original approach in which means are integrated, into a pH measurement probe, to modify the pH of the effluent locally, i.e. in proximity to the active part of the probe (elements of the probe in contact with the effluent at the level at which the measurement is made).
  • the technique according to the invention thus makes it possible to carry out an in situ calibration without dismounting the pH probe and therefore facilitates the calibration, reduces the time needed for calibration and reduces its inherent cost.
  • said means for measuring comprise:
  • an ISFET type transistor comprising a source and a drain disposed on a substrate, and a gate that is to be put into contact with said effluent;
  • V GS C 2 ⁇ pH+ E 0 , where E 0 and C 2 are predefined constants;
  • said means for calibrating being preferably configured to implement phases or steps of calibration during which:
  • the invention relies in this embodiment on a wholly original approach in which there is integrated, into a probe for measuring the pH of a type comprising an ISFET transistor, means to locally modify the pH of the effluent and means to calibrate, in situ, the device for measuring.
  • the reference electrode and the gate are put into contact with it.
  • the H + ions that it contains modify the electrochemical potential of the solution and therefore the voltage V GS of the ISFET.
  • Means for generating a constant electric current and a constant voltage are then implemented to generate a constant current and a constant voltage at the terminals of the source and the drain, the values of which are chosen to enable the ISFET transistor to be biased.
  • control voltage V GS is then measured at the terminals of the source and the gate or more specifically of the reference electrode.
  • the value of this control voltage varies according to the pH of the effluent.
  • the pH of the effluent is then determined according to the value of the control voltage.
  • the means for calibrating preferably act on the means for modifying of the pH to locally carry the value of the pH of the effluent to a known value. They then command the measurement of V GS and then compute the value of E 0 which is the intercept point of the curve of the voltage V GS as a function of the pH.
  • Said means for modifying the value of the pH preferentially comprise an anode and a cathode to be put into contact with said effluent, and first means for generating electric current between said anode and said cathode.
  • the invention in this case relies on a wholly original approach which consists of the integration, into a pH-measuring probe of the type comprising an ISFET transistor, of an anode and a cathode planned to come into contact with the effluent to be analyzed, and means for generating an electric current at the terminals of this electrodes.
  • this probe does not perceive a drift between the value of pH measured by means of the probe and the real value of the pH
  • this probe is regularly calibrated in situ.
  • an electric current is applied between the anode and the cathode.
  • the production of protons is generated in the effluent in proximity to the measurement means; in the case of an ISFET, at the proximity of the active surface of the gate, by oxidation of water according to the formula H 2 O ⁇ 2O 2 +4H 30 4e ⁇ .
  • the pH of the effluent can thus be modified locally in a controlled manner.
  • the technique according to the invention therefore makes it possible to carry out the calibration of the probe, also called a recalibration, in situ, i.e. without dismounting it and without influencing the medium in which the measurement is made. Indeed, the quantity of H + ions generated is small as compared with the volume of liquid in which the measurement is made.
  • the technique of the invention therefore takes part in facilitating the calibration of a pH measuring probe of the type comprising an ISFET transistor and accordingly reducing the cost inherent in this calibration.
  • Said device for example said means for modifying the pH, preferably comprises command means to implement or not implement said first means for generating an electric current.
  • the first means of current generation will not be implemented to carry out a classic measurement of pH and then could be implemented to locally modify the pH before carrying out new measurements of pH in order to calibrate the device.
  • a device comprises a membrane permeable to the H + ions covering and being in contact with said anode and at least partly said means for measuring, in particular the active part of these means.
  • the device for measuring is of the type comprising an ISFET type transistor, and when it comprises a membrane permeable to H + ions, this membrane covers said gate and said anode, said gate and said anode being in contact with said membrane.
  • a device preferably comprises means to calibrate said device from at least one measurement of said control voltage after an implementation of said first means for generating an electric current by said command means.
  • the MOSFET transistor fulfils the function of the reference electrode, and the measured control voltage which is proportional to the pH of the solution analyzed, is the voltage at the terminals of the gates of the MOSFET and the ISFET. In this case, the MOSFET is completely encapsulated. Only the gates of the ISFET as well as the anode and the cathode can be put into contact with the effluent to be analyzed.
  • the reference electrode will be designed to be put into contact with the effluent to carry out the measurement of the pH.
  • the invention also relates to a method for measuring the pH of an effluent by means of a device according to any one of the variants described here above.
  • a step for calibrating comprising, in addition to the previous step, at least one step for modifying the value of the pH of said effluent in proximity to said means for measuring with said means for modifying the value of the of said effluent.
  • such a method preferably comprises:
  • a step for calibrating comprising at least one step for modifying said pH of said effluent in proximity to said means for measuring by said means for modifying, and a step for calibrating said device for measuring by said means for calibrating.
  • said step for measuring the pH comprises:
  • V GS C 2 ⁇ pH+E 0 , where E 0 and C 2 are predefined constants.
  • Said step for calibrating preferably comprises at least:
  • the calibration consists in modifying the value of the intercept point of the control voltage V GS expressed as a function of pH.
  • said step for calibrating comprises
  • the calibration consists in modifying the value of the intercept point E 0 and the slope C 2 of the control voltage V GS expressed as a function of the pH.
  • said step for calibrating could include a step for generating a constant electric current between said anode and said cathode.
  • Said step or steps for modifying said pH could include a step for implementing said first means for generating an electric current.
  • said step for calibrating could be implemented at a predetermined frequency, preferably daily.
  • Said step for measuring could be implemented continuously or not continuously. The measurement of the pH will naturally be stopped during the calibration except for the pH measurement needed for the calibration.
  • the frequency of implementation of the calibration could be adjustable.
  • the invention also concerns an element for measuring the pH of a device according to any one of the variants explained here above.
  • a element comprises:
  • an ISFET type transistor comprising a source and a drain disposed on a substrate, and a gate to be put into contact with said effluent;
  • FIG. 1 illustrates a probe for measuring the pH according to the prior art
  • FIG. 2 illustrates a probe for measuring the pH according to the invention
  • FIGS. 3 and 4 illustrate curves showing the evolution in time of the real value of the pH of a solution, the value of the pH measured by means of a probe according to the prior art, and the value of the pH measured by means of a probe according to the invention;
  • FIG. 5 illustrates the diagram of a part of an electric circuit of a probe according to the invention, the reference electrode of which is constituted by a MOSFET transistor.
  • the general principle of the invention consists of the integration, into a pH measuring probe, of means for modifying the pH of the effluent locally, i.e. in proximity to the active part of the probe (elements of the probe in contact with the effluent at which the measurement is made).
  • the technique according to the invention thus enables a calibration to be done in situ without dismounting the pH probe and therefore facilitates the calibration, reduces the time needed for the calibration and reduces the cost inherent in this calibration.
  • the invention consists of the integration, into a pH measuring probe of a type comprising an ISFET transistor, of an anode and a cathode to be put into contact with the effluent to be analyzed and of means for generating an electric current at the terminals of the anode and the cathode.
  • the probe To measure the pH of an effluent, the probe is put into contact with it, a constant voltage V DS is applied to the terminals of the drain and the source and a constant electric current I DS is put into circulation across these terminals in order to bias the transistor. Then, the generation of a voltage V GS is observed at the terminals of the source and the gate, the value of which is proportional to that of the pH of the effluent. This voltage is measured and then the pH of the effluent is determined as a function of the value of voltage measured.
  • an electric current is created between the anode and the cathode.
  • the production of protons is generated in proximity to the active surface of the gate in order to locally modify the pH of the effluent.
  • the technique of the invention therefore plays a part in facilitating the calibration of a pH measuring probe of a type comprising an ISFET transistor and therefore in reducing its inherent cost.
  • a device for measuring pH according to the invention also called a pH measuring probe.
  • such a probe comprises an ISFET type transistor.
  • This probe classically comprises a source 21 and a drain 22 placed on a substrate 23 .
  • the drain and the source are doped. Their doping could respectively be N type or P type doping, or vice versa, depending on the type of flow between the source and the drain.
  • It also classically comprises a gate 24 .
  • the gate 24 is separated from the source 21 and the drain 23 by an insulator 25 and comprises a surface sensitive to the H + ions.
  • the gate is made out of Ta 2 O 5 .
  • the probe also comprises a reference electrode 26 , which is connected with the gate contact of the electronic control circuitry and enables the measurement of the variations in potential at the contact of the gate 24 . It also comprises an anode 27 and a cathode 28 .
  • the anode is made of platinum and the cathode is made of stainless steel. Other suitable materials can also be used.
  • the anode 27 extends all around the gate 24 without being in contact with it.
  • the anode 27 as well as the gate 24 are coated with a membrane 29 with which they are in contact.
  • This membrane 29 is permeable to the H + ions. It is made out of polymer such as for example poly(2-hydroxyethylmethacrylate), agarose, polyvinyl alcohol (PVA), etc. It preferably takes the form of a gel. Its thickness preferably ranges from 40 to 150 microns. It is preferably fixedly attached to the anode and to the gate by covalent bonds.
  • This membrane 29 as well the reference electrode 26 and the cathode 28 are designed to be put into contact with the effluent E, the pH of which is to be measured.
  • the probe comprises means 30 for generating a voltage V DS , such as a voltage generator, and a current generator I DS , such as an electric current generator, which are connected to the terminals of the source 21 and the drain 22 through means for connecting provided for this purpose. These means enable the application of a voltage V DS of constant value and an electric current I DS of constant value between the source and the drain.
  • V DS voltage generator
  • I DS electric current generator
  • the probe comprises means for measuring a voltage V GS between the gate 24 and the source 21 such as for example a voltmeter 31 .
  • these means for measuring are connected to the source and to the reference electrode. They enable the measurement of V GS since the gate and the reference electrodes are both in contact with the effluent to be analyzed.
  • This voltage varies as a function of the pH of the solution to be analyzed.
  • the probe comprises means 32 for generating an electric current, such as an electric current generator, that are connected to the terminals of the anode 27 and the cathode 28 through means for connecting provided for this purpose.
  • an electric current generator such as an electric current generator
  • These means for generating current enable the generation of a constant electric current between the anode and the cathode. This current enables the generation of a fixed concentration of protons proportional to the pH.
  • C 1 is a constant and i is the intensity of the current imposed between the anode and the cathode.
  • the value of the constant C 1 can be determined during a first step and a second step of initial setting in the factory.
  • the first step consists in carrying out a calibration of the ISFET transistor probe with solutions having known pH values, without generating any current between the anode and the cathode.
  • different values of current are applied between the anode and the cathode and the corresponding pH is measured by means of the ISFET transistor probe.
  • a characteristic curve linking the value of the measured pH and the generated current is obtained by linear regression. It establishes the value C 1 necessary for the in situ calibration, C 1 being its slope. The constant C 1 is thus determined during the manufacture of the probe.
  • the probe comprises means for determining the value of the pH of the effluent according to the value of the voltage V GS measured at the terminals of the gate 24 and the source 21 .
  • V GS ( ⁇ 2.3 RT/nF ) ⁇ pH+ E 0
  • the initial calibration of the probe comprises a first measurement of the voltage V GS , called V GS1 , in a first solution at a first value of pH, pH 1 , and then a second value of the voltage V GS , called V GS2 , in a second solution at a second value of pH, pH 2 .
  • the values of the constants E 0 and C 2 can then be computed by applying the following formulae:
  • the command means and the means for determining the value of the pH comprise a microcontroller.
  • the probe comprises means for calibrating. These means for calibrating comprise the microcontroller which enables the pH measurement cycles and probe calibration cycles to be carried out in alternation.
  • the values of E 0 and C 2 vary over time owing to the ageing of the probe.
  • the in situ calibration is aimed at correcting the intercept point and/or the slope to make sure that the value of pH measured by means of the probe truly reflects reality.
  • the microcontroller is designed to:
  • the microcontroller is designed to:
  • this effluent is put into contact with the reference electrode 26 and with the membrane 29 (hence with the gate and the anode) and with the cathode.
  • the microcontroller drives the probe so that no current is delivered at the anode and the cathode.
  • the H + ions contained by the effluent E then spread inside the membrane 29 so that a equilibrium of concentration is obtained between the interior and the exterior of the membrane 29 , i.e. the effluent, for which the measurement is made.
  • the concentration in H + ions in the membrane 29 is therefore identical to that of the effluent E.
  • the microcontroller acts on the means for generating electric current and voltage to generate a constant voltage V DS as well as a circulation of a constant electric current I DS between the source 21 and the drain 22 .
  • the values of this electric current and this electric voltage will be chosen so that they enable the transistor to be biased.
  • This voltage is the voltage V GS of the IFSET transistor between the gate and the source.
  • the value of this voltage V GS is proportional to the value of the pH of the effluent E. This voltage varies linearly as a function of the pH for a constant current I DS and a constant voltage V DS .
  • the microcontroller records this voltage V GS .
  • the microcontroller determines the value of the pH of the effluent E according to the value of the electric voltage V GS measured at the terminals of the source 21 and the gate 24 in applying for example the formula:
  • V GS C 2 ⁇ pH+ E 0 .
  • phases of calibration or recalibration of the probe are implemented regularly, preferably daily.
  • the microcontroller acts on the means for generating current to generate a current of known intensity I 1 at the anode and the cathode for an adjustable duration T 1 varying from 1 minute to 30 minutes depending on the time needed to put the concentration in H + ions in equilibrium in the membrane.
  • This duration is parametrized in the factory.
  • This current intensity I 1 generates the production of protons for the duration T 1 and thus carries the pH in the membrane to a known value pH 1 .
  • the H + ions generated are far greater in quantity than the protons present in the effluent (in a log relationship), which makes it possible to overlook the influence of the pH of the water outside the membrane for the calibration.
  • the microcontroller acts on the means for generating current and voltage to generate a constant electric current I DS and a constant voltage V DS between the source and the drain: the transistor is then biased.
  • the microcontroller acts on the means for generating current to generate a first current of a known intensity I 1 at the anode and the cathode for an adjustable duration T 1 varying from 1 minute to 30 minutes depending on the time needed for obtaining equilibrium of concentration of H + ions in the membrane.
  • This duration is parameterized in the factory.
  • This current intensity I 1 generates the production of protons for the duration T 1 and thus takes the pH in the membrane to a known value pH 1 .
  • the microcontroller acts on the means for generating current and voltage to generate a constant electric current I DS and a constant electric voltage V DS between the source and the drain: the transistor is then biased.
  • the microcontroller then activates a measurement of the voltage V GS1 between the gate and the source, and memorizes the values of V GS1 , pH 1 and I 1 .
  • the microcontroller then again acts on the current generating means to generate a second current of a known intensity I 2 at the anode and the cathode for an adjustable duration T 2 varying from 1 minute to 30 minutes to take the pH within the membrane to a second known value pH 2 .
  • the microcontroller again acts on the means for generating current and voltage to generate a constant electric current I DS and a constant electric voltage V DS between the source and the drain in order to bias the transistor.
  • the microcontroller then activates a measurement of the voltage V GS2 between the gate and the source, and memorizes the values of V GS2 , pH 2 and I 2 .
  • the microcontroller then computes the values of the slope C 2 and of the intercept point E 0 in applying the formulae:
  • FIGS. 3 and 4 illustrate:
  • the drift between the real value of the pH and the value of the pH measured by means of a probe according to the invention is almost zero or at least appreciably smaller than the drift observed between the real value of the pH and the value of the pH measured by a prior-art probe.
  • the membrane will not be implemented.
  • the generation of the current at the anode and the cathode will modify the value of the pH of the effluent in a controlled manner in proximity to the gate.
  • the structure and the operation of the probe according to this variant are identical to those of the probe comprising the membrane.
  • the reference electrode of the probe could be replaced by a MOSFET (Metal/Oxide/Semi-conductor Field Effect Transistor) type transistor.
  • MOSFET Metal/Oxide/Semi-conductor Field Effect Transistor
  • the gate of the MOSFET is electrically connected to the gate of the ISFET and a constant current and voltage are applied between the source and the drain of the MOSFET to bias it.
  • the measurement of the voltage at the terminals of the gate of the MOSFET and that of the ISFET which is proportional to the pH of the solution to be analyzed makes it possible to deduce the pH from this.
  • the reference electrode could be constituted by a reference pseudo-electrode made of silver-silver chloride wire, gold wire or other types of wire.
  • FIG. 5 illustrates an example of an electronic connection diagram of the MOSFET and ISFET transistors of a probe according to this variant.
  • a differential cascade is implemented.
  • This cascade contains a transistor T 5 in a feedback connection.
  • the transistors T 3 and T 4 are the active load of the MOSFET and of the ISFET which ensures the equality of the drain in these two transistors.
  • the transistor T 5 (identical to T 3 and T 4 ) drives the gate voltage of the MOSFET.
  • the type of conductivity of the channel of the transistors T 3 , T 4 and T 5 is opposite that of the ISFET and the MOSFET.
  • the condition I CS2 0.5 ⁇ I CS1 is needed.
  • the potential on the source V S1 must increase since the drain-source current I DS1 and the potential at the drain V D1 are fixed by all the transistors T 3 , T 4 , T 5 .
  • the potential is measured relatively to the ground of the circuit. It corresponds to the voltage between the gates of the MOSFET and the ISFET which is proportional to the pH of the solution.

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FR1350666 2013-01-25
FR1350666A FR3001547B1 (fr) 2013-01-25 2013-01-25 Dispositif de mesure de la valeur du ph comprenant des moyens de calibrage in situ
PCT/EP2014/051454 WO2014114773A1 (fr) 2013-01-25 2014-01-24 Dispositif de mesure de la valeur du ph comprenant des moyens de calibrage in situ

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JP2017203718A (ja) * 2016-05-12 2017-11-16 横河電機株式会社 イオンセンサ、イオン濃度の測定方法、および発酵物の製造方法
GB2566463A (en) * 2017-09-13 2019-03-20 Univ Southampton pH Sensor and Calibration method
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WO2014114773A1 (fr) 2014-07-31
ZA201504966B (en) 2016-06-29
CN104937402A (zh) 2015-09-23
AU2014209850A1 (en) 2015-09-10
CN104937402B (zh) 2019-08-06
US20200011830A1 (en) 2020-01-09
FR3001547B1 (fr) 2016-05-06
EP2956764B1 (fr) 2020-08-12
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US10900929B2 (en) 2021-01-26
AU2014209850B2 (en) 2017-09-07

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