WO2019070961A1 - Capteur de ph, élément de détection de ph et composition de verre associée - Google Patents

Capteur de ph, élément de détection de ph et composition de verre associée Download PDF

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Publication number
WO2019070961A1
WO2019070961A1 PCT/US2018/054344 US2018054344W WO2019070961A1 WO 2019070961 A1 WO2019070961 A1 WO 2019070961A1 US 2018054344 W US2018054344 W US 2018054344W WO 2019070961 A1 WO2019070961 A1 WO 2019070961A1
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WIPO (PCT)
Prior art keywords
mol
chamber
sensing
fluid
sensor
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PCT/US2018/054344
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English (en)
Inventor
Alex Smith
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Sensorex Corporation
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Publication of WO2019070961A1 publication Critical patent/WO2019070961A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • C03C4/18—Compositions for glass with special properties for ion-sensitive glass
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
    • 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
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/36—Glass electrodes

Definitions

  • the present disclosure relates to pH sensors for measuring the hydrogen-ion activity in various test samples, and more particularly to pH sensors with a pH sensing chamber fabricated from a composition that results in both desirable DC conductivity and corrosion resistance.
  • a pH sensor is an example of an ion selective electrode (ISE), or measuring electrode, used during potentiometric determination of pH.
  • the pH sensor may comprise the measuring electrode reacting on a special ion type, such as a hydrogen ion, and a reference electrode that are jointly immersed in a test sample.
  • Determination of a pH measurement with a pH sensor relies on the measurement of a voltage.
  • two points with different electrical potential values i.e., electrical signals
  • the reference electrode is designed to maintain a constant electrical potential that is independent of the test sample composition and temperature.
  • the measuring electrode of the pH sensor provides an electrical potential that is dependent upon the activity of the hydrogen ions in the test sample. The difference between these potentials, the voltage, determines the pH value based on the Nernst equation.
  • a pH sensing chamber is connected to a distal end of a pH fluid chamber.
  • a sensing membrane portion of the pH sensing chamber is filled with a pH fluid of known pH, which is typically a pH of 7.
  • the pH sensing chamber design creates an environment with constant binding of hydrogen ions to the measuring electrode inside of the pH sensing chamber, while the outside of the pH sensing chamber is exposed to the test sample in which a variable amount of hydrogen ions exist. The difference in hydrogen ion activity creates a potential that is read against the potential of the reference electrode.
  • the shape of the pH sensing chamber may vary so as to ensure optimal moistening of the pH sensing chamber. Bulb-shaped and coned-shaped pH sensing chambers may be used for most applications. Some applications may require a spear-tipped pH sensing chamber, such as applications that require the penetration of a semi-solid test sample. Other applications may require a flat pH sensing chamber, such as applications that require the measurement of a solid surface, such as skin.
  • the reference electrode and the measuring electrode may be present in separate chambers or they may be combined in a single pH sensor.
  • the pH sensor may be immersed in the test sample such that the reference fluid is connected to the test sample through the fluidic reference junction, as the fluidic reference junction serves to close the electrical circuit in the pH sensor.
  • a novel glass composition having a desired range or combination of a redox buffer component and a corrosion resistance component provide the glass composition with both high DC conductivity (i.e., fast sensor response times) and excellent corrosion resistance
  • a pH sensor and methods for measuring the hydrogen-ion activity in various solutions with the pH sensor are provided.
  • a pH sensor comprising a pH sensing element, a reference sensing element, and a fluidic reference junction.
  • the pH sensing element comprises a measuring electrode, a pH fluid chamber, and a pH sensing chamber.
  • the reference sensing element comprises a reference electrode, a reference fluid chamber, and a reference fluid partition.
  • the reference fluid partition is configured to define a fluid flow barrier between an interior of the reference fluid chamber and a test sample that is characterized by an indeterminate pH.
  • the fluidic reference junction forms a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode resides in the pH sensing chamber.
  • the pH sensing chamber is fluidly coupled to the pH fluid chamber.
  • the reference electrode resides in the reference fluid chamber.
  • a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about 5.0 mol% Ta 2 0 5, an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component comprising Ce0 2 , where C > 0.0% and A>B>C.
  • a pH sensor comprising a pH sensing element, a reference sensing element, and a fluidic reference junction.
  • the pH sensing element comprises a measuring electrode, a pH fluid chamber, and a pH sensing chamber.
  • the reference sensing element comprises a reference electrode, a reference fluid chamber, and a reference fluid partition.
  • the reference fluid partition is configured to define a fluid flow barrier between an interior of the reference fluid chamber and a test sample that is characterized by an indeterminate pH.
  • the fluidic reference junction forms a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode resides in the pH sensing chamber.
  • the pH sensing chamber is fluidly coupled to the pH fluid chamber.
  • the reference electrode resides in the reference fluid chamber.
  • a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about 5.0 mol% Ta 2 Os i an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component.
  • a pH sensing element comprising a measuring electrode, a pH fluid chamber, and a pH sensing chamber.
  • the measuring electrode resides in the pH sensing chamber.
  • the pH sensing chamber is fluidly coupled to the pH fluid chamber, and a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3 , from about 0.3 mol% to about 5.0 mol% Ta 2 Os, an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component.
  • Fig. 1 is a diagram of a pH sensor, according to one or more embodiments presently described.
  • Fig. 2 is a diagram of the pH sensing chamber of the pH sensor, according to one or more embodiments presently described.
  • Fig. 3 is a graph showing the DC resistance of comparative pH sensors and pH sensors according to one or more embodiments presently described.
  • Fig. 4 is a graph showing the asymmetry potential of comparative pH sensors and pH sensors according to one or more embodiments presently described.
  • a pH sensor 10 comprising a pH sensing element 20, a reference sensing element 30, and a fluidic reference junction 40.
  • the pH sensing element 20 comprises a measuring electrode 22, a pH fluid chamber 24, and a pH sensing chamber 26.
  • the reference sensing element 30 comprises a reference electrode 32, a reference fluid chamber 34, and a reference fluid partition 36.
  • the reference fluid partition 36 is configured to define a fluid flow barrier between an interior of the reference fluid chamber 34 and a test sample that is characterized by an indeterminate pH.
  • the fluidic reference junction 40 forms a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode 22 resides in the pH sensing chamber 26.
  • the pH sensing chamber 26 is fluidly coupled to the pH fluid chamber 24.
  • the reference electrode 32 resides in the reference fluid chamber 34.
  • a sensing membrane portion 28 of the pH sensing chamber 26 is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about 5.0 mol% Ta 2 Os i an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component comprising Ce0 2 , where C > 0.0% and A>B>C.
  • the glass composition comprises from about 60.0 mol% to about 65.0 mol% Si0 2 , from about 25.0 mol% to about 30.0 mol% Li 2 0, from about 2.3 mol% to about 2.8 mol% La 2 0 3 , from about 1.5 mol% to about 1.9 mol% Ta 2 Os, an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 3.4 mol% to about 3.8 mol%, an amount B of Cs 2 0, where B is from about 1.6 mol% to about 2.0 mol%, and an amount C of a redox buffer component comprising Ce0 2 , where C is from about 0.7 mol% to about 1.1 mol%.
  • the glass composition comprises about 62.0 mol% Si0 2 , about 27.4 mol% Li 2 0, about 2.6 mol% La 2 0 3 , about 1.7 mol% Ta 2 Os, an amount A of a corrosion resistance component comprising Ti0 2 , where A is about 3.6 mol%, an amount B of Cs 2 0, where B is about 1.8 mol%, and an amount C of a redox buffer component comprising Ce0 2 , where C is about 0.9 mol%.
  • the glass composition may comprise (in mol%) greater than about 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 or 4.9 and less than about 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1,
  • the corrosion resistance component is Ti0 2 and the glass composition may comprise between about 0.3 mol% and about 5.0 mol%, about 0.4 mol% and about 4.8 mol%, about 0.6 mol% and about 4.8 mol%, about 0.8 mol% and about 4.8 mol%, about 1.0 mol% and about 4.8 mol%, about 1.2 mol% and about 4.8 mol%, about 2.9 mol% and about 4.3 mol%, about 3.0 mol% and about 4.9 mol%, about 3.1 mol% and about 4.1 mol%, about 3.2 mol% and about 4.0 mol%, about 3.3 mol% and about 3.9 mol%, about 3.4 mol% and about 3.8 mol%, or about 3.5 mol% and about 3.7 mol% of an amount A of the corrosion resistance component.
  • the glass composition may comprise (in mol%) greater than about 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0,
  • the glass may comprise between about 0.3 mol% and about 4.0 mol%, about 0.4 mol% and about 3.8 mol%, about 0.6 mol% and about 3.6 mol%, about 0.8 mol% and about 3.4 mol%, about 1.0 mol% and about 3.2 mol%, about 1.2 mol% and about 3.0 mol%, about 1.4 mol% and about 2.8 mol%, about 1.6 mol% and about 2.6 mol%, about 1.6 mol% and about 2.4 mol%, about 1.6 mol% and about 2.2 mol%, about 1.6 mol% and about 2.0 mol%, about 1.7 mol% and about 2.0 mol%, or about 1.7 mol% and about 1.9 mol% of an amount B of Cs 2 0.
  • the glass composition may comprise (in mol%) greater than about 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8,
  • the redox buffer component may be Ce0 2 , V 2 O 5 , Ru0 2 , CoO, Pr 2 0 3 , or combinations thereof so long as the total concentration of the amount C of the redox buffer component comprising the glass composition is between about 0.3 mol% and about 4.0 mol%.
  • the glass composition may comprise between about 0.3 mol% and about 4.0 mol%, about 0.4 mol% and about 3.0 mol%, about 0.5 mol% and about 2.0 mol%, about 0.5 mol% and about 1.8 mol%, about 0.5 mol% and about 1.6 mol%, about 0.5 mol% and about 1.4 mol%, about 0.5 mol% and about 1.3 mol%, about 0.5 mol% and about 1.2 mol%, about 0.5 mol% and about 1.1 mol%, about 0.5 mol% and about 1.0 mol%, or about 0.5 mol% and about 0.9 mol% of an amount C of the redox buffer component.
  • the redox buffer component is Ce0 2 and the glass composition may comprise between about 0.3 mol% and about 3.0 mol%, about 0.4 mol% and about 2.0 mol%, about 0.5 mol% and about 1.5 mol%, about 0.6 mol% and about 1.3 mol%, about 0.7 mol% and about 1.2 mol%, about 0.8 mol% and about 1.1 mol%, about 0.8 mol% and about 1.0 mol%, about 1.3 mol% and about 2.7 mol%, about 1.4 mol% and about 2.6 mol%, about 1.5 mol% and about 2.5 mol%, about 1.6 mol% and about 2.4 mol%, about 1.7 mol% and about 2.3 mol%, about 1.8 mol% and about 2.2 mol%, about 1.9 mol% and about 2.1 mol%, about 2.1 mol% and about 3.5 mol%, about 2.2 mol% and about 3.4 mol%, about 2.3 mol% and about 3.3
  • the glass composition may comprise a molar ratio of an amount A of the corrosion resistance component to an amount B of Cs 2 0 to an amount C of the redox buffer component.
  • the ratio of A to B to C may be between about 3:2: 1 to about 5:2: 1, about 3.5:2: 1 to about 5:2: 1, about 4:2: 1 to about 5:2: 1, about 4.5:2: 1 to about 5:2: 1, about 3:2: 1 to about 4.5:2: 1, about 3:2: 1 to about 4:2: 1, or about 3:2: 1 to about 3.5:2: 1.
  • the ratio of A to B to C is about 4:2: 1.
  • the glass composition is substantially free from a functional amount of alkaline earth metals.
  • alkaline earth metals encompasses elemental alkaline earth metals or any compounds comprising an amount of alkaline earth metals. Such materials are undesirable during the manufacturing process of the glass composition due to their high toxicity. Moreover, alkaline earth metals may also result in the need for increased temperatures during the manufacturing process of the glass composition.
  • the glass composition is substantially free from a functional amount of actinides.
  • actinides encompasses elemental actinides or any compounds comprising an amount of actinides. Such materials are undesirable during the manufacturing process of the glass composition due to their high toxicity stemming from radioactivity. As such, actinides are an undesirable component of the glass composition.
  • the glass composition is substantially free from a functional amount Fe 2 0 3 .
  • Fe 2 0 3 has typically been used as a redox buffer component in glass compositions.
  • Fe 2 0 3 does not produce a desirable asymmetry stabilizing effect. As such Fe 2 0 3 is an undesirable component of the glass composition.
  • the redox buffer component provides a redox couple active within the glass composition of the sensing membrane portion 28 and serves as a redox buffer to stabilize the asymmetry potential against polarization.
  • the redox buffer component re-equilibrates and neutralizes the polarization.
  • optical basicity when an amount C of Ce0 2 is the redox buffer component, Ce 3+ exists in equilibrium with Ce 4+ within the sensing membrane portion 28 and the equilibrium ratio of Ce 3+ to Ce 4+ is determined by the glass composition of the sensing membrane portion 28 via a relationship known as "optical basicity.”
  • the local optical basicity can be affected by, for example, alkali leaching or glass etching, and thus the optical basicity can be affected by aging and corrosion of the sensing membrane portion 28.
  • the pH sensing element 20 may be formed from a monolithic piece of glass comprising the glass composition according to any of the previously described embodiments.
  • the pH sensing element 20 may be formed from two or more connected pieces of glass, such as pieces of glass that have been fused together.
  • the sensing membrane portion 28 may comprise the glass composition according to any of the previously described embodiments while the rest of the pH sensing element 20 comprises a different composition.
  • Suitable compositions of the pH sensing element 20 may include glass, plastic, or combinations thereof.
  • the pH sensing element 20 may comprise any suitable shape depending on the characteristics of a test sample to be measured. Suitable shapes of the pH sensing chamber 26 may include bulb-shaped, cone-shaped, cylindrical, spear-shaped, or flat. In preferred embodiments, the pH sensing chamber 26 is bulb-shaped.
  • the measuring electrode 22 that resides in the pH sensing chamber 26 may comprise any suitable materials. Suitable materials of the measuring electrode 22 may include an Ag/AgCl composition, an Hg/Hg 2 Cl 2 composition, or an iodine/iodide composition.
  • the pH fluid chamber 24 may comprise any suitable shape. Without being bound by theory, the pH fluid chamber 24 may be cylindrical, cubical, or have a discontinuous shape.
  • the pH sensing chamber 26 has an outer diameter from between about 2.6 mm and about 9.5 mm, about 2.8 mm and about 9.3 mm, about 3.0 mm and about 9.1 mm, about 3.2 mm and about 9.0 mm, about 3.4 mm and about 8.8 mm, about 3.6 mm and about 8.6 mm, about 3.8 mm and about 8.5 mm, about 4.0 mm and about 8.5 mm, about 4.2 mm and about 8.4 mm, about 4.4 mm and about 8.3 mm, about 4.6 mm and about 8.2 mm, about 4.8 mm and about 8.1 mm, about 5.0 mm and about 8.0 mm, about 5.2 mm and about 7.9 mm, about 5.4 mm and about 7.8 mm, about 5.6 mm and about 7.7 mm, about 5.8 mm and about 7.6 mm, about 6.0 mm and about 7.5 mm, about 6.2 mm and about 7.4 mm, about 6.4 mm and about
  • the pH sensing chamber 26 has an outer diameter of about 7.0 mm. [0043] In further embodiments, the pH sensing chamber 26 has a surface area from between about 5 mm 2 to about 145 mm 2 , about 25 mm 2 to about 140 mm 2 , about 50 mm 2 to about 135 mm 2 , about 75 mm 2 to about 130 mm 2 , about 80 mm 2 to about 130 mm 2 , about 85 mm 2 to about
  • the pH sensing chamber 26 has a surface area of about 127 mm .
  • the pH sensing chamber 26 is comprised of the glass composition according to any of the previously described embodiments and has a thickness from between about 0.12 mm and about 0.36 mm, about 0.14 mm and about 0.34 mm, about 0.16 mm and about 0.32 mm, about 0.18 mm and about 0.30 mm, about 0.20 mm and about 0.28 mm, or about 0.22 mm and about 0.26 mm. In certain embodiments, the pH sensing chamber 26 has a thickness of about 0.24 mm.
  • the reference sensing element 30 may be formed from any suitable material. Suitable materials may comprise plastic, glass, or combinations thereof. In preferred embodiments, the reference sensing element 30 comprises polyetherimide.
  • the reference sensing element 30 has an outer diameter from between about 8.0 mm and about 16.0 mm, about 8.2 mm and about 15.8 mm, about 8.4 mm and about 15.6 mm, about 8.6 mm and about 15.4 mm, about 8.8 mm and about 15.2 mm, about 9.0 mm and about 15.0 mm, about 9.2 mm and about 14.8 mm, about 9.4 mm and about 14.6 mm, about 9.6 mm and about 14.4 mm, about 9.8 mm and about 14.2 mm, about 10.0 mm and about 14.0 mm, about 10.2 mm and about 13.8 mm, about 10.4 mm and about 13.6 mm, about 10.6 mm and about 13.4 mm, about 10.8 mm and about 13.2 mm, about 11.0 mm and about 13.0 mm, about 11.2 mm and about 12.8 mm, about 11.4 mm and about 12.6 mm, about 11.6 mm and about 12.4 mm, or about 11.8 mm and
  • the reference sensing element 30 has an inner diameter from between about 6.0 mm and about 12.0 mm, about 6.2 mm and about 11.8 mm, about 6.4 mm and about 11.6 mm, about 6.6 mm and about 11.4 mm, about 6.8 mm and about 11.2 mm, about 7.0 mm and about 11.0 mm, about 7.2 mm and about 10.8 mm, about 7.4 mm and about 10.6 mm, about 7.6 mm and about 10.4 mm, about 7.8 mm and about 10.2 mm, about 8.0 mm and about 10.0 mm, about 8.2 mm and about 9.8 mm, about 8.4 mm and about 9.6 mm, about 8.6 mm and about 9.4 mm, or about 8.8 mm and about 9.2 mm.
  • the reference sensing element 30 has an outer diameter of about 8.9 mm.
  • the reference electrode 32 that resides in the reference fluid chamber 34 may comprise any suitable materials.
  • Suitable materials of the measuring electrode 22 may include an Ag/AgCl composition, an Hg/Hg 2 Cl 2 composition, or an iodine/iodide composition.
  • the reference fluid chamber 34 may comprise any suitable shape. Without being bound by theory, the reference fluid chamber 34 may be cylindrical, cubical, or have a discontinuous shape.
  • the reference fluid partition 36 is configured to define a fluid flow barrier between an interior of the reference fluid chamber 34 and a test sample that is characterized by an indeterminate pH.
  • a test sample having an "indeterminate" pH refers to any sample where the pH of the sample is either unknown or needs to be measured, tested, or otherwise validated.
  • the test sample may be a solution, fluid, liquid, or any other fluid, fluidic solid, or solid that is compatible with the pH sensor described herein.
  • the reference fluid partition 36 is a silicone bushing.
  • the pH sensor 20 may further comprise an intermediate reference fluid partition 38 defining a separate fluid flow barrier within the reference fluid chamber 34.
  • the intermediate reference fluid partition 38 is configured to define a fluid flow barrier between an interior of the reference fluid chamber 34 and a test sample that is characterized by an indeterminate pH.
  • the intermediate reference fluid partition 38 is a silicone bushing.
  • the fluidic reference junction 40 forms a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode 22 resides in the pH sensing chamber 26.
  • the fluidic reference junction 40 is characterized by a reference fluid flow rate from between about 0 mL/day to about 2.0 mL/day, about 0.1 mL/day to about 1.9 mL/day, about 0.2 mL/day to about 1.8 mL/day, about 0.3 mL/day to about 1.7 mL/day, about 0.4 mL/day to about 1.4 mL/day, about 0.5 mL/day to about 1.5 mL/day, about 0.6 mL/day to about 1.4 mL/day, about 0.7 mL/day to about 1.3 mL/day, about 0.8 mL/day to about 1.2 mL/day, or about 0.9 mL/day to about 1.1 mL/day.
  • a reference fluid flow rate from between about 0 mL/day to about
  • the reference fluid junction 40 comprises a fluid via formed in the reference fluid partition.
  • the fluid via may comprise an annular gap, a cylindrical via, or any other opening suitable to form a reference fluid diffusion path across the reference fluid partition.
  • the reference fluid junction 40 comprises a fluid permeable material extending across the reference fluid partition.
  • the fluid permeable material may comprise a ceramic, a glass ceramic, a metal, or any of a variety of fibrous or non-fibrous fluid permeable materials.
  • suitable materials include Pellon ®, ceramic, platinum, glass, ground glass, or plastic fibers.
  • the pH sensor 10, in certain embodiments, may further comprise an intermediate reference fluid junction 42.
  • the intermediate reference fluid junction 42 may be described according to any of the preciously described embodiments of the reference fluid junction 40.
  • the pH sensor 10 further comprises a pH fluid residing in the pH fluid chamber 24.
  • the pH fluid may comprise any fluid capable of creating a suitable diffusion potential. Examples of suitable pH fluids may include, but are not limited to, metal halide salts such as KC1.
  • the pH fluid may have a pH from about 1 to about 13 and a concentration from about 0.001 M to about 10 M.
  • the pH fluid residing in the pH fluid chamber 24 has a viscosity from between 0.35 cP and 180 cP.
  • the pH fluid is a KC1 gel having a pH of about 7.
  • the reference fluid chamber 34 further comprises a reference fluid residing in the reference fluid chamber 34.
  • the reference fluid may comprise any fluid capable of creating a suitable diffusion potential. Examples of suitable reference fluids may include, but are not limited to, metal halide salts such as KC1.
  • the reference fluid in embodiments, may have a pH from about 6 to about 9 and a concentration from about 0.001 M to about 5 M.
  • the reference fluid residing in the reference fluid chamber 34 has a viscosity from between 0.35 cP and 180 cP.
  • the reference fluid in embodiments, may be the same fluid that comprises the pH fluid.
  • the components of the pH sensing element 10 may be arranged coaxially, meaning that the pH sensing element 20 resides within the reference sensing element 30.
  • the pH sensing element 20 and its components, and the reference sensing element 30 and its components are separated into multiple electrodes.
  • the reference sensing element 30 may further comprise a sensor extension portion surrounding at least a portion of the pH sensing chamber 26.
  • the sensor extension portion and the pH sensing chamber 26 define a minimum displacement buffer gap between the sensor extension portion of the reference sensing element 30 and the pH sensing chamber 26.
  • the minimum displacement buffer gap is between about 0.8 mm and about 2 mm. The minimum displacement buffer gap helps shield the pH sensing chamber 26 from any disturbances, such as shock from being dropped or jostled.
  • a pH sensor 10 comprising a pH sensing element 20, a reference sensing element 30, and a fluidic reference junction 40.
  • the pH sensing element 20 comprises a measuring electrode 22, a pH fluid chamber 24, and a pH sensing chamber 26.
  • the reference sensing element 30 comprises a reference electrode 32, a reference fluid chamber 34, and a reference fluid partition 36.
  • the reference fluid partition 36 is configured to define a fluid flow barrier between an interior of the reference fluid chamber 34 and a test sample that is characterized by an indeterminate pH.
  • the fluidic reference junction 40 forms a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode 22 resides in the pH sensing chamber 26.
  • the pH sensing chamber 26 is fluidly coupled to the pH fluid chamber 24.
  • the reference electrode 32 resides in the reference fluid chamber 34.
  • a sensing membrane portion 28 of the pH sensing chamber 26 is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about 5.0 mol% Ta 2 Os , an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component.
  • a pH sensing element 20 comprising a measuring electrode 22, a pH fluid chamber 24, and a pH sensing chamber 26.
  • the measuring electrode 22 resides in the pH sensing chamber 26.
  • the pH sensing chamber 26 is fluidly coupled to the pH fluid chamber 24, and a sensing membrane portion 28 of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3 , from about 0.3 mol% to about 5.0 mol% Ta 2 Os, an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component.
  • Example 1 a pH sensor comprising a pH sensing chamber 26 fabricated from glass having a composition of 62.0 mol% Si0 2 , 27.4 mol% Li 2 0, 2.6 mol% La 2 0 3 , 1.8 mol% Cs 2 0, 0.9 mol% Ce0 2 , 1.7 mol% Ta 2 Os, and 3.6 mol% Ti0 2 was tested for DC resistance and corrosion testing.
  • Example 2 a pH sensor comprising a pH sensing chamber 26 fabricated from glass having a composition of 63.0 mol% Si0 2 , 27.8 mol% Li 2 0, 3.5 mol% La 2 0 3 , 2.9 mol% Cs 2 0, 1.6 mol% Ce0 2 , and 1.2 mol% Ta 2 Os was tested for DC resistance and corrosion testing.
  • Comparative Example 1 a current state-of-the-art pH sensor comprising a pH sensing chamber fabricated from glass having a composition of 65.0 mol% Si0 2 , 28.0 mol% Li 2 0, 4.0 mol% La 2 0 3 , and 3.0 mol% Cs 2 0 was subjected to the same DC resistance and corrosion testing as Examples 1 and 2 for comparison purposes.
  • a current state-of-the-art pH sensor comprising a pH sensing chamber fabricated from glass having a composition of 64.49 mol% Si0 2 , 27.93 mol% Li 2 0, 3.69 mol% La 2 0 3 , 2.74 mol% Cs 2 0, 0.251 mol% P 2 0 5 , 0.63 mol% Ta 2 0 5 , 0.029 mol% CoO, and 0.24 mol% Pr 2 0 3 was subjected to the same DC resistance and corrosion testing as Examples 1 and 2 for comparison purposes.
  • DC resistance for the pH sensors 10 of Examples 1 and 2, and Comparative Examples 1 and 2 were measured after hourly exposures to a corrosive solution of pressurized steam and condensed water vapor at a temperature of 125 °C and a pressure of 20 psig.
  • the DC resistance of Comparative Examples 1 and 2 increased to about 800 megaohms ( ⁇ ) after exposure to the corrosive solution. After 2 hours of exposure to the corrosive solution, the DC resistance of Comparative Example 2 increased to about 1200 ⁇ and the DC resistance of Comparative Example 1 increased slightly to about 900 ⁇ . For exposure times between 3 and 5 hours in the corrosive solution, the Comparative Examples 1 and 2 maintained a DC resistance between about 1000-1200 ⁇ .
  • the pH sensors 10 of Examples 1 and 2 maintained a low DC resistance even after 5 hours of exposure to the corrosive solution.
  • the glass probe pH sensor 10 of Example 1 increased only to about 400 ⁇ after 5 hours of exposure to the corrosive solution, whereas the pH sensor 10 of Example 2 exhibited a slight increase of DC resistance and showed about 600 ⁇ of resistance after 5 hours of exposure to the corrosive solution.
  • Fig. 3 demonstrates the pH sensors 10 of Examples 1 and 2 have superior DC conductivity (i.e., a reduced DC resistance) compared to current state of the art glass probes and the combination of the redox buffer component (here, 0.9 mol % Ce0 2 ) and the corrosion resistance component (here, 3.6 mol % Ti0 2 ) provides an increase in DC conductivity (i.e., a reduced DC resistance) compared to the addition of the redox buffer component alone.
  • the redox buffer component here, 0.9 mol % Ce0 2
  • the corrosion resistance component here, 3.6 mol % Ti0 2
  • the asymmetry potential for the pH sensors 10 of Examples 1 and 2 and Comparative Examples 1 and 2 were measured after hourly exposures of the glass probes to the same corrosive solution used for the DC resistance testing discussed above.
  • the asymmetry potential is a measure of a pH sensor's deviation from a pH of 7 when the pH sensor 10 is immersed and tested in a pH 7 buffer solution.
  • the asymmetry potential represents an offset of the glass probe from a pH of 7 when immersed and tested in neutral pH solution.
  • the pH sensors of Comparative Examples 1 and 2 exhibited a large asymmetry potential (i.e., a large offset from a pH of 7) with an offset from the pH of 7 from about 0.15 to about 0.3 pH units.
  • the pH sensors of Examples 1 and 2 showed a relatively small deviation of less than about 0.07 pH units from a pH of 7 even after 6 hours of exposure to the corrosive solution.
  • Such a small deviation in pH accuracy results in the pH sensor maintaining fidelity to the calibration standard after exposure to corrosive conditions, including the combination of pressurized steam and condensed water vapor at a temperature of 125 °C and a pressure of 20 psig.
  • this level of pH sensor performance reliability indicates that the experimental pH sensors have applications in food and beverage industries, and also pharmaceutical manufacturing processes, such as industrial fermenting.
  • a characteristic of the subject matter of the present disclosure being a "function of a parameter, variable, or other characteristic is not intended to denote that the characteristic is exclusively a function of the listed parameter, variable, or characteristic. Rather, reference herein to a characteristic that is a "function" of a listed parameter, variable, etc., is intended to be open ended such that the characteristic may be a function of a single parameter, variable, etc., or a plurality of parameters, variables, etc.
  • a pH sensor may comprise a pH sensing element comprising a measuring electrode, a pH fluid chamber, and a pH sensing chamber; a reference sensing element comprising a reference electrode, a reference fluid chamber, and a reference fluid partition configured to define a fluid flow barrier between an interior of the reference fluid chamber and a test sample characterized by an indeterminate pH, and a fluidic reference junction forming a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode resides in the pH sensing chamber; the pH sensing chamber is fluidly coupled to the pH fluid chamber; the reference electrode resides in the reference fluid chamber; and a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about
  • a second aspect of the present disclosure may include the first aspect, wherein the glass composition comprises a molar of A:B:C from about 3:2: 1 to about 5:2: 1.
  • a third aspect of the present disclosure may include the first or second aspects, wherein the glass composition is substantially free of a functional amount of alkaline earth metals, actinides, and Fe 2 0 3 .
  • a fourth aspect of the present disclosure may include any of the first through third aspects, wherein the pH sensing chamber is bulb-shaped.
  • a fifth aspect of the present disclosure may include any of the first through fourth aspects, wherein the pH sensing element resides within the reference sensing element.
  • a sixth aspect of the present disclosure may include any of the first through fifth aspects, wherein the pH sensing chamber further comprises a sensor extension portion surrounding at least a portion of the pH sensing chamber; and the sensor extension portion and the pH sensing chamber define a minimum displacement buffer gap between the sensor extension portion and the pH sensing chamber.
  • a seventh aspect of the present disclosure may include any of the first through sixth aspects, wherein the minimum displacement buffer gap is between about 0.8 mm and about 2.0 mm.
  • An eighth aspect of the present disclosure may include any of the first through seventh aspects, wherein the outer diameter of the pH sensing chamber is between about 2.6 mm and about 9.5 mm.
  • a ninth aspect of the present disclosure may include any of the first through eighth aspects, wherein the fluidic reference junction is characterized by a reference fluid flow rate from between about 0 mL/day to about 2 mL/day.
  • a tenth aspect of the present disclosure may include any of the first through ninth aspects, wherein the pH sensor further comprises an intermediate reference fluid partition defining a fluid flow barrier within the reference fluid chamber; and an intermediate reference fluid junction.
  • An eleventh aspect of the present disclosure may include any of the first through tenth aspects, wherein the fluidic reference junction and the intermediate reference fluid junction are characterized by the same flow rate.
  • An twelfth aspect of the present disclosure may include any of the first through eleventh aspects, wherein the pH sensor further comprises a pH fluid residing in the pH fluid chamber.
  • a thirteenth aspect of the present disclosure may include any of the first through twelfth aspects, wherein the pH sensor further comprises a reference fluid residing in the reference fluid chamber.
  • a pH sensor may comprise a pH sensing element comprising a measuring electrode, a pH fluid chamber, and a pH sensing chamber; a reference sensing element comprising a reference electrode, a reference fluid chamber, and a reference fluid partition configured to define a fluid flow barrier between an interior of the reference fluid chamber and a test sample characterized by an indeterminate pH; and at least one fluidic reference junction forming a reference fluid diffusion path across the reference fluid partition, wherein the measuring electrode resides in the pH sensing chamber; the pH sensing chamber is fluidly coupled to the pH fluid chamber; the reference electrode resides in the reference fluid chamber; and a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to
  • a pH sensing element may comprise a measuring electrode, a pH fluid chamber, and a pH sensing chamber, wherein the measuring electrode resides in the pH sensing chamber; the pH sensing chamber is fluidly coupled to the pH fluid chamber; and a sensing membrane portion of the pH sensing chamber is fabricated from a glass composition comprising from about 59.0 mol% to about 72.0 mol% Si0 2 , from about 20.0 mol% to about 32.0 mol% Li 2 0, from about 0.3 mol% to about 4.0 mol% La 2 0 3i from about 0.3 mol% to about 5.0 mol% Ta 2 Os , an amount A of a corrosion resistance component comprising Ti0 2 , where A is from about 0.3 mol% to about 5.0 mol%, an amount B of Cs 2 0, where B > 0.0 mol%, and an amount C of a redox buffer component.

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Abstract

Le capteur de pH illustré comprend un élément de détection de pH, un élément de détection de référence et une jonction de référence fluidique. L'élément de détection de pH comprend une électrode de mesure, une chambre de fluide de pH et une chambre de détection de pH. L'élément de détection de référence comprend une électrode de référence, une chambre de fluide de référence et une cloison de fluide de référence. La cloison de fluide de référence sert à réaliser une barrière d'écoulement de fluide entre un intérieur de la chambre de fluide de référence et un échantillon de test qui est caractérisé par un pH indéterminé. La jonction de référence fluidique forme un trajet de diffusion de fluide de référence traversant la cloison de fluide de référence, l'électrode de mesure résidant dans la chambre de détection de pH. La chambre de détection de pH est en communication fluidique avec la chambre de fluide de pH. L'électrode de référence est logée dans la chambre de fluide de référence. Une partie de membrane de détection de la chambre de détection de pH est fabriquée à partir de compositions de verre selon les modes de réalisation décrits ici.
PCT/US2018/054344 2017-10-04 2018-10-04 Capteur de ph, élément de détection de ph et composition de verre associée WO2019070961A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2668143A (en) * 1950-01-19 1954-02-02 Beckman Instruments Inc Glass electrode
SU1121247A1 (ru) * 1983-03-30 1984-10-30 Всесоюзный Ордена Трудового Красного Знамени Научно-Исследовательский Проектно-Конструкторский И Технологический Институт Источников Тока Электродное стекло
WO2003046539A2 (fr) * 2001-11-21 2003-06-05 Invensys Systems, Inc. Membrane en verre pour le ph et capteur de ph

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2668143A (en) * 1950-01-19 1954-02-02 Beckman Instruments Inc Glass electrode
SU1121247A1 (ru) * 1983-03-30 1984-10-30 Всесоюзный Ордена Трудового Красного Знамени Научно-Исследовательский Проектно-Конструкторский И Технологический Институт Источников Тока Электродное стекло
WO2003046539A2 (fr) * 2001-11-21 2003-06-05 Invensys Systems, Inc. Membrane en verre pour le ph et capteur de ph

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