Process for minimizing cross-talk in diagnostic signals of a pH sensor
First Claim
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1. A process of operating a pH analyzer to measure pH of a solution, comprising steps of:
- a) providing a pH sensor having an ion-specific electrode and a reference electrode, the ion-specific electrode being in contact with the solution and designed to provide an electrical potential based on the pH of the solution, the reference electrode being designed to provide a reference electrical potential and being coupled to the ion-specific electrode through the solution;
b) applying the pH sensor and a common electrode to the solution;
c) measuring the pH of the solution during a first cycle of operation by c1) applying a first current, IGLASS, to the ion-specific electrode during a first time period, c2) applying a second current, IREF, to the reference electrode during a second time period that is mutually exclusive of the first time period, c3) measuring a voltage, VGLASS, between the ion-specific electrode and the common electrode, c4) measuring a voltage, VREF, between the reference electrode and the common electrode, c5) identifying the pH of the solution based on a difference between the measured voltages VGLASS and VREF.
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Abstract
A pH analyzer is operated to measure pH of a solution by applying a reference electrode current, IREF, to a reference electrode of a pH sensor and an ion-specific electrode current, IGLASS, to an ion-specific electrode of the pH sensor. The currents to the reference electrode and ion-specific electrode are multiplexed to avoid cross-talk. Multiplexing the currents provides a more accurate measurement of electrode impedance for diagnostic purpose. A current spike is optionally added to the reference electrode current to discharge any charge in the solution due to the reference electrode current.
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Citations
20 Claims
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1. A process of operating a pH analyzer to measure pH of a solution, comprising steps of:
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a) providing a pH sensor having an ion-specific electrode and a reference electrode, the ion-specific electrode being in contact with the solution and designed to provide an electrical potential based on the pH of the solution, the reference electrode being designed to provide a reference electrical potential and being coupled to the ion-specific electrode through the solution;
b) applying the pH sensor and a common electrode to the solution;
c) measuring the pH of the solution during a first cycle of operation by c1) applying a first current, IGLASS, to the ion-specific electrode during a first time period, c2) applying a second current, IREF, to the reference electrode during a second time period that is mutually exclusive of the first time period, c3) measuring a voltage, VGLASS, between the ion-specific electrode and the common electrode, c4) measuring a voltage, VREF, between the reference electrode and the common electrode, c5) identifying the pH of the solution based on a difference between the measured voltages VGLASS and VREF. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process of minimizing cross-talk between a sensing electrode and a reference electrode of a sensor during a measurement of a process variable, the sensing electrode being in association with the process variable and designed to provide an electrical potential based on the process variable and the reference electrode being designed to provide a reference electrical potential and being coupled to the sensing electrode through the process variable, the sensor further having a common electrode in association with the process variable, the process comprising steps of
a) applying a first current, IGLASS, to the sensing electrode during a first time period; -
b) applying a second current, IREF, to the reference electrode during a second time period, the first and second time periods being mutually exclusive, c) measuring a voltage, VGLASS, between the sensing electrode and the common electrode, d) measuring a voltage, VREF, between the reference electrode and the common electrode, and e) identifying the measurement of the process variable from the measured voltages. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification