US 11,460,432 B1Granted

Extended life electrode measurement method and apparatus

AssigneeHalogen Systems, Inc.

InventorsMichael A. Silveri, Adam Moore

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Abstract

A method and apparatus extend the measurement life of a working electrode in a three-electrode amperometric sensor by applying an activation sequence of voltages and a measurement sequence of voltages to the input of a potentiostat. The activation sequence includes multiple cycles wherein each cycle includes a low (more negative) voltage and a high (more positive) voltage (e.g., 0 volts) with reference to a signal ground reference. In one mode, the measurement sequence includes multiple cycles of three voltage pulses, wherein each cycle includes a measurement voltage pulse followed by a high (more positive) pulse, followed by a low (more negative) pulse. The cycles are repeated N times. In a second mode, the measurement sequence comprises a fixed measurement voltage having selectable duration.

Claims14

Dependent claims

A method for extending the measurement life of a working electrode in a three-electrode amperometric sensor for online measurement of a water parameter, the amperometric sensor including a potentiostat with selectable voltages, wherein the working electrode is a bare electrode, the method comprising:

selectively switching between a first mode and a second mode, each mode including an activation step followed by a measurement step, wherein:
the activation step comprises applying a first set of voltages to the working electrode, the first set of voltages comprising a plurality of cycles that switch from a more negative voltage in a range of −1 volt to −2.5 volts to a more positive voltage in a range of −0.2 volt to +0.5 volt, the plurality of cycles ranging from 10 cycles to 100 cycles;
and
in the first mode, the measurement step comprises:
applying a pulsed amperometric detection (PAD) sequence of three voltages to measure a current corresponding to a level of a water parameter, the sequence of three voltages comprising:
a first voltage in a range of −0.1 volt to +0.3 volt having a duration in a range of approximately 300 milliseconds to approximately 500 milliseconds;
a second voltage in a range of 0.65 volt to 0.95 volt having a duration in a range of 20 milliseconds to 300 milliseconds;
and
a third voltage in a range of −1.0 volt to −2.5 volts having a duration in a range of 20 to 300 milliseconds;
measuring a sensor current through the sensor while the first voltage in the sequence of three voltages is applied;
repeating the sequence of three voltages for at least 10 times and averaging the sensor currents to derive a current for parameter calculation;
and
in the second mode, the measurement step comprises:
switching from the PAD sequence of three voltages to a fixed measurement potential to measure the current when the measured current is below a selected signal current value, wherein the fixed measurement potential has a range from −0.05 volt to 0.5 volt and has a duration in a range from 3 seconds to 60 seconds.

11 more elements

An apparatus for measuring a water parameter, the apparatus comprising:

a three-electrode potentiostat comprising:
a measurement cell having a working electrode, a reference electrode and a counter electrode;
and
circuitry responsive to an input voltage to generate a current through the measurement cell to cause a voltage between the working electrode and the reference electrode responsive to the input voltage;
a waveform generator having an output coupled to the potentiostat, the waveform generator generating the input voltage, the waveform generator operating in at least a first mode and a second mode, wherein:
in the first mode:
the waveform generator generates the input voltage as an activation sequence followed by a first measurement sequence, wherein:
the input voltage in the activation sequence comprises a first set of voltages in a plurality of cycles that switch from a more negative voltage in a range of −1 volt to −2.5 volts to a more positive voltage in a range of −0.2 volt to +0.5 volt, the plurality of cycles ranging from 10 cycles to 100 cycles;
and
the input voltage in the measurement sequence comprises a repeated sequence of three voltages comprising:
a first voltage in a range of −0.1 volt to +0.3 volt having a duration in a range of approximately 300 milliseconds to approximately 500 milliseconds;
a second voltage in a range of 0.65 volt to 0.95 volt having a duration in a range of 20 milliseconds to 300 milliseconds;
and
a third voltage in a range of −1.0 volt to −2.5 volts having a duration in a range of 20 to 300 milliseconds;
in the second mode, the waveform generator generates the input voltage as the activation sequence followed by a second measurement sequence, wherein the second measurement sequence comprises a fixed measurement voltage, the fixed measurement voltage having a range from −0.05 volt to 0.5 volt and having a duration in a range from 3 seconds to 60 seconds;
and
a current sensor to sense the current flowing through the measurement cell as a measured current.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/014,632Filed 8 Sep 2020
Granted: 4 Oct 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01N 27/403
By investigating electrochemical variables; by using electrolysis or electrophoresis: cells and electrode assemblies
G01N 27/48
Systems: using polarography, i.e. measuring changes in current under a slowly-varying voltage
G01N 27/3273
Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood: devices therefor, e.g. test element readers, circuitry
G01N 27/4161
Systems: measuring the voltage and using a constant current supply, e.g. chronopotentiometry