Potentiostatic circuits for electrochemical sensors

Patent metadata

Field	Value
Publication number	US-9689827-B2
Application number	US-201314049426-A
Country	US
Kind code	B2
Filing date	Oct 9, 2013
Priority date	Oct 9, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

An electrochemical detector can be powered partly, or entirely by voltages generated by the sensor. Using either active circuits or a passive component which produces a predetermined voltage drop in the respective sensor, two electrode consumable anode oxygen sensors can be provided which do not evolve hydrogen during operation.

First claim

The invention claimed is:

1. A method of controlling an electrochemical sensor comprising:
operating the sensor and generating a sensor voltage wherein one of a substantially fixed load resistance or an electronically variable load resistance is coupled to the sensor;
adjusting the resistance so as to maintain a selected sensor voltage, wherein electrical energy from the sensor is coupled to the fixed load resistance or the variable load resistance;
varying the sensor voltage to reduce electrode activity; and
obtaining diagnostic information for at least one electrode in response to varying the sensor voltage.

2. A method as in claim 1 which includes providing a feedback element with an output signal, coupling the output signal to the load resistance, and, adjusting the resistance using the output signal.

3. A method as in claim 1 which includes maintaining the selected voltage between first and second electrodes of the sensor.

4. A method as in claim 1 , wherein the sensor comprises an oxygen sensor comprising two electrodes, and wherein obtaining the diagnostic information comprises obtaining diagnostic information for the two electrodes.

5. A method as in claim 1 , wherein the sensor comprises a plurality of electrodes, and wherein obtaining the diagnostic information comprises obtaining diagnostic information for the plurality of electrodes.

6. An apparatus comprising:
an electrochemical sensor, carried in a housing with two terminals carried on the housing coupled to respective sensor electrodes, and sensor output voltage establishing circuitry carried in the housing, coupled to and only powered by the sensor.

7. An apparatus as in claim 6 , where circuitry comprises an electronically variable load resistance coupled to the sensor to maintain a selected sensor voltage.

8. An apparatus as in claim 6 which includes an electrical load, releasably coupled to the sensor, wherein a voltage across the load is indicative of a gas concentration at the sensor.

9. The apparatus as in claim 6 , where the sensor output voltage establishing circuitry comprises an electronic component comprising a diode to produce a voltage drop across the sensor, where the voltage drop is sufficient to prevent hydrogen evolution without causing loss of activity over a normal operating current range of the sensor.

10. The apparatus as in claim 6 , wherein the electrochemical sensor comprises a two electrode consumable anode oxygen sensor.

11. The apparatus as in claim 6 , wherein the electrochemical sensor includes at least first and second electrodes, wherein the sensor output voltage establishing circuitry is configured to maintain a selected voltage between the at least first and second electrodes.

12. An electrochemical detector comprising:
an electrochemical sensor, wherein the electrochemical sensor comprises an oxygen sensor;
at least one of an active voltage control circuit comprising a closed loop control system Which includes an electronically variable load resistance coupled to the sensor to maintain a selected sensor voltage, or, an electronic component comprising a diode to produce a voltage drop across the sensor, where the voltage drop is sufficient to prevent hydrogen evolution without causing loss of activity over a normal operating current range of the sensor, and wherein power is obtained, at least in part, from the sensor; and
a first housing which carries at least the electrochemical sensor and a second housing which releasably receives the first housing, wherein the electrochemical sensor is coupled to an impedance element.

13. A detector as in claim 12 wherein the sensor comprises a two electrode consumable anode oxygen sensor.

14. A detector as in claim 13 where the consumable anode is selected from a class that includes at least one of a zinc or tin consumable anode.

15. A detector as in claim 14 where the sensor includes at least first and second electrodes and where the selected voltage is maintained therebetween.

16. A detector as in claim 12 where the first housing carries at least two contacts on an external surface of the housing and wherein the contacts electrically engage the impedance element when the first housing is positioned in the second housing.

17. A detector as in claim 16 where the contacts releasably engage the conductors coupled to the impedance element.

18. A detector as in claim 17 where the sensor comprises an oxygen sensor.

Assignees

• Honeywell Int Inc

Inventors

• Pratt Keith Francis Edwin
• Willett Martin
• Xiao Lei
• Hosseinmardi Ali

Classifications

• G01N27/404 Primary

  Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid {, e.g. Clark-type oxygen sensors} · CPC title

• G01N27/28 Primary

  Electrolytic cell components · CPC title

• G01N27/49

  Systems involving the determination of the current at a single specific value, or small range of values, of applied voltage for producing selective measurement of one or more particular ionic species · CPC title