ELECTROCHEMICAL SENSOR

• US 20110048969A1
• Filed: 08/06/2010
• Published: 03/03/2011
• Est. Priority Date: 01/08/2004
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Lawrence, Nathan, Lafitte, Valerie
• Granted Patent: US 8,758,593 B2
• Time in Patent Office: Days
• US Class Current: 205/775
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G01N 27/302 pH sensitive, e.g. quinhydron, antimony or hydrogen electrodes ion selective electrodes G01N27/333, glass electrodes G01N27/36
• CPC Class Codes: G01N 27/308 at least partially made of carbon
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001

Abstract

An electrochemical sensor and a method for using an electrochemical sensor are described where the electrochemical sensor comprises a working electrode having thereon one or more redox species that are sensitive to an analyte to be measured and a polymer coating that provides for interaction between the redox species and the analyte.

Claims

12. An electrochemical sensor for detecting or measuring an analyte in a fluid, comprising:

a working electrode, the working electrode comprising a first set of redox species, a second set of redox species and a polymer layer, wherein;

the first set of redox species comprises one or more redox species that are sensitive to the analyte;

the second set of redox species comprises one or more redox species that are insensitive to the analyte; and

the polymer layer is configured to prevent diffusion of at least one of the first and the second sets of redox species from the working electrode and to allow for an interaction between at least the first set of redox species and the analyte;

a counter electrode;

a reference electrode;

means to apply a varying potential to the working electrode;

means to measure a potential difference between the working electrode and the reference electrode;

means to measure a current flow between the working electrode and the counter electrode as the applied potential causes the first and the second set of redox species to undergo at least one of oxidation and reduction; and

a processor configured to process a presence or a measurement of the analyte from at least one of the measured potential difference and the measured current.

13. The electrochemical sensor of claim 12, wherein the working electrode comprises a first working electrode and a second working electrode and the first working electrode comprises the first set of redox species and the second working electrode comprises the second set of redox species.

14. The electrochemical sensor of claim 12, wherein at least one of the first set of redox species and the second set of redox species are chemically coupled with the working electrode.

15. The electrochemical sensor of claim 12, wherein the first redox species is chemically coupled with the working electrode and the second redox species is coated or deposited onto the working electrode.

16. The electrochemical sensor of claim 12, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises less than 1000 micrograms of polymer.

17. The electrochemical sensor of claim 12, wherein the polymer layer comprises a polystyrene polymer.

18. The electrochemical sensor of claim 17, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises less than 600 micrograms of the polystyrene polymer.

19. The electrochemical sensor of claim 17, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises between 100 and 500 micrograms of the polystyrene polymer.

20. The electrochemical sensor of claim 12, wherein the polymer layer comprises a polysulphone polymer.

21. The electrochemical sensor of claim 20, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises less than 600 micrograms of the polysulphone polymer.

22. The electrochemical sensor of claim 20, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises between 10 and 500 micrograms of the polysulphone polymer.

23. The electrochemical sensor of claim 12, wherein the means for measuring at least one of the potential difference and the current flow comprises at least one of a voltammetric device and a potentiostat.

24. The electrochemical sensor of claim 12, wherein the first set of redox species comprises one or more redox species sensitive to pH and the second set of redox species comprises one or more redox species insensitive to pH.

25. The electrochemical sensor of claim 24, wherein the one or more redox species sensitive to pH contain a hydroquinone or quinone moiety.

26. The electrochemical sensor in accordance with claim 24, wherein the one or more species insensitive to pH contain one of a ferrocene moiety, a ruthenocene moiety and a hexacyanometallate moiety.

27. The electrochemical sensor of claim 12, wherein a first surface area of the counter electrode is of the order of one to ten times that of a second surface area of the working electrode.

28. The electrochemical sensor of claim 12, wherein a first surface area of the counter electrode is less than one hundred times that of a second surface area of the working electrode.

31. The electrochemical sensor of claim 12, wherein the reference electrode comprises one of silver and silver chloride.

32. The electrochemical sensor of claim 13, wherein the second working electrode comprises carbon particles solvent cast with a ferrocene.

33. The electrochemical sensor of claim 12, wherein the processor processes the presence or measurement of the analyte form peak current flows produced by the oxidation or reduction of the first and the second sets of the redox species.

34. A method for electrochemically measuring an analyte in a fluid comprising:

contacting a working electrode with the fluid, wherein the working electrode comprises a conducting substrate coupled with a first set of redox species that are sensitive to the analyte and a second set of redox species that are insensitive to the analyte and a polymer layer;

using the polymer layer to prevent diffusion of at least one of the first set of redox species and the second set of redox species from the working electrode;

applying a varying potential between the working electrode and the reference electrode;

making voltammetric measurements of at least a current flow between the working electrode and the counter electrode as the varying potential causes the first and the second set of redox species to undergo at least one of oxidation and reduction and a potential difference between the working electrode and the reference electrode; and

processing the measurement of the analyte from the voltammetric measurements.

35. The method of claim 34, further comprising:

measuring a temperature of the fluid; and

using the measured temperature to calibrate the measurement of the analyte.

36. A method of manufacturing a working electrode for an electrochemical sensor for detecting or measuring an analyte in a fluid, the method comprising:

coupling at least a portion of the working electrode with a first set of redox species sensitive to the analyte;

depositing a second set of redox species insensitive to the analyte on the working electrode; and

coating at least a portion of the working electrode with a polymer.

1. A working electrode for an electrochemical sensor, comprising:

a conducting substrate;

a first set of redox species coupled with the conducting substrate, wherein the first set of redox species comprises one or more redox species that are sensitive to an analyte; and

a polymer layer covering at least an area of the conducting substrate coupled with the first set of redox species and configured to allow for an interaction between the first set of redox species and the analyte and to prevent diffusion of the first set of redox species from the working electrode.

2. The working electrode of claim 1, further comprising:

a second set of redox species disposed between the conducting substrate and the polymer layer, wherein the polymer layer is configured to prevent diffusion of the second set of redox species from the working electrode.

3. The working electrode of claim 1, wherein the first set of redox species is chemically bound to the conducting substrate.

4. The working electrode of claim 2, wherein the second set of redox species is chemically bound to the conducting substrate.

5. The working electrode of claim 1, wherein the working electrode comprises an electrode having a diameter between 1 and 5 millimeters and the polymer layer comprises less than 1000 micrograms of polymer.

6. The working electrode of claim 1, wherein the polymer layer comprises a polystyrene polymer.

7. The working electrode of claim 6, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises less than 600 micrograms of the polystyrene polymer.

8. The working electrode of claim 6, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises between 100 and 500 micrograms of the polystyrene polymer.

9. The electrochemical sensor of claim 1, wherein the polymer layer comprises a polysulphone polymer.

10. The electrochemical sensor of claim 9, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises less than 600 micrograms of the polysulphone polymer.

11. The working electrode of claim 9, wherein the working electrode has a diameter between 1 and 5 millimeters and the polymer layer comprises between 10 and 500 micrograms of the polysulphone polymer.

29. The electrochemical sensor of claim 1, further comprising a temperature probe for measuring a temperature of the fluid.

30. The electrochemical sensor of claim 29, wherein the processor uses the temperature to process the presence or the measurement of the analyte.

37. The method according to claim 36, wherein the step of coating the at least a portion of the working electrode with the polymer comprises one of solvent evaporation of the polymer onto the working electrode, spin coating the polymer onto the working electrode and dip coating the polymer onto the working electrode.

38. The method according to claim 36, wherein the step of depositing the second set of redox species insensitive to the analyte on the working electrode comprises contacting the working electrode coupled with the one or more redox species sensitive to the analyte with a solution comprising the second set of redox species insensitive to the analyte.

39. The method according to claim 36, wherein the step of depositing the second set of redox species insensitive to the analyte on the working electrode comprises depositing a solid form of the second set of redox species insensitive to the analyte onto the working electrode.

37-1. The method according to claim 36, wherein the step of coupling the at least a portion of the working electrode with the first set of redox species sensitive to the analyte comprises chemically coupling the first set of redox species sensitive to the analyte with the working electrode.