Electrochemical sensor

• US 20090321278A1
• Filed: 08/31/2006
• Published: 12/31/2009
• Est. Priority Date: 09/01/2005
• Status: Active Grant

• Current Assignee: Palintest Limited (Halma PLC)
• Original Assignee: Palintest Limited (Halma PLC)
• Inventors: Birch, Stephen William, Southerland, John
• Granted Patent: US 8,142,641 B2
• Time in Patent Office: Days
• US Class Current: 205/778.5
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/0052 for gaseous halogens

Abstract

A electrochemical sensor comprising a mounting having screen printed array of electrodes located thereon, the array comprising a reference electrode, a counter electrode and a plurality of working electrodes, wherein the working electrodes are each overlaid with an insulating layer of insulating material, the insulating layer having an array of apertures, exposing a respective array of working regions of the working electrodes, and a method of making same by applying screen printing technic, and a method of using same for chlorine determination.

Claims

1. An electrochemical sensor comprising a mounting having a screen printed array of electrodes located thereon, the array comprising a reference electrode, a counter electrode and a plurality of working electrodes, wherein the working electrodes are each overlaid with an insulating layer of insulating material, the insulating layer having an array of apertures exposing a respective array of working regions of the working electrodes, wherein a reagent layer overlies said apertures within the insulating layer.

2. A sensor as claimed in claim 1 adapted for use in detection and/or assay of an analyte.

3. A sensor as claimed in claim 1, in which the analyte is at least one form of chlorine.

4. A sensor as claimed in claim 1 in which the analyte is at least one form of ammonia.

5. A sensor as claimed in claim 3 adapted for use in simultaneous measurement of free and total chlorine and/or free and combined chlorine.

6. A sensor as claimed in claim 4, wherein a conductive polymer is present on a working electrode or a conductive polymer layer has been printed onto the sensor containing conductive ink as a working electrode.

7. A sensor as claimed in claim 1, including working electrodes of carbon.

8. A sensor as claimed in claim 7, in which the said working electrodes of carbon have been screen printed onto the sensor.

9. A sensor as claimed in claim 1, including four generally parallel tracks comprising a reference electrode, two working electrodes and a counter electrode.

10. A sensor as claimed in claim 1, which is disposable, for example, by the inclusion therein of a fuseable link.

11. A sensor as claimed in claim 1, comprising a laminar sheet or strip of insulating polymeric material upon which successive layers have been applied by screen printing.

12. A sensor as claimed in claim 1, wherein the apertures in said array have a dimension of 50 to 400 μ

M.

13. A sensor as claimed in claim 12, wherein the said dimension is 100 to 200 μ

M.

14. A sensor as claimed in claim 1, wherein the apertures are circular.

15. A sensor as claimed in claim 1, wherein the array comprises 100 to 500 apertures.

16. A sensor as claimed in claim 15, wherein the array comprises 50 to 200 apertures.

17. A sensor as claimed in claim 10, wherein the array comprises 80 to 120 apertures.

18. A sensor as claimed in claim 11, wherein the array comprises 95 apertures.

19. A sensor as claimed in claim 1, wherein a plurality of tracks of highly conductive printable ink have been screen printed onto the mounting, each in contact with an electrical contact of the sensor.

20. A sensor as claimed in claim 19 in which the ink is of silver or is silver chloride based,

21. A sensor as claimed in claim 19, wherein working electrodes of the sensor deposited on said tracks are of carbon or gold.

22. A sensor as claimed in claim 1, in which the reagent layer comprises a porous layer impregnated with one or more reagents.

23. A sensor as claimed in claim 1, adapted for use in the assay of total chlorine present in a test solution.

24. A sensor as claimed in claim 1, in which said reagent layer is impregnated with an iodide such as potassium iodide, and with or without a buffer such as potassium phthalate.

25. A sensor as claimed in claim 1, in which the reagent layer includes a redox indicator able to react with chlorine in its free form.

26. A sensor as claimed in claim 25, in which the said redox indicator comprises DPD or TMB optionally in the presence of a buffer, for example, phosphate buffer.

27. A sensor as claimed in claim 26, in which the reagent layer further comprises polyvinylpyrrolidone and/or hydroxyethylcellulose.

28. A sensor as claimed in claim 1, in which the reagent layer has been deposited by screen printing or microdosing,

29. A method of making a sensor as claimed in claim 1, comprising providing a mounting in the form of insulating polymeric material such as plastics material, depositing a silver or other metallic conductive track thereon and wherein each electrode layer as defined in claim 1 is deposited upon the sensor by screen printing.

30. A method as claimed in claim 29, in which a deposition stage involves deposition of the insulating layer over the working electrodes such that said layer is provided with said array of apertures exposing working regions of said electrodes.

31. A method as claimed in claim 30, in which said deposition is effected by screen printing of the said insulating layer with an array of microapertures.

32. A method as claimed in claim 29, wherein additionally one or more liquid reagents are deposited upon the sensor within a reagent layer of a working electrode.

33. A method as claimed in claim 32, in which the reagent(s) is (are) absorbed into said layer and allowed to dry before use.

34. A method of detecting an analyte in a test solution involving use of a sensor as claimed in claim 1.

35. A method as claimed in claim 34, including assessing the analyte,

36. A method as claimed in claim 34, wherein the analyte comprises at least one form or chlorine and/or ammonia,

37. A method as claimed in claim 34, in which the sensor includes a reagent layer.

38. A method as claimed in claim 37, carried out on a test solution in the absence of other assay reagents in the test solution.

39. A method as claimed in claim 37, carried out in the absence of additional or supplementary calibration by the user of the method.

40. A method as claimed in claim 34, for the detection of free and total chlorine species in an aqueous test solution or free and combined chlorine species therein.

41. A method as claimed in claim 34, for the detection of ammonium species in an aqueous test solution.