Sensor having electrode for determining the rate of flow of a fluid

• US 20030214304A1
• Filed: 05/14/2002
• Published: 11/20/2003
• Est. Priority Date: 05/14/2002
• Status: Active Grant

• Current Assignee: Abbott Laboratories Incorporated
• Original Assignee: Abbott Laboratories Incorporated
• Inventors: Jobst, Gerhard, Urban, Gerald, Moser, Isabella, Karinka, Shridhara Alva, Petrou, Panagiota S., Herberth, Uwe, Tietjen, Uwe
• Granted Patent: US 6,801,041 B2
• Time in Patent Office: Days
• US Class Current: 324/444
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01F 1/64 by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects G01F1/58 takes precedence

Abstract

Sensors that are capable measuring the rate of flow of a fluid that passes over the electrodes of the sensor. In these sensors, an electrode, designated the flow rate-determining electrode, is used in conjunction with the conventional electrodes, e.g., the working electrode, the reference electrode, and the counter electrode, to determine the rate of flow of the fluid. In one aspect, this invention provides a sensor for measuring the concentration of an analyte in a sample of fluid when the sample flows continuously over the electrodes of the sensor, especially when the rate of flow of the sample is relatively low. In another aspect, this invention provides a method for measuring the concentration of an analyte in a sample of fluid, wherein the rate of flow of the sample varies during the period of time that the sensor is in place. In a preferred embodiment, the sensor employs four electrodes, namely, a working electrode, a reference electrode, a counter electrode, and a flow rate-determining electrode. Alternatively, a single electrode that performs both the function of the reference electrode and the function of the counter electrode can replace the reference electrode and the counter electrode. In addition, a dummy electrode or a blank electrode can be used to compensate for interference from electrochemically active species. The reagent(s) specific to the analyte of interest is required to be deposited on the working electrode.

Claims

1. A sensor for determining the rate of flow of a fluid, comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with:

(a) a working electrode;

(b) at least one flow rate-determining electrode;

(c) a reference electrode; and

(d) a counter electrode.

2. The sensor of claim 1, wherein a reaction layer overlies said working electrode and a diffusion layer overlies said reaction layer.

3. The sensor of claim 2, wherein said reaction layer includes an enzyme.

4. The sensor of claim 3, wherein said enzyme is an oxidase.

5. The sensor of claim 4, wherein said enzyme is selected from the group consisting of alcohol oxidase, cholesterol oxidase, glucose oxidase, glutamate oxidase, and lactate oxidase.

6. The sensor of claim 2, wherein a semi-impermeable layer is placed between said working electrode and said reaction layer.

7. The sensor of claim 1, wherein a diffusion layer overlies said at least one flow rate-determining electrode.

8. The sensor of claim 4, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

9. The sensor of claim 1, wherein a reaction layer overlies said working electrode, a diffusion layer overlies said reaction layer, and a layer of material that converts electrochemically active material to non-reactive material overlies said diffusion layer.

10. The sensor of claim 9, wherein a semi-impermeable layer is placed between said working electrode and said reaction layer.

11. The sensor of claim 9, wherein a reaction layer overlies said at least one flow rate-determining electrode and a diffusion layer overlies said reaction layer.

12. The sensor of claim 11, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

13. The sensor of claim 1, wherein two flow rate-determining electrodes are employed, one of said flow rate-determining electrodes being upstream of said working electrode and the other of said flow rate-determining electrodes being downstream of said working electrode.

14. A method for determining the rate of flow of a sample of fluid in a sensor having a channel, wherein said sample of fluid flows in said channel, said method comprising the steps of:

(a) providing the sensor of claim 1;

(b) determining responses of said working electrode and responses of said flow rate-determining electrode at known rates of flow of fluid;

(c) establishing a relationship between said responses measured in step (b) and said rates of flow of fluid in step (b);

(d) determining the response of said working electrode and the response of said flow rate-determining electrode at an unknown rate of flow of said sample of fluid; and

(e) determining the value of said unknown rate of flow of said sample of fluid by means of said relationship established in step (c).

15. The method of claim 14, wherein said responses result from the formation of an electrochemically active material.

16. The method of claim 15, wherein said electrochemically active material is hydrogen peroxide.

17. The method of claim 15, wherein said electrochemically active material is oxygen.

47. A method for determining the concentration of an analyte in a sample of fluid, wherein said sample of fluid flows at an unknown rate of flow, said method comprising the steps of:

(a) providing the sensor of claim 1;

(b) introducing said sample of fluid to said flow channel of said sensor, said rate of flow of said sample being unknown;

(c) determining the response of said working electrode and the response of said flow rate-determining electrode at said unknown rate of flow of said sample of fluid;

(d) determining the value of said unknown rate of flow of said sample of fluid by means of a calibration relationship;

(e) determining the uncorrected value of concentration of said analyte in said sample of fluid by means of a calibration relationship; and

(f) determining the corrected value of concentration of said analyte in said sample of fluid by correcting said value of uncorrected concentration of said analyte by means of said rate of flow determined in step (d).

18. A sensor for determining the rate of flow of a fluid, comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with:

(a) a working electrode;

(b) at least one flow rate-determining electrode; and

(c) a dual-purpose electrode that performs the functions of a reference electrode and a counter electrode.

19. The sensor of claim 18 wherein a reaction layer overlies said working electrode and a diffusion layer overlies said reaction layer.

20. The sensor of claim 19, wherein said reaction layer includes an enzyme.

21. The sensor of claim 20, wherein said enzyme is an oxidase.

22. The sensor of claim 21, wherein said enzyme is selected from the group consisting of alcohol oxidase, cholesterol oxidase, glucose oxidase, glutamate oxidase, and lactate oxidase.

23. The sensor of claim 19, wherein a semi-impermeable layer is placed between said working electrode and said reaction layer.

24. The sensor of claim 18, wherein a diffusion layer overlies said at least one flow rate-determining electrode.

25. The sensor of claim 21, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

26. The sensor of claim 18, wherein a reaction layer overlies said working electrode, a diffusion layer overlies said reaction layer, and a layer of material that converts electrochemically active material to non-reactive material overlies said diffusion layer.

27. The sensor of claim 26, wherein a semi-impermeable layer is placed between said working electrode and said reaction layer.

28. The sensor of claim 26, wherein a reaction layer overlies said at least one flow rate-determining electrode and a diffusion layer overlies said reaction layer.

29. The sensor of claim 28, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

30. The sensor of claim 18, wherein two flow rate-determining electrodes are employed, one of said flow rate-determining electrodes being upstream of said working electrode and the other of said flow rate-determining electrodes being downstream of said working electrode.

31. A method for determining the rate of flow of a sample of fluid in a sensor having a channel, wherein said sample of fluid flows in said channel, said method comprising the steps of:

(a) providing the sensor of claim 18;

(b) determining responses of said working electrode and responses of said flow rate-determining electrode at known rates of flow of fluid;

(c) establishing a relationship between said responses measured in step (b) and said rates of flow of fluid in step (b);

(d) determining the response of said working electrode and the response of said flow rate-determining electrode at an unknown rate of flow of said sample of fluid; and

(e) determining the value of said unknown rate of flow of said sample of fluid by means of said relationship established in step (c).

32. The method of claim 31, wherein said responses result from the formation of an electrochemically active material.

33. The method of claim 32, wherein said electrochemically active material is hydrogen peroxide.

34. The method of claim 32, wherein said electrochemically active material is oxygen.

48. A method for determining the concentration of an analyte in a sample of fluid, wherein said sample flows at an unknown rate of flow, said method comprising the steps of:

(a) providing the sensor of claim 18;

(b) introducing said sample of fluid to said flow channel of said sensor, said rate of flow of said sample being unknown;

(c) determining the response of said working electrode and the response of said flow rate-determining electrode at said unknown rate of flow of said sample of fluid;

(d) determining the value of said unknown rate of flow of said sample of fluid by means of a calibration relationship;

(e) determining the uncorrected value of concentration of said analyte in said sample of fluid by means of a calibration relationship; and

(f) determining the corrected value of concentration of said analyte in said sample of fluid by correcting said the uncorrected value of concentration of said analyte by means of said rate of flow determined in step (d).

35. A method for determining the rate of flow of a sample of fluid in a sensor having a channel, and the direction of flow said sample of fluid in said sensor, wherein said sample of fluid flows in said channel, said method comprising the steps of:

(a) providing a sensor for determining the rate of flow of a fluid, said sensor comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with;

(1) a working electrode;

(2) two flow rate-determining electrodes, one of said flow rate-determining electrodes being upstream of said working electrode and the other of said flow rate-determining electrodes being downstream of said working electrode;

(3) a reference electrode; and

(4) a counter electrode;

(b) determining responses of said working electrode and responses of said flow rate-determining electrodes at known rates of flow of fluid and in a first given direction of flow of fluid;

(c) establishing a relationship between the responses measured in step (b) and the rates of flow of fluid in step (b) and the direction of flow of fluid in step (b);

(d) determining responses of said working electrode and responses of said flow rate-determining electrodes at known rates of flow of fluid and in a second given direction of flow of fluid;

(e) establishing a relationship between the responses measured in step (d) and the rates of flow of fluid in step (d) and the direction of flow of fluid in step (d);

(f) determining the response of said working electrode and the response of one of said flow rate-determining electrodes at an unknown rate of flow of said sample of fluid and in an unknown direction of flow of said sample of fluid; and

(g) determining the direction of flow of said sample of fluid and said value of said unknown rate of flow said sample of fluid by means of said relationships established in step (c) and step (e).

36. A method for determining the rate of flow of a sample of fluid in a sensor having a channel, and the direction of flow of said sample of fluid in said sensor, wherein said sample of fluid flows in said channel, said method comprising the steps of:

(a) providing a sensor for determining the rate of flow of a sample of fluid, said sensor comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with;

(1) a working electrode;

(2) two flow rate-determining electrodes, one of said flow rate-determining electrodes being upstream of said working electrode and the other of said flow rate-determining electrodes being downstream of said working electrode;

(3) a dual-purpose electrode that performs the functions of a reference electrode and a counter electrode;

(b) determining responses of said working electrode and responses of said flow rate-determining electrodes at known rates of flow of fluid and in a first given direction of flow of fluid;

(c) establishing a relationship between the responses measured in step (b) and the rates of flow of fluid in step (b) and the direction of flow of fluid in step (b);

(d) determining responses of said working electrode and responses of said flow rate-determining electrodes at known rates of flow of fluid and in a second given direction of flow of fluid;

(e) establishing a relationship between the responses measured in step (d) and the rates of flow of fluid in step (d) and the direction of flow of fluid in step (d);

(f) determining the response of said working electrode and the response of one of said flow rate-determining electrodes at an unknown rate of flow of said sample of fluid and in an unknown direction of flow of said sample of fluid; and

(g) determining the direction of flow of said sample of fluid and said value of said unknown rate of flow of said sample of fluid by means of said relationships established in step (c) and step (e).

37. A sensor for determining the rate of flow of a fluid, said sensor comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with:

(a) a flow rate-determining electrode;

(b) a reference electrode; and

(c) a counter electrode.

38. The sensor of claim 37, wherein a diffusion layer overlies said flow rate-determining electrode.

39. The sensor of claim 37, wherein a reaction layer overlies said flow rate-determining electrode and a diffusion layer overlies said reaction layer.

40. The sensor of claim 39, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

41. A method for determining the rate of flow of a sample of fluid containing an analyte, said method comprising the steps of:

(a) providing the sensor of claim 37;

(b) determining responses of said flow rate-determining electrode at known rates of flow of samples of fluid, said samples of fluid having known concentrations of said analyte;

(c) establishing a relationship between said responses of said flow rate-determining electrode and said known rates of flow of samples of fluid having known concentrations of said analyte;

(d) determining the response of said flow rate-determining electrode where the rate of flow of fluid is unknown and the concentration of analyte in said fluid is known; and

(e) determining the rate of flow of fluid from said relationship of step (c).

42. A sensor for determining the rate of flow of a fluid, said sensor comprising a channel through which said fluid flows, said channel constructed so that said fluid is capable of coming into contact with:

(a) a flow rate-determining electrode; and

(b) a dual-purpose electrode that performs the functions of a reference electrode and a counter electrode.

43. The sensor of claim 42, wherein a diffusion layer overlies said flow rate-determining electrode.

44. The sensor of claim 42, wherein a reaction layer overlies said flow rate-determining electrode and a diffusion layer overlies said reaction layer.

45. The sensor of claim 44, wherein a semi-impermeable layer is placed between said at least one flow rate-determining electrode and said reaction layer.

46. A method for determining the rate of flow of a sample of fluid containing an analyte, said method comprising the steps of:

(a) providing the sensor of claim 42;

(b) determining responses of said flow rate-determining electrode at known rates of flow of samples of fluid, said samples of fluid having known concentrations of said analyte;

(c) establishing a relationship between said responses of said flow rate-determining electrode and said known rates of flow of samples of fluid having known concentrations of said analyte;

(d) determining the response of said flow rate-determining electrode where the rate of flow of fluid is unknown and the concentration of analyte in said fluid is known; and

(e) determining the rate of flow of fluid from said relationship of step (c).