Reagent stripe for test strip

• US 20050016844A1
• Filed: 06/18/2004
• Published: 01/27/2005
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: Roche Diabetes Care Inc. (Roche Holding AG)
• Original Assignee: Roche Operations Limited (Roche Holding AG)
• Inventors: Fritz, Michael, Zapf, Udo, Mosoiu, Dan, Burke, David W., Wilsey, Chris, Marquant, Michael
• Granted Patent: US 7,727,467 B2
• Time in Patent Office: Days
• US Class Current: 204/403.10
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387
• CPC Class Codes: Y10T 156/1059 Splitting sheet lamina in plane intermediate of faces
• CPC Class Codes: Y10T 156/1084 of continuous or running length bonded web

Abstract

A test strip having a small sample-receiving chamber on the order of less than 1 microliter. The inventive test strip includes a reagent layer that extends across the width of the test strip and also extends to the sample-receiving end, such that the edges of the reagent layer are aligned with the side and dose receiving edges of the test strip. The hydrophilic reagent extending to the dosing edge of the strip promotes wicking of the sample into the test strip. The end and side edges of the reagent layer are preferably formed as part of a cutting process that forms individual test strips from a larger web, which results in a smooth and thin reagent layer with a uniform thickness, substantially covering the entire floor of the sample-receiving chamber. The inventive mass production process helps improve the reproducibility of the quantity, location, thickness and other properties of the reagent layer, which in turn improves the accuracy of the test result.

Claims

1. A test strip, comprising:

a base substrate having a working electrode and a counter electrode formed thereon and having two side edges and an end edge;

a spacing layer overlying the base substrate and having a void that at least partially defines a sample-receiving chamber;

a covering layer overlying the spacing layer; and

a reagent layer disposed in the sample-receiving chamber and covering a portion of the base substrate and at least one of the electrodes, the reagent layer extending under the spacing layer to the two side edges and being sandwiched between the spacing layer and the base substrate.

2. The test strip of claim 1, wherein the reagent layer extends to the end edge of the base substrate.

3. The test strip of claim 2, wherein the reagent layer defines a reagent layer end edge that is aligned with the end edge of the base substrate.

4. The test strip of claim 2, wherein a sample-receiving opening of the sample-receiving chamber is disposed at the end edge of the base substrate.

5. The test strip of claim 1, wherein the reagent layer defines two reagent layer side edges that are aligned with the side edges of the test strip.

6. The test strip of claim 1, wherein the spacing layer comprises a unitary spacing layer.

7. The test strip of claim 1, wherein the spacing layer comprises an adhesive material.

8. The test strip of claim 1, further comprising an adhesive layer disposed between the spacing layer and the base substrate.

9. The test strip of claim 8, wherein the adhesive layer is sandwiched between the spacing layer and the base substrate, the adhesive layer having an edge profile that is aligned with a peripheral edge of the sample-receiving chamber.

10. The test strip of claim 9, wherein the adhesive layer forms a seal around the periphery of the sample-receiving chamber.

11. The test strip of claim 1, wherein the test strip defines a central longitudinal axis and the sample-receiving chamber forms a channel oriented substantially parallel to the central longitudinal axis.

12. The test strip of claim 11, wherein the covering layer comprises a vent opening in communication with the sample-receiving chamber, the vent opening being positioned over a downstream portion of the sample-receiving chamber.

13. The test strip of claim 12, wherein the reagent layer extends to the downstream portion of the sample-receiving chamber over which the vent opening is positioned.

14. The test strip of claim 13, wherein the reagent layer extends beyond the downstream portion of the sample-receiving chamber over which the vent opening is positioned.

15. The test strip of claim 1, wherein the reagent layer has a thickness of between about 1 and 20 microns.

16. The test strip of claim 15, wherein the reagent layer has a thickness of between about 2 and 6 microns.

17. The test strip of claim 1, wherein the sample-receiving chamber has a height from about 50 μ

m to about 200 μ

m.

18. The test strip of claim 17, wherein the sample-receiving chamber has a height from about 120 μ

m to about 180 μ

m.

19. The test strip of claim 1, wherein the sample-receiving chamber has a volume of less than 1.0 μ

l.

20. The test strip of claim 1, wherein the sample-receiving chamber has a volume of less than 0.5 μ

l.

21. The test strip of claim 1, wherein the sample-receiving chamber has a volume from about 0.15 μ

l to about 1.4 μ

l.

22. The test strip of claim 21, wherein the sample-receiving chamber has a volume from about 0.4 μ

l to about 0.7 μ

l.

23. The test strip of claim 1, wherein the reagent layer has a uniform thickness, substantially devoid of a meniscus.

24. The test strip of claim 1, wherein the reagent layer includes one or more thickeners, viscosity modulators, film formers, stabilizers, buffers, detergents, gelling agents, fillers, film opening agents, coloring agents, and thixotropic agents.

25. The test strip of claim 1, wherein the reagent layer includes silica.

26. A test strip, comprising:

a test strip body having meter-insertion and sample-receiving ends, first and second sides, and a central longitudinal axis disposed substantially parallel to the two sides, the test strip body defining a downstream direction from the sample-receiving end to the meter-insertion end;

a base substrate defining the bottom of the test strip body and having an electrode formed thereon, the base substrate having edges aligned with the sample-receiving end and the first and second sides of the test strip body;

a spacing layer overlying the base substrate and having a void that at least partially defines a sample-receiving chamber; and

a reagent layer disposed in the sample-receiving chamber and covering a portion of the base substrate and the electrode, the reagent layer being sandwiched between the spacing layer and the base substrate and extending to the first and second sides and the sample-receiving end of the test strip body.

27. The test strip of claim 26, wherein the sample-receiving chamber defines a channel aligned with the longitudinal axis, the channel terminating at a sample-receiving opening disposed at the sample-receiving end, whereby the reagent layer extends to the sample-receiving opening.

28. The test strip of claim 27, further comprising a covering layer overlying the spacing layer, the covering layer comprising a vent opening in communication with the sample-receiving chamber, the vent opening aligned with the sample-receiving chamber at a location downstream of the sample-receiving opening.

29. The test strip of claim 28, wherein the vent opening comprises a slot formed in the covering layer.

30. The test strip of claim 28, wherein the reagent layer extends in the downstream direction to the vent opening.

31. The test strip of claim 30, wherein the reagent layer extends in the downstream direction beyond the vent opening.

32. The test strip of claim 30, wherein the reagent layer extends in the downstream direction beyond the electrode.

33. The test strip of claim 32, wherein the electrode comprises a counter electrode and a working electrode.

34. The test strip of claim 26, wherein the reagent layer defines first and second reagent layer side edges that are substantially aligned with the first and second sides of the test strip and a reagent layer end edge that is aligned with the sample-receiving end of the test strip.

35. The test strip of claim 26, wherein the spacing layer comprises a unitary spacing layer.

36. The test strip of claim 26, further comprising an adhesive layer disposed between the spacing layer and the base substrate.

37. The test strip of claim 36, wherein the adhesive layer is sandwiched between the spacing layer and the base substrate, the adhesive layer having an edge profile that is aligned with a peripheral edge of the sample-receiving chamber.

38. The test strip of claim 37, wherein the adhesive layer forms a seal around the periphery of the sample-receiving chamber.

39. The test strip of claim 26, wherein the reagent layer has a thickness of between about 1 and 20 microns.

40. The test strip of claim 39, wherein the reagent layer has a thickness of between about 2 and 6 microns.

41. The test strip of claim 26, wherein the reagent layer includes silica.

42. A method of manufacturing a test strip having first and second sides, sample-receiving and meter insertion ends, and a central longitudinal axis extending between the two ends, the method comprising:

(a) providing a web of base substrate material having first and second web edges;

(b) forming an electrode set on the web;

(c) applying a stripe of reagent material to the web and covering at least one electrode of the electrode set with the stripe, the stripe being oriented substantially parallel to the first web edge; and

(d) cutting the test strip from the web, the cutting defining the first and second sides and the sample-receiving end of the test strip, wherein during the cutting a portion of the reagent stripe is cut and removed from the sample-receiving end of the test strip and further wherein the test strip comprises a reagent layer extending to the sample-receiving end and the first and second sides of the test strip.

43. The method of claim 42, further comprising, after step (c):

providing a web of spacing material having a cavity formed therein;

aligning the cavity with the central longitudinal axis of the test strip and then laminating the spacing material to the web of base substrate material; and

then performing step (d), wherein the cavity at least partially defines a sample-receiving chamber.

44. The method of claim 43, wherein an adhesive is used for the laminating of the web of spacing material to web of base substrate material.

45. The method claim 43, further comprising, after laminating the web of spacing layer material, aligning and then laminating a web of covering layer material over the web of spacing layer material.

46. The method of claim 45, wherein the covering layer material forms a vent opening that communicates with the sample-receiving chamber.

47. The method of claim 46, wherein the electrode set comprises a plurality of spaced electrode sets, the cavity comprises a plurality of spaced cavities, the central longitudinal axis comprises a plurality of spaced central longitudinal axes, and step (d) comprises making a plurality of cuts to form a plurality of the test strips.

48. The method of claim 47, wherein the cutting in step (d) further comprises forming sample-receiving openings on the sample-receiving ends, each sample-receiving opening leading into a respective cavity, the reagent layer of each test strip extending to the sample-receiving opening.

49. The method of claim 43, wherein the electrode set comprises a plurality of spaced electrode sets, the central longitudinal axis comprises a plurality of spaced central longitudinal axes;

and step (d) comprises making a plurality of cuts to form a plurality of test strips.

50. The method of claim 43, wherein the reagent stripe is deposited on the web of base substrate as a wet composition at a thickness of between about 50 μ

m and about 100 μ

m.

51. The method of claim 50, wherein the reagent stripe is deposited on the web of base substrate as a wet composition at a thickness of between about 60 μ

m and about 80 μ

m.

52. The method of claim 50, wherein the reagent stripe dries to a thickness of between about 3 μ

m and about 20 μ

m.

53. The method of claim 42, wherein step (c) comprises applying the reagent stripe by a slot-die coating process.

54. The method of claim 42, wherein the electrode set comprises a counter electrode and a working electrode, both of which are covered by the reagent stripe.

55. The method of claim 42, wherein the reagent stripe is continuous.

56. The method of claim 42, wherein the meter insertion end is located proximate the second edge of the web of base substrate material.

57. A test strip, comprising:

a base substrate having a reagent layer disposed thereon;

a covering layer overlying the base substrate; and

a sample receiving chamber disposed between the base substrate and the covering layer, the sample receiving chamber terminating in a sample receiving opening located at a dosing edge of the test strip; and

wherein the reagent layer extends beyond a periphery of the sample receiving chamber and extends to the dosing edge of the test strip.

58. The test strip of claim 57, wherein the dosing edge comprises an end of the test strip.

59. The test strip of claim 57, wherein the dosing edge comprises a side of the test strip.

60. The test strip of claim 57, wherein the covering layer comprises a chamber cover and a body cover having a slot therebetween, the slot being in communication with the sample receiving chamber and defining a vent opening in the covering layer that allows air to escape as fluid enters the sample receiving chamber.

61. The test strip of claim 60, wherein the slot comprises a gap which spaces the body cover from the chamber cover.

62. The test strip of claim 61, wherein the gap extends across the width of the covering layer.

63. The test strip of claim 60, wherein the slot overlies the reagent layer.

64. The test strip of claim 57, further comprising an electrode disposed in the sample receiving chamber, the electrode being covered by the reagent layer.

65. The test strip of claim 57, further comprising a spacing layer disposed between the covering layer and the base substrate, the spacing layer defining a void portion that further defines the height and perimeter of the sample receiving chamber between the base and the covering layer.

66. The test strip of claim 65, wherein the reagent layer is sandwiched between the base substrate and the spacing layer.

67. The test strip of claim 66, wherein the reagent layer extends to a side edge and an end edge of the test strip.

68. The test strip of claim 57, wherein the dosing edge comprises an end of the test strip, and the reagent layer extends to both sides of the test strip.

69. The test strip of claim 57, wherein the reagent layer has a thickness of between about 2 and 6 microns.

70. The test strip of claim 57, wherein the sample-receiving chamber has a volume of less than 1.0 μ

l.

71. The test strip of claim 57, wherein the sample-receiving chamber has a volume of less than 0.5 μ

l.

72. The test strip of claim 57, wherein the sample-receiving chamber has a volume from about 0.15 μ

l to about 1.4 μ

l.

73. The test strip of claim 57, wherein the sample-receiving chamber has a volume from about 0.4 μ

l to about 0.7 μ

l.

74. The test strip of claim 57, wherein the reagent layer defines a reagent layer edge that is aligned with the dosing edge.

75. The test strip of claim 74, wherein the dosing edge comprises a side edge of the test strip.

76. The test strip of claim 74, wherein the dosing edge comprises an end edge of the test strip.