TEST STRIPS, METHODS, AND SYSTEM OF MANUFACTURING TEST STRIP LOTS HAVING A PREDETERMINED CALIBRATION CHARACTERISTIC

• US 20090208734A1
• Filed: 01/15/2009
• Published: 08/20/2009
• Est. Priority Date: 01/18/2008
• Status: Abandoned Application

• Current Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: DUFFUS, Keith, LAMACKA, Martin, ALVAREZ-ICAZA, Manuel, MARSHALL, Robert, JARVIS, Tim, DELANEY, Kevin, PHIPPEN, Nicholas, RUSSELL, Robert, MACFIE, Gavin
• Application Number:
  US12/354,515
• Publication Number:
  US 20090208734A1
• Time in Patent Office: Days
• US Class Current: 428/332
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

Various embodiments of a technique in which test strip lots can be prepared without requiring a user to input any calibration information before performing a test measurement with a test strip from the test strip lots. In a first aspect, a method of manufacturing a plurality of test strips by adjusting amount of mediators and working electrode area is described. In another aspect, a method of preparing a reagent ink by adjusting the density of the reagent ink to substantially match a target density is described. In a further aspect, a method using a high numerical Shores Hardness squeegee in conjunction with high pressure is provided. In a further aspect, a method of performing an analyte measurement with a test meter, the test meter being configured to not receive a calibration input, and where the test strip manufactured to any one of the methods or techniques described and illustrated herein.

Claims

1. A method of manufacturing a test strip, the method comprising:

adjusting an amount of reduced mediator in a reagent ink, the reagent ink being disposed on a working electrode, to output a batch intercept that falls within a predetermined target batch intercept range; and

adjusting a working electrode area to output a batch slope that falls within a predetermined target batch slope range.

2. The method of claim 1, in which the working electrode area is adjusted by modifying a width of the working electrode.

3. The method of claim 1, in which the reduced mediator in the reagent ink is not greater than about 0.2% by weight of the reagent ink.

4. The method of claim 1, in which the reagent ink comprises the reduced mediator and an oxidized mediator where the reduced mediator is not greater than about 0.6% by weight of a sum of the reduced mediator and the oxidized mediator.

5. The method of claim 1, in which the width of the working electrode is from about 0.6 millimeters to about 0.8 millimeters.

6. The method of claim 1, in which the area of working electrode is from about 0.48 mm² to about 0.64 mm².

7. A test strip comprising:

a first and second working electrode both having a width of about 0.55 millimeters to about 0.85 millimeters; and

a reagent layer disposed proximate the working electrode, the reagent layer comprising

an oxidized mediator, a reduced mediator, and an enzyme, in which the reduced mediator is not greater than about 0.6% by weight of a sum of the reduced mediator and the oxidized mediator, so that the test strip has a predetermined target batch slope and predetermined target batch intercept.

8. A plurality of test strip batches in which each test strip comprises:

a substrate;

a conductive layer disposed on the substrate; and

a reagent layer disposed on the conductive layer, the reagent layer including an added amount of reduced mediator so that a batch intercept for each test strip batch of the plurality of test strip batches have a variation of less than about 15%.

9. The plurality of test strip batches of claim 8, in which the added amount of reduced mediator is based on a target intercept, a percent reduced mediator impurity, and a background intercept.

10. The plurality of test strip batches of claim 8, in which the background intercept is an average based on a plurality of batch intercepts from previously made test strip batches.

11. The plurality of test strip batches of claim 8, in which the percent reduced mediator impurity is a proportional amount of reduced mediator associated with an oxidized mediator as an impurity where the reagent layer includes an amount of the oxidized mediator.

12. The plurality of test strip batches of claim 9, in which the added amount of reduced mediator is determined by calculating a difference between the target intercept and the background intercept, dividing by a constant, and then subtracting an amount of reduced mediator impurity.

13. The plurality of test strip batches of claim 9, in which the added amount of reduced mediator F_add is generally defined by a relationship of

$F_{\mathrm{add}}=\frac{B_{\mathrm{target}}-B_0}{K_{\mathrm{int}}}-F_{\mathrm{imp}},$

where B_target is the target intercept, B₀ is the background intercept, K_int is a constant, and F_imp is an amount of reduced mediator associated with the oxidized mediator as an impurity.

14. The plurality of test strip batches of claim 8, further comprising a working electrode, the working electrode having a calculated area based on a target slope and a previous batch slope, the previous batch slope obtained from a previously made test strip batch.

15. The plurality of test strip batches of claim 14, in which the added amount of reduced mediator is based on a target intercept, a percent reduced mediator impurity, a background intercept, and the calculated area.

16. The plurality of test strip batches of claim 15, in which the added amount of reduced mediator F_add is generally defined by a relationship of

$F_{\mathrm{add}}=\frac{B_{\mathrm{target}}-B_0}{K_{\mathrm{int}}}-F_{\mathrm{imp}},$

where B_target is the target intercept, B₀ is the background intercept, K_int is a constant, and F_imp is an amount of reduced mediator associated with the oxidized mediator as an impurity and the background intercept and constant K_int are adjusted to take account of the calculated area.

17. The plurality of test strip batches of claim 8, in which the plurality of test strip batches comprises from about 10 batches to about 100 batches.

18. The plurality of test strip batches of claim 17, in which the variation of 15% or less in batch intercepts is determined by calibrating about 600 or more test strips.

19. A plurality of test strip batches in which each test strip comprises:

a substrate; and

carbon ink disposed on the substrate by a squeegee through a metallic screen to define at least one carbon electrode track having a length as measured along a virtual line perpendicular to an axis between two side edges of the at least one track, in which any variations in the length compared to another length of another printed carbon track of at least one other test strip in the plurality of test strip batches is less than about 3.5%.

20. A method of manufacturing a reagent formulation, the method comprising:

(i) mixing a solution that includes a rheological control agent, a mediator and an enzyme for a predetermined amount of time;

(ii) measuring a density of the solution; and

(iii) if the density is not greater than a threshold, continuing to mix the solution for a predetermined amount of time such that the density is about equal to or greater than the threshold.

21. The method of claim 20, in which the targeted density is any value from about 1 gram per cm³ to about 1.25 grams per cm³.

22. A reagent formulation for coating on a working electrode of a test strip, the reagent formulation comprising:

(i) a rheological control agent;

(ii) a mediator; and

(iii) an enzyme in a mixture with the agent and mediator to generally form a reagent having a density of any value from about 1 grams per cm³ to about 1.25 grams per cm³.

23. An analyte test strip comprising:

a substrate; and

carbon ink disposed on the substrate by a squeegee through a metallic screen to define carbon electrode tracks with each carbon electrode track extending along a longitudinal axis so that any variations in a length of the carbon electrode track as measured along a virtual line perpendicular to an axis between two side edges of a carbon electrode track in one strip compared to a length of a carbon electrode track in other test strips, of a predetermined sample of test strips, is less than about 3.5%.

27. The test strip of any one of claims 23 to 26, in which the at least one track comprises two carbon tracks printed on a substrate to define a test strip with a gap between the tracks, in which the gap do not vary by more than 30% from a predetermined value.

28. The test strip of any one of claims 23 to 26, in which the substrate comprises a polymer substrate.

29. The test strip of claim 28, in which the polymer substrate comprises a polymer selected from a group consisting essentially of polyester, polyethylene terephthalate, and combinations thereof.

30. The test strip of claim 29, in which the substrate comprises a generally planar configuration having a thickness of approximately 0.35 millimeter, a width of about 5.5 millimeters, and a length of about 27.5 millimeters.

31. The test strip of claim 27, in which the predetermined value comprises approximately 150 microns.

24. An analyte test strip comprising:

a substrate; and

a plurality of carbon electrode tracks disposed on the substrate via carbon ink deposition by a squeegee of greater than 55 Shore Hardness A scale through a metallic screen so that any minimum gap between any two working electrode tracks do not vary by more than 30% from a predetermined value.

25. An analyte test strip comprising:

a substrate; and

carbon ink disposed on the substrate by a squeegee through a metallic screen to define at least one carbon electrode track having a length as measured along a virtual line perpendicular to an axis between two side edges of the at least one track, in which any variations in the length compared to another length of another printed carbon track of at least one other test strip is less than about 3.5%.

26. An analyte test strip comprising:

a substrate; and

carbon ink disposed on the substrate by a squeegee through a metallic screen to define at least one carbon electrode track having a length as measured along a virtual line perpendicular to an axis between two side edges of the at least one track, in which any variations in the length compared to another length of another printed carbon track of at least one other test strip is less than about 2.5%.