Disposable test strips with integrated reagent/blood separation layer

• US 7,807,031 B2
• Filed: 06/13/2006
• Issued: 10/05/2010
• Est. Priority Date: 02/14/1996
• Status: Expired due to Fees

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Diabetes Diagnostics, Inc. (Johnson & Johnson)
• Inventors: Scott, David, Hall, Geoff, Plotkin, Elliot V., Davies, Oliver W. H., McAleer, Jerome F., Alvarez-Icaza, Manuel
• Primary Examiner(s): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US11/453,174
• Publication Number:
  US 20060260940A1
• Time in Patent Office: 1,575 Days
• Field of Search: 20440301-40315, 205/777.5, 205/778, 205/792
• US Class Current: 204/403.05
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52

Abstract

An improved disposable glucose test strip for use in a test meter of the type which receives a disposable test strip and a sample of blood from a patient and performs an electrochemical analysis is made using a non-conductive integrated reagent/blood separation layer containing a filler, an enzyme effective to oxidize glucose, e.g., glucose oxidase, and a mediator effective to transfer electrons from the enzyme. The integrated layer formulation is printed over a conductive carbon element to form a working electrode. The filler, for example a silica filler, is selected to have a balance of hydrophobicity and hydrophilicity such that one drying it forms a two-dimensional network on the surface of the conductive element. The response of this test strip is essentially temperature independent over relevant temperature ranges and is substantially insensitive to the hematocrit of the patient.

Claims

1. A disposable test strip for use in a test meter which receives a disposable test strip and a sample of blood and performs an electrochemical analysis of the amount of a blood analyte in the sample, comprising:

(a) a substrate;

(b) a first conductive element disposed on the substrate;

(c) a second conductive element disposed on the substrate in sufficient proximity to the first conductive element to allow the completion of an electrical circuit between the first and second conductive elements when a sample of blood is placed on the test strip;

(d) a non-conductive integrated reagent/blood separation layer disposed over the first conductive element, the integrated reagent/blood separation layer comprising reagents for the electrochemical detection of the analyte dispersed in a non-conductive matrix effective to exclude blood cells from the surface of the first conductive element while permitting access to the first conductive element by soluble electroactive species;

(e) contacts for making an electrical connection between the first and second conductive elements and the test meter; and

(f) an insulation layer disposed over at least the first conductive element, the insulation layer having a first aperture therein aligned with the first conductive element, the insulation layer having a peripheral portion adjacent to a surrounding area of the first aperture, wherein the non-conductive integrated reagent/blood separation layer is formed covering the entire first aperture and the peripheral portion.

2. The disposable test strip of claim 1, wherein a sufficient amount of the peripheral portion is covered by the non-conductive integrated reagent/blood separation layer to reduce variation in a measured signal as a result of lateral diffusion away from the first aperture.

3. The test strip of claim 1, wherein the integrated reagent/blood separation layer comprises an enzyme for oxidation of glucose and a redox mediator effective to transfer electrons from the enzyme to the first conductive element.

4. The test strip of claim 3, wherein the matrix comprises silica having both hydrophobic and hydrophilic surfaces.

5. The test strip according to claim 4, wherein the integrated reagent/blood separation layer is formed from an aqueous composition comprising 2 to 10% by weight of a binder;

3 to 10% by weight of silica;

8 to 20% by weight of the redox mediator; and

1000 to 5000 units of the enzyme per gram of the aqueous composition.

6. The test strip according to claim 5, wherein the enzyme is glucose oxidase.

7. The test strip according to claim 5, wherein the redox mediator is ferricyanide.

8. The test strip according to claim 3, wherein the enzyme is glucose oxidase.

9. The test strip according to claim 3, wherein the redox mediator is ferricyanide.

10. The test strip of claim 1, wherein the first and second conductive elements comprise conductive carbon.