Method of reducing the effect of direct interference current in an electrochemical test strip

• US 7,653,492 B2
• Filed: 10/29/2004
• Issued: 01/26/2010
• Est. Priority Date: 10/31/2003
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Whyte, Lynsey, Baskeyfield, Damian Edward Haydon, Leiper, Elaine, Marshall, Robert, Davies, Oliver William Hardwicke
• Primary Examiner(s): Nghiem; Michael P
• Application Number:
  US10/577,586
• Publication Number:
  US 20070276621A1
• Time in Patent Office: 1,915 Days
• Field of Search: 702/17, 702/22, 702/23, 702/104, 702189-191, 702/25, 702/50, 702/64, 702/65, 702/100, 204/403.01, 204/403.11, 204/403.14, 205/775, 205/779, 600/345, 600/347
• US Class Current: 702/22
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150282 for piercing elements, e.g. blade, lancet, canula, needle
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150435 Specific design of proximal end
• CPC Class Codes: A61B 5/150503 Single-ended needles hollow piercing element tip design A61B5/150396, needle sets for catheters A61M25/06, needles for bringing media into the body A61M5/32
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

This invention describes a method of reducing the effect of interfering compounds in a bodily fluid when measuring an analyte using an electrochemical sensor. In particular, the present method is applicable to electrochemical sensors where the sensor includes a substrate, first and second working electrodes, and a reference electrode and either the first and second or only the second working electrode include regions which are bare of reagent. In this invention, an algorithm is described with mathematically corrects for the interference effect using the test strip embodiments of the present invention.

Claims

1. A method of reducing interferences in an electrochemical sensor comprising:

measuring a first current using a first working electrode, said first working electrode having an area being covered by a reagent layer;

measuring a second current using a second working electrode having a covered area coated by the reagent layer and an uncovered area not coated by the reagent layer such that intereferent current produced at the uncovered area is proportional to interferent current produced overall; and

calculating, by a meter, a corrected current value representative of a glucose concentration using the measured first current, the measured second current, and a ratio of said covered area to said uncovered area of said second working electrode to reduce the effects of interferents.

2. The method of claim 1, wherein said corrected current value is calculated using the equation:

3. The method of claim 1, in which the interferent comprises one or more of acetaminophen, gentisic acid, uric acid, and combinations thereof.

6. The method of one of claim 1 or claim 4, in which the interferent comprises one or more of acetaminophen, gentisic acid, uric acid, and combinations thereof.

4. A method of reducing interferences in an electrochemical sensor comprising:

measuring a first current using a first working electrode, wherein said reagent layer partially covers said first working electrode, said first working electrode having a first coated area covered by said reagent layer and a first uncoated area not covered by said reagent layer;

measuring a second current using a second working electrode, wherein said reagent layer partially covers said second working electrode, said second working electrode having a second covered area coated by said reagent layer and a second uncovered area not coated by said reagent layer such that intereferent current produced at the uncovered area is proportional to interferent current produced overall; and

calculating, by a meter, a corrected current value representative of a glucose concentration using the measured first current, the measured second current, and a ratio of said covered area to said uncovered area of said first and said second working electrodes to reduce the effects of interferents.

5. The method of claim 4, wherein said corrected current value is calculated using the equation:

7. A method of reducing interferences in an electrochemical sensor having a first and second working electrodes disposed on a substrate and an insulation disposed over electrodes and the substrate, the insulation having an opening to allow a reagent to contact portions of the first and second working electrodes, the method comprising:

measuring a first current using a first working electrode, said first working electrode having an area coated by the reagent;

measuring a second current using a second working electrode having an area coated by the reagent and an area uncoated by the reagent such that intereferent current produced at the uncoated area is proportional to interferent current produced overall; and

calculating, by a meter, a corrected current value representative of a glucose concentration using the measured first current, the measured second current, and a ratio of said coated area to said uncoated area of said second working electrode to reduce the effects of interferents.

8. The method of claim 7, in which said corrected current value is calculated using the equation:

9. A method of reducing interferences in an electrochemical sensor having a first and second working electrodes disposed on a substrate and an insulation disposed over electrodes and the substrate, the insulation having an opening to allow a reagent to contact portions of the first and second working electrodes, the method comprising:

measuring a first current at using first working electrode having a first coated area covered by the reagent and a first uncoated area not covered by the reagent;

measuring a second current using a second working electrode having a second covered area coated by said reagent and a second uncovered area not coated by said reagent such that intereferent current produced at the uncovered area is proportional to interferent current produced overall; and

calculating, by a meter, a corrected current value representative of a glucose concentration using the measured first current, the measured second current, and a ratio of said covered area to said uncovered area of said first and said second working electrodes to reduce the effects of interferents.

10. The method of claim 9, wherein said corrected current value is calculated using the equation: