Method and apparatus for background current arrangements for a biosensor

• US 7,729,737 B2
• Filed: 11/14/2006
• Issued: 06/01/2010
• Est. Priority Date: 11/22/2005
• Status: Active Grant

• Current Assignee: Konamite Limited
• Original Assignee: Isense Corporation
• Inventors: Ward, W. Kenneth
• Primary Examiner(s): Nasser; Robert L
• Assistant Examiner(s): D'ANGELO, MICHAEL J
• Application Number:
  US11/559,521
• Publication Number:
  US 20070135696A1
• Time in Patent Office: 1,295 Days
• Field of Search: 600347-348, 600316-317, 600/322, 600/365
• US Class Current: 600/347
• 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

Abstract

Embodiments of the present invention provide for raising a background current setting for a biosensor above the actual (measured) background current present (i.e., overestimating the background current), particularly in the hypoglycemic range, to improve sensor accuracy and decrease the chance of glucose value overestimation by the sensor.

Claims

1. A method, comprising:

determining by a computing device an initial background current value of an analyte sensor;

determining by the computing device for the analyte sensor an initial analyte sensor output value using the initial background current value;

adjusting by the computing device the initial background current value by a factor based on the determined initial analyte sensor output value to form an adjusted background current value; and

forming by the computing device an adjusted analyte sensor output value using the adjusted background current value.

2. The method of claim 1, wherein said factor is a multiplication factor applied to the initial background current value.

3. The method of claim 2, wherein said multiplication factor is less than 3.

4. The method of claim 1, wherein said factor comprises an increase or decrease of the initial background current value to an adjusted background current value selected from a predefined list of acceptable adjusted background current values.

5. The method of claim 4, wherein said predefined list of acceptable adjusted background current values comprises 0, 0.8, 1.5, 2.2, and 3.0 nA.

6. The method of claim 1, wherein the adjusted background current value is greater than the initial background current value.

7. The method of claim 1, wherein said based on the initial analyte sensor output value comprises determining by the computing device whether the initial analyte sensor output value falls within a predetermined range.

8. The method of claim 7, wherein said predetermined range is 70 mg/dl and below.

9. The method of claim 8, wherein said adjusted background current value is approximately 1.3-1.7 nA.

10. The method of claim 7, wherein said predetermined range is above 70 mg/dl.

11. The method of claim 10, wherein said adjusted background current value is approximately 0.6-1.0 nA.

12. The method of claim 1, wherein said determining by a computing device an initial background current value comprises providing by a computing device an arbitrary background current level within a range of approximately 0.5 to 2.0 nA.

13. The method of claim 1, wherein said adjusted analyte sensor output value is displayed on an associated display device.

14. The method of claim 1, wherein said adjusted background current value is further adjusted in real time as the adjusted analyte sensor output value changes.

15. The method of claim 1, wherein said using the initial background current value comprises subtracting by the computing device the initial background current value from a first measured analyte sensor output value to form said initial analyte sensor output value, and said using the adjusted background current value comprises subtracting by the computing device the adjusted background current value from a second measured analyte sensor output value to form said adjusted analyte sensor output value.

16. An apparatus comprising:

a storage medium having stored therein a plurality of programming instructions designed to enable the apparatus, when the programming instructions are executed, to determine an initial background current value of an analyte sensor, determine for the analyte sensor in use an initial analyte sensor output value using the initial background current value, adjust the initial background current value by a factor based on the determined initial analyte sensor output value to form an adjusted background current value, and form an adjusted analyte sensor output value using the adjusted background current value; and

a processor coupled to the storage medium to execute the plurality of programming instructions.