Method and system to determine hematocrit-insensitive glucose values in a fluid sample

• US 9,243,276 B2
• Filed: 08/29/2013
• Issued: 01/26/2016
• Est. Priority Date: 08/29/2013
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Malecha, Michael
• Primary Examiner(s): DIETERLE, JENNIFER M
• Application Number:
  US14/013,638
• Publication Number:
  US 20150060302A1
• Time in Patent Office: 880 Days
• US Class Current: 1/1
• 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

Abstract

Various embodiments of a technique to sample output signals at different time intervals from each of the electrodes in a biosensor to obtain respective glucose estimates including one where the output signals of at least one combination of electrodes measured at various time intervals are summed together to provide for a combined glucose estimate.

Claims

1. A glucose measurement system comprising:

a biosensor having a plurality of electrodes with a reagent disposed thereon; and

a meter including;

a microcontroller coupled to a power source, memory and the plurality of electrodes of the biosensor and in which the microcontroller is configured to;

apply a signal to at least two electrodes of the plurality of electrodes after application of a fluid sample proximate the at least two electrodes to start a test measurement sequence for an electrochemical reaction of the glucose in the fluid sample with the reagent;

obtain a first estimate representative of the glucose in the fluid sample from respective output signals from one of the at least two electrodes at a plurality of selected time intervals from the start of the test measurement sequence;

wherein the first estimate from the output signal of the one electrode out of the at least two electrodes is taken at time intervals at about 1.5 seconds, 1 seconds, 1.7 seconds, 1.2 seconds, and 0.7 seconds from the start of the test measurement sequence;

obtain a second estimate representative of the glucose in the fluid sample from respective output signals from a other electrode of the at least two electrodes at a plurality of selected time intervals from the start of the test measurement sequence;

wherein the second estimate from the output signal of the other electrode out of the at least two electrodes is taken at time intervals at about 4.4 seconds, 1.2 seconds, 2.5 seconds, 3.7 seconds, and 3.4 seconds from the start of the test measurement sequence;

obtain a third estimate representative of the glucose in the fluid sample from a combination of the respective output signals from the at least two electrodes of the plurality of electrodes at the plurality of specific time intervals from the start of the test measurement sequence; and

determine a final glucose value of the fluid sample from a median of all the estimates of the glucose in the fluid sample.

2. The system of claim 1, in which the first glucose estimate of the one electrode is obtained with an equation of a form:

3. The system of claim 1, in which the second glucose estimate of the other electrode is obtained with an equation of a form:

4. The system of claim 1, in which the microcontroller is configured to obtains a glucose estimate from a summation of the respective output signals of the at least two electrodes of the plurality of electrodes at time intervals at about 2.5 seconds, 0.7 seconds, 1.5 seconds, 1.2 seconds and 0.5 seconds from the start of the test measurement sequence.

5. The system of claim 4, in which the third glucose estimate of the at least two electrodes is obtained with an equation of a form:

6. A method of determining a glucose value from a fluid sample with a biosensor having at least two electrodes and reagent disposed thereon and a glucose meter having a microcontroller configured to connect to the biosensor and to a memory and a power source, the method comprising the steps of:

initiating a start of a test measurement sequence upon deposition of the fluid sample proximate the at least two electrodes of the biosensor;

applying an input signal to the at least two electrodes with the fluid sample to cause a transformation the glucose into an enzymatic by-product;

determining a plurality of glucose concentration estimates from a plurality of output signals from the at least two electrodes and the fluid sample;

wherein a first glucose estimate from the output signal of one electrode out of the at least two electrodes is taken at time intervals at about 1.5 seconds, 1 seconds, 1.7 seconds, 1.2 seconds, and 0.7 seconds from the start of the test measurement sequence;

wherein a second glucose estimate from the output signal of a other electrode out of the at least two electrodes is taken at time intervals at about 4.4 seconds, 1.2 seconds, 2.5 seconds, 3.7 seconds, and 3.4 seconds from the start of the test measurement sequence; and

deriving a final glucose concentration from a median of all of the plurality of glucose value estimates.

7. The method of claim 6, in which the determining comprises calculating the first glucose estimate from the output signals of the one out of the at least two electrodes with an equation of a form:

8. The method of claim 7, in which the determining comprises calculating the second glucose estimate from the output signals of the other out of the at least two electrodes with an equation of a form:

9. The method of claim 6, in which the determining of the glucose value comprises obtaining a combined glucose estimate from the sum of the signal outputs from the at least two electrodes at a third plurality of time intervals from the start of the test measurement sequence.

10. The method of claim 9, in which the determining comprises calculating the combined glucose estimate from the sum of the output signals of the at least two electrodes with an equation of a form: