Method and system to determine erroneous measurement signals during a test measurement sequence

• US 9,459,231 B2
• Filed: 08/29/2013
• Issued: 10/04/2016
• 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): NOGUEROLA, ALEXANDER STEPHAN
• Application Number:
  US14/013,516
• Publication Number:
  US 20150060299A1
• Time in Patent Office: 1,132 Days
• US Class Current: 1/1
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• 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: G01N 27/3275 Sensing specific biomolecules, e.g. nucleic acid strands, based on an electrode surface reaction

Abstract

Various embodiments that allow a more accurate electrochemical test strip measurement by identifying erroneous output signals during a glucose measurement thereby ensuring a much more accurate glucose test system.

Claims

1. A glucose measurement system comprising:

a biosensor having a plurality of electrodes including at least two 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;

drive a signal to the at least two electrodes when a fluid sample having glucose is deposited 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;

measure an output signal from at least one electrode during the electrochemical reaction over a series of time intervals to obtain a magnitude of the output signal for each time interval;

determine an output differential as a difference in the respective magnitudes of the output signal for at least two consecutive time intervals within a predetermined time window during the test measurement sequence;

if the output differential is greater than a predetermined threshold then increment an index value as equal to the sum of both a previous value of the index and the output differential and if the index is greater or equal to a predetermined index value then annunciate an error otherwise calculate the glucose value from the output signal and annunciate the glucose value.

2. The system of claim 1, in which the predetermined time window comprises from about 1 second after a start of a test sequence to about 8 seconds after the start of the test sequence.

3. The system of claim 1, in which the predetermined index value comprises about 5 and the predetermined threshold comprises about 300.

4. The system of claim 1, in which the predetermined time window comprises from about 2 second after a start of a test sequence to about 8 seconds after the start of the test sequence.

5. The system of claim 1, in which the predetermined index value comprises about 5 and the predetermined threshold comprises about 150.

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 a fluid sample proximate the at least two electrodes of the biosensor;

applying an input signal to the fluid sample to cause a transformation of glucose into an enzymatic by-product;

measuring output signal transient from the fluid sample over a predetermined time window from the start of the test sequence, the measuring including sampling an output signal from at least one electrode during the electrochemical reaction over a series of time intervals to obtain a magnitude of the output signal for each time interval;

determining an output differential as a difference in the respective magnitudes of the

output signal for at least two consecutive time intervals within the predetermined time window during the test measurement sequence;

if the output differential is greater than zero then setting an index value as equal to the sum of both a previous value of the index and the output differential, otherwise if the index is greater than a predetermined index value then annunciating an error, otherwise calculating a glucose value of the fluid sample and annunciating the glucose value.

7. The method of claim 6, in which the calculating of the glucose value comprises measuring a magnitude of the output signal proximate a predetermined time interval from the start of the test sequence and utilizing an equation of the form:

8. The method of claim 6, in which the predetermined time window comprises from about 1 second after a start of a test sequence to about 8 seconds after the start of the test sequence.

9. The method of claim 6, in which the predetermined index value comprises about 2 microamps and the predetermined threshold comprises about 0.5 microamps.

10. The method of claim 6, in which the predetermined time window comprises from about 2 seconds after a start of a test sequence to about 8 seconds after the start of the test sequence.