Method for Determination of Analyte Concentrations and Related Apparatus

• US 20100126881A1
• Filed: 01/12/2010
• Published: 05/27/2010
• Est. Priority Date: 04/15/2005
• Status: Active Grant

• Current Assignee: Agamatrix Incorporated (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Original Assignee: Agamatrix Incorporated (AgaMatrix Holdings LLC d/b/a WaveForm Diabetes)
• Inventors: Diamond, Steven, Harding, Ian, Wei, Baoguo, Iyengar, Sridhar G.
• Granted Patent: US 8,016,997 B2
• Time in Patent Office: Days
• US Class Current: 205/775
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• 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 27/4161 measuring the voltage and using a constant current supply, e.g. chronopotentiometry
• CPC Class Codes: G01N 27/4166 measuring a particular property of an electrolyte
• CPC Class Codes: G01N 33/48707 by electrical means G01N33/49, G01N33/493 take precedence

Abstract

A method is provided for determining analyte concentrations, for example glucose concentrations, that utilizes a dynamic determination of the appropriate time for making a glucose measurement, for example when a current versus time curve substantially conforms to a Cottrell decay, or when the current is established in a plateau region. Dynamic determination of the time to take the measurement allows each strip to operate in the shortest appropriate time frame, thereby avoiding using an average measurement time that may be longer than necessary for some strips and too short for others.

Claims

1-18. -18. (canceled)

19. A method for determining the time of sample application, and triggering the start of an electrochemical assay conducted in an electrochemical test cell comprising a working and a counter electrode, comprising the steps of:

(a) applying a pulsed voltage, Vw, to the working electrode while holding the voltage, Vc, of the counter electrode constant commencing at a time prior to the introduction of sample to the electrochemical test cell, said pulsed voltage having a pulse frequency;

(b) monitoring the electrochemical test cell for the passage of current between the electrodes, said passage of current being in the form of current spikes having a frequency equal to the pulse frequency and being indicative of the addition of a sample to the electrochemical test cell, and

(c) triggering the start of the electrochemical assay when a plurality of current spikes have been observed, and when said plurality is least a pre-determined fraction of the pre-determined number of consecutive current spikes.

20. The method of claim 19, wherein the pulsed voltage is established using a low pass filter on Vw.

21. The method of claim 19, wherein the pulse frequency is from 20 to 50 Hz.

22. The method of claim 21, wherein the pulse frequency is from 33 to 40 Hz.

23. The method of claim 19, wherein the predetermined fraction is equal to or greater than two-thirds.

24. The method of claim 23, wherein the predetermined number of consecutive spikes is greater than 4.

25. The method of claim 23, wherein the predetermined number of consecutive spikes is 6.

26. The method of claim 23, wherein the predetermined fraction is equal to or greater than three-fourths.

27. A method for detecting an error condition in an electrochemical determination of an analyte in a sample applied to an electrochemical test strip disposed in an analyte detection apparatus, comprising the steps of:

(a) introducing a sample to be evaluated into an electrochemical test strip having working and counter electrodes;

(b) applying a potential between the electrodes sufficient to generate a diffusion-limited current when analyte is present in the sample;

(c) dynamically determining a time, t_peak, as the time when diffusion limiting current at the counter electrode is established;

(d) comparing the determined value of t_peak to a predetermined range, and returning an error message when the determined value falls outside of the range.