Devices using gated voltammetry methods

Patent metadata

Field	Value
Publication number	US-9835582-B2
Application number	US-201514796544-A
Country	US
Kind code	B2
Filing date	Jul 10, 2015
Priority date	Sep 30, 2005
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A sensor system, device, and methods for determining the concentration of an analyte in a sample is described. Gated voltammetric pulse sequences including multiple duty cycles of sequential excitations and relaxations may provide a shorter analysis time and/or improve the accuracy and/or precision of the analysis. The disclosed pulse sequences may reduce analysis errors arising from the hematocrit effect, variance in cap-gap volumes, non-steady-state conditions, mediator background, a single set of calibration constants, under-fill, and changes in the active ionizing agent content of the sensor strip.

First claim

The invention claimed is:

1. A handheld measuring device for signaling a user to add additional sample to a sensor strip received by the handheld measuring device, the sensor strip including at least two electrodes, the handheld measuring device comprising:
at least two contacts each electrically coupled to respective ones of the at least two electrodes responsive to the sensor strip being received by the handheld measuring device; and
electrical circuitry including a processor in electrical communication with an electric charger and the at least two contacts, where the processor is programmed to:
apply a gated voltammetric pulse sequence from the electric charger to the sample through the at least two electrodes of the sensor strip, the pulse sequence having at least two duty cycles,
wherein each of the at least two duty cycles includes an excitation and a relaxation, and
wherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima;
determine if the sensor strip is under-filled by comparing at least one current value recorded from the gated voltammetric pulse sequence including the at least two duty cycles to a pre-selected value; and
signal the user to add additional sample to the sensor strip if the sensor strip is under-filled.

2. The device of claim 1 , wherein the processor determines if the sensor strip is under-filled in less than five seconds.

3. The device of claim 1 , wherein the at least one current value is lower than the pre-selected value if the sensor strip is under-filled.

4. The device of claim 1 , wherein the gated voltammetric pulse sequence comprises at least three duty cycles within 90 seconds or at least three duty cycles within 5 seconds.

5. The device of claim 1 , wherein the at least two electrodes are a counter electrode and a working electrode and the working electrode includes a diffusion barrier layer.

6. The device of claim 1 , wherein the potential varied with time is varied linearly at a rate of at least 2 mV/sec.

7. The device of claim 6 , wherein the excitations are selected from the group consisting of linear, cyclic, acyclic, and combinations thereof.

8. The device of claim 1 , wherein the excitations are acyclic and substantially exclude a reverse oxidation peak or a reverse reduction peak of a measurable species responsive to a concentration of an analyte in the sample.

9. The device of claim 1 , wherein
the excitations are acyclic and terminate before initiation of a reverse current peak,
the excitations are acyclic and substantially exclude forward and reverse oxidation and reduction peaks of a measurable species responsive to a concentration of an analyte in the sample, or
the excitations are acyclic and are substantially within a diffusion limited current region of a redox pair.

10. A handheld measuring device for determining a concentration of an analyte in a sample, the handheld measuring device comprising:
at least two contacts; and
electrical circuitry including a processor in electrical communication with an electric charger and the at least two contacts, where the processor is programmed to carry out a voltammetric method comprising:
applying a pulse sequence from the electric charger to the sample via the at least two contacts, the pulse sequence comprising at least two duty cycles having excitation/relaxation time ratios from 0.3 to 0.2, wherein each of the at least two duty cycles includes a relaxation, and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima;
measuring resulting currents from the at least two duty cycles; and
determining the concentration of the analyte in the sample from the resulting currents.

11. The device of claim 10 , wherein the concentration of the analyte determined from the voltammetric method is more accurate than a concentration of the analyte in the sample determined from another voltammetric method other than the voltammetric method wherein the excitation/relaxation time ratio of the pulse sequence is greater than 0.3.

12. The device of claim 10 , wherein the determining is performed in less than five seconds.

13. The device of claim 10 , wherein the pulse sequence comprises at least three duty cycles within 90 seconds or at least three duty cycles within 5 seconds.

14. The device of claim 10 , wherein each of the at least two duty cycles includes an excitation, and wherein each of the excitations includes a potential varied linearly at a rate of at least 2 mV/sec.

15. The device of claim 14 , wherein each of the excitations is selected from the group consisting of linear, cyclic, acyclic, and combinations thereof.

16. The device of claim 10 , wherein each of the at least two duty cycles includes an excitation, and wherein each of the excitations is acyclic and substantially exclude a reverse oxidation peak or a reverse reduction peak of a measurable species responsive to the concentration of the analyte in the sample.

17. The device of claim 10 , wherein each of the at least two duty cycles includes an excitation, and wherein
the excitations are acyclic and terminate before initiation of a reverse current peak,
the excitations are acyclic and substantially exclude forward and reverse oxidation and reduction peaks of a measurable species responsive to the concentration of the analyte in the sample, or
the excitations are acyclic and are substantially within a diffusion limited current region of a redox pair.

18. A handheld measuring device for determining a hematocrit concentration of a blood sample, the handheld measuring device comprising:
at least two contacts; and
electrical circuitry including a processor in electrical communication with an electric charger and the at least two contacts, where the processor is programmed to carry out a voltammetric method comprising:
applying a gated voltammetric pulse sequence from the electric charger to the blood sample via the at least two contacts, the pulse sequence having at least two duty cycles,
wherein each of the at least two duty cycles includes an excitation and a relaxation, and
wherein the excitations of the at least two duty cycles include a potential varied with time and the relaxations of the at least two duty cycles include a current reduction to at least one-half the current flow at the excitation maxima;
measuring resulting currents from at least one of the excitations;
applying a semi-integral data treatment to the resulting currents, the semi-integral data treatment providing a peak portion; and
quantitatively relating the peak portion to the hematocrit concentration of the blood sample.

19. The device of claim 18 , wherein the excitations are acyclic and substantially exclude a reverse oxidation peak or a reverse reduction peak of a measurable species responsive to a concentration of an analyte in the blood sample.

20. The device of claim 18 , wherein
the excitations are acyclic and terminate before initiation of a reverse current peak,
the excitations are acyclic and substantially exclude forward and reverse oxidation and reduction peaks of a measurable species responsive to a concentration of an analyte in the sample, or
the excitations are acyclic and are substantially within a diffusion limited current region of a redox pair.

21. A handheld measuring devic

Assignees

• Ascensia Diabetes Care Holdings Ag

Inventors

• Wu Huan-Ping

Classifications

• G01N33/5438

  Electrodes · CPC title

• A61B5/14532 Primary

  for measuring glucose, e.g. by tissue impedance measurement · CPC title

• A61B5/1486

  using enzyme electrodes, e.g. with immobilised oxidase · CPC title

• G01N27/3273

  Devices therefor, e.g. test element readers, circuitry (details not specific to biochemical electrodes G01N33/4875) · CPC title

• C12Q1/001

  Enzyme electrodes · CPC title