Systems and methods for improved stability of electrochemical sensors
Methods for determining a concentration of an analyte in a sample, and the devices and systems used in conjunction with the same, are provided herein. In one exemplary embodiment of a method for determining a concentration of an analyte in a sample, a sample including an analyte is provided in a sample analyzing device having a working and a counter electrode. An electric potential is applied between the electrodes and a measurement of a parameter correlating to changes in a physical property of the sample analyzing device is calculated. A concentration of the analyte in view of the parameter correlating to a change in the physical property can then be determined. Systems and devices that take advantage of the parameter correlating to changes in a physical property to make analyte concentration determinations are also provided.
1. An electrochemical system, comprising:
an electrochemical cell having a first electrode and a second electrode;
a meter including a control unit connected to the electrochemical cell so that the control unit is configured to apply at least one potential between the first electrode and the second electrode of the electrochemical cell to determine an analyte concentration of an applied sample; and
the control unit configured to determine a measurement of capacitance correlating to an age or storage condition of the electrochemical cell and further configured to use said capacitance measurement to calculate a corrected concentration of the analyte in the sample.
2. The electrochemical system of claim 1 , wherein said storage condition comprises a storage temperature and a storage time.
3. The electrochemical system of claim 1 , wherein the sample comprises blood.
4. The electrochemical system of claim 3 , wherein the blood comprises whole blood.
5. The electrochemical system of claim 1 , in which the control unit is configured to store a predetermined analyte concentration and a capacitance threshold, in which the control unit is further configured to measure a capacitance of the electrochemical cell and determine a correction factor based on the measured capacitance to correct for the age or storage condition of the electrochemical cell.
6. The electrochemical system of claim 5 , in which the control unit is configured to set the correction factor to zero if the measured capacitance is not less than the capacitance threshold and the analyte concentration measured by the meter is not greater than a stored analyte concentration threshold.
7. The electrochemical system of claim 5 , in which the control unit is configured to calculate the correction factor using a capacitance correction function if the measured capacitance is less than the capacitance threshold and the analyte concentration measured by the meter is greater than a stored analyte concentration threshold.
8. The electrochemical system of claim 7 , wherein the capacitance correction function is C c =K c (C 1 −C) in which C c is the correction factor, K c is a constant, C is the measured capacitance, and C 1 is the predetermined capacitance threshold.
9. The electrochemical system of claim 8 , in which a capacitance corrected analyte concentration is determined by the control unit by dividing the correction factor by one hundred, adding one and then multiplying a resulting value by the measured analyte concentration.
10. An electrochemical system, comprising:
(a) a test strip including electrical contacts configured to mate with a test meter and an electrochemical cell comprising:
(i) a first electrode and a second electrode in a spaced apart relationship; and
(ii) a reagent; and
(b) the test meter including a processor configured to receive current data from the test strip upon application of voltages to the test strip, and further configured to determine a capacitance corrected glucose concentration based on a calculated glucose concentration and a measured capacitance wherein the measured capacitance correlates to at least one of an age or storage condition of the test strip, the processor being configured to determine a correction factor based on the measured capacitance to correct for the age or storage condition of the electrochemical cell.
11. The electrochemical system of claim 10 , wherein said storage condition comprises a storage temperature and a storage time.
12. The electrochemical system of claim 10 , in which the processor is configured to set the correction factor to zero if the measured capacitance is not less than a predetermined capacitance threshold and an uncorrected glucose concentration as measured by the test meter is not greater than a predetermined glucose concentration threshold.
13. The electrochemical system of claim 10 , in which the processor is configured to calculate the correction factor using a capacitance correction function if the measured capacitance is less than a stored capacitance threshold and an uncorrected glucose concentration as measured by the test meter is greater than a stored glucose concentration threshold.
14. The electrochemical system of claim 13 , wherein the capacitance correction function is C c =K c (C 1 −C) in which C c is the correction factor, K c is a constant, C is the measured capacitance and C 1 is the predetermined capacitance threshold.
15. The electrochemical system of claim 14 , in which the processor is further configured to determine the capacitance corrected glucose concentration by dividing the correction factor C c by one hundred, adding one and then multiplying a resulting value by the measured glucose concentration.