System and method for measuring an analyte in a sample
View Patent ↗Described are methods and systems to calculate an analyte concentration of a sample are provided without temperature compensation to a glucose concentration calculation when a measured or sampled current is taken at or before a change in a first voltage to a second voltage that are applied to a test trip with electrodes in a test cell.
1. A method of determining blood glucose concentration with a glucose measurement system that includes a test strip and test meter, the test meter having a microcontroller configured to apply a plurality of test voltages to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip, the method comprising:
inserting the test strip into a strip port connector of the test meter to connect at least two electrodes of the test strip to a strip measurement circuit;
initiating a test sequence after deposition of a sample;
applying a first voltage to the at least two electrodes of the test strip for a first time interval from the initiation of test sequence to cause a transformation of analytes in the sample;
switching the first voltage to a second voltage different than the first voltage;
changing the second voltage to a third voltage different from the first or second voltages;
measuring a first current output of a current transient from the electrodes during an interval for the switching of the first voltage to the second voltage but prior to a complete changeover to the second voltage;
measuring a second current output of the current transient from the electrodes after the changing from the second voltage to the third voltage;
estimating a steady state current output of the current transient after the third voltage is maintained at the electrodes; and
calculating a blood glucose concentration based on the first, second and steady state current output of the current transient without compensation for temperature on the glucose concentration.
2. A method of determining blood glucose concentration with a glucose measurement system that includes a test strip and test meter, the test meter having a microcontroller configured to apply a plurality of test voltages to the test strip and measure a current transient output resulting from an electrochemical reaction in a test chamber of the test strip, the method comprising:
inserting the test strip into a strip port connector of the test meter to connect at least two electrodes of the test strip to a strip measurement circuit;
initiating a test sequence after deposition of a sample;
applying a first voltage to the at least two electrodes of the test strip for a first time interval from the initiation of test sequence to cause a transformation of analytes in the sample;
switching the first voltage to a second voltage different than the first voltage;
changing the second voltage to a third voltage different from the first or second voltages;
measuring a first current output of a current transient from the electrodes during an interval for the switching of the first voltage to the second voltage but prior to a complete changeover to the second voltage;
measuring a second current output of the current transient from the electrodes after the changing from the second voltage to the third voltage;
estimating a steady state current output of the current transient after the third voltage is maintained at the electrodes; and
calculating a blood glucose concentration based on the first, second and steady state current output of the current transient without compensation for temperature on the glucose concentration with an equation of the form:
G
1
=
(
i
r
i
l
)
p
(
a
i
2
CORR
-
zgr
)
;
where: G 1 is proportional to a glucose concentration;
i
r
=
∑
t
=
4.4
t
=
5
i
(
t
)
;
i
l
=
∑
t
=
1.4
t
=
4
i
(
t
)
;
i
2
(
Corr
)
=
(
i
4.1
+
b
i
5
-
c
i
1.0
i
4.1
+
b
i
5
)
i
r
where:
a, b, c, p, zgr comprise manufacturing parameters;
wherein a is approximately 0.192; b is approximately 0.678; p is approximately 0.523; zgr is approximately 2; and scaling or correction factor c is approximately about 20;
i 4.1 is the current measured at about 4.1 seconds after initiation of test sequence;
i 5 is the current measured at about 5 seconds after initiation of test sequence;
i 1.0 is the current measured at about 1 second after initiation of test sequence.
3. The method of any one of claim 1 or claim 2 , in which the measuring of the first current output comprises measuring a current output of the at least two electrodes at about 1 second after initiation of test sequence.
4. The method of any one of claim 1 or claim 2 , in which the measuring of the second current output comprises measuring a current output of the at least two electrodes at about 4.1 seconds after initiation of test sequence.
5. The method any one of claim 1 or claim 2 , in which the estimating of the steady state current output comprises measuring a current output of the at least two electrodes at about 5 seconds after initiation of test sequence.
6. A blood glucose measurement system comprising:
an analyte test strip including:
a substrate having a reagent disposed thereon;
at least two electrodes proximate the reagent in test chamber;
an analyte meter including:
a strip port connector disposed to connect to the two electrodes;
a power supply; and
a microcontroller electrically coupled to the strip port connector and the power supply so that, when the test strip is inserted into the strip port connector and a blood sample is deposited in the test chamber for chemical transformations of glucose in the blood sample, a glucose concentration of the blood sample is determined by the microcontroller without additional temperature compensation for the glucose concentration
wherein the microcontroller is programmed to deliver a plurality of voltages to the electrodes and calculate the glucose concentration from a current transient output from the electrodes with an equation of the form:
G
1
=
(
i
r
i
l
)
p
(
a
i
2
CORR
-
zgr
)
;
where: G 1 is proportional to a glucose concentration;
i
r
=
∑
t
=
4.4
t
=
5
i
(
t
)
;
i
l
=
∑
t
=
1.4
t
=
4
i
(
t
)
;
i
2
(
Corr
)
=
(
i
4.1
+
b
i
5
-
c
i
1.0
i
4.1
+
b
i
5
)
i
r
wherein a, b, c, p, zgr comprise manufacturing parameters; a is approximately 0.192; b is approximately 0.678; p is approximately 0.523; zgr is approximately 2; and scaling or correction factor c is approximately about 20;
i 4.1 is the current measured at about 4.1 seconds after initiation of test sequence;
i 5 is the current measured at about 5 seconds after initiation of test sequence; and
i 1.0 is the current measured at about 1 second after initiation of test sequence of blood sample.
7. A blood glucose measurement system to measure a glucose concentration in physiological fluid of a user, the system comprising: a test strip including an electrochemical cell having at least a working electrode and a counter electrode and a reagent layer having a mediator in a test area, the electrodes being connected to corresponding contact pads; and an analyte meter having a microprocessor and a test circuit in connection with a test strip port that electrically connects the contact pads of the test strip so that the meter is configured to apply first, second, and third voltages after deposition of physiological fluid on the electrodes and determine a glucose concentration from measuring a first current output of a current transient from the electrodes during an interval for switching of the first voltage to the second voltage but prior to a complete changeover to the second voltage; measuring a second current output of the current transient from the electrodes after changing from the second voltage to the third voltage; and estimating a steady state current output of the current transient after the third voltage is maintained at the electrodes without any temperature compensation for the glucose concentration.
8. The blood glucose measurement system of claim 7 , wherein the first measured current output comprises a current measured prior to 1.1 seconds from the deposition of the physiological sample.
9. The blood glucose measurement system of claim 7 , in which the meter is programmed with an equation of the form:
G
1
=
(
i
r
i
l
)
p
(
a
i
2
CORR
-
zgr
)
;
where: G 1 is proportional to a glucose concentration;
i
r
=
∑
t
=
4.4
t
=
5
i
(
t
)
;
i
l
=
∑
t
=
1.4
t
=
4
i
(
t
)
;
i
2
(
Corr
)
=
(
i
4.1
+
b
i
5
-
c
i
1.0
i
4.1
+
b
i
5
)
i
r
wherein a, b, c, p, zgr comprise manufacturing parameters; a is approximately 0.192; b is approximately 0.678; p is approximately 0.523; zgr is approximately 2 and scaling or correction factor c is approximately about 20;
i 4.1 is the current measured at about 4.1 seconds after initiation of test sequence;
i 5 is the current measured at about 5 seconds after initiation of test sequence; and
i 1.0 is the current measured at about 1 second after initiation of test sequence of blood sample.