Method and Apparatus for Implementing Threshold Based Correction Functions for Biosensors
A biosensor system, method and apparatus are provided for implementing threshold based correction functions for biosensors. A primary measurement of an analyte value is obtained. A secondary measurement of a secondary effect is obtained and is compared with a threshold value. A correction function is identified responsive to the compared values. The correction function is applied to the primary measurement of the analyte value to provide a corrected analyte value. The correction method uses correction curves that are provided to correct for an interference effect. The correction curves can be linear or non-linear. The correction method provides different correction functions above and below the threshold value. The correction functions may be dependent or independent of the primary measurement that is being corrected. The correction functions may be either linear or nonlinear.
1 . A method for implementing threshold based correction functions for a biosensor comprising the steps of:
applying a sample to the biosensor and obtaining a primary measurement of an analyte value;
obtaining a secondary measurement of a secondary effect;
comparing said secondary measurement of the secondary effect with a threshold value;
responsive to said compared values, identifying a correction function; and
applying said identified correction function to said primary measurement to provide a corrected analyte value.
2 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the step responsive to said compared values, of identifying a correction function includes the steps of identifying said secondary measurement of the secondary effect less than or equal to said threshold value, identifying a first coefficient A, said first coefficient A to control magnitude of said correction function.
3 . A method for implementing threshold based correction functions for a biosensor as recited in claim 2 further includes the steps of calculating said correction function represented by
C n =F*T+A* ( T c −T ) +H,
where T represents said secondary measurement of the secondary effect, T c represents said threshold value; and F, H are predefined coefficients.
4 . A method for implementing threshold based correction functions for a biosensor as recited in claim 3 wherein the step of applying said identified correction function to said primary measurement to provide a corrected analyte value further includes the steps of calculating said corrected analyte value represented by
Gc=Gn/Cn,
where Gn represent said primary measurement of said analyte value.
5 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the step responsive to said compared values, of identifying a correction function includes the steps of identifying said secondary measurement of the secondary effect greater than said threshold value, identifying a coefficient I, said coefficient I being used to control magnitude of said correction function.
6 . A method for implementing threshold based correction functions for a biosensor as recited in claim 5 further includes the steps of calculating said correction function represented by
C n =F*T+I* ( T−T c ) +H,
where T represents said secondary measurement of the secondary effect, T c represents said threshold value; and F, H are predefined coefficients.
7 . A method for implementing threshold based correction functions for a biosensor as recited in claim 6 wherein the step of applying said identified correction function to said primary measurement to provide a corrected analyte value further includes the steps of calculating said corrected analyte value represented by
Gc=Gn/Cn,
where Gn represent said primary measurement of said analyte value.
8 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the step of responsive to said compared values, identifying a correction function includes the steps of storing predefined correction curves; said predefined correction curves being provided to correct for an interference effect.
9 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the step of responsive to said compared values, identifying a correction function includes the steps responsive to said secondary measurement of the secondary effect being less than or equal to said threshold value of identifying a first coefficient A and identifying said correction function responsive to said identified first coefficient A.
10 . A method for implementing threshold based correction functions for a biosensor as recited in claim 9 wherein the step of responsive to said compared values, identifying a correction function includes the steps responsive to said secondary measurement of the secondary effect being greater than said threshold value of identifying a second coefficient I and identifying said correction function responsive to said identified second coefficient I.
11 . A method for implementing threshold based correction functions for a biosensor as recited in claim 10 wherein the steps of identifying said first coefficient A and identifying a second coefficient I include the steps of providing stored correction curves; said correction curves representing characteristics of said secondary measurement of the secondary effect.
12 . A method for implementing threshold based correction functions for a biosensor as recited in claim 10 wherein the steps of identifying said correction function responsive to said identified second coefficient A and identifying said correction function responsive to said identified second coefficient I includes the steps of identifying a linear function for said correction function.
13 . A method for implementing threshold based correction functions for a biosensor as recited in claim 10 wherein the steps of identifying said correction function responsive to said identified second coefficient A and identifying said correction function responsive to said identified second coefficient I includes the steps of identifying a nonlinear function for said correction function.
14 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the steps of identifying said correction function includes the steps of identifying said correction function using at least one coefficient value; said at least one coefficient value being dependent upon said primary measurement of said analyte value.
15 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the steps of identifying said correction function includes the steps of identifying said correction function using at least one coefficient value; said at least one coefficient value being a predefined value independent of said primary measurement of said analyte value.
16 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the step of obtaining a secondary measurement of a secondary effect include the step of obtaining a temperature measurement.
17 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the analyte is glucose and wherein step of obtaining a secondary measurement of a secondary effect include the step of obtaining a hemoglobin measurement.
18 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the analyte is glucose and wherein step of obtaining a secondary measurement of a secondary effect include the step of obtaining a measurement indicating a concentration of hematocrit.
19 . A method for implementing threshold based correction functions for a biosensor as recited in claim 1 wherein the analyte is glucose and wherein step of obtaining a secondary measurement of a secondary effect include the step of obtaining a measurement indicating a concentration of hematocrit and obtaining a temperature measurement.
20 . Apparatus for implementing threshold based correction functions comprising:
a biosensor for receiving a sample;
a processor coupled to said biosensor; said processor responsive to said biosensor for receiving the sample for obtaining a primary measurement of an analyte value;
said processor for obtaining a secondary measurement of a secondary effect;
said processor for comparing said secondary measurement of the secondary effect with a threshold value;
said processor responsive to said compared values, for identifying a correction function; and
said processor for applying said identified correction function to said primary measurement to provide a corrected analyte value
21 . Apparatus for implementing threshold based correction functions as recited in claim 20 includes stored correction curves used by said processor for identifying said correction function; said correction curves representing characteristics of said secondary measurement of the secondary effect.
22 . Apparatus for implementing threshold based correction functions as recited in claim 20 wherein said processor is responsive to identifying said secondary measurement of the secondary effect less than or equal to said threshold value, for identifying a first coefficient A, said first coefficient A being used to control magnitude of said correction function.
23 . Apparatus for implementing threshold based correction functions as recited in claim 22 wherein said processor is responsive to identifying said secondary measurement of the secondary effect greater than said threshold value, for identifying a second coefficient I, said second coefficient I being used to control magnitude of said correction function.