Real time self-adjusting calibration algorithm
First Claim
1. A method of calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the method comprising the steps of:
- obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
confirming a sensor failure or recognizing a change in sensor sensitivity by comparing the current calibration factor with an estimated value for the current calibration factor to determine whether the current calibration factor was unexpected, wherein the estimated value for the current calibration factor is determined from the calibration formula and a past calibration factor; and
confirming the sensor failure when at least two unexpected calibration factors are received in succession without supporting each other.
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Accused Products
Abstract
A method of calibrating glucose monitor data includes collecting the glucose monitor data over a period of time at predetermined intervals. It also includes obtaining at least two reference glucose values from a reference source that temporally correspond with the glucose monitor data obtained at the predetermined intervals. Also included is calculating the calibration characteristics using the reference glucose values and the corresponding glucose monitor data to regress the obtained glucose monitor data. And calibrating the obtained glucose monitor data using the calibration characteristics is included. In preferred embodiments, the reference source is a blood glucose meter, and the at least two reference glucose values are obtained from blood tests. In additional embodiments, the calculation of the calibration characteristics is obtained using linear regression and in particular embodiments, least squares linear regression. Alternatively, the calculation of the calibration characteristics is obtained using non-linear regression.
1268 Citations
39 Claims
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1. A method of calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the method comprising the steps of:
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obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
confirming a sensor failure or recognizing a change in sensor sensitivity by comparing the current calibration factor with an estimated value for the current calibration factor to determine whether the current calibration factor was unexpected, wherein the estimated value for the current calibration factor is determined from the calibration formula and a past calibration factor; and
confirming the sensor failure when at least two unexpected calibration factors are received in succession without supporting each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the method comprising the steps of:
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obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
confirming a sensor failure or recognizing a change in sensor sensitivity by comparing the current calibration factor with an estimated value determined from the calibration formula and a past calibration factor;
recognizing a change in sensor sensitivity when an unexpected past calibration factor is supported by a subsequent current calibration factor in succession;
restarting the calibration formula calculation when a change in sensor sensitivity is recognized by creating an artificial calibration reference value; and
formulating the calibration formula using the artificial calibration reference value, a past calibration reference value and a current calibration reference value.
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13. An apparatus for calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the apparatus comprising:
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means for obtaining a calibration reference value for the sensor;
means for calculating a current calibration factor based on the calibration reference value and a current sensor data point;
means for identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
means for confirming a sensor failure or recognizing a change in sensor sensitivity by using a means for comparing the current calibration factor with an estimated value for the current calibration factor to determine whether the current calibration factor was unexpected, wherein the estimated value for the current calibration factor is determined from the calibration formula and a past calibration factor; and
means for confirming the sensor failure when at least two unexpected calibration factors are received in succession without supporting each other. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An apparatus for calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the apparatus comprising:
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means for obtaining a calibration reference value for the sensor;
means for calculating a current calibration factor based on the calibration reference value and a current sensor data point;
means for identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
means for confirming a sensor failure or recognizing a change in sensor sensitivity by using a means for comparing the current calibration factor with an estimated value determined from the calibration formula and a past calibration factor;
means for recognizing a change in sensor sensitivity when an unexpected past calibration factor is supported by a subsequent current calibration factor in succession;
restarting the calibration formula calculation when a change in sensor sensitivity is recognized by means for creating an artificial calibration reference value; and
means for formulating the calibration formula using the artificial calibration reference value, a past calibration reference value and a current calibration reference value.
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25. An article of manufacture containing code for calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, comprising a computer usable media including at least one embedded computer program that is capable of causing at least one computer to perform:
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obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
confirming a sensor failure or recognizing a change in sensor sensitivity by comparing the current calibration factor with an estimated value for the current calibration factor to determine whether the current calibration factor was unexpected, wherein the estimated value for the current calibration factor is determined from the calibration formula and a past calibration factor; and
confirming the sensor failure when at least two unexpected calibration factors are received in succession without supporting each other. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. An article of manufacture containing code for calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, comprising a computer usable media including at least one embedded computer program that is capable of causing at least one computer to perform:
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obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying either a possible error or change in sensitivity in the sensor from the current calibration factor; and
confirming a sensor failure or recognizing a change in sensor sensitivity by comparing the current calibration factor with an estimated value determined from the calibration formula and a east calibration factor;
recognizing a change in sensor sensitivity when an unexpected past calibration factor is supported by a subsequent current calibration factor in succession;
restarting the calibration formula calculation when a change in sensor sensitivity is recognized by creating an artificial calibration reference value; and
formulating the calibration formula using the artificial calibration reference value, a past calibration reference value and a current calibration reference value.
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37. A method of calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the method comprising the steps of:
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obtaining a calibration reference value for the sensor;
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
identifying a possible error from the current calibration factor;
updating the calibration formula with the calibration reference value if no error is identified; and
interpreting the collected sensor data using the updated calibration formula;
wherein the calibration formula is a modified regression method which weights past calibrations based on how recent the calibration was performed. - View Dependent Claims (38)
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39. A method of calibrating sensor data collected from a sensor, wherein a calibration formula based on past calibrations is used to interpret the sensor data, the method comprising the steps of:
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obtaining a calibration reference value for the sensor; and
calculating a current calibration factor based on the calibration reference value and a current sensor data point;
wherein the current sensor data point is obtained by the steps of;
sampling characteristic sensor data;
deriving interval values by applying clipping limits and averaging the post-clipped sampled characteristic sensor data over a predetermined interval rate; and
deriving at least one current sensor data point by averaging the derived interval values at a predetermined memory storage rate.
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Specification