Signal processing for measurement of physiological analysis
First Claim
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1. A method for measuring an analyte present in a biological system, said method comprising:
- (a) transdermally extracting the analyte from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system;
(b) obtaining a raw signal from the extracted analyte, wherein said raw signal is related to analyte concentration;
(c) subjecting the raw signal obtained in step (b) to a conversion step in order to convert said raw signal to an initial signal output which is indicative of the amount of analyte extracted by the sampling system;
(d) performing a calibration step which converts the initial signal output obtained in step (c) to a measurement value indicative of the concentration of analyte present in the biological system at the time of extraction; and
(e) repeating steps (a)-(c) at least once to obtain a plurality of measurement values, wherein the sampling system is maintained in operative contact with the skin or mucosal surface of said biological system to provide for analyte measurement.
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Abstract
A method is provided for continually or continuously measuring the concentration of target chemical analytes present in a biological system, and processing analyte-specific signals to obtain a measurement value that is closely correlated with the concentration of the target chemical analyte in the biological system. One important application of the invention involves a method for signal processing in a system for monitoring blood glucose values.
1425 Citations
44 Claims
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1. A method for measuring an analyte present in a biological system, said method comprising:
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(a) transdermally extracting the analyte from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system;
(b) obtaining a raw signal from the extracted analyte, wherein said raw signal is related to analyte concentration;
(c) subjecting the raw signal obtained in step (b) to a conversion step in order to convert said raw signal to an initial signal output which is indicative of the amount of analyte extracted by the sampling system;
(d) performing a calibration step which converts the initial signal output obtained in step (c) to a measurement value indicative of the concentration of analyte present in the biological system at the time of extraction; and
(e) repeating steps (a)-(c) at least once to obtain a plurality of measurement values, wherein the sampling system is maintained in operative contact with the skin or mucosal surface of said biological system to provide for analyte measurement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 44)
wherein;
BGcal is the true blood glucose at the calibration point;
Ecal is the analyte signal at calibration;
(tcal) is the elapsed time of the calibration point;
(EGt) is the estimated blood glucose concentration at time t;
(Et) is the analyte signal at time t;
(OS) is the constant offset term which accounts for a non-zero signal at an estimated zero blood glucose concentration;
(γ
) is a time-dependent correction term for signal decline;
(α
) is a time-dependent correction term for signal decline; and
(t) is the elapsed time.
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28. The method of claim 27, wherein a time segmentation is performed as follows:
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if t23<
tcal
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29. The method of claim 1, wherein the conversion step further entails using a temperature correction function to correct for changes in the biological system and/or changes in the sensing device.
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30. The method of claim 29, wherein the changes in the biological system comprise a change in temperature.
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31. The method of claim 29, wherein the conversion step entails correcting for temperature changes occurring between a measurement of background signal in the sensing device and measurement of a raw signal in step (b), and during the measurement of the raw signal.
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32. The method of claim 31, wherein the temperature correction uses an Arrhenius correction function.
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33. The method of claim 31, wherein the temperature correction uses an integral average temperature correction function obtained from a measurement cycle to correct for temperature at subsequent time points.
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34. The method of claim 29, wherein the conversion step entails correcting for temperature differences between multiple signals obtained from the sensing device.
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35. The method of claim 2, wherein said biological system includes skin, and said extracting of analyte from the biological system into a reservoir further comprises enhancement of skin permeability by pricking the skin with micro-needles.
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44. The method of claim 25, wherein the compensating is carried out using the following function:
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36. A monitoring system for measuring an analyte present in a biological system, said system comprising, in operative combination:
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(a) sampling means for extracting the analyte from the biological system, wherein said sampling means is adapted for extracting the analyte across a skin or mucosal surface of said biological system;
(b) sensing means in operative contact with the analyte extracted by the sampling means, wherein said sensing means obtains a raw signal from the extracted analyte and said raw signal is specifically related to the analyte; and
(c) microprocessor means in operative communication with the sensing means, wherein said microprocessor means (i) subjects the raw signal to a conversion step to convert said raw signal to an initial signal output which is indicative of the amount of analyte extracted by the sampling means, and (ii) performs a calibration step which correlates said initial signal output with a measurement value indicative of the concentration of analyte present in the biological system at the time of extraction. - View Dependent Claims (37, 38, 39, 40, 41, 42)
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43. A monitoring system for measuring an analyte present in a biological system, said system comprising,
one or more microprocessors capable of (i) subjecting a raw signal, obtained from an extracted analyte, to a conversion step to convert said raw signal to an initial signal output which is indicative of an amount or concentration of the extracted analyte, and (ii) performing a calibration step which correlates said initial signal output with a measurement value indicative of the amount or concentration of analyte present in the biological system at the time of analyte extraction.
Specification