Monitoring of physiological analytes
First Claim
1. A method for measuring the concentration of an analyte present in a biological system, said method comprising a measurement cycle which comprises an extraction step in which a sample containing the analyte is transdermally extracted from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system, and a sensing step in which the extracted sample is contacted with sensor means to obtain a measurement signal that is related to analyte concentration, wherein said measurement cycle further comprises a process for selectively favoring-analyte-specific signal components over signal components due to interfering species, said process selected from the group consisting of (a) a differential signal process which subtracts non-analyte signal components from the measurement signal, (b) a delay step which is performed between the extraction and sensing steps, (c) a selective electrochemical detection process which is performed during the sensing step, (d) a purge step which is performed after the sensing step, (e) a charge segregation step, and (f) any combination thereof.
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Abstract
Methods and devices are provided for measuring the concentration of target chemical analytes present in a biological system. Device configuration and/or measurement techniques are employed in order to reduce the effect of interfering species on sensor sensitivity. One important application of the invention involves a method and device for monitoring blood glucose values.
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Citations
47 Claims
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1. A method for measuring the concentration of an analyte present in a biological system, said method comprising
a measurement cycle which comprises an extraction step in which a sample containing the analyte is transdermally extracted from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system, and a sensing step in which the extracted sample is contacted with sensor means to obtain a measurement signal that is related to analyte concentration, wherein said measurement cycle further comprises a process for selectively favoring-analyte-specific signal components over signal components due to interfering species, said process selected from the group consisting of (a) a differential signal process which subtracts non-analyte signal components from the measurement signal, (b) a delay step which is performed between the extraction and sensing steps, (c) a selective electrochemical detection process which is performed during the sensing step, (d) a purge step which is performed after the sensing step, (e) a charge segregation step, and (f) any combination thereof.
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19. A method for measuring the concentration of an analyte present in a biological system, said method comprising
a measurement cycle which comprises transdermally extracting the analyte from the biological system in an extraction step using an iontophoretic sampling system that is in operative contact with a skin or mucosal surface of said biological system, and contacting the extracted analyte with a sensor means in a sensing step to obtain a detectable signal which is specifically related to the analyte, wherein: -
(a) the sampling system comprises (i) a first collection reservoir containing an ionically conductive medium, a first iontophoretic sampling means for extracting substances including the analyte from the biological system into the first collection reservoir to obtain a concentration of the analyte, and a first sensor element, wherein said first sampling means and said first sensor element are in operative contact with the first collection reservoir; and
(ii) a second collection reservoir containing an ionically conductive medium, a second iontophoretic sampling means for extracting substances including the analyte from the biological system into the second collection reservoir, and a second sensor element, wherein said second sampling means and said second sensor element are in operative contact with the second collection reservoir; and
(b) the measurement cycle comprises (i) operating the first iontophoretic sampling means as an iontophoretic cathode during a first phase of the extraction step, (ii) detecting substances extracted into the first reservoir with the first sensor element during a first phase of the sensing step to obtain a first signal, (iii) purging residual signal from the sampling system in a purging step, (iv) operating the second iontophoretic sampling means as an iontophoretic cathode during a second phase of the extraction step, and (v) detecting substances extracted into the second reservoir with the second sensor element during a second phase of the sensing step to obtain a second signal, wherein at least one of said first and second signals comprises an analyte-specific signal component.
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34. A method for measuring the concentration of an analyte present in a biological system, said method comprising:
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(a) transdermally extracting the analyte from the biological system in an extraction step using an iontophoretic sampling system that comprises first and second collection reservoirs which are respectively in operative contact with first and second iontophoretic sampling means and a skin or mucosal surface of said biological system, wherein the first and second iontophoretic sampling means extract substances including the analyte from the biological system into the first and second collection reservoirs, and the first iontophoretic sampling means is operated as a cathode during the extraction step;
(b) passively collecting substances which diffuse from, or are secreted by the biological system into a third collection reservoir using a passive transdermal sampling system that is in operative contact with a skin or mucosal surface of the biological system;
(c) contacting the analyte extracted into the first collection reservoir with sensing means in a sensing step to obtain an active signal;
(d) contacting the substances collected into the third collection reservoir with sensing means in the sensing step to obtain a blank signal; and
(e) subtracting the blank signal from the active signal to provide an analyte-specific signal.
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35. A method for measuring the concentration of an analyte present in a biological system, said method comprising:
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(a) transdermally extracting the analyte from the biological system in an extraction step using an iontophoretic sampling system that comprises first, second, and third collection reservoirs which are respectively in operative contact with first, second, and third iontophoretic sampling means and a skin or mucosal surface of said biological system, wherein said first, second, and third iontophoretic sampling means respectively extract substances including the analyte from the biological system into the first, second, and third collection reservoirs, and the first and second iontophoretic sampling means are operated as cathodes during the extraction step;
(b) contacting the analyte extracted into the first collection reservoir with sensing means in a sensing step to obtain an active signal;
(c) contacting the substances extracted into the second collection reservoir with sensing means in the sensing step to obtain a blank signal; and
(d) subtracting the blank signal from the active signal to provide an analyte-specific signal.
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37. A method for measuring the concentration of an analyte present in a biological system, said method comprising:
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(a) transdermally extracting the analyte from the biological system in an extraction step using an iontophoretic sampling system that comprises first, second, and third collection reservoirs which are respectively in operative contact with first, second, and third iontophoretic sampling means and a skin or mucosal surface of said biological system, wherein said first, second, and third iontophoretic sampling means respectively extract substances including the analyte from the biological system into the first, second, and third collection reservoirs, and the first and second iontophoretic sampling means are operated as cathodes during the extraction step; and
(b) contacting the analyte extracted into the first and second collection reservoirs with sensing means in a sensing step to obtain multiple analyte-specific signals.
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39. A sampling system for measuring an analyte present in a biological system, said system comprising, in operative combination:
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(a) iontophoretic sampling means for transdermally extracting the analyte from the biological system 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 detectable signal from the extracted analyte and said signal is specifically related to the analyte; and
(c) microprocessor means in operative communication with the sampling means and the sensing means, wherein said microprocessor means controls said sampling and sensing means to provide a measurement cycle in which analyte-specific signal components are detected in the substantial absence of signal components due to interfering species.
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Specification