Device for monitoring of physiological analytes
First Claim
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1. A device for measuring the concentration of an analyte present in a biological system, said device comprisingone or more microprocessors programmed to control:
- (i) a device for extracting a sample from the biological system, said sample comprising the analyte;
(ii) a device for sensing an extracted analyte to obtain a measurement signal that is related to analyte amount or concentration in the biological system, said device comprising a sensor; and
(iii) 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 that subtracts non-analyte signal components from a measurement signal, (b) a delay that is performed between extracting the sample and sensing extracted analyte, (c) a selective electrochemical detection process that is performed during sensing, (d) a purge that is performed after sensing, (e) a charge segregation, and (f) any combination of (a) through (e).
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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
51 Claims
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1. A device for measuring the concentration of an analyte present in a biological system, said device comprising
one or more microprocessors programmed to control: -
(i) a device for extracting a sample from the biological system, said sample comprising the analyte;
(ii) a device for sensing an extracted analyte to obtain a measurement signal that is related to analyte amount or concentration in the biological system, said device comprising a sensor; and
(iii) 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 that subtracts non-analyte signal components from a measurement signal, (b) a delay that is performed between extracting the sample and sensing extracted analyte, (c) a selective electrochemical detection process that is performed during sensing, (d) a purge that is performed after sensing, (e) a charge segregation, and (f) any combination of (a) through (e). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
(a′
) dividing an extracted sample comprising the analyte into a first sample portion and a second sample portion;
(b′
) contacting the first sample portion with the sensor to obtain a first signal that predominantly comprises signal components due to interfering species and background variations;
(c′
) contacting the second sample portion with the sensor to obtain a measurement signal that comprises analyte-specific signal components; and
(d′
) subtracting the first signal from the measurement signal to obtain a signal that is specifically related to the analyte.
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3. The device of claim 2, wherein step (c′
- ) comprises contacting the second sample portion with an enzyme that reacts with the analyte to provide an analyte-specific signal.
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4. The device of claim 3, wherein the enzyme comprises glucose oxidase and the analyte is blood glucose.
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5. The device of claim 1, wherein said process (iii) comprises the differential signal process, and the differential signal process comprises:
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(a′
) extracting first and second samples, wherein at least the second sample contains extracted analyte;
(b′
) contacting the first sample with the sensor to obtain a first signal that predominantly comprises signal components due to interfering species and background variations;
(c′
) contacting the second sample with the sensor to obtain a measurement signal that comprises analyte-specific signal components; and
(d′
) subtracting the first signal from the measurement signal to obtain a signal that is specifically related to the analyte.
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6. The device of claim 5, wherein step (c′
- ) comprises contacting the second sample with an enzyme that reacts with the extracted analyte to provide an analyte-specific signal.
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7. The device of claim 6, wherein the enzyme comprises glucose oxidase and the analyte is blood glucose.
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8. The device of claim 1, wherein said process (iii) comprises the selective electrochemical detection process, said selective electrochemical detection process comprising
contacting the extracted sample with an electrochemical biosensor electrode that is maintained at a lowered potential in order to selectively detect analyte-specific signal components over signal components due to interfering species. -
9. The device of claim 8, wherein the selective electrochemical detection process comprises maintaining the biosensor electrode at a potential of about 0.5V or less.
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10. The device of claim 1, wherein said process (iii) comprises the purge, wherein said purge comprises operating the sensor for a sufficient period of time to substantially remove residual signal components from the sensor after the sensing has been carried out.
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11. The device of claim 10, wherein said sensor comprises a biosensor electrode and said biosensor electrode is operated at a potential of about 0.6V or greater during the purge.
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12. The device of claim 1, wherein the analyte is blood glucose.
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13. The device of claim 1, wherein said process (iii) comprises the charge segregation, said charge segregation comprising collecting certain interfering species preferentially at the anode.
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14. A device for measuring the concentration of an analyte present in a biological system, said device comprising
one or more microprocessors programmed to control a measurement cycle comprising (i) operating a first iontophoretic electrode as an iontophoretic cathode and a second iontophoretic electrode as an iontophoretic anode during a first phase of an extraction, wherein said first iontophoretic electrode is in contact with a first reservoir and said second iontophoretic electrode is in contact with a second reservoir, (ii) operating a first sensor element that is in contact with the first reservoir during a first phase of a sensing to obtain a first signal, (iii) purging residual signal from said first and second reservoirs in a purge, (iv) operating the second iontophoretic electrode as an iontophoretic cathode and said first iontophoretic electrode as an iontophoretic anode during a second phase of the extraction, and (v) operating a second sensor element that is in contact with the second reservoir during a second phase of the sensing 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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29. A device for measuring the concentration of an analyte present in a biological system, said device comprising:
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one or more microprocessors programmed to control a measurement cycle comprising (i) operating a first iontophoretic electrode as an iontophoretic cathode during a first phase of an extraction, (ii) operating a first sensor element that is in contact with a first reservoir during a first phase of a sensing to obtain a first signal, (iii) operating a second iontophoretic electrode as an iontophoretic cathode during a second phase of the extraction, (iv) operating a second sensor element that is in contact with a second reservoir during a second phase of the sensing to obtain a second signal, wherein at least one of said first and second signals comprises an analyte-specific signal component, (v) operating a third sensor element that is in contact with a third collection reservoir to obtain a blank signal, wherein said third collection reservoir uses a passive transdermal sampling system to collect substances that diffuse from or are secreted by the biological system, and (vi) subtracting said blank signal from said first signal to provide an analyte-specific signal. - View Dependent Claims (30, 31)
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32. A device for measuring the concentration of an analyte present in a biological system, said device comprising:
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one or more microprocessors programmed to control a measurement cycle comprising (i) operating a first iontophoretic electrode as an iontophoretic cathode during an extraction wherein said first iontophoretic electrode is in contact with a first reservoir, (ii) operating a first sensor element that is in contact with the first reservoir during a sensing to obtain an active signal, (iii) operating a second iontophoretic electrode as an iontophoretic cathode during the extraction wherein said second iontophoretic electrode is in contact with a second reservoir, (iv) operating a second sensor element that is in contact with the second reservoir during the sensing to obtain a blank signal, (v) operating a third iontophoretic electrode as an iontophoretic anode during the extraction, and (vi) subtracting said blank signal from said active signal to provide an analyte-specific signal. - View Dependent Claims (33, 34)
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35. A device for measuring the concentration of an analyte present in a biological system, said device comprising:
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one or more microprocessors programmed to control a measurement cycle comprising (i) operating a first iontophoretic electrode as an iontophoretic cathode during an extraction wherein said first iontophoretic electrode is in contact with a first reservoir, (ii) operating a first sensor element that is in contact with the first reservoir during a sensing to obtain a first analyte-specific signal, (iii) operating a second iontophoretic electrode as an iontophoretic cathode during the extraction wherein said second iontophoretic electrode is in contact with a second reservoir, (iv) operating a second sensor element that is in contact with the second reservoir during the sensing to obtain a second analyte-specific signal, and (v) operating a third iontophoretic electrode as an iontophoretic anode during the extraction. - View Dependent Claims (36, 37)
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38. A device for measuring the concentration of an analyte present in a biological system, said device comprising
one or more microprocessors programmed to control a measurement cycle comprising (i) operating an iontophoretic device for extracting a sample from the biological system, said sample comprising the analyte, (ii) operating a device for sensing the analyte in the extracted sample to obtain a measurement signal that is related to the analyte amount or concentration in the biological system, said device comprising a sensor, and (iii) 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 that subtracts non-analyte signal components from a measurement signal, (b) a delay that is performed between extracting the sample and sensing extracted analyte, (c) a selective electrochemical detection process that is performed during sensing, (d) a purge that is performed after sensing, (e) a charge segregation, and (f) any combination of (a) through (e).
Specification