Microprocessors, devices and methods for use in analyte monitoring systems

• US 7,519,478 B2
• Filed: 11/09/2005
• Issued: 04/14/2009
• Est. Priority Date: 03/22/2002
• Status: Expired due to Term

• Current Assignee: LifeScan IP Holdings, LLC
• Original Assignee: Animas Technologies LLC (Johnson & Johnson)
• Inventors: Tamada, Janet A., Bartkowiak, Miroslaw, Kulcu, Eray, Harper, Wesley S., Lesho, Matthew J.
• Primary Examiner(s): Brusca; John S
• Application Number:
  US11/270,063
• Publication Number:
  US 20060063218A1
• Time in Patent Office: 1,252 Days
• Field of Search: None
• US Class Current: 702/19
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: Y10T 436/144444 Glucose

Abstract

The present invention comprises one or more microprocessors programmed to execute methods for improving the performance of an analyte monitoring device including prediction of glucose levels in a subject by utilizing a predicted slower-time constant (1/k₂). In another aspect of the invention, pre-exponential terms (1/c₂) can be used to provide a correction for signal decay (e.g., a Gain Factor). In other aspects, the present invention relates to one or more microprocessors comprising programming to control execution of (i) methods for conditional screening of data points to reduce skipped measurements, (ii) methods for qualifying interpolated/extrapolated analyte measurement values, (iii) various integration methods to obtain maximum integrals of analyte-related signals, as well as analyte monitoring devices comprising such microprocessors. Further, the present invention relates to algorithms for improved optimization of parameters for use in prediction models that require optimization of adjustable parameters.

Claims

1. A method of obtaining an analyte value in biological fluid of a user with an analyte sensor having two electrode sets coupled to a microprocessor, the method comprising:

contacting the two electrode sets with biological fluid of a user, in which each electrode set includes an iontophoretic electrode and an electrochemical sensor element in contact with the biological fluid and each of the two iontophoretic electrodes function as either a cathode or anode while in contact with the fluid;

measuring a current signal at each of the anode and cathode;

measuring a current signal related to the analyte from the sensor element associated with a cathode at each half-measurement cycle;

determining, via the microprocessor a baseline current signal for a given sensor in which the iontophoretic electrode functions as a cathode based on the last two data points of the current signals from the given sensor in a previous half-cycle in which the given sensor is associated with an anode;

subtracting, via the microprocessor, the background baseline current from the current signal related to the analyte;

integrating, via the microprocessor, the current signal related to the analyte over time;

upon over subtraction of the current signal related to the analyte, stopping, via the microprocessor, the integrating of the current signal related to the analyte when the maximum integral is reached;

correlating the maximum integral of the current signal related to the analyte as being proportional to the analyte value; and

displaying, via the microprocessor, the analyte value of the biological fluid of the user for diagnostic purposes.

3. The method of claim 1, in which the analyte-related signal is related to an amount or concentration of glucose.

2. A method of obtaining an analyte value in biological fluid of a user with an analyte sensor having two electrode sets, the method comprising:

contacting the two electrode sets with biological fluid of a user, in which each electrode set includes an iontophoretic electrode and an electrochemical sensor element in contact with the biological fluid and each of the two iontophoretic electrodes function as either a cathode or anode while in contact with the fluid;

measuring a current signal at each of the anode and cathode;

measuring a current signal related to the analyte from the sensor element associated with a cathode at each half-measurement cycle;

determining, via the microprocessor, baseline current signal for a given sensor in which the iontophoretic electrode functions as a cathode based on the last two data points of the current signals from the given sensor in a previous half-cycle in which the given sensor is associated with an anode;

subtracting, via the microprocessor, the background baseline current from the current signal related to the analyte;

integrating, via the microprocessor, the current signal related to the analyte over time;

upon over subtraction of the current signal related to the analyte, recalculating a background baseline current based on the last two data points from the current related to the analyte at the cathode;

subtracting, via the microprocessor, the recalculated background baseline current from the current related to the analyte;

integrating, via the microprocessor, the background subtracted current signal over time to obtain the charge signal as being proportional to a value of the analyte; and

displaying, via the microprocessor, the analyte value of the biological fluid of the user for diagnostic purposes.

4. The method of claim 2, in which the analyte-related signal is related to an amount or concentration of glucose.