Electrochemical test strip for reducing the effect of direct interference current

Abstract

This invention describes an electrochemical sensor which is adapted to reduce the effects of interfering compounds in bodily fluids when measuring an analyte in such fluids using an electrochemical strip. The sensor includes a substrate, a first and second working electrodes, and a reference electrode. A reagent layer is disposed on the electrodes such that, in one embodiment it completely covers all of the first working electrode, but only partially covers the second working electrode and, in a second embodiment, it only covers a portion of the first and the second working electrode. The portion of the working electrodes not covered by the reagent layer and is used to correct for the interference effect on the analyte measurement.

Description

PRIORITY [0001] The present invention claims priority to the following U.S. Provisional Applications: U.S. Provisional Application Ser. No. 60 / 516,252 filed on Oct. 31, 2003; U.S. Provisional Application Ser. No. 60 / 558,424 filed on Mar. 31, 2004; and U.S. Provisional Application Ser. No. 60 / 558,728 filed on Mar. 31, 2004. Which applications are hereby incorporated herein by reference. RELATED APPLICATIONS [0002] The present invention is related to the following co-pending U.S. applications: U.S. patent application Ser. No. ______ [Attorney Docket Number DDI-5027 USNP], filed on Oct. 29, 2004; U.S. patent application Ser. No. ______ [Attorney Docket Number DDI-5042 USNP], filed on Oct. 29, 2004; U.S. patent application Ser. No. ______ [Attorney Docket Number DDI-5065], filed on Oct. 29, 2004; U.S. patent application Ser. No. ______ [Attorney Docket Number DDI-5066], filed on Oct. 29, 2004; and U.S. patent application Ser. No. ______ [Attorney Docket Number DDI-5067], filed on Oct. 2...

AI Technical Summary

Benefits of technology

"The invention is about an electrochemical sensor that reduces interference. The sensor has a substrate with two working electrodes and a reference electrode. In one embodiment, a reagent layer covers only one of the working electrodes, and the other electrode has both covered and uncovered areas. The uncovered area can measure interfering substances, and the data from it is used to correct for the effects of interference on the glucose measurement. In another embodiment, both working electrodes are only partially covered with the reagent layer, and the data from the uncovered areas is used to estimate the interferent oxidation current and calculate a corrected glucose current. Overall, this invention improves the accuracy of electrochemical glucose sensors by reducing interference."

Problems solved by technology

In particular, desirable oxidation current results from the interaction of the mediator with the analyte of interest (e.g., glucose) while undesirable oxidation current is generally comprised of interfering compounds being oxidized at the electrode surface and by interaction with the mediator.

However, this technique is not always successful since some interfering compounds such as acetaminophen do not have a net negative charge, and thus, can pass through a negatively charged membrane.

Nor would this technique reduce the oxidation current resulting from the interaction of interfering compounds with some mediators.

However, such selective membranes typically make the test strip more complicated to manufacture and increase the test time because the oxidized glucose must diffuse through the selective membrane to get to the electrode.

A disadvantage of this strategy is that mediators having a relatively low potential are often difficult to synthesize, unstable and have a low water solubility.

A disadvantage of this strategy is that it requires that the test strip include an additional electrode and electrical connection (i.e., the dummy electrode) which cannot be used to measure glucose.

The inclusion of dummy electrode is an inefficient use of an electrode in a glucose measuring system.

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