Error detection in analyte measurements based on measurement of system resistance
Inventors
Diamond, Steven • Harding, Ian • Williams, Richard
Assignees
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Publication Number
US-8192610-B2
Publication Date
2012-06-05
Expiration Date
Abstract
Measurement of the series track resistance of a working and counter electrode pair in an electrochemical test strip provide error detection for multiple variations in the quality of the test strip, as well as the operation of strip in the test meter. In particular, a single measurement of series resistance can be used to detect and generate an error message when an incorrect reading is likely to result due to (1) damaged electrode tracks, (2) fouled electrode surfaces, (3) dirty strip contacts, or (4) short circuit between the electrodes.
Core Innovation
The method determines an analyte in a sample using an electrochemical test strip with working and counter electrodes. A potential difference, Vapp, is applied to the electrodes, and a current signal is observed to provide an initial determination of analyte and to determine a plateau current, Iplateau, reflecting recycling or shuttling of mediator between the electrodes.
The applied potential is switched off at time tswitch and the magnitude, Vdrop, of a voltage drop arising from series electrode resistance, if present, is determined. The track resistance is calculated from Vdrop and the plateau current such that Rtrack equals Vdrop divided by Iplateau, and the determined magnitude of Rtrack is compared against a predetermined range.
The test is rejected if the magnitude of Rtrack falls outside the predetermined range. If the magnitude is within the predetermined range, the initial determination of analyte is corrected to compensate for track resistance, and the result is displayed or communicated.
Claims Coverage
The document contains one independent claim describing an analyte determination method with one inventive feature that combines track-resistance determination, rejection of out-of-range tests, and correction of the analyte determination when track resistance is acceptable.
Analyte determination with mediator plateau current and post-switch-off track resistance check
Applying Vapp to an electrochemical test strip having working and counter electrodes; observing a current signal sufficient to provide an initial determination of analyte and a plateau current, Iplateau; switching off the applied potential at time tswitch and determining Vdrop arising from series electrode resistance, if present; calculating track resistance Rtrack as Vdrop divided by Iplateau; comparing Rtrack against a predetermined range; rejecting the test if Rtrack falls outside the range; and, if within the predetermined range, correcting the initial determination of analyte to compensate for track resistance and displaying or communicating the corrected result.
The claim integrates analyte determination based on mediator recycling or shuttling with a post-switch-off series-electrode-resistance assessment. It uses a predetermined acceptable range of Rtrack to reject faulty tests and to correct the analyte determination when track resistance is within range.
Stated Advantages
Enables rejection of a test when series electrode track resistance indicates a magnitude of Rtrack outside a predetermined acceptable range.
Corrects an initial determination of analyte to compensate for track resistance when Rtrack is within the predetermined range.
Provides results through display or communication based on the corrected determination of analyte.
Documented Applications
Determining analyte in a sample using an electrochemical test strip, including glucose as the analyte with the sample as a blood sample [procedural detail omitted for safety].
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