Fill sufficiency method and system
Described and illustrated herein are one exemplary method and a measurement system having a meter and a test strip. The test strip has a first working electrode, reference electrode and second working electrode. In this method, acceptable fill data from known first current and known second current are used to predict an estimated second current at proximate the second time period (for a given batch of test strips) during the test sequence. The estimated second current at proximate the second time interval is then compared with a measured actual second current at proximate the second time interval during an actual test to determine if the measured actual second current is substantially equal to or within an acceptable percent deviation from the estimated second current so as to determine sufficient volume of a physiological fluid sample in the test strip.
1. A method of determining the volume sufficiency of a fluid sample applied to a test strip electrically connected to a meter for measuring a glucose concentration, the method comprising:
providing the test strip having;
a first working electrode;
a shared reference electrode;
a second working electrode;
at least one mediator layer disposed over at least a portion of the first working electrode, at least a portion of the shared reference electrode and at least a portion of the second working electrode;
a first analyte reagent layer disposed over at least a portion of the mediator layer disposed over at least a portion of the first working electrode; and
a second analyte reagent layer disposed at least over a portion of the mediator layer disposed over at least a portion of the second working electrode and at least a portion of the shared reference electrode;
depositing a physiological sample over at least a portion of one of the first and second analyte reagent layer;
after the depositing, applying approximately a first voltage for a first time period between the first working electrode, the shared reference electrode and the second working electrode;
measuring a first current during the first time period at the first working electrode;
applying a voltage other than first voltage for a second time period after the first time period between the shared reference electrode and the second working electrode;
measuring a second current at the second working electrode and the reference electrode;
predicting an estimated second current during the second time period at the second working electrode, in which the estimated second current during the second time period is determined from the measured first current as correlated to known first current data and known second current data from sufficiently filled samples;
evaluating a difference between the measured second current and the estimated second current during the second time period; and
displaying an error condition indicating volume insufficiency if the difference between the measured second current during the second time period and the estimated second current during the second time period are greater than an acceptance limit.
2. The method of claim 1 , in which the first voltage comprises zero volts.
3. The method of claim 1 , in which the first voltage is applied between the reference electrode, the first working electrode and the second working electrode for about zero seconds to about 4 seconds.
4. The method of claim 1 , in which the voltage other than first voltage for a second time period after the first time period comprises a voltage of any value from about 200 millivolts to about 500 millivolts.
5. The method of claim 1 , in which the acceptance limit comprises from about −40% to about +40% between the measured and estimated second currents.