Sample detection to initiate timing of an electrochemical assay
First Claim
1. A method for measuring an analyte concentration in a sample of a biological fluid that is applied to an electrochemical diagnostic strip of the type that includes juxtaposed working and reference electrodes comprising(a) applying a predetermined, constant current source between the working and reference electrodes, (b) monitoring a potential difference across the electrodes, (c) applying the sample to the strip, (d) determining a sample detection time by noting when the potential difference falls below a predetermined threshold voltage, (e) applying a predetermined constant voltage to the sample, (f) measuring an electrical response at a predetermined time after applying the constant voltage, and (g) calculating the analyte concentration using the measured electrical response.
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Abstract
An electrochemical assay includes a method for determining with great accuracy the time at which an applied sample bridges a gap between the electrodes of an electrochemical cell. The method involves applying a constant small current across the gap, while monitoring the potential difference between the electrodes. The time at which the sample bridges the gap is marked by a sharp drop in the potential. A constant voltage is applied after the sample is detected, and the current and/or charge through the sample is monitored over a period of time. From the measured current or charge, the analyte concentration of interest can be calculated.
573 Citations
15 Claims
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1. A method for measuring an analyte concentration in a sample of a biological fluid that is applied to an electrochemical diagnostic strip of the type that includes juxtaposed working and reference electrodes comprising
(a) applying a predetermined, constant current source between the working and reference electrodes, (b) monitoring a potential difference across the electrodes, (c) applying the sample to the strip, (d) determining a sample detection time by noting when the potential difference falls below a predetermined threshold voltage, (e) applying a predetermined constant voltage to the sample, (f) measuring an electrical response at a predetermined time after applying the constant voltage, and (g) calculating the analyte concentration using the measured electrical response.
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7. A meter for measuring an analyte concentration in a sample of a biological fluid that has been applied between a working and reference electrode of a diagnostic strip comprising, in electrical communication,
(a) means for applying a predetermined current between the working and reference electrodes, (b) means for monitoring a potential difference across the electrodes, (c) means for determining when the potential difference falls below a predetermined threshold voltage to indicate sample detection, (d) means responsive to sample detection for applying a predetermined constant voltage to the sample, (e) means for measuring a resulting electrical response, and (f) means for calculating the analyte concentration by using the measured electrical response.
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13. A method for measuring an analyte concentration in a sample of a biological fluid that is applied to an electrochemical diagnostic strip of the type that includes juxtaposed working and reference electrodes comprising
(a) applying a predetermined, constant current source between the working and reference electrodes, (b) monitoring a potential difference across the electrodes, (c) applying the sample to the strip, (d) determining a sample detection time by noting when the potential difference falls below a predetermined threshold voltage, (e) applying a predetermined constant voltage to the sample, (f) applying a second predetermined voltage to the sample after a first predetermined time, (g) measuring an electrical response at a predetermined time after the first predetermined time, and (h) calculating the analyte concentration using the measured electrical response.
Specification