Sensors that are capable measuring the rate of flow of a fluid that passes
over the electrodes of the sensor. In these sensors, an electrode,
designated the flow rate-determining electrode, is used in conjunction
with the conventional electrodes, e.g., the working electrode, the
reference electrode, and the counter electrode, to determine the rate of
flow of the fluid. In one aspect, this invention provides a sensor for
measuring the concentration of an analyte in a sample of fluid when the
sample flows continuously over the electrodes of the sensor, especially
when the rate of flow of the sample is relatively low. In another aspect,
this invention provides a method for measuring the concentration of an
analyte in a sample of fluid, wherein the rate of flow of the sample
varies during the period of time that the sensor is in place. In a
preferred embodiment, the sensor employs four electrodes, namely, a
working electrode, a reference electrode, a counter electrode, and a flow
rate-determining electrode. Alternatively, a single electrode that
performs both the function of the reference electrode and the function of
the counter electrode can replace the reference electrode and the counter
electrode. In addition, a dummy electrode or a blank electrode can be used
to compensate for interference from electrochemically active species. The
reagent(s) specific to the analyte of interest is required to be deposited
on the working electrode.
