An apparatus for determining an analyte in a sample comprising (a) a test strip comprising (i) first and second electrodes disposed to contact a test cell for receiving sample, wherein an immobilizable test reagent comprising an analyte binding portion is disposed in the test cell, said immobilizable test reagent being immobilizable on the first electrode via a non-analyte specific linking agent, wherein said immobilizable test reagent is immobilized before or after addition of sample to the test strip; and (ii) a mobile test reagent comprising a redox enzyme portion and an analyte binding portion, such that the mobile test reagent has a first distribution relative to the electrodes when analyte is present in the sample and a second distribution relative to the electrodes when analyte is not present in the sample, one of said first and second distributions being asymmetric between the electrode, and the other of the first and second distributions being symmetric or less symmetric between the electrodes; and (b) a circuit for detecting the symmetric, less asymmetric, or asymmetric distribution of the mobile test reagent in the test cell in the absence of an applied external potential or current; and (c) means for communicating the detected distribution to a user. (a) a test strip comprising (i) first and second electrodes disposed to contact a test cell for receiving sample, wherein an immobilizable test reagent comprising an analyte binding portion is disposed in the test cell, said immobilizable test reagent being immobilizable on the first electrode via a non-analyte specific linking agent, wherein said immobilizable test reagent is immobilized before or after addition of sample to the test strip; and (ii) a mobile test reagent comprising a redox enzyme portion and an analyte binding portion, such that the mobile test reagent has a first distribution relative to the electrodes when analyte is present in the sample and a second distribution relative to the electrodes when analyte is not present in the sample, one of said first and second distributions being asymmetric between the electrode, and the other of the first and second distributions being symmetric or less symmetric between the electrodes; and (i) first and second electrodes disposed to contact a test cell for receiving sample, wherein an immobilizable test reagent comprising an analyte binding portion is disposed in the test cell, said immobilizable test reagent being immobilizable on the first electrode via a non-analyte specific linking agent, wherein said immobilizable test reagent is immobilized before or after addition of sample to the test strip; and (ii) a mobile test reagent comprising a redox enzyme portion and an analyte binding portion, such that the mobile test reagent has a first distribution relative to the electrodes when analyte is present in the sample and a second distribution relative to the electrodes when analyte is not present in the sample, one of said first and second distributions being asymmetric between the electrode, and the other of the first and second distributions being symmetric or less symmetric between the electrodes; and (b) a circuit for detecting the symmetric, less asymmetric, or asymmetric distribution of the mobile test reagent in the test cell in the absence of an applied external potential or current; and (c) means for communicating the detected distribution to a user.