A method and apparatus for electrochemical detection of analyte in a sample makes use of a binding interaction and relies on the discovery that asymmetric distribution of a redox enzyme between two electrodes that occurs when a redox enzyme-containing reagent is immobilized at the surface of one electrode can be detected as a chemical potential gradient arising from an asymmetry in the distribution of oxidized or reduced redox substrate. This chemical potential gradient can be detected potentiometrically by observing the potential difference between the electrodes in an open circuit, or amperometrically by observing the current flow between the electrodes when the circuit is closed. In both cases, the observation of asymmetry can be done without the application of an external potential or current to the electrodes.