The invention provides a method, apparatus and system for detecting electrochemical oxidoreduction activity mediated by a redox enzyme at a site remote from the enzyme. In one embodiment, the method comprises immobilizing the redox enzyme on a first region of a conductive surface and contacting a substrate capable of producing a detectable signal upon oxidation or reduction with a second region of the conductive surface. The second region is electrically coupled with the first region and the redox enzyme is not present in the second region. The method further comprises exposing the immobilized redox enzyme to conditions that effect oxidation or reduction of the enzyme, and detecting oxidation or reduction of the substrate at the second region. The invention can be adapted for detecting a plurality of analytes.