Patent ID: 7579184

Claim:
A conductimetric assay device for the detection of an analyte in a flowing fluid sample comprising: (a) a capture zone having a length along a direction which the fluid sample flows over a substrate and an increasing width; (b) a set of two electrodes spaced across the increasing width of the capture zone linked to a circuit such that a distance between the set of two electrodes increases along the direction of flow of the fluid sample; (c) a first capture agent capable of binding the analyte, the first capture being affixed to the substrate in the capture zone; and (d) an analyte-capture agent complex comprising (i) a second capture agent capable of binding the analyte and having a conductive moiety and (ii) analyte bound to the second capture agent, the analyte-capture agent complex being present in the fluid sample which flows over the substrate in said capture zone; wherein the first capture agent binds to the analyte in the analyte-capture agent complex, thereby holding the second capture agent with the conductive moiety between the two electrodes to complete the circuit and produce a conductive signal.