A device for the detection of a target analyte in solution is provided. The device comprises a gate-keeper membrane made of a substrate having a first receptor surface for exposure to the target analyte and a second opposing surface exposed to a detector, wherein the substrate is adapted to incorporate pores sufficient to permit passage of a reporter through the membrane from exposure to the first receptor surface to the second opposing surface; one or more receptors anchored on the first surface of the substrate which bind with the target analyte, wherein binding of the receptor with the target analyte alters the passage of the reporter through the pores of the membrane; and one or more detectors which interact with reporter that passes through the membrane and emits a detectable signal that permits quantification of reporter in the detection reservoir.