The present disclosure relates to devices and methods for detecting the presence of a target analyte in a fluid sample using an assay. A fluidic device for flow control in an assay is disclosed comprising a water impermeable substrate (300) with a flow channel (301 ) located on its upper surface; a porous reagent pad (305) located within the flow channel, where the reagent pad includes a release zone that comprises a mobilizable reagent component of an assay; a porous sensor membrane (306) located within the flow channel downstream from the reagent pad, where the sensor membrane is separated from the reagent pad by a free space diffusion zone and where the sensor membrane includes a capture zone that comprises an immobilized capture component of the assay; a water impermeable top support located within the flow channel and disposed over at least a portion of the sensor membrane; and a flow control medium that forms a water impermeable seal around a portion of the top support and sensor membrane, where the seal is configure to direct flow of fluid into the sealed portion of the sensor membrane.