A fluidic device for flow control in an assay comprising: a water impermeable substrate (300, 500, 600, 800, 900, 1000) with a flow channel (301, 501, 801, 1001, 1101) located on its upper surface; a porous reagent pad (305, 405, 505) located within the flow channel (301, 501, 801, 1001, 1101), where the porous reagent pad (305, 405, 505) includes a release zone that comprises a mobilizable reagent component of an assay; a porous sensor membrane (306, 406, 506, 706, 806) located within the flow channel (301, 501, 801, 1001, 1101) downstream from the porous reagent pad (305, 405, 505), where the porous sensor membrane (306, 406, 506, 706, 806) includes a capture zone that comprises an immobilized capture component of the assay; a free space diffusion zone (309, 409, 509, 809) located within the flow channel (301, 501, 801, 1001, 1101) separating the porous reagent pad (305, 405, 505) from the porous sensor membrane (306, 406, 506, 706, 806), where the free space diffusion zone (309, 409, 509, 809) comprises a volume; a water impermeable top support (308, 408, 508) located within the flow channel (301, 501, 801, 1001, 1101) and disposed over at least a portion of the porous sensor membrane (306, 406, 506, 706, 806); a flow control medium (304, 504, 804) that extends about at least a portion of the porous sensor membrane (306, 406, 506, 706, 806) upstream from the capture zone, where the flow control medium (304, 504, 804) forms a water impermeable seal around a portion of the water impermeable top support (308, 408, 508) and the at least a portion of the porous sensor membrane (306, 406, 506, 706, 806), such that, when a fluid flow is present in the device, the water impermeable seal directs flow of incoming fluid upstream into the sealed portion of the porous sensor membrane (306, 406, 506, 706, 806); and a cover (311, 511, 811, 1011, 1111) is disposed over at least a portion of the top support (308, 408, 508); wherein the flow control medium (304, 504, 804) comprises a material that is initially dispensed in a liquid phase to the fluidic device and subsequently cured or dried to become a solid phase. a water impermeable substrate (300, 500, 600, 800, 900, 1000) with a flow channel (301, 501, 801, 1001, 1101) located on its upper surface; a porous reagent pad (305, 405, 505) located within the flow channel (301, 501, 801, 1001, 1101), where the porous reagent pad (305, 405, 505) includes a release zone that comprises a mobilizable reagent component of an assay; a porous sensor membrane (306, 406, 506, 706, 806) located within the flow channel (301, 501, 801, 1001, 1101) downstream from the porous reagent pad (305, 405, 505), where the porous sensor membrane (306, 406, 506, 706, 806) includes a capture zone that comprises an immobilized capture component of the assay; a free space diffusion zone (309, 409, 509, 809) located within the flow channel (301, 501, 801, 1001, 1101) separating the porous reagent pad (305, 405, 505) from the porous sensor membrane (306, 406, 506, 706, 806), where the free space diffusion zone (309, 409, 509, 809) comprises a volume; a water impermeable top support (308, 408, 508) located within the flow channel (301, 501, 801, 1001, 1101) and disposed over at least a portion of the porous sensor membrane (306, 406, 506, 706, 806); a flow control medium (304, 504, 804) that extends about at least a portion of the porous sensor membrane (306, 406, 506, 706, 806) upstream from the capture zone, where the flow control medium (304, 504, 804) forms a water impermeable seal around a portion of the water impermeable top support (308, 408, 508) and the at least a portion of the porous sensor membrane (306, 406, 506, 706, 806), such that, when a fluid flow is present in the device, the water impermeable seal directs flow of incoming fluid upstream into the sealed portion of the porous sensor membrane (306, 406, 506, 706, 806); and a cover (311, 511, 811, 1011, 1111) is disposed over at least a portion of the top support (308, 408, 508); wherein the flow control medium (304, 504, 804) comprises a material that is initially dispensed in a liquid phase to the fluidic device and subsequently cured or dried to become a solid phase.