Disclosed is a fluidic assay device for assaying at least one property of a liquid sample comprising: a liquid sample application region; at least one test flow path in liquid flow communication with the sample application region; a reference flow path in liquid flow communication with the sample application region; and a junction region, at which the test flow path and the reference flow path contact one another, the junction region typically comprising an outlet, conduit, chamber or other portion which permits the onward flow of liquid; wherein a liquid flowing along the reference flow path, upon reaching the junction region, has the effect of preventing the flow of liquid along the test flow path. The invention relates to a fluidic device for the passage of a liquid and an assay device suitable for measurement of the amount and/or presence of an analyte in, or property of, a fluid sample.