Liquid transfer assay devices

The present invention relates to a device for performing biochemical diagnostic assays. The device, which is preferably provided in a self-contained disposable form for use in extra-laboratory conditions, comprises two liquid flow channels of porous material which transfer liquid by capillary flow to a common site in sequentially timed manner following simultaneous application of the liquid to the ends of the channels. The channels interconnect at a certain point and then both continue in an arrangement analogous to an electrical bridge circuit. By selecting the hydraulic resistances of the arms of this circuit the flow can be controlled across the bridge. Balancing the circuit will produce null flow across the bridge and prevent the flow from one channel from dominating that from the other when the channels are saturated. Alternatively the arrangement can be such as to produce oscillating flow across the interconnection.