Abstract: A device for performing agglutination immunoassay reactions and the like is disclosed. The device includes a first hydrophilic layer, a second liquid-occlusive layer parallel to and overlying the first layer, and a third layer parallel to and overlying the second layer. The third layer has a transparent opening for observing particles. The second layer is interposed between and in adherent relationship to the first and third layers. The second layer has at least one slot defining a channel for directing liquid conducted by capillary action through the chamber defined in conjunction with the first and third layers. This chamber has a proximate zone and a distal zone. The geometry of the chamber is modified to provide preferably outwardly diverging walls and provide a flowpath having different rates of flow per unit area along the paths.

Abstract: An improved device for performing agglutination reactions is disclosed. The device has at least one chamber with a proximate zone and a distal zone in which chamber agglutination reactions can be performed. The improvement comprises utilization in the device of a layer of liquid absorbent material for controlling overall rate of liquid flow through the chamber. The layer of liquid absorbent material is selectively impregnated with a substance to form an impregnated region and a non-impregnated region wherein the non-impregnated region is liquid absorbent and the impregnated region is liquid-occlusive. A portion of the non-impregnated region is positioned within the distal zone of the chamber so that the non-impregnated region is in liquid communication with that zone.