A filling apparatus for filling a microplate. The microplate having a plurality of wells each sized to receive an assay. The filling apparatus can comprise an assay input layer having a first surface and an opposing second surface. The assay input layer can comprise an assay input port extending from the first surface to the second surface and at least one pressure nodule extending from the second surface. An output layer can comprise a plurality of staging capillaries each having an inlet and an outlet. A intermediate layer can be disposed between the assay input layer and the output layer. The intermediate layer can be flexible and comprise a plurality of microfluidic channels and a flow aperture being in fluid communication with the assay input port and the plurality of microfluidic channels. The assay input layer can be moveable relative to the intermediate layer such that the at least one pressure nodule engages the intermediate layer to apply a clamping force on at least a portion of one of the plurality of microfluidic channels to reduce flow of the assay therethrough.