oss-sectional view of the assay plate shown in FIGS. 1A and 1B containing a sample volume between sharp edge boundaries; [0046]FIG. 3 is a partial cross-sectional view of a small liquid drop on a sample receiving surface away from any sharp edge boundaries; [0047]FIG. 4A is a top view of an assay plate, according to yet another embodiment of the invention; [0048]FIG. 4B is a side view of the assay