The Nunc™ Edge plate has a unique design that minimizes plate evaporation. A moat designed into the perimeter of the plate can be filled with 1.7 ml sterile H20 or media. Differential evaporation rates from the inside to the outside wells in each plate are known to generate variability in both biochemical and cell based assays. A volume loss as small as 10% concentrates media components and metabolites enough to alter cell physiology, in some cases, severely. The Edge plate design incorporates large evaporative buffer zones that eliminate well-to-well variability while dramatically reducing the overall plate evaporation rate to <2% after 7 days of incubation. As water evaporates, concentrations of substances in the medium increase. Cell growth and performance can be affected and heterogeneous or biased results can occur. The outer 36 wells and corner wells are most affected by this “edge effect”. Because the Edge Plate minimizes evaporation, all samples per plate can be analyzed, increasing efficiency and reducing costs. Another source of edge effects comes from differential reagent concentrations resulting from assay washing / aspiration steps. Washing “bowed” plates with a flat plate washer manifold in ELISA and Immunocytochemistry assay formats are especially susceptible. The Edge plate is extremely flat compared to standard microplates and dramatically reduces concentration variability. Additionally, the combination of low evaporation, low background fluorescence, and extreme well flatness makes the Edge plate ideal for image based high content applications like measuring primary neuron cultures. In assays where multiple cellular targets are imaged simultaneously, all the fluorescence colors from a single location need to be focused at the same position in the imaging system. Chromatic aberration in plate bottoms make this difficult – the plate cannot be used efficiently. The Edge plate is engineered for optical superiority. Automated imaging systems (HCS) can now operate efficiently.