Despite significant progresses, cell-based assays still have major limitations due in part to their plate format. Here we present a wall-less plate technology based on unique liquid dynamics named DropArray that takes advantage of hydrophobic and hydrophilic surface properties. Liquid velocities within the DropArray plate were quantified through fluid dynamics simulation and complete retention of suspension cells experimentally demonstrated within the range of simulated shear stresses. Subsequently, we compared the DropArray technology to conventional microtiter plates in a cell-based protein-binding assay. Although the wall-less plate produced similar results with adherent cells, the advantage of the DropArray technology was absolutely clear when semi-adherent or suspension cells were used in this multi-step experimental procedure. The technology was also evaluated for cell viability assay and generated similar results to conventional plate format while enabling significant reduction in toxic reagent use. Finally, we developed a DropArray cell based-assay to evaluate a bispecific antibody designed to engage cytotoxic T cells and trigger tumor cell killing. This assay enables for the first time the visualization and quantification of the specific killing events and represents a very powerful tool to further investigate functional aspects of the cancer immunotherapy.