High density self-contained biological analysis

A container for performing a plurality of reactions on a fluid sample in a closed system comprising

• a high density reaction zone provided in the closed system comprising
• a channel for receiving the sample into the high density reaction zone,
• a plurality of high density reaction wells fluidly connected to the channel, each high density reaction well comprising one or more reagents, and
• a barrier layer disposed between the channel nd the high density reaction wells that minimizes cross-contamination between high density reaction wells upon introduction of the sample to the high density reaction zone, wherein the barrier layer is a pierced layer having one or more piercings per reaction well, and wherein the piercings extend through the pierced layer and are large enough to allow the fluid sample to pass in the presence of a force, but small enough to substantially prevent the fluid sample from passing absent the force,
• wherein the high density reaction zone is configured such that the sample received through the channel flows across the pierced layer, over all of the piercings, and through the piercings into the high density reaction wells.