An apparatus and method for DNA hybridization is provided. The apparatus and method work in conjunction with a substrate comprising an upper surface having probes. The apparatus may comprise a material which abuts the substrate, with at least a portion of the material being pliable. The material and the substrate form a plurality of chambers, each chamber having a bottom including at least a portion of the upper surface, at least one sidewall, and an opening. The apparatus further comprises a mechanism for closing the openings of the chambers, thereby sealing the chambers.