This invention relates generally to the field of nucleic acid detection. In particular, the invention provides a lab-on-chip system for analyzing a nucleic acid, which system comprises, inter alia, controllably closed space, and a target nucleic acid can be prepared and/or amplified, and hybridized to a nucleic acid probe, and the hybridization signal can be acquired if desirable, in the controllably closed space without any material exchange between the controllably closed space and the outside environment. Methods for analyzing a nucleic acid using the lab-on-chip system is also provided.