Abstract: Provided are multiplex devices for nucleic acid detection and methods for nucleic acid detection. The device includes at least two parallel buffer units comprised of buffer wells arranged in a row. The buffer units are connected to form a multiplex device. A mixing unit is slides along a bottom of each buffer unit to align with each buffer well in turn. When the mixing unit is aligned with a buffer well, a ball valve releases buffer from the buffer well into the mixing well. The device includes a detection unit removably coupled to the bottom of each mixing unit to receive fluids from the mixing well.