Integrated sequencing apparatuses and methods of use

A nucleic acid sequencing method comprising

• (a) presenting a plurality of target nucleic acids on a detection surface;
• (b) providing a collection of reagent droplets, individual droplets in the collection comprising different sequencing reagents, the collection of droplets comprising sufficient reagents to complete a cycle of the sequencing reaction;
• (c) delivering droplets from the collection to the detection surface in a sequential order to complete the cycle of the sequencing reaction for the target nucleic acids, wherein at least a subset of individual droplets in the collection are discretely delivered to the detection surface and discretely removed from the detection surface;
• and
• (d) re-using individual droplets in the subset in a subsequent cycle of the sequencing reaction.