Disclosed are methods and systems concerning flow cells for sequencing a nucleic acid sample that may be characterized by the following components: (a) a substrate having an inner surface facing a library sequencing region, and an outer surface; (b) a plurality of a plurality of forward and reverse amplification primers immobilized over the inner surface and providing a nucleic acid library capture surface of the library sequencing region; (c) a plurality of electrodes disposed along the inner surface directly under at least some of the forward and reverse amplification primers, and configured to provide, when charged, an electric field through the library capture surface and into the library sequencing region; (d) electrical leads connected to the plurality of electrodes to permit the electrodes to be independently addressable; and (e) fluidic couplings configured to deliver a plurality of nucleic acid libraries to the flow cell during different time periods.