Flow cells

A method, comprising:

• introducing a plurality of complexes to a flow cell including:
• a plurality of chambers;
• a plurality of depressions within each of the plurality of chambers;
• primers attached within each of the plurality of depressions;
• and
• a capture site in each of the plurality of chambers;
• wherein each of the complexes includes:
• a carrier;
• and
• sequencing-ready nucleic acid fragments attached to or contained within the carrier;
• whereby one of the complexes attaches to a respective one of the capture sites in at least some of the plurality of chambers;
• and
• causing the carrier of each complex to release the sequencing-ready nucleic acid fragments therefrom, whereby walls of the respective chambers restrict transport and seeding of the sequencing-ready nucleic acid fragments to respective depressions within each of the respective chambers.

A method, comprising:

• introducing a fluid including a plurality of complexes into a flow cell, wherein each of the plurality of complexes includes:
• a solid support;
• and
• sequencing-ready nucleic acid fragments attached to the solid support;
• whereby at least some of the plurality of complexes are immobilized by a respective capture site in the flow cell;
• and
• introducing an external immobilizing agent to the flow cell, thereby generating at least a liquid droplet around the immobilized complexes.