System and method for preparing a sequencing device

A method to load a bead support into a reaction well of a plurality of reaction wells of a substrate, each reaction well having an inlet opening at a first surface of the substrate, the method comprising:

• introducing a suspension having a plurality of bead complexes onto the substrate, a bead complex of the plurality of bead complexes including a magnetic bead coupled to the bead support, the bead support attached to a polynucleotide, wherein the magnetic bead has a bead diameter larger than the inlet opening of the each reaction well and wherein the bead support has a bead diameter smaller than the opening of the plurality of reaction wells, wherein the bead support is a polymeric particle having a diameter in a range of 0.1 microns to 50 microns;
• moving a magnetic apparatus parallel to the first surface, the magnetic bead drawn to the first surface, the bead support entering into the reaction well of the plurality of reaction wells, wherein each reaction well of the plurality of reaction wells corresponds with an ion-sensitive sensor of a sensor array formed on the substrate;
• separating the magnetic bead from the bead support;
• and
• washing the magnetic bead away from the substrate.