Microfluidic devices, solid supports for reagents and related methods

A method of conducting a reaction using the solid supports in a microfluidic device, the microfluidic device comprising:

• a substrate having a plurality of solid support containment regions that are sized and configured to capture a plurality of solid supports having a diameter d, wherein each of the solid supports has a reagent attached via a labile reagent/support bond and the reagent is configured to be cleaved from the support via a cleaving operation, and wherein the reagent comprises a DNA primer or probe for a PCR reaction, and the solid support containment regions have a cylindrical shape having a diameter of 1.05d to 1.55d and a depth of 1.2d to 1.8d, the solid supports comprising magnetic solid supports, the method comprising:
• loading the solid supports in the plurality of solid support containment regions by applying a magnet or magnetic field, wherein the magnet or magnetic field is applied to move the solid supports across the substrate and into the plurality of solid support containment regions, wherein the plurality of solid support containment regions and the plurality of solid supports are sized and configured such that a single one of the plurality of solid supports is retained in a corresponding single one of the plurality of solid support containment regions;
• and
• loading a sample and a PCR master mix in the plurality of solid support containment regions;
• and
• after applying the magnetic field to move the solid supports across the substrate and into the containment regions and loading the sample and the PCR master mix, flowing a sealing fluid comprising oil, liquid polymer, or fluorocarbon liquid over the plurality of solid support containment regions to seal the plurality of containment regions, wherein the sealing fluid isolates reagents in the plurality of solid support containment regions and fluidically isolates each of the plurality of solid support containment regions during a reaction.