Magnetic beads (or particles) having a size between 1 and 5 µm are largely used in many biochemical assays devoted to both purification and quantification of cells, nucleic acids, or proteins. Unfortunately, the use of these beads within microfluidic devices suffers from natural precipitation because of their size and density. The strategies applied thus far to cells or polymeric particles cannot be extended to magnetic beads, mainly due to their magnetization and their higher densities. We report an effective shaking device capable of preventing the sedimentation of beads that are stored in a custom PCR tube. After the characterization of the operating principle, the device is validated for magnetic beads in droplets, leading to an equal distribution between the droplets, barely affecting their generation.
Keywords: droplet microfluidics; magnetic beads; mechanical shaking; microfluidics; purification assays; sedimentation.