Through the use of magnetic traps, constant magnetic force can be applied to millions of DNA hairpin-tethered magnetic beads in parallel.  The magnetic force can be easily adjusted by changing the distance between the trap and the magnetic beads.  The number of eads that can be simultaneously monitored, which determines the read throughput of this platform, is limited by the bead size, length of the tethered DNA hairpin, and the optical resolution limit. Currently, a density of 750 K/mm (comparable to an Illumina HiSeq 2000) can be achieved.