The DNA molecule of interest must be incorporated into a hairpin, and attached to a magnetic bead on one end and to an immobile glass surface on the other end.  The hairpin is attached to the glass surface via a digoxigenin-antidigoxigenin bond.  The magnetic bead is attached to the opposite end via biotin-streptavidin interaction.  Such DNA hairpin setup can be made in two ways:
:1) In the case of double-stranded DNA molecules (for whole genome sequencing, or targeted sequencing), the DNA fragment is ligated to a DNA loop at one end and a DNA fork structure, labeled with biotin and digoxigenin at the two ends.
:2) For RNA-seq, the mRNA can be trapped on a poly-T-coated bead, where reverse transcription reaction is performed on the bead to generate a cDNA hairpin.