Influence of probe density on the hybridization efficiency of 15mer targets. (A) Control of probe coverage by a sequential loading strategy at low probe concentration. Three steps were applied, with injections of a 10 nM (curve 1), a 10 nM (curve 2) and a 1 µM (curve 3) probe solution followed by a buffer rinse, respectively. The corresponding probe coverages were calculated on the right axis, assuming the 1 µM probe solution rendered 100% probe coverage. (B) Hybridization efficiency as a function of probe coverage for the T15-0 and T15-1 targets (in 2 µM solutions), respectively.