Figure 4.

Schematic diagram illustrating the mechanism of motion generation caused by DNA immobilization and hybridization. Immobilization of ssDNA on the top surface bends the cantilever down. The persistence length of ssDNA is 7.5 Å, and this flexibility provides an entropic driving force for forming curved interfaces. Hybridization increases the persistence length to about 50 nm, which significantly reduces the configurational entropic driving force, thereby reducing the importance of curvature producing an upward cantilever motion.