Speed Bump: Tip’s tricks sort DNA, write at nanoscale

Using an old tool in surprising new ways, scientists in California are making molecules race down the sloping sides of a minuscule silicon spike ordinarily reserved for poking at atoms. The novel role for the spike, which is the tip of an instrument known as an atomic-force microscope, or AFM, could lead to advances in DNA sequencing, nanofabrication of devices, and other technologies, the scientists say.