Asked by: Howard Hughes, Mitchellore-by-Sea
The sharpest object ever made is a tungsten needle that tapers down to the thickness of a single atom. It was manufactured by placing a narrow tungsten wire in an atmosphere of nitrogen and exposing it to a strong electric field in a device called a field ion microscope.
The nitrogen reacted with the tungsten more rapidly in places where the curvature was higher, eventually producing a tip of atomic radius. These tips (called nanotips) are used in scanning tunnelling microscopy (STM) to reveal the surface features of materials at atomic resolution.