Atomic Pen writes on individual atoms

It’d be pretty cool to have an atomic pen; think of all the secret notes you could leave for people with electron microscopes. But I’d probably keep losing the pen … and the notes too.
‘Atomic pen’ writes with individual atoms ::: Pink Tentacle

An Osaka University research team has demonstrated an â..atomic penâ. that can inscribe nano-sized text on metal by manipulating individual atoms on the surface.
According to the researchers, whose results appear in the October 17 edition of Science magazine, the atomic pen is built on a previous discovery that silicon atoms at the tip of an atomic force microscope probe will interchange with the tin atoms in the surface of a semiconductor sample when in close proximity. Using this atom-interchange phenomenon, the researchers were able to arrange individual silicon atoms one by one on a semiconductor surface to spell out the letters â..Si.â. The writing process, which took about an hour and a half to complete, was conducted at room temperature.