In this paper

we present a coating AFM tip method to facilitate the dip-pen nanolithography (DPN) processes. The small amount of ink can be limited to the apex of atomic force microscope (AFM) tip by adjusting AFM operation parameters. With this automatic AFM-engage system overloading ink

usually disturbing imaging and manipulating

can be avoided. Thereby

a uniform nanoarray of CuCl2 is constructed on a DNA molecule. The unique technique may provide a novel approach to precisely modify biological molecule at the nano-meter scale.