Description:

By using a scanning probe tip, researchers can chemically modify the surface of a silicon substrate in a very well-defined way.  This allows them to "draw" nanoscale features with whatever pattern they like.  This chemical modification will then attract gold nanoparticles which will self-assemble on the surface, but only where the tip of the probe touched. 

Above is an example of a complex metal-organic nanoarchitecture.  Created by Picasso in 1962, the poster entitled “World Without Weapons” (upper-left) was translated into an input signal to the conducting SFM tip that inscribes (contact mode, line width 30 nm) a corresponding pattern of -COOH groups on the top surface of an OTS/Si monolayer specimen - the Friction (monolayer) image. Topography (bilayer): semicontact mode image of the bilayer pattern resulting from the self-assembly of an NTS overlayer on the patterned monolayer. Topography (colloidal gold pattern): semicontact mode images of the final metal-organic composite nanostructure resulting from the self-assembly of 2-6 nm [Au- citrate] particles on the amino-terminated bilayer template (lower left sketch). Individual gold particles  specifically deposited on the dove wing and tail are clearly seen in the lower-right image, showing a detailed scan of the marked square area in the full-size image (middle). The pattern inscription and imaging were carried out, with 800 x 800 raster-scanned points (3.3 ms/point), at a tip-surface bias of 8.5 V.