Separation of colloidal nanoparticles using capillary immersion forces

Abstract

Capillary force assembly (CFA) of colloidal particles usually results in closed-packed films or particle aggregation within topographic features. In this work, it is shown that CFA can also be exploited to both localize and separate nanoparticles (d=50-200 nm) when template shape and wettability are controlled. Well-defined geometric arrangements of one to four closely spaced particles (30-50 nm separation) were realized in large arrays using this technique to demonstrate that particle aggregation during dewetting can be eliminated. Ordered SiO2 nanopillars in tight groupings were obtained by combining low-resolution e-beam lithography (>100 nm) with CFA and etching. This approach provides a simple route to fast and precise placement of nanostructures using relatively low-resolution pattern making techniques. © 2006 American Institute of Physics.