Controlled direct patterning of V205 nanowires onto SiO2 substrates by a microcontact printing technique

Vanadium pentoxide (V205) nanowires were directly transferred to desired patterns on SiO2 substrates using the microcontact printing (MCP) technique. The hydrophilicity of the poly(dimethylsiloxane) (PDMS) stamp exerted a strong influence on the mechanism of transfer of polar V205 nanowires onto the substrate. The V205 nanowires were transferred from the relief side of the hydrophilic stamp, whereas they were transferred from the recess edges of the hydrophobic one forming agglomerated nanowire patterns on the substrate. When the hydrophobic stamp was used, the width of the agglomerated nanowire patterns could be controlled by the concentration of the nanowire solution as well as by the width of the recess area of the PDMS stamp. This method allows us to generate nanowire patterns with a submicrometre line width, which is much smaller than a the few-micrometre sizes of PDMS stamp patterns. When the hydrophilic stamp with a small-sized ( < the average length of V205 nanowires) pattern was used, alignment of individual nanowires in the direction of the boundary of the line pattern was obtained. These results suggest that the transfer mechanism in the MCP process strongly depends on the wetting interaction between the stamp and the nanowire ink.