  We discuss two aspects of the plasmofluidic assembly of plasmonic
nanostructures at the metal fluid interface. First, we experimentally show how
three and four spot evanescent wave excitation can lead to unconventional
assembly of plasmonic nanoparticles at the metal fluid interface. We observed
that the pattern of assembly was mainly governed by the plasmon interference
pattern at the metal fluid interface, and further led to interesting dynamic
effects within the assembly. The interference patterns were corroborated by 3D
finite difference time domain simulations. Secondly, we show how anisotropic
geometry, such as Ag nanowires, can be assembled and aligned in unstructured
and structured plasmofluidic fields. We found that by structuring the
metal-film, Ag nanowires can be aligned at the metal fluid interface with a
single evanescent wave excitation, thus highlighting the prospect of assembling
plasmonic circuits in a fluid. An interesting aspect of our method is that we
obtain the assembly at locations away from the excitation points, thus leading
to remote assembly of nanostructures. The results discussed herein may have
implications in realizing a platform for reconfigurable plasmonic
metamaterials, and a test-bed to understand the effect of plasmon interference
on assembly of nanostructures in fluids.
