Photothermal forces enhanced by nanoneedle array for nanoparticle manipulation

Abstract Plasmonic nanostructures provide strong electromagnetic fields enhancement and confinement for nanoparticle trapping. Here, we study the thermal and optical nanoparticle trapping effects using plasmonic nanoneedles array. Results show that the photo-thermal force outside the nanostructure can affect movements of nanoparticles in the far field as a result of heat transfer. The thermal force is decreased about one order of magnitude for nanoparticle at about 6 μ m away from the nanostructure where the optical force is no longer effective. Plasmonic nanoneedles with high aspect ratio provides more trapping positions in three dimensions. The thermal force together with the near field optical force make plasmonic nanoneedles array a flexible and wide working range manipulation strategy for nanoparticles.