Cui Yang, Pan Deng, Lianming Tong and Hongxing Xu
Here we report the optical trapping and directional transport of nanoparticles in aqueous by plasmonic nanowires. The laser illuminated on one-end of a silver nanowire and excited the localized and propagating surface plasmons. Optical forces were induced by the surface plasmons and can trap nanoparticles in aqueous. Interestingly, the trapped nanoparticles moved along the silver nanowires from the trapping site to the excitation spot of the laser. Such movements of nanoparticles were also observed on curved nanowires, on which the trajectories of particles were explicitly determined by the shape of nanowires. More importantly, for a V-shaped silver nanowire, the direction of the movement can be modulated by the polarization of the incident laser. The direction of the movement was opposite to the prediction by the scattering force due to the propagation of surface plasmons, and the driving force could involve the thermal convection of local fluid due to the heating effect. Our findings indicate a novel approach to transporting nanoparticles by plasmomic waveguides in aqueous.