Optofluidic transport and manipulation of plasmonic nanoparticles by thermocapillary convection

Optothermal control of fluid motion has been suggested as a powerful way of controlling nanomaterials in micro- or nanofluidic samples. Methods based on merely thermal convection, however, often rely on high temperature for achieving fluid velocities suitable for most practical uses. Here, we demonstrate an optofluidic approach based on Marangoni or thermocapillary convection to steer and manipulate nano-objects with high accuracy at an air/liquid interface. By experiments and numerical simulations, we show that the fluid velocities achieved by this approach are more than three orders of magnitude stronger compared to natural convection and that it is possible to control the transport and position of single plasmonic nanoparticles over micrometer distances with high accuracy.