Optical manipulation of neutral nanoparticles suspended in a microfluidic channel

An optical method to deterministically manipulate nanosized particles in suspensions within confined microfluidic devices is introduced. We show that under appropriate conditions strong dielectrophoretic forces several orders of magnitude larger than the Brownian force can be generated using an external optical actuation. A self-consistent coupled point-dipole model that includes the redistribution of charges on the channel boundaries allows us to specify the underlying mechanisms and estimate the optical forces experienced by a nanoparticle.