Dielectric microsphere manipulation and chain assembly by counter-propagating waves in a channel waveguide

We study the formation and the propulsion properties of chains of dielectric microspheres in the evanescent field of a channel waveguide made by Cs(+) ion-exchange. Particle chains are shown to move faster than single particles. We exploit counter-propagating waves for axial positioning of single and chains of microspheres. The particles can be propelled back and forth at will, and trapped at a given point for several minutes. We demonstrate that this technique can also be used to assemble a long, one-particle wide, chain.