Self-assembly of particle clusters enabled by on-chip plasmonic nanotweezers

Integration of plasmonic nanotweezers on silicon chips holds promise for many lab-on-a-chip applications. In this work, optical trapping of single beads and self-assembled clusters composed of up to nine beads is achieved using plasmonic nanotweezers fabricated on a silicon nanophotonic waveguide. We statistically analyze the preferred orientations, the probability of occurrence and the stability of the different cluster configurations. We evidence that the presence of two potential barriers along the waveguide edges results in the enhanced stability of some specific cluster configurations. Our results pave the way for further development of hybrid plasmonic-photonic nanotweezers and lab-on-chips.