Highly Flexible and Ultraprecise Manipulation of Light-Levitated Femtoliter/Picoliter Droplets.

Ultraprecise manipulation of the droplets at the microscale is a promising paradigm for broad implications in reagent transport and element analysis, but the existing strategies still suffer from cross-contamination or the miscellaneous auxiliaries. Inspired by the levitation, we develop a method for excellently manipulating levitated femtoliter/picoliter droplets by a single focused laser. We show that the unique light-induced vapor flow in association with the interface morphology is responsible for creation and manipulation of levitated droplets. In particular, we demonstrate that the levitated droplets formed by this light method show extraordinary motility. The highly accurate two-dimensional labyrinth movement of the levitated droplets with designed trajectories above the free surface is easily realized by scanning the light. These results demonstrate that a single focused light can function as an "optical baton" to enable us to construct a wide variety of the long-sought precise manipulation systems for bioassays, pharmacy, and chemosynthesis.