On-chip manipulation of levitated femtodroplets

We report diamagnetic levitation of droplets and∕or particles of pico–femtoliter volume and demonstrate their on-chip storage and high precision manipulation (translation, merging, assembling and rotation). We also demonstrate a levitation based microfluidic processor to process droplets∕particles with up to a billion times smaller volume than in typical microfluidic devices. The levitated particles can be positioned with up to $300\mathrm{nm}$ accuracy and precisely rotated and assembled, providing a different physical approach for micro-electro-mechanical systems. Force can be applied to the droplets∕particles via magnetic, electric, and gravitational fields with up to femto-Newton accuracy, and potential energy can be controlled with up to $0.2\mathrm{zepto}\mathrm{J}\left(0.05k_{B}T\right)$ precision, thus providing experimental tools for fundamental studies.