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 300nm 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 0.2zeptoJ(0.05kBT) precision, thus providing experimental tools for fundamental studies.