Droplet manipulations by dielectrowetting: Creating, transporting, splitting, and merging

This paper presents four droplet operations (creating, transporting, splitting and merging of droplets) actuated by dielectrowetting (not electrowetting), which fundamentally constitute a backbone of droplet-based digital microfluidics. These operations are successfully achieved for both non-conductive (dielectric) and conductive (DI water with/without surfactant) fluids in an open environment on a single plate. All these features are attributed to the dielectrowetting nature of superspreading. By contrast, electrowetting works only with conductive fluids, commonly in the two-plate (hundreds microns gap) channel environment. Particularly, splitting and creating by electrowetting have never been realized on a single plate. As for the present device, these successful operations significantly enhance digital microfluidics to work for a wide range of fluids, to simplify the required physical structures, and to increase the handing fluid volumes (otherwise limited by the two-plate gap).