The digital revolution has come to microfluidics. In digital microfluidics
(DMF), discrete droplets are manipulated by applying electrical fields to an
array of electrodes. In contrast to microchannels, in DMF each sample and
reagent is individually addressable, which facilitates exquisite control over
chemical reactions. Here, we review the state-of-the-art in DMF, with a
discussion of device formats, actuation physics, and biological and nonbiological
applications. Along the way, we identify the key players in the field,
and speculate on the advances and challenges that lie ahead. As with other
fronts in the digital revolution, there have been and will be unexpected
developments as DMF matures, but we posit that the future is bright for this
promising technology.