The interaction between fluids and electric fields drives a range of natural and technological phenomena, from raindrop disintegration in thunderstorms to inkjet printing, electrosprays, microfluidics, and fluid management in microgravity. The electrospray phenomenon—streams of charged droplets emitted from a liquid in an electric field—revolutionized mass spectrometry and earned John Fenn the 2002 Nobel Prize.
I became interested in this area after encountering a report of symmetry-breaking in droplets exposed to uniform electric fields. Our group’s research into the underlying nonlinearities revealed a host of new behaviors—such as tumbling and beating , vortex belts, and equatorially-emitted jets forming “Saturn rings” . Notably, we discovered that such streaming occurs even in low-conductivity fluids like oils and polymer melts, with promising implications for scalable droplet production in drug delivery and materials science. Most recently, we theoretically predicted that a pair of dissimilar droplets can exhibit self-propelled motion in a uniform electric field, forming a motile bound state. This phenomenon offers a new design principle for self-propelled — “swimming”– units in the field of active matter.
See Videos and these videos from the Gallery of Fluid Motion