Dielectrophoresis of reverse phase emulsions

Reverse miniemulsions, emulsions of droplets of size 200 nm-1 μm of a polar liquid dispersed in an apolar continuous liquid phase, exhibit strong electrokinetic responses in low-frequency electric fields. The electrokinetic behaviour of a reverse miniemulsion, previously developed for use as electronic paper, has been investigated under static and flow conditions, in uniform and non-uniform electric fields. Results reveal that when using frequencies lower than 10 Hz strong aggregation of the droplets occurs. In uniform electric fields, under static conditions, droplets reversibly aggregate into honeycomb-like or irregular aggregates. Under flow conditions, droplets aggregate into approximately equidistant streams. In non-uniform electric fields the droplets reversibly aggregate in high-field regions, and can be guided along regions of high field strength in a flow. The potential of the technique for the formation of structured materials is discussed.