This is a process by which the
surface tension of a
liquid can be changed electrically. It is extremely useful in
microfluidics, and is becoming useful in
electronic ink and
nanotech battery applications.
By changing the surface tension of a fluid by external non-chemical means, the fluid can be made to flow more easily along paths desired. In microfluidic applications such as lab-on-a-chip analysis, microscopic drops of liquid move through tiny capillaries on the chip through various reagents and/or sensors to perform the various tests. In electronic ink, one method of changing the state of the ink from one color to another is by using an applied voltage to change the ink's surface tension, floating or sinking material suspended within it. In a nanotech battery, a voltage would control whether the electrolyte stays separate from the electrodes, permitting long-term storage, or flows among the electrodes, energizing the battery.
rootbeer277 asks the very important question, "Where would the electricity come from to turn the battery on?" As the actual current required to change the state of the liquid on a small portion of the cell is very small, a piezoelectric switch or a small capacitor would suffice to start the process.
Update: now Philips is using this to make displays.