Voltage is used to pull the pigment out of tiny reservoirs forming a small part of the viewable pixel area, spreading the pigment as a film behind the viewing substrate, with the display taking on the pigment's color. (visionect.com)
They found it took about 10 milliseconds for an oil droplet to expose the 200x600 µm2 pixel area. (phys.org)
A voltage applied across the aluminum and the ITO electrode pulls the ink out of the well and spreads it over the entire pixel area. (e-ink-info.com)