EPD

In EPD-Ink, charged nanoparticles with an identical signal are dispersed uniformly in a low dielectric medium with different colors. When an electric field is applied, the nanoparticles move either top or bottom of the fluid depending on the polarity of electric field created by the external power source, which in turn leads to color switching. 
EPD has an excellent outdoor visibility and low power consumption compared to emissive displays such as the Liquid Crystal Display (LCD). Hence, it is appropriate for outdoor public display applications, including electronic signage and e-Books.