Interplay of electrokinetic effects in nonpolar solvents for electronic paper displays.

Electronic paper displays rely on electrokinetic effects in nonpolar solvents to drive the displacement of colloidal particles within a fluidic cell. While Electrophoresis (EP) is a well-established and frequently employed phenomenon, electro-osmosis (EO), which drives fluid flow along charged solid surfaces, has not been studied as extensively. We hypothesize that by exploiting the interplay between these effects, an enhanced particle transport can be achieved. In this study, we experimentally investigate the combined effects of EP and EO for colloidal particles in non-polar solvents, driven by an electric field. We use astigmatism micro-particle tracking velocimetry (A- μ PTV) to measure the motion of charged particles within model fluidic cells. Using a simple approach that relies on basic fluid flow properties we extract the contributions due to EP and EO, finding that EO contributes significantly to particle transport. The validity of our approach is confirmed by measurements on particles with different magnitudes of charge, and by comparison to numerical simulations. We find that EO flows can play a dominant role in the transport of particles in electrokinetic display devices. This can be exploited to speed up particle transport, potentially yielding displays with significantly faster switching times. Interplay of electrokinetic effects : Driven by the applied electric field, both electro-osmosis (EO, top left), which drives a flow along the surfaces of the fluidic cell, and electrophoresis (EP, top right), which drives a migration of particles relative to the background liquid, occur in our system. A typical example of the resultant particle velocity field (bottom) illustrates the important role of EO on particle transport in the fluidic cell. • Studied electrokinetics of particles in nonpolar solvent using astigmatism micro-PTV. • Both electrophoresis (EP) and electro-osmosis (EO) play important roles. • Combination of EO and EP could be exploited in faster switching e-paper displays. [ABSTRACT FROM AUTHOR]