Electrokinetic motion of a micro oil droplet under a glass slide

Abstract

Electrokinetic motion of a micro oil droplet beneath a glass slide was experimentally investigated in this paper. The micro oil droplets were released under the glass slide in an aqueous solution and the motion along the glass slide was measured by a microscope. The experimental results indicate that while the electrokinetic mobility increases with the applied electric field, it decreases with the oil droplet size and the ionic concentration of the aqueous solution, respectively. By changing the zeta potential of the glass-liquid interface using polybrene coating from negative to positive, the direction of the electrokinetic mobility is reversed and the absolute value of the electrokinetic mobility increases significantly. Finally, pH effects were also investigated, and it was found that the electrokinetic mobility of the droplets reaches a maximum at pH = 6∼8.

Keywords: Electrokinetic motion; Glass slide; Oil droplets; Thin film.