AC electrokinetic phenomena over semiconductive surfaces: effective electric boundary conditions and their applications

TL;DR

This paper develops new boundary conditions for AC electrokinetic phenomena over semiconductive surfaces, enabling better analysis of induced flows and potentials in systems with leaky dielectric materials under AC fields.

Contribution

The paper introduces electrokinetic boundary conditions that account for both polarization and conduction effects at semiconductor-electrolyte interfaces under AC fields.

Findings

Flow circulations are present around semiconducting cylinders.

Circulation strength increases with lower AC frequency.

Higher conductivity enhances flow circulation.

Abstract

Electrokinetic boundary conditions are derived for AC electrokinetic (ACEK) phenomena over leaky dielectric (i.e., semiconducting) surfaces. Such boundary conditions correlate the electric potentials across the semiconductor-electrolyte interface (consisting of the electric double layer (EDL) inside the electrolyte solutions and the space charge layer (SCL) inside the semiconductors) under AC electric fields with arbitrary wave forms. The present electrokinetic boundary conditions allow for evaluation of induced zeta potential contributed by both bond charges (due to electric polarization) and free charges (due to electric conduction) from the leaky dielectric materials. Subsequently, we demonstrate the applications of these boundary conditions in analyzing the ACEK phenomena around a semiconducting cylinder. It is concluded that the flow circulations exist around the semiconducting cylinder and are shown to be stronger under an AC field with lower frequency and around a cylinder with higher conductivity.