A study on the slip velocity on a pair of asymmetric electrodes for AC-electroosmosis in a microchannel

作者：Wang Yangyang; Suh Yong Kweon; Kang Sangmo^*

来源：Journal of Mechanical Science and Technology, 2009, 23(3): 874-884.

DOI：10.1007/s12206-009-0104-2

• AC-electroosmosis
• Effective Stem-layer thickness
• Ion adsorption
• Slip velocity
• Particle image velocimetry (PIV)

In numerical studies on microscale electroosmotic flows, the electric double layer (EDL) effect is usually predicted by solving the traditional Navier-Stokes equation subjected to the slip velocity induced by the electric-charged wall as a boundary condition. Recently, Sub and Kang (Physical Review E 77, 2008) presented the asymptotic Solutions of the ion transport equations near a polarized electrode under the action of an AC field, and then proposed a new theoretical model of the slip velocity on the electrode considering the ion adsorption effect. In the present paper, we apply the model to a two-dimensional AC-electroosmotic flow in a microchannel to calculate the slip velocity on a pair of coplanar asymmetric electrodes embedded on the bottom wall, and then experimentally measure the slip velocity using the micro-PIV technique to validate the theoretical model. Comparison shows an excellent overall match between the theoretical and experimental results, except for on the narrow electrode at low frequencies. Next, we numerically perform parametric studies regarding the AC frequency, effective Stern-layer thickness and ion adsorption effect to further understand the characteristics of the AC electroosmotic flow. Results show that, as the frequency increases, the slip velocity also increases. In addition, the velocity decreases with increasing either Stem-layer thickness or ion adsorption effect.

• 出版日期2009-3