LAUSR

The traditional electroosmotic microfluidic mixers generally involve microelectrodes embedded on the inner wall of microchannel, which increases the difficulty of microchip processing and reduces the functional flexibility inevitably. In this paper, we report the development of a novel microfluidic mixer with straight microchannel based on the light-actuated oscillating electroosmosis in low-frequency sinusoidal AC electric field. The mixing performance is investigated by solving the coupled system of flow field, electric field and concentration field using finite element method. The formation mechanism of a pair of rotating vortices at both edges of the optical virtual electrode and the mixing mechanism of fluid samples are revealed. The effect of several key parameters including external applied potential, electric field frequency and inlet mean velocity on the mixing performance is also explored. The current technique provides a new method for efficient mixing of fluids in modern microfluidic analysis systems, and could potentially promote the comprehensive integration of functions, simplifying structure and reducing manufacturing costs of microchip.