Control of electro-osmostic flow by light

The author introduce a technique for the optical control of electro-osmosis. One wall of the microfluidic channel is formed by a photoconductive material. Illumination of the photoconductor results in a local drop of the electric field in the microchannel, reducing the electro-osmotic driving force. Fluid flow can be effectively modulated by light utilizing this effect. They verified the phenomenon in linear channels and further developed the method by building a Y junction, an optically controlled microfluidic switch. This unit is the basis of more complex flow patterns: it demonstrates the feasibility of dynamic optical control of microfluidic devices. (c) 2006 American Institute of Physics.