Valve-less micro fluidic transport via deliberate electrochemical manipulation of surface tension

An on-chip microfluidic system was constructed which transports a liquid column in a micro flow channel by deliberately controlling interfacial tension by electrode potential. It features a low driving voltage and power consumption. The system consists of a flow channel and a four-electrode system with two gold working electrodes. The working electrode patterns were formed on the bottom and walls of the flow channel. In an independent structure, the flow channel was closed and the working electrode patterns were formed so that they surrounded the flow channel on all sides. By setting the potentials of the working electrodes at appropriate values, the interfacial tension between the electrolyte solution and the working electrodes changed, resulting in a movement of the liquid column. The displacement depended on several factors including the geometry of the flow channel and the concentration of electrolyte.