Integrated micro fluidic system based on electrowetting
We fabricated an integrated micro fluidic system which functions by deliberately manipulating interfacial tension (Fig. 1). A distinctive characteristic of our system is the use of an array of adjacent, elongated, working electrodes and protruding polydimethylsiloxane (PDMS) open-flow channels. By changing the potential of the working electrode, wettability of the electrode surface changes and a liquid column can be transported from one end of an elongated working electrode to the other end. Transport of the liquid column can be altered without any valves by switching on the adjacent electrode in a given direction.
(Fig. 2) Transport of liquid through the flow channel. The solution was filled in the injection port (a), transported on the electrode 1 (b). When the potential of electrode 1 was switched on, the solution was mobilized into the flow channel. (c) By switching on the potential of electrode 2, part of the liquid column can then be transported to another flow channel. (d) The column could be split into another direction by applying a potential to electrode 3.
The flow velocity depended on the applied potential, i.e., the velocity could be altered by deliberate manipulation of the electrode potential. In addition, the flow velocity increased as the dimensions of the flow channel decreased. The applied voltage was less than 2 V, and the power consumption was in the order of tens of μW.
Fig. 1 
Fig. 2 