Rotation of a microvalve near conductive electrodes via induced-charge electrophoresis.

The development of a high-speed microactuator in water is difficult because of hydrodynamic resistance and the lack of the knowledge of complex electrostatic problems combined with flow fields and ion dynamics. Previously, to overcome these problems, we proposed rotary microvalves in water using hydrodynamic force due to induced-charge electrophoresis (ICEP). In this study, by using an elliptical conductive carbon element fabricated by the pyrolysis of a photoresist film coated with gold, we experimentally demonstrate that microvalves can rotate near conductive electrodes. Namely, by numerically analyzing video data, we show the time evolution of the rotation angle, the flow field, and the center position of the microvalve. Further, we compare them with the theoretical results and find that they are in good agreement qualitatively. In the future, by using ICEP valves as a latch device, we can significantly improve the size and processing speed of a fluidic integrated circuit.