Micro-fabricated Ionic conductive polymer film actuators for aqueous micromanipulation

The development of a novel Ionic Conductive Polymer Film (ICPF) micro actuator is presented in this paper. A commercial solution from Dupont Co. (Nafion SE-5012) was used to prepare ∼ 0.2μm thick ionic conductive polymer film. Cantilever structures composed of Au/Nafion/Au film layers were microfabricated on silicon substrate based on photolithographic technique. The structure was released by etching sacrificial aluminum in phosphoric acid at room temperature. The smallest actuators fabricated were 200μm wide, 400μm long and 0.2μm thick We have proved that these actuators could be fully actuated in water at ∼ 3V DC voltages. In addition, another interesting actuation behavior of the micro actuator was observed during fabrication. The actuators tended to curl whenever contacted with water during sacrificial release process. The process reversed instantaneously with the immersion in acid. We suggest that this phenomenon is due to the different volume expansion of Nafion in different medium. We are currently studying the consistency of the actuation behaviors. In the future, the design of the structures will be modified to realize precise control of actuation behavior and practical applications.