OS0707 化学反応に伴う電極変形が及ぼすIPMCアクチュエータへの影響

Abstract

An ionic polymer-metal composite (IPMC) actuator, which consists of a thin perfluorinated ionomer membrane and electrodes plated on both surfaces, undergoes a large bending motion when a low electric field is applied across its thickness. IPMC actuators are lightweight and soft and can operate in solutions. They are thus promising for a wide range of applications including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. IPMC actuator with palladium electrodes shows tremendous large bending deformation at the applied voltage of over 2.5 V. To investigate the mechanism of this large deformation, we fabricated the actuator which consists of a thin polyamide membrane and electrodes plated on both surfaces. Polyamide membrane is not an electrolyte membrane and, thus, the deformation mechanism should be different from that of IPMC actuator. The tip displacements of these actuators were evaluated by applying voltage between plated palladium electrodes in an electrolyte. Also, we conducted cyclic voltammetry (CV) to identify chemical reactions on platted palladium electrodes. As the result, the polyamide membrane with palladium electrodes also showed the bending deformation over 2.5 V. Cyclic voltammetry analyses showed that the electrolysis of water and hydrogen formation occurred at cathode and the oxidation of palladium occurred at anode. Palladium electrodes absorbed hydrogen and expanded its volume at cathode. Therefore, it is concluded that this volume expansion causes the bending moment of membrane and assists the bending deformation of IPMC actuator with palladium electrodes.