A two-joint robotic unit was developed to perform various tasks using a single unit. The unit is covered with a flexible plastic film and an insulating fluid, which makes it waterproof. A flexible film may limit the range of motion of a robotic unit. The robot packaging method, which is a method of packaging the internal components of a robot using the vacuum packaging technique, is used for plastic film covering. The effects of the film and the insulating fluid were experimentally clarified. Robot fingers, fish-like robots, and crawling robots were considered as application examples of the proposed robotic unit. These examples demonstrate that the robotic unit can work in contact with objects and in water.

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