**1. Introduction**

Magnetic fluid has unique properties[1], by which it can, not only be attracted to, but also solidified by magnets. Many researchers have proposed useful applications for these properties, such as in dampers, sensors, actuators [2][3] and medical applications[4]-[6]. J.Furusho et al. [7] developed MR-Fluid Actuator, controlled it by use of torque Feedback. He also developed 6-DOF Rehabilitation System driven by ER-Actuator[8]. The functional fluid has performed well in clinical use. However, as all Magnetic fluids have a greater specific gravity than liquids like water, the applications are restricted.

This chapter presents a new type of magnetic fluid and the rotational drive with simple magnetic field. This chapter consists of two sections.

The first section describes the development of a unique magnetic fluid and the proposal of a driving principle by use of the magnetic fluid. We have developed a lighter fluid than liquid, mixed it with liquid, and created a new impetus in this research. We have proposed a driving principle and developed the verification models and the generator of magnetic field. It became clear that our proposed driving principle results from collision of the magnetic particles to the outer cover, deformation of the whole form of magnetic particles and movement of the center of gravity.

The second section describes an advanced translation drive that produces non-slipping motion in soft and closed environment by use of the magnetic fluid. New movement principle of the robot, which has a soft and deformable body that can move through a confined space is proposed. The mechanism of a toy water snake is applied to this principle. Magnetic particles inside the water balloon are affected by the external magnetic field and push the inner side of a balloon to the direction of a magnetic field. We construct an experimental model to verify the proposed principle, the sliding movement is measured using the model.

©2012 Nokata, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0),which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
