Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaves 100-104).Dielectric elastomer (DE) actuators are an emerging class of polymer actuation devices. They exhibit large strains and have high force and energy densities. They can be designed in a variety of geometries and are inexpensive to manufacture. Currently, the use of DE Actuation is limited because quantitative design information is incomplete and the complex phenomena governing their performance have not been fully characterized. In this study, several such issues are investigated both experimentally and analytically. The actuators designed for this research function as binary actuators, that is, they operate between two set states, OFF and ON. Performance of the actuators is predicted based on theoretical analysis and the results are compared to experimental results. Improvement of fabrication methods and determination of optimum design parameters have been experimentally determined. Since DE actuators can be constructed out of polymers and without any ferromagnetic materials, they can potentially be used in a Magnetic Resonance Imaging (MRI) machine, which has strict compatibility requirements that limit the use of certain materials. MRI is a powerful and effective medical diagnostic tool, but treatment is limited because of the confined space and compatibility issues. It has been well recognized that its value would be increased if it were possible to physically manipulate objects within the MRI machine during imaging, but conventional manipulation systems cannot operate within an MRI due to the incompatibility of ferromagnetic materials. Binary DE actuators eliminate the need for conventional electromagnetic actuators and their associated controlling electronics. This inherent compatibility suggests that a new class of MRI treatment devices(cont.) is possible. Potential applications for use in the MRI environment are introduced, and prototypes for illustrating these applications are fabricated. One such application, a reconfigurable RF coil for flexible imaging capabilities, proves that not only are DE actuators and MRI compatible, but that they can significantly enhance imaging capabilities.by John D. Vogan.S.M
