This thesis deals with the characterization and dynamic modeling of the Ionic Polymer Metal Composite (IPMC) ‘artificial muscle’ materials, with the ultimate objective of creating a wearable exoskeleton comprising many of these polymers to assist the biceps muscle during operation. Using indigenously constructed data acquisition system designed for measuring small forces, displacements and currents, experiments were performed to characterize the behavior of two types of IPMCs. Environmental Robots, Inc. (ERI) was the initial vendor and its IPMC products required hydration for optimal performance. Virginia Polytechnic Institute and State University (Virginia Tech, VT) subsequently developed their innovative ionic solvent filled IPMCs that obviated hydration. Static tests were conducted to characterize force, displacement and current as a function of applied voltage. Dynamic tests were conducted to observe the frequency response of the material. Fatigue tests were performed on the ERI IPMCs to observe the change in behavior over time. Two indigenous fabrication methods, namely Thermal Vapor deposition and Sputtering, were investigated as plausible dry manufacturing techniques of IPMC.
The static tests showed that there was an inverse square relationship between the length of the strip and the tip blocking force. It was found that a fatigued ERI muscle had a bandwidth that was almost half that of a new muscle. It was also found that the VT IPMCs had a bandwidth that was almost half that of the ERI product. However, the ionic solvent filled VT IPMC ensured the repeatability of performance and generated increased force densities. Finally, an estimate on the number of IPMCs that would be required to create the exoskeleton was outlined. Feasibility issues were investigated with suggestions for future work.