Challenges to the application of IPMC as actuators of planetary mechanisms

Ion-exchange polymer membrane metallic composites (IPMC) are one of the electroactive polymers (EAP) that were shown to have potential application as actuators. The recent introduction of perfluorocarboxylategold composite with tetra-n-butylammonium and lithium cations instead of sodium made the most significant improvement of the material's electroactivity. Under less than 3 volts, such IPMC materials were shown to induce bending beyond a complete loop. The bending characteristic of IPMC offered an attractive actuation capability for a dust wiper in planetary applications and it was explored for the Nanorover's infrared camera window of the MUSES-CN mission. This joint NASA and the Japanese space agency mission, is scheduled to be launched from Kagoshima, Japan, in January 2002, to explore the surface of a small near-Earth asteroid. The application of EAP at space conditions posed a great challenge due to the harsh operating conditions that are expected and the critical need for robustness and durability. Several issues that are critical to the application of IPMC were addressed including operation in vacuum and low temperatures, as well as the effect of the electromechanical characteristics of the IPMC on its actuation capability. Highly efficient IPMC materials, mechanical modeling, unique elements and protective coatings were introduced to enhance the applicability of this EAP material. However, critical issues were identified that hamper the transition of IPMC from being considered for practical applications at this stage.