3D Printing of IPMC Actuators Based on the Direct Assembly Method

Abstract

Ionic polymer metal composites are a type of electroactive polymers, they are composed of an ionomer membrane sandwiched between two conducting high surface area electrodes. They act as an actuator under the application of a relatively small applied electric voltage in the order of 1 to 4V, producing large strains compared to other actuators. The middle membrane acts as an eclectic insulator that allows ions to move from one electrode to the other. The negatively charged high surface area electrode attracts the positively charged mobile cations resulting in actuation. IPMCs also operate in sensing mode by generating electricity when subject to mechanical deformations. This versatility in operation makes them good candidates for a number of complex applications including biomimetics, micro-robotics, and medical catheters. These different application demand complex geometries and high level of performance. The electrode morphology has been proven to play a critical role in the performance of IPMCs. In this thesis, the process of 3D printing the IPMC along with the electrodes using FDM 3D printing is investigated. Our method will enable the 3D printing of both: the Nafion insulating center layer, and a Ruthenium Dioxide-Nafion mixture composing the high surface area electrode. The electrodes performance will be evaluated against the traditional impregnation reduction method for electrode plating applied to a 3D printed membrane. Also, the performance of a membrane made by hot-pressing Nafion pellets, a traditional Nafion membrane fabrication method, will be used to validate the 3D printing process. The 3D printed electrodes achieved a strain of 3.71E-4 which was lower than the strain of impregnation reduction method at 1.14 E-3. This was attributed to excessive flaking and poor mixing of the Ruthenium Dioxide particles in the polymer matrix.