3D printing of elastomer layers for dielectric elastomer transducers

In the continuously growing field of dielectric elastomers (DE) research is increasingly focusing on promising new production technologies with regard to reproducibility and flexibility. Challenges in production remain, especially the handling of thin elastomer films and applying the covering electrodes, which are in the range of several 10 and single-digit micrometers, respectively. Various fabrication processes, e.g. spin coating, blade casting, or sequential assembly of prefabricated elastomer films have so far been applied. Direct ink writing (DIW), or more precisely robocasting, is presented in this work for applying the elastomer layer. It is based on the extrusion of liquid elastomer in a wide viscosity range. This contribution presents printing of the elastomer layers by a DIW printer and evaluates the printing technology in terms of a fabrication method for dielectric elastomer transducers (DET). The requirements for 3D printing of DET are a homogeneous layer structure with low variation of the layer thickness, dimensional stability, and the avoidance of air inclusions. Considering these requirements, printing tests are conducted with the two-component silicone rubber ELASTOSIL RT 625 (Wacker Chemie AG, Germany). Elastomer layers are printed by varying the printing parameters, such as, the nozzle geometry and the printing speed. An optical inspection is implemented both to optimize the printing and to evaluate the result. In line with these objectives, the proposed process is evaluated by measuring the layer thickness and analyzing images of the printed elastomer layers. A minimum thickness for a single layer of approximately 40 mu m was achieved.