Polysiloxane Inks for Multimaterial 3d Printing of High‐Permittivity Dielectric Elastomers

Abstract

Dielectric elastomer transducers (DET) are promising candidates for electrically‐driven soft robotics. However, the high viscosity and low yield stress of DET formulations prohibit 3D printing, the most common manufacturing method for designer soft actuators. DET inks optimized for direct ink writing (DIW) produce elastomers with high stiffness and mechanical losses, diminishing the utility of DET actuators. To address the antagonistic nature of processing and performance constraints, principles of capillary suspensions are used to engineer DIW DET inks. By blending two immiscible polysiloxane liquids with a filler, a capillary ink suspension is obtained, in which the ink rheology can be tuned independently of the elastomer electromechanical properties. Rheometry is performed to measure and optimize processibility as a function of filler and secondary liquid fraction. Including polar polysiloxanes as the secondary liquid produces a printed elastomer exhibiting a four‐fold permittivity increase over commercial polydimethylsiloxane. The characterization and multimaterial printing into layered DET devices demonstrates that the immiscible capillary suspension improves the processability of the inks and enhances the properties of the elastomers, enabling actuation of the devices at comparatively low voltages. It is anticipated that this formulation approach will allow soft robotics to harness the full potential of DETs.

Nozzle Innovations That Improve Capacity and Capabilities of Multimaterial Additive Manufacturing

“…One AM method that is particularly straightforward to adapt for multimaterial deposition is layer-by-layer direct ink writing (DIW). The simplest conceivable adjustment is to manually swap nozzles loaded with different materials during fabrication. , For example, consider 3D printing of a multilayered dielectric elastomer actuator − which requires alternating layers of elastomer and conductive electrode ink to be patterned over long ranges (Figure ). In layer-by-layer DIW, the electrode ink (gray ink in Figure ) is loaded into a barrel or syringe and fed into a single conical-shaped nozzle, which is mounted on a 3D-printing arm that can raster in Cartesian coordinates.…”