3D printing of electro-ionic artificial muscles with rapid, large, and programmable deformations

Ionic-polymer metal composites (IPMCs) actuators are smart materials that have garnered increasing attention in the field of soft robotics due to their large bending deformation and rapid response to low operating voltages. However, conventional fabrication methods, such as solution-casting, have inherent limitations, including long fabrication times, simple geometries, and a single deformation mode. This study develops a polylactic acid (PLA)-reinforced perfluorosulfonic acid resin (PFSR) composite filament for fabricating IPMC actuators with programmable deformation via fused filament fabrication (FFF) 3D printing. Incorporating PLA into soft PFSR filaments improves printability and allows the printed parts to be reshaped into desired geometries that are difficult to print directly. The 3D-printed actuator exhibits superior actuation performance, with a bending angle of 169° (5.72% bending strain) under a DC voltage of 3 V and a swing speed of 56° s −1 at 3 V, 1.0 Hz sinusoidal voltage. Interestingly, its shape morphing can also be pre-programmed to switch between bending and helical deformation by controlling printing parameters. These deformations can be predicted by the proposed finite element numerical method. As proof-of-concept demonstrations, various intriguing applications, including a U-shaped structure, a spiral structure, a bionic flower, and a microarchitecture for robotic metamaterials, are fabricated, revealing the potential of the 3D printing method in the realms of stimuli-responsive materials, robotic applications, biomimetic devices, and beyond.