Modulating Stiffness and Shape of a Soft, Textile‐Based Structure Through Glass Transition of a Conductive Phase‐Changing Polymer

The challenges of operating robots in natural, highly variable, and diverse physical environments demand equally variable solutions. Following a flexible design approach from soft robotics, a variable stiffness structure with shape morphing and shape memory capabilities made from layered textiles and 3D printing material is developed. The stiffness change of the central conductive PLA (cPLA) is achieved electrically via Joule heating. Fabrication of multiple segment surfaces from the textile materials allows for direct printing of cPLA, which maximizes the electrodes' contact area. The material's variable stiffness is then used to modulate the structure's bending behavior and actively change its shape (shape morphing) while preserving shape memory behavior. To achieve this, models for stiffness change, heat transfer, and shape morphing are introduced and tested experimentally. The design presents a new method for achieving variable stiffness of 2794 Nmm² in small segments of soft, deformable structures, using widely available materials and simple manufacturing methods. Furthermore, the structure's design enables shape morphing and shape memory.