Additive manufacturing of morphing structures with multi-stimuli activation capabilities

Shape memory polymers (SMPs) are capable of returning from a deformed state to their original shape when exposed to external stimuli such as heat, light, or electricity. When integrated with flexible electronics, SMPs enable the development of reconfigurable and adaptive structures that can dynamically change shape in response to their environment. This study employs material extrusion and fused filament fabrication to advance the production of SMP-based morphing structures. Conductive silver traces were embedded within a polylactic acid (PLA)/thermoplastic polyurethane (TPU) SMP matrix to enable shape recovery via Joule heating, in addition to direct thermal activation. The use of SMPs in various colors further enables light-responsive morphing. The printing process was studied to enhance the topographic quality of both the PLA/TPU matrix and silver traces. Thermo-mechanical characterization of the printed SMP was conducted to evaluate its mechanical strength, recoverable strain, and glass transition temperature. Functional prototypes were fabricated to demonstrate morphing in response to heat, light, and electrical inputs. Eventually, a multiphysics finite element model was developed to predict their deformation under electrical stimulation.