Untethered selectively actuated microwave 4D printing through ferromagnetic PLA

Abstract

We present a novel four-dimensional (4D) printing technique that uses microwave radiation to achieve non-contact actuation on thermal activated shape-shifting structures. By integrating dielectric materials into a shape memory polymer (SMP) structure at specific locations, microwave radiation can be used to actuate the 4D printed object. The proposed method is demonstrated using a Fused Deposition Modeling (FDM) printer and thermoplastic filaments. In addition to existing shape-shifting deformations, this technique adds novel capabilities such as selective region heating, precise multi-step actuation, remote actuation, and reduced heating time. To study the behavior of the proposed method, a coupled mathematical model for electromagnetic waves, heat transfer and solid mechanics is simulated using finite element methods and is validated by comparing with experimental results. The test cases presented in this paper demonstrate how selective heating provides additional control over existing 4D printing designs and showcases a new generation of shape-shifting structures that are multi-layered and capable of being stimulated by multiple stimuli. • A novel approach that uses microwaves to activate 4D prints to achieve selective heating and actuation without contact. • Multiphysics simulation that models the heating behavior accurately. • Example test cases for demonstrating benefits of selective heating as well as compatibility with other methods.