Magnetic Composites for Soft Robotics

Magnetic soft robotics offers a promising route to lightweight, untethered systems capable of complex and adaptive motion. This cumulative dissertation investigates how magnetic soft robotics can be advanced by co-designing materials, architecture, and sustainability from the ground up. It brings together three main contributions: (i) bioinspired morphing structures with large and adaptive deformations, (ii) muscle-inspired magnetic actuators with multifunctionality, and (iii) environmentally sustainable, recyclable magnetic composites for actuation and sensing. First, architected magnetic butterfly wings are fabricated from a thermoplastic polyurethane TPU/Nd-Fe-B composite using laser powder bed fusion (LPBF). The wings incorporate sub-millimeter flexural hinges, graded membrane regions, and pre-programmed magnetization patterns. Experiments and finite-element modelling show that large-angle folding, upstroke wing-clapping, and multistable morphing can be encoded purely through geometry and magnetization, without discrete joints or multi-material assemblies. Second, the same LPBF TPU/Nd-Fe-B platform is extended to muscle-inspired actuators that realize contraction-dominated motion. Zig-zag hinge architectures and radially expandable geometries are designed to shorten axially, lift loads many times their own weight, and perform gripping and anchoring tasks under low magnetic fields. By magnetizing pre-deformed structures, magnetization patterns are imprinted, enabling large reversible contractions and multifunctionality (load lifting, use in a crawling robot, and in-tube anchoring) within a single monolithic body. Third, the thesis introduces a sustainable magnetoactive material system based on recycled Nd-Fe-B microparticles embedded in a gelatin-glycerol/1,3-propanediol organogel. The composite combines high stretchability with robust magnetic response and is processed into thin-film robots and magnetoelastic sensing patches. Two closed-loop recycling routes are demonstrated: solvent-assisted matrix dissolution with magnetic particle recovery, and thermal remolding of composite fragments. Magnetic hysteresis measurements confirm that remanence and coercivity of the recycled particles remain largely stable over multiple cycles. Soft “flippy” and worm-like robots, as well as tactile and proximity sensors using pick-up coils and planar Hall sensors, show that meaningful robotic and sensing functions can be realized in a degradable, recyclable material framework. Across these three platforms, the dissertation establishes a coherent design philosophy: behaviour in magnetic soft robots can be programmed through the interplay of material constitution, architecture, and magnetization profile, while also addressing sustainability. Architected LPBF composites deliver optimal morphing and contraction, and gelatin-based organogels demonstrate that soft robotic functionalities can be embedded in circular material systems. Together, the results position this thesis for a new class of magnetic soft machines that are adaptive in form, capable in function, and responsible in their use of resources.