Rheologically Engineered 3D-Printed Highly Loaded Magneto-Dielectric Absorbers for Device-Level Electromagnetic...

Highly loaded magneto-dielectric composite systems are promising for achieving strong electromagnetic loss and structural design flexibility, yet their processability and geometric controllability remain extremely challenging. Herein, a rheologically engineered direct ink writing (DIW) 3D printing strategy is developed. Graphene (Gr) is introduced to reconstruct the particle-loading network, which synergistically improves the ink's yield behavior, shear-thinning property, structural recovery, and a magnetic-dielectric synergistic loss system is constructed with carbonyl iron powder (CIP). The critical CIP content (~ 84.06 wt%) is determined by the yield model, and a tunable Gr/CIP (GC) composite ink is obtained. The correlation among rheological response, geometric fidelity, and temporal stability is established, enabling high-fidelity 3D-printed gradient honeycomb structures. The rationally designed 3D-printed GC honeycomb (GCH) absorber achieves an effective absorption bandwidth of 18 GHz-4 THz, with an RL_min of - 84.30 dB at a thickness of 2.6 mm. When integrated into device-level terahertz reconfigurable intelligent surfaces (RIS), the GCH absorber contributes to a ~ 3.3 dBi main lobe gain enhancement, 1.9-3.3 dB sidelobe suppression, and a ~ 58% reduction in reflection beamwidth, showing excellent electromagnetic compatibility performance for communication, imaging, and radar. This work offers a practical strategy for the structural fabrication and device integration of high-load magneto-dielectric synergistic absorbers.