Hierarchical Design and Interfacial Work Function Modulation Endow Fe ₂ O ₃ /SnO ₂ /Carbon Foam Improved Sensibility for Rehabilitation Training

Abstract The escalating demands for continuous, accurate, and non‐invasive monitoring of physiological motions in modern rehabilitation medicine have significantly propelled the development of high‐performance flexible sensors with sufficient sensitivity to detect weak signals and suitable detection range to accommodate wide amplitudes. Herein, 3D Fe ₂ O ₃ /SnO ₂ /carbon foams (Fe ₂ O ₃ /SnO ₂ /CFs) with gradient microstructure and tunable interface work function are constructed. The n–n Fe ₂ O ₃ /SnO ₂ heterojunction facilitates interfacial charge transfer, substantially reducing the initial resistance ( R _0↓ ). Concurrently, within carbon foam, the vertically‐grown hierarchical architectures composed of Fe ₂ O ₃ micro‐cones with gradient stiffness and surface‐distributed SnO ₂ nanoparticles synergistically generate stress concentration at Fe ₂ O ₃ tips and the proliferation of conductive pathways upon compression, thereby amplifying resistance variation ( ΔR _↑ ) for improved sensitivity and extended detection range. Capitalizing on these structural advantages, Fe ₂ O ₃ /SnO ₂ /CF‐based flexible pressure sensor exhibits an elevated sensitivity of 479 kPa ⁻¹ , a wide sensing range of 0–50 kPa, and exceptional stability. Furthermore, smart insoles integrated with Fe ₂ O ₃ /SnO ₂ /CF sensors enable real‐time gait analysis, demonstrating its capability to give guidance on personalized rehabilitation training and therapeutic management through precise assessments of neurological and traumatic disorders.