Ultra-Soft and Stretchable Permanent Magnetic Elastomer Enables Wireless Vectorial Motion Monitoring Toward Neuromuscular Disorder Management

Abstract

Human motion monitoring is emerging as a critical strategy for early diagnosis and management of neuromuscular disorders. However, current sensors employed for motion monitoring typically rely on wired connections or rigid circuits, and mostly lack directional sensing capabilities. Here, we report a wireless and vectorial motion sensor based on a fully soft, hydrogel-based permanent magnetic elastomer (HPME) that transduces body movements into three-dimensional magnetic-field signals. The HPME resolves the long-standing trade-off between skin-like softness and high remanence by employing an Nd³⁺/Fe³⁺-coordinated, dual-crosslinked hydrogel network, achieving skin-like softness (9.86 kPa), >700% stretchability, and durable remanence (62.5 emu g⁻¹ for >10 days). Coupled with a miniaturized magnetic sensor, the HPME enables wireless detection of both motion magnitude and direction, demonstrated by monitoring Parkinsonian tremors and gait abnormalities and by precisely tracking cervical spine motion in four directions. This fully soft, stretchable, and highly responsive platform provides continuous, real-time motion monitoring, opening opportunities for earlier diagnosis, at-home assessment, and rehabilitation in neuromuscular disorders.