4D-Printed soft exoskeleton for grasping assistance

• A dynamic adaptation design method combining reverse engineering and 4D printing. • Pre-programmed deformable unit finger structure. • Heterogeneous integrated micro drive system. Hand exoskeletons have significant potential for restoring functional grasping ability in patients with neuromuscular injuries, yet traditional designs have long been limited by bottlenecks such as high stiffness and bulky mechanical components. In this study, an innovative scheme of soft exoskeleton based on 4D printing technology is proposed to achieve personalized customization of target patients through material-structure-driven collaborative design. The exoskeleton adopts shape-memory polymer (PolyMaxPLA) to build a dynamic programmable structure, and achieves patient-specific integrated molding through thermal activation (75 °C) improves the mechanical drive components and assembly processes required for traditional exoskeletons, with a unit knuckle weight of 2.3 g-3.2 g (total weight of the full glove including the drive system is 135 g). Finite Element Analysis (FEA) has verified the excellent mechanical properties of the exoskeleton, maintaining a safety factor of 3.96 at a gripping force of 10 N. Fatigue simulations predict a minimum service life of 14.2 k cycles. Functional validation demonstrates comprehensive task coverage spanning thumb flexion, multi-digit grasping, and precision pinching. This study proposes a novel design paradigm for resolving the stiffness-flexibility paradox in wearable rehabilitation devices. The print-and-use manufacturing strategy and dynamic self-adaptation mechanisms establish new pathways for advancing neurorehabilitation toward personalized and intelligent therapeutic implementation.