Electronics-free pneumatic robots for Post-Stroke rehabilitation

Pneumatic rehabilitation robots show a promising approach for restoring motor functions in individuals with post-stroke spasticity and muscle weakness. However, conventional systems rely on bulky, complex mechatronic components for pressure regulation, limiting their portability, compatibility, and real-world deployment. Here, we introduce an electronics-free pneumatic rehabilitation robot that leverages physical intelligence (PI) to simplify control strategy and reduce costs. Central to our design is a mechanically oscillating valve, termed a metacap, constructed from a spherical shell with metamaterial architecture. By strategically tuning geometric parameters and material stiffness, the metacap transforms a constant input pressure into self-regulating, periodic inflation-deflation cycles. This enables pneumatic actuators to drive rhythmic finger flexion and extension across a wide bending range, accommodating diverse rehabilitation requirements related to spasticity and muscular weakness. Operational space experiments demonstrate the robot's adaptability, enabling finger movements with a range of motion comparable to that of a human hand. Clinical evaluations reveal alleviated hand and upper-limb spasticity, along with improved upper-limb motor function. Our PI-based design provides a scalable, low-complexity framework for next-generation rehabilitation devices, particularly suited to resource-constrained clinical settings and home-based therapy. © 2025 The Authors.