Wearable Soft Actuator for Restoring Finger Adduction-Abduction

Finger adduction and abduction are essential for daily activities such as typing, grasping, and manipulating small objects, yet these movements are often impaired by neuromuscular disorders or injuries, significantly reducing quality of life. Conventional rehabilitation strategies frequently overlook lateral finger motions or lack the adaptability to accommodate the full range of movement. To address this limitation, we present a portable, low-cost, and user-friendly soft pneumatic rehabilitation device specifically designed to restore finger adduction and abduction. The elastomer-based actuator, dorsally mounted across the phalanges, enables controlled MCP joint rotation through regulated inflation-deflation cycles while ensuring natural alignment and automatic return to the neutral position. In contrast to existing systems that restrict movement by positioning actuators between fingers, the proposed design prioritizes comfort and physiological motion. Experimental validation with ten healthy participants demonstrates an average angular displacement of 36 degrees, reliable inflate-hold-deflate cycle completion within 5 seconds, and peak lateral force generation of 8 N at a stable operating pressure of 80 kPa, sufficient to induce finger motion without discomfort. With position feedback integrated into an on-off control scheme, the device achieves consistent and repeatable motion patterns suitable for unsupervised rehabilitation. By targeting lateral finger motion recovery, the proposed system fills a critical gap in hand therapy and represents a practical alternative to rigid exoskeletons, advancing wearable rehabilitation technology.