A pediatric robotic thumb exoskeleton for at-home rehabilitation

Abstract

Purpose – Pediatric disorders, such as cerebral palsy and stroke, can result in thumb-in-palm deformity greatly limiting hand function. This not only limits children's ability to perform activities of daily living but also limits important motor skill development. Specifically, the isolated orthosis for thumb actuation (IOTA) is 2 degrees of freedom (DOF) thumb exoskeleton that can actuate the carpometacarpal (CMC) and metacarpophalangeal (MCP) joints through ranges of motion required for activities of daily living. The paper aims to discuss these issues. Design/methodology/approach – IOTA consists of a lightweight hand-mounted mechanism that can be secured and aligned to individual wearers. The mechanism is actuated via flexible cables that connect to a portable control box. Embedded encoders and bend sensors monitor the 2 DOF of the thumb and flexion/extension of the wrist. A linear force characterization was performed to test the mechanical efficiency of the cable-drive transmission and the output torque at the exoskeletal CMC and MCP joints was measured. Findings – Using this platform, a number of control modes can be implemented that will enable the device to be controlled by a patient to assist with opposition grasp and fine motor control. Linear force and torque studies showed a maximum efficiency of 44 percent, resulting in a torque of 2.39±1.06 in.-lbf and 0.69±0.31 in.-lbf at the CMC and MCP joints, respectively. Practical implications – The authors envision this at-home device augmenting the current in-clinic and at-home therapy, enabling telerehabilitation protocols. Originality/value – This paper presents the design and characterization of a novel device specifically designed for pediatric grasp telerehabilitation to facilitate improved functionality and somatosensory learning.