Development of a 3D-Printed IoT-Enabled Finger Exoskeleton for Fine Motor Training

There are currently lack of assistive devices connected to Internet of Things (IoT), which enables precise real-time, and remote control and monitoring of the patients during finger fine motor rehabilitation. This study aimed to enhance existing hand therapy tool by developing a portable, adjustable, lightweight (500 g) and remotely controllable finger exoskeleton to enhance fine motor training of fingers. The exoskeleton was designed to assist in actuating flexion-extension movements of all 4 fingers and thumb in the metacarpophalangeal (MCP) joint, and grasping movement. The mechanical frame was designed using computer-aided design (CAD) software and additive manufactured with polylactic acid (PLA) filaments. The functional components include inertial measurement units (IMUs) that measure the range of motion (ROM) of the index finger and thumb; servo motors that enable precise rotary actuation in performing specific finger and thumb movements; a microcontroller as the control system; velcro straps and an adjustable wrist guard provide flexibility to accommodate various finger diameters and wrist sizes; and a simple IoT user interface that aid the therapists in monitoring rehabilitation progress of individual patient during home-based rehabilitation, as well as controlling the exoskeleton remotely. This exoskeleton could perform 4 fingers flexion/extension and thumb flexion/extension on participants with various hand sizes (15.5 cm to 18 cm) consistently with a low standard deviation (SD < 10), and it could aid on users' grip strength with a percentage increase of 16.86% and 14.09% of index finger and thumb respectively. Experimental outcomes showed that the exoskeleton was able to acquire, display and store relevant data accurately when assisting participants to perform repetitive flexion/extension movement and practice grasping on objects of various shapes and sizes. This proof of concept demonstrated the exoskeleton can assist and has the potential to improve the effectiveness of fine motor trainings in finger rehabilitation, besides providing more convenience to the users and therapists.