A Hand Exoskeleton With 3D-Printed Compliant Mechanisms to Assist Grasping

Hand exoskeletons have been developed to assist the grasping of people with hand dysfunction in daily activities and rehabilitation. However, there are challenges with weight, portability, and the use of the hand's tactile sensation and friction. This paper reports on a lightweight, portable, flexible hand exoskeleton to assist grasping. It features a 3D-printed compliant mechanism with anisotropic flexibility and a tendon acting as a rack gear driven by a small motor to flex it. These features enable portability and a total weight of 177 g (The exoskeleton alone weighs 73 g). Restraint on the ventral side of the fingers and palm is kept to a minimum to exploit the hand's tactile sensation and friction. The grip forces when wearing the exoskeleton were 2.39 N for the power grip and 1.80 N for the pincer grip. The pick-and-place tests with four healthy participants showed that the exoskeleton could assist in grasping objects weighing less than 200 g. The exoskeleton could assist in grasping daily necessities such as a plastic bottle, ball, and plate. The lightweight and portability of the flexible exoskeleton demonstrated its potential for daily use.