Finger rehabilitation system with double action and two degrees of freedom

Abstract

Currently, most of today’s designs of rehabilitation gloves for patients with motor impairments on their fingers focus only on assisting the hand’s opening motion (single action gloves). Most of the time, these gloves need to be operated on with a therapist’s help to be effective. To solve this problem, the purpose of this thesis is to create a new version of a finger rehabilitation system, which includes a lightweight 3D printed flexible exoskeleton finger that can be later adapted to create a complete rehabilitation glove. This glove will have actuators for opening and closing the finger (double action), an interface to provide simple rehabilitation movements, and low cost compared to the current designs. The system will make the rehabilitation process more successful for low-income patients in Mexico by making the therapy sessions more accessible, allowing the patient to be more likely to keep a consistent rehabilitation schedule. The mechanism was validated with three test subjects, each with different anthropomorphic finger dimentions. The main variable that was tested during the validation process are the flexion angles of the finger. These angles will be later compared to the subjects’ unrestricted flexion angles (without using the glove). Also, to find if the cost of the system was low enough, the reference is the average income of a rural Mexican family, which is around $400 USD as of 2016, and for the exoskeleton to be considered lightweight, a weight limit of 300 gr was established for the whole part of the system that had to be put over the patient’s finger and hand. The results of this study showed that the use of the system as mentioned earlier increased the angle of range of motion (ROM) in a significant way compared to current similar designs, improving the (ROM) of the Metacarpophalangeal (MCP) joint by 45% and 15% in the case of the Proximal interphalangeal (PIP) joint. With respect to the weight of the glove, this was around 80g for the parts that have to be located on the patient’s hand. The cost of manufacture and materials for this design was under $80 USD for one finger, which, if extrapolated for an entire glove, the cost would have stayed below $400 USD.