A 3D-printed soft orthotic hand actuated with twisted and coiled polymer muscles triggered by electromyography signals

Abstract

Various wearable robotic hands, prosthetic hands, and orthotic exoskeletons developed in the last decade aim to rehabilitate patients whose daily quality of life is affected from hand impairments – however, a majority of these devices are controlled by bulky, expensive, noisy, and uncomfortable actuators. Twisted and coiled polymer (TCP) muscles are novel smart actuators that address these key drawbacks. They have been utilized in soft robotics, hand orthosis exoskeletons, and powered hand orthotic devices; they are also light- weight, high-performance, and inexpensive to manufacture. Previously, TCP muscles have been controlled via power supplies with mechanical switches that are not portable, hence making it unfeasible for long term applications. In this work, a portable control system for TCP muscles via electromyography (EMG) signals that are captured through electrodes placed on the arm of the user and processed through a channel of electrical components to actuate 4-ply TCP muscles, which is demonstrated on a 3D-Printed soft orthotic hand. With portable EMG control, orthotic devices can become more independently accessible to the user, making these devices novel instruments for measuring, aiding, and expediting the progress of hand impairment rehabilitation.