3-D printed hand assisstive exoskeleton for actuated pinch and grasp

In the United States over 1 million Americans suffer from muscular disorders such as Multiple Sclerosis, Carpal Tunnel Syndrome and Parkinson´s disease. Muscular disorders can affect the skeletal muscles that control hand movements by reducing strength and dexterity resulting in a loss of the hand´s ability to perform everyday functional movements such as pinching and grasping. A power assistive exoskeleton was designed to amplify a user´s residual strength and restore functional movements. This device incorporates a multi-digit mechanism comprising of a thumb, index, and grouped third MRS (middle, ring, small) digit. Each digit will provide flexion/extension through the coupling of a solenoid pneumatic actuator and a double action pneumatic cylinder working in compression. The double action pneumatic cylinders are connected to a polymer-braided cable that can produce a force on each digit allowing it to actuate. The solenoid pneumatic actuator is powered through a control system that receives sensor feedback from force sensing resistors placed on each digit, and converts it to an electrical signal. Preliminary testing will include the utilization of forearm EMG data obtained when the user performs daily tasks such as picking up a pencil, a 5 lb bag, and a water bottle with the exoskeleton. These results should present a reduction in pinching and grasping effort with respect to normal force production in each subject tested, and thereby successfully amplifying these movements and restoring hand functionality.