A Body Power Hydraulic Prosthetic Hand

Limb amputations are a growing global challenge. Electrically powered prosthetic hands are heavy, expensive, and battery dependent. Body-powered prostheses offer a simpler and lighter alternative; however, existing designs require high body forces to operate, exhibit poor aesthetics, and have limited dexterity. This study aims to present a design of a hydraulically actuated soft bending finger with a simple and scalable manufacturing process. This is then realised into a five-fingered body-powered prosthetic hand that is lightweight, comfortable, and representative of a human hand. The actuator was formed from two silicone materials of different stiffness (Stiff Smooth-Sil 950 and flexible Ecoflex 00-30) and reinforced with double-helix fibres to generate bending under internal hydraulic pressure. A shoulder-mounted hydraulic system has been designed to convert scapular elevation and protraction into actuator pressure. Finite element analysis and physical tests were performed to examine the bending and blocking force performance of the actuators. The physical actuators achieved bending angles up to 230 degrees at 60 kPa and blocking forces of 5.9 N at 100 kPa. The prosthetic system was able to grasp and hold a 320-g water bottle. The results demonstrate a soft actuator design that provides simple and scalable manufacturing and shows how these actuators can be incorporated into a body-powered prosthesis. This study provides a preliminary demonstration of the feasibility of human-powered prosthetics and necessitates continued research. This work makes progress towards an affordable and functional body-powered prosthetic hand that can improve the lives of transradial amputees.