Design and Fabrication of a 4D-Printed Human Hand with Electrically Driven Muscle-Like Actuation

Loss of dexterity in the human hand due to amputation or injury remains a significant challenge, as conventional prosthetic solutions often lack the natural motion, comfort and anatomical realism required for everyday use. Current electrically actuated prostheses rely heavily on bulky motors and complex tendon routing, which limit miniaturization and lifelike function. This research focuses on CAD modeling, simulation, and iterative 4D-printing of a bioinspired human hand that integrates shape memory alloy (SMA) wires directly into muscle-like soft tissue layers beneath a flexible skin structure. A ball-and-socket joint with three degrees of freedom is employed at the thumb’s carpometacarpal (CMC) base to replicate natural opposition and rotation, while universal joints at the metacarpophalangeal (MCP) locations provide two degrees of freedom for flexion and abduction of each finger. Hinge joints are used at the distal and proximal interphalangeal (DIP and PIP) levels to allow single axis bending. The current CAD modeling efforts focus on joint design and motion analysis using SOLIDWORKS with simulations conducted in ANSYS to validate joint kinematics and the feasibility of SMA-based electrical actuation. The work also explores multi-material 4D-printing strategies using both FDM and SLA processes. This project aims to establish a modular, anatomically accurate, and electrically driven hand prototype to demonstrate how bioinspired smart structures can make next-generation prosthetic hands more accessible, functional and lifelike.