A Lightweight Embedded 3D-Printed Soft Robotic Finger Powered by SMA Artificial Muscle

• Lightweight 3D-printed soft finger powered by shape memory alloy • 23 g finger delivering 6.5 N peak fingertip force • Embedded soft finger with 100° flexion range • Modular, low-cost actuation module as groundwork for soft robotics Humans rely on intricate hand motions for daily living, yet prosthetic fingers are often bulky, noisy and expensive. Shape memory alloys (SMAs) combine high power-to-weight ratios, silent operation and affordability making them ideal for compact actuation systems. This work builds on these features to deliver a lightweight actuation solution tailored for compact and energy-efficient applications, presenting a 3D-printed soft robotic finger made of thermoplastic elastomer and actuated using a dual-wire configuration of SMA artificial muscle. The design leverages the Joule effect for the actuation of the smart material, controlled by a closed-loop PID algorithm, guided by feedback from embedded piezoresistive sensors measuring flexion angle and fingertip force. Two iterations of the finger were developed, with the second version optimizing SMA channel placement, resulting in faster actuation, improved repeatability, and enhanced force delivery. The final prototype achieves up to 100 ∘ of flexion in ∼ 4 seconds, passive extension in 13 seconds, and generates a peak fingertip force of 6.5 N under an 8 V power supply. These results demonstrate the feasibility of the proposed SMA-actuated finger module in terms of weight, flexion, and fingertip force. The presented prototype should be regarded as a building block for future prosthetic-hand development. The simplicity, low cost, and effectiveness of the design demonstrate its potential as a foundational component in next-generation prosthetic hands. Also, although demonstrated on a single soft finger, the actuator, sensing, and control approach are generalizable and can be adapted as compact, low-cost flexible articulations across a wide range of soft-robotic systems.