Mechanical DesignRoboticsProduct Design

Groove-Based 3D Printed Prosthetic Hand

Master's Thesis · Penn State Mechanical Engineering · 2025

2.1×

Stress reduction vs. non-grooved

250,000

Fatigue cycles completed

Independent motors

~$125

Estimated build cost

Overview

This project designed and fabricated a fully functional prosthetic hand using TPU-based 3D printing and soft robotic principles. The core contribution is a novel groove pattern along each phalange that reduces stress concentration, improves joint flexibility, and extends fatigue life — all without compromising grip strength. The design was validated through finite element analysis, physical fatigue testing, fingertip force benchmarking, and real-world grasping trials.

Designed a novel groove-based TPU finger to reduce stress concentration and improve bending durability vs. conventional tendon-driven designs.
Ran ANSYS parameter sensitivity studies (FEA) across groove height, thickness, and spacing — validated with response surface method statistical analysis.
Built a custom cyclic test bench with servo motor, tendon routing system, and load cell to run 250,000-cycle fatigue and force output experiments.
Integrated six DC motors, a servo-driven thumb, and Arduino-based control into a compact palm housing designed from 3D hand scans.
Demonstrated power and precision grasps across rigid, soft, and irregular objects using the fully assembled hand.

Design process

3D hand scan used as anatomical reference

Artec Space Spider 3D scan — used as anatomical reference for finger and palm geometry

SolidWorks exploded assembly — finger, palm, and motor housing components

Research data

ANSYS finite element analysis comparing Von Mises stress between the grooved and non-grooved finger designs under identical 20 mm tendon displacement loading. The groove pattern reduces peak stress by more than 50%, directly extending fatigue life.