Prosthetic Thumb


Client is an individual who retains portions of fingers on right hand, and has had left arm and both feet amputated due to infection. He has requested a prosthesis for his right hand that can help him complete everyday tasks that are currently not possible for him to achieve. 


Goal and Objectives

Fall Quarter 2021 Project Goal: Deliver a functional thumb prosthesis to the client

Follow the engineering design process to develop several iterations in order to perfect a prothesis that will allow the client to accomplish all requested tasks while being comfortable to wear and not interfering with current body mobility. Design, test, and manufacture an individualized prosthesis that provides the ability to complete additional everyday tasks, including: hold a plate, open a pill bottle cap, hold a cup, pull a suitcase, and hold a pen, utensil, or toothbrush (utilizing a foam tube that items have been placed in).

Winter Quarter 2022 Project Goal: Perfect the prosthetic device and document the study of the molded liquid silicone used to optimize the prosthetic thumb's ability to hold common household objects for a specified period of time.

Design additional actuation method to supply additional tension, tightening the thumb around the object held. Study different types of molded liquid silicone rubber, and its parameters such as density, thickness, molding pattern, and adhesive method, to optimize the gripping ability of the designed prosthetic thumb. 


Interview client to assess and analyze needs (9/30/21)

Brainstorm design concepts (10/1/21)

Create a CAD model of the prosthetic thumb prototype (10/5/21)

3D print first prosthetic thumb prototype (10/6/21)

Adjust CAD model and 3D print second prosthetic thumb prototype (10/9/21)

Adjust CAD model and 3D print third prosthetic thumb prototype (10/12/21)

Perform calculations to determine degrees of freedom and force requirements (10/15/21)

Select actuation method: friction hinge (11/3/21)

Create CAD model of attachment method: clamshell arm cuff (11/10/21)

Design closure method for arm cuff: boa system with custm 3D-printed dial (11/15/21)

Test the prototype with client to identify revisions to be made, adjust/revise CAD model, and 3D print prosthetic thumb prototype

Obtain a 3D scan of residual hand to allow for a custom-fit attachment method (11/21/21)

Adjust CAD model for arm cuff to fit client's existing anatomy, and 3D print arm cuff prototype (11/29/21)

Finalize and fabricate final design before delivering to client (12/4/21)



Team Contact

Joseph Davis

Team Lead 2021-2022



Prof. David Reinkensmeyer

Professor of Mechanical and Aerospace Engineering, Anatomy and Neurobiology, Biomedical Engineering, and Physical Medicine and Rehabilitation



Final Report

Final Presentation

Midterm Report

Midterm Presentation

Project status: 
Academic year: 
Fall Poster: 
Winter Poster: