Implantable finger prosthetic
Patent Pending: US Patent App. 63/791,061 - “Mechanically Actuated Implantable Finger Prosthesis”
Problems
Our prosthetic implant directly addresses clinical needs arising from severe joint degradation, typically associated with acute arthritis causing debilitating pain or traumatic injuries necessitating joint replacement. Specifically, our approach focuses on arthroplasty of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, areas critical for restoring functional hand movement and patient quality of life.
Existing Implants
Current MCP and PIP joint implants provide basic mechanical replacements without advanced sensing or precise motion control. As a result, post-surgery tendon weakening and scar tissue formation often limit patient mobility and function. Our design addresses these issues by incorporating EMG-based sensing and responsive actuation control, significantly enhancing accuracy, reducing response delay, and improving overall patient outcomes.
Prototype 1
Test-bench Setup
The initial prototype aimed to replicate basic finger mechanics through tendon-like actuation, focusing on sensing and control. This was validated using a test bench setup.
The flexure-based finger design achieves flat-fist and palm positions through EMG signals derived from arm muscle contractions.
Prototype 2
Wearable System
A wearable EMG sensor captures muscle contraction signals and transmits them wirelessly to the wearable actuation module. The module then controls a motor that pulls a tendon cable through a skin port attached to the finger, enabling the desired motion.
Using a wearable module integrating EMG sensors and a servo motor, the finger prosthetic achieves synchronized motion with the user’s hand movements.
Prototype 3
Teleoperation
Successfully assembled a finger prosthetic onto a wooden hand, achieving synchronized motion sensing and user control.
Future Step
Cadaver Lab Study
Our finger prosthetic was successfully implanted in a cadaver at Vanderbilt University Medical Center, demonstrating its effectiveness in restoring basic hand function.
In future designs, we will ensure full biocompatibility and improve the prosthetic’s structural integrity by using titanium or stainless steel.
Magnetic Actuation
We're exploring a non-invasive magnetic actuation approach to drive the tendon cable, eliminating the need for a skin port. An implanted linear rail will synchronize internal module movement with an external magnetic actuator, enabling precise, skin-contact-free control.
Collaborators at Vanderbilt University Medical Center:
Dr. Panambur L. Bhandari, MD; Mr. Justin D. Stehr, OT
Advisors:
Dr. Ranjana Sahai, Dr. Thomas J. Withrow, Dr. Jason Mitchell
Senior Design Team members:
Carlos Negrón Fernández, Grace Sparks, Mary Herman, Kaijia Chen