A Unique Body-Powered Terminal Device with Enhanced Grasping Capabilities for Individuals with Upper Limb Loss

PROJECT SUMMARY
Objective
Our objective is to develop and test a novel body-powered prosthetic terminal device. The device is the first
of its kind to exhibit both high and low grasp forces while still exhibiting exceptional strength and durability.
Significance
Upper limb prosthesis disuse and abandonment rates are alarmingly high, and individuals with upper limb
loss indicate that they would use prostheses if they exhibited improved functionality. Namely, there is a need for
a body-powered terminal device that displays excellent durability (allowing for push/pull tasks) as well as
enhanced gripping and grasping capabilities. The need for such work is captured in the results of our recent
survey of individuals with upper limb loss. The perspective of one such individual is captured in this quote:
A lot of emphasis continues to be placed on R&D for external powered solutions to upper extremity prostheses. Body
powered prostheses and activity specific prostheses R&D get almost no support. Both technologies should be developed
and researched...not just "bionic" technology…Pursue the research but balance the research with also a pursuit of
improving other more basic and more functional, less expensive reliable technologies.
Innovation
The Adaptive Grasp Force (AGF) terminal device is a body-powered device with excellent strength and
durability. Unlike commercially available body-powered devices, however, the AGF device can achieve a wide
range of grasp forces in a single device. This enhanced functionality is enabled by a novel mechanism which
exhibits non-backdrivable behavior, allowing for improved bimanual grasping functionality. The mechanism is
both low cost and highly durable (due to surface contact mechanics), facilitating rapid clinical adoption.
Approach
We intend to continue development of the AGF terminal device in order to test it in a series of functional
assessments relative to a commercially available body-powered device. We propose 3 specific aims: 1) develop
and fabricate the AGF device, 2) assess the device with able-bodied users in series of functional assessments,
and 3) perform durability and accelerated lifetime testing on the AGF device.
This approach is carefully designed to de-risk the AGF device from both a mechanical design and clinical
impact perspective. If the proposed aims are successful, we will continue development towards full clinical
deployment in a Phase II effort. In that effort, we plan to 1) redesign the AGF device based on lessons learned
during Phase I, 2) conduct controlled clinical assessments of the terminal device with upper limb prosthesis
users, and 3) conduct a take-home assessment of the device to examine its utility in real-world scenarios.

Grant Number: 1R43HD115423-01A1
NIH Institute/Center: NIH
Principal Investigator: Harrison Bartlett