Aerospace engineering PhD candidate Carson Squibb and mechanical engineering junior Trevor LeMaster, who has a transfemoral amputation, use digital image correlation on a carbon fiber composite prosthetic socket to track limb deformations during simulated loading. Photograph courtesy of Virginia Tech

A Virginia Tech research team, led by Associate Professor Michael Philen, PhD, of the Kevin T. Crofton Department of Aerospace and Ocean Engineering, and Professor Michael Madigan, PhD, of the Grado Department of Industrial and Systems Engineering, has received a $400,000 National Science Foundation grant to study residual limb volume loss and develop smart prosthetic sockets to improve comfort and performance in prostheses. The team is collaborating with Brian Kaluf, CP, FAAOP, of Ability Prosthetics and Orthotics, Charlotte, NC.

Over the course of the 3-year grant, the researchers will be developing new techniques to accurately measure residual limb volume change and deformation throughout the day, as well as the changes in the fit of the prosthetic socket itself. Philen’s work in the Aerospace Structures and Materials Laboratory includes a technology known as fluidic flexible matrix composites. These composites have been demonstrated in aerospace structures, morphing structures, robotics, and wave energy conversion systems. When integrated into a prosthesis, fluidic flexible matrix composites can accommodate to residual limb volume loss and help maintain a comfortable fit for the user. Madigan’s Biomechanics Group brings expertise studying the dynamics of human movement, including gait, balance, and slip, trip, and fall prevention.

Digital image correlation and a clear diagnostic socket will be used to track strains (ie, deformation) on the residual limb during daily activities. Digital image correlation is an established technique for acquiring 3D strains and displacements on the surface of materials; applying this technique to socket fit will provide new insights into the relationship between strain and comfort. Additionally, the researchers are developing a high-precision laser scanning system to measure the shape and volume of the limb before and after completing the physical activities. Once they have a better understanding of residual limb deformation during active use, the researchers will work on developing a smart prosthetic socket employing fluidic flexible matrix composite technology. Wafers made of this composite integrated into the smart socket can achieve an increase in volume when pressurized, exhibit changes in stiffness, and be fabricated into a variety of shapes and configurations that can be tailored for the user.