Team 9

Optimizing Volume and Temperature Control for Lower Limb Prosthetics

Team Members:

Tyler Billingsly

Brodie Clemmer

Chamonix Michaud

Rachel Miller

Emerson Zahab

Team Mentors:

Dr. Sydney Schaefer, PhD - Arizona State University, SBHSE

Mr. Garth Knapp - Sound Prosthetics & Orthotics

YouTube Link:
View the video link below before joining the zoom meeting

Zoom Link:
https://asu.zoom.us/j/2348668608


Abstract

Maintaining comfortability within a prosthetic socket is subjected to several challenges that affect prosthesis users; mainly, these issues include residual limb volume fluctuations, and heat and perspiration build up within the enclosed socket environment. Literature suggests that prosthetic abandonment and lowered quality of life is largely caused by these aforementioned socket problems, specifically, elevated stump skin temperatures and the accompanying thermal discomfort. Lower-limb prosthetic users find themselves subjected to additional pathological conditions such as edema, lesions of the skin, and dermatitis due to this excess thermal load between their residual limb and their prosthetic socket. We present a novel personal thermoregulation device capable of absorbing this excess heat and fluxing it away from the residuum in order to maintain homeostasis. Combating this excess thermal load utilizes the high latent heat capacity of phase change material (PCM) CrodaTherm ™ 37. At homeostatic skin temperature, 33oC, it will absorb this excess heat without increasing its temperature, thus maintaining the temperature gradient that drives thermal conduction to pull the load away from the residuum. Volume fluctuation is addressed therapeutically by consequence of our design. Less frictional points of contact reduce shear stress which will improve the vacuum suspension and uniform pressure distribution of the socket system. This will minimize the effects of volume fluctuation that typical patients would experience. Through virtual mathematical modeling we demonstrated our device's ability to extract the heat generated through an average walking cadence, assumed to be largely controlled by metabolic heat up to 15W[1], and re-establish thermal equilibrium within 1000s. The research team anticipates that the thermal response system will adapt to diurnal physiological changes thus minimizing the discomfort and tissue degradation associated with the previously uncompromising nature of transfemoral socket systems.