Characterizing the mechanical properties of rapid liquid printed silicone for use in prosthetic liners

Abstract

Prosthetic socket liners have previously been commercially available only in set size increments. The Self Assembly Lab's new Rapid Liquid 3D printing will allow custom-fit flexible socket liners to be printed with medical-grade silicone, however the material characteristics of the silicone in this deposition pattern are not well understood. Under loaded conditions in a prosthetic socket, this uncertainty leads to suboptimal performance and comfort. The goal of this thesis project is to characterize the 3D printed soft silicone, which can then be used to 3D print custom-fit silicone socket liners that generate a custom pressure map on each residual limb. Samples of hyperelastic silicone were gathered from representative liners, their stress stretch curves were measured, and various hyperelastic models were fit to the data. The Ogden model was determined to yield the best fit for each specimen. These hyperelastic model parameters can be used to enable more accurate modeling and design of custom socket liners.